A method for classifying engineering activities in subway tunnel protection zones

Abstract

This invention relates to a method for classifying engineering activities within a subway tunnel protection zone, primarily addressing the technical problems of existing classification methods that lack comprehensive coverage of classification factors and overly general classification standards. Specifically, it involves: establishing a standard for delineating subway tunnel safety protection zones based on the impact of each type of engineering activity on adjacent subway tunnels; obtaining relevant structural parameters of existing subway tunnels and external construction projects, as well as geological parameters of the construction area; substituting these parameters into the calculation formula for the protection zone boundary of that engineering activity type; and analyzing the relationship between the tunnel location and each level of protection zone to determine the engineering safety management level. This method rationally delineates subway tunnel safety protection zones for different types of engineering activities, accurately controlling engineering risks associated with adjacent subway tunnels and providing a reasonable basis for engineering design and the implementation of safety protection measures within subway tunnel protection zones.

Description

Technical Field

[0001] This invention belongs to the field of tunnel engineering safety technology, and in particular relates to a method for classifying engineering activities in a subway tunnel protection zone. Background Technology

[0002] In recent years, with the continuous improvement of underground engineering technology, construction projects within tunnel protection zones have become increasingly common. The mutual impact between new projects and existing tunnels has become a major issue in the construction process. Due to the complex and varied influencing factors of different types of construction projects on existing tunnels, achieving a graded assessment and precise protection of existing tunnel conditions remains challenging. Therefore, in order to systematically and efficiently evaluate the safety impact of construction projects within subway tunnel protection zones, it is necessary to propose a quantitative classification method for the safety levels of projects within these zones. This method would provide a reasonable basis for engineering design and the implementation of safety protection measures within subway tunnel protection zones, enabling staff to easily and conveniently determine the safety level based on the engineering design.

[0003] CN106910002A, "Method for Safety Assessment of Metro Tunnel Structures," is based on the stress and deformation characteristics of tunnel structures. It selects various tunnel defects as evaluation indicators and establishes a tunnel structure safety evaluation index system according to existing safety level classification methods, relevant specifications, and tunnel stress and deformation control standards. However, this method is only applicable to evaluating the structural safety of metro tunnels during their service life and is not suitable for assessing the impact of proposed projects on existing metro tunnels.

[0004] CN104102525B, "A Risk Classification and Control Method for Engineering Projects Crossing Urban Rail Transit," addresses construction projects that intersect or are adjacent to rail transit lines and facilities and affect their safety. It classifies the impact level range based on the specific construction methods and scope of existing rail transit, and establishes risk levels based on relevant design and construction data and factors. However, this method only classifies the impact level based on the construction methods and scope of existing rail transit, without considering other types of engineering activities, and is therefore incomplete.

[0005] CN109063955A, "A Method for Classifying and Handling Operational Impact Levels of Subway Crossing Projects," comprehensively considers the operational impact zone of newly constructed external projects and the impact identification zone of existing subway lines, classifying operational impact levels and formulating corresponding engineering risk handling methods. However, this method only uses single structural dimensions in newly constructed projects, such as tunnel diameter, underground station structural height, and pile foundation diameter, as the classification standard, making the classification standard too general. Summary of the Invention

[0006] The purpose of this invention is to provide a classification method for engineering activities in subway tunnel protection zones, which mainly solves the technical problems of existing classification methods, such as incomplete coverage of classification factors and overly general classification standards.

[0007] The technical solution of this invention is: a method for classifying engineering activities in a subway tunnel protection zone, comprising the following steps:

[0008] S1. Establish a standard for delineating the safety protection zone of subway tunnels based on the degree of safety impact of each type of engineering activity on the adjacent subway tunnels;

[0009] S2. Obtain relevant structural parameters of existing subway tunnels and external construction projects, geological parameters of the construction area, and health status level of existing subway tunnels;

[0010] S3. Substitute the formula for calculating the protected area classification boundary of this type of engineering activity;

[0011] S4. Analyze the relationship between the tunnel location and protection zones of various levels to preliminarily determine the safety management level of the project;

[0012] S5. Based on the existing health status level of the subway tunnel, determine the final project safety management level:

[0013] If the existing subway tunnel has a health status level of 1, the project safety management level remains unchanged;

[0014] If the existing subway tunnel health status level is level 2, the project safety management level will be upgraded from level 3 to level 2, and level 2 will be upgraded to level 1.

