Calculation method of transverse bearing characteristics of slope pile foundation

Abstract

The application discloses a kind of calculation methods of slope pile foundation transverse bearing characteristics, including obtaining the engineering geology parameter of slope foundation, pile foundation parameter and pile soil friction parameter;Stratification is carried out to soil body;Strain wedge depth, strain wedge number and strain wedge strain are set;The geometric parameters and mechanical parameters of strain wedge are calculated;The horizontal displacement value of pile body is calculated;The first zero point depth of strain and horizontal displacement value of strain wedge is calculated;The depth value and strain value of soil body strain wedge before pile are obtained by judging and iterative calculation to strain and first zero point depth value of strain wedge;The calculation of pile foundation transverse bearing characteristics is completed by the depth value and strain value of soil body strain wedge before pile.The application is designed by innovative algorithm steps and calculation, not only realizes the iterative calculation of slope foundation strain wedge, realizes the fast and accurate calculation of strain wedge depth and strain, but also the application has high reliability, good accuracy and high efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of civil engineering, and particularly relates to a calculation method for lateral bearing characteristics of a slope pile foundation. BACKGROUND

[0002] With the development of economy and technology and the improvement of people's living standards, the infrastructure construction in China is also developing rapidly. Pile foundations are applied in the fields of railways, highways and wind power generation. In the specific use process, the pile foundation will be affected by horizontal loads such as wind load, vehicle load and earthquake action; therefore, it is of great significance to analyze the lateral bearing characteristics of the pile foundation in actual engineering.

[0003] The address conditions of the engineering construction site are extremely complex, and the pile foundation will inevitably be built in the vicinity of the slope area or on the slope surface. Under this condition, the pile foundation may face certain risks: the slope effect will cause the pile foundation to have a significant decrease in bearing capacity and a significant increase in horizontal displacement. Therefore, it is of great engineering significance to study the lateral bearing characteristics of the horizontally loaded pile on the slope foundation.

[0004] At present, the research methods for the lateral bearing characteristics of the horizontally loaded pile mainly include the elastic foundation beam method (BEF), the p-y curve method and the strain wedge method. However, the research methods for the horizontally loaded pile on the slope foundation mainly focus on the weakening of the limit soil resistance and the weakening of the horizontal foundation modulus, and there is no research on the influence of the slope effect on the bearing mechanism of the pile foundation. SUMMARY

[0005] The purpose of the present application is to provide a calculation method for the lateral bearing characteristics of the slope pile foundation, which has high reliability, good accuracy and high efficiency.

[0006] The calculation method for the lateral bearing characteristics of the slope pile foundation provided by the present application comprises the following steps:

[0007] S1. Obtain the engineering geological parameters of the slope foundation, the pile foundation parameters and the pile-soil friction parameters;

[0008] S2. Layer the soil according to the buried depth of the pile foundation;

[0009] S3. Set the strain wedge depth, the strain wedge number and the strain wedge strain;

[0010] S4. Calculate the geometric parameters and the mechanical parameters of the strain wedge through the strain wedge theory, the obtained parameter values and the set parameter values;

[0011] S5. Calculate the horizontal displacement value of the pile body according to the mechanical parameters of the strain wedge obtained in step S4;

[0012] S6. Calculate the strain of the strain wedge and the first zero point depth of the horizontal displacement value of the pile body obtained in step S5;

[0013] S7. Judge and iteratively calculate the strain of the strain wedge and the first zero point depth value obtained in step S6, so as to obtain the depth value and strain value of the strain wedge of the soil in front of the pile;

[0014] S8. Complete the calculation of the lateral bearing characteristics of the pile foundation by the depth value and strain value of the strain wedge of the soil in front of the pile obtained in step S7.

[0015] The engineering geology parameters, pile foundation parameters and pile-soil friction parameters of the slope foundation obtained in step S1 specifically include the following steps:

[0016] The obtained parameters include:

[0017] Engineering geology parameters: soil bulk density γ, cohesion c, internal friction angle 50% soil failure stress corresponding soil strain ε 50 , 80% soil failure stress corresponding soil strain ε 80 , slope angle θ;

[0018] Pile foundation parameters: pile foundation depth L, pile diameter D, load loading height e, pile foundation bending stiffness EI and pile foundation shape parameters (S1, S2);

[0019] Pile-soil friction parameters: pile-soil friction parameters

[0020] The stratification of the soil according to the depth of the pile foundation in step S2 specifically includes the following steps:

[0021] The depth of a single soil layer is set as Δh, the upper depth of the soil layer is z si , and the central point depth of the soil layer is z ci .

