阅读说明：本技术 一种盆池效应开孔排水管排水设计方法 (Drainage design method for basin-pool effect perforated drainage pipe ) 是由 沈志平 彭又贤 杨关文 付君宜 刘慧� 孙秀东 刘欢 尹林莉 于 2021-09-02 设计创作，主要内容包括：本发明提供一种盆池效应开孔排水管排水设计方法,该方法根据工程所处地区特征确定暴雨强度参数A-(1)、C、b、n、降雨历时T、暴雨重现期P、汇水面积S、地表径流系数ψ以及场地周边地下水渗入流量Q-(c),引入有效影响系数λ,计算修正设计流量Q-(p1)；根据管道流量计算方法计算排水管设计排水能力Q-(p2)；由Q-(p2)＝Q-(p1)求出排水管设计直径d-(p)；计算渗流流速v-(s)；将透水孔模拟为短管计算其理论计算流速v-(t)；由求出透水孔理论计算直径d-(t),根据工程经验确定透水孔设计直径d-(s)；本发明解决了在池盆效应中排水管开孔的设计问题,同时该方法不仅在池盆效应中应用,也可在其他需要埋设开孔透水管道的工程中应用,避免了盲目埋管的问题。(The invention provides a drainage design method for a basin-pool effect perforated drainage pipe, which determines a rainstorm intensity parameter A according to the characteristics of a region where a project is located 1 C, b and n, rainfall duration T, rainstorm reappearance period P, catchment area S, surface runoff coefficient psi and groundwater infiltration flow Q around the field c Introducing an effective influence coefficient lambda, and calculating and correcting a design flow Q p1 (ii) a Calculating the designed drainage capacity Q of the drainage pipe according to the pipeline flow calculation method p2 (ii) a From Q p2 ＝Q p1 Calculating the design diameter d of the drain pipe p (ii) a Calculating the seepage velocity v s (ii) a The permeable hole is simulated into a short pipe to calculate the theoretical calculation flow velocity v t (ii) a By Find outTheoretical calculation of diameter d of water permeable hole t Determining the design diameter d of the water permeable hole according to engineering experience s (ii) a The invention solves the design problem of the hole of the drain pipe in the basin effect, and simultaneously, the method is not only applied to the basin effect, but also applied to other projects needing to embed the hole permeable pipeline, thereby avoiding the problem of blind pipe embedding.)

1. a drainage design method for a basin effect perforated drainage pipe is characterized by comprising the following steps: the method comprises the following steps:

step one, calculating design flow Q according to site characteristics_p1：

Wherein Q is_p1To design the flow rate; lambda is the effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than or equal to 1.0; p is a heavy rain design recurrence period; t is the duration of rainfall; s is catchment area; phi is the surface runoff coefficient; q_cThe groundwater seepage flow around the field; a. the₁C, b, n-rainstorm intensity parameters;

step two, calculating the drainage capacity Q of the drainage pipe_p2：

Wherein Q is_p2The drainage capacity of the drain pipe is improved; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; d_pDesigning the diameter of the drain pipe;

step three, Q_p2＝Q_p1Calculating the design diameter d of the drain pipe_p：

Wherein d is_pDesigning the diameter of the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; lambda is the effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than or equal to 1.0; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; t is the duration of rainfall; p is a heavy rain design recurrence period; s is catchment area; psi is the surface runoff coefficient; q_cThe groundwater seepage flow around the field; a. the₁C, b, n-rainstorm intensity parameters;

step four, calculating the soil layer seepage flow velocity v at the position of the water permeable hole_s：

v_s＝ki_s

Wherein v is_sThe seepage velocity (m/s) at the water permeable holes; k is the permeability coefficient (m/s) of the soil; i.e. i_sThe hydraulic gradient from the earth surface to the deep buried position of the permeable hole is adopted;

step five, simulating the permeable holes into short pipes, and calculating the theoretical calculation flow velocity v of the short pipes_t：

Wherein v is_tCalculating the flow rate for the water permeable hole theory; n is_tThe roughness coefficient of the wall of the permeable hole; d_tCalculating the diameter for the water permeable hole theory; i.e. i_tHydraulic slope for water permeable holes;

step six, the method comprisesCalculating the theoretical diameter d of the water permeable hole_tThen determining the design diameter d of the water permeable hole_s：

Wherein d is_tCalculating the diameter for the water permeable hole theory; mu is the punching rate of the drainage pipeline material; i.e. i_tHydraulic slope for water permeable holes; k is the permeability coefficient of the soil; i.e. i_sThe hydraulic gradient from the earth surface to the deep buried position of the permeable hole is adopted; n is_tThe roughness coefficient of the wall of the permeable hole; v. of_sDesigning flow velocity for the water permeable holes;

step seven, calculating the water permeability Q of the total water permeable holes_tz：

Wherein Q is_tzThe total water permeable capacity of the water permeable holes; n is_tThe roughness coefficient of the wall of the permeable hole; xi is the effective coefficient of the normal use of the permeable holes; z_tThe number of the water permeable holes is designed; d_sDesigning the diameter of the water permeable holes; i.e. i_tHydraulic slope for water permeable holes;

step eight, Q_tz＝Q_p1Calculating the design quantity Z of the permeable holes_t：

Wherein Z is_tDesigning the number of the water permeable holes; xi is the effective coefficient of the normal use of the permeable holes; i.e. i_tHydraulic slope for water permeable holes; lambda is an effective influence coefficient of the surface water after permeation on the foundation pit; t is the duration of rainfall; p is a heavy rain design recurrence period; s is catchment area; psi is the surface runoff coefficient; q_cThe groundwater seepage flow around the field; a. the₁C, b, n-rainstorm intensity parameters; d_sDesigning the diameter of the water permeable holes;

step nine, calculating the theoretical calculation circumferential spacing x of the permeable holes according to the requirement of the punching rate of the pipeline material_tAnd a longitudinal spacing y_t：

Wherein x is_tCalculating the circumferential spacing for the water permeable hole theory; mu is the punching rate of the pipeline material; d_sDesigning the diameter of the water permeable holes; y is_tCalculating the longitudinal spacing for the water permeable hole theory;

step ten, solving the theoretical calculated length l of the drain pipe according to the arrangement range of the water permeable holes and the total number of the water permeable holes_p：

