Tunnel surrounding rock section monitoring point determination method, system and equipment and storage medium

Abstract

The invention provides a tunnel surrounding rock section monitoring point determination method, system and device and a storage medium, and the method comprises the steps: obtaining tunnel design parameters, and constructing a tunnel surrounding rock structure model according to the design parameters; combining a plurality of excavation methods into a plurality of excavation schemes, and performing simulated excavation on the tunnel surrounding rock structure model by using each excavation scheme to obtain corresponding deformation of surrounding rock sections around the tunnel; according to the deformation amount of the surrounding rock section, deformation and failure characteristics of rock mass around the tunnel are estimated, and a monitoring point is determined; in the actual excavation process, a monitoring device is arranged at a monitoring point, and the surrounding rock section around the tunnel is monitored. According to the invention, the problems that the measurement error is high and the stability control and the monitoring early warning of the small-clear-distance overlapping tunnel are insufficient due to the fact that the arrangement position of the monitoring device can only be set according to the experience of a worker in the construction of the extremely-small-clear-distance overlapping tunnel in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel stability monitoring, and particularly to a method, a system, a device and a storage medium for determining monitoring points in a tunnel surrounding rock section. Background Art

[0002] With the acceleration of the global urbanization process, urban rail transit, as an important means to relieve urban traffic congestion and improve travel efficiency, has developed rapidly worldwide in recent decades. The construction of rail transit systems, especially subway tunnel projects, has become a landmark project in modern urban infrastructure construction. Against the background of increasingly tight urban land resources, the construction of subway tunnels is gradually developing from single tunnels to complex structures, small clear distance overlapping tunnels, etc. The construction of small clear distance overlapping tunnels makes the cross-disturbance situation in specific areas more frequent, seriously affecting the safety and stability during tunnel construction, and at the same time putting forward higher requirements for construction methods, surrounding rock stability control and monitoring and early warning technologies during tunnel construction.

[0003] At present, for the tunnel stability problem during the construction of small clear distance overlapping tunnels, on the one hand, it is roughly evaluated through a preliminary investigation of the surrounding rock geological conditions, but this has great subjectivity and uncertainty and cannot objectively reflect the tunnel stability. On the other hand, it is to measure the displacement of the tunnel wall during the tunnel construction process, and through scientific calculation means, the stability of the surrounding rock is analyzed to correctly evaluate the tunnel stability situation. However, affected by the surrounding rock geology, the positions of the monitoring devices can only be set according to the experience of workers, resulting in a relatively high measurement error, so that the stability control and detection and early warning of small clear distance overlapping tunnels are insufficient. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the present invention provides a method, a system, a device and a storage medium for determining monitoring points in a tunnel surrounding rock section, which solves the problems in the prior art that during the construction of extremely small clear distance overlapping tunnels, the positions of the monitoring devices can only be set according to the experience of workers, resulting in a relatively high measurement error, so that the stability control and monitoring and early warning of small clear distance overlapping tunnels are insufficient.

[0005] According to an embodiment of the present invention, a method for determining monitoring points in a tunnel surrounding rock section includes:

[0006] Obtain tunnel design parameters and construct a tunnel surrounding rock structure model according to the design parameters;

[0007] Combine multiple excavation methods into multiple excavation schemes, and use each excavation scheme to respectively simulate the excavation of the tunnel surrounding rock structure model to obtain the corresponding deformation amount of the surrounding rock section around the tunnel;

[0008] Estimate the deformation and failure characteristics of the rock mass around the tunnel based on the deformation amount of the surrounding rock section, and determine the monitoring points;

[0009] During the actual excavation process, set up monitoring devices at the monitoring points to monitor the surrounding rock section of the tunnel.

[0010] Preferably, the tunnel surrounding rock structure model includes a tunnel structure model and a rock and soil body structure model;

[0011] The excavation method includes numerical simulation of tunnel excavation and numerical simulation of shield tunneling excavation.

