CN116907362A - Method for judging anti-outburst safety thickness of tunnel of deep-buried water-rich fault fracture zone and test assembly thereof - Google Patents

Abstract

The invention provides a method for determining the anti-outburst safety thickness of a tunnel in a deep water-rich fault fracture zone and a test component thereof, which includes a test component. The test component is composed of a test box, a ground stress loading system, a water supply system and a monitoring system. The test box is filled with For ordinary surrounding rock and surrounding rock in the fault fracture zone, the test chamber is loaded with high ground stress, and then the tunnel is excavated. When the value calculated from the test data is greater than the safety limit, the tunnel excavation is stopped. At this time, the tunnel face excavation is recorded. The distance anti-outburst safety thickness is the difference between the distance between the middle part of the tunnel face and the fault plane before tunnel excavation and the excavated distance of the tunnel tunnel face. Then the weighted average of the detection data is used to obtain the specific value of the safety limit. Then the anti-outbreak inflection point can be intuitively obtained, thereby deducing the distance of the tunnel that has been excavated, and then directly obtaining the anti-outbreak safety thickness, which is finally reflected in the form of numbers. out, so that the anti-outbreak safety thickness can be directly quantified, making it easy to accurately know the anti-outbreak thickness.

Description

A method and test method for determining the safety thickness of tunnels in the broken zone of deep water-rich faults to prevent outbursts test component

Technical field

The invention relates to the technical field of tunnel safety judgment, specifically a method and test assembly for judging the anti-outburst safety thickness of tunnels in deep water-rich fault fracture zones.

Background technique

Since the southwest region is mountainous and the terrain is highly undulating, most lines will pass through mountain tunnels. In addition, the southwest region is rich in underground karst water. Unfavorable geology such as fault fracture zones will often be 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, under construction disturbance, the surrounding rock stress field and seepage field are redistributed. Under the action of rock mass stress and seepage pressure, there will be Water gushing and mud bursting can cause instability and damage, seriously threatening the safety of construction workers, causing property losses and delays in construction schedules.

During the tunnel excavation process from the ordinary surrounding rock section to the fault fracture zone, the degree of deterioration of the surrounding rock gradually increases, and the length of the anti-outburst rock mass between the tunnel face and the fault surface also gradually decreases. The fluid-solid coupling in the fault fracture zone Under the action, the anti-outburst rock mass is prone to shear instability, causing a large amount of mud and sand from the fault fracture zone to flow into the tunnel. Therefore, before the tunnel is excavated to the fault fracture zone, it is necessary to determine the safe anti-outburst thickness in advance and reserve sufficient anti-outburst rock mass in front of the tunnel face to ensure the safety of tunnel excavation.

The application number is 2016101444691, which provides a model test system and method for tunnel water inrush under high ground stress and high seepage pressure. The test model is excavated at the reserved tunnel opening, and the strain, pressure, and pressure during the test are measured through the monitoring and control system. Monitoring of displacement.

This existing technology monitors the tunnel face through direct detection. This monitoring method is carried out synchronously with the process of tunnel excavation, and it is impossible to predict the distance from tunnel excavation to the broken fault zone before an accident occurs. The situation of water and mud outbursts, that is, the safe anti-outburst thickness, cannot be assessed, so preventive excavation of water and mud outbursts cannot be carried out. Only when the tunnel face reaches the limit of water and mud outbursts will there be detection data.

Contents of the invention

The purpose of the present invention is to provide a method and test assembly for determining the anti-outburst safety thickness of tunnels with deep water-rich fault fracture zones, so as to solve the problems raised in the above background technology.

In order to achieve the above objects, the present invention provides the following technical solutions:

A method for determining the anti-outburst safety thickness of tunnels in deep water-rich fault fracture zones, including a test component, where the test component is composed of a test chamber, a ground stress loading system, a water supply system and a monitoring system. The determination method includes the following steps:

S1, fill the test box with ordinary surrounding rock and construct the surrounding rock of the fault fracture zone. When constructing the surrounding rock of the fault fracture zone, bury the water outlet component of the water supply system inside it;

S2, load the test chamber with high ground stress through the ground stress loading system, and then carry out segmented tunnel excavation, and record the tunnel excavation distance at all times;

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:

In the formula: _xi is the monitoring data at the target distance, xi ₊₁ and xi ₊₂ are the monitoring data for two consecutive times after the target distance, xi _-1 is the monitoring data before the target distance, [X] is the safety limit, This value may be different in different test plans. In this test plan, [X] = 25%;

Then stop excavation of the tunnel when the value calculated from the detection data is greater than the safety limit [X], and record the excavation distance of the tunnel face at this time;

S4, determine the anti-burst thickness of the tunnel as:

S＝Y-D

In the formula: S is the critical anti-outburst safety thickness of the tunnel, Y is the distance between the middle of the tunnel face and the fault plane before tunnel excavation, and D is the excavation distance of the tunnel face.

