Method for evaluating and controlling response of shield butt joint close approach excavation superimposed disturbance

Abstract

The application discloses a method for evaluating and controlling the response of a shield to the close excavation superimposed disturbance, and relates to the technical field of shield tunnel construction, which comprises the following steps: constructing a multidimensional information database of stratum conditions in the docking area; the multidimensional information database comprises stratum parameters of the docking section, shield excavation parameters and spatiotemporal parameters during docking, and is used for extracting the mechanical behavior characteristics of the preceding shield and the mechanical behavior characteristics of the following shield; based on the multidimensional information database, the structural resistance of the preceding shield is analyzed, and the additional load borne by the preceding shield is determined according to the additional load generated by the excavation of the following shield and the initial stress field around the preceding shield; according to the structural resistance of the preceding shield and the additional load borne by the preceding shield, a response evaluation system of the load and resistance ratio is established to determine the disturbance level, and micro-disturbance control measures are adopted according to the disturbance level determination result. The application can solve the problems of displacement overrun of the preceding shield and tunnel instability risk caused by the complex evolution of the additional stress field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of shield tunnel construction, in particular to a shield butt joint near-joint tunneling superimposed disturbance response evaluation and control method. BACKGROUND

[0002] With the development of urban underground space, the application of shield tunnel construction technology in complex geological conditions is becoming more and more widespread. Shield tunnel butt joint construction is an important engineering technology, which is often used to solve the problem of long-distance tunnel connection and existing line crossing construction. Especially for composite strata with poor permeability, the stratum disturbance, additional load transfer and structure response problems during the near-joint tunneling of the trailing shield are extremely complex. In such cases, the displacement of the leading shield may exceed the limit due to the near-joint tunneling of the trailing shield, and even lead to the risk of tunnel instability, which seriously affects the safety and economy of the project.

[0003] The existing shield butt joint technology faces many challenges in strata with significant permeability differences or complex hydrogeological conditions. In engineering practice, the additional stress field caused by the tunneling of the trailing shield is complex, and the disturbed load distribution of the leading shield is not clear, lacking effective control technology. This leads to risks such as stratum instability, shield displacement, and tunnel collapse in actual projects, resulting in high engineering costs and serious safety hazards. Moreover, traditional shield butt joint technology relies heavily on experience and parameter adjustment, lacking a systematic evaluation and control method.

[0004] The existing technology has three main shortcomings: first, the overall research foundation in the field of shield butt joint is weak, with few public achievements, and there is still a lack of systematic theoretical and methodological system; second, existing control technology relies heavily on experience and parameter adjustment, and there is a lack of dynamic load calculation method based on time and space effect, and insufficient consideration of the relationship between shield downtime and stratum permeability, leading to uncontrollable disturbed displacement of the leading shield; third, in domestic and foreign cases, the superimposed effect of indirect conduction load between strata (stratum conduction) and instantaneous collision load (collision impact) has not been systematically studied, making it difficult to accurately evaluate and control the disturbance during shield butt joint construction. These technical deficiencies make it difficult to achieve accurate disturbance evaluation and effective control in shield butt joint projects, thereby restricting the safety and economy of shield butt joint projects.

[0005] In view of the problems in the related art, no effective solutions have been proposed so far. SUMMARY

[0006] In view of the problems in the related art, the present application proposes a shield butt joint near-joint tunneling superimposed disturbance response evaluation and control method, which has the advantages of accurately predicting the disturbed load of the leading shield and achieving micro-disturbance control, thereby solving the problem of inaccurate disturbance evaluation and inaccurate control in the prior art of shield butt joint near-joint tunneling.

[0007] To this end, the specific technical solutions adopted by the present application are as follows:

[0008] The method for evaluating and controlling the response of a shield to the superimposed disturbance of close proximity tunneling comprises:

[0009] S1, a multi-dimensional information database of stratum conditions in the docking area is constructed; the multi-dimensional information database comprises stratum parameters of the docking section, shield tunneling parameters, and spatiotemporal parameters of docking, and is used to extract mechanical behavior characteristics of the leading shield and mechanical behavior characteristics of the following shield;

[0010] S2, based on the multi-dimensional information database, the structural resistance of the leading shield is analyzed, and based on the additional load generated by the tunneling of the following shield and the initial stress field around the leading shield, the additional load borne by the leading shield is determined; the additional load borne by the leading shield comprises indirect conduction load between strata and instantaneous collision load;

[0011] S3, based on the structural resistance of the leading shield and the additional load borne by the leading shield, a response evaluation system of load and resistance ratio is established to determine the disturbance level, and according to the determination result of the disturbance level, micro-disturbance control measures are adopted; the micro-disturbance control measures comprise shield structure reinforcement, stratum reinforcement of the docking section, and control of the tunneling parameters of the following shield.

[0012] Further, the construction of the multi-dimensional information database of stratum conditions in the docking area comprises: based on geological exploration and permeability test, a permeability difference section is divided, and stratum parameters of the docking section are obtained; wherein the permeability difference section comprises sand layer and clay interbed; the stratum parameters of the docking section comprise permeability coefficient, porosity, elastic modulus and cohesion; the multi-dimensional information database is constructed by using the stratum parameters of the docking section in combination with shield tunneling parameters and spatiotemporal parameters of docking; the shield tunneling parameters comprise shield tunneling speed, cutterhead penetration, mud pressure and grouting amount; the spatiotemporal parameters of docking comprise distance between the two shields, docking time difference and shield attitude deviation; according to the multi-dimensional information database, the influence of the shutdown time difference on the additional stress field is analyzed, and a seepage-stress field dynamic coupling model is established by applying Darcy's law and Biot's consolidation theory to obtain the mechanical behavior characteristics of the leading shield and the mechanical behavior characteristics of the following shield.

[0013] Further, based on the multi-dimensional information database, the structural resistance of the leading shield is analyzed, and based on the additional load generated by the tunneling of the following shield and the initial stress field around the leading shield, the additional load borne by the leading shield is determined.

[0014] S21, based on the multi-dimensional information database, the influence of the shield shutdown time in different strata on the additional stress field is reproduced through numerical simulation to extract the shutdown state of the leading shield;

[0015] S22, according to the preceding shield shutdown state, the compressive capacity, the torsional capacity and the tensile capacity of the preceding shield are analyzed to obtain the evaluation result of the structural resistance of the preceding shield;

[0016] S23, the additional stress field when the following shield is tunneling is simulated, and the initial stress field around the preceding shield is combined to calculate the additional load on the preceding shield.

[0017] Further, based on the multi-dimensional information database, the influence of the shield shutdown time in different strata on the additional stress field is reproduced through numerical simulation to extract the preceding shield shutdown state, including:

[0018] S211, according to the geological condition parameters and the shield tunneling parameters in the multi-dimensional information database, a three-dimensional finite element model is established to simulate the sand layer, the clay layer and the tunnel structure under the preceding shield shutdown state; the range of the three-dimensional finite element model is set according to the shield diameter to meet the Saint-Venant principle;

[0019] S212, based on the geological condition parameters of the butt joint section, the material constitutive model of the sand layer and the clay layer is set, and the boundary conditions are set;

[0020] S213, by simulating the groundwater seepage, the pore water pressure calculated by the seepage field is coupled to the stress field as a body force to update the effective stress, and the seepage-stress equation is obtained by coupling;

[0021] S214, using the seepage-stress equation, the excess pore water pressure dissipation and stress relaxation of the preceding shield under different shutdown times are simulated, and the additional stress of the nodes around the preceding shield is extracted.

[0022] Further, according to the preceding shield shutdown state, the compressive capacity, the torsional capacity and the tensile capacity of the preceding shield are analyzed to obtain the evaluation result of the structural resistance of the preceding shield, including:

[0023] S221, the compressive capacity of the preceding shield is obtained by superimposing the frictional resistance between the soil and the shield shell and the total bearing capacity of the shield tail stop steel plate weld; the frictional resistance between the soil and the shield shell increases with the increase of the shutdown time;

[0024] S222, the sum of the torsional frictional resistance of the soil to the shield, the shear couple of the shield tail stop bolt and the shear couple of the segment bolt is calculated to obtain the torsional capacity of the preceding shield; the torsional capacity is used to resist the torque transmitted to the shield tail when the rotating cutter head of the following shield collides with the cutter head of the preceding shield;

[0025] S223, the stratum frictional resistance and the tensile bearing capacity of the segment bolt are combined to determine the tensile capacity of the preceding shield, and the evaluation result of the structural resistance of the preceding shield is obtained in combination with the compressive capacity and the torsional capacity of the preceding shield.