[0015] If the existing subway tunnel has a health status level of 3, then the project safety management level will be ultimately determined to be level 1.

[0016] Furthermore, the engineering construction includes single-sided foundation pit engineering, construction of a new parallel underpass tunnel or a new vertical overpass tunnel, and overhead loading or unloading engineering.

[0017] Furthermore, the grading method for the single-sided foundation pit project is as follows:

[0018] when Therefore, the safety management level of this unilateral foundation pit project is Level 1.

[0019] when Therefore, the safety management level of this unilateral foundation pit project is Level 2.

[0020] when Therefore, the safety management level of this unilateral foundation pit project is Level 3.

[0021] In the above formula, B is the distance between the boundary of the adjacent foundation pit and the centerline of the existing subway tunnel, D is the outer diameter of the existing subway tunnel, h is the burial depth of the existing subway tunnel, H1 is the excavation depth of the foundation pit, H2 is the burial depth of the bottom of the diaphragm wall, α1 is the fracture angle of the surrounding rock at the bottom of the foundation pit, and α2 is the fracture angle of the surrounding rock at the bottom of the diaphragm wall. The formula is used to... calculate, It is the internal friction angle of the surrounding rock at the bottom of the foundation pit or the bottom of the underground continuous wall.

[0022] Furthermore, the specific classification method for the newly constructed parallel underpass tunnel project is as follows:

[0023] For the construction condition where a collapsing arch may form above the newly built tunnel, let the crown of the new tunnel arch be the origin, the tunnel cross-section be the xOy plane, the positive y-axis be vertically upward, and the x-axis be horizontally to the right. The center point of the existing subway tunnel cross-section is (x0, y0) and y0 > 0.

[0024] when and The safety management level of the newly constructed parallel underpass tunnel project is Level 1.

[0025] when and or, and The safety management level of the newly constructed parallel underpass tunnel project is Level 2.

[0026] When (x0, y0) is outside the above range, the safety management level of the newly constructed parallel underpass tunnel project is level 3;

[0027] In the above formula, D is the outer diameter of the existing tunnel, B is the half-span of the collapse arch of the new tunnel, h is the height of the collapse arch, b is the half-span of the new tunnel, and H is the height of the new tunnel. It is the internal friction angle of the tunnel surrounding rock.

[0028] Furthermore, when a collapse arch cannot be formed above the newly constructed tunnel, the specific classification method for the newly constructed parallel underpass tunnel project is as follows:

[0029] Let the crown of the new tunnel be the origin, the tunnel cross-section be the xOy plane, the positive y-axis be vertically upward, and the x-axis be horizontally to the right. The center point of the existing subway tunnel cross-section is (x0, y0) and y0 > 0. Then...

[0030] when At that time, the safety management level of the newly constructed parallel underpass tunnel project was Level 1;

[0031] when At that time, the safety management level of the newly constructed parallel underpass tunnel project was Level 2;

[0032] When (x0, y0) is outside the above range, the safety management level of the newly constructed parallel underpass tunnel project is level 3;

[0033] In the above formula, D is the outer diameter of the existing tunnel, b is the half-span of the new tunnel, and H is the height of the new tunnel. The internal friction angle of the surrounding rock at the bottom of the newly constructed tunnel.

[0034] Furthermore, the specific classification method for the newly constructed vertical overpass tunnel project is as follows:

[0035] When s≥20mm, the safety management level of the newly built vertical overpass tunnel project is Level 1;

[0036] When 10mm≤s<20mm, the safety management level of the newly built vertical overpass tunnel project is Level 2;

[0037] When 0 < s < 10 mm, the safety management level of the newly built vertical overpass tunnel project is level 3;

[0038] In the formula, s is the amount of soil deformation above the existing tunnel caused by the construction of the new tunnel;

[0039] Furthermore, s can be estimated according to the following formula:

[0040]

[0041] In the formula, d is the outer diameter of the new tunnel (m), l is the net distance between the new tunnel and the existing tunnel (m), and V l α is the formation loss rate, and α is a constant related to the formation properties, which can be taken as 0.084 for strongly weathered granite formations.