Wherein l_pCalculating the length for the drain pipe theory; d_pDesigning the diameter of the drain pipe; theta_jThe central angle of the drain pipe corresponding to the range of the base; d_sDesigning the diameter of the water permeable holes; x is the number of_tCalculating the circumferential spacing for the water permeable hole theory; y is_tCalculating the longitudinal spacing for the water permeable hole theory; z_tDesigning the number of the water permeable holes;

eleven steps of obtaining the theoretical length l of the drain pipe_pCalculating the design length l with the drainage perimeter C of the foundation pit_sAnd design number N_s：

When l is_pAt < 0.5C, N_s＝1，l_sC; when (n-0.5) C is less than l_p< nC, and when N is a positive integer, N_s＝n，l_s-nC; when nC < l_pN is less than (N +0.5) C, and when N is a positive integer, if N is selected_s＝n，l_sNot all but N_s＝n+1，l_s＝(n+1)C；

Twelfth, determining the circumferential distance x of the design of the water permeable holes according to the design length of the water drainage pipe and the design total number of the water permeable holes_tAnd a longitudinal spacing y_t：

x_s＝2x_t

Wherein, y_sCalculating the longitudinal spacing for the water permeable hole theory; x is the number of_tCalculating the circumferential spacing for the water permeable hole theory; z_tDesigning the number of the water permeable holes; l_sDesigning the length of the drain pipe; d_pDesigning the diameter of the drain pipe; theta_jThe central angle of the drain pipe corresponding to the range of the base; x is the number of_tCalculating the circumferential spacing for the water permeable hole theory; x is the number of_sCalculating the circumferential spacing for the water permeable hole theory; d_sThe diameter is designed for the water permeable holes.

2. The method of claim 1, wherein the method comprises the steps of: the design diameter of the pipeline is a modified design diameter.

3. The method of claim 1, wherein the method comprises the steps of: and in the fifth step, simulating the permeable holes into short pipes to calculate the flow rate of the permeable holes.

4. The method of claim 1, wherein the method comprises the steps of: and seventhly, simulating the water permeable holes into short pipes to calculate the water permeable capacity of the short pipes.

Technical Field

The invention relates to a drainage design method for a basin-pool effect perforated drainage pipe, and belongs to the technical field of foundation pit engineering drainage.

Background

Along with the continuous development and utilization of underground spaces of high-rise buildings, the excavation scale of foundation pits is continuously increased, the geological environment and hydrogeological conditions of the sites are destroyed, the original runoff conditions are changed and blocked, surface water and groundwater runoff are not smooth in rainstorm seasons, so that the surface water and groundwater runoff are collected to the foundation pits, the groundwater level rises suddenly, a basin effect is formed, a series of damages such as basement bottom plate cracking, uplifting and water seepage are caused, even a ground beam is broken and destroyed, and the normal and safe use of the buildings is seriously influenced.

The basin effect is very easy to be ignored in the building engineering, and a drainage prevention measure is lacked, so that potential safety hazards are buried for later use of the building engineering, and loss of lives and properties of people is caused, therefore, reasonable drainage design is carried out on the basin effect in the construction process, and the advance prevention is very necessary. When adopting the pipe laying drainage in basin effect precaution, the pipeline ability of permeating water is very crucial, to not drainage pipe itself, need set up the hole of permeating water on the pipeline, the design quantity, the design diameter, the design hoop interval of the hole of permeating water, the vertical interval of design, pipe laying root number and pipe laying length all relation whole drainage design the success or failure, nevertheless design basis and the design experience about this aspect are deficient relatively, are difficult to the accuracy design in the design.

Disclosure of Invention

In order to solve the technical problems, the invention provides a drainage design method of a basin effect perforated drainage pipe, which can effectively prevent the damage of the basin effect to buildings.

The invention is realized by the following technical scheme.

The invention provides a drainage design method for a basin effect perforated drainage pipe, which comprises the following steps:

step one, calculating design flow Q according to site characteristics_p1：

Wherein Q is_p1To design the flow rate; lambda is the effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than or equal to 1.0; p is a heavy rain design recurrence period; t is the duration of rainfall; s is catchment area; psi is the surface runoff coefficient; q_cThe groundwater seepage flow around the field; a. the₁C, b, n-rainstorm intensity parameter;

step two, calculating the drainage capacity Q of the drainage pipe_p2：

Wherein Q is_p2The drainage capacity of the drain pipe is improved; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; d_pDesigning the diameter of the drain pipe;

step three, Q_p2＝Q_p1Calculating the design diameter d of the drain pipe_p：

Wherein d is_pDesigning the diameter of the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; lambda is the effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than or equal to 1.0; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; t is the duration of rainfall; p is a heavy rain design recurrence period; s is catchment area; psi is the surface runoff coefficient; q_cThe groundwater seepage flow around the field; a. the₁C, b, n-rainstorm intensity parameter;

step four, calculating the soil layer seepage flow velocity v at the position of the water permeable hole_s：

v_s＝ki_s

Wherein v is_sThe seepage velocity (m/s) at the water permeable holes; k is the permeability coefficient (m/s) of the soil; i.e. i_sThe hydraulic gradient from the earth surface to the deep buried position of the permeable hole is adopted;

step five, simulating the permeable holes into short pipes, and calculating the theoretical calculation flow velocity v of the short pipes_t：

Wherein v is_tCalculating the flow rate for the water permeable hole theory; n is_tThe roughness coefficient of the wall of the permeable hole; d_tCalculating the diameter for the water permeable hole theory; i.e. i_tHydraulic slope for water permeable holes;

step six, the method comprisesCalculating the theoretical diameter d of the water permeable hole_tThen determining the design diameter d of the water permeable hole_s：

Wherein d is_tCalculating the diameter for the water permeable hole theory; mu is the punching rate of the drainage pipeline material; i.e. i_tHydraulic slope for water permeable holes; k is the permeability coefficient of the soil; i.e. i_sThe hydraulic gradient from the earth surface to the deep buried position of the permeable hole is adopted; n is_tThe roughness coefficient of the wall of the permeable hole; v. of_sDesigning flow velocity for the water permeable holes;

step seven, calculating the water permeability Q of the total water permeable holes_tz：