[0012] Preferably, the method for numerical simulation of CD method tunnel excavation includes:

[0013] A1: Assign attributes to the rock and soil body structure model, and divide the tunnel excavation process into multiple cyclic excavation segments;

[0014] A2: Separate the excavated rock mass from the rock and soil body structure model, separate the primary support and the secondary lining from the tunnel structure model, then cut the excavated rock mass into multiple rock mass small blocks, cut the primary support into multiple support blocks with the same number as the rock mass small blocks, and keep the secondary lining as a whole without division;

[0015] A3: Use geotechnical numerical simulation software to make the primary support and the secondary lining ineffective, and then according to the excavation path, make the rock mass small blocks in the same cross-section ineffective in sequence, and activate the support blocks located in the same cross-section at the same time;

[0016] A4: After completing one cyclic excavation segment, activate the secondary lining of the corresponding length;

[0017] A5: Repeat steps A3 - A4 until the excavation of the entire tunnel is completed, record the deformation amount of the rock and soil body structure model during the entire excavation process, and use it as the deformation amount of the surrounding rock section.

[0018] Preferably, the method for numerical simulation of shield tunneling excavation includes:

[0019] B1: Assign attributes to the rock and soil body structure model, and divide the tunnel excavation process into multiple cyclic excavation segments;

[0020] B2: Separate the excavated rock mass from the rock and soil body structure model, separate the shield shell and the segment from the tunnel structure model, then divide the excavated rock mass into multiple ring rock masses, divide the shield shell into multiple ring shells, and divide the segment into multiple ring segments;

[0021] B3: Use geotechnical numerical simulation software, according to the excavation path, make the first ring rock mass ineffective, activate the ring shell in the same cross-section, and assign pressure data of the ring rock mass to the ring shell;

[0022] B4: Invalidate the next ring rock mass and the pressure data of the first ring shell, activate the next ring shell in sequence, and assign pressure data to the next ring shell;

[0023] B5: After completing the excavation of multiple cyclic excavation segments as required, starting from the first shield shell, after each cyclic excavation segment is completed, invalidate the currently activated ring shells in sequence, and activate the segments and the next shield shell on the same cross-section;

[0024] B6: Repeat steps B4 - B5 until the entire tunnel excavation is completed, record the deformation of the rock and soil mass structure model during the entire excavation process, and use it as the deformation of the surrounding rock segment.

[0025] Preferably, the excavation plan includes the CD tunnel first and the shield tunnel second plan, the two tunnel excavation methods carried out simultaneously plan, the synchronous pitch shield tunnel first and the CD tunnel second plan, and the asynchronous pitch shield tunnel first and the CD tunnel second plan;

[0026] Among them, the asynchronous pitch shield tunnel first and the CD tunnel second plan includes multiple working conditions, and the pitch between the two excavation methods in each working condition shows an arithmetic progression relationship.

[0027] Preferably, in the numerical simulation of CD method tunnel excavation and shield method tunnel excavation, after assigning attributes to the rock and soil mass structure model, boundary conditions and gravity loads need to be added to the rock and soil mass structure model, and the initial displacement field of the rock and soil mass structure model is cleared.

[0028] Preferably, the thickness of the small rock mass and the support block is the same, and the thickness of the ring rock mass, the ring shell and the segment is the same.

[0029] On the other hand, according to the embodiments of the present invention, a system for determining monitoring points of a tunnel surrounding rock segment is further provided. The system uses the above-mentioned system for determining monitoring points of a tunnel surrounding rock segment, including:

[0030] A modeling system for constructing a tunnel surrounding rock structure model according to tunnel design parameters;

[0031] A simulation system for numerically simulating tunnel excavation of the tunnel surrounding rock structure model to obtain the deformation of the surrounding rock segment;

[0032] An analysis module for determining the deformation and failure characteristics of the predicted rock mass around the tunnel according to the deformation of the surrounding rock segment obtained from the numerical simulation, and determining the monitoring points.

[0033] On the other hand, according to an embodiment of the present invention, there is also provided a computer device, including a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor is caused to execute the above-mentioned method for determining monitoring points of a tunnel surrounding rock section.

[0034] On the other hand, according to an embodiment of the present invention, there is also provided a computer storage medium storing a computer program. When the computer program is executed by a processor, the processor is caused to execute the above-mentioned method for determining monitoring points of a tunnel surrounding rock section.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] Construct the design parameters of the tunnel to be excavated into a tunnel surrounding rock structure model, and simulate the excavation of the model according to the used tunnel excavation method. Record the deformation amount of the tunnel surrounding rock structure during the simulated excavation, and accurately determine the positions where the monitoring devices need to be arranged during the actual excavation according to the deformation amount, so as to more accurately record various parameters during the excavation process and ensure the stability of the tunnel during the subsequent tunnel excavation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flowchart for determining monitoring points in an embodiment of the present invention.

