Shield tunnel underground butt joint section stratum partition reinforcement design method

Abstract

The invention relates to the technical field of geotechnical engineering curtain grouting-freezing, and discloses a shield tunnel underground butt-joint section stratum partition reinforcement design method which comprises the steps that a butt-joint strong-permeability stratum is divided into a contact seepage isolation area, a free face self-stabilization seepage-proofing area, a core bearing area and a frost heaving and thaw collapse improvement area; the grouting layer thickness and the grouting layer length of the contact seepage isolation area are determined; determining the grouting layer thickness and the grouting layer length of the free face self-stabilizing seepage-proofing area; determining the frozen soil layer thickness of the core bearing area according to the target frozen soil layer thickness; and based on the freezing thickness, the frost heaving rate and the thaw collapse rate, the frost heaving amount and the thaw collapse amount are calculated in combination with the frost heaving inhibition coefficient and the thaw collapse correction coefficient, and the freezing reinforcement thickness of the frost heaving and thaw collapse improved area is determined according to the frost heaving amount and the thaw collapse amount. According to the method, the seepage flow can be effectively reduced, and the problems of structural stability and seepage control in butt joint of high-permeability strata are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geotechnical engineering curtain grouting-freezing technology, in particular to a stratum partition reinforcement design method for shield tunnel ground docking section. BACKGROUND

[0002] In the construction of shield tunnel ground docking, strong permeable stratum faces core problems such as frost heaving deformation, contact seepage, stratum disturbance, and insufficient bearing capacity: single freezing method is easy to threaten the stability of shield structure due to frost heaving force (frost heaving rate 9%), and the heat disturbance of the cutterhead leads to the weak freezing area and causes the block seepage; single grouting method is difficult to form a reliable water stop curtain due to high water pressure permeation, and the bearing capacity of the grouting body lacks quantitative design standard. The existing technology cannot simultaneously meet the requirements of anti-seepage, anti-frost heaving, structural stability, and heat interference control, and there is an urgent need for a collaborative reinforcement method to solve the problems of seepage isolation in composite stratum, self-stability of the free surface, bearing optimization, and frost heaving and thawing settlement suppression.

[0003] Domestic and foreign scholars have carried out corresponding research on the reinforcement of surrounding rock and soil of shield docking, for example, the patent with application number CN202510568238.2 discloses a high-pressure water-rich environment shield ground docking surrounding rock reinforcement device and method, which can quickly adjust the freezing pipe arrangement strategy, effectively reducing the increase in time cost and construction progress delay caused by scheme changes; the patent with application number CN202411673739.9 discloses a grouting reinforcement device for shield docking middle part and its construction method, which uses high-pressure grouting equipment to inject cement slurry into the cracks of the surrounding rock and soil of the tunnel, effectively forming a stable and safe reinforcement zone; the patent with application number CN202411565283.4 discloses an in-situ test method based on shield docking curtain grouting, which achieves complete loop of slurry injection by each pipe by designing the number and length of the curtain grouting pipe layout, and uses the least number of curtain grouting pipes to make the surrounding rock grouting reinforcement range meet the design requirements; for example, the patent with application number CN202310787998.3 discloses a high water pressure and strong permeable stratum underwater docking reinforcement method, which forms a stable reinforcement zone by curtain grouting-freezing method to provide a stable water isolation boundary for tunnel breakthrough excavation; the patent with application number CN202310150990.6 discloses a construction method for shield ground docking in strong water-permeable sand stratum, which reinforces the surrounding rock and soil of the shield docking area by curtain freezing method to reduce the risk of instability and water seepage of the docking section excavation surface.

[0004] Although existing research has disclosed a small amount of related technical achievements, they are mostly focused on the upgrading and improvement of surrounding rock and soil reinforcement devices. Even though some research achievements disclose the reinforcement method or technology for the surrounding rock and soil of the docking section during the shield docking process, they do not define the detailed regional division of the stratum reinforcement system and the role of each region, resulting in a lack of targeted technical support for stratum reinforcement effect, and facing the following technical difficulties:

[0005] 1) The butt joint section of the shield needs to implement welding and cutting operations and release a large amount of heat during the excavation process. Based on the characteristics of the large thermal conductivity of steel, the heat generated by welding and cutting is easy to cause the melting of the interface between the shield shell and the frozen soil, forming a seepage channel, and there is a risk of leakage during the through excavation of the butt joint shield.

[0006] 2) Due to the influence of the disturbance of the through excavation of the butt joint shield, the strength and anti-seepage grade of the frozen soil body at the cut position are weakened, and there is a possibility of block falling or even seepage instability, which brings huge construction safety risks and huge psychological burden to the construction personnel.

[0007] 3) The design reinforcement range of the frozen soil body is mainly considered at the experience level, and no clear numerical and theoretical support is provided.

[0008] 4) The subsequent frost heaving and thawing effect is not considered during the reinforcement process, which makes the reinforcement method have drawbacks.

[0009] In view of the problems in the related art, no effective solution has been proposed so far. SUMMARY

[0010] In view of the problems in the related art, the present application proposes a ground stratum partition reinforcement design method for a butt joint section of a shield tunnel, to overcome the above technical problems existing in the prior art.

[0011] To this end, the specific technical solutions adopted by the present application are as follows:

[0012] A ground stratum partition reinforcement design method for a butt joint section of a shield tunnel, comprising the following steps:

[0013] S1, according to the preset reinforcement requirement, the strong seepage ground stratum of the butt joint section of the shield tunnel is divided into a contact seepage isolation zone, an empty surface self-stabilizing anti-seepage zone, a core bearing zone and a frost heaving and thawing improvement zone;

[0014] S2, based on the temperature diffusion radius and the melting zone radius, the thickness of the grouting layer of the contact seepage isolation zone is determined in combination with the correction coefficient, and the length of the grouting layer of the contact seepage isolation zone is determined according to the length of the butt joint shield body, the width of the butt joint shield cut and the preset reduction coefficient;

[0015] S3, according to the target thickness of the bending control and the shear control, the thickness of the grouting layer of the empty surface self-stabilizing anti-seepage zone is determined, and the length of the grouting layer of the empty surface self-stabilizing anti-seepage zone is determined based on the width of the butt joint shield cut and the lap length;

[0016] S4, the cross section of the frozen soil body is converted into an equivalent grouting body cross section, the target frozen soil body thickness is calculated based on the equivalent grouting body cross section in combination with the bending resistance, the shear resistance and the deformation control, and the thickness of the frozen soil layer of the core bearing zone is determined according to the target frozen soil body thickness.