[0042] Furthermore, the grading method for the aforementioned upper surcharge project is as follows:

[0043] when At that time, the safety management level of the overhead loading project was Level 1;

[0044] when At that time, the safety management level of the overhead loading project was Level 2;

[0045] when At that time, the safety management level of the overhead loading project was level 3;

[0046] In the formula, H is the burial depth of the tunnel apex, b is the length of the uniformly distributed load in the plane containing the tunnel cross-section, and p is the magnitude of the uniformly distributed load. This is the pressure diffusion angle of the foundation surrounding rock, which is generally taken as 22°.

[0047] Furthermore, the hierarchical method for the above unloading project is as follows:

[0048] when At that time, the safety management level of the unloading project above was Level 1;

[0049] when At that time, the safety management level of the unloading project above was Level 2;

[0050] when At that time, the safety management level of the unloading project above was level 3;

[0051] In the formula, β is the angle between the tunnel apex and the lines connecting the two ends of the pit, and p is the unloading size in the plane containing the tunnel cross section;

[0052] Furthermore, the geological parameters of the construction area include the thickness of each soil layer, the internal friction angle, and the elastic modulus; the relevant structural parameters include the existing tunnel structure dimensions, the elastic modulus of the segment lining, the structural dimensions of the new project, material parameters, and the control value V for the excavation loss rate of the new tunnel. l .

[0053] The beneficial effects of this invention are as follows: This invention is applicable to the safety level classification of the impact of proposed external engineering activities on existing subway tunnels, including single-sided foundation pit engineering, construction of new parallel underpass or vertical overpass tunnels, and overhead loading or unloading engineering. It fully considers the impact of different structural parameters of the proposed project and its positional relationship with the existing subway tunnel on the deformation or stress of the existing subway tunnel, and classifies various engineering safety management levels, thereby making a more systematic and reasonable judgment on the safety status of engineering construction. The implementation process is simple and the evaluation is more comprehensive. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the classification standards for single-sided foundation pit engineering.

[0055] Figure 2 This is a schematic diagram illustrating the classification standards for parallel underpass tunnel projects.

[0056] Figure 3 A schematic diagram illustrating the classification standards for parallel underpass tunnel projects without collapsed arches.

[0057] Figure 4 This is a schematic diagram illustrating the classification standards for vertical overhead tunnel projects.

[0058] Figure 5 This is a schematic diagram illustrating the hierarchical structure of the loading project above.

[0059] Figure 6 This is a schematic diagram illustrating the hierarchical structure of the unloading process above. Detailed Implementation

[0060] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0061] A method for classifying engineering activities in a subway tunnel protection zone, comprising the following steps:

[0062] 1. Reference Figure 1 A project plans to excavate a foundation pit to a depth of 17 meters, located next to an operating subway tunnel. The tunnel has a diameter of 6.2 meters and a center depth of 12 meters. The foundation pit is 11.5 meters from the center of the track, and the diaphragm wall near the subway tunnel reaches a depth of 33.65 meters. According to the survey data, there are nine engineering geological layers in the foundation pit construction area.

[0063] The specific implementation steps for the quantitative classification of engineering safety are as follows:

[0064] S1. The project is a single-sided foundation pit project within a subway tunnel protection zone. The classification method is as follows:

[0065] when Therefore, the safety management level of this unilateral foundation pit project is Level 1.

[0066] when Therefore, the safety management level of this unilateral foundation pit project is Level 2.

