A design method of a side slope retaining wall with a buffer pressure reduction function

Abstract

The application discloses a kind of slope retaining wall design methods with buffer decompression function, comprising the following steps: obtaining the lateral total pressure of soil body;According to the deformation amount, the lateral force received by retaining wall is obtained;The thickness of buffer decompression layer is calculated;The stability parameters of retaining wall, base bearing and section strength are calculated, and whether stability parameters, base stress and section strength meet preset requirements are judged.This method avoids the problem of insufficient thickness or material waste caused by experience value, ensures that the buffer layer plays the optimal decompression effect while considering economy.Through the closed-loop process of checking, adjusting and recalculating, it is ensured that the stability, bearing capacity and section strength of the retaining wall meet the preset requirements throughout its life cycle.Through accurate calculation and parameter optimization, this method not only avoids the waste of material and construction cost caused by conservative design, but also prevents the investment in later maintenance and reinforcement caused by insufficient parameters.

Description

Technical Field

[0001] This invention relates to the field of slope retaining wall design technology, and in particular, to a slope retaining wall design method with buffering and pressure reduction function. Background Technology

[0002] In geotechnical engineering and slope protection, retaining walls, as the core structure for resisting lateral soil pressure and maintaining slope stability, are directly related to the safety and service life of the project. Especially in areas with expansive soil, the significant water absorption and expansion and water loss shrinkage characteristics of expansive soil generate continuous and variable expansion forces, which makes the load borne by the retaining wall far exceed that of ordinary soil environments.

[0003] To address the unique engineering properties of expansive soil, some design schemes attempt to incorporate a buffer layer between the retaining wall and the soil. However, existing buffer layer designs generally lack systematic theoretical support: on the one hand, a quantitative relationship has not been established between the total lateral pressure of the soil, the deformation of the buffer layer, and the actual stress on the retaining wall, resulting in inaccurate control over the pressure reduction effect of the buffer layer and the actual stress on the retaining wall; on the other hand, the determination of the buffer layer's thickness and material parameters (such as stiffness) relies heavily on empirical values, often leading to problems such as insufficient thickness causing pressure reduction failure, excessive thickness resulting in material waste, or excessive material stiffness leading to poor pressure reduction. Furthermore, existing designs lack safety verification for retaining walls after the addition of a buffer layer, failing to dynamically adjust the buffer layer parameters according to the retaining wall's stress state, further reducing the overall reliability of the retaining wall structure. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a design method for slope retaining walls with buffering and pressure-reducing functions.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A design method for a slope retaining wall with buffering and pressure reduction function includes the following steps: S1, obtaining the soil autogenous pressure on the retaining wall. Based on the preset load that the upper end of the expansive soil needs to bear, the soil load pressure exerted on the retaining wall by the preset load through the soil is obtained. Based on the lateral expansion force of expansive soil Soil self-generated pressure and soil load pressure Obtain the total lateral pressure of the soil S2, Based on the calculation model of the retaining wall buffer, obtain the total lateral pressure of the soil. Deformation of the underlying buffer and decompression layer And based on the amount of deformation Obtain the lateral force acting on the retaining wall. wherein the buffer pressure relief layer is sandwiched between the retaining wall and the expansive soil; S3, calculating the thickness T of the buffer pressure relief layer and judging whether the calculated thickness meets the preset requirement: if yes, the value of the thickness T remains unchanged or the thickness T is increased; if not, the thickness T is increased until the preset requirement is met; S4, calculating the stability parameters, the base bearing and the cross-section strength of the retaining wall, and judging whether the stability parameters, the base stress and the cross-section strength all meet the preset requirement: if yes, the thickness and the material of the buffer pressure relief layer remain unchanged; if not, at least one of the stability parameters, the base stress and the cross-section strength does not meet the requirement, the thickness of the buffer pressure relief layer is increased or / and the material of the buffer pressure relief layer is adjusted to a material with smaller rigidity, and the step S4 is returned until the stability parameters, the base stress and the cross-section strength meet the requirement.

[0007] Further, the stability parameters of the retaining wall include a first stability parameter and a second stability parameter ; the first stability parameter is calculated by the following formula: ;

[0008] the second stability parameter is calculated by the following formula: .