[0017] S5, calculating the frost heave amount and thaw settlement amount based on the frozen thickness, the frost heave rate and the thaw settlement rate, combining the frost heave inhibition coefficient and the thaw settlement correction coefficient, and determining the frozen reinforcement thickness of the frost heave and thaw settlement improvement area according to the frost heave amount and the thaw settlement amount.

[0018] Further, the step of dividing the strong permeable stratum in the ground of the shield tunnel into the contact seepage isolation area, the free face self-stable anti-seepage area, the core bearing area and the frost heave and thaw settlement improvement area according to the preset reinforcement requirement comprises the following steps:

[0019] S11, dividing the junction between the shield body and the frozen soil into the contact seepage isolation area to isolate the seepage channel formed by the melting of the frozen soil due to the ambient temperature and local thermal operation;

[0020] S12, dividing the area of the shield butt joint cutter head cutout excavation contour into the free face self-stable anti-seepage area to provide self-standing and waterproof properties when exposed by excavation, preventing falling blocks and seepage;

[0021] S13, dividing the main frozen wall formed by artificial freezing into the core bearing area to provide key bearing capacity and overall water stop curtain;

[0022] S14, improving the soil body as the frost heave and thaw settlement improvement area by permeation grouting at the periphery of the frozen area to inhibit the frost heave and thaw settlement deformation in the freezing and thawing process.

[0023] Further, the step of determining the grouting layer thickness of the contact seepage isolation area based on the temperature diffusion radius and the thawing area radius, combining the correction coefficient, and determining the grouting layer length of the contact seepage isolation area according to the length of the butt joint shield body, the width of the butt joint shield cutter and the preset reduction coefficient comprises the following steps:

[0024] S21, determining the temperature distribution of each layer of material based on the temperature field solution under the radial steady-state heat conduction of the multi-layer material cylindrical wall to obtain the temperature at any position of each layer of material;

[0025] S22, determining the temperature diffusion radius according to the temperature at any position of each layer of material, combining the freezing point temperature position, and solving the transient temperature field under the heat conduction of a single point heat source of a multi-layer material flat plate;

[0026] S23, selecting the maximum value of the temperature diffusion radius and the thawing area radius under the transient temperature field as the initial grouting layer thickness, and correcting the initial grouting layer thickness combining the correction coefficient to obtain the corrected grouting layer thickness of the contact seepage isolation area;

[0027] S24, determining the grouting layer length of the contact seepage isolation area according to the length of the butt joint shield body, the width of the butt joint shield cutter and the preset reduction coefficient.

[0028] Further, the expression of the temperature at any position of each layer of material is:

[0029] ;

[0030] ;

[0031] ;

[0032] The grouting layer thickness expression of the contact seepage isolation zone after correction is:

[0033] ;

[0034] d1=Max[r,K];

[0035] ;

[0036] ;

[0037] The grouting layer length expression of the contact seepage isolation zone is:

[0038] L1=2x omega x L C +L D ;

[0039] In the formula, T r represents the temperature at any position of the i-th layer material, T i represents the inner surface temperature of the i-th layer material, T i+1 represents the outer surface temperature of the i-th layer material, r represents the temperature diffusion radius, r i represents the inner radius of the i-th layer material, r i+1 represents the outer radius of the i-th layer material, Q represents the total heat flow rate of the material, R i represents the radial thermal resistance of the i-th layer material, lambda i represents the thermal conductivity of the i-th layer material, L represents the material length, d 1xz The grouting layer thickness of the contact seepage isolation zone after correction, gamma represents the correction coefficient, d1 represents the initial grouting layer thickness, Max[r,K] represents the maximum value selected from the temperature diffusion radius r and the melting zone radius K, t represents time, rho represents material density, C represents material specific heat, delta T represents temperature difference, J represents material latent heat of fusion, L1 represents the grouting layer length of the contact seepage isolation zone, omega represents the reduction coefficient, L C represents the length of the butt shield, L D represents the butt shield cut width.

[0040] Further, the grouting layer thickness of the free face self-stabilizing anti-seepage zone is determined according to the target thickness of the bending resistance control and the shearing resistance control, and the grouting layer length of the free face self-stabilizing anti-seepage zone is determined based on the butt shield cut width and the lap length, including the following steps:

[0041] S31, determine the bending strength and shear strength of the grouting body of the free surface self-stabilization anti-seepage zone according to the material properties of the grouting layer and the test results;

[0042] S32, calculate the maximum bending moment and maximum shear force of the grouting body of the free surface self-stabilization anti-seepage zone based on the self-stability under construction disturbance and vibration effect, combined with dynamic load coefficient and local melting water storage weight;

[0043] S33, determine the minimum thickness of bending control and the minimum thickness of shear control of the free surface self-stabilization anti-seepage zone according to bending stress checking and shear stress checking, combined with the maximum bending moment and the maximum shear force of the grouting body;

[0044] S34, select the maximum value of the minimum thickness of bending control and the minimum thickness of shear control as the grouting layer thickness of the free surface self-stabilization anti-seepage zone, and determine the grouting layer length of the free surface self-stabilization anti-seepage zone combined with the butt joint shield cut width and lap length.

[0045] Further, the expression of the maximum bending moment and the maximum shear force of the grouting body of the free surface self-stabilization anti-seepage zone is:

[0046] ;

[0047] ;

[0048] The expression of the grouting layer thickness of the free surface self-stabilization anti-seepage zone is:

[0049] d2=Max[t M ,t V ];

[0050] ;

[0051] ;

[0052] The expression of the grouting layer length of the free surface self-stabilization anti-seepage zone is:

[0053] L2=L D +2ψ;

[0054] In the formula, M max represents the maximum bending moment of the grouting body of the free surface self-stabilization anti-seepage zone, V max represents the maximum shear force of the grouting body of the free surface self-stabilization anti-seepage zone, ξ represents the dynamic load coefficient, q s represents the local melting water storage weight, q t represents the weight of the grouting body of the free surface self-stabilization anti-seepage zone, L D represents the butt joint shield cut width, d2 represents the grouting layer thickness of the free surface self-stabilization anti-seepage zone, Max[t M , t Vrepresents the maximum value of t M and t V represents the maximum value of t M represents the minimum thickness of the anti-bending control of the self-stable anti-seepage zone of the free surface, t V represents the minimum thickness of the anti-shear control of the self-stable anti-seepage zone of the free surface, [σ] represents the bending strength of the grouting body of the self-stable anti-seepage zone of the free surface, [τ] represents the shear strength of the grouting body of the self-stable anti-seepage zone of the free surface, L2 represents the length of the grouting layer of the self-stable anti-seepage zone of the free surface, and ψ represents the lap length.

