Extreme support force calculation method and system for over-consolidated sandy clay tunnel face, terminal and storage medium

Abstract

The invention discloses an extreme support force calculation method and system for an over-consolidated sandy clay tunnel face, a terminal and a storage medium, and the method comprises the steps: determining model parameters, and determining equivalent strength parameters in combination with an over-consolidated sandy clay strength criterion of a coarse grain strengthening effect; according to a limit analysis theory, establishing a corrected tunnel face collapse model; the equivalent strength parameters are introduced into the collapse model, and a tunnel face collapse power equation is constructed; solving the power equation to obtain limit supporting force, and drawing a suggested design drawing of the supporting force of the tunnel face under the conditions of different over-consolidation degrees and sand contents; and determining the over-consolidation ratio and the sand content of the soil body in the tunneling process, and querying the design drawing to obtain a support force design reference value. According to the method, the ultimate soil pressure of the tunnel face under the conditions of different over-consolidation ratios and sand contents is rapidly calculated in the tunneling process, theoretical basis and design reference are provided for over-consolidated sandy clay layer tunnel engineering construction, construction safety is guaranteed, and construction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering data processing, and in particular to a method, system, terminal and computer-readable storage medium for calculating the ultimate support force of an overconsolidated sandy clay tunnel face. Background Art

[0002] Shield technology is widely used in tunnel construction because of its fast construction speed and ability to effectively control ground displacement. During tunnel shield construction, the shield machine provides support force to the tunnel face. Too little support force will cause the tunnel face to collapse, while too much support force will push the soil away from the tunnel surface, causing surface uplift and other phenomena. Therefore, a reasonable and efficient support force design method is the key to tunnel engineering construction.

[0003] Sandy clay is widely distributed in natural sedimentary layers. A large number of studies have shown that the key engineering properties of sandy clay, such as compressibility and shear strength, are significantly affected by the sand content. Natural soils usually have certain overconsolidation characteristics due to erosion of surface sediments, unloading caused by excavation of overlying soils, changes in groundwater levels, etc. Affected by the transportation and deposition processes, the degree of overconsolidation and sand content of natural soil layers often show spatial variability, resulting in real-time changes in the mechanical parameters of the soil layers with tunnel excavation. The tunnel face support force depends on the mechanical properties of the soil. However, conventional analysis methods cannot consider the influence of coarse-grained strengthening effects and overconsolidation characteristics on the mechanical behavior of the soil. Therefore, a large number of experiments are required to determine the mechanical parameters of the excavated soil layer, resulting in low calculation efficiency.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] The main purpose of the present invention is to provide a method, system, terminal and computer-readable storage medium for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, aiming to solve the problem that in the prior art, when calculating the tunnel face support force, the influence of the coarse particle strengthening effect and the overconsolidation characteristics on the mechanical behavior of the soil is not considered, and a large number of experiments are needed to determine the mechanical parameters of the excavated soil layer, resulting in low calculation efficiency.

[0006] To achieve the above object, the present invention provides a method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, the method comprising the following steps: Determine model parameters based on indoor tests, and determine equivalent strength parameters based on the model parameters and the strength criterion for overconsolidated sandy clay combined with the coarse-grained strengthening effect; According to the limit analysis theory, a modified tunnel face collapse model is established; The equivalent strength parameters of overconsolidated sandy clay were introduced into the modified tunnel face collapse model, and the tunnel face collapse power equation was constructed. Solve the tunnel face collapse power equation to obtain the ultimate support force, and draw a recommended design diagram of the tunnel face support force under different overconsolidation degrees and sand contents; Determine the overconsolidation ratio and sand content of the soil during tunnel excavation, query the recommended design drawing of the tunnel face support force, and obtain the reference value of the support force design.