[0022] The setting of the strain wedge depth, the number of strain wedges and the strain of the strain wedge in step S3 specifically includes the following steps:

[0023] In the initial setting, the strain wedge depth is set as L sw , the number of strain wedges is N, and the strain of the jth strain wedge is ε j .

[0024] The calculation of the geometric parameters and mechanical parameters of the strain wedge by the strain wedge theory, the obtained parameter values and the set parameter values in step S4 specifically includes the following steps:

[0025] The stress level SL j of the jth strain wedge is calculated by the following formula:

[0026]

[0027] where ε 50 is the soil strain corresponding to 50% of the soil failure stress; ε j is the strain of the jth strain wedge; ε 80 is the soil strain corresponding to 80% of the soil failure stress;

[0028] Calculate the spread angle of the jth strain wedge is where is the internal friction angle;

[0029] Calculate the height h of the jth strain wedge j is where θ is the slope angle, β mj is the base angle of the jth strain wedge;

[0030] Calculate the depth L of the upper soil wedge s is where L sw is the strain wedge calculation depth;

[0031] Calculate the interface length L of the jth strain wedge j is L j = (h j - h j-1 ) tan β mj ;

[0032] Calculate the frontmost calculation width L(i) of each layer of soil

[0033]

[0034] Calculate the strain wedge stress Δσ hi is where SL is the stress level coefficient, σ vi is the vertical effective stress and γ is the soil unit weight, z si is the depth of the soil layer, and c is the cohesion;

[0035] Calculate the pile side shear stress τ i is where is the soil friction angle, is the pile-soil interface friction angle;

[0036] Calculate the soil resistance distribution p of each layer of the strain wedge sw is p sw = S1 Δσ hi L(i) + 2 S2 τ i D, where L(i) is the frontmost calculation width of each layer of soil;

[0037] The upper soil wedge adopts friction force to calculate the soil resistance distribution, and the friction coefficient is set as α SL ;

[0038] The shear force difference V between the upper soil body and the lower soil body is calculated by the following formula sd :

[0039]

[0040] In the formula, μ is the friction factor; Δh is the depth of a single soil layer; θ is the slope angle; is the diffusion angle of the first strain wedge;

[0041] The shear force V on both sides of the wedge is calculated l : In the formula, K0 is the lateral earth pressure coefficient;

[0042] The pile side shear force V is calculated p : p = 2S2τ i DΔh;

[0043] The value of α is calculated by the condition that the soil resistance of the lowermost layer of the upper soil wedge is equal to the soil resistance of the uppermost layer of the lower strain wedge SL .

[0044] The soil resistance distribution p of the upper soil wedge is calculated s :

[0045] Finally, the soil resistance distribution of the pile foundation is [p s , p sw ].

[0046] The horizontal displacement value of the pile body is calculated according to the mechanical parameters of the strain wedge obtained in step S4, and the specific steps are as follows:

[0047] The horizontal displacement of the pile foundation is calculated by the finite rod element method, and the horizontal displacement y j of the jth strain wedge is obtained.

[0048] The first zero point depth of the strain and horizontal displacement value of the strain wedge is calculated according to the horizontal displacement value of the pile body obtained in step S5, and the specific steps are as follows:

[0049] The strain ε aj of the strain wedge is calculated L j is the length of the jth strain wedge;

[0050] The first zero point depth value L0 of the horizontal displacement of the pile body is extracted.

[0051] The step S7 judges and iteratively calculates the strain and the depth value of the first zero point of the strain wedge obtained in the step S6, so as to obtain the depth value and the strain value of the strain wedge in front of the pile, and specifically comprises the following steps:

[0052] A. judging the strain ε aj of the strain wedge obtained in the step S6 and the strain ε j of the jth strain wedge set:

[0053] If ε aj - ε j ≥ s, the strain of the jth strain wedge is updated to ε , and the next round of calculation is performed by returning to the step S4;

[0054] If ε aj - ε j < s, the following step is performed.

[0055] s is a threshold value set;

[0056] B. judging the first zero point depth value L0 of the horizontal displacement of the pile body obtained in the step S6 and the strain wedge depth L sw set:

[0057] If L0-L sw ≥ Δhh, the strain wedge depth is updated to L , and the next round of calculation is performed by returning to the step S3;

[0058] If L0-L sw < Δhh, the following step is performed.

