Deeply-buried tunnel support design method considering rock mass dynamic damage

Abstract

The invention relates to a deep tunnel support design method considering rock mass dynamic damage, which comprises the following steps: acquiring and dynamically updating rock mass in-situ mechanical parameters, engineering parameters and the like of a tunnel excavation surface in a strong earthquake region, and calculating to obtain rock mass dynamic damage and strength parameters by combining a GZZ three-dimensional dynamic strength theory; the method comprises the following steps: simulating a total stress-strain response process of surrounding rock under the action of three-dimensional static-dynamic coupling disturbance in a tunnel excavation process by introducing damage parameters of a dynamic disturbance rock mass and adopting a deep tunnel excavation static-dynamic coupling three-dimensional numerical model and a dynamic three-dimensional strength criterion; a stress control method is provided from two angles of dynamic force and static force to improve the stress state of a rock mass, so that the positive analysis support design of the deep tunnel under the conditions of blasting construction, strong earthquake or rock burst and the like is realized, and active control measures are adopted to realize active control of the stability of the surrounding rock of the deep tunnel in the strong earthquake area. Compared with the prior art, the method has the advantages that reliability and scientificity of dynamic analysis and support design of the deep tunnel rock mass in the strong earthquake area are improved, and the like.

Description

Technical Field

[0001] The invention relates to the field of tunnel static-dynamic coupling numerical simulation analysis, and in particular to a deep-buried tunnel support design method taking into account rock mass dynamic damage. Background Art

[0002] With the vigorous construction of deep buried tunnels, it is inevitable to cross active fault zones and their affected areas. The dynamic disturbances caused by earthquakes, blasting, rock bursts and vibration excavation are prone to dynamic damage to the rock mass. After the rock mass is subjected to dynamic disturbances, its mechanical properties will be affected to varying degrees, resulting in a large difference between the static-dynamic coupling mechanical response characteristics of the rock mass after tunnel excavation and the static mechanical response characteristics, which in turn makes the excavation construction and support design methods of deep buried tunnels different. In the past, scholars used rock theory for static problems and numerical calculations of static excavation for research and analysis before design. However, they lacked consideration of the various dynamic damages suffered by the rock mass in actual tunnel engineering, especially the dynamic disturbances such as strong earthquakes, rock bursts and blasting vibrations that are often encountered in active fault zones. This makes the positive analysis results obtained by the existing numerical calculations differ from the on-site monitoring data by multiples or even orders of magnitude. The design and construction personnel cannot use the numerical calculation results to directly guide the actual project, and it is difficult to accurately predict the various disasters caused by dynamic disturbances in the actual project. Therefore, it is necessary to establish a static-dynamic coupled three-dimensional numerical calculation method for deep tunnel excavation considering the dynamic damage of rock mass, so as to accurately analyze the dynamic disturbance problem of deep tunnel excavation and propose a support design method for precise control of rock mass stress in deep tunnel. Summary of the invention

[0003] The purpose of the present invention is to provide a deep buried tunnel support design method considering rock mass dynamic damage, so as to provide direct guidance for deep buried tunnel practical engineering and predict the disasters caused by dynamic damage. To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0004] A deep tunnel support design method considering rock mass dynamic damage includes the following steps:

[0005] Step 1: Use digital in-situ testing methods of deep tunnel three-dimensional geology and excavation face rock mass to obtain and dynamically update tunnel in-situ mechanical parameters and engineering parameters in real time, and determine rock mass dynamic damage and strength parameters based on this. The specific determination method is shown in step 2-1; the tunnel in-situ mechanical parameters mainly include geological strength index (GSI), ground stress of strata, rock mass strain softening coefficient, rock mass dynamic damage factor (rock mass damage caused by strong earthquakes, blasting, vibration, rock bursts, etc.) and rock mass physical parameters (density, water content, elastic modulus, Poisson's ratio, rock hardness), etc. The engineering parameters include tunnel excavation area, support structure design parameters, construction excavation footage and step length, etc.