[0007] Optionally, in the method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, the model parameters include: the slope of the pure clay compression curve l m , rebound curve slope k m , compression parameters N m , the critical stress ratio of pure clay M m , overconsolidation strength parameters of pure clay β m , intergranular structure parameters or , static side pressure coefficient K 0 and the pore water pressure coefficient r u ; According to the model parameters and the strength criterion of overconsolidated sandy clay combined with the coarse-grained strengthening effect, the equivalent strength parameters are determined, specifically including: Using the strength criterion for overconsolidated sandy clay: ; in, ψ a Indicates the sand content, M m represents the critical state stress ratio of pure clay, β m represents the overconsolidation strength parameter of pure clay, l m and k m They represent the slope of the compression curve and the slope of the rebound curve of pure clay, q and p' deviatoric stress and mean effective stress, respectively. represents the initial consolidation pressure, x represents the structural variables used to describe the evolution of intergranular structure, x The calculation is: ; in, e a,minrepresents the minimum porosity of sand, f a represents the sand volume fraction, or represents the inter-particle structure parameter; The equivalent strength parameter of the overconsolidated sandy clay is determined, wherein the equivalent strength parameter of the overconsolidated sandy clay adopts the Mohr-Coulomb equivalent strength parameter.

[0008] Optionally, the method for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay, wherein the determining of the equivalent strength parameter of the overconsolidated sandy clay specifically includes: Calculation of Mohr-Coulomb equivalent strength parameters of overconsolidated sandy clay using the tangent method, including the internal friction angle f' and cohesion c The slope of the tangent line to the strength criterion of sandy clay represents the tangent value of the internal friction angle tan f' , the intercept is the cohesion c ; According to different consolidation states and overconsolidation ratios of soil, the corresponding internal friction angle and cohesion are: For soil without considering the consolidation state, the Mohr-Coulomb equivalent strength parameter is: ; ; For soils with an overconsolidation ratio greater than 2, the Mohr-Coulomb equivalent strength parameter of strongly overconsolidated soil is: ; ; in, A and B All are soil parameters; ; ; For soils with an overconsolidation ratio less than 2, the strength criterion for overconsolidated sandy clay is used for weakly overconsolidated soils and normally consolidated soils. The slope and intercept of the tangent line at / 2 represent the internal friction angle f' and cohesion c .

[0009] Optionally, the method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, wherein the modified tunnel face collapse model is established based on the limit analysis theory, specifically comprising: If the collapsed body is a rigid body and undergoes rotational failure around the horizontal direction perpendicular to the tunnel axis, and the center of rotation is point O, the cross section of the collapsed body and the tunnel connection coincides; Discretize the circular section of the tunnel into several pairs of left-right symmetrical points; Generate a plane consisting of the rotation center point and the left-right symmetric points from the bottom of the tunnel section to the top of the tunnel section; Add angle steps on the plane between the rotation center point and the left and right symmetrical points of the tunnel top to generate a new plane until the end point of the collapse surface.

[0010] Optionally, the method for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay, wherein the equivalent strength parameter of the overconsolidated sandy clay is introduced into the modified tunnel face collapse model to construct the tunnel face collapse power equation, specifically includes: The determined equivalent strength parameter of overconsolidated sandy clay is introduced into the friction power in the tunnel face power equation: ; in, W F represents the friction power in the tunnel face power equation, c and f' They represent the cohesion and internal friction angle of sandy clay obtained by the tangent method, υ represents the unit velocity vector, S represents the surface area of ​​the modified tunnel face collapse model; The tunnel face collapse power equation is established based on the balance between external power and internal power, wherein the internal power includes gravity power and the external power includes friction power, support power and pore water pressure power; ; in, c sat It represents the saturated density of soil. s c represents the ultimate support force of the tunnel face, u is the pore water pressure, represents the volume strain increment of the soil skeleton, n represents the normal vector perpendicular to the failure plane, V Represents the volume of the collapsed model.

[0011] Optionally, the method for calculating the ultimate support force of the tunnel face in overconsolidated sandy clay, wherein the ultimate support force is obtained by solving the tunnel face collapse power equation, and a recommended design diagram of the tunnel face support force under different overconsolidation degrees and sand contents is drawn, specifically comprising: Solve the tunnel face collapse power equation and obtain the analytical solution of the tunnel face ultimate support force; Using MATLAB software and quadratic programming algorithm, the extreme value of the analytical solution of the ultimate support force of the tunnel face is obtained; In the MATLAB program, multiple extreme value points of the ultimate support force solution are obtained, and then the minimum value among all extreme value points is taken to obtain the global minimum value. The ultimate support force corresponding to the global minimum value is the design value. According to the model parameters, combined with the change of support force with overconsolidation ratio and sand content, the corresponding support force recommended design diagram is drawn.

