阅读说明：本技术 一种流沙地层立体式降水方法 (Three-dimensional dewatering method for quicksand stratum ) 是由 何永义 王明年 孙伯乐 杜英杰 隋文忠 李凯 于丽 刘大刚 陈平 申超超 薛瑞 于 2021-04-13 设计创作，主要内容包括：本发明涉及一种流沙地层立体式降水方法,包括步骤：在流沙地层地貌进行隧道施工过程中,针对隧道掌子面和隧顶,采用真空负压降水方法进行降水,针对隧道底部,采用重力式降水井降水方法进行降水。通过本发明,能够有效解决掌子面涌砂及底板砂沸现象,很好的控制地下水位线低于仰拱施工最低点,克服了富水流沙地层仰拱施工困难的问题。通过本发明,能够有效解决掌子面涌砂及底板砂沸现象,很好的控制地下水位线低于仰拱施工最低点,克服了富水流沙地层仰拱施工困难的问题。(The invention relates to a three-dimensional dewatering method for a quicksand stratum, which comprises the following steps: in the process of tunnel construction of quicksand stratum landforms, a vacuum negative pressure precipitation method is adopted for precipitation of tunnel face surfaces and tunnel tops, and a gravity type precipitation well precipitation method is adopted for precipitation of tunnel bottoms. By the aid of the method, sand gushing on the tunnel face and sand boiling of the bottom plate can be effectively avoided, the underground water level is well controlled to be lower than the lowest point of inverted arch construction, and the problem of difficulty in inverted arch construction of a water-rich quicksand stratum is solved. By the aid of the method, sand gushing on the tunnel face and sand boiling of the bottom plate can be effectively avoided, the underground water level is well controlled to be lower than the lowest point of inverted arch construction, and the problem of difficulty in inverted arch construction of a water-rich quicksand stratum is solved.)

1. A three-dimensional dewatering method for a quicksand stratum is characterized by comprising the following steps:

in the process of tunnel construction of quicksand stratum landforms, a vacuum negative pressure precipitation method is adopted for precipitation of tunnel face surfaces and tunnel tops, and a gravity type precipitation well precipitation method is adopted for precipitation of tunnel bottoms.

2. A method for three-dimensional precipitation of a quicksand formation according to claim 1, characterised in that the steps of vacuum negative pressure precipitation method comprise:

arranging parameters on the precipitation section according to requirements, adopting red paint positioning marks on drilling point positions and intervals according to design, and preparing hole positions influencing drilling in advance;

an XY-2B type geological drilling machine is adopted, and a drilling machine base is modified into a hydraulic system base capable of moving transversely and longitudinally; after the debugging operation is finished, the direction and the angle of the drill rod are adjusted according to the design by the alignment point position;

the drilling hole is formed by pressing water with a hydraulic water pump through the center of a drill rod in an impacting manner, the disturbance to the position of the hole opening is large, the hydraulic water cannot be closed when a hole-forming lower pipe retreats from the drill rod, and the hydraulic water is closed when the hole opening is 1 meter;

after drilling is finished, the drill is not withdrawn, the downcomer is inserted through the middle of the hollow drill rod, then the downcomer is withdrawn slowly, and the downcomer is left in the drill hole;

arranging a main pipe and branch pipes, wherein the main pipe is made of phi 80mm steel pipes, branch pipe connectors are arranged along a pipe body at an interval of 0.2m, the branch pipes are connected with the main pipe through 32mm steel wire hoses, valves are additionally arranged at the connection parts to control the precipitation of well pipes, the main pipe is divided into sections of every 1.5m, one end of each pipe is firmly sealed and welded through 8mm steel plates, one end of each pipe is connected with a vacuum pump through the phi 80mm steel wire hoses, and the vacuum pump is suspended on two side walls or a middle operation surface which is about 1.5m away from the operation surface and is placed and fixed in order;

pulling out a branch pipe segment wood plug connected with the main pipe, connecting the branch pipe with the well point pipe, adopting 10# lead wire for binding firmly, and winding tightly by using a sealing adhesive tape;

checking the connection condition of each pipe;

performing trial pumping before formal operation of pumping to check whether the pumping equipment operates normally or not and whether the pipeline has an air leakage phenomenon or not, and ensuring continuous pumping after confirming that no abnormal phenomena such as water leakage, air leakage and the like exist;

in order to keep continuous precipitation, a dual power supply is required to be used for preventing power failure; the water outlet rule is 'big first then small, muddy first then clear', and the water quantity, water level and vacuum degree are observed at fixed time in the process.