[0059] The step S8 completes the calculation of the lateral bearing characteristics of the pile foundation by using the depth value and the strain value of the strain wedge in front of the pile obtained in the step S7, and specifically comprises the following steps:

[0060] The depth value and the strain value of the strain wedge in front of the pile obtained at present are obtained, the soil resistance in front of the pile is calculated, and then the calculation and analysis of the lateral bearing characteristics of the pile foundation are completed.

[0061] The calculation method of the lateral bearing characteristics of the slope pile foundation provided by the application realizes the iterative calculation of the strain wedge of the slope foundation, realizes the fast and accurate calculation of the strain wedge depth and the strain, and has high reliability, good accuracy and high efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 The figure is a method flowchart of the application.

[0063] Figure 2The figure is a schematic diagram of a three-dimensional model of a strain wedge in the method of the present application, and a single-layer strain wedge model and a multi-layer strain wedge model.

[0064] Figure 3 The figure is a schematic diagram of strain wedge soil resistance calculation in the method of the present application.

[0065] Figure 4 The figure is a schematic diagram of upper soil wedge soil resistance calculation in the method of the present application.

[0066] Figure 5 The figure is a schematic diagram of a strain iteration process in the method of the present application.

[0067] Figure 6 The figure is a schematic diagram of a strain wedge depth iteration process in the method of the present application. DETAILED DESCRIPTION

[0068] As Figure 1 shown is a method flow schematic diagram of the method of the present application: the method for calculating the lateral bearing characteristics of the slope pile foundation provided by the present application, comprising the following steps:

[0069] S1. Obtain the engineering geological parameters of the slope foundation, the pile foundation parameters and the pile-soil friction parameters; specifically comprising the following steps:

[0070] The obtained parameters include:

[0071] Engineering geological parameters: soil bulk density γ, cohesion c, internal friction angle 50% soil failure stress corresponding to soil strain ε 50 , 80% soil failure stress corresponding to soil strain ε 80 , slope angle θ;

[0072] Pile foundation parameters: pile foundation depth L, pile diameter D, load loading height e, pile foundation bending stiffness EI and pile foundation shape parameters (S1, S2);

[0073] Pile-soil friction parameters: pile-soil friction parameters

[0074] S2. Stratify the soil according to the depth of the pile foundation; specifically comprising the following steps:

[0075] The depth of a single soil layer is set as Δh, the upper depth of the soil layer is z si , and the central point depth of the soil layer is z ci .

[0076] S3. Set the strain wedge depth, the number of strain wedges and the strain of the strain wedge; specifically comprising the following steps:

[0077] In the initial setting, the strain wedge depth is set as L sw , the number of strain wedges is N, and the strain of the jth strain wedge is εj ;

[0078] S4. Using strain wedge theory, the obtained parameter values, and the set parameter values, calculate the geometric and mechanical parameters of the strain wedge; specifically including the following steps (calculation model as follows). Figure 2 As shown):

[0079] The stress level SL of the j-th strain wedge is calculated using the following formula. j :

[0080]

[0081] In the formula ε 50 ε represents the soil strain corresponding to 50% of the soil failure stress. j Let ε be the strain of the j-th strain wedge; 80 The soil strain corresponding to 80% of the soil failure stress;

[0082] Calculate the diffusion angle of the j-th strain wedge. for in It is the internal friction angle;

[0083] Calculate the height h of the j-th strain wedge. j for Where θ is the slope angle, β mj Let be the base angle of the j-th strain wedge;

[0084] Calculate the depth L of the upper soil wedge. s for Where L sw Calculate the depth of the strain wedge;

[0085] Calculate the interface length L of the j-th strain wedge. j For L j =(h j -h j-1 )tanβ mj ;

[0086] The calculated width L(i) of the foremost section of each soil layer is:

[0087]

[0088] Calculate the strain wedge stress Δσ hi for Where SL is the stress level coefficient, σ vi For vertical effective stress and γ is the soil weight, z si denoted as the upper depth of the soil layer, and c represents the cohesion.

