Numerical simulation method of tunnel construction considering time-space effect of mechanical properties of supporting materials
Patent Information
- Application Number
- CN202611048412.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-15
- Publication Date
- 2026-08-18
AI Technical Summary
[0007]本发明的目的是提供考虑支护材料力学性能时空效应的隧道施工数值模拟方法，解决现有隧道施工数值模拟方法中，将喷射混凝土力学性能参数简化为恒定值，忽略其随龄期演化的“时空效应”，导致模拟结果与工程实际偏差较大的技术问题
（1）提高了数值模拟的精度和真实性。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of numerical simulation technology for tunnel engineering, and in particular to a numerical simulation method for tunnel construction that considers the spatiotemporal effects of the mechanical properties of support materials. Background Technology
[0002] During tunnel construction, the deformation control of the surrounding rock is closely related to the design of the initial support structure. The characteristic curve theory of the surrounding rock-support system indicates that the bearing capacity of the initial support and its timing of construction have a significant impact on the stress redistribution and deformation development of the surrounding rock. As a key component of the initial support, the hardening process of shotcrete before reaching its ultimate strength plays a decisive role in the critical failure of the support structure.
[0003] Currently, some progress has been made in the research on the mechanical properties of shotcrete. Studies have shown that since the critical failure of the initial support of tunnels usually occurs before the shotcrete reaches its ultimate strength, it is particularly important to fully consider the early hardening characteristics of shotcrete in tunnel design. In addition, existing research has indicated that the growth patterns of the elastic modulus and uniaxial compressive strength of shotcrete during the hardening period are somewhat similar and can be described by relevant formulas.
[0004] In practical engineering applications and design, industry standards such as the "Technical Specification for Rock and Soil Anchors and Shotcrete Support Engineering" (GB50086-2015) and the "Code for Design of Railway Tunnels" (TB10003-2016) provide guidance on the selection of mechanical parameters and engineering design for shotcrete of different grades. For example, TB10003-2016 provides reference values for the compressive strength of C25 shotcrete at 8h and 24h ages.
[0005] However, in current numerical simulation practices for tunnel construction, to simplify calculations, the mechanical properties of shotcrete (such as elastic modulus and compressive strength) are often treated as constant values, directly using its final strength or an empirical average value, while ignoring the dynamic process of these parameters evolving with age. This simplification makes it difficult for numerical simulations to accurately reflect the load-bearing capacity of the initial support in the early stages after construction and its inhibitory effect on surrounding rock deformation, leading to deviations between simulation results and actual engineering conditions, and consequently affecting the rationality and safety of the support structure design.
[0006] Therefore, how to provide a method that can reasonably and meticulously consider the changes in the mechanical properties of shotcrete with age in numerical simulation of tunnel construction has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0007] The purpose of this invention is to provide a numerical simulation method for tunnel construction that considers the spatiotemporal effects of the mechanical properties of support materials. This method addresses the technical problem in existing numerical simulation methods for tunnel construction that simplify the mechanical property parameters of shotcrete to constant values and ignore the "spatiotemporal effects" of their evolution over time, leading to significant deviations between simulation results and actual engineering conditions.
[0008] To achieve the above objectives, this invention provides a numerical simulation method for tunnel construction that considers the spatiotemporal effects of the mechanical properties of support materials, comprising the following steps: S1. Acquisition of age curves of mechanical parameters of support structure materials: Conduct indoor tests and collect field test data to obtain measured data of elastic modulus, Poisson's ratio, and strength of tunnel support structure materials at different ages; use mathematical statistics methods to fit the measured data to obtain the fitting curves of mechanical parameters of support structure materials as a function of age and the corresponding mathematical expressions. S2. Numerical calculation model establishment: Obtain tunnel burial depth, span, height, and excavation method parameters, establish a calculation model using finite element software, apply boundary conditions to the model and assign stratum parameters, and calculate the model until the ground stress balance is reached. S3. Tunnel excavation simulation considering the age-related mechanical parameters of the support structure materials: S31. Obtain the construction process flow for each cycle at the tunnel site and the construction time for each process. S32. Use the FISH function to import the formulas for calculating the strength and elastic modulus of shotcrete; S33. After each excavation cycle is completed, the model is solved to achieve equilibrium, and then support is provided for different sections of the tunnel. S34. Traverse from the tunnel entrance to the working face to determine whether each section is an unsupported section; S35. The elastic modulus of the supported section is updated hourly. The unsupported section is given initial support and strength is applied after the excavation, ventilation and slag removal processes are completed. The strength is updated hourly. S36. A new excavation cycle begins after each cycle ends.