3. The stereoscopic dewatering method for the quicksand stratum according to claim 2, wherein each 9m dewatering pipe is formed by binding and welding each section of 1.5m long steel pipe in a segmented manner; drilling 8mm holes on the pipe body, arranging the pipe body in a quincunx shape at intervals of 10cm, and drilling holes without precipitation in sections of 2m of the pipe end and 0.5m of the pipe head; after drilling of each section of pipe, wrapping two layers of the pipe by adopting geotextile, wrapping one layer of a 100-mesh filter screen outside, and tightly binding the pipe by adopting binding wires at intervals of 20cm after wrapping; the phi 32mm precipitation steel pipe adopts 25 steel pipes as joints of each section of pipe, and is connected by welding; each downcomer is provided with a pipe head with a special structure, the length of the pipe head is 10cm, and the bottom end of the pipe head adopts a phi 8mm steel bar welding crosshead and is sealed.

4. A method of stereoscopic precipitation of a quicksand formation as claimed in claim 2 wherein the step of performing a test pump prior to the step of operating the pump formally comprises:

after all pipelines are connected, starting a vacuum pump to exhaust, starting a water suction pump to test water suction, checking whether each joint of a rubber pipe connected with a water collecting main pipe and a well point pipe has an air leakage phenomenon during test water suction, finding that the phenomenon needs to be reconnected or blocked by oil putty, and wound by a sealing adhesive tape, and screwing the flange plate bolt and the lead wire of the rubber pipe again until the air leakage does not occur;

a vacuum gauge is arranged on a water inlet pipe of the water pump, and a pressure gauge is arranged on a water outlet pipe of the water pump; in order to observe whether the precipitation depth reaches the precipitation depth required by design, an observation well point is arranged at the center of the foundation pit so as to measure the water level through the observation well point and draw out a precipitation curve; when trying to pump, the vacuum degree of the whole pipe network is checked and should reach above 60kPa, and formal water pumping can be carried out.

5. The stereoscopic dewatering method for a quicksand formation of claim 1, wherein the gravity dewatering well dewatering method comprises the following steps:

drilling a well hole of the dewatering well according to a preset well position plane layout diagram;

prefabricating a dewatering well, putting the prefabricated dewatering well into a corresponding well hole, and simultaneously burying a protective cylinder of the dewatering well;

filling crushed stone into the dewatering well, measuring the filling height of the crushed stone in real time, and sealing the well mouth of the dewatering well by bentonite until the paper crushed stone is lowered to a preset position;

when the filling is finished, a chemical agent soaking air-blowing method and a piston pumping and discharging method are adopted for well washing;

after the construction of the dewatering well is finished, the deep well pump is timely put in, a drainage pipeline and a cable are laid, after the water pumping and drainage system is installed, the water pumping is carried out by adopting the dead weight type dewatering water pumping method, and the water level is reduced by adopting the deep well pump water pumping method.

6. The stereoscopic dewatering method for a quicksand formation of claim 5, wherein the dewatering well comprises:

the casing pipe adopts a bridge type steel pipe; one end of the casing pipe is fixedly connected with one end of a filter pipe, the filter pipe is a pipe body with the outer side sequentially coated with geotextile and a 100-mesh nylon gauze, and the pipe diameter is the same as that of the casing pipe; the other end of the filter pipe is fixedly connected with a settling pipe, the diameter of the settling pipe is the same as that of the casing pipe, and the bottom opening is sealed.