[0009] is the unit weight of the retaining wall; is the vertical component of ; is the horizontal component of ; is the friction coefficient of the base of the retaining wall; is the force arm of to the toe of the wall; is the force arm of to the toe of the wall; is the force arm of the self-weight of the retaining wall to the toe of the wall; is the unit height of the retaining wall; the preset requirement of the stability parameters is: ; ; is the safety threshold of the first stability parameter; is the safety threshold of the second stability parameter.

[0010] Further, the side of the retaining wall facing the buffer pressure relief layer is perpendicular to the horizontal plane, , .

[0011] Further, the preset requirement of the base bearing capacity of the retaining wall is:

[0012] ;

[0013] in ; For the eccentricity, This refers to the width of the bottom of the retaining wall; The allowable bearing capacity of the retaining wall.

[0014] Furthermore, the cross-sectional strength of the retaining wall should meet the following requirements:

[0015] ; To check the extreme normal stress at the cross section of the retaining wall; To check the self-weight stress of the retaining wall at the cross-section; To verify the eccentricity at the cross-section; This refers to the allowable stress of the retaining wall body. ; This refers to the shear stress in the horizontal section of the wall. To verify the wall width at the cross-section; The allowable stress of the retaining wall material.

[0016] Furthermore, the soil's self-generated pressure The following formula is used for calculation: The soil load pressure The following formula is used for calculation:

[0017] .

[0018] The lateral swelling force of the expansive soil The following formula is used for calculation: The total lateral pressure of the soil for: ; This represents the vertical distance from the earth pressure calculation point to the upper surface of the expansive soil. The active earth pressure coefficient, For the unit weight of expansive soil, The load on the soil by a strip unit is the load borne by the soil. The horizontal distance from the inner edge of the strip unit to the back of the wall. The width of the strip unit load. is the recommended value for horizontal expansion force; H is the depth of atmospheric influence on expansive soil, and h is the depth of rapid atmospheric influence on expansive soil.

[0019] Furthermore, the calculation model for the retaining wall buffer is as follows: ; To ensure the material stiffness of the buffer and pressure relief layer, This represents the expansion stiffness of expansive soil.

[0020] Further, the step S2 specifically comprises: S21, obtaining the deformation amount of the buffer pressure relief layer under the total lateral pressure of the soil body according to a calculation model of the buffer of the retaining wall is: ; S22, the lateral acting force on the retaining wall is equal to the acting force on the buffer pressure relief layer, then obtaining .

[0021] Further, the specific steps of the step S3 are as follows: S31, the thickness T is obtained by calculation through the following formula: ; S32, judging whether the value of the thickness T is greater than the first preset threshold value: if yes, the value of the thickness T remains unchanged or the thickness T is adjusted to be larger; if not, the value of the thickness T is adjusted to be the first preset threshold value or greater than the first preset threshold value; is the elastic modulus of the buffer pressure relief layer; is the horizontal expansion rate of the expansive soil; is the calculation range of the horizontal expansion of the backfill expansive soil behind the wall.

[0022] Further, a drainage pad is attached to the side of the buffer pressure relief layer away from the retaining wall.

[0023] The present application has the following beneficial effects:

[0024] ​​The method in step S1 explicitly puts the lateral expansion force of the expansive soil, the self-generated pressure of the soil body and the preset load transmitted by the soil body load pressure into a unified calculation system, and finally obtains the total lateral pressure of the soil body, changes the defects of ignoring or roughly estimating the expansion force in the traditional design, ensures the completeness and accuracy of the load calculation of the retaining wall, and avoids the risk of overloading and damage of the retaining wall structure caused by insufficient load evaluation from the source. And the method establishes the quantitative correlation between the buffer pressure relief layer and the stress of the retaining wall, and realizes the precise controllability of the pressure relief effect. Step S2 establishes a clear corresponding relationship between the total lateral pressure of the soil body, the deformation D of the buffer pressure relief layer and the actual lateral force of the retaining wall through the retaining wall buffer calculation model, breaking through the bottleneck of the lack of theoretical model calculation support in the existing buffer layer design; at the same time, step S3 constructs the calculation, verification and adjustment design logic for the thickness T of the buffer pressure relief layer, avoiding the problems of insufficient thickness or material waste caused by experience value, and ensuring that the buffer layer plays the optimal pressure relief effect while considering the economy. Finally, the method also introduces the material stiffness parameter adjustment and dynamic matching mechanism, which significantly improves the reliability of the retaining wall structure. Step S4 puts the material stiffness of the buffer pressure relief layer into the parameter adjustment category, and when the stability of the retaining wall, the base bearing or the cross-section strength does not meet the requirements, the buffer layer parameters can be dynamically adjusted through the combination of thickening and stiffness optimization, solving the problem of single material parameter selection and the disconnection between buffer and safety performance in the existing design; at the same time, through the closed-loop process of checking, adjusting and recalculating, it ensures that the stability, bearing capacity and cross-section strength of the retaining wall meet the preset requirements in the whole life cycle, greatly reduces the safety hazards such as cracking and displacement of the retaining wall, and prolongs the service life of the structure. Through precise calculation and parameter optimization, the method not only avoids the waste of material and construction cost caused by design conservatism, but also prevents the later repair and reinforcement investment caused by insufficient parameters, and realizes the balance between safety performance and economic cost.

[0025] In addition to the objects, features, and advantages described above, the present application has other objects, features and advantages. Hereinafter, the present application will be described in detail with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate the preferred embodiments of the application and assist in

[0027] Figure 1 is the overall flowchart of the present application;

[0028] Figure 2 is a schematic diagram of the position of the retaining wall, the buffer pressure relief layer and the expansive soil. DETAILED DESCRIPTION

[0029] It should be understood that the specific embodiments described herein are merely illustrative of the present application and should not be used to limit the present application.

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0032] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0033] Please refer to Figure 1 and Figure 2 The present invention provides a preferred embodiment of a slope retaining wall design method with buffering and pressure reduction function, comprising steps S1, S2, S3 and S4.

[0034] S1, obtain the soil self-generated pressure on the retaining wall 100. Based on the preset load that the upper end of the expansive soil 300 needs to bear, the soil load pressure exerted on the retaining wall by the preset load through the soil is obtained. Based on the lateral expansion force of expansive soil Soil self-generated pressure and soil load pressure Obtain the total lateral pressure of the soil .

[0035] S2, based on the calculation model of the 100mm buffer retaining wall, obtain the total lateral pressure of the soil. Deformation of the underlying buffer and decompression layer And based on the amount of deformation Obtain the lateral force acting on the retaining wall 100. The buffer and pressure relief layer 200 is sandwiched between the retaining wall 100 and the expansive soil 300.

[0036] S3, the thickness T of the buffer pressure relief layer 200 is calculated and it is determined whether the calculated thickness meets the preset requirement: if yes, the value of the thickness T remains unchanged or the thickness T is increased; if not, the thickness T is increased until the preset requirement is met.

[0037] S4, the stability parameters, the base bearing and the cross-section strength of the retaining wall 100 are calculated, and it is determined whether the stability parameters, the base stress and the cross-section strength all meet the preset requirement: if yes, the thickness and the material of the buffer pressure relief layer 200 remain unchanged; if not, the thickness of the buffer pressure relief layer 200 is increased or / and the material of the buffer pressure relief layer 200 is adjusted to a material with smaller rigidity, and the step S4 is returned until the stability parameters, the base stress and the cross-section strength meet the requirement.