[0012] Optionally, the method for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay, wherein the overconsolidation ratio and sand content of the soil during tunnel excavation are determined, and the recommended design drawing of the tunnel face support force is queried to obtain the support force design reference value, specifically including: The soil overconsolidation ratio and sand content were obtained through field tests during tunneling; Find the sand content on the recommended design drawing of tunnel face support force ψ a and intergranular structural parameters or The corresponding curve; The dimensionless pre-consolidation stress is determined according to the soil over-consolidation ratio parameter, and finally the design reference value of the support force is determined by the interpolation method.

[0013] In addition, to achieve the above-mentioned purpose, the present invention also provides a system for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, wherein the system for calculating the ultimate support force of an overconsolidated sandy clay tunnel face comprises: A parameter determination module is used to determine the model parameters based on the indoor test, and determine the equivalent strength parameters according to the model parameters and the strength criterion of overconsolidated sandy clay combined with the coarse-grained strengthening effect; Model building module, used to build a modified tunnel face collapse model based on limit analysis theory; An equation building module is used to introduce the equivalent strength parameters of overconsolidated sandy clay into the modified tunnel face collapse model and construct the tunnel face collapse power equation; A design drawing module is used to solve the tunnel face collapse power equation, obtain the ultimate support force, and draw a recommended design drawing of the tunnel face support force under different overconsolidation degrees and sand contents; The support force query module is used to determine the overconsolidation ratio and sand content of the soil during tunnel excavation, query the recommended design drawing of the tunnel face support force, and obtain the support force design reference value.

[0014] In addition, to achieve the above-mentioned purpose, the present invention also provides a terminal, wherein the terminal includes: a memory, a processor, and a program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face stored in the memory and runnable on the processor, wherein the program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, when executed by the processor, implements the steps of the method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face as described above.

[0015] In addition, to achieve the above-mentioned purpose, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, and when the program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face is executed by a processor, the steps of the method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face as described above are implemented.

[0016] In the present invention, model parameters are determined based on indoor tests, and equivalent strength parameters are determined according to the model parameters and the strength criterion of overconsolidated sandy clay combined with coarse-grained strengthening effect; a modified tunnel face collapse model is established according to the limit analysis theory; the equivalent strength parameters of overconsolidated sandy clay are introduced into the modified tunnel face collapse model, and a tunnel face collapse power equation is constructed; the tunnel face collapse power equation is solved to obtain the ultimate support force, and a recommended design diagram of the tunnel face support force under different overconsolidation degrees and sand contents is drawn; the overconsolidation ratio and sand content of the soil during tunnel excavation are determined, the recommended design diagram of the tunnel face support force is queried, and a support force design reference value is obtained. The present invention introduces the coarse-grained strengthening effect, constructs the strength criterion of over-consolidated sandy clay, and finally establishes a method for calculating the ultimate support force of the sandy clay tunnel face considering the over-consolidation degree and sand content. This method makes up for the defect that the traditional design process requires a large number of experiments to determine the mechanical parameters of the soil layer. The proposed model only needs to carry out two groups of indoor tests in advance, and the ultimate earth pressure of the tunnel face under different over-consolidation ratios and sand contents can be quickly calculated during the tunnel excavation process, which provides a theoretical basis and design reference for the construction of tunnel engineering in over-consolidated sandy clay layers, ensures construction safety, and improves construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of a preferred embodiment of a method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face of the present invention; Figure 2 It is a diagram of the collapse mechanism of the tunnel face in a preferred embodiment of the method for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay in the present invention; Figure 3It is a schematic diagram of solving the Mohr-Coulomb equivalent strength parameter by the tangent method in a preferred embodiment of the method for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay of the present invention; Figure 4 It is a schematic diagram of an example of determining a design reference value of a tunnel face support force in a preferred embodiment of a method for calculating the ultimate support force of a tunnel face in overconsolidated sandy clay according to the present invention; Figure 5 It is a structural diagram of a preferred embodiment of the ultimate support force calculation system for the tunnel face of overconsolidated sandy clay according to the present invention; Figure 6 It is a structural diagram of a preferred embodiment of the terminal of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] The method for calculating the ultimate support force of the tunnel face in overconsolidated sandy clay described in the preferred embodiment of the present invention is as follows: Figure 1 As shown, the method for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay comprises the following steps: Step S10: determining model parameters based on indoor tests, and determining equivalent strength parameters according to the model parameters and the strength criterion of overconsolidated sandy clay in combination with the coarse-grained strengthening effect.