Wherein Q is_tzThe total water permeable capacity of the water permeable holes; n is_tThe roughness coefficient of the wall of the permeable hole; xi is the effective coefficient of the normal use of the permeable holes; z_tThe number of the water permeable holes is designed; d_sDesigning the diameter of the water permeable holes; i.e. i_tHydraulic slope for water permeable holes;

step eight, Q_tz＝Q_p1Calculating the design quantity Z of the permeable holes_t：

Wherein Z is_tDesigning the number of the water permeable holes; xi is the effective coefficient of the normal use of the permeable holes; i.e. i_tHydraulic slope for water permeable holes; lambda is an effective influence coefficient of the surface water after permeation on the foundation pit; t is the duration of rainfall; p is a heavy rain design recurrence period; s is catchment area; psi is the surface runoff coefficient; q_cThe groundwater seepage flow around the field; a. the₁C, b, n-rainstorm intensity parameter; d_sDesigning the diameter of the water permeable holes;

step nine, calculating the theoretical calculation circumferential spacing x of the permeable holes according to the requirement of the punching rate of the pipeline material_tAnd a longitudinal spacing y_t：

Wherein x is_tCalculating the circumferential spacing for the water permeable hole theory; mu is the punching rate of the pipeline material; d_sDesigning the diameter of the water permeable holes; y is_tCalculating the longitudinal spacing for the water permeable hole theory;

step ten, solving the theoretical calculated length l of the drain pipe according to the arrangement range of the water permeable holes and the total number of the water permeable holes_p：

Wherein l_pCalculating the length for the drain pipe theory; d_pDesigning the diameter of the drain pipe; theta_jThe central angle of the drain pipe corresponding to the range of the base; d_sDesigning the diameter of the water permeable holes; x is the number of_tCalculating the circumferential spacing for the water permeable hole theory; y is_tCalculating the longitudinal spacing for the water permeable hole theory; z_tDesigning the number of the water permeable holes;

eleven steps of obtaining the theoretical length l of the drain pipe_pCalculating the design length l with the drainage perimeter C of the foundation pit_sAnd design number N_s：

When l is_pAt < 0.5C, N_s＝1，l_sC; when (n-0.5) C is less than l_p< nC, and when N is a positive integer, N_s＝n，l_s-nC; when nC < l_pN is less than (N +0.5) C, and when N is a positive integer, if N is selected_s＝n，l_sNot all but N_s＝n+1，l_s＝(n+1)C；

Twelfth, determining the circumferential distance x of the design of the water permeable holes according to the design length of the water drainage pipe and the design total number of the water permeable holes_tAnd a longitudinal spacing y_t：

x_s＝2x_t

Wherein, y_sCalculating the longitudinal spacing for the water permeable hole theory; x is the number of_tCalculating the circumferential spacing for the water permeable hole theory; z_tDesigning the number of the water permeable holes; l_sDesigning the length of the drain pipe; d_pDesigning the diameter of the drain pipe; theta_jThe central angle of the drain pipe corresponding to the range of the base; x is the number of_tCalculating the circumferential spacing for the water permeable hole theory; x is the number of_sCalculating the circumferential spacing for the water permeable hole theory; d_sDesigning the diameter of the water permeable holes;

the design diameter of the pipeline is a modified design diameter.

And in the fifth step, simulating the permeable holes into short pipes to calculate the flow rate of the permeable holes.

And seventhly, simulating the water permeable holes into short pipes to calculate the water permeable capacity of the short pipes.

The invention has the beneficial effects that: when the pipe burying drainage design is carried out in the basin effect, a calculation analysis method is provided for the design quantity, the design diameter, the design circumferential spacing, the design longitudinal spacing, the pipe burying number and the pipe burying length of the water permeable holes of the drainage pipe.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a schematic view of a drainage plane in an embodiment of the present invention;

FIG. 3 is a schematic sectional view of a drain according to an embodiment of the present invention;

FIG. 4 is a cross-sectional view of a drain pipe according to an embodiment of the present invention;

FIG. 5 is a schematic view showing the drain pipe being unfolded according to the embodiment of the present invention;

in the figure: 1-catchment area, 2-foundation pit, 3-basement exterior wall, 4-foundation pit bottom line, 5-drainage pipe base, 6-drainage pipe, 7-water collecting well, 8-reinforced concrete cover plate, 9-basement bottom plate, 10-foundation pit side wall, 11-permeable hole and 12-drainage pipe designed water level elevation.

Detailed Description

The technical solution of the present invention is further described below, but the scope of the claimed invention is not limited to the described.

Example 1

A design method for drainage of a basin-pool effect perforated drainage pipe is suitable for drainage arrangement shown in figures 2 and 3, a foundation pit 2 is located in a catchment area 1, measurement and setting-off are carried out after excavation of the foundation pit is finished to determine the position of a basement outer wall 3, a drainage pipe base 5 is poured between a bottom side line 4 of the foundation pit and the basement outer wall 3, a drainage pipe 6 is arranged, a water collecting well 7 is built at the same time, a reinforced concrete cover plate 8 is arranged in the water collecting well, the drainage pipe 6 is connected with the water collecting well 7, collected water of the water collecting well 7 is drained out of the influence range of the foundation pit 2 through a pumping and drainage facility, a basement bottom plate 9 and the basement outer wall 3 are poured, and finally backfilling is carried out between the basement outer wall 3 and a foundation pit side wall 10. The drain pipe 6 is provided with a water permeable hole 11 in the range above the drain pipe base 5.

As shown in FIG. 1, a design method for drainage of a basin effect perforated drain pipe comprises the following steps:

step one, calculating design flow Q according to site characteristics_p1：

In the formula Q_p1To design flow (L/s); lambda is the effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than or equal to 1.0; p is the heavy rain design recurrence period (year); t is rainfall duration (min); s is catchment area (hm)²) (ii) a Psi is the surface runoff coefficient; q_cThe underground water infiltration flow (L/s) around the site is obtained; a. the₁C, b, n-rainstorm intensity parameters, and the data can be obtained by looking up the data.