[0038] Figure 2 It is a schematic diagram of the whole excavated rock mass in an embodiment of the present invention.

[0039] Figure 3 It is a schematic diagram of primary support treatment in an embodiment of the present invention.

[0040] Figure 4 It is a schematic diagram of secondary lining treatment in an embodiment of the present invention.

[0041] Figure 5 It is a distribution diagram of surface settlement monitoring points in an embodiment of the present invention.

[0042] Figure 6 It is a comparison diagram of surface settlement under different excavation sequences in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The technical solutions in the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] As Figure 1 shown, an embodiment of the present invention proposes a method for determining monitoring points of a tunnel surrounding rock section, including:

[0045] Obtain tunnel design parameters and construct a tunnel surrounding rock structure model according to the design parameters;

[0046] In the implementation of tunnel engineering, the construction procedures for a single tunnel include excavation, initial support, and subsequent secondary lining. However, when two adjacent tunnels are excavated in parallel, this process becomes more complex. The construction of the leading tunnel is not only accompanied by secondary and tertiary stress redistributions caused by its own excavation and support processes but also inevitably affected by the fourth and fifth stress redistributions generated during the excavation and support of the subsequent tunnel. The interweaving of this multiple stress state makes the stress environment of the leading tunnel far more complex and variable than that during the excavation of a single tunnel.

[0047] Therefore, when modeling, it is necessary to model both tunnels simultaneously, collect the design parameters of the leading tunnel and the trailing tunnel, and import the design parameters into geotechnical engineering numerical simulation software to construct a geotechnical structure model and a tunnel structure model. The design parameters include the cross-sectional dimensions of the leading tunnel and the trailing tunnel, the net distance between the tunnels, the angular spatial position relationship, and the geological conditions.

[0048] When establishing the model, it is necessary to clarify the analysis purpose and pay attention to the important factors affecting the results while simplifying the model. By reasonably simplifying the model, the main factors of the research object can be better highlighted, thus assisting in decision-making in engineering design and practice. This embodiment simplifies the establishment of the geotechnical structure model and the tunnel structure model and proposes the following basic assumptions: The geotechnical body is regarded as an isotropic ideal elastoplastic material, cracks are not considered, and no relative sliding occurs between parts; The elastoplastic constitutive model of the geotechnical body adopts the Mohr-Coulomb model criterion, and other tunnel structures are regarded as elastic materials; The ground surface is horizontal and there are no other buildings within the simulation range; The initial stress field of the geotechnical body only considers the self-weight stress field, and the tectonic stress field and secondary stress field of the geotechnical body are ignored; When conducting the simulation, the influence of the groundwater level and seepage within the model range is not considered; To simplify the grouting reinforcement effect of the advanced small pipes, the simulation process will be achieved by changing the material properties of the reinforcement area; Using the limit idea, the excavation of the extremely small clear distance tunnel is simulated in the most unfavorable state.

[0049] Combine multiple excavation methods into multiple excavation schemes, and use each excavation scheme to separately simulate the excavation of the tunnel surrounding rock structure model to obtain the corresponding deformation amount of the surrounding rock section around the tunnel.

[0050] There are two common tunnel excavation methods, namely CD method tunnel excavation and shield method tunnel excavation. Different excavation methods and different excavation step distances for the leading tunnel and the trailing tunnel will have different effects on the stress of the surrounding rock and soil mass of the tunnel. Therefore, in order to comprehensively monitor the entire tunnel excavation process, 4 excavation methods are designed: the CD tunnel leading and the shield tunnel trailing method, the two tunnels excavated simultaneously method, the shield tunnel leading with the same step distance and the CD tunnel trailing method, and the shield tunnel leading with different step distances and the CD tunnel trailing method. Among them, the shield tunnel leading with different step distances and the CD tunnel trailing method includes multiple working conditions, and the step distance between the two excavation methods in each working condition shows an arithmetic progression relationship.