[0067] when Therefore, the safety management level of this single-sided foundation pit project is Level 3. In the above formula, B is the distance between the boundary of the adjacent foundation pit and the centerline of the existing subway tunnel, D is the outer diameter of the existing subway tunnel, h is the burial depth of the existing subway tunnel, H1 is the excavation depth of the foundation pit, H2 is the burial depth of the bottom of the diaphragm wall, α1 is the fracture angle of the surrounding rock at the bottom of the foundation pit, and α2 is the fracture angle of the surrounding rock at the bottom of the diaphragm wall. α1 and α2 can be obtained through formulas. calculate, The internal friction angle of the surrounding rock at the bottom of the foundation pit or the bottom of the underground continuous wall;

[0068] S2. Based on the geological survey report of the foundation pit construction area, obtain the relevant soil layer parameters in the calculation section, as shown in Table 1; the excavation depth of the foundation pit is H1 = 17m, the depth of the underground continuous wall near the tunnel is H2 = 33.65m, and the horizontal distance from the foundation pit to the center of the subway tunnel is B = 11.5m.

[0069] Table 1. Relevant Soil Layer Parameters for Foundation Pit Engineering

[0070]

[0071] Based on the tunnel design data, the relevant structural parameters in the calculation section were obtained: the tunnel diameter is D = 6.2m, the tunnel center burial depth is h = 12m, and based on the periodic inspection data of the operating subway tunnel, the health status level of the subway tunnel was determined to be Level 1.

[0072] S3. Calculate the fracture angle α1 of the surrounding rock at the bottom of the foundation pit and the fracture angle α2 of the surrounding rock at the bottom of the diaphragm wall. The bottom of the foundation pit is located in soil layer ⑤, and the bottom of the diaphragm wall is located in soil layer ⑨. The calculation formulas are as follows:

[0073]

[0074]

[0075] When the excavation pit is located on one side of an existing subway tunnel project, and the distance between the boundary of the adjacent excavation pit and the centerline of the existing subway tunnel is B = 11.5m, calculate the graded boundary values ​​respectively:

[0076]

[0077]

[0078]

[0079] S4. Analysis shows that:

[0080]

[0081] The safety management level of the foundation pit project has been preliminarily determined to be Level 2.

[0082] S5. The existing subway tunnel has a health status level of 1, and the final safety management level of the foundation pit project is determined to be 2.

[0083] 2. Reference Figure 2 , Figure 3 A project plans to construct a new tunnel that runs parallel to and under an existing tunnel. The existing tunnel has a diameter of 6.2m and a center depth of 12m. The relevant geological parameters of the tunnel are shown in Table 2. The new tunnel has an outer diameter of 6.2m, is located directly beneath the existing tunnel, and has a vertical clearance of 10.6m. The specific implementation steps for the project's safety classification are as follows:

[0084] S1. The project involves the construction of a new parallel underpass tunnel within the subway protection zone. The classification method is as follows:

[0085] Let the center point of the existing subway tunnel cross-section be (x0, y0) and y0 > 0, then

[0086] when and The safety management level of the newly constructed parallel underpass tunnel project is Level 1.

[0087] when and or, and The safety management level of the newly constructed parallel underpass tunnel project is Level 2.

[0088] When (x0, y0) is outside the above range, the safety management level of the newly constructed parallel underpass tunnel project is level 3;

[0089] In the above formula, D is the outer diameter of the existing tunnel;

[0090] S2. Based on the geological survey report of the construction area, obtain the relevant soil layer parameters of the area including the existing subway tunnel and the new tunnel, as shown in Table 2;

[0091] Table 2 Relevant Soil Parameters for Newly Constructed Tunnels

[0092]

[0093] Based on the design data of the new tunnel and the existing tunnel, the height of the new tunnel is H = 6.2m, the half-span is b = 3.1m, the bottom of the tunnel is located in soil layer ⑩, and the internal friction angle is... The existing tunnel has an outer diameter D = 6.2m and a health status level of 1.

[0094] S3. Let the crown of the newly constructed tunnel be the origin, and the tunnel cross-section be the xOy plane, with the positive y-axis pointing vertically upwards and the x-axis pointing horizontally to the right. Calculate the outer boundary curve of the collapsed arch of the newly constructed tunnel, as shown in the following formula:

[0095] The half-span of the collapsed arch is:

[0096]

[0097] The height of the collapsed arch is:

[0098]

[0099] Where f is the rock firmness coefficient, which is taken as for loose rock, soil, and sandy soil. The formula for the outer boundary curve of the collapsed arch is:

[0100]

[0101] Given that the rectangular coordinates of the center of the existing subway tunnel cross-section are (x0, y0) = (0, 13.7), the calculation of the graded boundary is as follows:

[0102]

[0103] S4. Analysis shows that:

[0104]

[0105] The safety management level of the newly constructed parallel underpass tunnel project has been preliminarily determined to be Level 1.