[0020] Specifically, the model parameters include: the slope of the pure clay compression curve l m , rebound curve slope k m , compression parameters N m , the critical stress ratio of pure clay M m , overconsolidation strength parameters of pure clay β m , intergranular structure parameters or , static side pressure coefficient K 0 and the pore water pressure coefficient r u ; All model parameters can be determined through indoor tests.

[0021] Then the strength criterion of overconsolidated sandy clay was used, and its basic formula is: ; in, ψ a Indicates the sand content, Mm represents the critical state stress ratio of pure clay, β m represents the overconsolidation strength parameter of pure clay, l m and k m They represent the slope of the compression curve and the slope of the rebound curve of pure clay, q and p' deviatoric stress and mean effective stress, respectively. represents the initial consolidation pressure, x represents the structural variables used to describe the evolution of intergranular structure, x The calculation is: ; in, e a,min represents the minimum porosity of sand, f a represents the sand volume fraction, or Represents the inter-particle structure parameters.

[0022] Determine the equivalent strength parameter of overconsolidated sandy clay, the equivalent strength parameter of overconsolidated sandy clay adopts the Mohr-Coulomb equivalent strength parameter, which is calculated from the internal friction angle f' and cohesion c The specific implementation method is as follows: Figure 2 The tangent method is used to calculate the Mohr-Coulomb equivalent strength parameter of sandy clay with an overconsolidation ratio greater than 2. The slope of the tangent represents the tangent value of the internal friction angle tan f' , the intercept is the cohesion c .

[0023] According to different consolidation states and overconsolidation ratios of soil, the corresponding internal friction angle and cohesion are: (1) For soil without considering the consolidation state, the Mohr-Coulomb equivalent strength parameter is: ; ; (2) For soils with an overconsolidation ratio greater than 2, the Mohr-Coulomb equivalent strength parameter of strongly overconsolidated soil is: ; ; in, A and B All of them are soil parameters; the expressions are: ; ; (3) For soils with an overconsolidation ratio less than 2, the strength criterion for overconsolidated sandy clay is used for weakly overconsolidated soils and normally consolidated soils. The slope and intercept of the tangent line at / 2 represent the internal friction angle f' and cohesion c .

[0024] Step S20: establishing a modified tunnel face collapse model based on the limit analysis theory.

[0025] Specifically, the assumptions of the modified tunnel face collapse model are first determined as follows: (1) Assume that the collapsed body is a rigid body and undergoes rotational failure around the horizontal direction perpendicular to the tunnel axis, with the rotation center being point O; (2) The cross-section of the collapsed body and the tunnel connection coincides.

[0026] The modified face collapse model takes into account the variation of the internal friction angle with depth in the overconsolidated sandy clay layer. The modified tunnel face collapse model is generated as follows: (1) Discretize the circular cross section of the tunnel into several pairs of bilaterally symmetrical points; (2) Generate a plane consisting of the rotation center point and the left and right symmetric points from the bottom of the tunnel section to the top of the tunnel section; (3) Add an angle step on the plane between the rotation center point and the left and right symmetrical points of the tunnel top to generate a new plane until the end of the collapse surface.

[0027] like Figure 3 As shown in Figure 2, the final generated tunnel face collapse model is in the shape of a bull horn, where C Indicates the tunnel depth. D represents the tunnel diameter, h w Indicates the static head height.

[0028] Step S30: Introduce the equivalent strength parameters of overconsolidated sandy clay into the modified tunnel face collapse model to construct the tunnel face collapse power equation.

[0029] Specifically, the equivalent strength parameter of the overconsolidated sandy clay determined in step S10 is introduced into the friction power in the tunnel face power equation: ; in, W F represents the friction power in the tunnel face power equation, c and f' They represent the cohesion and internal friction angle of sandy clay obtained by the tangent method, υ represents the unit velocity vector, SRepresents the surface area of ​​the modified tunnel face collapse model.