Step two, calculating the drainage capacity Q of the drainage pipe_p2：

In the formula Q_p2Draining capacity (L/s) for the drain; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; d_pIs a rowThe design diameter (m) of the water pipe;

step three, Q_p2＝Q_p1Calculating the design diameter d of the drain pipe_p：

In the formula d_pDesigning the diameter (m) for the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; lambda is the effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than or equal to 1.0; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; t is rainfall duration (min); p is the heavy rain design recurrence period (year); s is catchment area (hm)²) ); psi is the surface runoff coefficient; q_cThe underground water infiltration flow (L/s) around the site is obtained; a. the₁C, b, n-rainstorm intensity parameters, and data are searched to obtain the parameters;

step four, calculating the soil layer seepage flow velocity v at the position of the water permeable hole_s：

v_s＝ki_s

V in the formula_sThe seepage velocity (m/s) at the water permeable holes; k is the permeability coefficient (m/s) of the soil; i.e. i_sThe hydraulic gradient from the earth surface to the deep buried position of the permeable hole is adopted;

step five, simulating the permeable holes into short pipes, and calculating the theoretical calculation flow velocity v of the short pipes_t：

V in the formula_tCalculating the flow velocity (m/s) for the water permeable hole theory; n is_tThe roughness coefficient of the wall of the permeable hole; d_tCalculating the diameter for the water permeable hole theory; i.e. i_tHydraulic slope for water permeable holes;

step six, the method comprisesTheory of pore penetrationCalculating the diameter d_tThen determining the design diameter d of the water permeable hole_s：

In the formula d_tCalculating the diameter (m) for the water permeable hole theory; mu is the punching rate of the drainage pipeline material; i.e. i_tHydraulic slope for water permeable holes; k is the permeability coefficient (m/s) of the soil; i.e. i_sThe hydraulic gradient from the earth surface to the deep buried position of the permeable hole is adopted; n is_tThe roughness coefficient of the wall of the permeable hole;

step seven, calculating the water permeability Q of the total water permeable holes_tz：

In the formula Q_tzTotal water permeability (L/s); n is_tThe roughness coefficient of the wall of the permeable hole; xi is the effective coefficient of the normal use of the permeable holes; z_tThe number of the water permeable holes is designed; d_sDesigning the diameter (m) for the water permeable holes; i.e. i_tHydraulic slope for water permeable holes;

step eight, Q_tz＝Q_p1Calculating the design quantity Z of the permeable holes_t：

Z in the formula_tDesigning the number (number) of the water permeable holes; xi is the effective coefficient of the normal use of the permeable holes; i.e. i_tHydraulic slope for water permeable holes; lambda is an effective influence coefficient of the surface water after permeation on the foundation pit; t is rainfall duration (min); p is the heavy rain design recurrence period (year); s is catchment area (hm)²) (ii) a Psi is the surface runoff coefficient; q_cThe underground water infiltration flow (L/s) around the site is obtained; a. the₁C, b, n-rainstorm intensity parameters, and data are searched to obtain the parameters; d_sDesigning the diameter (m) for the water permeable holes;

nine steps and rootAccording to the requirement of the punching rate of the pipeline material, calculating the circumferential distance x of the theoretical calculation of the water permeable holes_tAnd a longitudinal spacing y_t：

X in the formula_tCalculating the circumferential spacing (m) for the water permeable hole theory; mu is the punching rate of the pipeline material; d_sDesigning the diameter (m) for the water permeable holes; y is_tCalculating the longitudinal spacing (m) for the water permeable hole theory;

step ten, solving the theoretical calculated length l of the drain pipe according to the arrangement range of the water permeable holes and the total number of the water permeable holes_p：

In the formula_pCalculating the length (m) for the drain pipe theory; d_pDesigning the diameter (m) for the drain pipe; theta_jThe central angle (°) of the drain pipe corresponding to the range of the base; d_sDesigning the diameter (m) for the water permeable holes; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; y is_tCalculating the longitudinal spacing (m) for the water permeable hole theory; z_tDesigning the number (number) of the water permeable holes;

eleven steps of obtaining the theoretical length l of the drain pipe_pCalculating the design length l with the drainage perimeter C of the foundation pit_sAnd design number N_s：

When l is_pAt < 0.5C, N_s＝1，l_sC; when (n-0.5) C is less than l_p< nC, and when N is a positive integer, N_s＝n，l_s-nC; when nC < l_pN is less than (N +0.5) C, and when N is a positive integer, if N is selected_s＝n，l_sNot all but N_s＝n+1，l_s＝(n+1)C；

The twelve steps,Determining the circumferential distance x of the design of the permeable holes according to the design length of the drainage pipe and the design total number of the permeable holes_tAnd a longitudinal spacing y_t：

x_s＝2x_t

x_s＝2x_t

Y in the formula_sCalculating the longitudinal spacing (m) for the water permeable hole theory; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; z_tDesigning the number (number) of the water permeable holes; l_sDesigning the length (m) for the drain pipe; d_pDesigning the diameter (m) for the drain pipe; theta_jThe central angle (°) of the drain pipe corresponding to the range of the base; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; x is the number of_sCalculating the circumferential spacing (m) for the water permeable hole theory;

specifically, in the step one, the influence of groundwater permeation around the site and the actual influence coefficient after permeation are considered, so that the design flow is reasonably determined.

Specifically, the design diameter of the pipeline in the third step is the corrected design diameter.

Specifically, in the fifth step, the water permeable holes are simulated into short pipes to calculate the flow velocity.

Specifically, a relational expression between the seepage velocity and the flow velocity of the water permeable holes is established in the sixth step.

And concretely, simulating the water permeable holes into short pipes to calculate the water permeable capacity of the short pipes.

Specifically, the eighth step is to establish a relation between the design flow and the water permeability of the water permeable holes to calculate the total number of the water permeable holes.

Specifically, in the ninth step, the influence of punching on the rigidity of the material is considered, namely, the relation between the punching rate of the material and the diameter and the distance is established to calculate the theoretical circumferential and longitudinal distances.

Specifically, the theoretical length of the drain pipe is obtained in the step ten.

Specifically, the design length and the design number of the drainage pipes are determined according to the relation between the theoretical length and the drainage perimeter of the foundation pit.

Specifically, the design circumferential spacing and the longitudinal spacing of the water permeable holes are obtained in the twelfth step.

In this way, the design diameter, number, spacing, length and number of the water permeable holes can be obtained by correcting the design flow and the design diameter of the water drainage pipe.

Example 2

A basin effect drain pipe drainage design method comprises the following steps:

the method comprises the following steps: obtaining a rainstorm intensity parameter A by looking up a table according to the rainstorm intensity statistics of the area where the engineering is located₁C, b and n, and determining the rainfall duration T, the design rainstorm reappearance period P, the catchment area S and the surface runoff coefficient psi according to the site and engineering characteristics. Although the surface water causing the effect of the basin is mainly the atmospheric rainfall, the formation of the basin effect is also aggravated by the leakage of pipelines and the unreasonable discharge of domestic water and municipal water, so the scheme not only considers the atmospheric rainfall seepage flow Q_sSimultaneously considering the groundwater infiltration flow Q around the site_cIn addition, because part of underground water may flow away along other channels such as bedrock fractures and the like, the scheme introduces an effective influence coefficient lambda and calculates the corrected design flow Q according to the following formula_p1。

In the formula Q_p1To design flow (L/s); lambda is the effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than or equal to 1.0; p is the heavy rain design recurrence period (year); t is rainfall duration (min); s is catchment area (hm)²) (ii) a Psi is the surface runoff coefficient; q_cThe permeation flow rate (L/s) of other surface water; a. the₁C, b, n-rainstorm intensity parameters, and the data can be obtained by looking up the data.