[0038] The method in step S1 explicitly puts the lateral expansion force of the expansive soil, the self-generated pressure of the soil body and the preset load transmitted by the soil body load pressure into a unified calculation system, finally obtains the total lateral pressure of the soil body, changes the defects of ignoring or roughly estimating the expansive force in the traditional design, ensures the completeness and accuracy of the load calculation of the retaining wall, and avoids the risk of overloading damage of the retaining wall structure caused by insufficient load evaluation from the source. And the method establishes the quantitative correlation between the buffer pressure relief layer and the stress of the retaining wall, realizes the precise controllability of the pressure relief effect. Step S2 establishes the explicit corresponding relationship between the total lateral pressure of the soil body, the deformation D of the buffer pressure relief layer and the actual lateral force of the retaining wall through the retaining wall buffer calculation model, breaks through the bottleneck that the existing buffer layer design lacks theoretical model calculation support; at the same time, step S3 constructs the design logic of calculation, verification and adjustment for the thickness T of the buffer pressure relief layer, avoids the problems of insufficient thickness or material waste caused by experience value, and ensures that the buffer layer plays the optimal pressure relief effect while considering the economy. Finally, the method also introduces the material stiffness parameter adjustment and dynamic matching mechanism, which significantly improves the reliability of the retaining wall structure. Step S4 puts the material stiffness of the buffer pressure relief layer into the parameter adjustment category, when the stability of the retaining wall, the base bearing or the cross-section strength do not meet the requirements, the buffer layer parameters can be dynamically adjusted through the combination of thickening and stiffness optimization, solving the problem that the material parameter selection is single and the buffer and safety performance are disconnected in the existing design; at the same time, through the closed-loop process of checking, adjusting and recalculating, it ensures that the stability, bearing capacity and cross-section strength of the retaining wall meet the preset requirements in the whole life cycle, greatly reduces the safety hidden dangers such as cracking and displacement of the retaining wall, and prolongs the service life of the structure. Through precise calculation and parameter optimization, the method not only avoids the waste of material and construction cost caused by design conservatism, but also prevents the later repair and reinforcement investment caused by insufficient parameters, and realizes the balance between safety performance and economic cost. Through the systematic design process of pressure precise quantization, buffer parameter matching and safety performance closed-loop verification, the method effectively solves the core problems in the traditional design of the retaining wall in the expansive soil area, such as one-sided pressure calculation, blind buffer layer parameter design, and the disconnection between safety checking and buffer design, realizes the coordinated optimization of the stress control and safety performance of the retaining wall structure, and the technical effect is remarkable.

[0039] In some embodiments of the present application, the stability parameters of the retaining wall include a first stability parameter and a second stability parameter ; the first stability parameter is obtained by calculation through the following formula:

[0040] ;

[0041] The second stability parameter is obtained by calculation through the following formula:

[0042] ;

[0043] This is the unit weight of the retaining wall, expressed in kN / m³. 3 ; for The vertical component of the force; for Horizontal component of force; The friction coefficient of the retaining wall foundation can be determined through testing; for The lever arm about the toe of the wall, in meters (m). for The lever arm of the wall toe; The lever arm of the retaining wall about its own weight at the toe of the wall; The unit height of the retaining wall is 1m. The toe is the intersection of the side of the retaining wall 100 facing away from the buffer and pressure-reducing layer 200 and the ground 400.

[0044] The preset requirements for the stability parameters are as follows: ; ; The safety threshold for the first stable parameter; The safety threshold for the second stability parameter can be set according to the safety level requirements, such as... Set to 1.3. Set to 1.5.

[0045] A precise formula for the first stability parameter (anti-slip stability coefficient) and the second stability parameter (anti-overturning stability coefficient) enables a quantitative assessment of retaining wall stability. The formula incorporates key parameters such as the retaining wall's self-weight, the vertical and horizontal components of earth pressure, and the stress arm, ensuring that stability calculations comprehensively cover the core stress factors of the retaining wall. This makes the assessment results more closely reflect actual engineering scenarios and provides a reliable basis for verifying the retaining wall's safety performance. A clear safety threshold is set, providing a clear standard for stability judgment, avoiding safety redundancy or inadequacy caused by empirical judgment, and ensuring that the retaining wall's anti-slip and anti-overturning capabilities meet the project's preset requirements.

[0046] In some embodiments of the present invention, the side of the retaining wall facing the buffer and pressure-reducing layer is perpendicular to the horizontal plane; that is, the side of the retaining wall used to block the soil is perpendicular to the horizontal plane, while the other side may be a slope to achieve diagonal bracing and increase strength. When perpendicular, , Considering the structural characteristics of vertical retaining walls, the calculation of earth pressure components is simplified, redundant calculation steps are reduced, and design efficiency is improved. Furthermore, the most common setting method is to ensure that the retaining wall is perpendicular to the horizontal ground.