7. A stereoscopic dewatering method for a quicksand formation according to claim 5, further comprising the step of cleaning and replacing slurry before the step of placing the prefabricated dewatering well into the corresponding well hole, and specifically comprising:

before the drill is lifted, the drill rod is lifted to be 0.50m away from the bottom of the hole, impurities in the hole are removed, the density of slurry in the hole is adjusted to 1.05 step by step, the sediment at the bottom of the hole is less than 30cm, and the returned slurry does not contain mud blocks.

8. The three-dimensional dewatering method for the quicksand stratum as claimed in claim 6, wherein the depth of the hole is measured before the well is lowered, the well is lowered after the depth of the hole meets the design requirement, and a set of centralizers with the diameter less than 5cm is respectively arranged at the upper end and the lower end of the strainer to ensure that the strainer can be centered; after the design depth is reached, the wellhead is fixed and centered; the process of lowering the well pipe is continuously carried out, the well pipe cannot be stopped in the middle, if the hole collapses or the sediment is too thick due to mechanical failure and the like, the well pipe is pulled out, the hole is swept, the hole is lowered again after hole cleaning, and the well pipe is strictly forbidden to be forcibly inserted into the bottom of the collapsed hole.

9. A stereoscopic dewatering method for a quicksand stratum as claimed in claim 5, wherein the depth inside and outside the dewatering well is measured by a measuring rope before filling the crushed rock material, the difference between the depth and the inside of the dewatering well is not more than the length of the settling pipe, and the height of the crushed rock material is measured along with the filling of the crushed rock material in the process of filling the crushed rock material; the working procedure of filling the crushed stone is continuously carried out, and the midway is not terminated until the crushed stone is put into a preset position; the amount of the filter material which is finally put into is not less than the calculated amount.

10. A three-dimensional dewatering method for a quicksand stratum as claimed in claim 5, wherein when the bentonite is used for sealing holes, in order to prevent bridging during the confining filling, the bentonite is made into mud balls of 1 cm-3 cm before the confining filling; and (3) controlling the running-in speed and the single filling amount during the enclosing filling, enclosing and filling along the periphery of the dewatering well casing pipe according to the principle of slow down, and then performing sealing work outside the wellhead.

Technical Field

The invention relates to the technical field of engineering dewatering construction, in particular to a three-dimensional dewatering method for a quicksand stratum.

Background

The third series of fine sandstone strata soft rock has loose rock quality and extremely poor diagenesis, belongs to extremely soft rock, has poor stability and is easy to soften when meeting water; when groundwater develops or the water content is high, the phenomenon of softening surrounding rock is obvious, sandstone is mostly silt-shaped, the phenomenon of water gushing occurs at the base, the water is soaked into silt, and collapse and block falling of the arch part and the side wall are serious.

The tunnel is along with advancing the constantly increase of hole degree of depth, and the volume of gushing water also constantly increases, and when the water yield reached more than 500 m/d, the reinforcement measure that the quicksand stratum taken was fairly complicated to hardly satisfy the needs of construction, the construction progress received serious restriction, owing to receive the infiltration influence, the original state sandstone worsens rapidly, often appears the quicksand form and gushes outward, and the construction risk is great, carries out precipitation to the face before the construction and handles very necessarily.

Disclosure of Invention

In order to solve the technical problem, the invention provides a three-dimensional dewatering method for a quicksand stratum.

The invention provides a three-dimensional dewatering method for a quicksand stratum, which comprises the following steps:

in the process of tunnel construction of quicksand stratum landforms, a vacuum negative pressure precipitation method is adopted for precipitation of tunnel face surfaces and tunnel tops, and a gravity type precipitation well precipitation method is adopted for precipitation of tunnel bottoms.

