Method and system for evaluating jamming risk of rear supporting system of tunnel boring machine

Abstract

The invention relates to the technical field of tunnel boring machines, in particular to a method and system for evaluating the machine jamming risk of a rear supporting system of a tunnel boring machine, and the method comprises the steps: building a surrounding rock mechanical model; loading the tunnel face space supporting effect, the initial lining supporting effect and the reserved space between the rear matching system and the initial lining as boundary conditions of the model into the surrounding rock mechanical model; the tunneling process is propelled in a time increment mode; calculating a convergence response of the lining / supporting member based on the rigidity and the mounting state of the current supporting member; comparing the obtained convergence differences; repeating the steps until a preset termination condition is reached; the maximum convergence value obtained through time sequence calculation is compared with the reserved space between the rear supporting system and the initial lining, a jamming risk warning is judged and output, dynamic coupling calculation of tunnel convergence and supporting pressure is achieved through numerical iteration, and therefore the accuracy of risk assessment and the reliability of construction control are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel boring machines, and relates to a method and system for evaluating the risk of a tunnel boring machine rear matching system being stuck. BACKGROUND

[0002] When a tunnel boring machine (TBM) is used to construct in soft surrounding rock or high ground stress stratum, it often faces problems such as significant convergence of surrounding rock, failure of the support system, and the rear matching system being stuck. Existing risk evaluation methods mostly rely on experience or a single elastic mechanics model, and cannot comprehensively consider the time-varying deformation characteristics of surrounding rock, the spatial effect of the working face, and the gradual stress process of the initial lining components. For example, some methods only use static force balance analysis to estimate support requirements, without introducing time factors and creep effects into the calculation, so it is difficult to accurately reflect the convergence evolution law of the surrounding rock under long-term shutdown or low excavation rate. On the other hand, the spatial reservation between the rear matching system and the initial lining often lacks dynamic checking in the construction design, and when the convergence of the surrounding rock exceeds the reserved space, the rear matching equipment is prone to being stuck, but the existing technology mostly stays at empirical assumptions and lacks accurate calculation methods that can be iteratively solved. In addition, traditional models often cannot unify the spatial support effect provided by the unexcavated rock mass of the working face and the stiffness evolution process of different lining components (such as steel arches, sprayed concrete, and anchor rods) into a calculation framework, resulting in obvious one-sidedness in risk evaluation.

[0003] In summary, the existing technology lacks a comprehensive calculation method that can simultaneously consider the viscoelastic-plastic time-varying characteristics of surrounding rock, the spatial effect of the working face, the lining support effect, and the construction conditions when evaluating the risk of the TBM rear matching system being stuck, resulting in insufficient prediction accuracy and the inability to provide reliable risk warnings and parameter optimization basis for construction. SUMMARY

[0004] To solve the problem that in existing TBM construction, the time-varying deformation characteristics of surrounding rock are not adequately described, the spatial support effect of the working face and the support effect of the initial lining are not comprehensively considered, and there is a lack of a rear matching system stuck risk prediction method based on quantitative criteria, resulting in risk evaluation relying on experience and lacking accuracy, and making it difficult to provide reliable basis for timely construction control, the present application proposes a method and system for evaluating the risk of a tunnel boring machine rear matching system being stuck.

[0005] The present application is implemented through the following technical solutions:

[0006] A method for evaluating the risk of a tunnel boring machine rear matching system being stuck, comprising the following steps:

[0007] S1, a surrounding rock mechanics model is established to represent the functional relationship between the deformation characteristics and support pressure of the surrounding rock under time evolution;

[0008] S2, loading the face space support effect, the initial lining support effect and the reserved space between the post-support system and the initial lining as the boundary conditions of the surrounding rock mechanics model;

[0009] S3, advancing the tunneling process in time increments, and calculating the surrounding rock convergence increment based on the current support pressure and the surrounding rock mechanics model at each time step;

[0010] S4, calculating the convergence response of the lining / support members based on the stiffness and installation state of the current support members;

[0011] S5, comparing the convergence difference obtained in steps S3 and S4, and updating the support pressure based on the difference, using numerical iteration until the convergence error is less than a preset threshold to determine the steady-state convergence and support pressure of the time step;

[0012] S6, repeating steps S3 to S5 until a preset termination condition is reached;

[0013] S7, comparing the maximum convergence value obtained by time series calculation with the reserved space between the post-support system and the initial lining, and determining and outputting a risk warning when the maximum convergence value exceeds the reserved space.

[0014] Further, the surrounding rock mechanics model uses a viscoelastic-plastic constitutive model to describe the creep characteristics of the surrounding rock and the convergence behavior under different support pressures.

[0015] Further, the face space support effect is characterized by a virtual support pressure related to the distance from the face, the tunneling rate and time, and the support pressure distribution in the model is corrected with the virtual support pressure.

[0016] Further, the initial lining support effect is determined by the equivalent stiffness and maximum allowable convergence value of a number of support members, including but not limited to steel arches, sprayed concrete and anchor rods, and each support member is effective at its installation location and its stiffness contribution is sequentially superimposed.