[0089] Calculate the shear stress τ on the pile side i for wherein is the friction angle of the soil mass, is the friction angle of the pile-soil interface;

[0090] Calculate the soil resistance distribution p of each layer of the strain wedge sw is p sw = S1Δσ hi L(i) + 2S2τ i D, wherein L(i) is the calculated width of the frontmost layer of soil (as shown in Figure 3 );

[0091] The upper soil wedge uses friction to calculate the soil resistance distribution (as shown in Figure 4 ), and the friction coefficient is set to α SL ;

[0092] The shear force difference V between the upper layer of soil and the lower layer of soil is calculated using the following formula sd :

[0093]

[0094] wherein μ is the friction factor; Δh is the depth of a single soil layer; θ is the slope angle; is the spread angle of the first strain wedge;

[0095] Calculate the shear force V on both sides of the wedge l is wherein K0 is the lateral earth pressure coefficient;

[0096] Calculate the pile side shear force V p is V p = 2S2τ i DΔh;

[0097] The value of α SL is calculated by the condition that the soil resistance of the lowermost layer of the upper soil wedge is equal to the soil resistance of the uppermost layer of the lower strain wedge;

[0098] The soil resistance distribution p of the upper soil wedge is calculated s is

[0099] Finally, the soil resistance distribution of the pile foundation is obtained as [p s , p sw ];

[0100] S5. Calculate the horizontal displacement value of the pile body according to the mechanical parameters of the strain wedge obtained in step S4; specifically including the following steps:

[0101] Calculate the horizontal displacement of the pile foundation by the finite rod element method, and obtain the horizontal displacement y j of the jth strain wedge at the interface;

[0102] S6. Calculate the first zero point depth of the strain wedge according to the horizontal displacement value of the pile body obtained in step S5; specifically including the following steps:

[0103] Calculate the strain of the strain wedge L j is the interface length of the jth strain wedge;

[0104] Extract the first zero point depth value L0 of the horizontal displacement of the pile body;

[0105] S7. Judge and iteratively calculate the strain of the strain wedge and the first zero point depth value obtained in step S6, so as to obtain the depth value and strain value of the strain wedge in front of the pile; specifically including the following steps:

[0106] A. Judge the strain ε aj of the strain wedge obtained in step S6 and the set strain ε j of the jth strain wedge:

[0107] If ε aj - ε j ≥ s, update the strain of the jth strain wedge to ε , and return to step S4 for the next round of calculation (as shown in Figure 5 );

[0108] If ε aj - ε j < s, proceed to the subsequent steps;

[0109] s is a set threshold value;

[0110] B. Judge the first zero point depth value L0 of the horizontal displacement of the pile body obtained in step S6 and the set strain wedge depth L sw :

[0111] If L0-L sw ≥ Δhh, update the strain wedge depth to L , and return to step S3 for the next round of calculation;

[0112] If L0-L sw < Δhh, proceed to the subsequent steps (as shown in Figure 6 );

[0113] S8. Complete the calculation of the lateral bearing characteristics of the pile foundation through the depth value and strain value of the strain wedge in front of the pile obtained in step S7; specifically including the following steps:

[0114] Obtain the depth value and strain value of the strain wedge in front of the pile, calculate the soil resistance in front of the pile, and then complete the calculation and analysis of the lateral bearing characteristics of the pile foundation.

Claims

1. A method for calculating the lateral bearing characteristics of a batter pile foundation, comprising the following steps: S1. Obtaining the engineering geological parameters of the batter foundation, the pile foundation parameters and the pile-soil friction parameters; S2. Layering the soil according to the buried depth of the pile foundation; S3. Setting the strain wedge depth, the number of strain wedges and the strain of the strain wedges; S4. Calculating the geometric parameters and mechanical parameters of the strain wedges by the strain wedge theory, the obtained parameter values and the set parameter values; specifically comprising the following steps: The stress level of the jth strain wedge is calculated using the following equation : In the formula is the soil strain corresponding to 50% soil failure stress; is the strain of the jth strain wedge; is the soil strain corresponding to 80% soil failure stress; Calculate the diffusion angle of the jth strain wedge For where is the internal friction angle; Calculate the height of the jth strain wedge For where is the slope angle, is the base angle of the jth strain wedge; Calculating the depth of the upper soil wedge For where is the depth of the strain wedge; calculating the interface length of the jth strain wedge to ; calculating the frontmost calculation width of each layer of soil to ; Computing strain wedge stresses For where is the stress level coefficient, is an intermediate variable and , is the unit weight of the soil, is the depth of the upper soil layer, is the cohesion force; Computing the pile side shear stress For where is the soil friction angle, is the pile-soil interface friction angle; calculating the resistance distribution of each layer of soil of the strain wedge for wherein is the calculated width of the frontmost section of each layer of soil; is the pile diameter; is the pile foundation shape parameter; The upper soil wedge adopts friction force to calculate the soil resistance distribution, and the friction coefficient is set as ; The difference in shear between the upper and lower soil bodies is calculated using the following equation : In the formula is the friction factor; is the single soil layer depth; is the slope angle; is the first strain wedge spread angle; Compute the shear force on both sides of the wedge For where is the lateral earth pressure coefficient; is the depth of the center point of the soil layer; Computing pile side shear force To ; The value of is calculated by the condition that the resistance of the lowermost soil layer of the upper soil wedge is equal to the resistance of the uppermost soil layer of the lower strain wedge . The upper soil wedge soil resistance distribution is calculated To ; Finally , the distribution of soil resistance of pile foundation is obtained as ; S5. Calculating the horizontal displacement value of the pile body according to the mechanical parameters of the strain wedges obtained in step S4; S6. Calculating the first zero point depth of the strain and the horizontal displacement value of the strain wedges according to the horizontal displacement value of the pile body obtained in step S5; S7. Judging and iteratively calculating the strain and the first zero point depth value of the strain wedges obtained in step S6, thereby obtaining the depth value and the strain value of the strain wedges of the soil in front of the pile; S8. Completing the calculation of the lateral bearing characteristics of the pile foundation by the depth value and the strain value of the strain wedges of the soil in front of the pile obtained in step S7.