[0026] Further, the additional stress field when the following shield is excavated is simulated, and the initial stress field around the preceding shield is combined to calculate the additional load borne by the preceding shield, including:

[0027] S231, by establishing a field coupling model, simulating the space-time distribution of the additional stress field when the following shield is excavated, and extracting the evolution law of the additional stress field of the following shield;

[0028] S232, combining the initial stress field around the preceding shield with the additional stress field of the following shield, calculating the indirect conduction load and the instantaneous impact load of the stratum on the surface of the preceding shield, to obtain the additional load borne by the preceding shield;

[0029] Further, the additional stress field when the following shield is excavated is simulated, and the initial stress field around the preceding shield is combined to calculate the additional load borne by the preceding shield, including:

[0030] S2311, based on the multi-dimensional information database embedded dynamic parameters, a field coupling model coupling seepage, stress, displacement and matter is established; wherein the dynamic parameters include stratum permeability coefficient, mud viscosity and cutterhead penetration resistance, and the cutterhead penetration resistance is equal to the excavation contact force minus the static contact force;

[0031] S2312, according to the field coupling model, the mud seepage path is simulated by the fluid-solid coupling equation, and the stress field propagation range is analyzed by the Saint-Venant principle;

[0032] S2313, the space-time distribution of the additional stress field when the following shield is excavated is simulated by the finite element method, and the stress gradient difference between the sand layer and the clay layer is quantified.

[0033] Further, the space-time distribution of the additional stress field when the following shield is excavated is simulated by the finite element method, and the stress gradient difference between the sand layer and the clay layer is quantified, including: a three-dimensional dynamic finite element model of the following shield tunnel structure and stratum is established; the model range of the three-dimensional dynamic finite element model conforms to the Saint-Venant principle, so as to ensure that the boundary does not affect the stress field distribution; the unit dynamic activation technology is used to simulate the tunnel excavation construction process, and every time a ring is pushed forward, a ring of lining is activated and a ring of soil is removed; the cutterhead face support pressure and the shield tail grouting pressure are gradually applied as the moving face load; the full-field stress data is output according to the preset time interval, and the stress state of the key time point is recorded, and the three-dimensional stress nephogram at different times is drawn; the stress gradient difference between the sand layer and the clay layer is quantified by the maximum stress gradient.

[0034] Further, the additional stress field when the following shield is excavated is simulated, and the initial stress field around the preceding shield is combined to calculate the additional load borne by the preceding shield, including:

[0035] S2321, extract the stress field generated by the subsequent shield tunneling, combine the initial stress field around the preceding shield, and use the node force difference method to calculate the indirect conduction load of the stratum on the surface of the preceding shield;

[0036] S2322, a three-dimensional model of the two cutters and the surrounding soil is established, the cutter contact area is meshed, the contact type between the cutters is defined, the explicit dynamic solver is used for transient analysis, and the contact force time history curve is output to extract the instantaneous collision load; the instantaneous collision load includes the maximum load value, the collision torque and the action time.

[0037] Further, according to the structural resistance of the preceding shield and the additional load borne by the preceding shield, a response evaluation system of load and resistance ratio is established to determine the disturbance level, including: comparing the structural resistance of the preceding shield with the additional load borne by the preceding shield to establish a response evaluation system of load and resistance ratio; according to the comparison result of the response evaluation system of load and resistance ratio, the disturbance level is divided into light disturbance, moderate disturbance and heavy disturbance; when the disturbance level is light disturbance, automatic monitoring is triggered; when the disturbance level is moderate disturbance, the tunneling parameters of the subsequent shield are optimized; when the disturbance level is heavy disturbance, micro-disturbance control measures are taken.

[0038] The beneficial effects of the present application are:

[0039] (1) The present application constructs a multi-dimensional information database of the stratum conditions in the docking area, including the stratum parameters of the docking section, the shield tunneling parameters and the docking space-time parameters, first proposes a double shield cooperative mechanical behavior analysis method, combines a seepage-stress field dynamic coupling model, realizes accurate simulation and analysis of the additional stress field generated by the preceding shield under different stratum conditions and the subsequent shield tunneling, and provides a scientific basis for calculation of the additional load borne by the preceding shield.

[0040] (2) The present application innovatively proposes a double-mode phased load calculation method of indirect conduction load and instantaneous collision load of the stratum, simulates the space-time distribution of the additional stress field during the subsequent shield tunneling through the field coupling model, calculates the indirect conduction load of the stratum on the surface of the preceding shield through the node force difference method, and analyzes the instantaneous collision load through the three-dimensional dynamic model, breaks through the limitations of traditional static load analysis, and realizes comprehensive quantification of the additional load borne by the preceding shield under various stratum conditions.

[0041] (3) The application establishes a response evaluation system based on load-resistance ratio, scientifically divides the light disturbance, moderate disturbance and heavy disturbance levels by comparing the resistance of the preceding shield structure and the additional load, and triggers the corresponding control measures according to different disturbance levels, forming a three-in-one micro-disturbance control technology system of'strengthening the preceding shield structure, reinforcing the stratum of the docking section and controlling the excavation parameters of the following shield', which effectively solves the disturbance problem caused by the close excavation of shield docking in various strata, especially in the complex geological conditions of strong water permeable stratum and the like.

[0042] (4) The application comprehensively applies advanced technologies such as numerical simulation, fluid-solid coupling analysis and dynamic response evaluation, is suitable for shield docking engineering in different permeability difference sections (such as sand layer and clay layer), and realizes the micro-disturbance accurate docking (displacement ≤ ± 10mm) by accurately controlling the dynamic parameters such as shutdown time difference, permeability coefficient and mud viscosity, greatly improves the safety and economy of the close excavation of shield docking, and provides a systematic technical solution for major projects such as the three-channel tunnel. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0044] Figure 1 is a schematic diagram of the core steps of the shield close excavation superimposed disturbance response evaluation and control method according to the embodiment of the application;

[0045] Figure 2 is a schematic diagram of the hierarchical response mechanism in the shield close excavation superimposed disturbance response evaluation and control method according to the embodiment of the application;

[0046] Figure 3 is a specific implementation diagram of the shield tail stop technology in the shield close excavation superimposed disturbance response evaluation and control method according to the embodiment of the application;

[0047] Figure 4 is a control flowchart of the control of the excavation parameters of the following shield in the shield close excavation superimposed disturbance response evaluation and control method according to the embodiment of the application;

[0048] Figure 5 is a specific flowchart of the shield close excavation superimposed disturbance response evaluation and control method according to the embodiment of the application. DETAILED DESCRIPTION

[0049] To further illustrate the embodiments, the present application provides accompanying drawings which are part of the disclosure of the present application, mainly used to illustrate the embodiments, and can be used to explain the operating principle of the embodiments in conjunction with the related description of the specification. Those skilled in the art should be able to understand other possible implementations 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 generally used to represent similar components.

[0050] According to an embodiment of the present application, a shield close proximity tunneling superimposed disturbance response evaluation and control method is provided.

[0051] The present application will be further described in conjunction with the accompanying drawings and specific embodiments, as Figure 1 and Figure 5 shown, according to an embodiment of the present application, a shield close proximity tunneling superimposed disturbance response evaluation and control method is provided, which includes:

[0052] S1, constructing a multi-dimensional information database of stratum conditions in the docking area; the multi-dimensional information database includes stratum parameters of the docking section, tunneling parameters of the shield, and space-time parameters during docking, for extracting mechanical behavior characteristics of the preceding shield and mechanical behavior characteristics of the following shield;

[0053] S2, based on the multi-dimensional information database, analyzing the structural resistance of the preceding shield, and determining the additional load on the preceding shield according to the additional load generated by the tunneling of the following shield and the initial stress field around the preceding shield; the additional load on the preceding shield includes indirect conduction load between strata and instantaneous collision load;

[0054] S3, establishing a response evaluation system of load and resistance ratio based on the structural resistance of the preceding shield and the additional load on the preceding shield to determine the disturbance level, and using micro-disturbance control measures according to the disturbance level determination result; the micro-disturbance control measures include shield structure reinforcement, stratum reinforcement in the docking section, and tunneling parameter control of the following shield.

[0055] Specifically, as Figure 1 shown, the present application includes 6 steps. Specifically, it includes: step 1, determination of stratum conditions in the docking area; step 2, extraction of the preceding shield shutdown state; step 3, evaluation of the structural resistance of the preceding shield; step 4, analysis of additional load during docking tunneling; step 5, response evaluation; step 6: trinity micro-disturbance control.

