A method for determining the safe thickness of a tunnel in a deep, water-rich fault zone and its test assembly

Abstract

The present invention provides a method for determining the safe thickness of a deep-buried, water-rich fault-broken zone tunnel against sudden changes and a test component thereof, including a test component, wherein the test component consists of a test box, a ground stress loading system, a water supply system, and a monitoring system. The test box is filled with ordinary surrounding rock and constructed with surrounding rock of a fault-broken zone, and high ground stress is loaded on the test box, and then tunnel excavation is performed. When the value calculated by the detection data is greater than the safety limit, tunnel excavation is stopped. At this time, the safe thickness of sudden changes recorded at the excavation distance of the tunnel face is the difference between the distance between the middle of the face and the fault plane before tunnel excavation and the distance of the tunnel face that has been excavated. Then, the specific value of the safety limit is obtained by weighted averaging the detection data, and the sudden change point can be intuitively obtained, thereby deducing the distance of the tunnel that has been excavated, and then directly obtaining the sudden change safety thickness, which is finally embodied in digital form, so that the sudden change safety thickness is directly quantified, and it is convenient to accurately know the sudden change safety thickness.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel safety judgment, and in particular to a method for judging the safety thickness of a tunnel in a deep-buried, water-rich fault fracture zone and a test component thereof. Background Art

[0002] Since the southwest region is mountainous and has undulating terrain, most of the routes will pass through mountain tunnels. In addition, the southwest region has abundant underground karst water, and unfavorable geological conditions such as fault fracture zones are often encountered during tunnel excavation. The rock mass in the fault fracture zone is broken, groundwater is developed, and the stability is low. When the tunnel is excavated to this area, the surrounding rock stress field and seepage field are redistributed under the disturbance of construction. Under the action of rock mass stress and seepage pressure, water gushing and mud instability will occur, which will seriously threaten the safety of construction personnel, cause property losses and delay the construction period.

[0003] During the excavation of the tunnel from the ordinary surrounding rock section to the fault fracture zone, the surrounding rock deterioration degree gradually increases, and the length of the anti-burst rock mass between the tunnel face and the fault surface gradually decreases. Under the fluid-solid coupling effect of the fault fracture zone, the anti-burst rock mass is very likely to be sheared and unstable, resulting in a large amount of mud and sand from the fault fracture zone pouring into the tunnel. Therefore, before the tunnel is excavated to the fault fracture zone, it is necessary to determine the anti-burst safety thickness in advance and reserve enough anti-burst rock mass in front of the face to ensure the safety of tunnel excavation.

[0004] Application No. 2016101444691 provides a tunnel water inrush model test system and method under high ground stress and high seepage pressure. The test model is excavated at the reserved tunnel entrance, and the strain, pressure and displacement are monitored during the test through a monitoring and control system.

[0005] This existing technology monitors the face by direct detection, so this monitoring method is carried out synchronously with the progress of tunnel excavation. It is impossible to predict at what distance from the tunnel excavation to the broken fault zone that water and mud bursts will occur, that is, the safe thickness to prevent water and mud bursts cannot be assessed, so preventive excavation for water and mud bursts cannot be carried out. Only when the face reaches the limit of water and mud bursts will there be detection data. Summary of the invention

[0006] The purpose of the present invention is to provide a method for determining the safe thickness of a tunnel in a deep-buried, water-rich fault fracture zone and a test assembly thereof, so as to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for determining the safe thickness of a deep-buried, water-rich fault fracture zone tunnel for preventing sudden outbursts comprises a test assembly, wherein the test assembly comprises a test box, a ground stress loading system, a water supply system and a monitoring system, and the determination method comprises the following steps:

[0009] S1, fill the test box with ordinary surrounding rock and construct the surrounding rock of the fault fracture zone, and bury the water outlet components of the water supply system inside the surrounding rock of the fault fracture zone;

[0010] S2, high ground stress is applied to the test box through the ground stress loading system, and then the tunnel is excavated in sections, and the distance of tunnel excavation is recorded at all times;

