Foundation pit high-performance mobilization strength design method and system

Abstract

The invention discloses a foundation pit high-performance mobilization strength design method and system. The method comprises the steps that S1, wall deformation is decomposed into deformation mechanism superposition of different shapes; s2, calculating soil body strains corresponding to different shape deformation mechanisms; s3, superposing the soil body strain corresponding to different shape deformation mechanisms, and determining the total shear strain of the soil body; s4, calculating soil mass mobilization shear stress according to an assumed soil pressure mobilization mechanism; s5, calculating horizontal soil pressure according to the soil mass mobilization shear stress; and S6, numerical integration is conducted on the horizontal soil pressure twice, bending moment caused by the supporting load is added, and the structural bending moment applied to the wall is obtained. The technical problem that in the prior art, errors are caused to foundation pit deformation design due to the fact that soil mobilization strength is ignored is solved, and the technical effects that the soil mobilization strength is considered, and wall deformation and stress can be rapidly calculated only through a simple constitutive model are achieved.

Description

Technical Field

[0001] The invention relates to the field of foundation pit engineering, and in particular to a foundation pit high-performance mobilization strength design method and system. Background Art

[0002] The deformation of the foundation pit can directly reflect the safety status of the foundation pit and the surrounding environment. Accurately predicting the deformation during the excavation of the foundation pit is crucial to ensuring construction safety. However, due to the many uncertainties in factors such as the geological conditions, construction conditions, and support conditions of the foundation pit, accurately and quickly predicting the deformation of the foundation pit has always been a challenge.

[0003] Traditional foundation pit support design is often based on the limit equilibrium theory, assuming that the soil on the active and passive sides of the wall is destroyed, resulting in plastic collapse of the wall. It can only analyze the limit state of the foundation pit, but not the normal working state of the foundation pit. At the same time, the industry also uses numerical simulation methods such as finite element and discrete element to analyze the deformation of the foundation pit, but these methods have some limitations. For example, when performing engineering-scale design calculations, it takes a long time and consumes a lot of computing resources. At the same time, it is necessary to provide more complex soil parameters, which is a lot of work for the preliminary design of the foundation pit, and the constitutive model may not truly reflect the mechanical properties of the soil. Therefore, there is an urgent need for a method that can quickly calculate the deformation and mechanical characteristics of the soil and support structure during the foundation pit excavation process to assist in the rapid completion of the foundation pit design. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings existing in the prior art, and to propose a high-performance mobilization strength design method and system for foundation pits, which effectively solves the technical problem in the prior art that ignoring the soil mobilization strength causes errors in the foundation pit deformation design, and achieves the technical effect of considering the soil mobilization strength and quickly calculating the wall deformation and stress using only a simple constitutive model.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present application provides a high-performance mobilization strength design method for a foundation pit, the method comprising:

[0007] Step S1, according to the displacement of the wall structure, decomposing the wall deformation into superposition of deformation mechanisms of different shapes;

[0008] Step S2, calculating the soil strain corresponding to the deformation mechanisms of different shapes;

[0009] Step S3, superimposing the soil strains corresponding to the deformation mechanisms of different shapes to determine the total shear strain of the soil;

[0010] Step S4, calculating the soil mobilized shear stress according to the assumed soil pressure mobilization mechanism;

[0011] Step S5, calculating the horizontal earth pressure according to the mobilized shear stress of the soil;

[0012] Step S6, numerically integrating the horizontal earth pressure twice, adding the bending moment caused by the support load, and obtaining the structural bending moment applied to the wall;

[0013] Step S7, numerically differentiate the wall deflection obtained by the wall structure displacement twice, and multiply it by the wall bending stiffness to obtain the structural bending moment required to maintain the wall shape;

[0014] Step S8, subtracting the structural bending moment applied to the wall from the structural bending moment required to maintain the shape of the wall to obtain a bending moment error term;

[0015] Step S9, setting an error term threshold. If the bending moment error term is greater than the set error term threshold, a small displacement value is added to each degree of freedom of the wall, and the wall structure bending moment is re-iterated; otherwise, the correct wall structure displacement under the action of soil pressure and support load is obtained.