[0030] Finally, the corresponding tunnel face collapse power equation is constructed, and its implementation method is as follows: The tunnel face collapse power equation is established based on the balance between external power and internal power. The internal power includes gravity power, and the external power includes friction power, support power, and pore water pressure power. The specific expression is: ; in, c sat It represents the saturated density of soil. s c represents the ultimate support force of the tunnel face, u is the pore water pressure, represents the volume strain increment of the soil skeleton, n represents the normal vector perpendicular to the failure plane, V Represents the volume of the collapsed model.

[0031] Step S40, solving the tunnel face collapse power equation to obtain the ultimate support force, and drawing a recommended design diagram of the tunnel face support force under different overconsolidation degrees and sand contents.

[0032] Specifically, the collapse power equation of the tunnel face is solved to obtain the analytical solution of the ultimate support force of the tunnel face; however, the analytical solution of the ultimate support force of the tunnel face contains multiple extreme values, which is difficult to solve using traditional analytical methods, so MATLAB software is used to use a quadratic programming algorithm to find the extreme values ​​of the analytical solution of the ultimate support force of the tunnel face; in the MATLAB program, multiple extreme points of the ultimate support force solution are first found, and then the minimum value of all extreme points is taken to obtain the global minimum value, and the ultimate support force corresponding to the global minimum value is the design value; according to the model parameters, combined with the change of support force with overconsolidation ratio and sand content, the corresponding support force recommended design diagram is drawn, and the horizontal axis of the support force recommended design diagram is the dimensionless prior consolidation stress / cD , the vertical axis is the dimensionless support force s c / cD ,in, c Indicates gravity (when the water level is at or above the ground surface, c is the saturation weight, when the water level is below the tunnel, c is natural heavy), D Indicates the tunnel diameter.

[0033] Step S50, determining the overconsolidation ratio and sand content of the soil during tunnel excavation, querying the recommended design drawing of the tunnel face support force, and obtaining a reference value for the support force design.

[0034] Specifically, the soil overconsolidation ratio and sand content obtained from field tests during tunnel excavation are used to find the soil overconsolidation ratio and sand content on the support force design diagram. ψ a and intergranular structural parameters or The corresponding curve determines the dimensionless pre-consolidation stress according to the soil over-consolidation ratio parameter, and finally the interpolation method is used to determine the reference value of the support force design. The following is a specific calculation case: The parameters are shown in Table 1: Table 1: Correspondence table of values ​​of various parameters

[0035] Under this condition, the different sand contents are considered in the drawing. ψ a and intergranular structural parameters or Design suggestion diagram, where or is the structural parameter of the inter-particle structure changing with the sand content. The horizontal axis of the design suggestion diagram is the dimensionless initial consolidation stress / cD , the vertical axis is the dimensionless support force s c / cD , by setting different sand contents ψ a and structural parameters or , and then use the MATLAB solution program to draw the corresponding support force design diagram, such as Figure 4 When the sand content is selected ψ a = 0.7, structural parameters or = 0.2 and dimensionless pre-consolidation stress / cD = 1.00, first find the relevant curve corresponding to the sand content and structural parameters in the support force design diagram, and then find the corresponding horizontal axis from the curve. / cD = 1.00 on the vertical axis σc / cD = 0.085, so the recommended design support force is 15.30kN.

[0036] The present invention provides a method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, which takes into account the influence of overconsolidation ratio and sand content on the ultimate support force, and provides important support for the stability analysis of the tunnel face.

[0037] The beneficial effects produced by the present invention are as follows: (1) The present invention provides a method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, which solves the problem that the traditional method cannot directly reflect the influence of sand content and overconsolidation ratio on the ultimate support force of the tunnel face. First, a collapse model of overconsolidated sandy clay is established, and the Mohr-Coulomb equivalent strength parameter is determined by combining the tangent method with the overconsolidated sandy clay strength criterion. Then, a tunnel face collapse power equation is established, and a numerical solution of the ultimate support force of the tunnel face is obtained by combining the quadratic programming algorithm.

