阅读说明：本技术 输电线路联合板杆单锚板基础结构的下板的设计方法 (Transmission line of electricity combines the design method of the lower plate of plate stem list anchor slab foundation structure ) 是由 李炎隆 雒亿平 于 2019-08-27 设计创作，主要内容包括：本发明公开了输电线路联合板杆单锚板基础结构的下板的设计方法,单锚板基础结构包括板组件、锚杆组件和板柱；板组件包括自上而下设置的上板和下板,板柱位于上板的顶部；锚杆组件包括第一锚杆和第二锚杆,上板和板柱通过第一锚杆固接,上板、下板和板柱通过第二锚杆固接；上板的上表面和/或下表面设置有第一配筋,下板的上表面和/或下表面设置有第二配筋；下板的设计方法：先采用剪切法抗拔计算确定下板尺寸和埋深；再对下板进行抗冲切验算,根据上述确定的下板的尺寸、埋深和抗冲验结果确定下板的配筋数据。本发明可去除下板养护工作,消除了湿作业及现场钢筋绑扎作业,降低了施工周期。(The invention discloses the design methods of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure, and single anchor slab foundation structure includes board group part, anchor rod component and sheet-pile；Board group part includes the upper plate being arranged from top to bottom and lower plate, and sheet-pile is located at the top of upper plate；Anchor rod component includes the first anchor pole and the second anchor pole, and upper plate and sheet-pile are affixed by the first anchor pole, and upper plate, lower plate and sheet-pile are affixed by the second anchor pole；The upper surface and/or lower surface of upper plate are provided with the first arrangement of reinforcement, and the upper surface and/or lower surface of lower plate are provided with the second arrangement of reinforcement；The design method of lower plate: it is first calculated using shearing method resistance to plucking and determines lower board size and buried depth；Punching Shear checking computations are carried out to lower plate again, the arrangement of reinforcement data that result determines lower plate are tested according to the size of the lower plate of above-mentioned determination, buried depth and anti-impact.The present invention can remove lower plate maintenance work, eliminates wet construction and live reinforcing bar binding operation, reduces construction period.)

1. the design method that transmission line of electricity combines the lower plate of plate stem list anchor slab foundation structure, which is characterized in that the list anchor slab base Plinth structure includes board group part, anchor rod component and sheet-pile (5)；

The board group part includes the upper plate (1) being arranged from top to bottom and lower plate (2), and the sheet-pile (5) is located at the upper plate (1) Top；And in the state of constructing completion, the upper plate (1) and lower plate (2) are embedded in underground, and the sheet-pile (5) is extremely Few a part is exposed to ground；

The anchor rod component includes the first anchor pole (3) and the second anchor pole (4), and the upper plate (1) and sheet-pile (5) pass through the first anchor pole (3) affixed, upper plate (1), lower plate (2) and sheet-pile (5) are affixed by the second anchor pole (4)；The upper surface of the upper plate (1) and/or Lower surface is provided with the first arrangement of reinforcement, and the upper surface and/or lower surface of the lower plate (2) are provided with the second arrangement of reinforcement；

The design method of the lower plate, is specifically implemented according to the following steps:

Step 1, it is calculated using shearing method resistance to plucking and determines lower plate (2) size and buried depth；

Step 2, Punching Shear checking computations are carried out to lower plate (2), size, buried depth and the anti-impact of the lower plate (2) determined according to step 1 test knot Fruit determines the arrangement of reinforcement data of lower plate (2).

2. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as described in claim 1, feature It is, the step 1 is specifically implemented according to the following steps:

Step 1.1, using shearing method carry out lower plate (2) on pull out stability Calculation；

Step 1.2, critical buried-depth is obtained according to pulling out stability Calculation in lower plate (2)；

Step 1.3, determine the buried depth of lower plate (2) by critical buried-depth according to following condition: the buried depth of lower plate (2) is no more than critical Buried depth.

3. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as claimed in claim 2, feature It is, the step 1.1 is specifically, using stability Calculation is pulled out in following formula (1) progress lower plate (2):

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

In formula (1), γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor pole, R_upFor basic Ultimate Up-lift Bearing Capacity (KN), T_VFor resistance to plucking soil body circular sliding surface shearing resistance upright projection component, G_SIt is self-possessed for the soil body in circular sliding surface, G_{On f}For The self weight of upper plate, G_{Under f}For the self weight of lower plate, G_BackfillFor backfill weight.

4. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as claimed in claim 3, feature It is, the resistance to plucking soil body circular sliding surface shearing resistance upright projection component T_VCalculation formula are as follows:

In formula (2), A₁、A₂For Dimensionless Calculation parameter, by sliding surface form, the internal friction angle of the resistance to plucking soil bodyAnd embedded depth of foundation It is determined than λ；γ_SFor resistance to plucking soil body natural unit weight (kN/m³)；C is soil body cohesive strength；h_tFor lower plate buried depth.

5. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as claimed in claim 3, feature It is, soil body self weight G in the circular sliding surface_SCalculation formula are as follows:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

In formula (3), γ_SFor the natural unit weight (kN/m of the resistance to plucking soil body³), V₀For h_tBasis volume (m in depth bounds³), A₃For nothing Dimension calculating parameter and sliding surface form, internal friction angle by the resistance to plucking soil bodyIt is determined with embedded depth of foundation ratio λ；μ is earth resistance item Reduction coefficient.

6. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as described in claim 1, feature It is, in step 2, the Punching Shear check formula of the lower plate (2) are as follows:

F_l≤0.7β_hpf_ta_m(h-a_s) (4),

In formula (4), β_hpFor by punching bearing capacity influential factor of sectional height；f_tFor concrete tensile strength, a_sTo protect thickness Degree, a_mThe half for the inscribed square side length for being punching failure cone least favorable side oblique section within the scope of foundation's bottom area, h For lower plate thickness.

7. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as described in claim 1, feature It is, in step 2, the data of the arrangement of reinforcement include the moment of flexure of reinforcing bar, the moment of flexure of reinforcing bar is calculated by following formula (5):

In formula (5), M_I、M_IIIt is the moment of flexure of reinforcing bar, B is the diameter of lower plate, and b, b ' are the diameter of steel area, and p is lower plate Average net pressure (kN/m²)。

8. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as claimed in claim 7, feature It is, in step 2, the data of the arrangement of reinforcement include the sectional area of reinforcing bar, calculate both direction tension by following formula (6) The sectional area of power reinforcing bar:

Formula (6), a_sFor protective layer thickness, h is lower plate thickness, f_stFor Steel Bar Tensile Strength；

The steel bar arrangement in the lower plate is carried out according to the sectional area of the reinforcing bar and design specification.

9. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as described in claim 1, feature It is, the lower plate (2) is monolithic reinforced concrete structure.

10. the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure as described in claim 1, feature It is, the ratio of reinforcement of the steel bar stress of the lower plate (2) is not less than 0.15%.

Technical field

The invention belongs to electric power line pole tower equipment technical fields, and in particular to transmission line of electricity combines plate stem list anchor slab basis The design method of the lower plate of structure.

Background technique

Transmission line tower foundation mainly uses " heavy excavation " foundation class, " draw and dig base expanding and base expanding " foundation class, " explosion expanded piling " basis Class.The key dimension of " heavy excavation " foundation class need to be determined according to the resistance to plucking stability requirement of transmission line tower foundation, in order to full The needs of stability are pulled out on foot, it is necessary to increase key dimension, improve foundation cost, simultaneously because spoir is more, to environment It destroys also larger." draw and dig base expanding and base expanding " foundation class is suitable in the anhydrous cohesive soil for penetrating into foundation pit, while pile foundation specification provides, such as Basis uses pile foundation, and essential bearing stratum needs guiding through collapsible loess, therefore the basis is with not being suitable for big thickness collapsible loess Area." explosion expanded piling " foundation class difficulty of construction is larger, has biggish concealment, and complicated construction technique, construction quality are difficult to control It makes, construction quality problem is difficult to find in time, and there is also certain difficulties for detection after work.