[0056] Specifically, in step 1, the present application extracts mechanical behavior characteristics. The present application proposes a method for studying the mechanical behavior of the preceding and following shields, including the geological conditions of the docking section, the tunneling state and parameters of the preceding and following shields, and the docking time difference between the preceding and following shields, to determine the mechanical behavior characteristics of the preceding and following shields.

[0057] Specifically, in step 2, the present application carries out additional stress field evolution law extraction. The present application establishes an additional stress field evolution law research model and analysis method based on fluid-solid coupling analysis to master the additional stress field evolution law of shield docking. In step 2, the preceding shield is not considered, and only the additional stress field evolution law generated by the following shield during tunneling is considered. The additional stress at different times and positions is not the same.

[0058] Specifically, in steps 3 and 4, the present application carries out preceding shield structure resistance evaluation and additional load extraction. The present application establishes a time-space distribution pattern and calculation method of the disturbed additional load of the preceding shield, obtains the indirect additional load conducted from the stratum to the preceding shield from far to near, and the instantaneous dynamic disturbance load at the moment of collision between the preceding and following shields. In this analysis process, the preceding shield begins to bear the additional stress of step 2. The present application obtains the additional stress of each point by comparing the stress difference of each position of the preceding position with the original ground stress at a certain time. Finally, the two cutters will collide to generate collision load extrusion or torsion.

[0059] Specifically, in step 5, the present application carries out response evaluation. By establishing a preceding and following shield response evaluation model, the response degree of the preceding and following shields is evaluated

[0060] Specifically, in step 6, the present application carries out micro-disturbance control. The micro-disturbance quantitative control technology developed by the present application includes preceding shield structure reinforcement (pipe piece tie, shield tail stop needle targeted design, main drive stop needle targeted design, etc.), stratum reinforcement (tunnel radial grouting, shield body radial grouting, hole outside super strong curtain grouting, etc.), following shield tunneling parameter control (supporting pressure, tunneling speed, attitude control, mud index, cutter speed, etc.), to realize micro-disturbance precise docking.

[0061] In one embodiment, constructing a multi-dimensional information database of stratum conditions in a docking area includes: dividing a permeability difference section based on geological exploration and permeability test, and obtaining stratum parameters of a docking section; wherein the permeability difference section includes a sand layer and a clay interbed; the stratum parameters of the docking section include a permeability coefficient, a porosity, an elastic modulus, and a cohesion; using the stratum parameters of the docking section, combining shield tunneling parameters and docking space-time parameters, a multi-dimensional information database is constructed; the shield tunneling parameters include a shield tunneling speed, a cutter penetration degree, a mud pressure, and a grouting amount; the docking space-time parameters include a distance between two shields, a docking time difference, and a shield attitude deviation; according to the multi-dimensional information database, the influence of the shutdown time difference on the additional stress field is analyzed, and a seepage-stress field dynamic coupling model is established by applying Darcy's law and Biot's consolidation theory, to obtain mechanical behavior characteristics of the preceding shield and mechanical behavior characteristics of the following shield.

[0062] It should be noted that the research object of the present application includes two typical strata: homogeneous sand layer and non-homogeneous clay-sand interbedded layer (clay interbedded layer), and the clay interbedded layer in step 1 represents the macroscopic stratum classification. When micro material analysis is carried out in step 2, the present application uses "clay layer" to establish a numerical model, and the clay material part in the "clay interbedded layer" is abstracted and defined as a material unit of "clay layer" to carry out mechanical calculation.

[0063] Specifically, the present application realizes the determination of the stratum conditions of the docking area in step 1, including:

[0064] 1) Using geological exploration and permeability test, the stratum parameters (permeability coefficient, porosity, elastic modulus, cohesion, etc.) of the docking section are obtained, and the sand layer, clay interbedded layer and other permeability difference sections are divided.

[0065] 2) A three-dimensional information database (multi-dimensional information database) containing 30 parameters is constructed to realize the multi-dimensional correlation of geological conditions, construction parameters and docking time difference. The parameters include: stratum permeability coefficient (k), porosity (n), elastic modulus (E), cohesion (c), internal friction angle (φ), soil density (ρ), consolidation coefficient (cv), initial pore water pressure (u0), excess pore water pressure dissipation rate, stratum type (sand layer / clay / interbedded layer), permeability path length (L), pore water pressure gradient (u), shield diameter (D), shield tunneling speed (V), cutterhead penetration (P), cutterhead rotation speed (N), mud pressure (Pm), mud viscosity (μ), mud specific gravity (γ), shield tail grouting pressure (Pp), grouting amount (Qp), support pressure (Qs), shield downtime (t), static contact force (Fst), tunneling contact force (Ft), distance between two shields (r), docking time difference (Δt), shield attitude horizontal deviation (Δx), shield attitude vertical deviation (Δy), shield attitude angle deviation (Δθ). 泥浆 注浆 注浆 支护 停机 静 掘

[0066] Specifically, the extraction of the mechanical behavior characteristics of the leading and trailing shields in the present application includes:

[0067] 1) Stratum permeability zoning: according to geological exploration and permeability test, the sand layer, clay interbedded layer and other permeability difference sections are divided, and the key parameters such as permeability coefficient (k), porosity (n), elastic modulus (E), cohesion (c) of different strata are determined.

[0068] 2) Multi-dimensional information database construction:

[0069] ​​​​​​​​​Stratum parameters of the docking section: permeability coefficient, initial pore water pressure (u0), consolidation coefficient (cv), soil density (p);

[0070] Shield tunneling parameters: shield tunneling speed (V), cutterhead penetration (P), mud pressure (Pmud), grouting amount (Q 注浆 );

[0071] Space-time parameters during docking: distance between two shields (r), docking time difference (At), shield attitude deviation (Ax / Dy / Dq).

[0072] 3) Influence of shutdown time difference on additional stress field: through numerical simulation, the dissipation of excess pore water pressure and stress relaxation under different shutdown times are simulated.

[0073] 4) Application of Darcy's law and Biot's consolidation theory to establish dynamic coupling of seepage-stress field.

[0074] Specifically, among the 30 parameters selected by the present application, the establishment of the stratum parameters of the docking section is for the surrounding environmental conditions and the initial stress field of the shield; and the establishment of the shield tunneling parameters is for the mechanical behavior analysis during the docking of the two shields.

[0075] In one embodiment, based on the multi-dimensional information database, the resistance of the leading shield structure is analyzed, and based on the additional load generated by the tunneling of the trailing shield and the initial stress field around the leading shield, the additional load borne by the leading shield is determined, including:

[0076] S21, based on the multi-dimensional information database, the influence of the shield shutdown time in different strata on the additional stress field is reproduced through numerical simulation to extract the shutdown state of the leading shield;

[0077] S22, according to the shutdown state of the leading shield, the evaluation result of the structural resistance of the leading shield is obtained by analyzing the compression resistance, torsion resistance and tensile resistance of the leading shield;

[0078] S23, by simulating the additional stress field during the tunneling of the trailing shield, the additional load borne by the leading shield is calculated in combination with the initial stress field around the leading shield.

[0079] In one embodiment, based on the multi-dimensional information database, the influence of the shield shutdown time in different strata on the additional stress field is reproduced through numerical simulation to extract the shutdown state of the leading shield, including:

[0080] S211, according to the stratum geological condition parameters and shield tunneling parameters in the multi-dimensional information database, a three-dimensional finite element model is established to simulate the tunnel structure under the conditions of sand layer, clay layer and leading shield shutdown; the range of the three-dimensional finite element model is set according to the diameter of the shield to meet the Saint-Venant principle;

[0081] S212, based on the geological condition parameters of the joint section, set the material constitutive model of the sand layer and the clay layer, and set the boundary conditions;

[0082] S213, by simulating the seepage of underground water, the pore water pressure calculated by the seepage field is coupled to the stress field as a volume force to update the effective stress, and the seepage-stress equation is obtained by coupling;

[0083] S214, using the seepage-stress equation, simulating the dissipation of excess pore water pressure and stress relaxation of the preceding shield under different downtime, and extracting the additional stress of the nodes around the preceding shield.

[0084] In one embodiment, setting the boundary conditions includes: fixing the vertical displacement of the bottom of the model, and applying the normal constraint; according to the actual hydrological conditions around the model, setting the free drainage boundary, impermeable boundary or constant water head; generating the initial stress field around the preceding shield by gravity loading, and distributing the pore water pressure according to the hydrostatic pressure.