[0017] Further, the numerical iteration is an iterative solution based on pressure increments and convergence increments, and the iteration convergence condition is that the convergence difference is less than a preset error threshold, which is a settable numerical parameter.

[0018] Further, when the convergence of the support members reaches the respective maximum allowable convergence value, the equivalent stiffness of the support members is set to zero to simulate support failure, and the total stiffness of the system and the support pressure are recalculated accordingly.

[0019] Further, a critical value of the tunneling rate is determined based on parameter scanning or sensitivity analysis, so that when the tunneling rate is lower than the critical value, the maximum convergence calculated by the surrounding rock mechanical model exceeds the reserved space, and the construction control suggestion is output.

[0020] The application further provides a system for evaluating the risk of a tunnel boring machine rear supporting system being stuck, comprising:

[0021] a modeling unit configured to establish a mechanical model representing the evolution of surrounding rock over time;

[0022] a parameter input unit configured to input geological parameters, supporting member parameters, a reserved space, a tunneling rate and shutdown information; a calculation unit configured to calculate the surrounding rock convergence increment and the lining convergence increment in each time step in time increments and iteratively solve the steady-state convergence and support pressure;

[0023] a correction unit configured to correct the support pressure based on the space effect of the tunnel face;

[0024] a discrimination unit configured to compare the maximum convergence value obtained by solving with the reserved space and output the risk evaluation result of the tunnel boring machine rear supporting system being stuck and related alarm information;

[0025] a display / storage unit configured to present the time series convergence curve, the support pressure distribution and the evaluation conclusion and save the calculation record.

[0026] The application has the following beneficial effects:

[0027] (1) The application adopts a viscoelastic plastic constitutive model, describes the creep effect and plastic deformation process of surrounding rock through the time function of the equivalent shear modulus and Poisson's ratio, can not only reflect the instantaneous deformation of surrounding rock in a short period of time, but also simulate the convergence gradually accumulated when the machine is stopped or the tunneling rate is low, solves the problem that the existing method cannot reflect long-term deformation, and guarantees the accuracy of risk evaluation, thereby providing a solid foundation for long-term stability analysis under construction conditions;

[0028] (2) The application converts the space support provided by the unexcavated rock mass of the tunnel face into a correction term varying with time, tunneling rate and distance of the tunnel face, which is more reasonable than the traditional simplified support assumption, can effectively simulate the inhibition of the tunnel face on the convergence of surrounding rock under different tunneling speeds, and avoids the calculation deviation caused by underestimating the initial support capacity;

[0029] (3) The application superimposes the stiffness of various supporting members such as steel arches, sprayed concrete and anchor rods, and considers the installation sequence and the maximum allowed convergence value. When a supporting member reaches the limit deformation, the equivalent stiffness is automatically set to zero, so as to accurately simulate the dynamic process of the step-by-step effectiveness and failure of the support. Compared with the existing method which assumes that the support stiffness is constant, the application significantly improves the authenticity of the support effect calculation.

[0030] (4) The application adopts time increment promotion and pressure increment iteration, in each time step, the support pressure is corrected by calculating the difference between the convergence of surrounding rock and the convergence of lining, until the error is less than the preset threshold, which ensures the consistency between the convergence and the support pressure and the stability of calculation, avoiding the problem of non-convergence or error accumulation caused by single static solution;

[0031] (5) The application compares the maximum convergence value obtained by numerical simulation with the reserved space between the post-supporting system and the initial lining, when the maximum convergence value exceeds the reserved space, it is automatically determined that there is a risk of machine jamming and warning information is output, avoiding the defects of rough judgment relying on experience value only, and realizing the quantification and operability of risk prediction;

[0032] (6) The application obtains the critical value of the tunneling rate through parameter scanning and sensitivity analysis, that is, when the rate is lower than the critical value, the maximum convergence of surrounding rock will exceed the reserved space, which is directly recommended for construction control and provides quantitative basis for construction organization, solving the problem that the tunneling rate is set by experience in the traditional way;

[0033] (7) The application further proposes a supporting system, including a modeling unit, a parameter input unit, a calculation unit, a correction unit, a discrimination unit and a display / storage unit, which can realize the whole process calculation and visualization from parameter input, model solution to result determination and warning output. The system can be directly applied in the construction site, supports real-time warning and data archiving, and improves the informatization and intelligentization level of construction.

[0034] In summary, the application can comprehensively consider the viscoelastic and plastic time-varying characteristics of surrounding rock, the space effect of the tunnel face and the supporting effect of the initial lining, realize the dynamic coupling calculation of tunnel convergence and support pressure through numerical iteration, and determine the risk of machine jamming of the post-supporting system according to quantitative criteria, thereby significantly improving the accuracy of risk assessment and the reliability of construction control. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 A flow chart of a method for evaluating the risk of machine jamming of the post-supporting system of the tunnel boring machine is proposed in the application;

[0037] Figure 2A CVISC model schematic diagram for evaluating the risk of a tunnel boring machine rear supporting system jamming is proposed in the present application.