[0016] Preferably, the wall deformation in the step S1 is decomposed into deformation mechanisms of different shapes, including: a wall rotation mechanism, a wall translation mechanism and a wall articulation mechanism; wherein the wall articulation mechanism is created by superimposing two wall rotation mechanisms in different directions, the first wall rotation mechanism is to rotate around the bottom of the wall into the pit, the second wall rotation mechanism is to keep the lower part of the wall stationary, and the wall above the hinge rotates around the hinge to the outside of the pit, and the two wall rotation mechanisms are superimposed to fix the top of the wall.

[0017] Preferably, the soil strain calculation in step S2 includes: the soil shear strain increment δγ caused by the wall rotation mechanism r =2δθ, where δθ is the increment of the rotation angle around the bottom of the wall, r represents the wall rotation; the increment of the soil shear strain caused by the wall translation mechanism δγ t =2δu / h, where δu is the displacement increment of the wall translation, h is the height of the wall, and t represents the wall translation; the rotation directions of the wall rotation mechanism in different directions are represented by , where + represents rotation into the pit, and - represents rotation out of the pit.

[0018] Preferably, the soil shear strain in step S3 is

[0019] Preferably, in step S4, the earth pressure mobilization mechanism is assumed to be:

[0020]

[0021] Among them, τ mobThe soil mobilization shear stress in step S4; u is the peak undrained shear strength; γ is the soil shear strain; γ M＝2 For when c u The strain when half of the mobilization is completed; b is an empirical index, usually taken as 0.6; γ M＝2 The value of is measured using triaxial soil tests, or it can be calculated using the empirical formula:

[0022]

[0023] Among them, I p is the plasticity index; p0′ is the initial average effective stress; p atm It is the standard atmospheric pressure, which is 101.3 kPa.

[0024] Preferably, the horizontal earth pressure in step S5 is σ h =σ v ±2τ mob , where σ v is the vertical stress, ± indicates the direction of wall movement relative to the soil and is used to determine active or passive loads.

[0025] Preferably, the support load in step S6 is calculated by the axial shortening of the pillar caused by the displacement of the wall, and the support load only works in compression but not in tension. The structural bending moment applied to the wall in step S6 is: M1 = ∫∫σ h dy+∑F prop h, where F prop is the support load.

[0026] Preferably, the structural bending moment required to maintain the wall shape in step S7 is: Where EI is the wall stiffness and v is the wall deflection.

[0027] Preferably, the iterative wall structure displacement in step S9 is based on the tangent stiffness matrix, which is assembled by adding a small displacement value to each degree of freedom of the wall and monitoring the change of the bending moment error at each node of the wall.

[0028] In a second aspect, the present application provides a high-performance mobilization strength design system for a foundation pit, the system comprising:

[0029] A wall deformation decomposition module, which is used to decompose the wall deformation into superpositions of deformation mechanisms of different shapes according to the displacement of the wall structure;

[0030] A soil strain calculation module, the soil strain calculation module is used to calculate the soil strain corresponding to the deformation mechanisms of different shapes;

[0031] A soil shear strain calculation module, the soil shear strain calculation module is used to superimpose the soil strains corresponding to the deformation mechanisms of different shapes to determine the total soil shear strain;

[0032] A soil mobilization shear stress calculation module, wherein the soil mobilization shear stress module is used to calculate the soil mobilization shear stress according to an assumed soil pressure mobilization mechanism;

[0033] A horizontal earth pressure calculation module, the horizontal earth pressure module is used to calculate the horizontal earth pressure according to the soil mobilization shear stress;

[0034] A structural bending moment calculation module applied to the wall, the structural bending moment calculation module applied to the wall is used to perform two numerical integrations on the horizontal earth pressure, add the bending moment caused by the support load, and obtain the structural bending moment applied to the wall;