[0006] Step 2: Using the rock mass dynamic three-dimensional strength criterion, based on the in-situ mechanical parameters and engineering parameters in step 1, a static-dynamic coupled three-dimensional numerical model of deep tunnel excavation is established, and numerical simulation excavation is performed according to the full-section or partial excavation method of on-site blasting or mechanical excavation, and the deformation and force data and material damage status of key surrounding rock sections and support structures are extracted;

[0007] Step 2-1: Use the three-dimensional dynamic strength criterion of rock mass to analyze the static-dynamic coupling three-dimensional numerical model of deep tunnel excavation; the dynamic damage and strength parameter calculation formulas for the three-dimensional dynamic strength criterion of rock mass are as follows:

[0008]

[0009] Among them, m b , s, a are the dynamic damage and strength parameters of rock mass, m i Represents the hardness of the rock. It is an indicator of geological strength under dynamic action. It is the dynamic disturbance coefficient caused by strong earthquakes, blasting, vibration, rock burst, etc.

[0010] Calculation method: Based on the vibration waveform time history curve monitored on site, it is converted into strain rate, and then the strain rate is calculated Next The formula is as follows:

[0011]

[0012] in, It can be obtained by fitting the dynamic test of indoor rock samples. The calculation method and Consistent.

[0013] The rock mass in the three-dimensional numerical model is established using the dynamic three-dimensional strength criterion, which is as follows:

[0014]

[0015] Where I1, J2 and J3 are the first stress invariant, the second deviator stress invariant and the third deviator stress invariant, respectively. is the dynamic uniaxial compressive strength,

[0016] Acquisition method: Collect rock samples on site and make standard uniaxial compressive strength specimens. Set different loading strain rates to obtain the dynamic uniaxial compressive strength of rock.

[0017] Step 2-2: Determine the equivalent rock mass dynamic cohesion c and equivalent rock mass dynamic internal friction angle based on the rock mass dynamic damage and strength parameters obtained from in-situ tests and indoor tests.

[0018]

[0019] In the formula, σ 3max is the maximum confining pressure; 3max and rock mass strength σ cm The calculation method is:

[0020]

[0021] In the formula, γ is the gravity, H is the burial depth, γ i and h i are the overlying rock mass and rock thickness, respectively;

[0022] Step 2-3: The boundary of the three-dimensional numerical model is set according to the magnitude of the formation stress, and the maximum principal stress lateral pressure coefficient and the minimum principal stress lateral pressure coefficient are set to λ Hv and λ hv ,Right now:

[0023]

[0024] In the formula, σ v is the vertical stress, σ H is the maximum horizontal stress, σ h is the minimum horizontal stress, θ Hy is the angle between the longitudinal axis of the tunnel and the direction of maximum principal stress;

[0025] Step 2-4: Perform large-scale three-dimensional static-dynamic coupling numerical calculations of deep-buried tunnels in full-section or partial excavation methods using on-site blasting or mechanical excavation to obtain displacement cloud maps, stress cloud maps, and damage cloud maps of key surrounding rock sections, thereby extracting deformation and force data and material damage status of key surrounding rock sections and support structure monitoring points.

[0026] Step 3: Extract the three-dimensional numerical calculation results of static-dynamic coupling of deep tunnel excavation, such as stress, displacement, elastoplastic state, etc. of key units, calculate the dynamic damage value of rock mass (dynamic damage size of rock mass), the evolution of principal stress of key rock mass units (principal stress value of key rock mass units) with the excavation steps, and evaluate the influence of dynamic damage on rock mass deformation and stress; and calculate the influence of dynamic damage on the principal stress size, strength and failure mode of rock mass in combination with three-dimensional spatial effect, and clarify the influence of dynamic damage on the rotation of stress principal axis;

[0027] Step 3-1: Use the three-dimensional rock mass dynamic strength criterion to perform static calculations on the numerical model. The dynamic geological strength index is used for dynamics. and the dynamic disturbance coefficient Calculate the dynamic response of rock mass caused by strong earthquake, blasting, vibration, rock burst, etc., where the strain rate Derived from the vibration waveform curve of on-site dynamic monitoring;

[0028] Step 3-2, extract the principal stress value of the key rock mass unit and the dynamic damage value of the rock mass in each excavation step, and evaluate the influence of the dynamic damage on the deformation and stress of the rock mass;

[0029] The principal stress values ​​of key rock mass units are calculated as follows:

[0030]

[0031] Where σ is the first, second or third principal stress, σ i (i=x,y,z) is the normal stress in the i direction of the key rock mass unit directly extracted from the numerical calculation results, τ ij (ij=xy,yx,xz,zx,yz,zy) is the shear stress in the ij direction of the key rock unit directly extracted from the numerical calculation results, and l, m and n are the cosine values ​​of the angles between the principal stress and the x, y and z directions, respectively.