[0038] Figure 3 A space support effect diagram of a tunnel boring machine in a tunnel excavation process is proposed in the present application.

[0039] Figure 4 An open-type tunnel boring machine schematic diagram of different support components is proposed in the present application.

[0040] Figure 5 A terminal device schematic diagram of a system for evaluating the risk of a tunnel boring machine rear supporting system jamming is proposed in the present application.

[0041] Figure 6 A readable storage medium schematic diagram of a system for evaluating the risk of a tunnel boring machine rear supporting system jamming is proposed in the present application.

[0042] In the figure, 200 is a terminal device, 210 is a memory, 211 is a RAM, 212 is a cache, 213 is a ROM, 214 is a program / utility, 215 is a program module, 220 is a processor, 230 is a bus, 240 is an external device, 250 is an I / O interface, 260 is a network adapter, and 300 is a program product. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application is further described in detail below with reference to examples and drawings, the schematic embodiments of the present application and the description thereof are only used to explain the present application, and do not limit the present application.

[0044] Example 1

[0045] Reference Figure 1 The present embodiment provides a method for evaluating the risk of a tunnel boring machine rear supporting system jamming. In the present embodiment, the method is applied to the construction scene of an open-type tunnel boring machine under high plateau stress soft ground conditions, for example, a certain mountain tunnel project. The tunnel is a circular tunnel with a diameter of about 8.4 meters, with a burial depth of more than 600 meters, and the surrounding rock is mainly composed of sandstone and mudstone, facing the risk of large deformation. The method establishes a surrounding rock mechanical model to represent the functional relationship between the deformation characteristics of the surrounding rock under time evolution and the support pressure.

[0046] Firstly, in step S1, a surrounding rock mechanical model is established. The model adopts a viscoelastic-plastic constitutive model to describe the creep characteristics of the surrounding rock and the convergence behavior under different support pressures. Specifically, the surrounding rock mechanical model is a Burgers creep viscoelastic-plastic CVISC model as shown in Figure 2The model consists of a Burgers body and a slider, used to simulate viscoelastic and plastic behavior, respectively. The Burgers model is composed of a Maxwell model and a Kelvin model in series, and its equivalent shear modulus and Poisson's ratio are expressed by the following formulas:

[0047]

[0048] Where G(t) is the time-dependent equivalent shear modulus, in units of (Pa), and η M This is the viscosity in Maxwell's model, measured in Pa·s, G. M The shear modulus of the Maxwell model is expressed in Pa, η. K The viscosity expressed in the Kelvin model is measured in Pa·s (G). K It is the shear modulus of the Kelvin model, with units of (Pa).

[0049] This model assumes that the rock mass material is homogeneous and isotropic, following the Mohr-Coulomb failure criterion, where the slider is controlled by the Mohr-Coulomb constitutive model, and its yield criterion is expressed by the formula:

[0050]

[0051] The potential function for using the non-associated flow rule is:

[0052] g = σ θ -K ps σ r (4); where K ps Indicates the coefficient of thermal expansion;

[0053] K ps = (1+sinφ) / (1-sinφ); where φ represents the expansion angle.

[0054] The total strain in the CVISC model consists of viscoelastic and plastic components. According to the Prandtl-Royce flow law for small deformations, the increments of tangential and radial strain around the tunnel can be written as:

[0055]

[0056] Where dε θ , These are the total tangential strain increment, the viscoelastic tangential strain increment, and the plastic tangential strain increment, respectively, dε r , These are the total radial strain increment, the viscoelastic radial strain increment, and the plastic radial strain increment, respectively, with the plastic strain increment shown below:

[0057] in is the plastic strain component, λ is the plastic multiplier, σ ij is the stress component.

[0058] The viscoelastic strain is the deviatoric strain, which only depends on the deviatoric stress s ij Therefore, the equation of the viscoelastic strain can be expressed according to the formula of the time-dependent equivalent shear modulus:

[0059] where s ij is the deviatoric stress component, σ kk represents the volumetric stress component, K represents the bulk modulus, is the viscoelastic strain, δ ij is the ring hammer calculation.