[0011] S3, when the change rate of two consecutive monitoring curve data after the tunnel is excavated to a certain distance is greater than the safety limit, this point is regarded as the mutation inflection point. The specific expression is as follows:

[0012]

[0013] Where: x i is the monitoring data at the target distance, x i+1 、x i+2 Two consecutive monitoring data after the target distance, x i-1 is the last monitoring data of the target distance, [X] is the safety limit value, and the value may be different in different test schemes. In this test scheme, [X] = 25%;

[0014] Then, when the value calculated by the detection data is greater than the safety limit [X], stop tunnel excavation and record the tunnel face excavation distance;

[0015] S4, determine the tunnel anti-burst thickness:

[0016] S=YD

[0017] Where: S is the critical safety thickness of the tunnel for preventing sudden outbursts, Y is the distance between the middle of the tunnel face and the fault plane before tunnel excavation, and D is the excavated distance of the tunnel face.

[0018] Preferably, in said S1, when filling the test box with ordinary surrounding rock and constructing the surrounding rock of the fault fracture zone, the distance between the middle of the tunnel face to be excavated and the fault surface is recorded.

[0019] Preferably, in S3, x i The monitoring data at the target distance is used by the monitoring system to detect whether there is sudden water or mud on the face. The monitoring system will record the detection data and then calculate the safety limit value [X] based on the monitoring data.

[0020] Preferably, the ground stress loading system includes a reaction frame, a pressure-dividing steel plate, a hydraulic rod and a pressure sensor I. The reaction frame is arranged on the outside of the test box, and the pressure-dividing steel plate fits in the rectangular opening groove on the top of the test box. The hydraulic rod is arranged on the reaction frame, and a pressure sensor I is provided at its power output end, and the pressure sensor I is attached to the pressure-dividing steel plate.

[0021] Preferably, the water supply system comprises a water tank and a diversion water pipe, the diversion water pipe is pre-buried in the surrounding rock of the broken zone, and the diversion water pipe is connected to the water tank through a booster water pump.

[0022] Preferably, the monitoring system includes a laser rangefinder and a data acquisition instrument. The laser rangefinder is arranged outside the test box and facing the tunnel face. The laser rangefinder is electrically connected to the data acquisition instrument, and the data acquisition instrument is used to record the test data.

[0023] Preferably, the monitoring system includes a collection bucket, a pressure sensor II and a data acquisition instrument. The collection bucket is attached to the test box near the tunnel exit. A pressure sensor II is provided at the bottom of the collection bucket, and the pressure sensor II is electrically connected to the data acquisition instrument. The data acquisition instrument is used to record the test data.

[0024] Preferably, the monitoring system includes a water pressure gauge and a data acquisition instrument. The water pressure gauge is pre-buried at the junction of ordinary surrounding rock and surrounding rock of constructed fault fracture zone. The water pressure gauge is electrically connected to the data acquisition instrument, and the data acquisition instrument is used to record test data.

[0025] Preferably, the diversion water pipe pre-buried in the surrounding rock of the broken zone is provided with a water outlet hole, and the position with the water outlet hole is wrapped with gauze.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention obtains the specific numerical value of the safety limit through weighted averaging of the detection data, so the anti-burst inflection point can be obtained intuitively, thereby deducing the distance that the tunnel has been excavated, and then directly obtaining the anti-burst safety thickness, and finally expressing the anti-burst safety thickness in digital form, so that the anti-burst safety thickness can be directly quantified, which is convenient for accurately knowing the anti-burst thickness and increasing the safety and reliability during tunnel excavation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 is a schematic diagram of the test chamber and monitoring system;

[0030] Figure 3 is a schematic diagram of a water diversion pipe in the present invention;

[0031] Figure 4 A schematic diagram of monitoring data mutation;