Preferably, in S1, when the test box is filled with ordinary surrounding rock and the surrounding rock of the fault fracture zone is constructed, the distance between the middle part of the tunnel face to be excavated and the fault surface is recorded.

Preferably, the monitoring data at the x _i target distance in S3 is for the monitoring system to detect whether water and mud inrush occur on the tunnel face. The monitoring system will record the detection data, and then calculate the safety limit [X] based on the monitoring data.

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 outside the test box, and the pressure dividing steel plate fits in the rectangular opening slot on the top of the test box. , the hydraulic rod is arranged on the reaction frame, and its power output end is equipped with a pressure sensor I, and the pressure sensor I is attached to the pressure dividing steel plate.

Preferably, the water supply system includes a water tank and a diverting water pipe, the diverting water pipe is embedded in the surrounding rock of the fracture zone, and the diverting water pipe is connected to the water tank through a booster water pump.

Preferably, the monitoring system includes a laser rangefinder and a data collector. The laser rangefinder is installed outside the test chamber and facing the tunnel face. The laser rangefinder is electrically connected to the data collector. , the data collector is used to record the test data.

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

Preferably, the monitoring system includes a water pressure gauge and a data acquisition instrument. The water pressure gauge is pre-embedded at the junction of ordinary surrounding rock and the surrounding rock in the construction fault fracture zone. The water pressure gauge and the data acquisition instrument are electrically connected. Connection, data acquisition instrument is used to record test data.

Preferably, the diversion water pipe embedded in the surrounding rock of the crushing zone is provided with a water outlet, and the position with the water outlet is wrapped with gauze.

Compared with the prior art, the beneficial effects of the present invention are:

This invention obtains the specific value of the safety limit by performing a weighted average of detection data, and then the anti-outbreak inflection point can be intuitively obtained, thereby deducing the distance of the tunnel that has been excavated, and then directly obtaining the anti-outbreak safety thickness, and finally in the form of a number It embodies the safe thickness against outburst and directly quantifies the safe thickness against outburst, making it easy to accurately know the anti-outburst thickness and increasing the safety and reliability during tunnel excavation.

Description of the drawings

Figure 1 is a schematic diagram of the overall structure of the present invention;

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

Figure 3 is a schematic diagram of the diverter water pipe in the present invention;

Figure 4 is a schematic diagram of monitoring data mutations;

In the picture: 1 test chamber, 2 reaction frame, 31 partial pressure steel plate, 32 hydraulic rod, 33 pressure sensor I, 41 water tank, 42 diverter water pipe, 421 gauze, 5 water pressure gauge, 51 laser range finder, 52 collection bucket , 53 pressure sensor II, 54 data acquisition instrument.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example:

Referring to Figures 1 to 3, the present invention provides a technical solution:

A method for determining the anti-outburst safety thickness of tunnels in deep water-rich fault fracture zones, including a test component, where the test component consists of a test chamber 1, a ground stress loading system, a water supply system and a monitoring system;

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 I 33. The reaction frame 2 is arranged outside the test chamber 1, and the reaction frame 2 is fixed on the test chamber 1 by bolts. On the ground, the pressure dividing steel plate 31 fits in the rectangular opening slot on the top of the test chamber 1. The pressure dividing steel plate 31 forms a moving pair in the vertical direction of the test chamber 1. The hydraulic rod 32 is set on the reaction frame 2, and its power The output end is provided with a pressure sensor I33, and the pressure sensor I33 is attached to the pressure dividing steel plate 31, so the hydraulic rod 32 applies normal pressure to the pressure dividing steel plate 31.

As a preferred embodiment, the water supply system includes a water tank 41 and a shunt water pipe 42. The shunt water pipe 42 is embedded in the surrounding rock of the crushing zone, and the shunt water pipe 42 is connected to the water tank 41 through a booster water pump. Then the water in the water tank 41 will pass through the shunt. The water pipe 42 flows into the surrounding rock of the fracture zone, thereby simulating water inrush conditions.