Step two: the drainage facility chooses for use circular drain pipe that punches, and the drain pipe arranges in the foundation ditch edge, and the drain pipe is connected with the sump pit, and the sump pit installation facility of drawing water takes water out the foundation ditch influence scope outside. Calculating the drainage capacity of the drain pipe according to the following formulaForce Q_p2。

In the formula Q_p2Draining capacity (L/s) for the drain; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; d_pThe diameter (m) is designed for the drain pipe.

Step three: to solve the problem of basin effect, the drainage capacity of the drainage pipe should satisfy the design flow rate, namely Q_p2＝Q_p1Thereby obtaining the corrected design diameter d of the drain pipe_p。

In the formula d_pDesigning the diameter (m) for the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; lambda is an effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than 1.0; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; t is rainfall duration (min); p is the heavy rain design recurrence period (year); s is catchment area (hm)²) (ii) a Psi is the surface runoff coefficient; q_cThe underground water infiltration flow (L/s) around the site is obtained; a. the₁C, b, n-rainstorm intensity parameters, and the data can be obtained by looking up the data.

Step four: calculating the seepage velocity v of surface water flowing through the foundation pit backfill soil layer according to the following formula_s。

v_s＝ki_s

V in the formula_sThe seepage velocity (m/s) at the water permeable holes; k is the permeability coefficient (m/s) of the soil; i.e. i_sThe slope of the water power from the earth surface to the deep part of the water permeable hole.

Step five: simulating the permeable holes as short tubes according to the following formulaCalculating the flow velocity v of the water permeable holes_t。

V in the formula_tThe flow rate (m/s) of the water permeable holes; n is_tThe roughness coefficient of the wall of the permeable hole; d_tCalculating the diameter for the water permeable hole theory; i.e. i_tIs a hydraulic slope of a water permeable hole.

Step six: byCalculating the theoretical diameter d of the water permeable hole_tThe design diameter d is determined according to engineering experience rounding_s；

In the formula d_tCalculating the diameter (m) for the water permeable hole theory; mu is the punching rate of the pipeline material; i.e. i_tHydraulic slope for water permeable holes; k is the permeability coefficient (m/s) of the soil; i.e. i_sThe hydraulic gradient from the earth surface to the deep buried position of the permeable hole is adopted; n is_tThe roughness coefficient of the pore wall of the permeable pore.

Step seven: calculating the water permeability Q of the total water permeable holes_tz。

In the formula Q_tzTotal water permeability (L/s); n is_tThe roughness coefficient of the wall of the permeable hole; xi is the effective coefficient of the water permeable holes; z_tThe number of the water permeable holes is designed; d_sDesigning the diameter (m) for the water permeable holes; i.e. i_tIs a hydraulic slope of a water permeable hole.

Step eight: from Q_tz＝Q_p1Calculating the design quantity Z of the permeable holes_t；

Z in the formula_tDesigning the number (number) of the water permeable holes; xi is the effective coefficient of the water permeable holes; i.e. i_tHydraulic slope for water permeable holes; lambda is an effective influence coefficient of the surface water after permeation on the foundation pit; t is rainfall duration (min); p is the heavy rain design recurrence period (year); s is catchment area (hm)²) (ii) a Psi is the surface runoff coefficient; q_cThe underground water infiltration flow (L/s) around the site is obtained; a. the₁C, b, n-rainstorm intensity parameters, and data are searched to obtain the parameters; d_sThe diameter (m) is designed for the water permeable holes.

Step nine: the pressure resistance of the pipeline is reduced due to the influence of too dense arrangement of the permeable holes, so that the circumferential distance x of theoretical calculation of the permeable holes is calculated according to the requirement of the punching rate of the pipeline material_tAnd a longitudinal spacing y_t；

X in the formula_tCalculating the circumferential spacing (m) for the water permeable hole theory; mu is the punching rate of the pipeline material; d_sDesigning the diameter (m) for the water permeable holes; y is_tThe longitudinal spacing (m) is calculated for the water permeable holes theory.

Step ten: calculating the theoretical calculated length l of the drain pipe according to the arrangement range of the permeable holes and the total number of the permeable holes_p；

In the formula_pCalculating the length (m) for the drain pipe theory; d_pDesigning the diameter (m) for the drain pipe; theta_jThe central angle (°) of the drain pipe corresponding to the range of the base; d_sDesigning the diameter (m) for the water permeable holes; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; y is_tCalculating the longitudinal spacing (m) for the water permeable hole theory; z_tThe number (number) of the water permeable holes is designed.

Step eleven: according to the theoretical length l of the drain pipe_pCalculating the design length l from the drainage perimeter C of the foundation pit_sAnd design number N_s；

When l is_pAt < 0.5C, N_s＝1，l_sC; when (n-0.5) C is less than l_pN is a positive integer < nC_s＝n，l_s-nC; when nC < l_pIf N is less than (N +0.5) C (N is a positive integer), N is selected_s＝n，l_sIf nC, the perforating rate of the drain pipe needs to be increased, and the pressure resistance of the drain pipe needs to be improved, otherwise N_s＝n+1，l_s＝(n+1)C。

Step twelve: determining the circumferential distance x of the design of the permeable holes according to the design length of the drainage pipe and the design total number of the permeable holes_sAnd a longitudinal spacing y_s；

x_s＝2x_t

Y in the formula_sCalculating the longitudinal spacing (m) for the water permeable hole theory; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; z_tDesigning the number (number) of the water permeable holes; l_sDesigning the length (m) for the drain pipe; d_pDesigning the diameter (m) for the drain pipe; theta_jThe central angle (°) of the drain pipe corresponding to the range of the base; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; x is the number of_sCalculating circumferential spacing (m) for water permeable holes theory, the water permeable holes being spaced apart from both ends

Example 3

A design method for drainage of a basin effect perforated drainage pipe comprises the following specific implementation processes:

in the step one, the storm intensity parameter A of the area where the project is located₁C, b, n, the duration T of rainfall and the designed rainstorm reappearing period P, and the rainstorm intensity q is calculated according to the following formula.