[0055] Further, the conversion of the frozen soil section into the equivalent grouting body section, the calculation of the target frozen soil thickness based on the equivalent grouting body section, the combination of the bending bearing capacity, the shear bearing capacity and the deformation control, and the determination of the frozen soil layer thickness of the core bearing zone according to the target frozen soil thickness comprise the following steps:

[0056] S41, determining the maximum bending moment and the maximum shear force of the core bearing zone according to the external load, and converting the frozen soil section into an equivalent grouting body section with a preset width and an unchanged thickness; based on the converted equivalent grouting body section, calculating the position of the equivalent section centroid axis and the moment of inertia;

[0057] S42, calculating the minimum frozen soil thicknesses of the bending control, the shear control and the deformation control based on the bending bearing capacity, the shear bearing capacity and the deformation control, and selecting the maximum value of the minimum frozen soil thicknesses of the bending control, the shear control and the deformation control as the frozen soil layer thickness of the core bearing zone;

[0058] When the bending stress equation is equal to the bending strength of the frozen soil, the minimum frozen soil thickness of the bending control of the core bearing zone is determined.

[0059] When the shear stress equation is equal to the shear strength of the frozen soil, the minimum frozen soil thickness of the shear control of the core bearing zone is determined.

[0060] When the deflection equation is equal to the allowable deflection of the grouting body, the minimum frozen soil thickness of the deformation control of the core bearing zone is determined.

[0061] Further, the expression of the maximum bending moment and the maximum shear force of the core bearing zone is:

[0062] ;

[0063] ;

[0064] The expression of the position of the equivalent section centroid axis and the moment of inertia is:

[0065] ;

[0066] ;

[0067] The expressions of the bending stress, shear stress and deflection equation are:

[0068] ;

[0069] ;

[0070] ;

[0071] The expression of the thickness of the frozen soil layer in the core bearing area is:

[0072] d3 = Max [h f1 , h f2 , h f3 ];

[0073] In the formula, M m represents the maximum bending moment of the core bearing area, V m represents the maximum shear force of the core bearing area, q z represents the total load of water and soil from the outside, L D represents the width of the shield cutout, y c represents the distance from the equivalent section centroid axis to the lower edge of the section, h g represents the thickness of the grouting layer of the free face self-stabilizing anti-seepage area, E f represents the elastic modulus of the frozen soil, E g represents the elastic modulus of the grouting body, h f represents the calculated thickness of the frozen soil, I e represents the equivalent section moment of inertia, I f represents the section moment of inertia of the frozen soil, I g represents the section moment of inertia of the grouting body, σ f represents the compressive stress at the top of the frozen soil, y t represents the distance from the equivalent section centroid axis to the top surface of the frozen soil, [f f ] represents the bending strength of the frozen soil, τ f represents the shear stress of the frozen soil, [τ f ] represents the shear strength of the frozen soil, S represents the static moment of the equivalent section above or below the equivalent section centroid axis to the equivalent section centroid axis, δ represents the deflection, [δ] represents the allowable deflection of the grouting body, d3 represents the thickness of the frozen soil layer in the core bearing area, Max [h f1 , h f2 , h f3 ] represents the maximum value selected from h f1 , h f2 , h f3 , h f1 represents the minimum frozen soil thickness controlled by bending, h f2 represents the minimum frozen soil thickness controlled by shear, h f3The minimum frozen soil thickness representing deformation control.

[0074] Further, the frost heaving amount and the thaw settlement amount are calculated based on the frozen thickness, the frost heaving rate and the thaw settlement rate, in combination with the frost heaving inhibition coefficient and the thaw settlement correction coefficient, and the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area is determined according to the frost heaving amount and the thaw settlement amount, and the method comprises the following steps:

[0075] S51, the frost heaving amount is calculated according to the frozen thickness and the frost heaving rate, in combination with the frost heaving inhibition coefficient, and the thaw settlement amount is determined based on the thaw settlement rate, the frozen thickness and the thaw settlement correction coefficient;

[0076] S52, the maximum value of the frost heaving amount and the thaw settlement amount is selected as the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area.

[0077] Further, the expression of the frost heaving amount is:

[0078] A = ɑ × η × H;

[0079] H = d 1xz +d3;

[0080] The expression of the thaw settlement amount is:

[0081] B = β × × H;

[0082] The expression of the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area is:

[0083] d4 = Max [A, B];

[0084] In the formula, A represents the frost heaving amount, ɑ represents the frost heaving inhibition coefficient, η represents the frost heaving rate, H represents the frozen thickness, d 1xz d3 represents the thickness of the frozen soil layer of the core bearing area, B represents the thaw settlement amount, β represents the thaw settlement correction coefficient, d4 represents the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area, and Max [A, B] represents the maximum value selected from A and B.

[0085] The beneficial effects of the present application are:

[0086] 1) The present application initiates the four-part design concept of the shield butt joint reinforcement area, which is clear in function and solves the inherent defects of single construction method.

[0087] 2) The present application provides a calculation method and formula for each subarea key design index (thickness, length, strength, temperature), which improves the design from experience to theoretical calculation level.

[0088] 3) The present application greatly improves the safety and reliability of the in-situ butt joint through thermal-mechanical multi-field coupling analysis, especially the quantitative evaluation of the heat insulation effect and bearing capacity of the grouting layer.

[0089] 4) The application effectively inhibits frost heaving and thawing settlement through IV zone grouting improvement, and reduces the influence on the surrounding environment. BRIEF DESCRIPTION OF DRAWINGS

[0090] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0091] Figure 1 It is a schematic diagram of shield ground-in-interface joint section ground partition reinforcement according to the ground-in-interface joint section ground partition reinforcement design method of the shield tunnel of the embodiment of the present application;

[0092] Figure 2 It is a schematic diagram of the process of converting the cross section of the frozen soil according to the ground-in-interface joint section ground partition reinforcement design method of the shield tunnel of the embodiment of the present application. DETAILED DESCRIPTION

[0093] In order to further illustrate the embodiments, the present application provides drawings which are part of the disclosure of the present application, mainly used to illustrate the embodiments, and can explain the operating principle of the embodiments in cooperation with the related description of the specification. Those skilled in the art should understand other possible embodiments and advantages of the present application by referring to these contents. The components in the drawings are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0094] According to the embodiment of the present application, a ground-in-interface joint section ground partition reinforcement design method of a shield tunnel is provided.