As a preferred embodiment, the monitoring system includes a laser rangefinder 51 and a data collector 54. The laser rangefinder 51 is arranged outside the test chamber 1 and faces the tunnel face. The laser rangefinder 51 and the data collector 54 Electrically connected, the data collector 54 is used to record the test data, then the laser rangefinder 51 is directed to the tunnel face. When the tunnel face is displaced, the laser rangefinder 51 will feedback the displacement, thereby realizing the detection of the tunnel face. Is the subsurface stable?

As a preferred embodiment, the monitoring system includes a collection bucket 52, a pressure sensor II53 and a data collector 54. The collection bucket 52 is attached to the test chamber 1 near the tunnel exit, so that when there is water and mud inside the tunnel, it will seep into the collection bucket. 52, and then detect the amount of water and mud. The bottom of the collection bucket 52 is provided with a pressure sensor II53. Then the pressure sensor II53 is used to detect the amount of water and mud in the collection bucket 52, and the pressure sensor II53 is electrically connected to the data collector 54. , the data collector 54 is used to record the test data.

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-embedded at the junction of ordinary surrounding rock and the surrounding rock in the construction fault fracture zone. Then, when water and mud inrush occur, the water pressure The meter 5 will detect the pressure difference immediately to achieve the detection effect. The water pressure meter 5 is electrically connected to the data acquisition instrument 54, and the data acquisition instrument 54 is used to record the test data.

As a preferred embodiment, the water pressure gauge 5, laser rangefinder 51, collection bucket 52, pressure sensor II53 and data collector 54 are used together, then the data collector 54 can collect multiple sets of data, and then can collect multiple sets of data. Detection ensures the accuracy of detection.

As a preferred embodiment, the data acquisition instrument 54 has a display screen, which can intuitively obtain test data.

As a preferred embodiment, the diversion water pipe 42 embedded in the surrounding rock of the crushing zone is provided with a water outlet, and the position with the water outlet is wrapped with gauze 421 to avoid blocking the water outlet.

A method for determining the safety thickness for outburst prevention of tunnels in deep water-rich fault fracture zones includes the following steps:

S1, the test box 1 is filled with ordinary surrounding rock and the surrounding rock of the fault fracture zone is constructed. When constructing the surrounding rock of the fault fracture zone, the water outlet component of the water supply system is buried inside it; the test box 1 is filled with ordinary surrounding rock and the fault fracture zone is constructed. When recording the surrounding rock in the fracture zone, record the distance between the middle part of the tunnel face to be excavated and the fault plane;

S2, load the test chamber 1 with high ground stress through the ground stress loading system, and then carry out segmented tunnel excavation, and record the tunnel excavation distance at all times;

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:

In the formula: _xi is the monitoring data at the target distance, xi ₊₁ and xi ₊₂ are the monitoring data for two consecutive times after the target distance, xi _-1 is the monitoring data before the target distance, [X] is the safety limit, This value may be different in different test plans. In this test plan, [X] = 25%;

Then when _the value calculated from the detection data is greater than the safety limit [X], the tunnel excavation is stopped, and the excavation distance of the tunnel face is recorded at this time; the monitoring data at the target distance of If water breaks out of mud, the monitoring system will record the detection data, and then calculate the safety limit [X] based on the monitoring data. In the formula, x _i is actually the ordinate in Figure 4, and its specific value is the data recorded by the monitoring system, such as the displacement obtained by the laser rangefinder 51, and the water and mud inrush obtained by the pressure sensor II53. The water pressure difference obtained by measuring and water pressure gauge 5, of course, x _i can be any of the above data or the data obtained after comprehensive evaluation of the three data, in which the numerical unit of x _i is a unified unit.

S4, determine the anti-burst thickness of the tunnel as:

S＝Y-D

In the formula: S is the critical anti-outburst safety thickness of the tunnel, Y is the distance between the middle of the tunnel face and the fault plane before tunnel excavation, and D is the excavation distance of the tunnel face. The value of Y in the formula has been determined in S1, and D is the value recorded on the abscissa in Figure 4, where D has been recorded in S2. Then the value of the tunnel's critical anti-outburst safety thickness S can be directly obtained, making the tunnel's critical anti-outbreak safety thickness directly quantified.

As a preferred embodiment, 40-70 mesh quartz sand was selected as the coarse aggregate of similar materials, barite powder was used as the fine aggregate, and gypsum, clay and cement were used as the cementing agent. The common surrounding rock and fault fracture zone that met the test requirements were determined. The proportions of similar materials in the surrounding rock are shown in Table 1 and Table 2 respectively.