In the formula, q is the designed rainstorm intensity [ L/(s.hm)²)](ii) a T is rainfall duration (min); p is the heavy rain design recurrence period (year); a. the₁C, b, n-rainstorm intensity parameters, and the data can be obtained by looking up the data.

Determining catchment area S and surface runoff coefficient psi according to topographic features around the field, and calculating rainwater seepage flow Q according to the following formula_s。

Q_sqS (1-psi) -formula 1.2

In the formula Q_sThe rainwater infiltration flow rate (L/s); q is the design rainstorm intensity [ L/(s.hm)²)](ii) a Psi is the surface runoff coefficient; s is catchment area (hm)²)。

Substituting formula 1.1 for formula 1.2 to obtain rainwater penetration flow Q_sThe following were used:

in the formula Q_sThe rainwater infiltration flow rate (L/s); t is rainfall duration (min); p is the heavy rain design recurrence period (year); s is catchment area (s.hm)²) (ii) a Psi is the surface runoff coefficient.

In the whole design, besides the main influence of atmospheric rainfall, the influence of groundwater infiltration flow around the site is considered, meanwhile, due to the influence of rock-soil fracture permeable channels and the like, the effective influence coefficient lambda of surface water infiltration on the foundation pit is determined according to geological conditions, and the design flow Q is corrected_p1。

Q_p1＝λ(Q_s+Q_c) - (formula 1.4) -

In the formula Q_p1To design flow (L/s); q_sThe rainwater infiltration flow rate (L/s); q_cThe underground water infiltration flow (L/s) around the site is obtained; and lambda is the effective influence coefficient of surface water permeation on the foundation pit, and lambda is less than 1.0.

Substituting equation 1.3 into 1.4, the design flow was found as follows:

in the formula Q_p1To design flow (L/s); lambda is an effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than 1.0; p is the heavy rain design recurrence period (year); t is rainfall duration (min); s is catchment area (s.hm)²) (ii) a Psi is the surface runoff coefficient; q_cThe underground water infiltration flow (L/s) around the site is obtained; a. the₁C, b, n-rainstorm intensity parameters, and the data can be obtained by looking up the data.

In the second step, the drainage capacity Q of the drainage pipe is calculated according to the following formula_p2。

R in the formula_pIs the hydraulic radius (m) of the drain pipe; d_pDesigning the diameter (m) for the drain pipe; theta_pThe radius of the vertical direction of the drain pipe rotates anticlockwise to the drain pipe around the circle center to design a rotation angle of the water level elevation.

V in the formula_pThe flow velocity (m/s) of the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; r_pIs the hydraulic radius (m) of the drain pipe; i.e. i_pThe hydraulic slope is designed for the drain pipe.

In the formula F_pFor the water discharge pipe cross-sectional area (m)²)；d_pDesigning the diameter (m) for the drain pipe; theta_pThe radius of the vertical direction of the drain pipe rotates anticlockwise to the drain pipe around the circle center to design a rotation angle of the water level elevation.

Q_p2＝1000F_pv_p- (formula 2.4) -

In the formula Q_p2Draining capacity (L/s) for the drain; f_pFor the water discharge pipe cross-sectional area (m)²)；v_pThe flow rate (m/s) of the drain pipe is shown.

The drainage capacity of the drainage pipe is obtained by substituting the formula 2.1-2.3 into the formula 2.4 as follows:

in the third step, the drainage capacity of the drainage pipe meets the design flow requirement, namely Q_p1＝Q_p2Substituting the formula 1.5 and the formula 2.5 to derive the corrected design diameter d of the drain pipe_p。

In the formula d_pDesigning the diameter (m) for the drain pipe; n is_pThe pipe wall roughness coefficient of the drain pipe; lambda is an effective influence coefficient of the surface water after permeation on the foundation pit, and lambda is less than 1.0; theta_pDesigning a rotation angle of the water level elevation for the radius of the drain pipe in the vertical direction to rotate anticlockwise around the circle center to the drain pipe; i.e. i_pDesigning hydraulic slope for the drain pipe; t is rainfall duration (min); p is the heavy rain design recurrence period (year); s is catchment area (hm)²) (ii) a Psi is the surface runoff coefficient; q_cThe underground water infiltration flow (L/s) around the site is obtained; a. the₁C, b, n-rainstorm intensity parameters, and the data can be obtained by looking up the data.

And (3) the soil layer seepage flow velocity at the permeable hole in the fourth step:

v_s＝ki_s- (formula 4.1) -

V in the formula_sThe seepage velocity (m/s) at the water permeable holes; k is the permeability coefficient (m/s) of the soil; i.e. i_sThe slope of the water power from the earth surface to the deep part of the water permeable hole.

In the fifth step, the permeable holes are simulated into short pipes, and the flow velocity v of the short pipes is calculated according to the following formula_t；

R in the formula_tThe hydraulic radius (m) of the water permeable holes; d_tThe diameter (m) is calculated for the water permeable pores theoretically.

V in the formula_tCalculating the flow velocity (m/s) for the water permeable hole theory; r_tThe hydraulic radius (m) of the water permeable holes; i.e. i_tHydraulic slope for water permeable holes; n is_tThe roughness coefficient of the pipe wall of the water permeable hole is shown.

The flow rate through the pores was determined by substituting equation 5.1 for equation 5.2 as follows:

v in the formula_tCalculating the flow velocity (m/s) for the water permeable hole theory; n is_tThe roughness coefficient of the pipe wall of the water permeable hole; d_tCalculating the diameter (m) for the water permeable hole theory; i.e. i_tIs a hydraulic slope of a water permeable hole.

Establishing a relation between the permeation flow rate at the position of the water permeable hole and the theoretical calculation flow rate of the water permeable hole in the sixth stepSubstituting the equations 4.1 and 5.3 into the theoretical calculation of diameter d of water permeable hole_tDetermining the design diameter d of the water permeable hole according to engineering experience_s，d_s≥d_T；

In the formula d_tCalculating the diameter (m) for the water permeable hole theory; mu is the punching rate of the drain pipe material; i.e. i_tHydraulic slope for water permeable holes; k is the soil permeability coefficient (m/s); i.e. i_sFor burying depth from earth surface to permeable holeHydraulic gradient; n is_tThe roughness coefficient of the pipe wall of the water permeable hole is shown.