[0095] The present application is aimed at the above-mentioned problems existing in the prior art, overcomes the shortcomings of the prior art, and solves the four key technical problems of thermal interference, bearing, water stop and frost heaving and thawing settlement by using the "grouting-frozen" composite reinforcement method and dividing the reinforcement area into four functional partitions: I zone (contact seepage isolation zone), II zone (self-stable anti-seepage zone of free surface), III zone (core bearing zone), and IV zone (frost heaving and thawing settlement improvement zone). The steady-state / transient heat conduction problem of the multi-layer cylindrical wall (shield shell-grouting layer-frozen soil) is solved in combination with the temperature control equation and thermal resistance calculation, the position of the thawing line is determined, the thickness of the I zone grouting layer is determined, in addition, the great difference in seepage flow before and after the I zone grouting is quantitatively analyzed through seepage calculation, and the effectiveness of the grouting heat insulation is proved; based on the structural strength calculation results, the reinforcement thickness, length and other parameters of the II zone and III zone are determined; further considering the frost heaving and thawing settlement effect and combining the influence mechanism of permeation grouting, the permeation grouting range is determined.

[0096] The application will be further described in conjunction with the drawings and specific embodiments, as shown in Figures 1-2 The shield tunnel ground-in-ground butt joint segment stratum partition reinforcement design method according to the embodiment of the application comprises the following steps:

[0097] S1, according to a preset reinforcement requirement, a strong permeable stratum of a shield tunnel ground-in-ground butt joint is divided into a contact seepage isolation zone, a free face self-stabilization anti-seepage zone, a core bearing zone and a frost heaving and thawing settlement improvement zone;

[0098] The step of dividing the strong permeable stratum of the shield tunnel ground-in-ground butt joint into the contact seepage isolation zone, the free face self-stabilization anti-seepage zone, the core bearing zone and the frost heaving and thawing settlement improvement zone according to the preset reinforcement requirement comprises the following steps:

[0099] S11, a shield body and a frozen soil junction are divided into a zone I (contact seepage isolation zone), and the main function is to isolate the seepage channel formed by the melting of the frozen soil due to the environmental temperature and local thermal operation;

[0100] S12, a shield butt joint cutter head cutting contour vicinity is divided into a zone II (free face self-stabilization anti-seepage zone), and the main function is to provide self-standing and waterproof properties when exposed by excavation, to prevent falling blocks and water seepage;

[0101] S13, a main frozen wall formed by artificial freezing is divided into a zone III (core bearing zone), and the main function is to provide main bearing capacity and overall water stop curtain;

[0102] S14, the soil body outside the frozen zone is improved as a zone IV (frost heaving and thawing settlement improvement zone) by permeation grouting, and the main function is to inhibit the frost heaving and thawing settlement deformation in the freezing and thawing processes.

[0103] Specifically, as shown in Figure 1 It is a shield ground-in-ground butt joint partition reinforcement schematic diagram, Figure 1 The division basis of the four zones is as follows: zone I: the voids around the shield body are filled by radial grouting and advanced grouting when the shield stops, to form a slurry wrapping effect; zone II: the shield mud water tank is filled with mortar, and the curtain grouting is used to reinforce the large range of rock-soil body around the butt joint cutting position; zone III: the curtain freezing is used to further reinforce the rock-soil body around the shield body by the cold process in the curtain grouting zone; zone IV: the outermost side of the frozen area to the outermost side of the curtain grouting area is used as a frozen stress effect release zone and a frost heaving and thawing settlement improvement zone.

[0104] S2, the grouting layer thickness of the contact seepage isolation zone is determined based on the temperature diffusion radius and the thawing zone radius, in combination with a correction coefficient, and the grouting layer length of the contact seepage isolation zone is determined according to the butt joint shield length, the butt joint shield cutting width and a preset reduction coefficient;

[0105] The process of determining the grouting layer thickness of the contact seepage isolation zone based on the temperature diffusion radius and melting zone radius, combined with a correction coefficient, and determining the grouting layer length of the contact seepage isolation zone according to the length of the docking shield, the width of the docking shield cut, and a preset reduction coefficient includes the following steps:

[0106] S21. Solve the temperature field based on the radial steady-state heat conduction of the multi-layer material cylindrical wall to determine the temperature distribution of each layer of material and obtain the temperature at any position of each layer of material.

[0107] Specifically, the radial thermal resistance of each layer of material is determined based on the thermal conductivity, diffusion radius, and material length:

[0108] ;

[0109] Determine the interface temperature of each material layer based on the total heat flow rate and radial thermal resistance:

[0110] ;

[0111] Determine the temperature T at any location in each layer of material. r :

[0112] ;

[0113] In the formula, T r T represents the temperature at any location in the i-th layer of material. i T represents the inner surface temperature of the i-th layer of material. i+1 Let r represent the outer surface temperature of the i-th layer of material, and r represent the temperature diffusion radius. i Let r represent the inner radius of the i-th layer of material. i+1 Let R represent the outer radius of the i-th layer of material, Q represent the total heat flux of the material, and R represent the total heat flux of the material. i λ represents the radial thermal resistance of the i-th layer material. i Let L represent the thermal conductivity of the i-th layer of material, and L represent the length of the material.

[0114] S22. Based on the temperature at any location of each layer of material, combined with the freezing point temperature (T) r =0) Determine the temperature diffusion radius and solve the transient temperature field under the conduction of a single heat source in a multi-layered flat plate material;

[0115] Specifically, calculate the temperature diffusion radius:

[0116] ;

[0117] Determine the radius of the melting zone under a transient temperature field based on the law of energy conservation:

[0118] ;

[0119] In the formula, K represents the radius of the melting zone, t represents time, p represents the density of the material, C represents the specific heat of the material, AT represents the temperature difference, and J represents the latent heat of fusion of the material.

[0120] S23, select the maximum value of the temperature diffusion radius and the melting zone radius under the transient temperature field as the initial grouting layer thickness, consider the influence of the theoretical deviation on the initial grouting layer thickness, introduce a correction coefficient, and correct the initial grouting layer thickness combined with the correction coefficient to obtain the grouting layer thickness of the modified contact seepage isolation zone.