[0032] The dynamic damage value d of the rock mass is calculated as follows: The dynamic damage of the rock mass here refers specifically to the damage caused by dynamic disturbance of the rock mass. Assuming that the damage value before excavation is d = 0, and the damage value after damage occurs is d = 1, after the rock mass reaches the dynamic strength and enters plasticity, the damage accumulates continuously inside it. The calculation formula is as follows:

[0033]

[0034] in, is the dynamic disturbance (i.e., strain rate The first principal stress of the rock mass yielding under the condition of action) is assumed to be For static effect.

[0035] Step 3-3, by drawing the curve of the dynamic damage value of the key rock mass unit changing with the excavation step, the three-dimensional spatial effect of the dynamic disturbance on the tunnel surrounding rock is obtained, and then the influence of the dynamic damage on the principal stress, strength and failure mode of the rock mass is calculated to clarify the influence of the dynamic damage on the rotation of the stress principal axis. The influence of dynamic damage on the principal stress, strength and failure mode of the rock mass and the influence of dynamic damage on the rotation of the stress principal axis include:

[0036] (1) The rock mass is in a state of stress equilibrium before excavation. During and after excavation, it will show different response characteristics from those under static conditions due to dynamic disturbances such as blasting, rock burst or earthquake, resulting in changes in stress state, including stress magnitude and direction. The structural plane in the rock mass will weaken the strength of the rock mass due to dynamic disturbances, making the rock mass more easily damaged, causing new cracks to continuously form inside the rock mass, and the existing cracks to continuously expand and penetrate until they are damaged, thereby greatly reducing the dynamic strength of the rock mass, which is manifested in the numerical simulation as a reduction in the stress magnitude of the rock mass unit.

[0037] (2) Due to the expansion and penetration of cracks inside the rock mass under dynamic disturbance, the stress path inside the rock mass will also change, causing the stress principal axis of the rock unit to change continuously. In the numerical calculation results, this is manifested as a rotation of the stress principal axis, which ultimately causes the rock mass failure mode to be converted to dynamic disturbance failure, which is actually manifested as a higher degree of fragmentation after the rock mass is destroyed.

[0038] Step 4: Based on step 3, clarify the damage stress changes caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress; based on the damage stress changes caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress, propose two stress control methods: construction measures of "reducing dynamic disturbance" and support optimization design of "stress transfer and compensation", so as to improve the bearing capacity of the rock mass itself and prevent disasters such as rock burst and large deformation. The specific steps are as follows:

[0039] Step 4-1: The dynamic disturbance of the tunnel causes different degrees of damage to the rock mass. The principal stress changes of the surrounding rock and the changes of the damaged area caused by the dynamic damage of the rock mass are obtained through the static-dynamic coupling three-dimensional numerical calculation of the deep tunnel excavation.

[0040] Step 4-2: Compare the calculation results with those of the static excavation numerical model to calculate the influence range and degree of dynamic damage on the stress and strain of the surrounding rock; the static excavation model is the strain rate Three-dimensional numerical model of a deep buried tunnel.

[0041] Step 4-3: Based on the changes in damage stress caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress, construction measures of “reducing dynamic disturbance” are proposed. At the same time, support optimization design of “stress transfer and compensation” is adopted to improve the bearing capacity of the rock mass itself, and the design is substituted into the numerical model for calculation and verification of its effectiveness.

[0042] Step 5: Use the stress control method of construction measures and support design optimization in step 4 to actively control the rock mass disasters caused by dynamic disturbances in deep buried tunnels. Construction measures include smooth blasting control, over-break and under-break control, multi-step excavation and partial excavation, etc.; design optimization includes advanced grouting at the top of the face, advanced core rock reinforcement, targeted anchor bolting, and pressure-yielding support.

[0043] The step 5) adopts a variety of active control methods to prevent rock disasters caused by dynamic disturbances in deep tunnels. The construction measures of "reducing dynamic disturbances" include smooth blasting parameter control, over-excavation and under-excavation control, multi-step excavation and partial excavation, etc.; the support design optimization of "stress transfer and compensation" includes the advance grouting range at the top of the face, the strength and range of the advanced core rock reinforcement, the type and depth of the targeted anchor rods, and the use of radial or annular pressure-yielding support. The core of active control of surrounding rock is to transform the rock mass from an unstable state to a stable state, especially to make the rock mass within the failure surface of the three-dimensional dynamic strength under dynamic disturbance, so that the rock mass does not suffer sudden dynamic damage.