[0060] The tangential stress and the radial stress in the elastic zone and the plastic zone are respectively expressed by the following formulas:

[0061]

[0062] where σ r and σ θ are the radial stress and the tangential stress, respectively, with the unit of (Pa), P i is the support pressure applied on the excavation boundary, with the unit of (Pa), r represents the radius, with the unit of (m); r i represents the inner radius of the tunnel, with the unit of (m), r p is the radius of the plastic zone, with the unit of (m); P0 is the initial in-situ stress, σ rp is the radial stress on the boundary between the elastic zone and the plastic zone, with the unit of (Pa); σ c is the uniaxial strength, with the unit of (Pa), is the friction angle, and

[0063] The radius of the elastic-plastic boundary is calculated by the following formula:

[0064]

[0065] The tangential and radial viscoelastic strains around the circular tunnel are solved by the following formulas:

[0066]

[0067] where u is the displacement of the rock mass around the tunnel, with the unit of (m), and formula (9) is substituted into formula (12) to obtain the displacement in the elastic zone as follows:

[0068]

[0069] Substituting equation (13) into equation (7), the tangential and radial plastic strain are represented by equations (14) and (15), respectively:

[0070]

[0071]

[0072] The plastic strain increment in the plastic zone always follows the correlation in equation (17):

[0073]

[0074] Substituting equations (5) and (6) into equation (16) gives:

[0075]

[0076] Further combining equations (10) and (12), equation (17) can be rewritten as:

[0077]

[0078] Integrating equation (18) and considering the elastic-plastic boundary continuity condition u p (r p ) = u e (r p ), the plastic zone radial displacement equation is obtained:

[0079]

[0080] where

[0081] Letting r = r i , the convergence of the tunnel can be written as:

[0082]

[0083] In equations (19) and (22), time and support pressure are the only variables, and all other parameters are constants determined by material properties and geometry. The time-dependent displacement of the surrounding rock is simulated by the equivalent shear modulus G(t) and Poisson's ratio v(t). This model ensures that the deformation of the surrounding rock is a function of the support pressure, and this functional relationship contains the material parameters and geometric parameters of the surrounding rock as constant inputs. In this embodiment, the model is verified by numerical simulation, which is consistent with the results of FLAC3D. The convergence evolution is divided into a primary stage (rapid increase but decreasing rate) and a secondary stage (constant rate of increase).

[0084] For a mountain tunnel, the surrounding rock parameters are set to the bulk modulus K = 10.0 GPa in this embodiment, and the shear modulus GM = 4.6 GPa, Maxwell model viscosity η M = 4.12 x 10 5 GPa s, Kelvin model shear modulus G K = 1.0 GPa, Kelvin model viscosity η K = 5.12 x 10 3 GPa s, friction angle = 15°, cohesion c = 2.3 MPa, initial hydrostatic pressure P0 = 30 MPa, tunnel radius r i = 4.2 m, the above parameters are verified by field data to ensure that the model accurately describes the time-dependent deformation of the surrounding rock under high in-situ stress, for example, the creep behavior can account for more than 70% of the total deformation.

[0085] Reference Figure 3 In step S2, the face space support effect, the initial lining support effect, and the reserved space between the post-supporting system and the initial lining are loaded as boundary conditions of the model into the surrounding rock mechanical model. Specifically, the face space support effect is characterized by a virtual support pressure related to the distance from the face, the tunneling rate, and the time, and the virtual support pressure is corrected by the formula:

[0086] The support pressure distribution in the corrected model of the virtual support pressure, the effect is represented by the coefficient λ e :

[0087] where λ e is the coefficient of the tunnel face space effect, X represents the distance from the tunnel face, in (m), X * represents the influence range of the tunnel face space effect, in this embodiment X * = 3r i , the distance from the face X is calculated by the formula:

[0088] X = Vt (24); where V is the tunneling rate of the TBM, in (m / s), and t represents the tunneling time, in (s). The virtual support pressure is calculated by the formula:

[0089] P a (V, t) = (1 - λ e (V, t))P0 (25); where P a (V, t) is the virtual pressure, in (Pa).

[0090] The virtual pressure is dynamically adjusted to simulate the restriction of the face to the surrounding rock deformation and is loaded into the model as a boundary condition to correct the support pressure. In some mountain tunnel applications, this effect results in a convergence that starts from a non-zero value near the face and increases significantly as the spatial effect weakens. The initial lining support effect is determined by the equivalent stiffness and the maximum allowed convergence of several support members, including but not limited to steel arch, shotcrete and anchor, and each support member is effective at its installed position and its stiffness contribution is superimposed in sequence.

[0091] Reference Figure 4 In particular, the initial lining is composed of steel arch, shotcrete and anchor, and the installation is divided into L1 and L2 sections, the steel arch is installed at X1 from the face, and the shotcrete is installed at the L2 section. The effect of different support members is determined by the support stiffness K, the maximum support pressure P max and the maximum allowed convergence u max For steel arch:

[0092]

[0093] where K ste is the support stiffness of the steel arch, with a unit of (Pa), E ste represents the Young's modulus of steel, with a unit of (Pa), A ste is the cross-sectional area of the steel arch, with a unit of (m 2 ), d represents the spacing of the steel arch in the longitudinal direction, with a unit of (m), h ste is the height of the cross section of the steel arch, with a unit of (m), P max，ste is the maximum allowed support pressure, with a unit of (Pa), σ ste，y is the yield strength of the steel arch, with a unit of (Pa), and ε br,ste is the ultimate strain at failure.