2. The method of calculating the lateral load carrying capacity of a slope pile foundation according to claim 1, characterized in that The obtaining of the engineering geological parameters of the batter foundation, the pile foundation parameters and the pile-soil friction parameters in step S1 specifically comprises the following steps: The obtained parameters include: Engineering geological parameters: soil bulk density , cohesion , internal friction angle , soil strain corresponding to 50% soil failure stress , soil strain corresponding to 80% soil failure stress , slope angle ; Pile foundation parameters: pile foundation depth , pile diameter , load loading height , pile foundation bending stiffness and pile foundation shape parameters ; Pile-soil friction parameters: pile-soil friction parameters .

3. A method of calculating the lateral load carrying capacity of a slope pile foundation according to claim 2, characterised in that The layering of the soil according to the buried depth of the pile foundation in step S2 specifically comprises the following steps: The depth of the single soil layer is set to , the depth of the upper part of the soil layer is , and the depth of the center point of the soil layer is .

4. The method of calculating the lateral load carrying capacity of a slope pile foundation according to claim 3, characterized in that The setting of the strain wedge depth, the number of strain wedges and the strain of the strain wedges in step S3 specifically comprises the following steps: At initial setup, the strain wedge depth is set to , the number of strain wedges is set to , and the strain of the jth strain wedge is set to .

5. The method of calculating the lateral load carrying capacity of a slope pile foundation according to claim 4, characterized in that The calculation of the horizontal displacement value of the pile body according to the mechanical parameters of the strain wedges obtained in step S4 in step S5 specifically comprises the following steps: The horizontal displacement of the pile foundation is calculated by the finite rod element method, and the horizontal displacement of the interface of the jth strain wedge is obtained .

6. The method of calculating the lateral load carrying capacity of a slope pile foundation according to claim 5, characterized in that The calculation of the first zero point depth of the strain and the horizontal displacement value of the strain wedges according to the horizontal displacement value of the pile body obtained in step S5 in step S6 specifically comprises the following steps: calculating the strain of the strain wedge for , is the length of the interface of the jth strain wedge; The first zero point depth value of the pile body horizontal displacement is extracted .

7. A method of calculating the lateral load carrying capacity of a slope pile foundation according to claim 6, characterised in that The judging and iteratively calculating of the strain and the first zero point depth value of the strain wedges obtained in step S6 in step S7, thereby obtaining the depth value and the strain value of the strain wedges of the soil in front of the pile, specifically comprising the following steps: A. Strain of the strain wedge obtained in step S6 and the strain of the jth strain wedge set Judgment is made: If then the strain of the jth strain wedge is updated as and the process returns to step S4 for the next round of computation. If then proceed to the next step; is a set threshold value; B. The first zero point depth value of the pile body horizontal displacement obtained in step S6 and the set strain wedge depth Judgment is made: If then the strain wedge depth is updated as and the process returns to step S3 for the next iteration. If then the subsequent step is performed.

8. A method of calculating the lateral load carrying capacity of a slope pile foundation according to claim 7, characterised in that The completion of the calculation of the lateral bearing characteristics of the pile foundation by the depth value and the strain value of the strain wedges of the soil in front of the pile obtained in step S7 in step S8, specifically comprising the following steps: Obtaining the current obtained depth value and strain value of the strain wedges of the soil in front of the pile, calculating the soil resistance in front of the pile, and then completing the calculation and analysis of the lateral bearing characteristics of the pile foundation.

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