[0106] S5. The existing subway tunnel has a health status level of 1, and the safety management level of the newly built parallel underpass tunnel project is determined to be 1.

[0107] 3. Reference Figure 4 A project involves constructing a new tunnel that vertically passes above an existing subway tunnel. The existing subway tunnel has a diameter of 6.2m and a center depth of 18m. The new tunnel has an outer diameter of 5m, is located above the existing subway tunnel, and has a vertical clearance of 5.5m between them. The specific implementation steps for the project's safety classification are as follows:

[0108] S1. The project involves the construction of a new vertical overpass tunnel within a subway protection zone. The classification method is as follows:

[0109] When s≥20mm, the safety management level of the newly built vertical overpass tunnel project is Level 1;

[0110] When 10mm≤s<20mm, the safety management level of the newly built vertical overpass tunnel project is Level 2;

[0111] When 0 < s < 10 mm, the safety management level of the newly built vertical overpass tunnel project is level 3;

[0112] In the formula, s is the amount of soil deformation above the existing tunnel caused by the construction of the new tunnel;

[0113] S2. According to the geological survey report of the construction area, the soil layer beneath the new tunnel is strongly weathered granite, therefore α can be taken as 0.084; based on the design data of the new tunnel and the existing tunnel, relevant tunnel structural parameters are obtained: the outer diameter of the new tunnel is d = 5m, the net distance between the new tunnel and the existing tunnel is l = 5.5m, and the control value of the excavation loss rate V for the new tunnel is... l =1%, the existing tunnel's health status level is 2;

[0114] S3. Calculate the soil deformation above the existing tunnel caused by the construction of a new tunnel:

[0115]

[0116] In the formula, d is the outer diameter of the new tunnel, l is the net distance between the new tunnel and the existing tunnel, and V l α is the formation loss rate, and α is a constant related to the formation properties, which can be taken as 0.084 for strongly weathered granite formations.

[0117] S4. Analysis shows that: 0 < s < 10 mm

[0118] The safety management level of the newly constructed vertical overpass tunnel project has been preliminarily determined to be Level 3.

[0119] S5. The existing subway tunnel is classified as Level 2 in terms of health status. Therefore, the final safety management level of the newly constructed vertical overpass tunnel project is determined to be Level 2.

[0120] 4. Reference Figure 5 A project plans to install an earth mound directly above an existing subway tunnel. The existing subway tunnel has a diameter of 6.2m and a center depth of 12m. The earth mound is located directly above the tunnel, occupying a length of 10m along the tunnel's longitudinal direction and a length of 10m perpendicular to the tunnel. The total weight of the earth mound is 2000kN. The specific implementation steps for the project's safety classification are as follows:

[0121] S1. The classification method for the surcharge works above the subway tunnel protection zone is determined as follows:

[0122] when At that time, the safety management level of the overhead loading project was Level 1;

[0123] when At that time, the safety management level of the overhead loading project was Level 2;

[0124] when At that time, the safety management level of the overhead loading project was level 3;

[0125] In the formula, H is the burial depth of the tunnel apex, b is the length of the uniformly distributed load in the plane containing the tunnel cross-section, and p is the magnitude of the uniformly distributed load. The pressure diffusion angle of the surrounding rock is taken as 22°.

[0126] S2. Based on the geological survey report of the construction area, obtain relevant surrounding rock parameters for the area including the existing subway tunnel and the loading range, simplifying it to a uniform soil layer, and taking the foundation surrounding rock pressure diffusion angle as [value missing]. Based on the design data of the new and existing tunnels, relevant tunnel structural parameters were obtained. The outer diameter of the existing tunnel is D = 6.2m, the burial depth of the tunnel top from the ground is H = 8.9m, and the health status level is 2.