[0044] Furthermore, the rock mass dynamic damage is determined by the strain rate caused by one or more of strong earthquakes, blasting, vibrations, and rockbursts.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The present invention uses digital in-situ testing to quickly acquire and update in-situ mechanical parameters and engineering parameters in real time, especially the direct acquisition of on-site dynamic parameters, which are converted into strain rates and directly input into the numerical model for calculation, so that various on-site dynamic disturbances can be analyzed.

[0047] (2) The present invention adopts the dynamic three-dimensional strength criterion (DGZZ) to establish a three-dimensional numerical model of a deep buried tunnel considering the dynamic damage of the rock mass, and analyzes the deformation and stress data and material damage status of the key surrounding rock sections and support structures.

[0048] (3) The present invention evaluates the influence of dynamic damage on rock deformation and stress by calculating the magnitude of dynamic damage to the rock mass and the evolution of principal stress of key rock mass units with excavation steps; and combines the three-dimensional spatial effect to calculate the influence of dynamic damage on the magnitude, strength and failure mode of principal stress of the rock mass, and clarifies the influence of dynamic damage on the rotation of the stress principal axis.

[0049] (4) The present invention proposes the construction measure of "reducing dynamic disturbance" and adopts the support optimization design of "stress transfer and compensation" to improve the bearing capacity of the rock mass itself and prevent disasters such as rock bursts and large deformations.

[0050] (5) The present invention truly considers the static-dynamic coupled mechanical response characteristics of the unloaded rock mass during deep tunnel excavation under high stress and dynamic disturbance, and realizes a more comprehensive and realistic numerical simulation and analysis of deep tunnel engineering, thereby obtaining reliable analysis results and guiding the active control of deep tunnels, greatly improving the safety and scientificity of construction excavation and support design. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0052] Figure 2 A schematic diagram of a three-dimensional finite element numerical model of a deep-buried tunnel considering the three-dimensional dynamic strength criterion of rock mass according to an embodiment of the present invention;

[0053] Figure 3 A schematic diagram of a deep tunnel construction improvement measure according to an embodiment of the present invention;

[0054] Figure 4 Schematic diagram of optimization measures for the design of compression support for deep buried tunnels according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments. The features such as component models, material names, connection structures, control methods, etc. that are not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0056] The present invention relates to a deep buried tunnel support design method considering rock mass dynamic damage, including: obtaining and dynamically updating in-situ mechanical parameters and engineering parameters of rock mass on tunnel excavation face in strong earthquake zone, combining GZZ three-dimensional dynamic strength theory to calculate rock mass dynamic damage and strength parameters; by introducing damage parameters of dynamically disturbed rock mass, using deep buried tunnel excavation static-dynamic coupling three-dimensional numerical model and dynamic three-dimensional strength criterion, simulating the full stress-strain response process of surrounding rock under three-dimensional static-dynamic coupling disturbance during tunnel excavation; proposing stress control methods from two perspectives, dynamic and static, to improve rock mass stress state, thereby realizing positive analysis support design of deep buried tunnel under conditions of blasting construction, strong earthquake or rock burst, and using active control measures to realize active control of surrounding rock stability of deep buried tunnel in strong earthquake zone. Compared with the prior art, the present invention has the advantages of improving the reliability and scientificity of rock mass dynamic analysis and support design of deep buried tunnel in strong earthquake zone.

[0057] Example

[0058] This embodiment provides a deep tunnel support design method considering rock mass dynamic damage. Figure 1As shown, the following steps are included:

[0059] Step 1: Use digital in-situ testing methods of deep tunnel three-dimensional geology and excavation face rock mass to obtain and dynamically update tunnel in-situ mechanical parameters and engineering parameters in real time, and determine rock mass dynamic damage and strength parameters. The specific determination method is shown in step 2-1; the tunnel in-situ mechanical parameters mainly include geological strength index (GSI), ground stress of strata, rock mass strain softening coefficient, rock mass dynamic damage factor (rock mass damage caused by strong earthquakes, blasting, vibration, rock bursts, etc.) and rock mass physical parameters (density, water content, elastic modulus, Poisson's ratio, hardness and softness), etc. The engineering parameters include tunnel excavation area, support structure design parameters, construction excavation footage and step length, etc.