[0121] Specifically, the grouting layer thickness expression of the modified contact seepage isolation zone is:

[0122]

[0123] d1=Max[r,K];

[0124] In the formula, d 1xz The grouting layer thickness of the modified contact seepage isolation zone, γ represents the correction coefficient, the value range is 1.1~1.2, d1 represents the initial grouting layer thickness, Max[r, K] represents selecting the temperature diffusion radius r and the melting zone radius;

[0125] S24, according to the length of the butt shield, the butt shield cut width and the preset reduction coefficient, determine the grouting layer length of the contact seepage isolation zone.

[0126] Specifically, the grouting layer length expression of the contact seepage isolation zone is:

[0127] L1=2×ω×L C +L D ;

[0128] In the formula, L1 represents the grouting layer length of the contact seepage isolation zone, ω represents the reduction coefficient, the value range is 2 / 3~3 / 4, L C represents the length of the butt shield, and L D represents the butt shield cut width.

[0129] S3, according to the target thickness of the bending control and the shear control, determine the grouting layer thickness of the free face self-stabilizing anti-seepage zone, and based on the butt shield cut width and the lap length, determine the grouting layer length of the free face self-stabilizing anti-seepage zone.

[0130] The grouting layer thickness of the free face self-stabilizing anti-seepage zone is determined according to the target thickness of the bending control and the shear control, and the grouting layer length of the free face self-stabilizing anti-seepage zone is determined based on the butt shield cut width and the lap length, comprising the following steps:

[0131] ​S31, according to the material properties of the grouting layer and the test results, the bending strength and the shear strength of the grouting body of the free surface self-stabilization anti-seepage area are determined;

[0132] S32, based on the self-stability under construction disturbance and vibration effect, combined with the dynamic load coefficient and the local melting water storage weight, the maximum bending moment and the maximum shear force of the grouting body of the free surface self-stabilization anti-seepage area are calculated;

[0133] Specifically, the expression of the maximum bending moment and the maximum shear force of the grouting body of the free surface self-stabilization anti-seepage area is:

[0134] ;

[0135] ;

[0136] In the formula, M max represents the maximum bending moment of the grouting body of the free surface self-stabilization anti-seepage area, V max represents the maximum shear force of the grouting body of the free surface self-stabilization anti-seepage area, ξ represents the dynamic load coefficient, q s represents the local melting water storage weight, q t represents the weight of the grouting body of the free surface self-stabilization anti-seepage area;

[0137] S33, according to the bending stress checking and the shear stress checking, combined with the maximum bending moment and the maximum shear force of the grouting body, the minimum thickness of the bending control and the minimum thickness of the shear control of the free surface self-stabilization anti-seepage area are determined;

[0138] Specifically, according to the bending stress checking and the shear stress checking, the thickness value range of the grouting body of the free surface self-stabilization anti-seepage area under the most unfavorable internal force condition is determined:

[0139] ;

[0140] ;

[0141] In the formula, t M represents the minimum thickness of the bending control of the free surface self-stabilization anti-seepage area, t V represents the minimum thickness of the shear control of the free surface self-stabilization anti-seepage area, [σ] represents the bending strength of the grouting body of the free surface self-stabilization anti-seepage area, and [τ] represents the shear strength of the grouting body of the free surface self-stabilization anti-seepage area;

[0142] S34, the maximum value of the minimum thickness of the bending control and the minimum thickness of the shear control is selected as the thickness of the grouting layer of the free surface self-stabilization anti-seepage area, and combined with the butt joint shield cut width and the lap length, the length of the grouting layer of the free surface self-stabilization anti-seepage area is determined.

[0143] Specifically, the expression of the thickness of the grouting layer of the free surface self-stabilization anti-seepage area is:

[0144] d2=Max[tM , t V ];

[0145] The expression of the length of the grouting layer of the self-stabilizing anti-seepage zone of the free surface is:

[0146] L2=L D +2ψ;

[0147] In the formula, d2 represents the thickness of the grouting layer of the self-stabilizing anti-seepage zone of the free surface, d2=h g , Max[t M , t V ] represents the maximum value selected from t M and t V , L2 represents the length of the grouting layer of the self-stabilizing anti-seepage zone of the free surface, and ψ represents the lap length, which is in the range of 0.3 to 0.4.

[0148] S4, converting the frozen soil section into an equivalent grouting section, calculating the target frozen soil thickness based on the equivalent grouting section, combining the bending bearing capacity, the shear bearing capacity and the deformation amount control, and determining the thickness of the frozen soil layer of the core bearing area according to the target frozen soil thickness;

[0149] The method comprises the following steps:

[0150] S41, determining the maximum bending moment and the maximum shear force of the core bearing area according to the external load, and converting the frozen soil section into an equivalent grouting section with a preset width and an unchanged thickness; based on the converted equivalent grouting section, calculating the position of the equivalent section centroid axis and the moment of inertia;

[0151] The equivalent section represents the section of the whole grouting-frozen body after being equivalent, such as Figure 2 the right side of all sections, and the equivalent grouting section represents the section of the upper frozen body equivalent into a grouting body alone, such as Figure 2 the upper half of the grouting body on the right side.

[0152] Specifically, the most unfavorable internal force (the maximum bending moment M m , the maximum shear force V m ) is determined according to the external load, and the following relationship is satisfied:

[0153] ;

[0154] ;

[0155] In the formula, M m represents the maximum bending moment of the core bearing area, Vm q represents the maximum shear force of the core bearing area z q represents the total load of water and soil from the outside world

[0156] The grouting body-frozen soil body is the core bearing body of the core bearing area, but due to the difference in elastic modulus between the grouting body and the frozen soil body, the bearing capacity and deformation calculation need to be converted by equivalent section, such as Figure 2 , the frozen soil section is adjusted to an equivalent grouting body section with the same thickness and a width of L D *E f / E g ;

[0157] The position of the equivalent section centroid axis and the calculation of the moment of inertia satisfy the following relationship:

[0158] ;

[0159] ;