In the seventh step, the total number of the water permeable holes is set to be Z_tDesigning the diameter d according to the water permeable holes determined in the step six_sCalculating the total water permeability of the water permeable holes Q by the following formula_Tz；

R in the formula_tThe hydraulic radius (m) of the water permeable holes; d_sThe diameter (m) is designed for the water permeable holes.

V in the formula_sDesigning flow velocity (m/s) for the water permeable holes; r_tThe hydraulic radius (m) of the water permeable holes; i.e. i_tHydraulic slope for water permeable holes; n is_tThe roughness coefficient of the pipe wall of the water permeable hole is shown.

The flow rate through the pores was determined by substituting equation 5.1 for equation 5.2 as follows:

v in the formula_tDesigning flow velocity (m/s) for the water permeable holes; n is_tThe roughness coefficient of the pipe wall of the water permeable hole; d_sDesigning the diameter (m) for the water permeable holes; i.e. i_tIs a hydraulic slope of a water permeable hole.

In the formula F_tFor a single water-permeable hole cross-sectional area (m)²)；d_sThe diameter (m) is designed for the water permeable holes.

Q_td＝1000F_tv_s- (formula 7.5) -

In the formula Q_tdFor single penetration of waterWater permeability (short pipe drainage) capacity (L/s); f_tFor a single water-permeable hole cross-sectional area (m)²)；v_tThe flow velocity (m/s) is designed for the water permeable pores.

Because the situation of blockage and damage of partial permeable holes is difficult to avoid, the effective coefficient xi of the permeable holes in normal use is considered, and the calculation formula of the permeable (short pipe drainage) capacity of the drainage pipe is as follows:

Q_tz＝ξZ_tQ_td- (formula 7.6) -

In the formula Q_tzThe water permeability (L/s) of the drain pipe; xi is the effective coefficient of the normal use of the permeable holes; z_tDesigning the number (number) of the water permeable holes; q_tdThe water permeability (short pipe drainage) of a single water permeable hole is L/s.

The water permeability of the drain pipe is determined by taking expressions 7.3, 7.4 and 7.5 into expression 7.6 as follows:

in the formula Q_tzTotal water permeability (L/s); n is_tThe roughness coefficient of the wall of the permeable hole; xi is the effective coefficient of the water permeable holes; z_tThe number of the water permeable holes is designed; d_sDesigning the diameter (m) for the water permeable holes; i.e. i_tThe short pipe hydraulic slope is simulated for the permeable holes.

In step eight, the water permeability should meet the design flow, namely Q_tz＝Q_p1Calculating the design number Z of water permeable holes by substituting the equations 7.7 and 1.5_t：

Z in the formula_tDesigning the number (number) of the water permeable holes; xi is the effective coefficient of the normal use of the permeable holes; i.e. i_tHydraulic slope for water permeable holes; lambda is an effective influence coefficient of the surface water after permeation on the foundation pit; t is rainfall duration (min); p is the heavy rain design recurrence period (year); s is catchment area (hm)²) (ii) a Psi is the surface runoff coefficient; q_cIs a fieldGround periphery groundwater infiltration flow (L/s); a. the₁C, b, n-rainstorm intensity parameters, and data are searched to obtain the parameters; d_sThe diameter (m) is designed for the water permeable holes.

In the ninth step, in order to ensure the pressure resistance of the drainage pipeline, the punching rate of the drainage pipeline meets the requirement of the punching rate of the material, and the circumferential distance x of the theoretical calculation of the water permeable holes is calculated according to the following formula_tAnd a longitudinal spacing y_tAs follows.

x_t＝y_t- (formula 9.2) -

Mu in the formula is the punching rate of the pipeline material; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; y is_tCalculating the longitudinal spacing (m) for the water permeable hole theory; d_sThe diameter (m) is designed for the water permeable holes.

Theoretical calculation of circumferential spacing xt and longitudinal spacing y of permeable holes by substituting formula 9.2 for formula 9.1_tThe following were used:

x in the formula_tCalculating the circumferential spacing (m) for the water permeable hole theory; mu is the punching rate of the pipeline material; d_sDesigning the diameter (m) for the water permeable holes; y is_tThe longitudinal spacing (m) is calculated for the water permeable holes theory.

In the step ten, the theoretical calculated length l of the drainage pipe is calculated by the following formula according to the design number of the water permeable holes, the circumferential distance, the longitudinal distance and the circumferential arrangement range_p。

Theoretically calculating the number of annular holes:

theoretically calculating the number of longitudinal rows:

theoretically calculating the length of the drain pipe:

in the formula_pCalculating the length (m) for the drain pipe theory; d_pDesigning the diameter (m) for the drain pipe; theta_jThe central angle (°) of the drain pipe corresponding to the range of the base; d_sDesigning the diameter (m) for the water permeable holes; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; y is_tCalculating the longitudinal spacing (m) for the water permeable hole theory; z_tThe number of the permeable holes is designed, and the permeable holes are respectively far from two ends

In the eleventh step, the theoretical length l of the drainage pipe is used_pCalculating the design length l of the drain pipe according to the drainage perimeter C of the foundation pit_sNumber of design pipes N_s。

When l is_pAt < 0.5C, N_s＝1，l_sC; when (n-0.5) C is less than l_pN is a positive integer < nC_s＝n，l_s-nC; when nC < l_pIf N is less than (N +0.5) C (N is a positive integer), N is selected_s＝n，l_sWhen the drainage pipe is used, the drainage pipe is required to be perforated at a high rate, and the rigidity of the drainage pipe is required to be improved. Otherwise N_s＝n+1，l_s＝(n+1)C。

In the twelfth step, the design length of the drain pipe and the design total number of the permeable holes are determinedDetermining the circumferential spacing x of the design of the water permeable holes by the following formula_sAnd a longitudinal spacing y_s。

Theoretically calculating the number of annular holes:

theoretically calculating the number of longitudinal rows:

longitudinal design interval:

the adjacent holes in the hoop are arranged in a staggered mode, and the hoop design interval is as follows: x is the number of_s＝2x_t- (formula 12.4) -

Y in the formula_sDesigning longitudinal spacing (m) for the water permeable holes; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; z_tDesigning the number (number) of the water permeable holes; l_sDesigning the length (m) for the drain pipe; d_pDesigning the diameter (m) for the drain pipe; theta_jThe central angle (°) of the drain pipe corresponding to the range of the base; x is the number of_tCalculating the circumferential spacing (m) for the water permeable hole theory; x is the number of_sThe circumferential spacing (m) is designed for the water permeable holes.