[0060] In this embodiment, the in-situ mechanical parameters of a tunnel mainly include the geological strength index GSI, the ground stress p of the stratum, the rock mass strain softening coefficient, the rock mass dynamic damage factor d (rock mass damage caused by strong earthquakes, blasting, vibration, rock bursts, etc.) and the rock mass physical parameters (density ρ, water content w, elastic modulus E, Poisson's ratio ν, hardness m i ). The engineering parameters include tunnel excavation area A, support structure design parameters (lining thickness, anchor length, etc.), construction excavation footage and step length, etc.

[0061] Specifically, after each cycle of excavation, the face rock mass is photographed at 8 different angles to record the rock mass image information, and the characteristic information such as the trace, number of groups, occurrence and distribution of the rock mass structure surface is extracted through the image information. Then the rock mass structure surface is reconstructed in three dimensions to obtain the static GSI parameters; obtain in-situ ground stress p through micro-fracturing test; obtain rock elastic modulus E through Schmidt hammer test; collect rock samples and make standard uniaxial compressive strength specimens to obtain rock uniaxial compressive strength σ c ; Simultaneously measure density ρ, moisture content w, Poisson's ratio ν and hardness m i etc.; select a reasonable initial value d of the dynamic damage factor according to the excavation method used on site, such as blasting, mechanical excavation, etc. The engineering parameters are selected according to the actual construction plan and design drawings.

[0062] Step 2: adopt the rock mass dynamic three-dimensional strength criterion, establish a static-dynamic coupled three-dimensional numerical model of deep tunnel excavation based on the in-situ mechanical parameters and engineering parameters in step 1, perform numerical simulation excavation in full section or partial excavation mode of on-site blasting or mechanical excavation, and extract deformation and stress data and material damage status of key surrounding rock sections and support structures; Step 2 specifically includes:

[0063] Step 2-1: Use the three-dimensional dynamic strength criterion of rock mass to analyze the static-dynamic coupling three-dimensional numerical model of deep tunnel excavation; the dynamic damage and strength parameter calculation formulas for the three-dimensional dynamic strength criterion of rock mass are as follows:

[0064]

[0065] Among them, m b , s, a are rock mass damage and dynamic strength parameters, m i Represents the hardness of the rock. It is an indicator of geological strength under dynamic action. It is the dynamic disturbance coefficient caused by strong earthquakes, blasting, vibration, rock burst, etc.

[0066] Calculation method: Based on the vibration waveform time history curve monitored on site, it is converted into strain rate and then the strain rate is calculated. Next The formula is as follows:

[0067]

[0068] in, It can be obtained by fitting the dynamic test of indoor rock samples. The calculation method and Consistent.

[0069] The rock mass in the three-dimensional numerical model is established using the dynamic three-dimensional strength criterion, which is as follows:

[0070]

[0071] Where I1, J2 and J3 are the first stress invariant, the second deviator stress invariant and the third deviator stress invariant, respectively. is the dynamic uniaxial compressive strength,

[0072] Acquisition method: Collect rock samples on site and make standard uniaxial compressive strength specimens. Set different loading strain rates to obtain the dynamic uniaxial compressive strength of rock.

[0073] Step 2-2: Determine the equivalent rock mass dynamic cohesion c and equivalent rock mass dynamic internal friction angle based on the rock mass dynamic strength parameters obtained from in-situ tests and indoor tests.

[0074]

[0075] In the formula, σ 3max is the maximum confining pressure;3max and rock mass strength σ cm The calculation method is:

[0076]

[0077] In the formula, γ is the gravity, H is the burial depth, γ i and h i are the overlying rock mass and rock thickness, respectively;

[0078] Step 2-3: The boundary of the three-dimensional numerical model is set according to the magnitude of the formation stress, and the maximum principal stress lateral pressure coefficient and the minimum principal stress lateral pressure coefficient are set to λ Hv and λ hv ,Right now:

[0079]

[0080] In the formula, σ v is the vertical stress, σ H is the maximum horizontal stress, σ h is the minimum horizontal stress, θ Hy is the angle between the longitudinal axis of the tunnel and the direction of maximum principal stress;

[0081] Step 2-4: Perform large-scale three-dimensional static-dynamic coupling numerical calculations of deep-buried tunnels in full-section or partial excavation methods using on-site blasting or mechanical excavation to obtain displacement cloud maps, stress cloud maps, and damage cloud maps of key surrounding rock sections, thereby extracting deformation and force data and material damage status of key surrounding rock sections and support structure monitoring points.