[0051] The numerical simulation method for CD method tunnel excavation includes:

[0052] A1: Assign attributes to the rock and soil mass structure, add boundary conditions and gravity loads to the rock and soil mass structure, clear the initial displacement field of the rock and soil mass structure, and divide the tunnel excavation process into multiple cyclic excavation segments;

[0053] A2: As Figure 2 - Figure 4 shown, separate the excavated rock mass from the rock and soil mass structure, separate the primary support and the secondary lining from the tunnel structure, then cut the excavated rock mass into multiple rock mass small pieces, cut the primary support into multiple support pieces with the same number as the rock mass small pieces, and keep the secondary lining as a whole without segmentation;

[0054] A3: Use geotechnical numerical simulation software to make the primary support and the secondary lining ineffective, and then according to the excavation path, make the rock mass small pieces in the same cross-section ineffective in sequence, and activate the support pieces located in the same cross-section at the same time;

[0055] A4: After completing a cyclic excavation segment, activate the secondary lining of the corresponding length;

[0056] A5: Repeat steps A3 - A4 until the entire tunnel excavation is completed, record the deformation of the rock and soil mass structure during the entire excavation process, and take it as the deformation of the surrounding rock segment.

[0057] Operations such as property assignment, boundary condition restriction, gravity load addition, and in-situ stress balance to the geotechnical structure model ensure the authenticity and reliability of the model, can fully consider the physical and mechanical properties of the geotechnical body, and provide accurate initial conditions for subsequent excavation simulation. The rock mass to be excavated is divided into at least two ring rock masses according to the cyclic step distance and further subdivided into four rock mass small blocks, which can more realistically simulate the rock mass fragmentation during the actual excavation process. At the same time, the same treatment method as the excavated rock mass is adopted for the primary support, and the thickness of the rock mass small block and the support block is the same, which can ensure the close fit between the support structure and the rock mass and improve the support effect. The secondary lining remains integral without division, which helps to enhance the overall stability and safety of the tunnel. By sequentially making the four rock mass small blocks in each ring rock mass ineffective to simulate the excavation process and simultaneously activating the corresponding primary support part, the excavation sequence and support timing in actual construction can be more accurately simulated, thus more realistically reflecting the stress change and deformation of the surrounding rock. This helps to timely discover potential safety hazards and provides strong support for risk prevention and control during the construction process. After completing one cycle of excavation, the corresponding length of the secondary lining is activated. This treatment method can ensure that the secondary lining plays a role in time and jointly bears the pressure of the surrounding rock with the primary support. This can not only enhance the bearing capacity of the tunnel but also help to reduce the risk of deformation and failure of the surrounding rock. By repeating steps A3 - A4 until the tunnel excavation is completed, a comprehensive simulation of the continuous tunnel excavation process is achieved. This continuous simulation method can fully consider the influence of various factors during the construction process, including excavation sequence, support timing, rock mass fragmentation, etc., and provides a reliable basis for subsequent setting of monitoring points.

[0058] The numerical simulation method for shield tunneling includes:

[0059] B1: Assign properties to the geotechnical structure and divide the tunnel excavation process into multiple cyclic excavation segments;

[0060] B2: Separate the excavated rock mass from the geotechnical structure, separate the shield and segments from the tunnel structure, then divide the excavated rock mass into multiple ring rock masses, divide the shield into multiple ring shells, and divide the segments into multiple ring segments;

[0061] B3: Use geotechnical numerical simulation software, according to the excavation path, make the first ring rock mass ineffective, activate the ring shell on the same section, and assign pressure data of the ring rock mass to the ring shell;

[0062] B4: Make the next ring rock mass ineffective and the pressure data of the first ring shell ineffective, activate the next ring shell in sequence and assign pressure data to the next ring shell;

[0063] B5: After the excavation of multiple circular excavation sections is completed according to the requirements, starting from the first shield shell, after each circular excavation section is completed, the currently activated ring shell is deactivated in sequence, and the segment in the same cross-section and the next shield shell are activated.

[0064] B6: Repeat steps B4 - B5 until the entire tunnel excavation is completed, record the deformation of the rock and soil structure during the entire excavation process, and use it as the deformation of the surrounding rock section.