[0035] A structural bending moment calculation module required to maintain the wall shape, the structural bending moment calculation module required to maintain the wall shape is used to perform two numerical differentiations on the wall deflection obtained by the wall structure displacement, and multiply it by the wall bending stiffness to obtain the structural bending moment required to maintain the wall shape;

[0036] A bending moment error term calculation module, the bending moment error term calculation module is used to obtain a bending moment error term by subtracting the structural bending moment applied to the wall from the structural bending moment required to maintain the wall shape;

[0037] An error term threshold setting module, wherein the error term threshold setting module is used to assume an error term threshold;

[0038] The wall structure displacement calculation module is used to determine: if the bending moment error term is greater than the set error term threshold, a small displacement value is added to each degree of freedom of the wall, and the wall structure bending moment is re-iterated; otherwise, the correct wall structure displacement under the action of soil pressure and support load is obtained.

[0039] The present invention has the following beneficial effects:

[0040] The present application first decomposes the wall deformation into the superposition of deformation mechanisms of different shapes according to the displacement of the wall structure, then calculates the soil strain corresponding to the deformation mechanisms of different shapes, then superimposes the soil strain corresponding to the deformation mechanisms of different shapes, determines the total shear strain of the soil, and then calculates the soil mobilization shear stress according to the assumed soil pressure mobilization mechanism, and then calculates the horizontal soil pressure according to the soil mobilization shear stress, and then numerically integrates the horizontal soil pressure twice, adds the bending moment caused by the support load, and obtains the structural bending moment applied to the wall. The wall deflection obtained by the wall structure displacement is numerically differentiated twice and multiplied by the wall bending stiffness to obtain the structural bending moment required to maintain the wall shape, and then the structural bending moment applied to the wall is subtracted from the structural bending moment required to maintain the wall shape to obtain the bending moment error term, and finally sets the error term threshold. If the bending moment error term is greater than the set error term threshold, a small displacement value is added to each degree of freedom of the wall, and the wall structure bending moment is re-iterated; otherwise, the correct wall structure displacement under the action of soil pressure and support load is obtained. The technical problem of ignoring the soil mobilization strength and causing errors in the foundation pit deformation design in the prior art is effectively solved, and the technical effect of considering the soil mobilization strength and quickly calculating the wall deformation and stress only by using a simple constitutive model is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a process flow of a foundation pit high-performance mobilization strength design method proposed by the present invention;

[0042] Figure 2 It is a schematic diagram of the superposition of deformation mechanisms of different shapes of wall deformation proposed by the present invention;

[0043] Figure 3 The observed values ​​of horizontal displacement and predicted values ​​of deflection of the wall at different construction periods proposed by the present invention;

[0044] Figure 4 The present invention provides a block diagram of a foundation pit high-performance mobilization strength design system.

[0045] In the figure: h is the horizontal stress, σ v is the vertical stress, τ mob is the mobilized shear stress of soil, F prop is the supporting load, h is the height of the wall, EI is the wall stiffness, v is the wall deflection, ∫∫σ h dy represents two numerical integrations of horizontal stress. represents the double numerical differentiation of the wall deflection. DETAILED DESCRIPTION

[0046] The present invention provides a performance-mobilisable strength design (P-MSD) method and system for a foundation pit, which is used to solve the technical problem in the prior art that errors in foundation pit deformation design are caused by ignoring soil mobilization strength.

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0048] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or modules that are not explicitly listed or inherent to these processes, methods, products or devices.