The vacuum negative pressure precipitation method comprises the following steps:

arranging parameters on the precipitation section according to requirements, adopting red paint positioning marks on drilling point positions and intervals according to design, and preparing hole positions influencing drilling in advance;

an XY-2B type geological drilling machine is adopted, and a drilling machine base is modified into a hydraulic system base capable of moving transversely and longitudinally; after the debugging operation is finished, the direction and the angle of the drill rod are adjusted according to the design by the alignment point position;

the drilling hole is formed by pressing water with a hydraulic water pump through the center of a drill rod in an impacting manner, the disturbance to the position of the hole opening is large, the hydraulic water cannot be closed when a hole-forming lower pipe retreats from the drill rod, and the hydraulic water is closed when the hole opening is 1 meter;

after drilling is finished, the drill is not withdrawn, the downcomer is inserted through the middle of the hollow drill rod, then the downcomer is withdrawn slowly, and the downcomer is left in the drill hole;

arranging a main pipe and branch pipes, wherein the main pipe is made of phi 80mm steel pipes, branch pipe connectors are arranged along a pipe body at an interval of 0.2m, the branch pipes are connected with the main pipe through 32mm steel wire hoses, valves are additionally arranged at the connection parts to control the precipitation of well pipes, the main pipe is divided into sections of every 1.5m, one end of each pipe is firmly sealed and welded through 8mm steel plates, one end of each pipe is connected with a vacuum pump through the phi 80mm steel wire hoses, and the vacuum pump is suspended on two side walls or a middle operation surface which is about 1.5m away from the operation surface and is placed and fixed in order;

and (3) pulling out the branch pipe segment wood plug connected with the main pipe, connecting the branch pipe with the well point pipe, firmly binding by adopting 10# lead wires, and tightly winding by using a sealing adhesive tape. Checking the connection condition of each pipe;

performing trial pumping before formal operation of pumping to check whether the pumping equipment operates normally or not and whether the pipeline has an air leakage phenomenon or not, and ensuring continuous pumping after confirming that no abnormal phenomena such as water leakage, air leakage and the like exist;

in order to keep continuous precipitation, a dual power supply is required to be used for preventing power failure; the water outlet rule is 'big first then small, muddy first then clear', and the water quantity, water level and vacuum degree are observed at fixed time in the process.

Wherein each 9m of the downcomer is formed by binding and welding each section of 1.5m long steel pipe in sections; drilling 8mm holes on the pipe body, arranging the pipe body in a quincunx shape at intervals of 10cm, and drilling holes without precipitation in sections of 2m of the pipe end and 0.5m of the pipe head; after drilling of each section of pipe, wrapping two layers of the pipe by adopting geotextile, wrapping one layer of a 100-mesh filter screen outside, and tightly binding the pipe by adopting binding wires at intervals of 20cm after wrapping; the phi 32mm precipitation steel pipe adopts 25 steel pipes as joints of each section of pipe, and is connected by welding; each downcomer is provided with a pipe head with a special structure, the length of the pipe head is 10cm, and the bottom end of the pipe head adopts a phi 8mm steel bar welding crosshead and is sealed.

Wherein, the step of trying to draw water before formally operating to draw water includes:

after all pipelines are connected, starting a vacuum pump to exhaust, starting a water suction pump to test water suction, checking whether each joint of a rubber pipe connected with a water collecting main pipe and a well point pipe has an air leakage phenomenon during test water suction, finding that the phenomenon needs to be reconnected or blocked by oil putty, and wound by a sealing adhesive tape, and screwing the flange plate bolt and the lead wire of the rubber pipe again until the air leakage does not occur;

a vacuum gauge is arranged on a water inlet pipe of the water pump, and a pressure gauge is arranged on a water outlet pipe of the water pump; in order to observe whether the precipitation depth reaches the precipitation depth required by design, an observation well point is arranged at the center of the foundation pit so as to measure the water level through the observation well point and draw out a precipitation curve; when trying to pump, the vacuum degree of the whole pipe network is checked and should reach above 60kPa, and formal water pumping can be carried out.