[0009] Preferably, in step S1, the support structure material includes shotcrete, and the mechanical parameters include uniaxial compressive strength, tensile strength, and modulus of elasticity.
[0010] Preferably, in step S1, the age curve of the shotcrete includes a fitted curve of the uniaxial compressive strength as a function of age, with the mathematical expression as follows: ; in, Uniaxial compressive strength, For the final compressive strength, Age period.
[0011] Preferably, in step S1, the relationship between the tensile strength and compressive strength of the shotcrete is as follows: ; in, It is the uniaxial tensile strength. It represents the uniaxial compressive strength.
[0012] Preferably, in step S1, the mathematical expression for the variation of the elastic modulus of shotcrete with age is: ; in, For elastic modulus, For the final elastic modulus, Age period.
[0013] Preferably, in step S2, establishing the calculation model includes: using finite element software to perform three-dimensional modeling, setting different mesh sizes for the surrounding rock and lining structure, and determining the boundary range of the model; The boundary conditions applied include: applying horizontal constraints to the sides of the model, applying vertical constraints to the bottom, and making the top surface a free surface with stress boundaries applied at the top to simulate burial depth conditions; The parameters assigned to the formation include: the surrounding rock adopts the Mohr-Coulomb elastoplastic constitutive model, the initial support adopts solid elements, and the shotcrete is regarded as a rock-like friction material, adopting the Mohr-Coulomb constitutive model.
[0014] Preferably, in step S35, before updating the elastic modulus and strength sequentially by hour, the method further includes: conducting numerical simulation pre-calculation to obtain the calculation steps corresponding to each construction cycle, dividing the obtained calculation steps by the number of hours in each cycle to obtain the calculation steps corresponding to each hour of construction, and establishing a mapping relationship between construction time and calculation steps.
[0015] Preferably, in step S35, updating the elastic modulus and strength sequentially by hour includes: in each excavation cycle, updating the mechanical parameters of the supported section incrementally by hour, and updating the unsupported section after the completion of the process by applying support and starting the timing update. By nesting the evolution law of mechanical parameters over time into the small cycle of each calculation step, the time-varying nature simulation of the mechanical properties of shotcrete is realized.
[0016] Therefore, the present invention employs the above-mentioned numerical simulation method for tunnel construction that considers the spatiotemporal effects of the mechanical properties of support materials, and has the following beneficial effects: (1) Improved the accuracy and realism of numerical simulation.
[0017] By introducing the dynamic evolution law of the mechanical parameters of shotcrete with age, the shortcomings of treating material parameters as constant values in traditional simulations are overcome, making the simulation results closer to the actual stress and deformation state of the surrounding rock and support structure during tunnel construction.
[0018] (2) It has enabled a refined assessment of the early bearing capacity of the support structure.
[0019] The study considers the strength and stiffness growth process of shotcrete within hours to days after application, which can truly reflect the bearing capacity of the initial support in the early stage and its inhibitory effect on the deformation of the surrounding rock, providing a more reliable theoretical basis for the safety evaluation of the support structure.
[0020] (3) It provides a scientific means for optimizing the timing of support and the selection of materials.
[0021] This invention can quantitatively analyze the differences in support effects of different shotcrete types (such as ordinary shotcrete and early high-strength shotcrete) and different types of anchor bolts (such as ordinary anchor bolts and prestressed anchor bolts) at different construction times, providing technical support for the optimal selection of support materials and the optimized design of construction procedures in tunnel engineering.
[0022] (4) It has wide engineering applicability and promotion value.
[0023] The simulation method of this invention is based on general-purpose finite element software (such as FLAC3D) and standardized construction procedure time mapping. The parameters are easy to obtain and the algorithm is simple to implement. It can be applied to tunnel projects with different geological conditions and different excavation methods, and has good prospects for promotion and application.