[0038] (2) The present invention is characterized by high efficiency and practicality. The relevant soil mechanical property parameters are determined through triaxial tests, and the tunnel face support force design recommendation diagram is drawn using the MATLAB program. Combined with the soil sand content and over-consolidation ratio determined by field tests, the interpolation method is used to determine the corresponding support force design reference values ​​of soil layers under different over-consolidation degrees, which is convenient for promotion and application in actual engineering.

[0039] Furthermore, if Figure 5 As shown, based on the above-mentioned method for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay, the present invention also provides a system for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay, wherein the system for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay comprises: A parameter determination module 51 is used to determine model parameters based on indoor tests, and to determine equivalent strength parameters according to the model parameters and the strength criterion of overconsolidated sandy clay combined with the coarse-grained strengthening effect; A model building module 52 is used to build a modified tunnel face collapse model based on the limit analysis theory; An equation building module 53 is used to introduce the equivalent strength parameter of overconsolidated sandy clay into the modified tunnel face collapse model to build a tunnel face collapse power equation; A design drawing module 54 is used to solve the tunnel face collapse power equation, obtain the ultimate support force, and draw a recommended design drawing of the tunnel face support force under different overconsolidation degrees and sand contents; The support force query module 55 is used to determine the overconsolidation ratio and sand content of the soil during tunnel excavation, query the recommended design drawing of the tunnel face support force, and obtain the support force design reference value.

[0040] Furthermore, if Figure 6 As shown, based on the above-mentioned method and system for calculating the ultimate support force of the tunnel face of overconsolidated sandy clay, the present invention also provides a terminal accordingly, and the terminal includes a processor 10, a memory 20 and a display 30. Figure 6 Only some components of the terminal are shown, but it should be understood that it is not required to implement all of the components shown, and more or fewer components may be implemented instead.

[0041] In some embodiments, the memory 20 may be an internal storage unit of the terminal, such as a hard disk or memory of the terminal. In other embodiments, the memory 20 may also be an external storage device of the terminal, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the terminal. Further, the memory 20 may also include both an internal storage unit of the terminal and an external storage device. The memory 20 is used to store application software and various data installed on the terminal, such as the program code of the installation terminal. The memory 20 may also be used to temporarily store data that has been output or is to be output. In one embodiment, the memory 20 stores an ultimate support force calculation program 40 for the tunnel face of super-consolidated sandy clay, which can be executed by the processor 10, thereby realizing the ultimate support force calculation method for the tunnel face of super-consolidated sandy clay in the present application.

[0042] In some embodiments, the processor 10 may be a central processing unit (CPU), a microprocessor or other data processing chip, which is used to run the program code or process data stored in the memory 20, such as executing the ultimate support force calculation method of the over-consolidated sandy clay tunnel face.

[0043] In some embodiments, the display 30 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch device, etc. The display 30 is used to display information on the terminal and to display a visual user interface. The processor 10, the memory 20, and the display 30 of the terminal communicate with each other via a system bus.

[0044] In one embodiment, when the processor 10 executes the ultimate support force calculation program 40 for the tunnel face of overconsolidated sandy clay in the memory 20, the steps of the ultimate support force calculation method for the tunnel face of overconsolidated sandy clay as described above are implemented.

[0045] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, and when the program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face is executed by a processor, the steps of the method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face as described above are implemented.

[0046] In summary, the present invention provides a method, system, terminal and computer-readable storage medium for calculating the ultimate support force of an overconsolidated sandy clay tunnel face. The method comprises: determining model parameters based on indoor tests, determining equivalent strength parameters according to the model parameters and in combination with the strength criterion of overconsolidated sandy clay with coarse-grained strengthening effect; establishing a modified tunnel face collapse model according to the limit analysis theory; introducing the equivalent strength parameters of overconsolidated sandy clay into the modified tunnel face collapse model, and constructing a tunnel face collapse power equation; solving the tunnel face collapse power equation to obtain the ultimate support force, and drawing a recommended design diagram of tunnel face support force under different overconsolidation degrees and sand contents; determining the overconsolidation ratio and sand content of the soil during tunnel excavation, querying the recommended design diagram of tunnel face support force, and obtaining a support force design reference value. The present invention introduces the coarse-grained strengthening effect, constructs the strength criterion of over-consolidated sandy clay, and finally establishes a method for calculating the ultimate support force of the sandy clay tunnel face considering the over-consolidation degree and sand content. This method makes up for the defect that the traditional design process requires a large number of experiments to determine the mechanical parameters of the soil layer. The proposed model only needs to carry out two groups of indoor tests in advance, and the ultimate earth pressure of the tunnel face under different over-consolidation ratios and sand contents can be quickly calculated during the tunnel excavation process, which provides a theoretical basis and design reference for the construction of tunnel engineering in over-consolidated sandy clay layers, ensures construction safety, and improves construction efficiency.