[0085] Specifically, the preceding shield downtime state extraction is realized in step 2, and the influence of shield downtime on the additional stress field in different strata is reproduced by numerical simulation. It includes:

[0086] 1) model establishment and parameter setting, specifically including:

[0087] Model establishment:

[0088] ① Establish a three-dimensional finite element model to simulate (sand layer, clay layer) and static preceding shield (preceding shield downtime state) tunnel structure.

[0089] ② The model range should cover at least 3 times the lateral and longitudinal area of the shield diameter to meet the Saint-Venant principle and ensure that the boundary does not affect the stress field distribution.

[0090] ③ The preceding shield is set to be in a static state, and only the interaction between stratum seepage and stress field is considered.

[0091] Set the material constitutive model:

[0092] ① The sand layer adopts Mohr-Coulomb model, and the permeability coefficient (k), elastic modulus (E), internal friction angle ( ), and cohesion (c) are input. The clay layer adopts the modified Cambridge (Cam-Clay) model, considering the consolidation coefficient (c v ) and the dissipation characteristics of excess pore water pressure.

[0093] ② The shield structure adopts elastic shell element, the elastic modulus of steel (E=210GPa), and the Poisson's ratio (ν=0.3). The friction coefficient (μ=0.2~0.4) is set on the contact surface between the shield body and the soil.

[0094] Set boundary conditions:

[0095] ① The bottom of the three-dimensional finite element model is fixed vertically (U z =0), and the four sides are applied with normal constraints (U x =0 or U y =0).

[0096] ② According to the actual hydrological conditions around the three-dimensional finite element model, set free drainage boundary, impermeable boundary or constant water head (zero flow).

[0097] ③ Generate initial stress field by gravity loading, and pore water pressure is distributed according to hydrostatic pressure.

[0098] 2) Fluid-structure coupling analysis settings, including:

[0099] ① Apply Darcy's law to simulate groundwater seepage, calculate seepage velocity by the following equation, and the expression for simulating groundwater seepage is:

[0100] ;

[0101] In the formula, q is the seepage velocity (m / s); k is the permeability coefficient of the medium (m 2 ); μ is the dynamic viscosity of the fluid (Pa·s); p is the pressure gradient (Pa / m); ρ l is the fluid density (kg / m 3 ); g is the acceleration of gravity (m / s 2 ).

[0102] ② The pore water pressure calculated by the seepage field is coupled to the stress field as a body force, and the effective stress is updated, and the expression is:

[0103] σ'=σ-u;

[0104] In the formula, σ' is the effective stress (Pa), which determines the deformation and strength of the soil; σ is the total stress (Pa), which is generated by external load and self weight of the soil; u is the pore water pressure (Pa), which includes hydrostatic pressure and excess pore water pressure.

[0105] ③ Use Biot's consolidation theory to couple the seepage-stress equation, and the expression is:

[0106] ·(σ')+ρ t g=0;

[0107] In the formula, ·(σ') is the additional stress; ρ t is the density of the soil (kg / m 3 ); g is the acceleration of gravity (m / s2 ).

[0108] 3) Working condition and loading design, specifically including:

[0109] ① Set up sand layer and clay layer for simulating working conditions.

[0110] ② Calculate initial ground stress and pore water pressure.

[0111] ③ Keep the shield structure fixed, simulate the dissipation of excess pore water pressure and stress relaxation under different downtime.

[0112] ④ Output stress field data every hour.

[0113] 4) Result extraction and analysis, specifically including:

[0114] ① Extract the additional stress of the nodes around the preceding shield, and output the space-time distribution cloud chart;

[0115] ② Compare the stress concentration areas in the sand layer and the clay layer;

[0116] ③ Draw the curve of excess pore water pressure changing with time, and evaluate the consolidation rate.

[0117] Specifically, define the time difference level: short time difference (sand layer ≤ 3 days, clay ≤ 30 days), medium time difference (sand layer 3-7 days, clay 1-6 months), long time difference (sand layer > 7 days, clay > 6 months).

[0118] In one embodiment, according to the downtime state of the preceding shield, the evaluation result of the structural resistance of the preceding shield is obtained by analyzing the compression resistance, torsion resistance and tensile resistance of the preceding shield, including:

[0119] S221, the compression resistance of the preceding shield is obtained by superimposing the friction resistance between the soil and the shield shell and the total bearing capacity of the shield tail stop steel plate weld; the friction resistance between the soil and the shield shell increases with the increase of downtime;

[0120] S222, the sum of the torsional friction resistance of the soil to the shield, the shear couple of the shield tail stop bolt and the shear couple of the segment bolt is calculated to obtain the torsion resistance of the preceding shield; the torsion resistance is used to resist the torque transmitted to the shield tail when the cutter head of the following shield collides with the cutter head of the preceding shield;

[0121] S223, the tensile resistance of the preceding shield is determined by combining the ground friction resistance and the tensile bearing capacity of the segment bolt, and the evaluation result of the structural resistance of the preceding shield is obtained in combination with the compression resistance and the torsion resistance of the preceding shield.

[0122] Specifically, the structural resistance evaluation of the preceding shield is realized in step 3, including:

[0123] In the process of shield butt joint, the carrying disturbance ability (structural resistance) of the leading shield needs to be comprehensively evaluated from the aspects of compression resistance, torsion resistance and longitudinal tension resistance. The longitudinal force of the soil mass in front of the leading shield is transmitted to the shield tail through the friction of the soil mass, and the longitudinal force at the shield tail is borne by the weld of the tail stop plate. Therefore, the compression resistance is mainly ensured by the cooperation of the stratum friction and the tail stop device. The total compression resistance is obtained by superimposing the friction resistance between the soil mass and the shield shell and the total bearing capacity of the weld of the tail stop plate. Compared with the friction resistance between the soil mass and the shield shell in a short time, the friction resistance between the soil mass and the shield shell after a long time is greater.

[0124] F=F1+F2;

[0125] In the formula, F is the compression resistance of the leading shield; F1 is the friction resistance between the soil mass and the shield shell; and F2 is the total bearing capacity of the weld of the tail stop plate.

[0126] In the process of shield butt joint, the cutter head of the trailing shield will collide with the cutter head of the leading shield, and part of the torque is transmitted to the shield tail through the leading shield cutter head-main drive-shield shell. The torsion resistance is composed of the soil wrapping effect and the shear couple of the tail stop bolt and segment bolt.

[0127] T=T1+T2+T3;

[0128] In the formula, T is the torsion resistance of the leading shield, T1 is the torsion friction resistance of the soil mass to the shield, T2 is the shear couple of the tail stop bolt, and T3 is the shear couple of the segment bolt.

[0129] The tensile resistance of the leading shield is composed of the stratum friction and the tensile bearing capacity of the segment bolt.

[0130] L=L1+L2;

[0131] In the formula, L is the tensile resistance of the leading shield, L1 is the stratum friction, and L2 is the tensile bearing capacity of the segment bolt.

[0132] In one embodiment, the additional load borne by the leading shield is calculated by simulating the additional stress field when the trailing shield is tunneling, combined with the initial stress field around the leading shield, including:

[0133] S231, by establishing a field coupling model, simulating the space-time distribution of the additional stress field when the trailing shield is tunneling, and extracting the evolution law of the trailing additional stress field;

[0134] S232, combined with the initial stress field around the leading shield and the trailing additional stress field, the indirect conduction load and the instantaneous collision load of the stratum on the surface of the leading shield are calculated to obtain the additional load borne by the leading shield;

[0135] Wherein, by establishing a field coupling model, the time and space distribution of the additional stress field when the rear shield is excavated is simulated, and the evolution law of the rear additional stress field is extracted, including:

[0136] S2311, based on the multi-dimensional information database, the dynamic parameters are embedded to establish a field coupling model coupling seepage, stress, displacement and material; wherein, the dynamic parameters include formation permeability coefficient, mud viscosity and cutterhead penetration resistance, and the cutterhead penetration resistance is equal to the excavation contact force minus the static contact force;

[0137] S2312, according to the field coupling model, the mud seepage path is simulated by the fluid-solid coupling equation, and the stress field propagation range is analyzed combined with the Saint-Venant principle;

[0138] S2313, the finite element method is used to simulate the time and space distribution of the additional stress field when the rear shield is excavated, and the stress gradient difference between the sand layer and the clay layer is quantified.