[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0025] Figure 1 This is a graph showing the variation of uniaxial compressive strength with age in an embodiment of the present invention; Figure 2 This is a fitting curve of uniaxial compressive strength at age according to an embodiment of the present invention; Figure 3 This is a graph showing the relationship between the tensile strength and compressive strength of shotcrete according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the overall model according to an embodiment of the present invention; Figure 5 This is a flowchart of the full-section method construction process according to an embodiment of the present invention; Figure 6 This is a flowchart of the simulation calculation process according to an embodiment of the present invention; Figure 7 This is a schematic diagram illustrating how parameter values change with the excavation process in an embodiment of the present invention; Figure 8 This is a schematic diagram illustrating the change in elastic modulus of shotcrete over time according to an embodiment of the present invention; Figure 9This is a flowchart of the numerical simulation method for tunnel construction that considers the spatiotemporal effects of the mechanical properties of support materials, as per the present invention. Detailed Implementation
[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0027] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0028] Example This embodiment provides a numerical simulation method for tunnel construction that considers the spatiotemporal effects of the mechanical properties of support materials, such as... Figure 9 As shown, it includes the following steps: S1. Obtaining age curves of mechanical parameters of support structure materials: Conduct indoor tests and collect field test data to obtain the changes in elastic modulus, Poisson's ratio, and strength of tunnel support structure materials over time. The specific data on the compressive strength of C30 shotcrete at 2 hours, 4 hours, 6 hours, 8 hours, 24 hours, 3 days, 7 days, and 28 days were plotted as a scatter plot, as shown below. Figure 1 As shown.
[0029] Mathematical statistics methods were used to fit the elastic modulus, Poisson's ratio, and strength curves of the support structure materials under different ages. Based on statistical data, the age curve of the uniaxial compressive strength of shotcrete was fitted, such as... Figure 2 As shown, the age curves and corresponding mathematical expressions of the mechanical parameters of the support structure material are obtained; The support structure material includes shotcrete, and its mechanical parameters include uniaxial compressive strength, tensile strength, and modulus of elasticity.
[0030] The age curve of C30 shotcrete includes a fitted curve of uniaxial compressive strength as a function of age, and the mathematical expression is: ; in, Uniaxial compressive strength, For the final compressive strength, a value of 32~37 MPa can be used. Age period.
[0031] Based on the tensile and compressive strength values of different grades of shotcrete in the "Technical Specification for Rock and Soil Anchors and Shotcrete Support Engineering" (GB50086-2015), a formula for their relationship is fitted, as follows: Figure 3 As shown.
[0032] Based on the fitted curve, the relationship between the tensile strength and compressive strength of C30 shotcrete is obtained: ; in, It is the uniaxial tensile strength. It represents the uniaxial compressive strength.
[0033] The mathematical expression for the variation of the elastic modulus of shotcrete with age is as follows: ; in, For elastic modulus, For the final elastic modulus, this embodiment uses 25 GPa. Age period.
[0034] According to literature review, the Poisson's ratio of shotcrete does not change with age. Based on the "Code for Design of Railway Tunnels" (TB10003-2016), the Poisson's ratio of C30 shotcrete is taken as 0.2.
[0035] S2. Numerical Calculation Model Establishment: Obtain tunnel depth, span, height, and excavation method parameters. Establish a calculation model using finite element software, apply boundary conditions to the model, assign stratum parameters, and calculate the model until stress equilibrium is reached. In this embodiment, the numerical calculation model uses a 300m burial depth and a 50m height; any excess height is replaced by equivalent loads. The tunnel span is 13m, the height is 11m, and the full-face excavation method is selected.
[0036] The establishment of the computational model includes: using Flac3D finite element software for three-dimensional modeling, setting different mesh sizes for the surrounding rock and lining structure, and determining the boundary range of the model; In this embodiment, the mesh size for the surrounding rock and lining structure is 0.5m, the mesh size for the perimeter (one tunnel diameter) is 0.8m, and the mesh size for the remaining surrounding rock is 1m. Considering the boundary constraint effect in the model calculation, the numerical model has dimensions of 100 m × 100 m × 60 m in the X, Y, and Z directions. The upper boundary of the model is 42.9 m from the arch crown, the lower boundary is 44.9 m from the invert, and the left and right boundaries are 50 m from the tunnel centerline. To more completely reflect the evolution of the initial support mechanical properties over time, the excavation direction (Y direction) is 60 m, and the longitudinal mesh width in the excavation direction is 0.75 m. The model generates a total of 392,000 hexahedral mesh elements and 407,511 nodes. The overall model is as follows: Figure 4 As shown.