[0047] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or terminal including the element.

[0048] Of course, those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware (such as a processor, a controller, etc.) through a computer program, and the program can be stored in a computer-readable storage medium that can be read by a computer, and the program can include the processes of the above-mentioned method embodiments when executed. The computer-readable storage medium can be a memory, a disk, an optical disk, etc.

[0049] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, characterized in that: The method for calculating the ultimate support force of the tunnel face in overconsolidated sandy clay includes: Determine model parameters based on indoor tests, and determine equivalent strength parameters based on the model parameters and the strength criterion for overconsolidated sandy clay combined with the coarse-grained strengthening effect; According to the limit analysis theory, a modified tunnel face collapse model is established; The equivalent strength parameters of overconsolidated sandy clay were introduced into the modified tunnel face collapse model, and the tunnel face collapse power equation was constructed. Solve the tunnel face collapse power equation to obtain the ultimate support force, and draw a recommended design diagram of the tunnel face support force under different overconsolidation degrees and sand contents; Determine the overconsolidation ratio and sand content of the soil during tunnel excavation, query the recommended design drawing of the tunnel face support force, and obtain the reference value of the support force design.

2. The method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face according to claim 1 is characterized in that: The model parameters include: the slope of the pure clay compression curve λ m , rebound curve slope κ m , compression parameters N m , the critical stress ratio of pure clay M m , overconsolidation strength parameters of pure clay β m , intergranular structure parameters η , static side pressure coefficient K 0 and the pore water pressure coefficient r u ; According to the model parameters and the strength criterion of overconsolidated sandy clay combined with the coarse-grained strengthening effect, the equivalent strength parameters are determined, specifically including: Using the strength criterion for overconsolidated sandy clay: ； in, ψ a Indicates the sand content, M m represents the critical state stress ratio of pure clay, β m represents the overconsolidation strength parameter of pure clay, λ m and κ m They represent the slope of the compression curve and the slope of the rebound curve of pure clay, q and p' deviatoric stress and mean effective stress, respectively. represents the initial consolidation pressure, ξ represents the structural variables used to describe the evolution of intergranular structure, ξ The calculation is: ； in, e a,min represents the minimum porosity of sand, φ a represents the sand volume fraction, η represents the inter-particle structure parameter; The equivalent strength parameter of the overconsolidated sandy clay is determined, wherein the equivalent strength parameter of the overconsolidated sandy clay adopts the Mohr-Coulomb equivalent strength parameter.

3. The method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face according to claim 2 is characterized in that: The determination of the equivalent strength parameters of overconsolidated sandy clay specifically includes: Calculation of Mohr-Coulomb equivalent strength parameters of overconsolidated sandy clay using the tangent method, including the internal friction angle φ' and cohesion c The slope of the tangent line to the strength criterion of sandy clay represents the tangent value of the internal friction angle tan φ' , the intercept is the cohesion c ; According to different consolidation states and overconsolidation ratios of soil, the corresponding internal friction angle and cohesion are: For soil without considering the consolidation state, the Mohr-Coulomb equivalent strength parameter is: ； ； For soils with an overconsolidation ratio greater than 2, the Mohr-Coulomb equivalent strength parameter of strongly overconsolidated soil is: ； ； in, A and B All are soil parameters; ； ； For soils with an overconsolidation ratio less than 2, the strength criterion for overconsolidated sandy clay is used for weakly overconsolidated soils and normally consolidated soils. The slope and intercept of the tangent line at / 2 represent the internal friction angle φ' and cohesion c .