[0082] Step 3: Extract the three-dimensional numerical calculation results of static-dynamic coupling of deep tunnel excavation, such as stress, displacement, elastoplastic state, etc. of key units, calculate the dynamic damage value of rock mass (dynamic damage size of rock mass), the evolution of principal stress of key rock mass units (principal stress value of key rock mass units) with the excavation step, and evaluate the influence of dynamic damage on rock mass deformation and stress; and calculate the influence of dynamic damage on the principal stress size, strength and failure mode of rock mass in combination with three-dimensional spatial effect, and clarify the influence of dynamic damage on the rotation of stress principal axis; Step 3 specifically includes:

[0083] Step 3-1: Use the three-dimensional rock mass dynamic strength criterion to perform static calculations on the numerical model. The dynamic geological strength index is used for dynamics. and the dynamic disturbance coefficient Calculate the dynamic response of rock mass caused by strong earthquake, blasting, vibration, rock burst, etc., where the strain rate Derived from the vibration waveform curve of on-site dynamic monitoring;

[0084] Step 3-2, extract the principal stress value of the key rock mass unit and the dynamic damage value of the rock mass in each excavation step, and evaluate the influence of the dynamic damage on the deformation and stress of the rock mass;

[0085] The principal stress values ​​of key rock mass units are calculated as follows:

[0086]

[0087] Where σ is the first, second or third principal stress, σ i (i=x,y,z) is the normal stress in the i direction of the key rock mass unit directly extracted from the numerical calculation results, τ ij (ij=xy,yx,xz,zx,yz,zy) is the shear stress in the ij direction of the key rock unit directly extracted from the numerical calculation results, and l, m and n are the cosine values ​​of the angles between the principal stress and the x, y and z directions, respectively.

[0088] The dynamic damage value d of the rock mass is calculated as follows: The dynamic damage of the rock mass here refers specifically to the damage caused by dynamic disturbance of the rock mass. Assuming that the damage value before excavation is d = 0, and the damage value after damage occurs is d = 1, after the rock mass reaches the dynamic strength and enters plasticity, the damage accumulates continuously inside it. The calculation formula is as follows:

[0089]

[0090] in, is the dynamic disturbance (i.e., strain rate The first principal stress of the rock mass yielding under the condition of action) is assumed to be For static effect.

[0091] Step 3-3: By plotting the dynamic damage value of the key rock mass unit as the excavation step changes, the three-dimensional spatial effect of the dynamic disturbance on the tunnel surrounding rock is obtained, and then the influence of the dynamic damage on the principal stress, strength and failure mode of the rock mass is calculated to clarify the influence of the dynamic damage on the rotation of the stress principal axis.

[0092] Step 4: Based on step 3, clarify the damage stress changes caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress; based on the damage stress changes caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress, propose two stress control methods: construction measures of "reducing dynamic disturbance" and support optimization design of "stress transfer and compensation", so as to improve the bearing capacity of the rock mass itself and prevent disasters such as rock burst and large deformation. The specific steps are as follows:

[0093] Step 4-1: The dynamic disturbance of the tunnel causes different degrees of damage to the rock mass. The principal stress changes of the surrounding rock and the changes of the damaged area caused by the dynamic damage of the rock mass are obtained through the static-dynamic coupling three-dimensional numerical calculation of the deep tunnel excavation.

[0094] Step 4-2: Compare the calculation results with those of the static excavation numerical model to calculate the influence range and degree of dynamic damage on the stress and strain of the surrounding rock; the static excavation model is the strain rate Three-dimensional numerical model of a deep buried tunnel.

[0095] Step 4-3: Based on the changes in damage stress caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress, construction measures of “reducing dynamic disturbance” are proposed. At the same time, support optimization design of “stress transfer and compensation” is adopted to improve the bearing capacity of the rock mass itself, and the design is substituted into the numerical model for calculation and verification of its effectiveness.

[0096] Step 5: Use the construction measures and design optimization stress control method in step 4 to actively control the rock mass damage caused by the dynamic disturbance of the deep buried tunnel. The construction measures include smooth blasting control, over-excavation control, multi-step excavation and partial excavation, etc. Figure 3 As shown in the figure, the optimization is achieved through the optimization of the upper step area construction, the optimization of the reserved upper step core soil, the optimization of the upper step step shortening, and the blasting control of the middle step excavation; the design optimization includes advanced grouting at the top of the tunnel face, advanced core rock reinforcement, targeted anchoring, and the use of yielding support. The schematic diagram of yielding support design is shown in the figure. Figure 4 shown.