[0049] Example 1: Figure 1 As shown, the present invention provides a high-performance mobilization strength design (P-MSD) method for foundation pits, which is used to directly and quickly calculate wall deformation and stress by considering the mobilization strength of soil and using only a simple constitutive model, so as to provide effective information for decision makers to optimize foundation pit support measures. The method includes:

[0050] According to the displacement of the wall structure, the wall deformation is decomposed into the superposition of deformation mechanisms of different shapes, where the wall deformation is decomposed into deformation mechanisms of different shapes, such as Figure 2 As shown, it includes: wall rotation mechanism, wall translation mechanism and wall hinge mechanism. The wall hinge mechanism is created by superimposing two wall rotation mechanisms in different directions. The first wall rotation mechanism is to rotate around the bottom of the wall into the pit. The second wall rotation mechanism is that the lower part of the wall remains stationary, and the wall above the hinge rotates around the hinge to the outside of the pit. The superposition of the two wall rotation mechanisms fixes the top of the wall.

[0051] After decomposing the wall deformation into deformation mechanisms of different shapes and superimposing them, the soil strain corresponding to the deformation mechanisms of different shapes is calculated, among which the soil shear strain increment δγ caused by the wall rotation mechanism is r =2δθ, where δθ is the increment of the outward rotation angle around the bottom of the wall, and r represents the wall rotation; the increment of the soil shear strain caused by the wall translation mechanism δγ t=2δu / h, where δu is the displacement increment of the wall translation, h is the height of the wall, and t represents the wall translation; the rotation directions of the wall rotation mechanisms in different directions are represented by ±, where + represents rotation into the pit and - represents rotation out of the pit.

[0052] After calculating the soil strains corresponding to the deformation mechanisms of different shapes, the soil strains corresponding to the deformation mechanisms of different shapes are superimposed to determine the total shear strain of the soil, where the soil shear strain calculation formula is:

[0053] After determining the soil shear strain, the soil mobilized shear stress is calculated according to the assumed soil pressure mobilization mechanism, where the assumed soil pressure mobilization mechanism is:

[0054]

[0055] Among them, τ mob Mobilized shear stress for soil. u is the peak undrained shear strength; γ is the soil shear strain; M＝2 For when c u The strain when half of the mobilization is completed; b is an empirical index, usually taken as 0.6; γ M＝2 The value of is measured using triaxial soil tests, or it can be calculated using the empirical formula:

[0056]

[0057] Among them, I p is the plasticity index; p0 is the initial average effective stress; p atm It is the standard atmospheric pressure, which is 101.3 kPa.

[0058] After obtaining the mobilized shear stress of the soil, calculate the horizontal earth pressure: h =σ v ±2τ mob , where σ v is the vertical stress, ± indicates the direction of wall movement relative to the soil and is used to determine active or passive loads.

[0059] According to the calculated horizontal earth pressure, two numerical integrations are performed, and the bending moment caused by the support load is added to obtain the structural bending moment applied to the wall. The support load is calculated by the axial shortening of the support caused by the wall displacement. The support load only works in compression but not in tension. The structural bending moment applied to the wall is: M1 = ∫∫σ h dy+∑F prop h, where F prop To support the load.

[0060] Next, the wall deflection obtained by the wall structural displacement is numerically differentiated twice and multiplied by the wall bending stiffness to obtain the structural bending moment required to maintain the wall shape: Where EI is the wall stiffness and v is the wall deflection.

[0061] The moment error term is obtained by further subtracting the structural bending moment applied to the wall from the structural bending moment required to maintain the shape of the wall.

[0062] Finally, the error term threshold is set. If the bending moment error term is greater than the set error term threshold, a small displacement value is added to each degree of freedom of the wall, and the wall structure bending moment is re-iterated; otherwise, the correct wall structure displacement under the action of soil pressure and support load is obtained.

[0063] In a preferred implementation manner provided by an embodiment of the present invention, iterating the wall structure displacement includes:

[0064] Based on the tangent stiffness matrix, it is assembled by adding a small displacement to each degree of freedom of the wall and monitoring the change in the bending moment error at each node of the wall.