The gravity type precipitation well precipitation method comprises the following steps:

drilling a well hole of the dewatering well according to a preset well position plane layout diagram;

prefabricating a dewatering well, putting the prefabricated dewatering well into a corresponding well hole, and simultaneously burying a protective cylinder of the dewatering well;

filling crushed stone into the dewatering well, measuring the filling height of the crushed stone in real time, and sealing the well mouth of the dewatering well by bentonite until the paper crushed stone is lowered to a preset position;

when the filling is finished, a chemical agent soaking air-blowing method and a piston pumping and discharging method are adopted for well washing;

after the construction of the dewatering well is finished, the deep well pump is timely put in, a drainage pipeline and a cable are laid, after the water pumping and drainage system is installed, the water pumping is carried out by adopting the dead weight type dewatering water pumping method, and the water level is reduced by adopting the deep well pump water pumping method.

Wherein, precipitation well includes:

the casing pipe adopts a bridge type steel pipe; one end of the casing pipe is fixedly connected with one end of a filter pipe, the filter pipe is a pipe body with the outer side sequentially coated with geotextile and a 100-mesh nylon gauze, and the pipe diameter is the same as that of the casing pipe; the other end of the filter pipe is fixedly connected with a settling pipe, the diameter of the settling pipe is the same as that of the casing pipe, and the bottom opening is sealed.

Wherein, before the step of putting the prefabricated precipitation well into the corresponding well hole, still include the step of clear hole trades thick liquid, specifically include:

before the drill is lifted, the drill rod is lifted to be 0.50m away from the bottom of the hole, impurities in the hole are removed, the density of slurry in the hole is adjusted to 1.05 step by step, the sediment at the bottom of the hole is less than 30cm, and the returned slurry does not contain mud blocks.

Before descending the well, measuring the depth of the hole, and after the depth of the hole meets the design requirement, starting descending the well, and arranging a set of centralizers with the diameter less than 5cm at the upper end and the lower end of the strainer respectively to ensure that the strainer can be centered; after the design depth is reached, the wellhead is fixed and centered; the process of lowering the well pipe is continuously carried out, the well pipe cannot be stopped in the middle, if the hole collapses or the sediment is too thick due to mechanical failure and the like, the well pipe is pulled out, the hole is swept, the hole is lowered again after hole cleaning, and the well pipe is strictly forbidden to be forcibly inserted into the bottom of the collapsed hole.

Before filling the crushed stone, measuring the depth inside and outside the dewatering well by using a measuring rope, wherein the difference between the depth and the depth does not exceed the length of the settling pipe, and the height of the crushed stone is measured along with the filling in the process of filling the crushed stone; the working procedure of filling the crushed stone is continuously carried out, and the midway is not terminated until the crushed stone is put into a preset position; the amount of the filter material which is finally put into is not less than the calculated amount.

Wherein, when the bentonite is adopted for hole sealing, in order to prevent the bridging phenomenon from generating during the enclosing and filling, the bentonite is made into mud balls of 1 cm-3 cm before the enclosing and filling; and (3) controlling the running-in speed and the single filling amount during the enclosing filling, enclosing and filling along the periphery of the dewatering well casing pipe according to the principle of slow down, and then performing sealing work outside the wellhead.

Different from the prior art, the three-dimensional dewatering method for the quicksand stratum comprises the following steps: in the process of tunnel construction of quicksand stratum landforms, a vacuum negative pressure precipitation method is adopted for precipitation of tunnel face surfaces and tunnel tops, and a gravity type precipitation well precipitation method is adopted for precipitation of tunnel bottoms. By the aid of the method, sand gushing on the tunnel face and sand boiling of the bottom plate can be effectively avoided, the underground water level is well controlled to be lower than the lowest point of inverted arch construction, and the problem of difficulty in inverted arch construction of a water-rich quicksand stratum is solved.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic flow chart of a vacuum negative pressure precipitation method in a three-dimensional precipitation method for a quicksand stratum provided by the invention.

FIG. 2 is a schematic structural diagram of a downcomer in a three-dimensional dewatering method for a quicksand formation according to the present invention.