[0097] The step 5) adopts a variety of active control methods to prevent rock disasters caused by dynamic disturbances in deep tunnels. Construction measures include smooth blasting parameter control, over-excavation and under-excavation control, multi-step excavation and partial excavation, etc.; design optimization includes the scope of advance grouting at the top of the face, the strength and scope of advance core rock reinforcement, the type and depth of targeted anchors, and the use of radial or annular pressure-yielding support. The core of active control of surrounding rock is to transform the rock mass from an unstable state to a stable state, especially to make the rock mass within the failure surface of the three-dimensional dynamic strength under dynamic disturbance, so that the rock mass does not suffer sudden dynamic damage.

[0098] The three-dimensional dynamic strength criterion suitable for deep rock mass dynamic analysis, the three-dimensional numerical simulation method for tunnel excavation considering static-dynamic coupling, and the implementation parameter selection method based on digital in-situ testing established and proposed in the present invention provide a reliable theoretical basis for the accurate analysis of the dynamic response characteristics of rock mass excavation in deep tunnel engineering.

[0099] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning, or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A deep tunnel support design method considering rock mass dynamic damage, characterized in that: The following steps are involved: Step 1), using digital in-situ testing methods of deep-buried tunnel three-dimensional geology and excavation face rock mass, real-time acquisition and dynamic update of tunnel in-situ mechanical parameters and engineering parameters, and determining rock mass dynamic damage and strength parameters based on the tunnel in-situ mechanical parameters and engineering parameters; Step 2) adopting the rock mass dynamic three-dimensional strength criterion, based on the in-situ mechanical parameters and engineering parameters, a static-dynamic coupled three-dimensional numerical model of deep tunnel excavation is established, and numerical simulation excavation is performed according to the full section or partial excavation method of on-site blasting or mechanical excavation, and the deformation and force data and material damage status of the key surrounding rock sections and support structures are extracted; Step 3), extracting the static-dynamic coupling three-dimensional numerical calculation results of deep tunnel excavation, the static-dynamic coupling three-dimensional numerical calculation results of deep tunnel excavation include stress, displacement, and elastic-plastic state of key units, calculating the magnitude of dynamic damage to the rock mass, the evolution of the principal stress of the rock mass unit at the key monitoring point with the excavation step, and evaluating the influence of dynamic damage on the deformation and stress of the rock mass; and combining the three-dimensional spatial effect, calculating the influence of dynamic damage on the principal stress magnitude, strength and failure mode of the rock mass, and clarifying the influence of dynamic damage on the rotation of the stress principal axis; Step 4) Based on step 3), the damage stress changes caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress are clarified; based on the damage stress changes caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress, two stress control methods are proposed, namely, the construction measures of "reducing dynamic disturbance" and the support optimization design of "stress transfer and compensation", so as to improve the bearing capacity of the rock mass itself; Step 5) adopts the stress control method of optimizing the construction measures and support design in step 4) to actively control the rock mass disasters caused by the dynamic disturbance of the deep buried tunnel.

2. A deep tunnel support design method considering rock mass dynamic damage according to claim 1, characterized in that: The construction measures include smooth blasting control, over-break and under-break control, multi-step excavation and partial excavation; The design optimization includes advance grouting at the top of the face, advance core rock reinforcement, targeted anchoring, and pressure-yielding support.

3. A deep tunnel support design method considering rock mass dynamic damage according to claim 1, characterized in that: The tunnel in-situ mechanical parameters include geological strength index, ground stress of strata, rock mass strain softening coefficient, rock mass dynamic damage factor and rock mass physical parameters; The rock mass physical parameters include the hardness and softness of the rock; The engineering parameters include tunnel excavation area, support structure design parameters, construction excavation progress and step length.

4. A deep tunnel support design method considering rock mass dynamic damage according to claim 1, characterized in that: The rock mass dynamic damage is determined by the strain rate caused by one or more of strong earthquakes, explosions, vibrations, and rock bursts.