[0047] In some embodiments of the present invention, the base bearing capacity The preset requirements are:

[0048] ;

[0049] wherein .

[0050] is the eccentricity, is the distance between the center of gravity and the center of the retaining wall bottom; is the width of the retaining wall bottom, is the allowable bearing capacity of the retaining wall. Here is the extreme value of the calculation, taking the corresponding two values of positive and negative corresponds to the maximum value and the minimum value.

[0051] The retaining wall gravity, vertical component of earth pressure, base width and eccentricity and other parameters are taken into account in the calculation, so as to realize accurate calculation of the base stress, ensure that the base bearing capacity meets the preset requirements, and guarantee the overall stability of the retaining wall from the foundation level.

[0052] In specific embodiments of the application, the cross-sectional strength of the retaining wall should meet the following requirements:

[0053] ; .

[0054] is the extreme normal stress of the cross-section of the retaining wall, and the formula has positive and negative, which corresponds to the maximum value and the minimum value; is the wall self-weight stress of the cross-section of the retaining wall, and the unit is kPa. is the shear stress of the horizontal section of the wall; is the wall width of the cross-section, is the eccentricity of the cross-section, is the allowable stress of the wall body of the retaining wall, is the unit width, i.e. 1m, is the shear stress of the horizontal section of the wall, is the allowable stress of the wall body of the retaining wall.

[0055] The calculation standards and limit requirements are set for the normal stress and horizontal section shear stress of the cross-section of the retaining wall respectively, so as to comprehensively cover the core evaluation dimensions of the cross-sectional strength. The wall bulk density, vertical component of earth pressure, cross-sectional width and other key parameters of the cross-section are taken into account in the formula, so that the strength calculation is more targeted and accurate, and the hidden dangers such as cracking and damage of the retaining wall due to insufficient cross-sectional strength are effectively avoided, and the service life of the structure is prolonged.

[0056] In specific embodiments of the application, the self-generated pressure of the soil is calculated according to the following formula:

[0057] . The unit is kpa, The unit is kN / m 3 . The unit is m. The unit is m.

[0058] The load pressure of the soil body The calculation is obtained according to the following formula:

[0059] The calculation is to assume a strip unit placed on the soil body, The load of the strip unit on the soil body, the unit is kPa. The horizontal distance from the inner edge of the strip unit to the wall back, the unit is m. The width of the strip unit load, the unit is m.

[0060] The lateral expansion force of the expansive soil The calculation is obtained according to the following formula:

[0061] .

[0062] H is the atmospheric influence depth of the expansive soil, the unit is m. h is the atmospheric sharp influence depth of the expansive soil, the unit is m. The horizontal expansion force recommended value, the unit is kPa. The above All use the unit kPa, if you need to change to the unit of KN for calculation, can be multiplied by each formula unit area, such as multiplied by 1m 2 .

[0063] The total lateral pressure of the soil body Is:

[0064] .

[0065] The above formula realizes the accurate calculation of each partial pressure. Through the coupling calculation of multiple parameters, each partial pressure is calculated, and then superposed to obtain the total lateral pressure of the soil body, so as to ensure the integrity and scientificity of the total pressure calculation, and provide accurate load input basis for subsequent buffer pressure relief layer design and retaining wall stress analysis.

[0066] In specific embodiments of the application, the calculation model of the retaining wall buffer is: .

[0067] The material stiffness of the buffer pressure relief layer, The expansion stiffness of the expansive soil, Can be obtained by experimental test, And The unit is kPa / mm, The unit is mm. The deformation of the buffer pressure relief layer and the swelling deformation of the swelling soil are regarded as elastic deformation, the deformation of the buffer pressure relief layer is compressed deformation under the action force of the swelling soil, after the swelling of the swelling soil, the action force is released to a certain extent, so that the swelling action force is reduced, and the swelling action force reduction is , thereby obtaining a calculation model. The cooperative stress calculation model of the buffer pressure relief layer and the swelling soil is established, the quantitative relationship among the material stiffness of the buffer pressure relief layer, the swelling stiffness of the swelling soil, the deformation D and the total lateral pressure of the soil body is determined, the theoretical support is provided for the accurate calculation of the deformation D and the lateral action force of the retaining wall, the pressure relief effect of the buffer pressure relief layer can be quantified and controlled.