[0094] For shotcrete:

[0095]

[0096] where K sho is the support stiffness of the shotcrete, with a unit of (Pa), E con represents the Young's modulus of concrete, with a unit of (Pa), v con represents the Poisson's ratio of concrete, t sho is the thickness of the shotcrete, with a unit of (m), σ c is the compressive strength of concrete, with a unit of (Pa), P max，sho is the maximum allowed support pressure of the shotcrete, with a unit of (Pa), and ε br，sho is the ultimate strain at failure.

[0097] For the anchor rod:

[0098]

[0099] u max,bol = u in,bol + ε br,ste L bol (34).

[0100] where K bol is the support stiffness of the anchor rod, in (Pa), L bol represents the length of the anchor rod, in (m), S t and S l are the spacing of the anchor rod in the circumferential and longitudinal directions, respectively, in (m), Φ is the diameter of the anchor rod, in (m), E ste is the Young's modulus of steel, in (Pa), Q represents the load-deformation characteristic constant, in (m / N), P max，bol represents the maximum allowable support pressure, in (Pa), T max is the yield force of the anchor rod-rock mass system, in (Pa), ε br，ste is the ultimate strain at failure, u max，bol is the maximum allowable convergence of the anchor rod.

[0101] In this embodiment, the parameters are set as:

[0102] Steel frame parameters:

[0103] E ste = 206 GPa, A ste = 3.95 x 10 -3 m 2 , d = 0.5 m, h ste = 0.2 m, σ ste，y = 345 MPa;

[0104] Shotcrete parameters:

[0105] E con = 16.5 GPa, v con = 0.2, t sho = 0.2 m, σ c = 30 MPa;

[0106] Anchor rod parameters:

[0107] S t = 1.25 m, S l = 1.25 m, Φ = 0.025 m, E bol = 200 GPa, T max = 150 kN;

[0108] The total stiffness of multiple supporting members is determined by the formula:

[0109]

[0110] Where K s，tot It is the total stiffness of the multi-support system, expressed in Pa (K). s，j u is the stiffness of the supporting member j, expressed in Pa. in，j It is the tunnel convergence amount during the installation of supporting component j, with units of (m). The function H(x) is defined as follows:

[0111]

[0112] Given the stiffness of the support system, the support pressure of the system can be calculated using the following formula:

[0113] ΔP s =K s，tot Δu i / r i (37);

[0114] If any support system fails, its supporting effect will be lost; therefore, the maximum convergence of the tunnel will be determined by the minimum u in the support system. max，j The decision is as shown in formula (38):

[0115] u max，tot =min[u max，j (38);

[0116] The maximum support pressure is then estimated using formula (39):

[0117] P max,tot =∑ j p s，j (39);

[0118] The reserved space Δr between the post-supporting system and the initial lining g As a boundary condition, it is set as Δr in this embodiment. g =0.35m (considering the initial lining thickness), used for subsequent judgment, when the tunnel convergence exceeds Δr g When a machine freezes, the determination is described by the following formula:

[0119] Δr g >u i,max (40);

[0120] Where Δr g This represents the minimum reserved space between equipment and supporting components in the backup section, expressed in meters (m). i，max This represents the maximum convergence amount entering the TBM segment, expressed in meters (m).

[0121] In step S3, the tunneling process is advanced in time increments, and the surrounding rock convergence increment is calculated at each time step based on the current support pressure and the surrounding rock mechanical model. Specifically, the time step At is set to 1 hour or adjusted according to accuracy, and the tunneling process is advanced by the formula:

[0122] t n+1 = t n + At (41) ;

[0123] X n+1 = f(V, t n+1 ) (42) ;

[0124] where X n+1 is the tunneling distance in (m), and V is the tunneling rate in (m / day).

[0125] The convergence increment of the surrounding rock is calculated by the formula:

[0126]

[0127] where and are the partial derivatives from formula (22), and the increment is based on the time increment and the pressure increment. In this embodiment, this step simulates the tunneling scheme, including periodic excavation and shutdown, and the exposure time of the surrounding rock affects the creep behavior, resulting in a rapid increase in the convergence increment near the working face.

[0128] In step S4, the convergence response of the lining / support member is calculated based on the stiffness and installation state of the current support member. Specifically, the convergence increment of the lining is determined by the formula:

[0129]

[0130] where K s，tot is from formula (35), considering the sequential installation and stiffness superposition of the support member, and if the convergence amount reaches u max，j , the support member fails, its equivalent stiffness is set to zero to simulate support failure, and the total stiffness of the system and the support pressure are recalculated accordingly, for example, the stiffness of the steel arch is set to zero when it fails at X > 125 m, and the support pressure is adjusted accordingly.

[0131] In this embodiment, the response is consistent with the field data, and the convergence rate after installation decreases from 25 mm / day to 2.5 mm / day.