[0037] The boundary conditions applied include: horizontal constraints applied to the sides of the model, vertical constraints applied to the bottom, and a free surface with stress boundaries applied to the top to simulate burial depth conditions (the top stress boundary is considered based on the self-weight stress field); The formation parameters assigned include: the surrounding rock level is V1, the surrounding rock adopts the Mohr-Coulomb elastoplastic constitutive model, and the surrounding rock parameters are selected as shown in Table 1.
[0038] Table 1 Mechanical parameters of Class V1 surrounding rock
[0039] The initial support uses solid elements and the shotcrete is regarded as a rock-like friction material. The Mohr-Coulomb constitutive model is adopted. The calculation parameters of shotcrete are shown in Table 2.
[0040] Table 2 Mechanical Parameters of Shotcrete
[0041] S3. Tunnel excavation simulation considering the age-related mechanical parameters of the support structure materials: Obtain the construction process flow and construction time of each cycle in the tunnel site. The specific process flow is as follows: Figure 5 As shown in Table 3, the time required for each process is as follows.
[0042] Table 3. Statistics on Excavation and Support Time for Class V Surrounding Rock
[0043] Numerical simulation pre-calculation is conducted to obtain the calculation steps corresponding to each construction cycle by calculating the model to equilibrium. The obtained calculation steps are divided by the number of hours in each cycle to obtain the calculation steps corresponding to each hour of construction.
[0044] According to the pre-calculation, the number of balancing steps required for each cycle model is 1200. Dividing this by 24, we can get that every 50 calculation steps in Flac3D software represents one hour of on-site construction. The FISH function is used to import the formulas for calculating the strength and elastic modulus of shotcrete. Taking the elastic modulus as an example, its value increases rapidly in the early stage. It is assigned and calculated sequentially in each excavation step until the model converges. The time-varying nature of shotcrete is realized by nesting small loops to reflect the evolution of various mechanical parameters over time.
[0045] After each excavation cycle is completed, the model is balanced and then different sections of the tunnel are supported. First, the tunnel is traversed from the tunnel entrance to the working face to determine whether it is an unsupported section. If it is a supported section, its elastic modulus is updated hourly to simulate the age effect of shotcrete in actual tunnel construction. If the section is unsupported, the initial support should be applied and its strength applied after excavation, ventilation, and muck removal are completed, starting 8 hours into the current cycle. The strength is then updated hourly, and a new excavation cycle begins after 24 hours. The simulation flowchart is as follows: Figure 6 As shown in the diagram, the parameter assignment for shotcrete varies with the excavation process. Figure 7 As shown, the final simulation effect is presented in Flac3D software as follows: Figure 8 As shown.
[0046] Example 1 This embodiment uses a tunnel as the engineering background and employs the method of the present invention to conduct numerical simulation of tunnel construction in order to verify the feasibility and technical effect of the method of the present invention.
[0047] 1. Project Overview.
[0048] The tunnel in this embodiment spans from DK252+763 to DK260+790, with a total length of 8027m, a maximum burial depth of 220m, and a design speed of 350km / h. The strata at the tunnel site are mainly mudstone interbedded with sandstone. The excavation method is the full-face method (with invert arch), and the support measures include C30 early high-strength shotcrete and prestressed anchor bolts.
[0049] 2. Numerical model establishment.
[0050] A three-dimensional numerical model is established according to step S2 of this embodiment of the invention. The model is calculated using the finite element software FLAC3D. The model dimensions are X×Y×Z=100m×100m×60m, with the upper boundary 42.9m from the arch crown, the lower boundary 44.9m from the invert, and the left and right boundaries 50m from the tunnel centerline. The mesh size for the surrounding rock and lining structure is 0.5m, the mesh size for the perimeter (one tunnel diameter) is 0.8m, and the mesh size for the remaining surrounding rock is 1m. The longitudinal mesh width in the excavation direction is 0.75m. The model generates a total of 392,000 hexahedral mesh elements, comprising 407,511 nodes.
[0051] Horizontal constraints were applied to the sides of the model, vertical constraints to the bottom, and the top surface was a free surface with an equivalent load applied to simulate a burial depth of 170m. The surrounding rock was modeled using a Mohr-Coulomb elastoplastic constitutive model, with a rock class of IV; specific parameters are shown in Table 4. Initial support used solid elements, and shotcrete used a Mohr-Coulomb constitutive model; parameters are shown in Table 2 of the example.