[0068] In the specific embodiment of the present application, step S2 specifically comprises steps S21 and S22.

[0069] S21, according to the calculation model of the retaining wall buffer, the total lateral pressure of the soil body The deformation of the buffer pressure relief layer under the total lateral pressure of the soil body is obtained as follows: S22, the lateral action force of the retaining wall is equal to the action force of the buffer pressure relief layer, then is obtained.

[0070] Based on the buffer calculation model, the specific calculation formula of the deformation D and the lateral action force of the retaining wall is derived, the direct quantitative calculation of the two key parameters is realized, the equivalent relationship between the lateral action force of the retaining wall and the action force of the buffer pressure relief layer is determined, and accurate stress data is provided for the parameter design of the buffer pressure relief layer and the safety check of the retaining wall.

[0071] Step S3 specifically comprises steps S31 and S32.

[0072] S31, the thickness T is obtained by calculation as follows: .

[0073] S32, it is judged whether the value of the thickness T is greater than the first preset threshold value:

[0074] If yes, the value of the thickness T remains unchanged or the thickness T is increased, usually the thickness of the buffer pressure relief layer has multiple specifications, it is difficult to realize full coverage of all sizes. It is judged whether the thickness T is greater than the first preset threshold value, so that the value of the thickness T is not too low to cause that there is no corresponding specification thickness of the buffer pressure relief layer to be used, usually the first preset threshold value is 30 cm. When the value of the thickness T is between the thicknesses of two specifications, the thickness T can be increased to match the thickness of the buffer pressure relief layer of one specification, which is convenient for the production and selection of the buffer pressure relief layer.

[0075] If not, the value of the thickness T is adjusted to the first preset threshold or greater than the first preset threshold, indicating that the value of the thickness T is smaller, and needs to be adjusted to match the thickness of one of the buffer pressure relief layers, facilitating the production and selection of the buffer layer. Elastic modulus of the buffer pressure relief layer, in kpa; Horizontal expansion rate of the expansive soil, in percentage; Calculation range of the horizontal expansion of the backfill expansive soil, in m, usually The height of the retaining wall is selected as twice the height of the retaining wall, in kPa, in cm. The key parameters such as elastic modulus, horizontal expansion rate, and expansion calculation range are included in the formula to avoid the thickness design blindness caused by experience value. The thickness optimization logic of calculation, judgment, and adjustment is established to ensure that the thickness meets the pressure relief requirements, avoiding both the pressure relief failure caused by insufficient thickness and the material waste caused by excessive thickness, and also ensuring that the thickness can be easily selected for use of the corresponding buffer pressure relief layer, achieving the balance between economy and practicality.

[0076] In some embodiments of the present application, a drainage mat is attached to the side of the buffer pressure relief layer away from the retaining wall. The influence of the drainage mat on the transmission of force can be ignored, so the influence of the drainage mat can be ignored in the above calculation process. The drainage mat can effectively drain the water in the soil behind the wall, further reducing the stress load of the retaining wall, prolonging the service life of the retaining wall and the buffer pressure relief layer, and improving the long-term stability of the overall structure.