[0065] Step B1 ensures that the initial conditions of the numerical simulation are highly consistent with the actual situation, laying a solid foundation for the accuracy of subsequent excavation simulations. By clearing the initial displacement field of the model, the influence of the initial state on the simulation results is eliminated. Dividing the rock mass to be excavated into multiple circular rock masses can more accurately simulate the actual working conditions of the shield machine during the excavation process. At the same time, the shield shell and segments are treated in the same way as the rock mass to be excavated, forming ring shells and segments of the same thickness respectively, ensuring the synergistic effect between components during the simulation process and making the simulation results closer to the actual construction situation. By deactivating the rock mass where the first ring of the tunnel is located and activating the shield shell and assigning pressure data to the ring shell for the surrounding rock mass (equivalent to the pressure of the shield machine on the first face), the instantaneous state when the shield machine starts working is truly restored. Accurate simulation helps to analyze the stress changes and deformation conditions at the initial stage of tunnel excavation. By simulating the propulsion process of the shield machine by deactivating and activating the pressures of different faces, the dynamic behavior of the shield machine during actual construction can be accurately reflected, including key parameters such as propulsion speed and thrust magnitude. This helps to timely detect possible problems during the propulsion process of the shield machine. By deactivating the first shield shell and activating the first segment, the actual construction situation of the tunnel support structure is truly simulated, which helps to analyze the influence of the support structure on the tunnel stability and the interaction mechanism between the support structure and the surrounding rock. By repeating steps B4 - B5 until the tunnel excavation is completed, a comprehensive simulation of the continuous tunnel excavation process is achieved, which can fully consider the forces and deformations caused by the dynamic changes of various factors during the construction process, including geological conditions, shield machine performance, support structure status, etc., providing a reliable basis for subsequent setting of monitoring points.

[0066] Estimate the deformation and failure characteristics of the rock mass around the tunnel based on the deformation of the surrounding rock section, and determine the monitoring points.

[0067] The deformation of the surrounding rock section includes ground settlement, stress field, displacement field, and plastic zone.

[0068] There are four types of the above excavation schemes: the CD tunnel first and the shield tunnel second scheme (working condition one), the two tunnel excavation methods carried out simultaneously scheme (working condition two), the synchronous pitch shield tunnel first and the CD tunnel second scheme (working condition three), and the asynchronous pitch shield tunnel first and the CD tunnel second scheme (working condition four).

[0069] The ground settlement characteristics and characteristic values of the first three excavation schemes are compared and analyzed to obtain the data in Table 1.

[0070] Table 1:

[0071]

[0072] As can be seen from Table 1, the ground settlement value is the smallest and the settlement range width is the smallest when the shield tunnel is excavated first and the CD tunnel is excavated later. Therefore, the excavation sequence of the shield tunnel first and the CD tunnel later is a reasonable choice to ensure the stability of the surrounding rock.

[0073] As Figure 6 shown, the settlement amounts of the ground settlement monitoring points under the three working conditions are extracted for analysis and comparison. It can be seen that the distribution laws of the ground settlement obtained by excavating the tunnel in the three construction sequences are roughly the same, all showing a single-peak asymmetric distribution. When the two tunnels are excavated successively, the maximum settlement amount is located at the ground surface on the axis of the first tunnel, indicating that the first tunnel has a major influence on the ground settlement; the settlement amount on one side of the second tunnel relative to the first tunnel is larger than that on the other side after the second tunnel is excavated, indicating that the excavation of the second tunnel will cause secondary settlement of the ground above it.

[0074] The characteristics of the maximum principal stress and the minimum principal stress of the three excavation sequences are compared to obtain the data in Table 2.

[0075] Table 2:

[0076]

[0077] During the tunnel excavation process, the larger the tensile stress and compressive stress of the maximum principal stress of the surrounding rock, the more easily the surrounding rock is damaged by tension and compression. From the data in the table, considering the stress field of the surrounding rock, the tensile stress of the maximum principal stress in the excavation sequence of the shield tunnel first and the CD tunnel later is the smallest among the three excavation sequences, and the compressive stress of the maximum principal stress and the compressive stress of the minimum principal stress are not much different from those of the other two excavation sequences.

[0078] The maximum principal stress and the minimum principal stress of the support structure under the three working conditions are compared to obtain the data in Table 3.

[0079] Table 3:

[0080]

[0081] As can be seen from the table: the stresses on the support structure of the first tunnel are all very small, and the stresses on the support structure of the second tunnel are all very large.

[0082] This characteristic indicates that after the excavation of the leading tunnel, the initial stress balance state of the surrounding rock is broken, the stress state changes, and a stress increase zone is formed around the tunnel contour surface, that is, the self-bearing capacity of the surrounding rock. After most of the stress is borne by the surrounding rock itself, the support structure of the leading tunnel only bears a very small part of the stress; when the trailing tunnel is excavated, the stress state of the surrounding rock is redistributed. At this time, due to the excavation of the leading tunnel, the stress state of the surrounding rock undergoes significant redistribution, resulting in an increase in the deformation of the surrounding rock and the inability to effectively form an arch. This kind of redistribution often causes the stress of the surrounding rock to transfer to the support structure, and the support structure bears most of the stress of the surrounding rock, especially the support structure on the side close to the leading tunnel, where larger principal stresses appear.