To sum up, current transmission line tower foundation structure is primarily present complicated construction technique, and construction quality is not easily-controllable System and the high problem of cost.

Summary of the invention

The object of the present invention is to provide the design methods of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure, solve The problem that the complicated construction technique of transmission line tower foundation structure, construction quality are not easy to control and cost is high.

A kind of technical solution of the present invention is that the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure is set Meter method, single anchor slab foundation structure include board group part, anchor rod component and sheet-pile；

Board group part includes the upper plate being arranged from top to bottom and lower plate, and sheet-pile is located at the top of upper plate, in the shape that construction is completed Under state, upper plate and lower plate are embedded in underground, and at least part of sheet-pile is exposed to ground；

Anchor rod component includes the first anchor pole and the second anchor pole, and upper plate and sheet-pile are affixed by the first anchor pole, upper plate, lower plate and Sheet-pile is affixed by the second anchor pole；The upper surface and/or lower surface of upper plate are provided with the first arrangement of reinforcement, the upper surface of lower plate and/or Lower surface is provided with the second arrangement of reinforcement；

The design method of lower plate, is specifically implemented according to the following steps:

Step 1, it is calculated using shearing method resistance to plucking and determines lower board size and buried depth；

Step 2, Punching Shear checking computations are carried out to lower plate, size, buried depth and the anti-impact of the lower plate determined according to step 1 test result Determine the arrangement of reinforcement data of lower plate.

The features of the present invention also characterized in that:

Step 1, it is specifically implemented according to the following steps:

Step 1.1, using shearing method carry out lower plate on pull out stability Calculation,

Step 1.2, critical buried-depth is obtained according to pulling out stability Calculation in lower plate；

Step 1.3, determine the buried depth of lower plate by critical buried-depth according to following condition: the buried depth of lower plate is buried no more than critical It is deep.

Step 1.1 is specifically, using stability Calculation is pulled out in following formula (1) progress lower plate:

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

In formula (1), γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor pole, R_upFor basic Ultimate Up-lift Bearing Capacity (KN), T_VFor resistance to plucking soil body circular sliding surface shearing resistance upright projection component, G_SIt is self-possessed for the soil body in circular sliding surface, G_{On f}For The self weight of upper plate, G_{Under f}For the self weight of lower plate, G_BackfillFor backfill weight.

Resistance to plucking soil body circular sliding surface shearing resistance upright projection component T_VCalculation formula are as follows:

In formula (2), A₁、A₂For Dimensionless Calculation parameter, by sliding surface form, the internal friction angle of the resistance to plucking soil bodyThe basis and Buried depth ratio λ is determined；γ_SFor resistance to plucking soil body natural unit weight (kN/m³)；C is soil body cohesive strength；h_tFor lower plate buried depth.

Soil body self weight G in circular sliding surface_SCalculation formula are as follows:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

In formula (3), γ_SFor the natural unit weight (kN/m of the resistance to plucking soil body³), V₀For h_tBasis volume (m in depth bounds³), A₃ For Dimensionless Calculation parameter and by sliding surface form, the internal friction angle of the resistance to plucking soil bodyIt is determined with embedded depth of foundation ratio λ；μ is that soil is anti- Power item reduction coefficient.

In step 2, the Punching Shear check formula of lower plate are as follows:

F_l≤0.7β_hpf_ta_m(h-a_s) (4),

In formula (4), β_hpFor by punching bearing capacity influential factor of sectional height；f_tFor concrete tensile strength, a_sFor protection Thickness degree, h are lower plate thickness, a_mBe punching failure cone least favorable side oblique section within the scope of foundation's bottom area it is inscribed just The half of rectangular side length.