[0139] In one embodiment, the finite element method is used to simulate the time and space distribution of the additional stress field when the rear shield is excavated, and the stress gradient difference between the sand layer and the clay layer is quantified, including:

[0140] A three-dimensional dynamic finite element model of the rear shield tunnel structure and the stratum is established; the model range of the three-dimensional dynamic finite element model conforms to the Saint-Venant principle to ensure that the boundary does not affect the stress field distribution;

[0141] The unit dynamic activation technology is used to simulate the tunnel excavation construction process, and every time a ring is pushed forward, a ring of lining is activated and a ring of soil is removed; the cutterhead face support pressure and the shield tail grouting pressure are gradually applied as moving surface load;

[0142] The full-field stress data is output according to the preset time interval, and the stress state of the key time points is recorded, and the three-dimensional stress nephogram at different times is drawn;

[0143] The stress gradient difference between the sand layer and the clay layer is quantified by the maximum stress gradient.

[0144] In one embodiment, the indirect conduction load and the instantaneous impact load of the stratum on the surface of the preceding shield are calculated combined with the initial stress field around the preceding shield and the additional stress field of the rear shield to obtain the additional load on the preceding shield, including:

[0145] S2321, the stress field generated by the rear shield excavation is extracted, and the indirect conduction load of the stratum on the surface of the preceding shield is calculated by the node force difference method combined with the initial stress field around the preceding shield;

[0146] S2322, a three-dimensional model of two cutters and the surrounding soil is established, the cutter contact area is meshed, the contact type between the cutters is defined, the explicit dynamics solver is used for transient analysis, and the contact force time history curve is output to extract the instantaneous collision load; the instantaneous collision load includes the maximum load value, the collision torque and the action time.

[0147] Specifically, the application realizes additional load analysis of butt joint tunneling in step 4, including:

[0148] Step 4.1, the extraction of the evolution law of the rear additional stress field:

[0149] Specifically, a field coupling model (four-field coupling model of "seepage-stress-displacement-matter") is established, and dynamic parameters such as stratum permeability coefficient, mud viscosity and cutter penetration resistance (cutter penetration resistance = tunneling contact force - static contact force, which are parameters of the rear shield machine and have been supplemented in the step 1 database) are embedded.

[0150] Specifically, the four-field coupling model of "seepage-stress-displacement-matter" includes: seepage field: simulate the seepage path and pore water pressure distribution of mud and groundwater based on Darcy's law (simulate the seepage path of mud through fluid-solid coupling equation); stress field: simulate the change of effective stress based on Biot's consolidation theory (step 2 uses Biot's consolidation theory to couple seepage-stress equation), and the pore water pressure calculated by the seepage field is coupled to the stress field as a body force; displacement field: solve the displacement response of stratum and structure caused by stress field change through finite element method; material field: dynamically simulate the tunneling process through element birth and death technology (activate a ring lining element and remove a ring soil element every time a ring is advanced), and apply the cutter face support pressure and shield tail grouting pressure as a moving surface load to reflect the dynamic change of the tunneling material.

[0151] Specifically, the seepage field, stress field and displacement field correspond to the classical geotechnical engineering numerical simulation physical field. In the application, the relatively vague expression of material field is specifically explained as the dynamic change process of "tunneling material (soil and lining)" simulated by "element birth and death technology" and "moving load".

[0152] Specifically, the mud seepage path is simulated by fluid-solid coupling equation (Darcy's law) (combine with the database in step 1, simulate the actual engineering mud seepage path by Darcy's law, so as to better reflect the real additional stress field evolution law), and the stress field propagation range is analyzed by Saint-Venant principle (the influence can be ignored when > 3 times the diameter of the shield); it should be noted that the definition of Saint-Venant principle is: if the resultant force and the resultant moment of the load acting on a small area (or volume) of the elastic body are equal to zero, the stress is almost equal to zero far away from the load acting area. According to engineering experience, the stress in the range of 3 times the diameter of the shield is considered here, and the influence can be ignored when > 3 times the diameter of the shield.

[0153] ;

[0154] In the formula, q is the Darcy flow rate (unit: m / s); k is the medium permeability (unit: m 2 ); μ is the dynamic viscosity of fluid (unit: Pa·s); p is the pressure gradient (unit: Pa / m); ρ l is the fluid density (unit: kg / m 3 ); g is the gravity acceleration vector (unit: m / s 2 ).

[0155] Specifically, the finite element method is used to simulate the time and space distribution of the additional stress field when the rear shield is excavated, and the stress gradient difference between the sand layer and the clay layer is quantified. Among them:

[0156] 1) three-dimensional dynamic finite element model construction, specifically including:

[0157] ①Establish a three-dimensional model of the rear shield tunnel structure and the stratum (sand layer, clay layer), and the model range should meet the Saint-Venant principle to ensure that the boundary does not affect the stress field distribution (when modeling, the boundary of the soil body is set to be greater than 3 times the diameter of the shield required by the Saint-Venant principle, because the simulation stress field result will not appear in the range outside 3 times the diameter of the shield. Therefore, we require the boundary to be set to 3 times the diameter of the shield required by the Saint-Venant principle).

[0158] ②The constitutive and parameters of the shield structure, sand layer and clay layer are the same as the parameter setting in step 1.

[0159] 2) simulate the tunnel excavation construction process, specifically including:

[0160] ①Use the element dynamic activation technology (numerical simulation software "birth and death element" technology), and every time a ring is pushed forward, a ring of lining is "born" and a ring of soil body is "died", and the pushing speed is valued according to the conventional value.

[0161] ②At the same time, the cutter head face support pressure and the shield tail grouting pressure are gradually applied as the moving face load.

[0162] 3) Spatiotemporal distribution data monitoring and extraction, specifically including:

[0163] ① Full-field stress data is output every 0.1 h of excavation, with key time points (cutterhead cutting in, stable excavation, shutdown) being recorded, and three-dimensional stress nephograms at different times being drawn.

[0164] 4) Quantification of stress gradient of sand layer and clay layer, specifically including:

[0165] The greater the maximum stress gradient value, the more significant the stress concentration, which directly determines the stratum instability risk level (sand layer > clay layer); the maximum principal stress change amount dominates sand layer shear failure (e.g., soil splitting in front of the cutterhead); the minimum principal stress change amount dominates clay layer compression deformation (e.g., shielded soil extrusion settlement); the radial distance differential determines the key variable of stress attenuation rate. max ensures that the quantification result covers the most unfavorable working condition. Through the maximum stress gradient, the expression for quantifying the difference in stress gradient of the sand layer and the clay layer is:

[0166] ;

[0167] In the formula, G max is the maximum stress gradient (Mpa / m), representing the extreme value of the principal stress change per unit distance in the stratum, reflecting the disturbance intensity; is the maximum principal stress change amount (Mpa), representing the maximum principal stress increment (tensile / compressive stress) caused by the excavation of the trailing shield; is the minimum principal stress change amount (Mpa), representing the minimum principal stress increment (constraint stress) caused by the excavation of the trailing shield; Δ r is the radial distance differential (m), representing the change amount of the radial distance from the calculation point to the center of the trailing shield cutterhead.

[0168] Step 4.2, extraction of additional load on the leading shield:

[0169] (1) For indirect conduction load calculation between strata, first extract the stress field generated by the excavation of the trailing shield in step 2, combine the initial stress field around the leading shield (obtained by reproducing the effect of different strata on the additional stress field through numerical simulation in the extraction of the leading shield shutdown state in step 2), and use the node force difference method to calculate the indirect load spatiotemporal distribution on the surface of the leading shield (indirect conduction load between strata), with the expression being:

[0170] ;

[0171] In the formula, q 间接 is the indirect additional load on the surface of the leading shield (indirect conduction load between strata); ∑q 后行(x, y, z) is the stress field (position x, y, z) generated by the step 2 rear shield tunneling; ∑q 先行初始 is the initial stress field around the preceding shield.

[0172] (2) For the instantaneous impact load, a three-dimensional model of the two cutters and the surrounding soil is established using finite element software, and the cutter contact area is finely meshed to ensure that stress concentration is captured. The cutter adopts an elastic-plastic material model, and the soil selects a Mohr-Coulomb or Drucker-Prager constitutive model, and sets damping parameters to simulate energy dissipation. The contact between the cutters is defined as "face-face contact" or "automatic contact", and the penalty function method or Lagrange multiplier method suitable for impact analysis is selected. The soil boundary uses spring-damping elements or infinite elements to simulate far-field effects, constrain the degrees of freedom of the shield machine tail, and simulate the fixed conditions in actual pushing. The explicit dynamic solver is used for transient analysis, a reasonable time step is set, the contact force time history curve is output, and the maximum load value, collision torque and action time are extracted.