[0132] In step S5, the convergence difference of step S3 and step S4 is compared, and the support pressure is updated based on the difference, and the numerical iteration is adopted until the convergence error is less than the preset threshold to determine the steady-state convergence and the support pressure of the time step. Specifically, the convergence difference is calculated by the formula:

[0133]

[0134] The numerical iteration is an iterative solution based on the pressure increment and the convergence increment, and the iterative convergence condition is that the convergence difference is less than the preset error threshold, and the error threshold is a settable numerical parameter. In the embodiment, the threshold is set to 10 -5 (corresponding to 1% error within 1mm accuracy), when R<10 -5 , the support pressure is updated by the formula:

[0135] P s，n+1 =P s，n +ΔP s (46);

[0136] The virtual pressure and the total support pressure are calculated by the formula:

[0137] P i，n+1 =P a，n+1 +P s，n+1 (47);

[0138] The convergence displacement is calculated by the formula:

[0139] u i，n+1 =u i，n +K s，tot Δu i，n+1 (P s，n , t n , ΔP s , Δt) (48);

[0140] wherein P s，n+1 represents the support pressure of the current time step, with the unit of (Pa), P a，n+1 represents the virtual pressure under the effect of the tunnel face, with the unit of (Pa), u i，n+1 is the convergence amount of the current time step, with the unit of (m), and the iterative process ensures the coupled solution of the convergence amount and the support pressure. In the embodiment, the support pressure decreases from the face 20MPa to a lower level and then rises.

[0141] In step S6, steps S3 to S5 are repeated until the preset termination condition is reached. In the embodiment, the termination condition is that the simulation time reaches 600 days or the convergence is stable, and the repeated process generates a time-series convergence curve, for example, the maximum convergence amount reaches u i，max =0.38m.

[0142] In step S7, the maximum convergence value calculated by the time sequence is compared with the reserved space between the post-matching system and the initial lining. When the maximum convergence value exceeds the reserved space, a risk warning of machine jamming is determined and output. Specifically, the formula (40) is used for discrimination:

[0143] Δu max (t)≥Δr g If the condition is met, the system outputs a machine jamming risk prompt information. For example, the warning can be triggered under certain excavation rate conditions. The method also includes determining the critical value of the excavation rate based on parameter scanning or sensitivity analysis, i.e. when the excavation rate is lower than the critical value, the maximum convergence calculated by the surrounding rock mechanical model exceeds the reserved space, thereby serving as a basis for construction control discrimination.

[0144] In this embodiment, by parameter scanning of different excavation rates, the corresponding critical excavation rate can be determined, and when the excavation rate is lower than this value, the risk of machine jamming significantly increases. At the same time, under the condition of long-term shutdown, the model calculation shows that the convergence will continue to increase and eventually exceed the reserved space to trigger the warning. Further, the installation position of the anchor rod and the sprayed concrete has an impact on the convergence process, and when the lining component is installed late, the convergence increases more significantly, so the installation timing of the component should be reasonably arranged in combination with the model results. For steel arch support, the calculation results show that increasing its stiffness has limited effect on the overall convergence control, but when the steel arch yields, the numerical simulation shows that its internal force tends to be stable, the supporting capacity decreases, and it is easy to lead to further convergence expansion.

[0145] The method not only gives the dynamic evolution trend of the risk of machine jamming through numerical calculation, but also outputs the construction control conditions in combination with parameter analysis, including the safe interval under different excavation rates, the risk evolution law of long-term shutdown, and the rationality discrimination of the timing arrangement of supporting components.

[0146] Embodiment 2

[0147] Based on the method proposed in embodiment 1, this embodiment further provides a system for evaluating the risk of machine jamming of the post-matching system of a tunnel boring machine. The system is realized by combining hardware and software, mainly composed of a modeling unit, a parameter input unit, a calculation unit, a correction unit, a discrimination unit, and a display / storage unit. The units are coupled through a data bus or a software interface to ensure efficient data transmission and calling in each processing link within the system.

[0148] Firstly, the modeling unit is used to establish a mechanical model representing the evolution of surrounding rock over time. This unit calls the preset viscoelastic plastic constitutive relation and uses time-dependent parameter functions to describe the stress-strain evolution law of surrounding rock. The model is based on the CVISC model, which reflects the instantaneous deformation and time-dependent creep effect of surrounding rock by connecting and parallel connecting viscous elements and elastic elements. During modeling, the modeling unit calls formulas (1) to (22) to gradually derive and calculate the elastic modulus, viscosity parameters, Poisson's ratio, and equivalent modulus. The unit specifically performs step S1, outputs a mathematical expression that can represent the response of surrounding rock under time-series loading, forms a complete mechanical model framework, and provides a unified model interface for subsequent calculation unit calls.

[0149] Secondly, the parameter input unit is used to input various engineering parameters required for calculation. This unit supports the input of geological parameters, including the initial stress state of surrounding rock, stratum distribution characteristics, and mechanical parameters; the input of support member parameters, including anchor rod arrangement, steel arch stiffness, and shotcrete thickness; the input of construction condition parameters, including excavation rate, downtime, position of the working face, and installation position of the rear supporting system; in addition, it also includes the input of reserved space for comparison and discrimination with the calculated convergence. The design of the parameter input unit ensures that the system can cover the calculation needs of various working conditions, and the input data can be completed through manual input, database call, or real-time transmission from on-site monitoring equipment, and stored in a unified format for subsequent calculation calls.