[0127] S3. Considering the distribution of the load above in a plane perpendicular to the existing tunnel, analyze the plane where the tunnel cross-section is located, simplify the soil pile into a strip uniformly distributed load p = 20 kN / m with a unit width and length b = 10 m. Calculate the graded boundary as follows:

[0128]

[0129]

[0130] S4. Analysis shows that:

[0131]

[0132] The safety management level of the overhead loading project has been preliminarily determined to be Level 2.

[0133] S5. The existing subway tunnel is in a health condition of Level 2, and the final safety management level of the overhead ballast project is determined to be Level 1.

[0134] 5. Reference Figure 6 A project involves excavating and unloading soil directly above an existing subway tunnel. The existing subway tunnel has a diameter of 6.2m and a top burial depth of 12m. The excavation site is located directly above the tunnel, occupying 5m of land longitudinally and 10m of land perpendicular to the tunnel, with an excavation depth of 2m. The total weight of the excavated soil pile is 2000kN. The specific implementation steps for the project's safety classification are as follows:

[0135] S1. The classification method for the unloading project above the subway tunnel protection zone is determined as follows:

[0136] Calculate the relationship between the angle between the tunnel top and the lines connecting the two ends of the excavation pit and the stress.

[0137] when At that time, the safety management level of the unloading project above was Level 1;

[0138] when At that time, the safety management level of the unloading project above was Level 2;

[0139] when At that time, the safety management level of the unloading project above was level 3;

[0140] S2. Based on the geological survey report of the construction area, the surrounding rock of the existing tunnel is simplified to uniformly distributed surrounding rock; based on the design data of the new tunnel and the existing tunnel, relevant tunnel structural parameters are obtained. The outer diameter of the existing tunnel is D = 6.2m, the burial depth of the tunnel top from the ground at the excavation site is H = 10m, and the health status level is 3.

[0141] S3. Considering the distribution of the unloading above in a plane perpendicular to the existing tunnel, analyze the plane where the tunnel cross-section is located. Simplify the unloading project into a uniformly distributed vertical upward load p = 40 kN / m in a strip with a unit width and length b = 10 m. Calculate the angle β = 53.1° between the tunnel apex and the lines connecting the two ends of the pit. Calculate the graded boundary as follows:

[0142] β + sinβ = 1.73

[0143]

[0144]

[0145] S4. Analysis shows that:

[0146]

[0147] The safety management level of the unloading project above has been preliminarily determined to be Level 1.

[0148] S5. The existing subway tunnel is in a health condition of level 3, and the final safety management level of the unloading project above it is determined to be level 1.