[0173] In one embodiment, according to the preceding shield structure resistance and the additional load borne by the preceding shield, a load and resistance ratio response evaluation system is established to determine the disturbance level, including:

[0174] The preceding shield structure resistance is compared with the additional load borne by the preceding shield to establish a load and resistance ratio response evaluation system;

[0175] According to the comparison result of the load and resistance ratio response evaluation system, the disturbance level is divided into light disturbance, moderate disturbance and severe disturbance;

[0176] When the disturbance level is light disturbance, automatic monitoring is triggered; when the disturbance level is moderate disturbance, the rear shield tunneling parameters are optimized; and when the disturbance level is severe disturbance, micro-disturbance control measures are taken.

[0177] Specifically, the present application realizes response evaluation in step 5, including:

[0178] The indirect conduction load between strata in step 3, the instantaneous impact load and the load-bearing disturbance capacity (preceding shield structure resistance) of the preceding shield are compared. If the disturbance resistance is strong, no treatment is needed, and if the disturbance resistance is insufficient, micro-disturbance control measures need to be taken.

[0179] (1) A load and resistance ratio (λ) response evaluation system is established, and the expression is:

[0180] ;

[0181] In the formula, λ 压 , λ 扭 , λ 拉respectively, are pressure, torque, tension disturbance level; T 碰撞 is the peak value of collision torque; ∇q 间接 is the conduction load gradient (reflecting the longitudinal tension); q 间接 is the indirect additional load of the preceding shield surface (indirect conduction load of the stratum); F is the compressive capacity of the preceding shield; T is the torsional capacity of the preceding shield; L is the tensile capacity of the preceding shield.

[0182] (2) Disturbance level classification rules, based on λ value to determine the disturbance level, as shown in Table 1.

[0183] Table 1 Disturbance level classification rules

[0184]

[0185] (3) Dynamic feedback control trigger, as shown in Figure 2 , specifically including:

[0186] ① Mild / medium disturbance: trigger automatic monitoring, and automatically activate the tunneling parameter optimization module (adjust support pressure, tunneling speed, etc.) of step 6

[0187] ② Severe disturbance: trigger trinity micro-disturbance control technology (structure reinforcement + stratum reinforcement + tunneling parameter adjustment)

[0188] In one embodiment, the micro-disturbance control measures include shield structure reinforcement, abutment segment stratum reinforcement, and trailing shield tunneling parameter control, wherein:

[0189] Shield structure reinforcement includes segment tie-in technology, shield tail stop technology, and main drive stop technology, specifically including: determining the longitudinal segment reinforcement range of the shield tunnel and determining the length, width and thickness of the longitudinal reinforcement steel plate, welding and fixing the longitudinal reinforcement steel plate with the anchor steel plate, and using the whole ring reinforcement method to longitudinally reinforce the shield tunnel; install anchor plate and rubber protection layer on the assembled segment, and after the retracting jack, the welded steel plate is assembled in the corresponding position of the segment, the anchor bolt is installed and the sealing pad is compressed, and after the whole ring steel plate installation is completed, the steel plate is welded and fixed with the shield shell; determine the plane size and weld range of the stop steel plate, and based on the strength calculation results of the stop steel plate base material and weld, optimize the stop steel plate parameters.

[0190] The interface section stratum reinforcement includes tunnel radial grouting, shield body radial grouting and hole outside super strong curtain grouting, and specifically includes: using the trailing shield tail synchronous grouting system to carry out pressure control grouting, when the grouting pressure continuously rises to the set threshold, the grouting is paused and is at rest, and after the pressure dissipates, it is restarted; based on the flushing pipeline of the leading shield slurry tank, the reinforcing slurry is injected into the slurry tank in stages, and the lower initial filling, the middle pressure maintaining filling and the upper sealing filling are sequentially carried out; through the radial grouting hole and the advanced grouting hole preset on the shield shell, the shield body radial grouting and the shield outside advanced compensation grouting are sequentially carried out from bottom to top.

[0191] The trailing shield tunneling parameter control controls the tunneling speed, the penetration degree, the cutter head rotating speed and the support pressure of the working face by dynamically adjusting, so that the sum of the trailing penetration resistance and the trailing working face support pressure is not greater than the static earth pressure of the leading shield, and the additional stress generated by the trailing shield is minimized.

[0192] Specifically, the trinity micro-disturbance control is realized in step 6. The micro-disturbance control measures in the application include leading shield structure reinforcement (segment tie, shield tail stop needle design, main drive stop needle design, etc.), interface section stratum reinforcement (shield tail persistent pressure maintaining grouting, leading shield slurry tank staged pressure control filling reinforcement, shield body radial and advanced compensation grouting, etc.), trailing shield tunneling parameter control (support pressure, tunneling speed, attitude control, mud index, cutter head rotating speed, etc.), to realize micro-disturbance precise docking, including:

[0193] (1) Shield structure reinforcement technology, specifically including:

[0194] 1) Segment tie technology: ① Determine the longitudinal segment reinforcement range of the shield tunnel, and then determine the length L (m) of the longitudinal reinforcement steel plate; ② Determine the size of the longitudinal reinforcement steel plate, where the size specifically refers to the width a (mm) and the thickness b (mm); ③ Weld and fix the longitudinal reinforcement steel plate and the anchor steel plate. ④ The arrangement position of the longitudinal reinforcement steel plate and the anchor steel plate of the shield tunnel structure needs to match the inter-ring longitudinal bolt, so that the overall connectivity is good, and the common stress of the longitudinal reinforcement steel plate and the bolt is good, so that the strength of the two can be fully utilized. ⑤ The longitudinal reinforcement of the shield tunnel adopts the whole ring reinforcement mode, so that the rigidity of the whole ring section is uniformly distributed, and then the tunnel structure is uniformly stressed on the ring section. This ensures that the leading shield segment structure has stronger resistance.

[0195] 2) Shield tail stop technology: ① Drill and install anchor plates and neoprene protective layers on the assembled segments. ② After completing the manufacturing of each component of the water stop device in the factory, transport it to the site, retract a group of jacks, and integrally assemble the welded steel plate 1, steel plate 2 and steel round pressure strip at the corresponding position of the segment, such as Figure 3Figure 3 is a sectional view of a shield tail water stop device using the shield tail water stop technology of the present application. 3. Drill holes in the segment to install anchor bolts, and tighten the bolts while pressing the gaskets. During the installation of the anchor bolts, ensure that all the anchor bolts are synchronously and uniformly stressed. 4. Install the steel plate 3 Figure 3 The steel plate 3 is divided into two types and arranged alternately. The first type of steel plate 3 is installed synchronously when the jacks are removed, and the second type of steel plate 3 is installed before the freezing construction. 5. Repeat the procedures 2-4 to complete the installation of the steel plate 1, the steel plate 2, and the steel plate 3 of the whole ring. After the settlement is stabilized, the steel plate 2 is firmly welded to the shield shell, and the anchor plate is welded to the steel plate 2 using the connecting steel plate. After the welding is completed, drill holes to fill the gap between the shield tail and the gap between the steel plate 1 and the segment concrete with grouting. After the filling is completed, check the sealing property of the water stop device by water pressure.

[0196] 3) Main drive stop technology: The present application determines the plane size of the stop steel plate by analyzing the space position of the main drive. The reasonable range of the weld is determined by considering the sealing of the main drive. The design basis for the main drive stop reinforcement is determined by determining the retraction force of the main drive telescopic oil cylinder. The parameters of the stop steel plate are reasonably optimized by strength calculation of the stop steel plate base material and weld, ensuring the risk of main drive retraction during shield butt joint.

[0197] (2) Butt joint section stratum reinforcement technology, specifically including:

[0198] 1) Shield tail persistent pressure maintenance grouting: When approaching the butt joint area during tunneling, the shield tail synchronous grouting system of the trailing shield is used to perform persistent and intermittent pressure control grouting with good stability and low shrinkage grout. By monitoring the grouting pressure and flow in real time, the grouting strategy is dynamically adjusted. When the grouting pressure continuously rises to the set threshold, the grouting is stopped and the pressure is dissipated, and then restarted to ensure that the grout fully fills the shield tail gap and continuously penetrates into the surrounding soil, forming a uniform and dense reinforcement ring.