[0065] In order to better understand the method in the present application, the prediction of the horizontal displacement of the wall measured by one of the inclinometers of a deep foundation pit of a subway station is taken as an example in this embodiment. The basic information of the foundation pit and the support load information are shown in Table 1 and Table 2 respectively; the wall deflection is measured at a depth interval of 0.5m at the inclinometer point, and the measured data are shown in Table 3; the prediction results of the foundation pit deformation according to the foundation pit high performance mobilization strength design (P-MSD) method determined by the method in the present invention are shown in Table 3. Figure 3 , where the prediction value on the 3rd day is obtained by using the information that the excavation depth is 1m in Table 1 and Table 2; the prediction value on the 14th day is obtained by using the information that the excavation depth is 2.7m in Table 1 and Table 2; the prediction value on the 27th day is obtained by using the information that the excavation depth is 3.1m in Table 1 and Table 2; the prediction value on the 46th day is obtained by using the information that the excavation depth is 6.2m in Table 1 and Table 2; the prediction value on the 56th day is obtained by using the information that the excavation depth is 7.2m in Table 1 and Table 2; the prediction value on the 74th day is obtained by using the information that the excavation depth is 9.2m in Table 1 and Table 2.

[0066] Table 1 Basic information of foundation pit

[0067]

[0068] Table 2 Support load information

[0069] Excavation depth: m 1 2.7 3.1 6.2 7.2 9.2 Support depth: m / 0.8 2.1 3.9 5.8 7.8 <![CDATA[Support axial stiffness: MN / m 2 > / 256 130 130 256 256

[0070] Table 3 Monitoring data of inclination measurement points

[0071]

[0072]

[0073] It can be seen that with the increase of excavation depth and the installation of support, the deformation of the retaining wall gradually changes, and the location where the maximum lateral displacement occurs gradually moves deeper. The error of the maximum lateral displacement on the 14th and 27th days is 40%, but the error on the 46th and 56th days is only 20%. During this period, the depth of the maximum lateral displacement is well predicted, and the size and deformation shape of the wall deflection are also well predicted, indicating that the prediction results of this method have good reliability.

[0074] Example 2: Based on the same inventive concept as the high performance mobilization strength design (P-MSD) method for a foundation pit in the previous example, Figure 4 As shown, the present application provides a high-performance mobilization strength design (P-MSD) system for foundation pits, and the system and method embodiments in the present application are based on the same inventive concept. The system includes:

[0075] Wall deformation decomposition module, the wall deformation decomposition module is used to decompose the wall deformation into deformation mechanism superpositions of different shapes according to the displacement of the wall structure;

[0076] Soil strain calculation module, which is used to calculate soil strain corresponding to deformation mechanisms of different shapes;

[0077] Soil shear strain calculation module, which is used to superimpose soil strains corresponding to deformation mechanisms of different shapes and determine the total soil shear strain;

[0078] Soil mobilization shear stress calculation module, the soil mobilization shear stress module is used to calculate the soil mobilization shear stress based on the assumed soil pressure mobilization mechanism;

[0079] Horizontal earth pressure calculation module, which is used to calculate horizontal earth pressure according to soil mobilization shear stress;

[0080] The structural bending moment calculation module applied to the wall is used to perform two numerical integrations on the horizontal earth pressure, add the bending moment caused by the support load, and obtain the structural bending moment applied to the wall;

[0081] A structural bending moment calculation module required to maintain the wall shape is used to perform two numerical differentiations on the wall deflection obtained by the wall structural displacement and multiply it by the wall bending stiffness to obtain the structural bending moment required to maintain the wall shape;

[0082] A bending moment error term calculation module is used to obtain a bending moment error term by subtracting the structural bending moment applied to the wall from the structural bending moment required to maintain the shape of the wall;

[0083] An error term threshold setting module, the error term threshold setting module is used to assume an error term threshold;

[0084] The wall structure displacement calculation module is used to determine: if the bending moment error term is greater than the set error term threshold, a small displacement value is added to each degree of freedom of the wall, and the wall structure bending moment is re-iterated; otherwise, the correct wall structure displacement under the action of soil pressure and support load is obtained.

[0085] Furthermore, the wall deformation decomposition module is used to perform the following method:

[0086] According to the displacement of the wall structure, the wall deformation is decomposed into three different deformation mechanisms: wall rotation mechanism, wall translation mechanism, and wall hinge mechanism.