Claims

1. A method for classifying engineering activities in a subway tunnel protection zone, characterized in that: Includes the following steps: S1. Establish a standard for delineating the safety protection zone of subway tunnels based on the degree of impact of each type of engineering activity on the safety of adjacent subway tunnels; S2. Obtain relevant structural parameters of existing subway tunnels and external construction projects, geological parameters of the construction area, and health status level of existing subway tunnels; S3. Determine the type of engineering activity and delineate the boundaries of its protected area; S4. Analyze the relationship between the tunnel location and protection zones of various levels to preliminarily determine the project's safety management level; S5. Based on the existing health status level of the subway tunnel, determine the final project safety management level: If the existing subway tunnel has a health status level of 1, the project safety management level remains unchanged; If the existing subway tunnel health status level is level 2, the project safety management level will be upgraded from level 3 to level 2, and level 2 will be upgraded to level 1. If the existing subway tunnel has a health status level of 3, then the project safety management level will be ultimately determined to be level 1. The engineering activities include single-sided foundation pit engineering, construction of a new parallel underpass tunnel or construction of a new vertical overpass tunnel, overhead loading engineering or overhead unloading engineering. The specific classification method for the single-sided foundation pit project is as follows: If the safety management level of the single-sided foundation pit project is Level 1, then... Then the safety management level of the single-sided foundation pit project is level 2. Therefore, the safety management level of this unilateral foundation pit project is Level 3. In the above formula, B The distance between the boundary of the adjacent foundation pit and the centerline of the existing subway tunnel. The outer diameter of the existing subway tunnel. The depth of the existing subway tunnel, This refers to the depth of the foundation pit excavation. The depth of the bottom of the diaphragm wall. α 1 The angle of fracture of the surrounding rock at the bottom of the foundation pit. α 2 The angle of fracture of the surrounding rock at the bottom of the diaphragm wall. Through formula calculate, The internal friction angle of the surrounding rock at the bottom of the foundation pit or the bottom of the underground continuous wall; The specific classification method for the newly constructed parallel underpass tunnel project is as follows: (1) Considering the construction condition where a collapse arch can form above the newly built tunnel, let the crown of the new tunnel arch be the origin, the tunnel cross-section be the xOy plane, the positive y-axis be vertically upward, and the x-axis be horizontally to the right. The center point of the existing subway tunnel cross-section is... and Then when and The safety management level of the newly constructed parallel underpass tunnel project is Level 1; when and ,or, ,and The safety management level of the newly constructed parallel underpass tunnel project is Level 2; when Outside the aforementioned scope, the safety management level for newly constructed parallel underpass tunnel projects is Level 3; In the above formula, D The outer diameter of the existing tunnel, For the half-span of the collapsed arch of the newly built tunnel, The height of the collapsed arch. b For the construction of a new tunnel half span, The height of the newly built tunnel, The internal friction angle of the tunnel surrounding rock; (2) When a collapse arch cannot be formed above the newly constructed tunnel, the specific classification method for the newly constructed parallel underpass tunnel project is as follows: Let the crown of the new tunnel be the origin, the tunnel cross-section be the xOy plane, the positive y-axis be vertically upward, and the x-axis be horizontally to the right. The center point of the existing subway tunnel cross-section is... and Then when At that time, the safety management level of the newly constructed parallel underpass tunnel project was Level 1; when At that time, the safety management level of the newly constructed parallel underpass tunnel project was Level 2; when Outside the aforementioned scope, the safety management level for newly constructed parallel underpass tunnel projects is Level 3; In the above formula, D The outer diameter of the existing tunnel, b For the construction of a new tunnel half span, H The height of the newly built tunnel, The internal friction angle of the surrounding rock at the bottom of the newly constructed tunnel; The specific classification method for the newly constructed vertical overpass tunnel project is as follows: when When the diameter is mm, the safety management level of the newly built vertical overpass tunnel project is Level 1; when At that time, the safety management level of the newly built vertical overpass tunnel project was Level 2; when When the diameter is mm, the safety management level of the newly built vertical overpass tunnel project is level 3; In the formula, s This refers to the deformation of the soil above the existing tunnel caused by the construction of a new tunnel. Furthermore, the aforementioned s It can be estimated using the following formula: In the formula, d The outer diameter of the newly constructed tunnel, in meters. The net distance between the newly constructed tunnel and the existing tunnel, in meters. This refers to the control value for the ground loss rate during the excavation of a newly constructed tunnel. This is a constant related to the stratigraphic properties; for strongly weathered granite strata, it can be taken as 0.

084. The specific method for classifying the above-ground loading project is as follows: when At that time, the safety management level of the overhead loading project was Level 1; when At that time, the safety management level of the overhead loading project was Level 2; when At that time, the safety management level of the overhead loading project was level 3; In the formula, H The depth of the tunnel apex. b The length of the uniformly distributed load within the plane containing the tunnel cross-section. p For the magnitude of a uniformly distributed load, The pressure diffusion angle of the foundation surrounding rock; The specific hierarchical method for the above-mentioned unloading project is as follows: when At that time, the safety management level of the unloading project above was Level 1; when At that time, the safety management level of the unloading project above was Level 2; when At that time, the safety management level of the unloading project above was level 3; In the formula, The angle between the lines connecting the tunnel apex and the two ends of the excavation pit. p This represents the unloading size within the plane containing the tunnel cross-section.

2. The method for classifying engineering activities in a subway tunnel protection zone according to claim 1, characterized in that, The geological parameters of the construction area include the thickness of each soil layer, the internal friction angle, and the elastic modulus; the relevant structural parameters include the existing tunnel structure dimensions, the elastic modulus of the segment lining, the structural dimensions of the new project, material parameters, and the control value of the ground loss rate during the excavation of the new tunnel. .

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