Example 4

From the above, the specific operation steps of the present invention are:

step one, substituting relevant parameters into 1.1 to obtain the rainstorm intensity according to the regional rainstorm intensity parameters, the rainfall duration and the design rainstorm reappearance period:

according to the topographic features around the field, the catchment area S is determined to be 36.6hm²And substituting the surface runoff coefficient psi as 0.4 for a related value into 1.2 to obtain the rainwater infiltration flow: q_s＝qS(1-ψ)＝112×36.6×(1-0.4)＝2459.52L/s

Or substituting the related numerical value into 1.3 to obtain the rainwater infiltration flow:

measuring Q for groundwater seepage around field_c367L/s, the permeability influence coefficient lambda is 0.9, and the relevant parameters are substituted into formula 1.4 to obtain the corrected design flow: q_p1＝λ(Q_s+Q_c)＝0.9×(2459.52+367)＝2543.868L/s

Or the related parameters are substituted into the formula 1.5 to obtain the same corrected design flow:

step two, the design diameter of the drain pipe is recorded as d_pDesign water level height is recorded as h_pTheta is shown in FIG. 4_p118 ° and the hydraulic radius R_pHydraulic gradient i_p0.03, pipe wall roughness coefficient n_p＝0.01。

Substituting relevant parameters into the formula 2.1 to obtain the hydraulic radius of the drain pipe:

substituting the relevant parameters into the formula 2.2 to obtain the flow rate of the drainage pipe:

substituting the relevant parameters into the formula 2.3 to obtain the water passing section area of the drain pipe:

substituting the relevant parameters into the water outlet pipe of 2.4Drainage capacity:

or the related parameters are substituted into the formula 2.5 to obtain the drainage capacity of the drainage pipe:

the drainage capacity of the drainage pipe in the third step meets the design flow requirement, namely Q_p2＝Q_p1Substituting the calculation results of formula 1.5 (formula 1.4) and formula 2.5 (formula 2.4) intoThe dp obtained by resolution is 0.788m and is approximately equal to 800mm

Or substituting the relevant parameters into the formula 3.1 to obtain the designed diameter of the drainage pipe:

step four, taking k as 0.1m/s for the permeability coefficient of the backfill soil, and taking i for the osmotic hydraulic gradient_s1, taking the parameters into formula 4.1 to obtain

v_s＝ki_s＝0.1m/s

Step five, simulating the permeable holes into short pipes for calculation, wherein the theoretically calculated diameter of the permeable holes is d_tHydraulic radius of R_tAnd hydraulic slope is uniformly taken i_t0.5, the roughness coefficient of the hole wall is n_t＝0.01。

Obtaining the hydraulic radius of the water permeable hole according to the formula 5.1:

substituting the relevant parameters into 5.2 to obtain the water permeable flow rate of the water permeable hole:

or directly bringing the relevant parameters into formula 5.3 to obtain:

and step six, taking the perforating rate of the drain pipe to be equal to 0.1, and taking the calculation results of the formulas 4.1 and 5.2(5.3) into the formulaTo obtain

Design diameter d of water-permeable hole according to engineering experience_s＝10mm

Seventhly, uniformly taking i from the water permeable holes through hydraulic gradient_t0.5, the roughness coefficient of the hole wall is n_tD is taken as the design diameter of the water permeable hole which is 0.01_sThe effective coefficient of the water permeable hole is normally xi 0.7.

Substituting the relevant parameters into 7.1 to obtain the hydraulic radius of the water permeable hole

Substituting the relevant parameters into 7.2 to obtain the design flow rate of the water permeable hole

Or bringing the relevant parameters into 7.3 directly to obtain the design flow rate of the water permeable hole

Substituting the relevant parameters into 7.4 to obtain the water cross-sectional area of a single water permeable hole

Substituting the relevant parameters into 7.5 to obtain the water permeability Q of a single water permeable hole_td＝1000F_tv_s＝1000×0.0000785×1.3＝0.102L/s

Substituting the relevant parameters into 7.6 to obtain all water permeable poresWater capacity Q_tz＝ξZ_tQ_td＝0.7×0.102Z_t＝0.0714Z_t

Or directly substituting the relevant parameters into 7.7 to obtain the water permeability of all water permeable holes

Step eight, the water permeability should meet the design flow, namely Q_tz＝Q_p1Substituting the formula 7.6(7.7) and the formula 1.5 to obtain

Or substituting the relevant parameters into the formula 8.1

Step nine, taking the hole punching rate of the water permeable hole as mu-0.1, and taking the design diameter as d_s0.01, substituting the relevant parameters into formula 9.3 and formula 9.4

Step ten, arranging water permeable holes above the base in the pipeline range shown in figures 4 and 5, wherein the corresponding central angle is 360-theta_j，θ_jCalculating the circumferential distance x by the water permeable hole theory as 90_tTheoretical calculation of longitudinal spacing y ═ 0.028_t0.028, designing the number of water permeable holes Z_tDesign drain pipe diameter d 35628_p0.8m, the diameter d of the water permeable hole_s＝0.01。

Substituting the relevant parameters into formula 10.1 to calculate the number of annular holes theoretically:

substituting the relevant parameters into formula 10.2 to calculate the longitudinal row number:

the length of the drain pipe is calculated by substituting related parameters into formula 10.3:

eleven, taking C-1123 m, l of the drainage perimeter of the foundation pit_pLess than 0.5C, so the number of the drain pipes N_s1, the actual length l of the drain pipe_s＝1123m。

Twelfth, the range of the pipeline with the water permeable holes arranged above the base is shown in the figures 4 and 5, and the corresponding central angle is 360-theta_j，θ_jCalculating the circumferential distance x by the water permeable hole theory as 90_tTheoretical calculation of longitudinal spacing y ═ 0.028_t0.028, designing the number of water permeable holes Z_tDesign drain pipe diameter d 35628_p0.8m, the diameter d of the water permeable hole_s0.01, the design length of the drain pipe is l_s＝1123。

Substituting the relevant parameters into formula 12.1 to calculate the number of annular holes in theory:

substituting the relevant parameters into formula 12.2 to calculate the longitudinal row number:

substituting the relevant parameters into the formula 12.3 to obtain the longitudinal design interval:

the annular adjacent holes are arranged in a staggered mode, and relevant parameters are substituted into a formula 12.4 to obtain the annular design interval:

x_s＝2×0.028＝0.056m＝56mm 。