[0150] After the parameters are input, the calculation unit is responsible for simulating the convergence process of surrounding rock in time increments. The unit implements steps S3 to S6 by calculating the convergence increment of surrounding rock and the convergence increment of the lining at each time step, and then iteratively solving the convergence equilibrium state and the evolution process of support pressure. The calculation unit core calls formulas (41) to (48) to update the stress field and displacement field distribution in each iteration cycle and determine whether the convergence condition is met. When the convergence condition is met, the calculation unit outputs the steady-state convergence value and the corresponding support pressure curve. The implementation of this unit ensures the continuity and timeliness of the calculation process, and can reflect the coupled deformation process of surrounding rock and support under different excavation rates and different downtime conditions.

[0151] To improve the authenticity of the calculation results, the system sets a correction unit. This unit is used to correct the support pressure based on the space effect of the working face. In actual construction, the space effect of the working face causes changes in the stress state of surrounding rock, and relying only on one-dimensional or two-dimensional models often cannot accurately reflect it. Therefore, the correction unit calls formulas (23) to (25) to add a working face influence factor when calculating the support pressure to correct the pressure distribution. The output of the correction unit can more accurately reflect the stress release and support bearing of surrounding rock near the working face, making the overall calculation results closer to the actual engineering state.

[0152] After the convergence calculation and pressure correction are completed, the discrimination unit plays a key role. This unit compares the calculated maximum convergence value with the reserved space, makes a logical discrimination based on formula (40). If the maximum convergence value is greater than or equal to the reserved space, it is determined that there is a risk of jamming, and the risk assessment result and alarm information are output; if the critical condition is not reached, the output is a safe state. The discrimination unit not only provides the final risk conclusion, but also stores the risk level and triggering condition together to form a standardized discrimination logic, so as to facilitate quick comparison and application in the construction process.

[0153] Finally, the display / storage unit is used to present the calculation results and evaluation conclusions of the system. This unit outputs the time series convergence curve, support pressure evolution distribution, working face correction result and jamming risk discrimination result in the form of charts or reports, so that the key information can be intuitively obtained by construction personnel or design personnel. At the same time, the display / storage unit has a historical data storage function, which archives the parameters input for each calculation, the intermediate results of model calculation and the final discrimination conclusions. The archived data can be called when subsequent construction scheme optimization or risk review is performed, forming a systematic engineering database.

[0154] The system for evaluating the jamming risk of the rear supporting system of the tunnel boring machine provided in the embodiment can realize the whole process closed loop of modeling, parameter input, iterative calculation, working face correction, risk discrimination and result storage under a unified framework. Through the system, the convergence and support response relationship can be quickly obtained under different geological conditions and construction conditions, and the jamming risk conclusion can be output based on the comparison of convergence and reserved space, so as to provide scientific risk identification and evaluation support for the subsequent tunneling construction process.

[0155] Embodiment 3

[0156] Reference Figure 5 On the basis of embodiment 1, the terminal device of the system for evaluating the jamming risk of the rear supporting system of the tunnel boring machine is proposed in the embodiment, and the terminal device 200 includes at least one memory 210, at least one processor 220 and a bus 230 connecting different platform systems.

[0157] The memory 210 can include a readable medium in the form of a volatile memory, such as a RAM 211 and / or a cache 212 memory, and can further include a ROM 213.

[0158] The memory 210 also stores a computer program, which can be executed by the processor 220, so that the processor 220 executes the application of any one of the above-mentioned systems for evaluating the risk of jamming of the tunneling machine rear supporting system in the embodiments of the present application. The specific implementation manners and the achieved technical effects are consistent with those described in the embodiments of the above-mentioned application, and part of the content will not be described herein again. The memory 210 can also include programs / utilities 214 having a set of (at least one) program modules 215, which include but are not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination thereof can include the implementation of a network environment.

[0159] Correspondingly, the processor 220 can execute the above-mentioned computer program, and can execute the program / utilities 214.

[0160] The bus 230 can represent one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor or a local bus using any of a variety of bus structures.

[0161] The terminal device 200 can also communicate with one or more external devices 240, such as a keyboard, a pointing device, a Bluetooth device, etc., and can also communicate with one or more devices capable of interacting with the terminal device 200, and / or with any device (such as a router, a modem, etc.) that enables the terminal device 200 to communicate with one or more other computing devices. Such communication can be carried out through the I / O interface 250. In addition, the terminal device 200 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network such as the Internet) through the network adapter 260. The network adapter 260 can communicate with other modules of the terminal device 200 through the bus 230. It should be understood that although not shown in the figure, other hardware and / or software modules can be used in conjunction with the terminal device 200, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms, etc.