In step 2, the data of arrangement of reinforcement include the moment of flexure of reinforcing bar, calculate both direction reinforcing bar by following formula (5) Moment of flexure:

In formula (5), M_I、M_IIIt is the moment of flexure of reinforcing bar, B is the diameter of lower plate, and b, b ' are the diameter of steel area, and p is Lower plate is averaged net pressure (kN/m²)。

In step 2, the data of arrangement of reinforcement include the sectional area of reinforcing bar, calculate both direction tension by following formula (6) The sectional area of power reinforcing bar:

Formula (6), a_sFor protective layer thickness, h is lower plate thickness, f_stFor Steel Bar Tensile Strength；A_sIFor corresponding M_IReinforcing bar cut Area, A_sIIFor corresponding M_IIReinforcing steel area.

Lower plate is monolithic reinforced concrete structure.

The ratio of reinforcement of the steel bar stress of lower plate is not less than 0.15%.

The beneficial effects of the present invention are:

The design method of the lower plate of transmission line of electricity of the present invention joint plate stem list anchor slab foundation structure, through the invention lower plate and Sheet-pile fabricated construction can remove basis lower plate maintenance work, eliminates live reinforcing bar binding operation, reduces construction period； The lower plate of transmission line of electricity that the present invention designs joint plate stem list anchor slab foundation structure have can it is prefabricated and can cast-in-place characteristic, construction letter Just, construction period has been saved, in the work transmission line especially suitable for the poor area of execution conditions；Transmission line of electricity connection of the present invention The design method of the lower plate of plywood bar list anchor slab foundation structure, construction technology is simple, construction quality is controllable, at low cost.

Detailed description of the invention

Fig. 1 is foundation structure in the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure of the present invention Schematic diagram；

Fig. 2 is foundation structure in the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure of the present invention Top view；

Fig. 3 is the knot of the lower plate in the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure of the present invention Structure schematic diagram；

Fig. 4 is lower plate stress in the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure of the present invention Schematic diagram；

When Fig. 5 is that lower plate is pressurized in the design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure of the present invention The simplified schematic diagram of moment of flexure Strength co-mputation.

In figure, 1. upper plates, 2. lower plates, 3. first anchor poles, 4. second anchor poles, 5. sheet-piles, 6. billets.

Specific embodiment

The following describes the present invention in detail with reference to the accompanying drawings and specific embodiments.

The present invention relates to the design methods of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure.

As shown in Figure 1, Figure 2 and Figure 3, single anchor slab foundation structure includes board group part, anchor rod component and sheet-pile 5；Board group part packet The upper plate 1 being arranged from top to bottom and lower plate 2 are included, sheet-pile 5 is located at the top of upper plate 1；And in the state of constructing completion, upper plate 1 and lower plate 2 be embedded in underground, at least part of sheet-pile 5 is exposed to ground；

Anchor rod component includes the first anchor pole 3 and the second anchor pole 4, and upper plate 1 and sheet-pile 5 are affixed by the first anchor pole 3, upper plate 1, Lower plate 2 and sheet-pile 5 are affixed by the second anchor pole 4；The upper surface and/or lower surface of upper plate 1 are provided with the first arrangement of reinforcement, lower plate 2 Upper surface and/or lower surface are provided with the second arrangement of reinforcement；

First anchor pole 3 successively axially penetrates through sheet-pile 5 and upper plate 1, and the both ends of the first anchor pole 3 are logical with upper plate 1 and sheet-pile 5 respectively It is affixed to cross bolt, the second anchor pole 4 be arranged in sheet-pile 5, one end of the second anchor pole 4 successively axially penetrate through upper plate 1, lower plate 2 and with Lower plate 2 is affixed by bolt；The both ends of first anchor pole 3 are equipped with billet 6, and one of billet 6 is arranged in bolt and plate Between column 5, another billet 6 is arranged between bolt and upper plate 1, and one end of the second anchor pole 4 is equipped with billet 6, billet 6 One end be arranged between bolt and lower plate 2；Between first anchor pole 3 and billet 6 on the second anchor pole 4 and the bolt closed on Equipped with gasket.

The design method of the lower plate of transmission line of electricity joint plate stem list anchor slab foundation structure of the present invention, specifically according to the following steps Implement:

Step 1, it is calculated using shearing method resistance to plucking and determines lower board size and buried depth；

Step 2, Punching Shear checking computations are carried out to lower plate, size, buried depth and the anti-impact of the lower plate determined according to step 1 test result Determine the arrangement of reinforcement data of lower plate.