Table 1 Ratio of similar materials to common surrounding rock

Material water plaster cement quartz sand barite powder Moisture content% Proportion 1 6.04 0.43 1.16 0.46 11

Table 2 The proportion of similar materials in the surrounding rock of the fault fracture zone

Material water Clay quartz sand barite powder Moisture content% Proportion 1 1.47 7.56 4.18 7.04

Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art will understand that various changes, modifications, and substitutions can be made to these embodiments without departing from the principles and spirit of the invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (9)

1. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone comprises 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 by comprising the following steps:

s1, filling common surrounding rock and constructing fault broken zone surrounding rock in a test box (1), and burying a water outlet component of a water supply system in the test box when constructing the fault broken zone surrounding rock;

s2, loading high ground stress on the test box (1) through a ground stress loading system, tunneling a tunnel in a sectional mode, and recording the tunnel excavation distance at any time;

s3, when the change rate of the continuous twice monitoring curve data after the tunnel is excavated to a certain distance is larger than a safety limit value, taking the point as a sudden change inflection point, wherein the specific expression is as follows:

wherein: x is x _i For monitoring data at target distance, x _i+1 、x _i+2 Monitoring data, x, two subsequent times after target distance _i-1 For the previous monitoring data of the target distance, [ X ]]For safety limits, the values may be different for different test protocols [ X ]]＝25％；

Stopping excavating the tunnel when the calculated value of the detection data is larger than a safety limit value [ X ], and recording the excavation distance of the tunnel face at the moment;

s4, determining the tunnel anti-burst thickness as follows:

S＝Y-D

wherein: s is critical anti-outburst safety thickness of the tunnel, Y is the distance between the middle part of the tunnel face and the fault plane before tunnel excavation, and D is the excavated distance of the tunnel face.

2. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to claim 1 is characterized by comprising the following steps of: in the step S1, the distance between the middle part of the tunnel face to be excavated and the fault plane is recorded when the test box (1) is filled with common surrounding rock and the fault broken zone surrounding rock is constructed.

3. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to claim 1 is characterized by comprising the following steps of: x in S3 _i The monitoring data at the target distance is a monitoring system for detecting whether water and mud burst occurs on the face, the monitoring system records the detection data, and then calculates a safety limit value [ X ] according to the monitoring data]。

4. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to any one of claims 1 to 3, which is 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), wherein the reaction frame (2) is arranged on the outer side of the test box (1), the pressure dividing steel plate (31) is fit in a rectangular open groove at the top of the test box (1), the hydraulic rod (32) is arranged on the reaction frame (2), the power output end of the hydraulic rod is provided with the pressure sensor I (33), and the pressure sensor I (33) is attached to the pressure dividing steel plate (31).

5. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to any one of claims 1 to 3, which is characterized in that: the water supply system comprises a water tank (41) and a diversion water pipe (42), wherein the diversion water pipe (42) is pre-buried in surrounding rock of the broken zone, and the diversion water pipe (42) is communicated with the water tank (41) through a booster water pump.

6. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to any one of claims 1 to 3, which is characterized in that: the monitoring system comprises a laser range finder (51) and a data acquisition instrument (54), wherein the laser range finder (51) is arranged on the outer side of the test box (1) and faces the face, the laser range finder (51) is electrically connected with the data acquisition instrument (54), and the data acquisition instrument (54) is used for recording test data.

7. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to any one of claims 1 to 3, which is characterized in that: the monitoring system comprises a collecting barrel (52), a pressure sensor II (53) and a data acquisition instrument (54), wherein the collecting barrel (52) is attached to the test box (1) and close to the tunnel outlet, the pressure sensor II (53) is arranged at the bottom of the collecting barrel (52), the pressure sensor II (53) is electrically connected with the data acquisition instrument (54), and the data acquisition instrument (54) is used for recording test data.

8. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to any one of claims 1 to 3, which is characterized in that: the monitoring system comprises a water pressure gauge (5) and a data acquisition instrument (54), wherein the water pressure gauge (5) is pre-buried at the junction of a common surrounding rock and a constructed fault fracture zone surrounding rock, the water pressure gauge (5) is electrically connected with the data acquisition instrument (54), and the data acquisition instrument (54) is used for recording test data.

9. The method for judging the anti-outburst safety thickness of the tunnel of the deep-buried water-rich fault fracture zone according to any one of claim 5, which is characterized in that: the split water pipe (42) pre-buried in the broken belt surrounding rock is provided with a water outlet, and gauze (421) is wound at the position with the water outlet.