[0083] When the tunnels are excavated simultaneously, the interval of disturbance to the surrounding rock is short and can be regarded as a one-time disturbance. The surrounding rocks of both tunnels effectively form arches and bear most of the stress. Therefore, the stresses of the support structures of the two tunnels are very small when the CD tunnel and the shield tunnel are excavated simultaneously.

[0084] Under the three excavation sequences, the distribution laws of the vertical displacement and horizontal displacement of the surrounding rock are compared and analyzed, and the data in Table 4 are obtained:

[0085] Table 4:

[0086]

[0087] It can be seen from the table that the vertical positive displacement is distributed in the lower half area of the leading tunnel, and the vertical negative displacement is distributed in the upper half area of the leading tunnel; the horizontal positive displacement of the surrounding rock is distributed in the left part area of the leading tunnel, and the negative displacement is distributed in the right part area of the leading tunnel. After the excavation of the trailing tunnel, its vertical displacement and horizontal displacement are concentrated in the area close to the leading tunnel. During the construction of the extremely small clear distance tunnel, the displacement of the surrounding rock mainly occurs in the surrounding rock around the leading tunnel, and the displacement of the surrounding rock of the trailing tunnel is concentrated on the side closer to the leading tunnel.

[0088] For working condition 4, the shield tunnel is set as the leading tunnel and the CD method tunnel is set as the trailing tunnel. By setting 4 different working conditions with excavation steps of 2m, 3m, 4m, and 5m, the surface settlement, stress field, displacement field, and plastic zone distribution are compared and analyzed to explore the influence of different CD method excavation steps on the stability of the surrounding rock under the extremely small clear distance tunnel.

[0089] The surface settlement characteristics and characteristic values of the four excavation steps are compared and analyzed, and the data in Table 5 are obtained:

[0090] Table 5:

[0091] Excavation step distance Maximum settlement Location of maximum settlement Width of settlement range 2m 1.57 mm At the ground surface on the CD tunnel axis 42m 3m 1.77 mm At the ground surface on the CD tunnel axis 48m 4m 1.86 mm At the ground surface on the CD tunnel axis 50m 5m 2.02 mm At the ground surface on the CD tunnel axis 52m

[0092] As can be seen from the table, as the excavation step distance increases, the maximum surface settlement value and the width of the settlement range also increase; the position of the maximum settlement is near the surface above the CD tunnel axis and does not change with the excavation step distance.

[0093] Comparative analysis was carried out on the characteristics of the maximum principal stress of the surrounding rock under four excavation step distances, and the data in Table 6 were obtained.

[0094] Table 6:

[0095]

[0096] It can be seen from the comparative analysis of the above table that as the excavation step distance increases, the maximum value of the tensile stress of the maximum principal stress of the surrounding rock increases, and the position is at the surrounding rock at the bottom of the CD tunnel structure; the maximum values of the compressive stress of the maximum principal stress of the surrounding rock under the four excavation step distances are not much different and the positions are the same, indicating that the excavation step distance has a weak influence on the compressive stress of the maximum principal stress. Under the four excavation step distances, the maximum principal stress at the arch bottom in the support structure is larger than that in other parts. The overall maximum principal stress of the support structure for the excavation step distances of 3m and 4m is smaller than that for 2m and 5m.

[0097] Comparative analysis was carried out on the characteristics of the minimum principal stress of the surrounding rock under four excavation step distances, and the data in Table 7 were obtained:

[0098] Table 7:

[0099]

[0100]

[0101] It can be seen from the comparative analysis of the above table that as the excavation step distance increases, the compressive stress of the minimum principal stress of the surrounding rock at the right arch waist of the shield tunnel increases. It shows that the smaller the excavation step distance, the better the stability of the surrounding rock at the right arch waist of the shield tunnel.

[0102] The characteristics of the horizontal displacement of the surrounding rock under four excavation step distances were compared and analyzed, and the data in Table 8 were obtained.

[0103] Table 8:

[0104]

[0105] It can be seen from the comparative analysis of the above table that different excavation step distances have different influences on the vertical displacement of the surrounding rock. When constructing with an excavation step distance of 2m, the horizontal displacement of the surrounding rock in the negative direction of the Y-axis is smaller than that of the other three excavation step distances; when constructing with an excavation step distance of 5m, the horizontal displacement of the surrounding rock in the positive direction of the Y-axis is smaller than that of the other three excavation step distances.