[0052] Table 4 Mechanical parameters of Class IV surrounding rock
[0053] 3. Obtaining the age parameters of shotcrete.
[0054] According to step S1 of this embodiment of the invention, the mechanical parameters of C30 early high-strength shotcrete at different ages are obtained. Based on the "Railway Tunnel Design Code" (TB10003-2016) and indoor test data, the curve of uniaxial compressive strength of C30 shotcrete with age is fitted. The final compressive strength is taken as 33 MPa, and the change law of elastic modulus with age is close to that of compressive strength. The final elastic modulus is taken as 25 GPa. The mechanical parameter values of C30 shotcrete at different ages are shown in Table 5.
[0055] Table 5 Shotcrete Parameter Table
[0056] 4. Construction process time mapping and dynamic updates.
[0057] According to step S3 of this embodiment of the invention, the construction process flow and the time required for each procedure of each cycle at the tunnel site are obtained, as shown in Table 6. Pre-calculation determines that each construction cycle requires 1200 steps, and the total time for each cycle is 24 hours, resulting in 50 steps per hour.
[0058] Table 6 Correspondence between Construction Time and Calculation Time
[0059] A dynamic update program was written using the FISH language. In each excavation cycle, the elastic modulus and strength parameters of the shotcrete in the supported section were updated sequentially on an hourly basis. For the unsupported section, the support was applied after the process was completed and the timer was started to update, thus realizing the time-varying simulation of the mechanical properties of shotcrete.
[0060] 5. Operating conditions and results analysis.
[0061] To verify the effectiveness of the method of the present invention, seven calculation conditions were set up for comparative analysis, as shown in Table 7.
[0062] Table 7 Simulation Calculation Operating Conditions
[0063] The calculation results of the vertical displacement of the arch crown under each working condition are shown in Table 8.
[0064] Table 8 Comparison of Vertical Displacement of Arch Crown under Various Working Conditions
[0065] 6. Verification of technical effectiveness.
[0066] As can be seen from Table 8: (1) Compared with ordinary shotcrete (condition 2), the reduction ratio of arch displacement by early high-strength shotcrete (condition 3) increased from 30.8% to 44.0%, indicating that early high-strength shotcrete can exert its bearing capacity earlier and more effectively limit the deformation of the surrounding rock due to its higher early strength.
[0067] (2) Compared with ordinary anchors (condition 4), the reduction ratio of arch displacement by using prestressed anchors (condition 5) increased from 22.5% to 39.8%, indicating that the prestressed anchors can compress the loose surface rock mass by applying prestress, thereby improving the self-supporting capacity of the surrounding rock.
[0068] (3) Compared with ordinary support (condition 6), the active support (condition 7: prestressed anchor bolts + early high-strength shotcrete) reduced the arch displacement by 46.4% to 52.6%, and the support effect was the best.
[0069] This embodiment demonstrates that the method of the present invention can accurately simulate the dynamic evolution of the mechanical properties of shotcrete over time, truly reflecting the control effect of different support materials and different support timing on the deformation of the surrounding rock, and providing a reliable basis for the optimized design of tunnel support structures.
[0070] Therefore, the present invention employs the above-mentioned numerical simulation method for tunnel construction that considers the spatiotemporal effects of the mechanical properties of support materials, and has the following beneficial effects: (1) Improved the accuracy and realism of numerical simulation.
[0071] By introducing the dynamic evolution law of the mechanical parameters of shotcrete with age, the shortcomings of treating material parameters as constant values in traditional simulations are overcome, making the simulation results closer to the actual stress and deformation state of the surrounding rock and support structure during tunnel construction.
[0072] (2) It has enabled a refined assessment of the early bearing capacity of the support structure.
[0073] The study considers the strength and stiffness growth process of shotcrete within hours to days after application, which can truly reflect the bearing capacity of the initial support in the early stage and its inhibitory effect on the deformation of the surrounding rock, providing a more reliable theoretical basis for the safety evaluation of the support structure.
[0074] (3) It provides a scientific means for optimizing the timing of support and the selection of materials.