Further, step 1 is specifically implemented according to the following steps:

Step 1.1, using shearing method carry out lower plate on pull out stability Calculation；

Step 1.2, critical buried-depth is obtained according to pulling out stability Calculation in lower plate；

Step 1.3, determine the buried depth of lower plate by critical buried-depth according to following condition: the buried depth of lower plate is buried no more than critical It is deep.

Wherein, step 1.1 is specifically, using stability Calculation is pulled out in following formula (1) progress lower plate:

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

In formula (1), γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor pole, R_upFor basic Ultimate Up-lift Bearing Capacity (KN), T_VFor resistance to plucking soil body circular sliding surface shearing resistance upright projection component, G_SIt is self-possessed for the soil body in circular sliding surface, G_{On f}For The self weight of upper plate, G_{Under f}For the self weight of lower plate, G_BackfillFor backfill weight.

Resistance to plucking soil body circular sliding surface shearing resistance upright projection component T_VCalculation formula are as follows:

In formula (2), A₁、A₂For Dimensionless Calculation parameter, by sliding surface form, the internal friction angle of the resistance to plucking soil bodyThe basis and Buried depth ratio λ is determined；γ_SFor resistance to plucking soil body natural unit weight (kN/m³)；C is soil body cohesive strength；h_tFor lower plate buried depth.

Soil body self weight G in circular sliding surface_SCalculation formula are as follows:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

In formula (3), γ_SFor the natural unit weight (kN/m of the resistance to plucking soil body³), V₀For h_tBasis volume (m in depth bounds³), A₃ For Dimensionless Calculation parameter and by sliding surface form, the internal friction angle of the resistance to plucking soil bodyIt is determined with embedded depth of foundation ratio λ；μ is that soil is anti- Power item reduction coefficient.

In step 2, the Punching Shear check formula of lower plate are as follows:

F_l≤0.7β_hpf_ta_m(h-a_s) (4),

In formula (4), β_hpAs h≤0.8m, to take 1.0 by punching bearing capacity influential factor of sectional height, as h >=2.0m, 0.9 is taken, is taken therebetween by linear interpolation；f_tFor concrete tensile strength, C35 concrete, f are generally used_tTake 2.2N/ mm²；a_sFor protective layer thickness, h is lower plate thickness, a_mIt is punching failure cone least favorable side oblique section in foundation's bottom area model The half of inscribed square side length in enclosing.

In step 2, the data of arrangement of reinforcement include the moment of flexure of reinforcing bar, calculate both direction reinforcing bar by following formula (5) Moment of flexure:

In formula (5), M_I、M_IIIt is the moment of flexure of reinforcing bar, B is the diameter of lower plate, and b, b ' are the diameter of steel area, and p is Lower plate is averaged net pressure (kN/m²)。

In step 2, the data of arrangement of reinforcement include the sectional area of reinforcing bar, calculate both direction tension by following formula (6) The sectional area of power reinforcing bar:

Formula (6), a_sFor protective layer thickness, h is lower plate thickness, f_stFor Steel Bar Tensile Strength；A_sIFor corresponding M_IReinforcing bar cut Area, A_sIIFor corresponding M_IIReinforcing steel area.

Further, lower plate is monolithic reinforced concrete structure；The ratio of reinforcement of the steel bar stress of lower plate is not less than 0.15%.

A kind of design method of the lower plate of the double anchor slab foundation structures of present invention transmission line of electricity joint plate stem is carried out below detailed It describes in detail bright.

(1) it is calculated using shearing method resistance to plucking and determines lower board size and buried depth

Due to the presence of horizontal force, on the basis of pull out when, anchor pole can provide the power of certain antidumping for basic upper plate, often Pulling force on root anchor pole are as follows: T '；The lower plate on joint plate rope basis is calculated using shearing method and pulls out stabilization, due to plate rope commbined foundations Special shape and difficulty and economy in view of construction, lower plate should shallow embedding as far as possible, i.e. lower plate buried depth is not more than critical buried-depth.