[0106] According to the above analysis, monitoring points are set up. The monitoring points include surface settlement monitoring points and tunnel support structure monitoring points. Specifically, for the surface settlement monitoring points: taking the initial excavation section of the geotechnical structure model as the first monitoring surface, monitoring points are set at intervals of 4 m on the detection surface, and a total of 25 monitoring points are set; as Figure 5 shown, taking the surface at the axis of the excavated tunnel as point A0, there are 12 points in each of the left and right B and C series of points, and point C2 is located on the axis of the shield tunnel.

[0107] Specifically, for the tunnel support structure monitoring points: taking the cross-section of the tunnel structure model as the second monitoring surface, monitoring points are set at the crown, invert, shoulders, waists and feet of the second monitoring surface.

[0108] After that, during the actual excavation process, monitoring devices are set at the monitoring points to monitor the surrounding rock sections of the tunnel.

[0109] The monitoring scope of the present invention is extensive, including whether the support structure of the project itself meets the specifications and design requirements, the safety of important appendages around the support structure, the potential impact of tunnel construction on the surrounding environment, and the structural safety when the tunnel passes through a bridge.

[0110] The monitoring items and objects are detailed and comprehensive, covering the direct observation of geological and support conditions, the settlement of roads and the surface, crown settlement and clearance convergence, the settlement and inclination of bridges and retaining walls, and the settlement and horizontal displacement of side piles and steel pipe columns. In terms of monitoring accuracy, the measurement of groundwater level and clearance convergence is particularly refined, and there are also strict accuracy requirements for the monitoring of surface settlement, underground pipelines, initial lining crown settlement, and adjacent buildings, bridges and retaining walls to ensure the accuracy and reliability of the data.

[0111] In order to achieve effective monitoring, a variety of methods are used to collect key data such as the settlement of the road and the surface above the tunnel, crown subsidence, clearance convergence and base heave. At the same time, through data transmission, the acquisition system composed of multiple sensors can upload data in real time, providing a solid foundation for subsequent tunnel deformation analysis.

[0112] Tunnel deformation analysis is the core part of the monitoring work. By analyzing data such as the settlement of the road and the surface above the tunnel, crown subsidence, clearance convergence and base heave, the lateral and longitudinal deformations of the tunnel body can be determined, and then the change of the tunnel clearance displacement can be understood.

[0113] On the other hand, the embodiment of the present invention also provides a system for determining monitoring points of a tunnel surrounding rock section. The system uses the above-mentioned system for determining monitoring points of a tunnel surrounding rock section, including:

[0114] A modeling system, which is used to construct a tunnel surrounding rock structure model according to tunnel design parameters;

[0115] A simulation system for numerically simulating tunnel excavation on a tunnel surrounding rock structure model to obtain the deformation amount of the surrounding rock section.

[0116] An analysis module for determining the deformation and failure characteristics of the predicted rock mass around the tunnel based on the deformation amount of the surrounding rock section obtained from the numerical simulation and determining the monitoring points.

[0117] On the other hand, an embodiment of the present invention further provides a computer device, including a memory and a processor. When the computer program stored in the memory is executed by the processor, the processor is caused to execute the above-mentioned method for determining the monitoring points of a tunnel surrounding rock section.

[0118] On the other hand, an embodiment of the present invention further provides a computer storage medium storing a computer program. When the computer program is executed by a processor, the processor is caused to execute the above-mentioned method for determining the monitoring points of a tunnel surrounding rock section.

[0119] 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 the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for determining monitoring points in a tunnel surrounding rock section, characterized in that: include: Obtain tunnel design parameters and construct a tunnel surrounding rock structure model based on the design parameters; Combining multiple excavation methods into multiple excavation schemes, and using each excavation scheme to simulate the excavation of the tunnel surrounding rock structure model, to obtain the corresponding deformation of the surrounding rock section around the tunnel; Estimate the deformation and failure characteristics of the rock mass around the tunnel based on the deformation of the surrounding rock section and determine the monitoring points; During the actual excavation process, monitoring devices are set up at monitoring points to monitor the surrounding rock sections around the tunnel.

2. A method for determining monitoring points in a tunnel surrounding rock section according to claim 1, characterized in that: The tunnel surrounding rock structure model includes a tunnel structure model and a rock and soil structure model; The excavation method includes tunnel excavation numerical simulation and shield tunnel excavation numerical simulation.