5. The deep tunnel support design method considering rock mass dynamic damage according to claim 1 is characterized in that: The static-dynamic coupled three-dimensional numerical model analysis of deep tunnel excavation is carried out based on the three-dimensional dynamic strength criterion of rock mass. The calculation formulas of dynamic damage and strength parameters for the three-dimensional dynamic strength criterion of rock mass are as follows: In the formula, m b , s, a are the dynamic damage and strength parameters of rock mass, m i Represents the hardness of the rock. It is an indicator of geological strength under dynamic action. It is the dynamic disturbance coefficient caused by strong earthquakes, blasting, vibration, and rock burst.

6. A deep tunnel support design method considering rock mass dynamic damage according to claim 1, characterized in that: The step 2) comprises: 2-1) The rock mass in the three-dimensional numerical model is established using the dynamic three-dimensional strength criterion, which is as follows: Where I1, J2 and J3 are the first stress invariant, the second deviator stress invariant and the third deviator stress invariant, respectively. is the dynamic uniaxial compressive strength, 2-2) Determine the equivalent rock mass dynamic cohesion c and equivalent rock mass dynamic internal friction angle based on the in-situ rock mass dynamic damage and strength parameters In the formula, σ 3max is the maximum confining pressure; 3max and rock mass strength σ cm The calculation method is: In the formula, γ is the gravity, H is the burial depth, γ i and h i are the overlying rock mass and rock thickness, respectively; 2-3) The model boundary is set according to the size of the formation stress, and the maximum and minimum principal stress lateral pressure coefficients are set to λ Hv and λ hv ,Right now: In the formula, σ v is the vertical stress, σ H is the maximum horizontal stress, σ h is the minimum horizontal stress, θ Hy is the angle between the longitudinal axis of the tunnel and the direction of maximum principal stress; 2-4) Carry out numerical simulation excavation according to the full-section or partial excavation method of on-site blasting or mechanical excavation to extract the deformation and stress data and material damage status of key surrounding rock sections and support structures.

7. A deep tunnel support design method considering rock mass dynamic damage according to claim 1, characterized in that: The step 3) comprises: 3-1) The dynamic three-dimensional strength criterion of rock mass is used for static calculation of numerical model, and the dynamic geological strength index is used for dynamic and the dynamic disturbance coefficient To calculate the dynamic response characteristics of the rock mass, the strain rate Derived from the vibration waveform curve of on-site dynamic monitoring; 3-2) Extract the rock mass dynamic damage value and the principal stress value of key rock mass units at each excavation step, and evaluate the influence of dynamic damage on rock mass deformation and stress; 3-3) Combined with the three-dimensional spatial effect, calculate the impact of dynamic damage on the principal stress, strength and failure mode of the rock mass, and clarify the influence of dynamic damage on the rotation of the stress principal axis.

8. The deep tunnel support design method considering rock mass dynamic damage according to claim 1 is characterized in that: The step 4) mainly includes: 4-1) Tunnel dynamic disturbance causes different degrees of damage to the rock mass. The principal stress changes of the surrounding rock and the changes of the damaged area caused by the dynamic damage of the rock mass are obtained through the static-dynamic coupling three-dimensional numerical calculation of deep tunnel excavation. 4-2) Compare the calculation results with those of the static excavation numerical model to calculate the scope and degree of influence of dynamic damage on surrounding rock stress and strain; 4-3) Based on the changes in damage stress caused by tunnel dynamic disturbance, as well as the scope and degree of influence of dynamic damage on static stress, construction measures of "reducing dynamic disturbance" are proposed, and support optimization design of "stress transfer and compensation" is adopted to improve the bearing capacity of the rock mass itself, and its effectiveness is verified by substituting it into the numerical model for calculation.

9. A deep tunnel support design method considering rock mass dynamic damage according to claim 1, characterized in that: The step 5) adopts a variety of active control methods to prevent rock mass disasters caused by dynamic disturbances in deep tunnels; The construction measures include one or more of smooth blasting parameter control, over-break and under-break control, multi-step excavation and partial excavation; The support design optimization includes the advance grouting range at the top of the face, the advance core rock reinforcement strength and range, the type and depth of the targeted anchor bolts, and the use of either radial or annular yielding support.

10. The deep tunnel support design method considering rock mass dynamic damage according to claim 1, characterized in that: The core of active control of surrounding rock is to transform the rock mass from an unstable state to a stable state, especially to make the rock mass within the failure surface of the three-dimensional dynamic strength under dynamic disturbance, so that the rock mass does not suffer sudden dynamic damage.

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