[0032] In the figure: 1 test box, 2 reaction frame, 31 pressure dividing steel plate, 32 hydraulic rod, 33 pressure sensor I, 41 water tank, 42 ​​diversion pipe, 421 gauze, 5 water pressure gauge, 51 laser rangefinder, 52 collection bucket, 53 pressure sensor II, 54 data acquisition instrument. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example:

[0035] See also Figures 1 to 3 , the present invention provides a technical solution:

[0036] A method for determining the safe thickness of a tunnel in a deep-buried, water-rich fault zone, comprising a test assembly, wherein the test assembly is composed of a test box 1, a ground stress loading system, a water supply system and a monitoring system;

[0037] As a preferred embodiment, the ground stress loading system includes a reaction frame 2, a pressure-dividing steel plate 31, a hydraulic rod 32 and a pressure sensor Ⅰ33. The reaction frame 2 is arranged on the outside of the test box 1, and the reaction frame 2 is fixed to the ground by bolts. The pressure-dividing steel plate 31 fits in the rectangular opening groove on the top of the test box 1, wherein the pressure-dividing steel plate 31 forms a moving pair in the vertical direction of the test box 1. The hydraulic rod 32 is arranged on the reaction frame 2, and a pressure sensor Ⅰ33 is provided at its power output end, and the pressure sensor Ⅰ33 is attached to the pressure-dividing steel plate 31, so that normal pressure is applied to the pressure-dividing steel plate 31 through the hydraulic rod 32.

[0038] As a preferred embodiment, the water supply system includes a water tank 41 and a diversion water pipe 42. The diversion water pipe 42 is pre-buried in the surrounding rock of the broken zone, and the diversion water pipe 42 is connected to the water tank 41 through a booster water pump. Then, the water in the water tank 41 will flow into the surrounding rock of the broken zone through the diversion water pipe 42, thereby simulating the water inrush condition.

[0039] As a preferred embodiment, the monitoring system includes a laser rangefinder 51 and a data acquisition instrument 54. The laser rangefinder 51 is arranged on the outside of the test box 1 and faces the tunnel face. The laser rangefinder 51 is electrically connected to the data acquisition instrument 54. The data acquisition instrument 54 is used to record test data. Then, by facing the laser rangefinder 51 to the tunnel tunnel face, when the tunnel face is displaced, the laser rangefinder 51 will feedback the displacement, thereby realizing the detection of whether the tunnel face is stable.

[0040] As a preferred embodiment, the monitoring system includes a collecting barrel 52, a pressure sensor II53 and a data acquisition instrument 54. The collecting barrel 52 is attached to the test box 1 near the tunnel exit. When water and mud gush out from the tunnel, the water and mud will seep into the collecting barrel 52, thereby detecting the amount of water and mud gush out. A pressure sensor II53 is provided at the bottom of the collecting barrel 52. The amount of water and mud gush out from the collecting barrel 52 is detected by the pressure sensor II53, and the pressure sensor II53 is electrically connected to the data acquisition instrument 54, which is used to record the test data.

[0041] As a preferred embodiment, the monitoring system includes a water pressure gauge 5 and a data acquisition instrument 54. The water pressure gauge 5 is pre-buried at the junction of ordinary surrounding rock and surrounding rock of constructed fault fracture zone. Then, when sudden water and mud occur, the water pressure gauge 5 will detect the pressure difference in the first time, thereby achieving the detection effect. The water pressure gauge 5 is electrically connected to the data acquisition instrument 54, and the data acquisition instrument 54 is used to record test data.

[0042] As a preferred embodiment, the water pressure meter 5, the laser rangefinder 51, the collection bucket 52, the pressure sensor II53 and the data acquisition instrument 54 are used together, so that the data acquisition instrument 54 can collect multiple sets of data, and then can detect through multiple sets of data, thereby ensuring the accuracy of the detection.

[0043] As a preferred embodiment, the data acquisition instrument 54 is provided with a display screen, which can intuitively obtain the test data.