3. A method for determining monitoring points in a tunnel surrounding rock section according to claim 2, characterized in that: The CD tunnel excavation numerical simulation method comprises: A1: Assign attributes to the rock and soil structure model and divide the tunnel excavation process into multiple cyclic excavation segments; A2: Separate the excavated rock mass from the rock and soil structure model, separate the primary support and secondary lining from the tunnel structure model, and then cut the excavated rock mass into multiple small rock blocks, cut the primary support into multiple support blocks with the same number of rock blocks, and keep the secondary lining as a whole; A3: Use geotechnical numerical simulation software to make the primary support and secondary lining fail, then sequentially fail the rock blocks in the same section according to the excavation path, and activate the support blocks in the same section at the same time; A4: After completing a cycle excavation section, activate the secondary lining of the corresponding length; A5: Repeat steps A3-A4 until the excavation of the entire tunnel is completed, and record the deformation of the rock and soil structure model during the entire excavation process, and use it as the deformation of the surrounding rock section.

4. A method for determining monitoring points in a tunnel surrounding rock section according to claim 3, characterized in that: The methods for numerical simulation of shield tunnel excavation include: B1: Assign attributes to the rock and soil structure model and divide the tunnel excavation process into multiple cyclic excavation segments; B2: Separate the excavated rock mass from the rock and soil structure model, separate the shield shell and the segment from the tunnel structure model, and then divide the excavated rock mass into multiple ring rock masses, divide the shield shell into multiple ring shells, and divide the segment into multiple ring segments; B3: Using geotechnical numerical simulation software, according to the excavation path, the first ring rock mass is invalidated, and the ring shell on the same section is activated, and the pressure data on the ring rock mass is assigned to the ring shell; B4: invalidate the next annular rock mass and the pressure data of the first annular shell, activate the next annular shell in sequence and assign pressure data to the next annular shell; B5: After completing the excavation of multiple cyclic excavation sections according to the needs, starting from the first shield shell, after completing each cyclic excavation section, the currently activated ring shell is deactivated in sequence, and the ring piece and the next shield shell on the same section are activated; B6: Repeat steps B4-B5 until the entire tunnel excavation is completed, and record the deformation of the rock and soil structure model during the entire excavation process and use it as the deformation of the surrounding rock section.

5. A method for determining monitoring points in a tunnel surrounding rock section according to claim 2, characterized in that: The excavation schemes include a CD tunnel first and a shield tunnel second scheme, a two-tunnel excavation method scheme, a synchronous shield tunnel first and a CD tunnel second scheme, and an asynchronous shield tunnel first and a CD tunnel second scheme; The asynchronous shield tunnel-first CD tunnel-later scheme includes multiple working conditions, and the step distances between the two excavation methods in each working condition are in an equidistant relationship.

6. A method for determining monitoring points in a tunnel surrounding rock section according to claim 4, characterized in that: In the CD method tunnel excavation numerical simulation and the shield method tunnel excavation numerical simulation, after the attribute assignment is performed on the rock and soil structure model, it is also necessary to add boundary conditions and gravity loads to the rock and soil structure model, and clear the initial displacement field of the rock and soil structure model.

7. A method for determining monitoring points in a tunnel surrounding rock section according to claim 4, characterized in that: The thickness of the rock mass blocks and the supporting blocks are the same, and the thickness of the ring rock mass, the ring shell and the ring sheet are the same.

8. A system for determining monitoring points in a tunnel surrounding rock section, characterized in that: The system uses a tunnel surrounding rock section monitoring point determination system as described in any one of claims 1 to 7, comprising: A modeling system, wherein the modeling system is used to construct a tunnel surrounding rock structure model according to tunnel design parameters; A simulation system, wherein the simulation system is used to perform numerical simulation of tunnel excavation on a tunnel surrounding rock structure model to obtain deformation of the surrounding rock section; The analysis module is used to determine and estimate the deformation and failure characteristics of the rock mass around the tunnel according to the deformation of the surrounding rock section obtained by numerical simulation, and to determine the monitoring points.

9. A computer device, characterized in that: It comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes a method for determining monitoring points of a surrounding rock section of a tunnel as described in any one of claims 1 to 7.

10. A computer storage medium, characterized in that: A computer program is stored, and when the computer program is executed by a processor, the processor executes a method for determining monitoring points in a tunnel surrounding rock section as described in any one of claims 1 to 7.

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