4. The method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face according to claim 3 is characterized in that: According to the limit analysis theory, a modified tunnel face collapse model is established, which specifically includes: If the collapsed body is a rigid body and undergoes rotational failure around the horizontal direction perpendicular to the tunnel axis, and the center of rotation is point O, the cross section of the collapsed body and the tunnel connection coincides; Discretize the circular section of the tunnel into several pairs of left-right symmetrical points; Generate a plane consisting of the rotation center point and the left-right symmetric points from the bottom of the tunnel section to the top of the tunnel section; Add angle steps on the plane between the rotation center point and the left and right symmetrical points of the tunnel top to generate a new plane until the end point of the collapse surface.

5. The method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face according to claim 4 is characterized in that: The equivalent strength parameters of overconsolidated sandy clay are introduced into the modified tunnel face collapse model to construct the tunnel face collapse power equation, which specifically includes: The determined equivalent strength parameter of overconsolidated sandy clay is introduced into the friction power in the tunnel face power equation: ； in, W F represents the friction power in the tunnel face power equation, c and φ' They represent the cohesion and internal friction angle of sandy clay obtained by the tangent method, υ represents the unit velocity vector, S represents the surface area of ​​the modified tunnel face collapse model; The tunnel face collapse power equation is established based on the balance between external power and internal power, wherein the internal power includes gravity power and the external power includes friction power, support power and pore water pressure power; ； in, γ sat It represents the saturated density of soil. σ c represents the ultimate support force of the tunnel face, u is the pore water pressure, represents the volume strain increment of the soil skeleton, n represents the normal vector perpendicular to the failure plane, V Represents the volume of the collapsed model.

6. The method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face according to claim 5 is characterized in that: The method of solving the tunnel face collapse power equation to obtain the ultimate support force and drawing the tunnel face support force suggestion design diagram under different overconsolidation degrees and sand contents specifically includes: Solve the tunnel face collapse power equation and obtain the analytical solution of the tunnel face ultimate support force; Using MATLAB software and quadratic programming algorithm, the extreme value of the analytical solution of the ultimate support force of the tunnel face is obtained; In the MATLAB program, multiple extreme value points of the ultimate support force solution are obtained, and then the minimum value among all extreme value points is taken to obtain the global minimum value. The ultimate support force corresponding to the global minimum value is the design value. According to the model parameters, combined with the change of support force with overconsolidation ratio and sand content, the corresponding support force recommended design diagram is drawn.

7. The method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face according to claim 6 is characterized in that: Determining the overconsolidation ratio and sand content of the soil during tunnel excavation, querying the tunnel face support force recommended design drawing, and obtaining the support force design reference value specifically includes: The soil overconsolidation ratio and sand content were obtained through field tests during tunneling; Find the sand content on the recommended design drawing of tunnel face support force ψ a and intergranular structural parameters η The corresponding curve; The dimensionless pre-consolidation stress is determined according to the soil over-consolidation ratio parameter, and finally the design reference value of the support force is determined by the interpolation method.

8. A system for calculating the ultimate support force of an overconsolidated sandy clay tunnel face, characterized in that: The ultimate support force calculation system for the overconsolidated sandy clay tunnel face includes: A parameter determination module is used to determine the model parameters based on the indoor test, and determine the equivalent strength parameters according to the model parameters and the strength criterion of overconsolidated sandy clay combined with the coarse-grained strengthening effect; Model building module, used to build a modified tunnel face collapse model based on limit analysis theory; An equation building module is used to introduce the equivalent strength parameters of overconsolidated sandy clay into the modified tunnel face collapse model and construct the tunnel face collapse power equation; A design drawing module is used to solve the tunnel face collapse power equation, obtain the ultimate support force, and draw a recommended design drawing of the tunnel face support force under different overconsolidation degrees and sand contents; The support force query module is used to determine the overconsolidation ratio and sand content of the soil during tunnel excavation, query the recommended design drawing of the tunnel face support force, and obtain the support force design reference value.

9. A terminal, characterized in that: The terminal includes: a memory, a processor, and a program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face stored in the memory and executable on the processor. When the program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face is executed by the processor, the steps of the method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face. When the program for calculating the ultimate support force of an overconsolidated sandy clay tunnel face is executed by a processor, the steps of the method for calculating the ultimate support force of an overconsolidated sandy clay tunnel face as described in any one of claims 1 to 7 are implemented.

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