Therefore only exist h_t≤h_cThe case where, then according to specification " DL/T 5219-2005 aerial power transmission line basic engineering skill Art provides " calculated with shearing method when pulling out stable should be carried out using following formula (1) lower plate on pull out stability Calculation:

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

In formula (1), γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor pole, R_upFor basic Ultimate Up-lift Bearing Capacity (KN), T_VFor resistance to plucking soil body circular sliding surface shearing resistance upright projection component, G_SIt is self-possessed for the soil body in circular sliding surface, G_{On f}For The self weight of upper plate, G_{Under f}For the self weight of lower plate, G_BackfillFor backfill weight.

On the basis of when pulling out additional partial safety factor it is as shown in table 1:

Table 1, on the basis of additional partial safety factor when pulling out

G in formula (1)_{On f}、G_{Under f}、G_BackfillIt is calculated as follows respectively:

G_{On f}=γ_ConcreteV_{Upper plate} (101)

G_{Under f}=γ_ConcreteV_{Lower plate} (102)

G_Backfill=γ_Backfillπr_Hole ²h_t (103)

Formula (101), (102), in (103), γ_ConcreteFor concrete density (kN/m³)；V_{Upper plate}For upper plate volume (m³)；V_{Lower plate}For under Plate bulk (m³)；γ_BackfillFor backfill bulk density, natural rock-filled bulk density can be reduced according to backfill coefficient, it is proposed that take 0.8 γ_S (kN/m³)；r_HoleFor lower panel aperture (m).

Power transmission tower is corner tower, γ_fIt can be taken as 1.6 according to table 1, uplift force T '=556kN that lower plate is subject to.

Resistance to plucking soil body circular sliding surface shearing resistance upright projection component T_VCalculation formula are as follows:

In formula (2), A₁、A₂For Dimensionless Calculation parameter, by sliding surface form, the internal friction angle of the resistance to plucking soil bodyThe basis and Buried depth ratio λ is determined；γ_SFor resistance to plucking soil body natural unit weight (kN/m³)；C is soil body cohesive strength；h_tFor lower plate buried depth.

Wherein,

Wherein, α is intermediate computations parameter, indicates the feature that radius r changes with basic aspect ratio λ (h/D)；

Wherein, n is resistance to plucking soil mass sliding surface morphological parameters, different with the physico mechanical characteristic variation of the soil body, can be according to examination Determination is tested, clay preferably takes n=4, and sandy soil preferably takes n=2~3, and it is that lower plate is straight that Gobi desert rubble local product, which takes n=1.0~1.5, D, Diameter.

Soil body self weight G in circular sliding surface_SCalculation formula are as follows:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

In formula (3), γ_SFor the natural unit weight (kN/m of the resistance to plucking soil body³), V₀For h_tBasis volume (m in depth bounds³), A₃ For Dimensionless Calculation parameter and by sliding surface form, the internal friction angle of the resistance to plucking soil bodyIt is determined with embedded depth of foundation ratio λ；μ is that soil is anti- Power item reduction coefficient.

Earth resistance item reduction coefficient calculation method is as follows:

1. as L >=D+2 λ h₁When, μ=1.00；

2. as L=D, if h_tWhen≤2.5D, μ=0.75；If 2.5D≤h_tWhen≤3.0D, μ=0.65；If 3.0D≤h_t When≤4.0D, μ=0.55；

3. as D < L < D+2 λ h₁When, μ can be determined according to interpolation method；

In above formula, λ is related coefficient with adjacent resistance to plucking soil body shear force face,When, λ=0.50； When, λ=0.55；When, λ=0.60； When, λ=0.65；

Other values can be obtained by interpolation.