FIG. 3 is a schematic flow chart of a gravity type precipitation well precipitation method in the three-dimensional precipitation method for the quicksand stratum provided by the invention.

FIG. 4 is a schematic structural view of a well casing in a three-dimensional method for dewatering a quicksand formation according to the present invention.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The invention provides a three-dimensional dewatering method for a quicksand stratum, which comprises the following steps:

in the process of tunnel construction of quicksand stratum landforms, a vacuum negative pressure precipitation method is adopted for precipitation of tunnel face surfaces and tunnel tops, and a gravity type precipitation well precipitation method is adopted for precipitation of tunnel bottoms.

As shown in fig. 1, the steps of the vacuum negative pressure precipitation method include:

arranging parameters on the precipitation section according to requirements, adopting red paint positioning marks on drilling point positions and intervals according to design, and preparing hole positions influencing drilling in advance;

an XY-2B type geological drilling machine is adopted, and a drilling machine base is modified into a hydraulic system base capable of moving transversely and longitudinally; after the debugging operation is finished, the direction and the angle of the drill rod are adjusted according to the design by the alignment point position;

the drilling hole is formed by pressing water with a hydraulic water pump through the center of a drill rod in an impacting manner, the disturbance to the position of the hole opening is large, the hydraulic water cannot be closed when a hole-forming lower pipe retreats from the drill rod, and the hydraulic water is closed when the hole opening is 1 meter;

after drilling is finished, the drill is not withdrawn, the downcomer is inserted through the middle of the hollow drill rod, then the downcomer is withdrawn slowly, and the downcomer is left in the drill hole;

arranging a main pipe and branch pipes, wherein the main pipe is made of phi 80mm steel pipes, branch pipe connectors are arranged along a pipe body at an interval of 0.2m, the branch pipes are connected with the main pipe through 32mm steel wire hoses, valves are additionally arranged at the connection parts to control the precipitation of well pipes, the main pipe is divided into sections of every 1.5m, one end of each pipe is firmly sealed and welded through 8mm steel plates, one end of each pipe is connected with a vacuum pump through the phi 80mm steel wire hoses, and the vacuum pump is suspended on two side walls or a middle operation surface which is about 1.5m away from the operation surface and is placed and fixed in order;

pulling out a branch pipe segment wood plug connected with the main pipe, connecting the branch pipe with the well point pipe, adopting 10# lead wire for binding firmly, and winding tightly by using a sealing adhesive tape; checking the connection condition of each pipe;

performing trial pumping before formal operation of pumping to check whether the pumping equipment operates normally or not and whether the pipeline has an air leakage phenomenon or not, and ensuring continuous pumping after confirming that no abnormal phenomena such as water leakage, air leakage and the like exist;

in order to keep continuous precipitation, a dual power supply is required to be used for preventing power failure; the water outlet rule is 'big first then small, muddy first then clear', and the water quantity, water level and vacuum degree are observed at fixed time in the process.

The structure of the downcomer is shown in figure 2, each 9m downcomer is formed by binding and welding each section of 1.5m long steel pipe in sections; drilling 8mm holes on the pipe body, arranging the pipe body in a quincunx shape at intervals of 10cm, and drilling holes without precipitation in sections of 2m of the pipe end and 0.5m of the pipe head; after drilling of each section of pipe, wrapping two layers of the pipe by adopting geotextile, wrapping one layer of a 100-mesh filter screen outside, and tightly binding the pipe by adopting binding wires at intervals of 20cm after wrapping; the phi 32mm precipitation steel pipe adopts 25 steel pipes as joints of each section of pipe, and is connected by welding; each downcomer is provided with a pipe head with a special structure, the length of the pipe head is 10cm, and the bottom end of the pipe head adopts a phi 8mm steel bar welding crosshead and is sealed.