[0087] Furthermore, the soil strain calculation module is used to perform the following method:

[0088] The soil shear strain increment δγ caused by the wall rotation mechanism r =2δθ; soil shear strain increment δγ caused by wall translation mechanism t =2δu / h;

[0089] Furthermore, the soil shear strain calculation module is used to perform the following method:

[0090] The soil shear strain calculation formula is:

[0091] Furthermore, the soil mobilization shear stress calculation module is used to perform the following method:

[0092] The calculation formula of soil mobilized shear stress is:

[0093] Furthermore, the horizontal earth pressure calculation module is used to perform the following method:

[0094] The calculation formula of horizontal earth pressure is σ h =σ v ±2τ mob ;

[0095] Furthermore, the structural bending moment calculation module applied to the wall is used to perform the following method:

[0096] The calculation formula of the structural bending moment applied to the wall is M1 = ∫∫σ h dy+∑F prop h;

[0097] Furthermore, the structural bending moment calculation module required to maintain the wall shape is used to perform the following method:

[0098] The calculation formula for the structural bending moment required to maintain the wall shape is:

[0099] It should be noted that the above-mentioned sequence of the embodiments of the present application is only for description and does not represent the advantages and disadvantages of the embodiments. And the above-mentioned specific embodiments of this specification are described. Other embodiments are within the scope of the attached claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0100] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0101] This specification and drawings are merely exemplary illustrations of the present application and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, a person skilled in the art may make various modifications and variations to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the present application and its equivalents, the present application intends to include these modifications and variations.

Claims

1. A high performance mobilization strength design method for foundation pit, characterized in that: The method comprises: Step S1, according to the displacement of the wall structure, decomposing the wall deformation into superposition of deformation mechanisms of different shapes; Step S2, calculating the soil strain corresponding to the deformation mechanisms of different shapes; Step S3, superimposing the soil strains corresponding to the deformation mechanisms of different shapes to determine the total shear strain of the soil; Step S4, calculating the soil mobilized shear stress according to the assumed soil pressure mobilization mechanism; Step S5, calculating the horizontal earth pressure according to the mobilized shear stress of the soil; Step S6, numerically integrating the horizontal earth pressure twice, adding the bending moment caused by the support load, and obtaining the structural bending moment applied to the wall; Step S7, numerically differentiate the wall deflection obtained by the wall structure displacement twice, and multiply it by the wall bending stiffness to obtain the structural bending moment required to maintain the wall shape; Step S8, subtracting the structural bending moment applied to the wall from the structural bending moment required to maintain the shape of the wall to obtain a bending moment error term; Step S9, setting an error term threshold. If the bending moment error term is greater than the set error term threshold, a small displacement value is added to each degree of freedom of the wall, and the wall structure bending moment is re-iterated; otherwise, the correct wall structure displacement under the action of soil pressure and support load is obtained.

2. A foundation pit high performance mobilization strength design method according to claim 1, characterized in that: Decomposing the wall deformation in step S1 into deformation mechanisms of different shapes, including: a wall rotation mechanism, a wall translation mechanism and a wall articulation mechanism; The wall articulation mechanism is created by superimposing two wall rotation mechanisms in different directions, wherein the first wall rotation mechanism rotates around the bottom of the wall into the pit, and the second wall rotation mechanism keeps the lower part of the wall stationary, while the wall above the hinge rotates around the hinge out of the pit, and the two wall rotation mechanisms are superimposed to fix the top of the wall.

3. A high performance mobilization strength design method for foundation pit according to claim 1, characterized in that: The soil strain calculation in step S2 includes: the soil shear strain increment δγ caused by the wall rotation mechanism r =2δθ, where δθ is the increment of the rotation angle around the bottom of the wall, r represents the wall rotation; the increment of the soil shear strain caused by the wall translation mechanism δγ t =2δu / h, where δu is the displacement increment of the wall translation, h is the height of the wall, and t represents the wall translation; the rotation directions of the wall rotation mechanism in different directions are represented by , where + represents rotation into the pit, and - represents rotation out of the pit.