[0075] This invention can quantitatively analyze the differences in support effects of different shotcrete types (such as ordinary shotcrete and early high-strength shotcrete) and different types of anchor bolts (such as ordinary anchor bolts and prestressed anchor bolts) at different construction times, providing technical support for the optimal selection of support materials and the optimized design of construction procedures in tunnel engineering.
[0076] (4) It has wide engineering applicability and promotion value.
[0077] The simulation method of this invention is based on general-purpose finite element software (such as FLAC3D) and standardized construction procedure time mapping. The parameters are easy to obtain and the algorithm is simple to implement. It can be applied to tunnel projects with different geological conditions and different excavation methods, and has good prospects for promotion and application.
[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials, characterized in that, Includes the following steps: S1. Acquisition of age curves of mechanical parameters of support structure materials: Conduct indoor tests and collect field test data to obtain measured data of elastic modulus, Poisson's ratio, and strength of tunnel support structure materials at different ages; use mathematical statistics methods to fit the measured data to obtain the fitting curves of mechanical parameters of support structure materials as a function of age and the corresponding mathematical expressions. S2. Numerical calculation model establishment: Obtain tunnel burial depth, span, height, and excavation method parameters, establish a calculation model using finite element software, apply boundary conditions to the model and assign stratum parameters, and calculate the model until the ground stress balance is reached. S3. Tunnel excavation simulation considering the age-related mechanical parameters of the support structure materials: S31. Obtain the construction process flow for each cycle at the tunnel site and the construction time for each process. S32. Use the FISH function to import the formulas for calculating the strength and elastic modulus of shotcrete; S33. After each excavation cycle is completed, the model is solved to achieve equilibrium, and then support is provided for different sections of the tunnel. S34. Traverse from the tunnel entrance to the working face to determine whether each section is an unsupported section; S35. The elastic modulus of the supported section is updated hourly. The unsupported section is given initial support and strength is applied after the excavation, ventilation and slag removal processes are completed. The strength is updated hourly. S36. A new excavation cycle begins after each cycle ends.
2. The numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials according to claim 1, characterized in that, In step S1, the support structure material includes shotcrete, and the mechanical parameters include uniaxial compressive strength, tensile strength, and modulus of elasticity.
3. The numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials according to claim 2, characterized in that, In step S1, the age curve of the shotcrete includes a fitted curve of the uniaxial compressive strength changing with age, and the mathematical expression is: ； in, Uniaxial compressive strength, For the final compressive strength, Age period.
4. The numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials according to claim 2, characterized in that, In step S1, the relationship between the tensile strength and compressive strength of shotcrete is as follows: ； in, It is the uniaxial tensile strength. It represents the uniaxial compressive strength.
5. The numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials according to claim 2, characterized in that, In step S1, the mathematical expression for the variation of the elastic modulus of shotcrete with age is: ； in, For elastic modulus, For the final elastic modulus, Age period.
6. The numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials according to claim 1, characterized in that, In step S2, establishing the calculation model includes: using finite element software to perform three-dimensional modeling, setting different mesh sizes for the surrounding rock and lining structure, and determining the boundary range of the model; The boundary conditions applied include: applying horizontal constraints to the sides of the model, applying vertical constraints to the bottom, and making the top surface a free surface with stress boundaries applied at the top to simulate burial depth conditions; The parameters assigned to the formation include: the surrounding rock adopts the Mohr-Coulomb elastoplastic constitutive model, the initial support adopts solid elements, and the shotcrete is regarded as a rock-like friction material, adopting the Mohr-Coulomb constitutive model.
7. The numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials according to claim 1, characterized in that, In step S35, before updating the elastic modulus and strength sequentially by hour, the following steps are also included: conducting numerical simulation pre-calculation to obtain the calculation steps corresponding to each construction cycle, dividing the obtained calculation steps by the number of hours in each cycle to obtain the calculation steps corresponding to each hour of construction, and establishing a mapping relationship between construction time and calculation steps.
8. The numerical simulation method for tunnel construction considering the spatiotemporal effects of the mechanical properties of support materials according to claim 1, characterized in that, In step S35, updating the elastic modulus and strength sequentially by hour includes: in each excavation cycle, updating the mechanical parameters of the supported section incrementally by hour, and updating the unsupported section after the completion of the process by applying support and starting the timing update. By nesting the evolution law of mechanical parameters over time into the small cycle of each calculation step, the time-varying nature simulation of the mechanical properties of shotcrete is realized.