[0160] In the formula, y c represents the distance from the equivalent section centroid axis to the lower edge of the section, h g represents the thickness of the grouting layer of the self-stable anti-seepage area, E f represents the elastic modulus of the frozen soil body, E g represents the elastic modulus of the grouting body, h f represents the calculated thickness of the frozen soil body, which is the initially determined calculated thickness of the frozen soil body, I e represents the moment of inertia of the equivalent section, I f represents the moment of inertia of the frozen soil section, I g represents the moment of inertia of the grouting section, wherein the moment of inertia of the frozen soil section and the moment of inertia of the grouting section are determined by the distance from the equivalent section centroid axis to the lower edge of the section;

[0161] S42, based on the bending resistance, shear resistance and deformation control, the minimum frozen soil thickness of the bending control, shear control and deformation control is calculated, and the maximum value of the minimum frozen soil thickness of the bending control, shear control and deformation control is selected as the frozen soil layer thickness of the core bearing area;

[0162] Specifically, the minimum frozen soil thickness is solved according to the bending resistance, shear resistance and deformation control:

[0163] When the bending stress equation is equal to the bending strength of the frozen soil, the minimum frozen soil thickness of the bending control of the core bearing area is solved by computer:

[0164] ;

[0165] In the formula, σ f represents the compressive stress at the top of the frozen soil, y t[f] represents the distance from the centroidal axis of the equivalent cross section to the top surface of the frozen soil mass. f [Indicates the flexural strength of frozen soil;]

[0166] When the shear stress equation equals the shear strength of the frozen soil, the minimum frozen soil thickness controlled by the shear strength of the core bearing zone is determined by computer:

[0167] ;

[0168] In the formula, τ f Represents the shear stress in frozen soil, [τ] f The shear strength of frozen soil, where S represents the static moment of the equivalent section above or below the centroidal axis of the equivalent section about the centroidal axis of the equivalent section;

[0169] When the deflection equation equals the allowable deflection of the grouting body, the minimum frozen soil thickness controlled by the deformation of the core bearing zone is determined by computer:

[0170] ;

[0171] In the formula, δ represents deflection, and [δ] represents the allowable deflection of the grouting body.

[0172] Determine the thickness of the permafrost layer in the core bearing area:

[0173] d3=Max[h f1 h f2 h f3 ];

[0174] In the formula, d3 represents the thickness of the permafrost layer in the core bearing area, Max[h f1 h f2 h f3 ] indicates selecting h f1 h f2 h f3 The maximum value in h f1 h represents the minimum frozen soil thickness for bending resistance control. f2 h represents the minimum thickness of frozen soil mass that controls shear strength. f3 This indicates the minimum thickness of the frozen soil body for deformation control.

[0175] In this embodiment, the thickness h of the frozen soil in the core bearing area f It is obtained by solving three independent design criteria (bending stress, shear stress, and deflection), each criterion corresponding to an equation, and the key geometric parameter y in these equations is... t I e Both S and S are functions of the permafrost thickness. Specifically:

[0176] 1) y tThis represents the distance from the centroidal axis of the equivalent cross-section to the top surface of the frozen soil mass, that is, the vertical distance from the centroidal axis of the equivalent cross-section to the outermost edge of the frozen soil layer. Its value changes with the position of the centroidal axis, while the position of the centroidal axis (y)... c It is determined by the grouting thickness h. g and the thickness of the frozen soil h f Joint decision;

[0177] 2) I e The equivalent cross-sectional moment of inertia is obtained by superimposing the moments of inertia of the grouting section and the frozen soil section after parallel axis shifting (I). e =I g +I f The moment of inertia and its axis-shifting term in the frozen part both include h. f The higher-order terms make I e Become h f Complex functions;

[0178] 3) S represents the static moment of the equivalent section above or below the centroidal axis of the equivalent section about the centroidal axis of the equivalent section, which is the static moment (area moment) of the frozen soil layer about the centroid of the composite section. It is calculated as the product of the frozen soil area and the distance from its centroid to the composite centroid, and also varies with h. f change;

[0179] Wherein, parameter y t I e S and h f The non-linear relationship between them is as follows:

[0180] ;

[0181] Because of these parameters (y t I e 、S) and h f There is a nonlinear relationship between the three design equations (bending stress equation σ). f =0, shear stress equation τ f =0 and the deflection equation δ=0 are both about h f The implicit equations cannot be directly expressed as explicit analytical solutions. Therefore, in practical design, it is necessary to solve each equation separately using numerical iteration methods to obtain the minimum frozen soil thickness that satisfies the bending, shear, and deflection criteria, denoted as h, respectively. f1 h f2 and h f3 That is, respectively to h f The value of h is assigned to the three governing equations (bending stress equation, shear stress equation, and deflection equation). f1 h f2 h f3 The three values ​​can be obtained, and the final design of the frozen soil layer thickness d3 in the core bearing area is to take the maximum value of the three values.

[0182] S5, calculating the frost heaving amount and the thaw settlement amount based on the frozen thickness, the frost heaving rate and the thaw settlement rate, in combination with the frost heaving inhibition coefficient and the thaw settlement correction coefficient, and determining the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area according to the frost heaving amount and the thaw settlement amount.

[0183] The method comprises the following steps:

[0184] S51, calculating the frost heaving amount according to the frozen thickness and the frost heaving rate, in combination with the frost heaving inhibition coefficient, and determining the thaw settlement amount based on the thaw settlement rate, the frozen thickness and the thaw settlement correction coefficient;

[0185] Specifically, the expression of the frost heaving amount is:

[0186] A = a x η x H;

[0187] H = d 1xz + d3;

[0188] In the formula, A represents the frost heaving amount, a represents the frost heaving inhibition coefficient, the value range of which is 0.4-0.6, η represents the frost heaving rate, the value range of which is 1%-3%, H represents the frozen thickness, d 1xz The grouting layer thickness of the contact seepage isolation area after correction;

[0189] The expression of the thaw settlement amount is:

[0190] B = β x x H;

[0191] In the formula, B represents the thaw settlement amount, β represents the thaw settlement correction coefficient, the value range of which is 0.3-0.5, η represents the thaw settlement rate, the value range of which is 0.8%-2%;

[0192] S52, selecting the maximum value of the frost heaving amount and the thaw settlement amount as the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area;

[0193] Specifically, the frost heaving and thaw settlement improvement area is determined to be beyond the frozen reinforcement range:

[0194] d4 = Max [A, B];

[0195] In the formula, d4 represents the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area, and Max [A, B] represents the maximum value selected from A and B.