[0162] Embodiment 4

[0163] The present embodiment proposes a readable storage medium of a system for evaluating the risk of jamming of the tunneling machine rear supporting system, and the computer readable storage medium stores instructions, which are executed by a processor to implement any one of the above-mentioned systems for evaluating the risk of jamming of the tunneling machine rear supporting system. The specific implementation manners and the achieved technical effects are consistent with those described in the embodiments of the above-mentioned application, and part of the content will not be described herein again.

[0164] Figure 6A program product 300 for implementing the above application provided by the embodiment is shown, which can adopt a portable compact disc read-only memory (CD-ROM) and include program codes, and can run on a terminal device, such as a personal computer. However, the program product 300 of the present application is not limited to this, and in the embodiment, the readable storage medium can be any tangible medium containing or storing a program, which can be used by or in combination with an instruction execution system, device or apparatus. The program product 300 can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include an electrical connection having one or more wires, a portable disc, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0165] The computer readable storage medium can include a data signal transported in a baseband or as part of a carrier wave, and can be readable by a computer. Such a propagated signal can take a wide variety of forms, including but not limited to electro-magnetic, optical, or any suitable combination thereof. A computer readable medium can also be any medium that can be read by a computer, including but not limited to any medium that stores, transmits, or receives the program code. The program code contained on the computer readable storage medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical fiber cable, RF, etc., or any suitable combination thereof. The program code can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C++, etc., and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computing device, partly on the user's computing device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device or entirely on the remote computing device or server. In the latter scenario, the remote computing device can be connected to the user's computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computing device, such as through the Internet using an Internet Service Provider.

[0166] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine, characterized in that, Includes the following steps: S1. Establish a surrounding rock mechanics model to characterize the functional relationship between the deformation characteristics of the surrounding rock and the support pressure under time evolution; S2. The spatial support effect of the working face, the initial lining support effect, and the reserved space between the subsequent supporting system and the initial lining are loaded into the surrounding rock mechanics model as boundary conditions of the model. S3. Advance the tunneling process in a time increment manner, and calculate the surrounding rock convergence increment based on the current support pressure and the surrounding rock mechanics model in each time step; S4. Calculate the convergence response of the lining / support components based on the current stiffness and installation status of the supporting components; S5. Compare the convergence difference obtained in step S3 and step S4, and update the support pressure based on the difference. Use numerical iteration until the convergence error is less than a preset threshold to determine the steady-state convergence and support pressure at this time step. S6. Repeat steps S3 to S5 until the preset termination condition is met. S7. Compare the maximum convergence value obtained by time series calculation with the reserved space between the subsequent supporting system and the initial lining. When the maximum convergence value exceeds the reserved space, determine and output a machine jam risk warning.

2. The method for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine according to claim 1, characterized in that, The surrounding rock mechanics model adopts a viscoelastic-plastic constitutive model to describe the creep characteristics of the surrounding rock and its convergence behavior under different support pressures.

3. The method for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine according to claim 1, characterized in that, The spatial support effect at the tunnel face is characterized by virtual support pressure related to the distance to the tunnel face, tunneling rate, and time, and the support pressure distribution in the model is corrected by this virtual support pressure.

4. The method for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine according to claim 1, characterized in that, The initial lining support effect is determined by the equivalent stiffness and maximum allowable convergence value of several support components, including but not limited to steel arches, shotcrete and anchor bolts. Each support component takes effect at its installation position and its stiffness contribution is superimposed sequentially.

5. The method for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine according to claim 1, characterized in that, The numerical iteration is an iterative solution based on pressure increment and convergence increment. The convergence condition is that the convergence difference is less than a preset error threshold, which is a settable numerical parameter.

6. The method for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine according to claim 1, characterized in that, When the convergence of the support components reaches their respective maximum allowable convergence values, their equivalent stiffness is set to zero to simulate support failure, and the total stiffness and support pressure of the system are recalculated accordingly.

7. The method for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine according to claim 1, characterized in that, It also includes determining a critical value for the tunneling rate based on parameter scanning or sensitivity analysis, such that when the tunneling rate is lower than the critical value, the maximum convergence amount calculated by the surrounding rock mechanics model exceeds the reserved space, and is output as a construction control suggestion.

8. A system for assessing the risk of machine jamming in the downstream systems of a tunnel boring machine, characterized in that, include: Modeling units are used to establish mechanical models that characterize the evolution of surrounding rocks over time; The parameter input unit is used to input geological parameters, support component parameters, reserved space, tunneling rate and shutdown information; The calculation unit is used to calculate the convergence increment of the surrounding rock and the convergence increment of the lining in each time step with time increments and to perform iterative solutions to obtain steady-state convergence and support pressure. Correction unit, used to correct support pressure based on the spatial effect of the working face; The discrimination unit is used to compare the maximum convergence value obtained by the solution with the reserved space and output the card machine risk assessment result and related alarm information. The display / storage unit is used to present the timing convergence curve, support pressure distribution, evaluation conclusions, and save calculation records.

Images