4. A high performance mobilization strength design method for foundation pit according to claim 1, characterized in that: The soil shear strain in step S3 is:

5. The high performance mobilization strength design method for foundation pit according to claim 1, characterized in that: In step S4, the earth pressure mobilization mechanism is assumed to be: Among them, τ mob The soil mobilization shear stress in step S4; u is the peak undrained shear strength; γ is the soil shear strain; γ M＝2 For when c u The strain when half of the mobilization is completed; b is an empirical index, usually taken as 0.6; γ M＝2 The value of is measured using triaxial soil tests, or it can be calculated using the empirical formula: Among them, I p is the plasticity index; p0′ is the initial average effective stress; p atm It is the standard atmospheric pressure, which is 101.3 kPa.

6. A high performance mobilization strength design method for foundation pit according to claim 1, characterized in that: The horizontal earth pressure in step S5 is σ h =σ v ±2τ mob , where σ v is the vertical stress, ± indicates the direction of wall movement relative to the soil and is used to determine active or passive loads.

7. A high performance mobilization strength design method for foundation pit according to claim 1, characterized in that: The support load in step S6 is calculated by the axial shortening of the pillar caused by the displacement of the wall. The support load only works in compression and not in tension. The structural bending moment applied to the wall in step S6 is: M1 = ∫∫σ h dy+ΣF prop h, where F prop is the support load.

8. A high performance mobilization strength design method for foundation pit according to claim 1, characterized in that: The structural bending moment required to maintain the wall shape in step S7 is: Where EI is the wall stiffness and v is the wall deflection.

9. The high performance mobilization strength design method for foundation pit according to claim 1, characterized in that: The iterative wall structure displacement in step S9 is based on the tangent stiffness matrix, which is assembled by adding a small displacement value to each degree of freedom of the wall and monitoring the change of the bending moment error at each node of the wall.

10. A high-performance mobilization strength design system for foundation pits, characterized in that: The system comprises: A wall deformation decomposition module, which is used to decompose the wall deformation into superpositions of deformation mechanisms of different shapes according to the displacement of the wall structure; A soil strain calculation module, the soil strain calculation module is used to calculate the soil strain corresponding to the deformation mechanisms of different shapes; A soil shear strain calculation module, the soil shear strain calculation module is used to superimpose the soil strains corresponding to the deformation mechanisms of different shapes to determine the total soil shear strain; A soil mobilization shear stress calculation module, wherein the soil mobilization shear stress module is used to calculate the soil mobilization shear stress according to an assumed soil pressure mobilization mechanism; A horizontal earth pressure calculation module, the horizontal earth pressure module is used to calculate the horizontal earth pressure according to the soil mobilization shear stress; A structural bending moment calculation module applied to the wall, the structural bending moment calculation module applied to the wall is used to perform two numerical integrations on the horizontal earth pressure, add the bending moment caused by the support load, and obtain the structural bending moment applied to the wall; A structural bending moment calculation module required to maintain the wall shape, the structural bending moment calculation module required to maintain the wall shape is used to perform two numerical differentiations on the wall deflection obtained by the wall structure displacement, and multiply it by the wall bending stiffness to obtain the structural bending moment required to maintain the wall shape; A bending moment error term calculation module, the bending moment error term calculation module is used to obtain a bending moment error term by subtracting the structural bending moment applied to the wall from the structural bending moment required to maintain the wall shape; An error term threshold setting module, wherein the error term threshold setting module is used to assume an error term threshold; The wall structure displacement calculation module is used to determine: if the bending moment error term is greater than the set error term threshold, a small displacement value is added to each degree of freedom of the wall, and the wall structure bending moment is re-iterated; otherwise, the correct wall structure displacement under the action of soil pressure and support load is obtained.

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