[0077] The above is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for designing a side slope retaining wall having a cushion pressure reduction function, characterized by, The method comprises the following steps: S1, obtaining the soil self-generated pressure on the retaining wall S2, obtaining the preset load pressure on the retaining wall by the soil according to the preset load borne by the upper end of the expansive soil S3, obtaining the lateral total pressure on the retaining wall according to the lateral expansive force of the expansive soil the soil self-generated pressure the soil load pressure and the soil load pressure ​ S2, obtaining the deformation of the buffer pressure relief layer under the total lateral pressure of the soil according to a calculation model of the retaining wall buffer , and obtaining the lateral force on the retaining wall according to the deformation , wherein the buffer pressure relief layer is sandwiched between the retaining wall and the expansive soil​​ S3, calculating the thickness T of the buffer pressure relief layer and determining whether the calculated thickness meets the preset requirement: if yes, the value of the thickness T remains unchanged or the thickness T is increased; if no, the thickness T is increased until the preset requirement is met; S4, calculating the stability parameter, base bearing and cross-section strength of the retaining wall and determining whether the stability parameter, base stress and cross-section strength all meet the preset requirement: if yes, the thickness and material of the buffer pressure relief layer remain unchanged; if no, the thickness of the buffer pressure relief layer is increased or / and the material of the buffer pressure relief layer is adjusted to a material with smaller rigidity, and the step S4 is returned until the stability parameter, base stress and cross-section strength meet the requirement; The calculation model of the buffer of the retaining wall is: ； to buffer the material stiffness of the pressure reduction layer, to buffer the swelling stiffness of the swelling soil; The step S2 specifically comprises: S21, obtaining the deformation amount of the buffer pressure relief layer under the total lateral pressure of the soil body according to the calculation model of the retaining wall buffer is:​ ； S22, lateral force received by the retaining wall is equal to the force received by the cushioning pressure relief layer, then ; The specific steps of the step S3 are as follows: S31, the thickness T is calculated by the following formula: ; S32, determining whether the value of the thickness T is greater than a first preset threshold: if yes, the value of the thickness T remains unchanged or the thickness T is increased; if no, the value of the thickness T is adjusted to the first preset threshold or greater than the first preset threshold; to buffer the elastic modulus of the pressure reduction layer; horizontal swelling ratio of the expansive soil; The calculation range of the horizontal expansion of the backfill expansive soil behind the wall is generated.

2. The method of designing a retaining wall for a side slope with a buffering pressure reduction function according to claim 1, wherein The stability parameters of the retaining wall include a first stability parameter and a second stability parameter ; the first stability parameter is calculated by the following formula: ； said second stability parameter is calculated by the formula ； The unit weight of the retaining wall; for The vertical component of the force; for Horizontal component of force; The coefficient of friction of the retaining wall base; for The lever arm of the wall toe; for The lever arm of the wall toe; The lever arm of the retaining wall about its own weight at the toe of the wall; This refers to the unit height of the retaining wall; The preset requirement of the stability parameter is: ； ； a safety threshold for the first stability parameter; is a safety threshold for the second stability parameter.

3. The method of designing a retaining wall for a side slope with a buffering pressure reduction function according to claim 2, wherein The side of the retaining wall facing the buffer pressure reduction layer is perpendicular to the horizontal plane, .​ 4. The method of designing a retaining wall for a side slope with a buffering pressure reduction function according to claim 2, wherein Retaining wall base bearing capacity The pre-set requirements are: ； wherein ; for eccentricity, for retaining wall base width; For retaining wall allowable bearing capacity, For unit width.

5. The method of designing a retaining wall for a side slope with a buffering pressure reduction function according to claim 4, wherein The cross-section strength of the retaining wall should meet the following requirement: ； To check the maximum normal stress at the section of the retaining wall; To check the wall weight stress at the section of the retaining wall; To check the eccentricity at the section; Allowable stress for retaining wall wall; ； Shear stress for horizontal cross-section of wall To check the wall width at the section; Allowable stress for retaining wall walling materials.

6. The method of designing a retaining wall for a side slope with a buffering pressure-reducing function according to claim 1, wherein The self-generated pressure of the soil mass The self-generated pressure of the soil mass is calculated as follows: ； The soil body load pressure The obtained value is calculated according to the following formula: ； The lateral swelling force of the expansive soil The obtained value is calculated according to the following formula: ； The lateral total pressure of the soil body is: ； Hs is the vertical distance from the swelling soil surface to the calculation point for the earth pressure, K is the active earth pressure coefficient, γs is the unit weight of the swelling soil, Fs is the load of the strip unit on the soil, Ls is the horizontal distance from the inner edge of the strip unit to the wall back, Ws is the width of the strip unit load, Hs is the recommended value of the horizontal swelling force; H is the atmospheric influence depth of the swelling soil, and h is the sharp atmospheric influence depth of the swelling soil.

7. The method of designing a retaining wall for a side slope with a buffering pressure-reducing function according to claim 1, wherein The side of the buffer pressure relief layer away from the retaining wall is attached with a drainage pad.

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