[0199] 2) Pre-arranged mud chamber pressure control filling and reinforcement: After the pre-arranged shield machine stops, the upper, middle and lower flushing pipes in the mud chamber are used to fill and reinforce the slurry in the chamber in stages, to replace the original slurry and solidify the chamber, form a rigid support to prevent the shield machine head from deforming under its own weight, seal the front ground to eliminate the risk of water and sand gushing, and actively reinforce the front and surrounding soil. The specific steps include: a) initial filling of the lower part: first, low-strength mortar is injected into the mud chamber through the lower flushing pipe to initially fill the lower part of the mud chamber, and the filling height should be higher than the lower edge of the front chamber door by a certain height to ensure effective sealing of the lower part of the chamber door. b) middle pressure maintenance filling: after the initial filling of the slurry reaches a certain strength, low-strength mortar is continuously injected through the middle flushing pipe; at the same time, overflow slurry is discharged through the upper pipe, and the mud chamber pressure is monitored and controlled in real time to maintain it at a preset target value slightly higher than the static water and soil pressure of the ground, to prevent the face from losing stability; when the overflow pipe flows out of the mortar, the overflow valve is closed, and the grouting continues until the grouting pressure reaches the preset upper limit, and then stops. c) final sealing filling of the upper part: after the middle filling slurry reaches a certain strength, cement slurry is injected through the upper flushing pipe until the mud chamber is completely filled and reaches the predetermined sealing and reinforcement strength.

[0200] 3) Shield body radial and advanced compensation grouting: The prearranged radial and advanced grouting holes on the shield shell are used to accurately compensate and grout the voids around the shield body caused by construction disturbance, to seal the shield body, fill the voids and stabilize the surrounding ground. The specific steps include: a) shield body radial grouting: first, open and clear the radial grouting hole valve at the front of the shield body, connect the grouting pipe, use a single liquid slurry system, and grout in the order from bottom to top; monitor the grouting pressure in real time during the grouting process, and stop the grouting when the pressure continuously reaches the preset termination pressure value, to ensure that the slurry spreads fully without splitting the ground. b) shield external advanced compensation grouting: then, open and clear the advanced grouting hole valve, use high-pressure medium to pre-clear the grouting pipe, and after confirming that the pipe is unobstructed, connect the grouting system for pressure grouting, which follows the same order and pressure control principles as step a, to further reinforce and seal the soil outside the radial grouting range. c) grouting effect verification and closed-loop control: after all grouting operations are completed and the slurry reaches a certain strength, sample drilling is performed on the grouting holes; the sealing and integrity of the grouting body are quantitatively evaluated by checking whether there is any leakage of water in the drilling; if leakage is found, supplementary grouting of the corresponding area is immediately started, and effect verification is performed again to form a closed-loop quality control process of "grouting-detection-reinforcement", until the area is completely sealed.

[0201] (3) The control of the tunneling parameters of the following shield: The tunneling speed and the penetration depth are the core dynamic parameters affecting the stability of the excavation face. If the tunneling speed is too slow, the exposure time of the soil will be prolonged, and the penetration risk will be increased. If the tunneling speed is too fast, the stress release rate of the soil will exceed the response capacity of the mud support, and local collapse will be easily caused. In addition, a large additional load will be generated in the stratum, and the disturbance to the preceding shield and the surrounding rock will be caused. The penetration depth reflects the depth of the soil cut by the cutter head per rotation, and the relationship among the tunneling speed, the penetration depth and the cutter head speed is V=P x N (V is the tunneling speed, P is the penetration depth, and N is the cutter head speed). If the penetration depth is too large, the vibration of the cutter head and the disturbance to the soil will be intensified. Therefore, according to the control flow in the Figure 4 , the additional stress can be minimized by dynamically adjusting the support pressure of the tunnel face of the following shield.

[0202] Specifically, as shown in the Figure 4 , the tunneling speed, the static contact force, the tunneling contact force, the support pressure of the tunnel face and the static earth pressure of the preceding shield of the following shield are input through the database in step 1. The difference between the tunneling contact force and the static contact force of the following shield is the penetration resistance of the following shield, and the sum of the penetration resistance of the following shield and the support pressure of the tunnel face of the following shield is greater than the static earth pressure of the preceding shield. If the sum is greater than the static earth pressure of the preceding shield, it means that the additional stress of the following shield is too large, and the support pressure of the tunnel face of the following shield should be reduced. If the sum is less than or equal to the static earth pressure of the preceding shield, it means that the additional stress of the following shield is 0, and the following shield can be tunneled according to the current tunneling parameters.

[0203] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling of a shield tunneling machine, characterized in that, include: S1. Construct a multi-dimensional information database of the stratigraphic conditions in the docking area; The multidimensional information database includes geological parameters of the docking section, tunnel boring parameters, and spatiotemporal parameters of the docking section, which are used to extract the mechanical behavior characteristics of the preceding tunnel boring machine and the mechanical behavior characteristics of the subsequent tunnel boring machine. S2. Based on a multidimensional information database, analyze the structural resistance of the first shield tunnel, and determine the additional load on the first shield tunnel based on the additional load generated by the subsequent shield tunneling and the initial stress field around the first shield tunnel; the additional load on the first shield tunnel includes the indirect transmission load from the strata and the instantaneous collision load. S3. Based on the resistance of the preceding shield structure and the additional load on the preceding shield, establish a response evaluation system for the load-resistance ratio to determine the disturbance level, and adopt micro-disturbance control measures according to the disturbance level determination results; the micro-disturbance control measures include shield structure reinforcement, ground reinforcement of the docking section, and control of subsequent shield tunneling parameters; The method, based on a multidimensional information database, analyzes the structural resistance of the preceding shield tunnel and, based on the additional loads generated by the subsequent shield tunneling and the initial stress field around the preceding shield tunnel, determines that the additional loads borne by the preceding shield tunnel include: S21. Based on a multi-dimensional information database, the influence of shield tunneling downtime on the additional stress field in different strata is reproduced through numerical simulation in order to extract the previous shield tunneling downtime status. S22. Based on the shutdown status of the tunnel boring machine (TBM), the structural resistance of the TBM is evaluated by analyzing its compressive strength, torsional strength, and tensile strength. S23. By simulating the additional stress field during the subsequent shield tunneling and combining it with the initial stress field around the preceding shield, calculate the additional load on the preceding shield. The assessment results of the structural resistance of the preliminary shield tunnel, obtained by analyzing its compressive, torsional, and tensile strengths based on its shutdown status, include: S221. The compressive strength of the advance shield is obtained by superimposing the frictional resistance between the soil and the shield shell and the total bearing capacity of the weld of the shield tail anti-retreat steel plate; the frictional resistance between the soil and the shield shell increases with the increase of downtime. S222. Calculate the sum of the torsional friction resistance of the soil against the shield, the shear couple of the tail bolts and the segment bolts to obtain the torsional resistance of the advance shield; the torsional resistance is used to resist the torque transmitted to the tail when the rotating cutterhead of the follow shield collides with the cutterhead of the advance shield. S223. Combine the stratum frictional resistance and the tensile bearing capacity of the segment bolts to determine the tensile capacity of the advance shield, and combine the compressive and torsional capacity of the advance shield to obtain the assessment results of the structural resistance of the advance shield. The step of establishing a response evaluation system based on the resistance of the preceding shield structure and the additional loads on the preceding shield to determine the disturbance level includes: The resistance of the prior shield structure is compared with the additional load on the prior shield to establish a response evaluation system for the load-resistance ratio. Based on the comparison results of the load-resistance ratio assessment system, the disturbance level is divided into mild disturbance, moderate disturbance and severe disturbance. When the disturbance level is mild, automatic monitoring is triggered; when the disturbance level is moderate, the subsequent shield tunneling parameters are optimized; when the disturbance level is severe, micro-disturbance control measures are taken. The expression for the load-resistance ratio response evaluation system is as follows: ； In the formula, λ 压 , λ 扭 , λ 拉 These are respectively pressure disturbance level, torque disturbance level, and tensile disturbance level; T 碰撞 This represents the peak collision torque; ▽q 间接 For the transmission of load gradient; q 间接 F represents the indirect additional load on the surface of the tunnel boring machine (TBM); T represents the compressive strength of the TBM; T represents the torsional strength of the TBM; and L represents the tensile strength of the TBM.

2. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 1, characterized in that, The multidimensional information database for constructing the stratigraphic conditions of the docking zone includes: Based on geological exploration and permeability tests, permeability difference zones were delineated, and stratigraphic parameters of the connecting zones were obtained; wherein, the permeability difference zones include alternating layers of sand and clay; the stratigraphic parameters of the connecting zones include permeability coefficient, porosity, elastic modulus, and cohesion; Using the geological parameters of the docking section, combined with shield tunneling parameters and docking spatiotemporal parameters, a multidimensional information database is constructed; the shield tunneling parameters include shield tunneling speed, cutterhead penetration, mud pressure and grouting volume; the docking spatiotemporal parameters include the distance between the two shields, docking time difference, and shield attitude deviation. Based on the multidimensional information database, the influence of downtime difference on the additional stress field is analyzed, and Darcy's law and Biot's consolidation theory are applied to establish a dynamic coupling model of seepage-stress field to obtain the mechanical behavior characteristics of the preceding and subsequent shield tunnels.

3. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 1, characterized in that, The method, based on a multidimensional information database, uses numerical simulation to reproduce the impact of shield tunneling downtime on the additional stress field in different geological strata, in order to extract the preliminary shield tunneling downtime status, including: S211. Based on the geological condition parameters of the docking section and the shield tunneling parameters in the multidimensional information database, a three-dimensional finite element model is established to simulate the tunnel structure in the sand layer, clay layer and the state of the shield tunneling machine being stopped; the range of the three-dimensional finite element model is set according to the shield diameter to conform to the Saint-Venant principle. S212. Based on the geological condition parameters of the docking section, set up the material constitutive models of the sand layer and clay layer, and set the boundary conditions; S213. By simulating groundwater seepage, the pore water pressure calculated from the seepage field is coupled to the stress field as a volume force to update the effective stress, and the seepage-stress equation is obtained through coupling. S214. Using the seepage-stress equation, simulate the dissipation of excess pore water pressure and stress relaxation of the pilot shield under different downtime, and extract the additional stress of the nodes around the pilot shield.

4. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 3, characterized in that, The boundary conditions include: Fix the vertical displacement of the bottom of the model and apply normal constraints; Based on the actual hydrological conditions around the model, set free drainage boundaries, impermeable boundaries, or constant head; An initial stress field is generated around the tunnel boring machine by gravity loading, and the pore water pressure is distributed according to the hydrostatic pressure.

5. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 3, characterized in that, The expression for the simulated groundwater seepage is: ； In the formula, q is the seepage velocity; k is the permeability coefficient of the medium; μ is the dynamic viscosity of the fluid; ▽p is the pressure gradient; ρ l Where is the fluid density; g is the acceleration due to gravity; The expression for coupling the pore water pressure calculated from the seepage field as a volume force to the stress field to update the effective stress is as follows: σ'=σ-u; In the formula, σ' is the effective stress, which is used to determine the deformation and strength of the soil; σ is the total stress, which is generated by the external load and the self-weight of the soil; u is the pore water pressure, including hydrostatic pressure and excess pore water pressure. The coupling yields the following expression for the seepage-stress equation: ·(s')+r t g=0; In the formula, ·(σ') represents the additional stress; ρ t ρ is the soil density; g is the acceleration due to gravity.

6. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 1, characterized in that, The calculation of the additional load on the preceding shield tunnel by simulating the additional stress field during the subsequent shield tunneling, combined with the initial stress field around the preceding shield tunnel, includes: S231. By establishing a field coupling model, the spatiotemporal distribution of the additional stress field during the subsequent shield tunneling is simulated, and the evolution law of the subsequent additional stress field is extracted. S232. Combining the initial stress field around the first shield and the subsequent additional stress field, calculate the indirect ground-transmitted load and instantaneous collision load on the surface of the first shield to obtain the additional load on the first shield.

7. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 6, characterized in that, The method involves establishing a field coupling model to simulate the spatiotemporal distribution of the additional stress field during subsequent shield tunneling, and extracting the evolution law of the subsequent additional stress field, including: S2311. Based on a multidimensional information database, embed dynamic parameters to establish a field coupling model that couples seepage, stress, displacement, and material; wherein, the dynamic parameters include formation permeability coefficient, mud viscosity, and cutterhead penetration resistance, and the cutterhead penetration resistance is equal to the tunneling contact force minus the static contact force; S2312. Based on the field coupling model, the seepage path of mud is simulated by the fluid-structure interaction equation, and the stress field propagation range is analyzed by combining the Saint-Venant principle. S2313. The finite element method is used to simulate the spatiotemporal distribution of the additional stress field during the subsequent shield tunneling, and the stress gradient difference between the sand layer and the clay layer is quantified.

8. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 7, characterized in that, The finite element method is used to simulate the spatiotemporal distribution of the additional stress field during subsequent shield tunneling, quantifying the stress gradient difference between the sand and clay layers, including: A three-dimensional dynamic finite element model of the subsequent shield tunnel structure and strata is established; the model range of the three-dimensional dynamic finite element model conforms to Saint-Venant's principle to ensure that the boundary does not affect the stress field distribution; The unit dynamic activation technology is used to simulate the tunnel excavation process. Each time a ring is advanced, a ring of lining is activated and a ring of soil is removed. The cutterhead face support pressure and the shield tail grouting pressure are applied step by step as moving surface loads. Output full-field stress data according to preset time intervals, record the stress state at key time points, and draw three-dimensional stress cloud maps at different times; The stress gradient difference between the sand layer and the clay layer is quantified by using the maximum stress gradient.

9. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 8, characterized in that, The expression for quantifying the difference in stress gradient between the sand layer and the clay layer by using the maximum stress gradient is as follows: ； In the formula, G max The maximum stress gradient is used to characterize the extreme values ​​of principal stress variation per unit distance in the formation; The maximum principal stress change is used to characterize the maximum principal stress increment caused by subsequent shield tunneling. The minimum principal stress change is used to characterize the minimum principal stress increment caused by subsequent shield tunneling. Δ r The radial distance differential is used to characterize the change in radial distance between the center of the shield cutterhead after the calculation point distance.

10. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 6, characterized in that, The method combines the initial stress field around the advance shield and the subsequent additional stress field to calculate the indirect ground-transmitted load and instantaneous collision load on the surface of the advance shield, thereby obtaining the additional loads experienced by the advance shield, including: S2321. Extract the stress field generated by the subsequent shield tunneling, combine it with the initial stress field around the preceding shield, and use the nodal force difference method to calculate the indirect ground load transmitted to the surface of the preceding shield. S2322. Establish a three-dimensional model of the two cutterheads and the surrounding soil, and mesh the contact area of ​​the cutterheads; define the contact type between the cutterheads, use an explicit dynamic solver to perform transient analysis, and output the contact force time history curve to extract the instantaneous collision load; the instantaneous collision load includes the maximum load value, collision torque and action time.

11. The method for evaluating and controlling the response to superimposed disturbances during near-intersection tunneling as described in claim 10, characterized in that, The expression for calculating the indirectly transmitted load on the surface of the tunnel boring machine (TBM) using the nodal force difference method is as follows: ； In the formula, q 间接 For the indirect transfer of loads to the strata on the surface of the tunnel boring machine; ∑q 后行 (x,y,z) represents the stress field generated by the shield tunneling after the position (x,y,z); ∑q 先行初始 This represents the initial stress field around the tunnel boring machine.

12. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 1, characterized in that, The shield tunneling structure reinforcement includes: Determine the reinforcement range of the longitudinal segments of the shield tunnel and the length, width and thickness of the longitudinal reinforcement steel plate. Weld the longitudinal reinforcement steel plate to the anchoring steel plate and reinforce the shield tunnel longitudinally using the whole ring reinforcement method. On the assembled segments, anchor plates and rubber protective layers are installed by planting rebars. After the jacks are withdrawn, the welded steel plates are assembled as a whole in the corresponding positions of the segments. Anchor bolts are installed and sealing gaskets are tightened. After the entire ring of steel plates is installed, the steel plates are welded and fixed to the shield shell. The planar dimensions and weld range of the anti-reverse steel plate were determined, and the parameters of the anti-reverse steel plate were optimized based on the strength calculation results of the base material and weld of the anti-reverse steel plate.

13. The method for evaluating and controlling the response to superimposed disturbances during near-intercept tunneling as described in claim 12, characterized in that, The ground reinforcement of the docking section includes: Pressure-controlled grouting is carried out using the synchronous grouting system at the tail of the rear-moving shield. When the grouting pressure continues to rise to the set threshold, grouting is paused and left to stand until the pressure dissipates, at which point it is restarted. Based on the pre-set flushing pipeline of the slurry chamber of the tunnel boring machine, the reinforcing slurry is injected into the slurry chamber in stages, and the initial filling of the lower part, the pressure maintenance filling of the middle part, and the sealing filling of the upper part are carried out in sequence. Radial grouting and advanced grouting of the shield body are carried out in a bottom-to-top sequence through the pre-set radial grouting holes and advanced grouting holes on the shield shell.

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