Wherein, the step of trying to draw water before formally operating to draw water includes:

after all pipelines are connected, starting a vacuum pump to exhaust, starting a water suction pump to test water suction, checking whether each joint of a rubber pipe connected with a water collecting main pipe and a well point pipe has an air leakage phenomenon during test water suction, finding that the phenomenon needs to be reconnected or blocked by oil putty, and wound by a sealing adhesive tape, and screwing the flange plate bolt and the lead wire of the rubber pipe again until the air leakage does not occur;

a vacuum gauge is arranged on a water inlet pipe of the water pump, and a pressure gauge is arranged on a water outlet pipe of the water pump; in order to observe whether the precipitation depth reaches the precipitation depth required by design, an observation well point is arranged at the center of the foundation pit so as to measure the water level through the observation well point and draw out a precipitation curve; when trying to pump, the vacuum degree of the whole pipe network is checked and should reach above 60kPa, and formal water pumping can be carried out.

As shown in fig. 3, the gravity precipitation well precipitation method comprises the following steps:

drilling a well hole of the dewatering well according to a preset well position plane layout diagram;

prefabricating a dewatering well, putting the prefabricated dewatering well into a corresponding well hole, and simultaneously burying a protective cylinder of the dewatering well;

filling crushed stone into the dewatering well, measuring the filling height of the crushed stone in real time, and sealing the well mouth of the dewatering well by bentonite until the paper crushed stone is lowered to a preset position;

when the filling is finished, a chemical agent soaking air-blowing method and a piston pumping and discharging method are adopted for well washing;

after the construction of the dewatering well is finished, the deep well pump is timely put in, a drainage pipeline and a cable are laid, after the water pumping and drainage system is installed, the water pumping is carried out by adopting the dead weight type dewatering water pumping method, and the water level is reduced by adopting the deep well pump water pumping method.

Wherein, the structure of precipitation well is as shown in figure 4, includes:

the casing pipe adopts a bridge type steel pipe; one end of the casing pipe is fixedly connected with one end of a filter pipe, the filter pipe is a pipe body with the outer side sequentially coated with geotextile and a 100-mesh nylon gauze, and the pipe diameter is the same as that of the casing pipe; the other end of the filter pipe is fixedly connected with a settling pipe, the diameter of the settling pipe is the same as that of the casing pipe, and the bottom opening is sealed.

In the specific implementation process, the well logging and releasing positions are measured and released according to the well position plane arrangement schematic diagram, and if the well logging and releasing positions encounter obstacles or are influenced by construction conditions in the field construction process, the field can be properly adjusted. The bottom opening of the pile casing is inserted into an undisturbed soil layer, the outside of the pipe is tightly filled by using cohesive soil to prevent the outside of the pipe from returning slurry during construction, and the pile casing part is 0.30m higher than the ground.

The aperture of each opening is phi 290mm, one opening is completely drilled, and when the drilling construction reaches the designed depth, more drilling is carried out for 0.3-0.5 m. Drilling construction description records are made, and in the drilling process, if actual geological conditions are found to be inconsistent with data provided in exploration, designers need to be informed in time, the structure of the well is adjusted in time, and the arrangement position of the water filter pipe can be ensured to be capable of effectively feeding water. The drilling machine is slightly pressed and slowly rotated, the level of the drilling machine is ensured in the drilling process so as to ensure the verticality of the drilled hole, and the hole forming construction adopts the natural slurry making in the hole so as to prevent the hole wall from collapsing.

The hole cleaning and slurry changing work before the well casing is lowered is a key process for ensuring the well quality, and in order to ensure that a formed hole does not form thick mud skin at the position of entering a water-bearing layer, clean water is added for slurry mixing when a drill hole is drilled to the top plate position of the water-bearing layer. After drilling to a designed elevation, lifting the drill rod to be 0.50m away from the bottom of the hole before lifting the drill, removing impurities in the hole, simultaneously gradually adjusting the density of the slurry in the hole to be close to 1.05, wherein the sediment at the bottom of the hole is less than 30cm, and the returned slurry does not contain mud blocks. The first hole cleaning and slurry changing is the key for ensuring the quality of the finished well, and the first hole cleaning and slurry changing directly influences the quality of the finished well, so that the hole cleaning and slurry changing work during construction does not meet the specified requirements and the construction of the next procedure is not allowed to enter.