[0044] As a preferred embodiment, the diversion water pipe 42 pre-buried in the surrounding rock of the broken zone is provided with a water outlet, and the position with the water outlet is wrapped with gauze 421 to avoid clogging the water outlet.

[0045] A method for determining the safe thickness of a tunnel in a deep-buried, water-rich fault zone to prevent sudden outbursts comprises the following steps:

[0046] S1, fill the test box 1 with ordinary surrounding rock and construct the surrounding rock of the fault fracture zone, bury the water outlet component of the water supply system inside the test box 1 when constructing the surrounding rock of the fault fracture zone; when filling the test box 1 with ordinary surrounding rock and constructing the surrounding rock of the fault fracture zone, record the distance between the middle of the tunnel face to be excavated and the fault surface;

[0047] S2, high ground stress is applied to the test box 1 through the ground stress loading system, and then the tunnel is excavated in sections, and the distance of tunnel excavation is recorded at all times;

[0048] S3, when the change rate of two consecutive monitoring curve data after the tunnel is excavated to a certain distance is greater than the safety limit, this point is regarded as the mutation inflection point. The specific expression is as follows:

[0049]

[0050] Where: x i is the monitoring data at the target distance, x i+1 、x i+2 Two consecutive monitoring data after the target distance, x i-1 is the last monitoring data of the target distance, [X] is the safety limit value, and the value may be different in different test schemes. In this test scheme, [X] = 25%;

[0051] Then, when the value calculated by the detection data is greater than the safety limit [X], stop tunnel excavation and record the tunnel face excavation distance; x i The monitoring data at the target distance is the monitoring system's detection of whether there is water or mud inrush at the tunnel face. The monitoring system will record the detection data and then calculate the safety limit value [X] based on the monitoring data. i In fact, the Figure 4 The specific value of the vertical coordinate in the monitoring system is the data recorded by the monitoring system, such as the displacement obtained by the laser rangefinder 51, the water and mud inflow obtained by the pressure sensor II53, and the water pressure difference obtained by the water pressure gauge 5. i It can be any of the above data or the data obtained after comprehensive evaluation of the three data, where x i The numerical units are unified units.

[0052] S4, determine the tunnel anti-burst thickness:

[0053] S=YD

[0054] In the formula, S is the critical safety thickness of the tunnel for preventing sudden outbursts, Y is the distance between the middle of the tunnel face and the fault plane before tunnel excavation, and D is the excavated distance of the tunnel face. The value of Y in the formula has been determined in S1, and D is the additional Figure 4 The value recorded on the horizontal axis in , where D has been recorded in S2. Then the value of the critical safety thickness S of the tunnel can be directly obtained, so that the critical safety thickness of the tunnel can be directly quantified.

[0055] As a preferred embodiment, 40-70 mesh quartz sand is selected as the coarse aggregate of similar materials, barite powder is used as the fine aggregate, gypsum, clay and cement are used as binders, and the proportions of similar materials of ordinary surrounding rock and fault fracture zone surrounding rock that meet the test requirements are determined, as shown in Table 1 and Table 2 respectively.

[0056] Table 1 Proportion of similar materials for common surrounding rocks

[0057] Material water plaster cement Quartz sand Barite powder Moisture content% Proportion 1 6.04 0.43 1.16 0.46 11

[0058] Table 2 Proportion of similar materials in surrounding rock of fault fracture zone

[0059] Material water Clay Quartz sand Barite powder Moisture content% Proportion 1 1.47 7.56 4.18 7.04