[0196] The present application controls stratum performance by grouting-freezing synergy: I area (contact seepage isolation area), grouting layer is used to reduce thermal conductivity, inhibit permafrost melting caused by ambient temperature and local thermal operation (such as cutting), combine with heat conduction model to control melting thickness, and eliminate seepage channel; II area (self-stable anti-seepage area of free surface), provide bearing anti-seepage layer with unconfined strength ≥4.0 MPa and permeability coefficient ≤2×10 -6 cm / s through grouting body; III area (core bearing area), provide main bearing capacity through freezing wall, and optimize thickness through stratum-structure model; IV area (frost heaving and thawing settlement improvement area), carry out grouting outside the freezing area, inhibit water migration through pore filling (filling rate 15%-30%) and permeability coefficient reduction (10 -3 -10 -5 cm / s), reduce frost heaving rate to 0.5%-1.5% and thawing settlement rate to 0.3%-1.2%. The method realizes seepage flow reduction by 2.7 million times, and solves the problems of structure stability and seepage control in high-permeability stratum connection.

[0197] The above merely describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for ground partition reinforcement design of a shield tunnel in-ground butt joint section, characterized in that, The method comprises the following steps: S1, according to the preset reinforcement requirement, the strong permeable stratum in the ground of the shield tunnel is divided into a contact seepage isolation zone, an air face self-stabilizing anti-seepage zone, a core bearing zone and a frost heaving and thawing settlement improvement zone; S2, based on the temperature diffusion radius and the thawing zone radius, the thickness of the grouting layer of the contact seepage isolation zone is determined in combination with a correction coefficient, and the length of the grouting layer of the contact seepage isolation zone is determined according to the length of the butt joint shield body, the width of the butt joint shield cutting and a preset reduction coefficient; S3, according to the target thickness of the bending resistance control and the shear resistance control, the thickness of the grouting layer of the air face self-stabilizing anti-seepage zone is determined, and the length of the grouting layer of the air face self-stabilizing anti-seepage zone is determined based on the width of the butt joint shield cutting and the lap length; S4, the cross section of the frozen soil body is converted into an equivalent grouting body cross section, the target frozen soil body thickness is calculated based on the equivalent grouting body cross section in combination with the bending resistance, the shear resistance and the deformation control, and the thickness of the frozen soil layer of the core bearing zone is determined according to the target frozen soil body thickness; S5, based on the freezing thickness, the frost heaving rate and the thawing settlement rate, the frost heaving amount and the thawing settlement amount are calculated in combination with the frost heaving inhibition coefficient and the thawing settlement correction coefficient, and the freezing reinforcement thickness of the frost heaving and thawing settlement improvement zone is determined according to the frost heaving amount and the thawing settlement amount.

2. The ground stratum partition reinforcement design method for a shield tunnel in-situ butt joint section according to claim 1, characterized in that, The method of dividing the strong permeable stratum in the ground of the shield tunnel into the contact seepage isolation zone, the air face self-stabilizing anti-seepage zone, the core bearing zone and the frost heaving and thawing settlement improvement zone according to the preset reinforcement requirement comprises the following steps: S11, the junction of the shield body and the frozen soil is divided into the contact seepage isolation zone to isolate the seepage channel formed by the thawing of the frozen soil due to the ambient temperature and the local thermal operation; S12, the cutting excavation contour region of the shield butt joint cutter head is divided into the air face self-stabilizing anti-seepage zone to provide the self-standing property and the waterproof property when being exposed by excavation, prevent the block falling and the water seepage; S13, the main frozen wall formed by the artificial freezing is divided into the core bearing zone to provide the key bearing capacity and the overall water stop curtain; S14, the soil body outside the freezing zone is improved by the permeation grouting as the frost heaving and thawing settlement improvement zone to inhibit the frost heaving and thawing settlement deformation in the freezing and thawing processes.

3. The method according to claim 1, characterized in that, The method of determining the thickness of the grouting layer of the contact seepage isolation zone based on the temperature diffusion radius and the thawing zone radius in combination with a correction coefficient and determining the length of the grouting layer of the contact seepage isolation zone according to the length of the butt joint shield body, the width of the butt joint shield cutting and a preset reduction coefficient comprises the following steps: S21, based on the temperature field solution under the radial steady-state heat conduction of the multi-layer material cylinder wall, the temperature distribution of each layer of material is determined to obtain the temperature of each layer of material at any position; S22, according to the temperature of each layer of material at any position, the temperature diffusion radius is determined in combination with the freezing point temperature position, and the transient temperature field under the heat conduction of a single point heat source of a multi-layer material flat plate is solved; S23, the maximum value of the temperature diffusion radius and the thawing zone radius under the transient temperature field is selected as the initial grouting layer thickness, and the initial grouting layer thickness is corrected in combination with the correction coefficient to obtain the corrected grouting layer thickness of the contact seepage isolation zone; S24, the length of the grouting layer of the contact seepage isolation zone is determined according to the length of the butt joint shield body, the width of the butt joint shield cutting and a preset reduction coefficient.

4. The ground stratum partition reinforcement design method for a ground face joint section of a shield tunnel according to claim 3, characterized in that, The expression of the temperature of each layer of material at any position is: ； ； ； The expression of the thickness of the grouting layer of the contact seepage isolation zone after the correction is: ； d1=Max[r, K]; ； ； The expression of the length of the grouting layer of the contact seepage isolation zone is: L1 = 2 x ω x L C + L D ; where T r represents the temperature at any position of the i-th layer material, T i represents the inner surface temperature of the i-th layer material, T i+1 represents the outer surface temperature of the i-th layer material, r represents the temperature diffusion radius, r i represents the inner radius of the i-th layer material, r i+1 represents the outer radius of the i-th layer material, Q represents the total heat flow rate of the material, R i represents the radial thermal resistance of the i-th layer material, λ i represents the thermal conductivity of the i-th layer material, L represents the material length, d 1xz the grouting layer thickness of the contact seepage isolation zone after correction, γ represents the correction coefficient, d1 represents the initial grouting layer thickness, Max[r, K] represents the maximum value selected from the temperature diffusion radius r and the melting zone radius K, t represents time, ρ represents the material density, C represents the specific heat of the material, ΔT represents the temperature difference, J represents the latent heat of fusion of the material, L1 represents the grouting layer length of the contact seepage isolation zone, ω represents the reduction coefficient, L C represents the length of the docking shield, L D represents the width of the docking shield cut.