After the well pipe enters the field, whether the round hole of the filter meets the design requirement or not is checked. The depth must be measured before the pipe is lowered, after the hole depth meets the design requirement, the well pipe is lowered, a set of centralizers (centralizers) with the diameter smaller than the hole diameter of 5cm are respectively arranged at the upper end and the lower end of the strainer pipe during pipe lowering so as to ensure that the strainer pipe can be centered, the well pipe is firmly, vertically and watertight in welding, and after the well pipe is lowered to the design depth, the well mouth is fixed and centered. The process of lowering the well pipe should be continuously carried out, and the well pipe should be stopped in the middle, for example, the well pipe should be pulled out, cleaned and lowered again after the collapse or the excessive deposition caused by mechanical failure, and the like, and the well pipe should be prevented from being forcibly inserted into the bottom of the collapsed hole.

Before filling the crushed stone, the depth inside and outside the well pipe is measured by using a measuring rope, the difference between the depth and the inside of the well pipe should not exceed the length of the settling pipe, and the height of the crushed stone should be measured along with the filling in the process of filling the crushed stone. The process of filling the crushed stone should be continuously carried out, and the process should not be stopped midway until the crushed stone is put into a preset position. The amount of the filter material which is finally input is not less than the calculated amount.

When the bentonite is used for sealing holes, in order to prevent the bridging phenomenon during the enclosing filling, the bentonite is made into mud balls of 1 cm-3 cm before the enclosing filling. And (3) during the enclosing filling, the descending speed and the single filling amount are controlled, and the enclosing filling is carried out along the periphery of the well pipe according to the principle of less slowing. Then the sealing work is done outside the well head.

The well is washed by adopting a chemical agent soaking air-blowing method and a piston pumping method. The well washing is carried out immediately after the well pipe is put down and the filter material is filled, so that the problem that the water seepage effect is influenced because the protective wall mud skin is aged gradually and is difficult to damage after too long time is avoided. It is never allowed to sit for too long or to centrally flush after drilling is completed.

After the well completion construction is finished, a deep well pump is timely put in, drainage pipelines, cables and the like are laid, and after the water pumping and drainage system is installed, water pumping can be started to be tried. The cabling and piping system is installed with care to avoid damage during the pumping process, and therefore, identification is made on these devices in the field.

When the well washing and the precipitation run, water is drained into the water collecting tank by the pipeline, the water is drained into a drainage ditch preset outside the field through the drainage pipeline, and the drainage pipeline preset outside the field is cleaned at regular time to ensure the smoothness of a drainage system.

The submerged dewatering well adopts the method of self-weight dewatering pumping and deep well pumping to reduce the water level, each well uses one deep well pump, and the pumping capacity of the deep well pump is required to be larger than the maximum water yield of the single well.

And after the construction of the dewatering well, the dewatering well is put into operation one well, and the underground water level is reduced in time, so that the tunnel excavation effect is ensured.

Before test operation, the static water level of each well head needs to be measured, and then test operation is started to check whether the pumping equipment and the pumping and draining system can meet the requirement of precipitation.

Before installation, the pump body and the control system should be subjected to comprehensive and careful inspection once. The rotation direction of the motor is checked, whether bolts of each part are screwed up or not, whether lubricating oil is enough or not, whether the sealing of a cable joint is loosened or not, whether a cable is damaged or not and the like are checked, and then the motor can be put into use after rotating on the ground for about 1min if no problem exists. The submersible motor, cables and joints should be reliably insulated and each pump should be provided with a control switch. After the installation, trial water pumping is carried out, and normal work is carried out after the requirement is met.

Through gravity type precipitation well precipitation, no water current gushes out when having realized rich water quicksand stratum tunnel invert excavation, guarantees the clean cleanness of construction face.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.