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for determining the safe thickness of a deep-buried, water-rich fault zone tunnel for preventing sudden outbursts, comprising a test assembly, wherein the test assembly consists of a test box (1), a ground stress loading system, a water supply system and a monitoring system, and is characterized in that: The determination method comprises the following steps: S1, filling the test box (1) with ordinary surrounding rock and constructing the surrounding rock of the fault fracture zone, and burying the water outlet component of the water supply system inside the surrounding rock of the fault fracture zone; S2, applying high ground stress to the test box (1) through a ground stress loading system, and then excavating the tunnel in sections, and recording the distance of tunnel excavation at all times; S3, when the change rate of two consecutive monitoring curve data after tunnel excavation to a certain distance is greater than the safety limit, this point is regarded as the mutation inflection point, and the mutation inflection point is the inflection point where the monitoring system detects whether water and mud inrush occurs at the tunnel face. The specific expression is as follows: Where: x i is the monitoring data at the target distance, where x i The monitoring data at the target distance is used by the monitoring system to detect whether there is water or mud inrush at the tunnel face. i+1 、x i+2 Two consecutive monitoring data after the target distance, x i-1 is the last monitoring data of the target distance, [X] is the safety limit value, and the value may be different in different test schemes. In this test scheme, [X] = 25%; Then, when the value calculated by the detection data is greater than the safety limit [X], stop tunnel excavation and record the tunnel face excavation distance; S4, determine the tunnel anti-burst thickness: S=YD Where: S is the critical safety thickness of the tunnel for preventing sudden outbursts, Y is the distance between the middle of the tunnel face and the fault plane before tunnel excavation, and D is the excavated distance of the tunnel face.

2. A method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to claim 1, characterized in that: In the S1, when ordinary surrounding rock is filled in the test box (1) and the surrounding rock of the fault fracture zone is constructed, the distance between the middle of the tunnel face to be excavated and the fault surface is recorded.

3. The method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to claim 1 is characterized in that: The S3x i The monitoring data at the target distance is used by the monitoring system to detect whether there is sudden water or mud on the face. The monitoring system will record the detection data and then calculate the safety limit value [X] based on the monitoring data.

4. A method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to any one of claims 1 to 3, characterized in that: The ground stress loading system comprises a reaction frame (2), a pressure dividing steel plate (31), a hydraulic rod (32) and a pressure sensor I (33); the reaction frame (2) is arranged on the outside of the test box (1); the pressure dividing steel plate (31) fits into a rectangular opening groove on the top of the test box (1); the hydraulic rod (32) is arranged on the reaction frame (2); a pressure sensor I (33) is arranged at its power output end; and the pressure sensor I (33) is attached to the pressure dividing steel plate (31).

5. A method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to any one of claims 1 to 3, characterized in that: The water supply system comprises a water tank (41) and a diversion water pipe (42); the diversion water pipe (42) is pre-buried in the surrounding rock of the fracture zone, and the diversion water pipe (42) is connected to the water tank (41) via a booster water pump.

6. A method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to any one of claims 1 to 3, characterized in that: The monitoring system comprises a laser rangefinder (51) and a data acquisition device (54). The laser rangefinder (51) is arranged outside the test box (1) and directly facing the tunnel face. The laser rangefinder (51) is electrically connected to the data acquisition device (54). The data acquisition device (54) is used to record test data.

7. A method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to any one of claims 1 to 3, characterized in that: The monitoring system comprises a collection bucket (52), a pressure sensor II (53) and a data acquisition instrument (54). The collection bucket (52) is attached to the test box (1) near the tunnel exit. The bottom of the collection bucket (52) is provided with a pressure sensor II (53). The pressure sensor II (53) is electrically connected to the data acquisition instrument (54). The data acquisition instrument (54) is used to record test data.

8. A method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to any one of claims 1 to 3, characterized in that: The monitoring system comprises a water pressure gauge (5) and a data acquisition instrument (54); the water pressure gauge (5) is pre-buried at the junction of ordinary surrounding rock and surrounding rock of a constructed fault fracture zone; the water pressure gauge (5) is electrically connected to the data acquisition instrument (54); and the data acquisition instrument (54) is used to record test data.

9. A method for determining the safe thickness of a deep buried water-rich fault zone tunnel for preventing sudden outbursts according to any one of claim 5, characterized in that: The diversion water pipe (42) pre-buried in the surrounding rock of the fracture zone is provided with a water outlet hole, and the position with the water outlet hole is wrapped with gauze (421).

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