5. The method according to claim 1, wherein, The method for determining the thickness of the grouting layer of the free surface self-stabilizing anti-seepage zone according to the target thickness controlled by the bending resistance and the shear resistance, and determining the length of the grouting layer of the free surface self-stabilizing anti-seepage zone based on the butt-joint shield cut width and the lap length comprises the following steps: S31, determining the bending strength and the shear strength of the grouting body of the free surface self-stabilizing anti-seepage zone according to the material properties and the test results of the grouting layer; S32, calculating the maximum bending moment and the maximum shear force of the grouting body of the free surface self-stabilizing anti-seepage zone based on the self-stability under the construction disturbance and the vibration effect, combining the dynamic load coefficient and the local melting water storage weight; S33, determining the minimum thickness controlled by the bending resistance and the minimum thickness controlled by the shear resistance of the free surface self-stabilizing anti-seepage zone according to the bending stress checking and the shear stress checking, combining the maximum bending moment and the maximum shear force of the grouting body; S34, selecting the maximum value of the minimum thickness controlled by the bending resistance and the minimum thickness controlled by the shear resistance as the thickness of the grouting layer of the free surface self-stabilizing anti-seepage zone, and determining the length of the grouting layer of the free surface self-stabilizing anti-seepage zone combining the butt-joint shield cut width and the lap length.

6. The ground stratum partition reinforcement design method for a shield tunnel in-situ butt joint section according to claim 5, characterized in that, The expression of the maximum bending moment and the maximum shear force of the grouting body of the free surface self-stabilizing anti-seepage zone is: ； ； The expression of the thickness of the grouting layer of the free surface self-stabilizing anti-seepage zone is: d2 = Max[t M , t V ]; ； ； The expression of the length of the grouting layer of the free surface self-stabilizing anti-seepage zone is: L2 = L D + 2ψ; In the formula, M max represents the maximum bending moment of the grouting body of the self-stabilizing anti-seepage area of the open face, V max represents the maximum shear force of the grouting body of the self-stabilizing anti-seepage area of the open face, ξ represents a dynamic load coefficient, q s represents the weight of the local melting water storage, q t represents the weight of the grouting body of the self-stabilizing anti-seepage area of the open face, L D represents the butt joint shield cut width, d2 represents the grouting layer thickness of the self-stabilizing anti-seepage area of the open face, Max[t M , t V ] represents the maximum value selected from t M and t V , t M represents the minimum thickness of the bending control of the self-stabilizing anti-seepage area of the open face, t V represents the minimum thickness of the shear control of the self-stabilizing anti-seepage area of the open face, [σ] represents the bending strength of the grouting body of the self-stabilizing anti-seepage area of the open face, [τ] represents the shear strength of the grouting body of the self-stabilizing anti-seepage area of the open face, L2 represents the grouting layer length of the self-stabilizing anti-seepage area of the open face, and ψ represents the lap length.

7. The method according to claim 1, wherein, The method for converting the frozen soil body section into an equivalent grouting body section, calculating the target frozen soil body thickness based on the equivalent grouting body section, combining the bending resistance, the shear resistance and the deformation amount control, and determining the frozen soil layer thickness of the core bearing zone according to the target frozen soil body thickness comprises the following steps: S41, determining the maximum bending moment and the maximum shear force of the core bearing zone according to the external load, and converting the frozen soil body section into an equivalent grouting body section with the same thickness and a preset width; calculating the equivalent section centroid axis position and the moment of inertia based on the converted equivalent grouting body section; S42, calculating the minimum frozen soil body thickness controlled by the bending resistance, the shear resistance and the deformation control based on the bending resistance, the shear resistance and the deformation amount control, and selecting the maximum value of the minimum frozen soil body thickness controlled by the bending resistance, the shear resistance and the deformation control as the frozen soil layer thickness of the core bearing zone; When the bending stress equation is equal to the bending strength of the frozen soil body, the minimum frozen soil body thickness controlled by the bending resistance of the core bearing zone is determined; When the shear stress equation is equal to the shear strength of the frozen soil body, the minimum frozen soil body thickness controlled by the shear resistance of the core bearing zone is determined; When the deflection equation is equal to the allowable deflection of the grouting body, the minimum frozen soil body thickness controlled by the deformation of the core bearing zone is determined.

8. The method according to claim 7, characterized in that, The expression of the maximum bending moment and the maximum shear force of the core bearing zone is: ； ； The expression of the equivalent section centroid axis position and the moment of inertia is: ； ； The expression of the bending stress, the shear stress and the deflection equation is: ； ； ； The expression of the frozen soil layer thickness of the core bearing zone is: d3 = Max [h f1 , h f2 , h f3 ] ; M = M m M = M m M = M z M = M D M = M c M = M g M = M f M = M g M = M f M = M e M = M f M = M g M = M f M = M t M = M f M = M f M = M f M = M f1 M = M f2 M = M f3 M = M f1 M = M f2 M = M f3 M = M f1 M = M f2 M = M f3 M = M 9. The method of claim 1, wherein, The method for calculating the frost heaving amount and the thaw settlement amount based on the frozen thickness, the frost heaving rate and the thaw settlement rate, combining the frost heaving inhibition coefficient and the thaw settlement correction coefficient, and determining the frozen reinforcement thickness of the frost heaving and thaw settlement improvement zone according to the frost heaving amount and the thaw settlement amount comprises the following steps: S51, according to the frozen thickness and the frost heaving rate, the frost heaving amount is calculated in combination with the frost heaving inhibition coefficient, and the thaw settlement amount is determined based on the thaw settlement rate, the frozen thickness and the thaw settlement correction coefficient; S52, the maximum value of the frost heaving amount and the thaw settlement amount is selected as the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area.

10. The method according to claim 9, wherein, The expression of the frost heaving amount is: A=ɑ×η×H; H = d 1xz + d3; The expression of the thaw settlement amount is: B = β x x H; The expression of the frozen reinforcement thickness of the frost heaving and thaw settlement improvement area is: d4=Max[A、B]; In the formula, A represents the frost heaving amount, a represents the frost heaving inhibition coefficient, η represents the frost heaving rate, H represents the frozen thickness, d 1xz The grouting layer thickness of the modified contact seepage isolation zone is d3, the frozen soil layer thickness of the core bearing zone is d, B represents the thawing settlement amount, β represents the thawing settlement correction coefficient, represents the thawing settlement rate, d4 represents the frozen reinforcement thickness of the frost heaving and thawing settlement improvement zone, and Max[A, B] represents the maximum value selected from A and B.

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