Wherein, A₁、A₂And A₃Value mainly by buried depth ratio h_t/ B control, therefore, the case where design can be according to different buried depth ratio Lower board size and arrangement of reinforcement are designed, and carries out pulling out Stability Checking Calculation in lower plate.The critical depth of various soil mass is as shown in table 2:

The critical depth of table 2, various soil mass

Be enumerated the critical depth of different soil in table 2, when geological conditions is cohesive soil, critical depth between 3.5D~ Between 1.5D, therefore, when according to different buried depth than design lower plate, to make basic lower plate meet the requirement of shallow embedding, design when institute The buried depth ratio of selection should be less than defined critical buried-depth ratio.It is contemplated that the dosage and buried depth of basic material are to soil body resistance to plucking Influence, the size of lower plate again cannot excessive and buried depth it is also unsuitable too small, this just determines that buried depth ratio cannot be too small.

Because being designed as the design on single basis, do not consider by horizontal force and adjacent foundation to power transmission tower upper and low approximations Reduction, since lower plate carries out angle θ=90 °, then it is 1.0 that lower plate, which allows upper and low approximations reduction factor,.

Allow upper and low approximations R_up:

γ_fT ' < R_up(302),

In formula (302), γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor pole.

(2) basic lower plate Punching Shear checking computations

Joint plate rope basis lower plate stress is as shown in figure 4, lower plate stress is axial tension, but is individually directed to lower plate to examine When worry, lower plate actual force is to act on lower plate bottom direction to upward pressure in fact, and size is T '.

The Punching Shear of lower plate is checked according to specification " DL/T 5219-2005 aerial power transmission line basic engineering technical stipulation " Following formula is calculated:

F_l≤0.7β_hpf_ta_m(h-a_s) (4)

In formula (4), β_hpAs h≤0.8m, to take 1.0 by punching bearing capacity influential factor of sectional height, as h >=2.0m, 0.9 is taken, is taken therebetween by linear interpolation, f_tFor concrete tensile strength, C35 concrete, f are generally used_tTake 1.57N/ mm²；a_sFor protective layer thickness, 50mm is taken.

Wherein,

In formula (401), a_bBe punching failure cone least favorable side oblique section within the scope of foundation's bottom area it is inscribed just Rectangular side length.

F_l=pA_l (402)

In formula (402), p is that lower plate is averaged net pressure (kN/m²)；A_lFor Punching Shear shaded area (m²)。

Wherein, the lower plate net pressure design value p that is averaged is calculated according to following formula:

In formula (403), r_{Lower plate}For lower plate radius (m)；T ' is the pulling force on every anchor pole, a_sFor protective layer thickness.

Punching Shear shaded area A_lIt is calculated according to following formula:

According to the size being calculated, the diameter of lower plate is B, the thickness h of lower plate, can be in the hope of:

F_l≤0.7β_hpf_ta_m(h-a_s) (405),

(3) lower plate Reinforcement Design

Lower plate arrangement of reinforcement is calculated according to the buried depth and lower board size that are calculated.

The load that power transmission tower basis lower plate is subject to is axial load, as shown in figure 5, since lower plate is circle, Gu Xiabanding The moment of flexure of face both direction can size it is identical, and can according to " DL/T 5219-2005 aerial power transmission line basic engineering technology advise Following formula Conservative estimation in calmly ".

In formula (5), b, b ' can be determined according to above and Fig. 5.

After obtaining moment of flexure, the tension reinforcement sectional area of both direction can be calculated according to the following formula:

It, need to be according to calculated reinforcing steel area and " GB 50007- after calculating basic lower plate tension reinforcement area of section 2011 Code for design of building " in about lower plate steel bar arrangement technical stipulation carry out power transmission tower joint plate rope basis The steel bar arrangement of upper plate.

(1) the steel bar stress minimum steel ratio of lower plate is no less than 0.15%, and the minimum diameter of lower plate steel bar stress is unsuitable Less than 10mm, spacing is not preferably greater than 200mm, is not also preferably less than 100mm；The thickness of cover to reinforcement takes 50mm；

(2) as diameter B >=2.5m of lower plate, the length of lower plate steel bar stress can use 0.9 times of radius, along radial direction Arrangement；

(3) when reinforcing bar demand is less than the demand of distributing bar, joint plate rope should be generally carried out according to constructional reinforcement The arrangement of reinforcement of the lower plate on basis.