JP2023516230A - Method for monitoring and supporting mining tunnel host rock - Google Patents

Abstract

A method for monitoring and supporting mining tunnel host rock. A method for monitoring and supporting a mining tunnel host rock, the method continuously monitoring host rock strain in response to a distributed optical fiber (29) monitoring frequency, and generating host rock strain monitoring data. and the host rock strain data obtained by interpolating the host rock strain monitoring data, the tunnel (1) is divided into regions, and the load bearing regions at different positions of the tunnel and the different obtaining the size of the fracture area in the section and depending on the relationship between host rock stress and strain, based on the host rock strain data, the load-bearing area at different locations in the gallery and the size of the fracture area in different sections of the gallery; and determining the timing and method of primary shoring, secondary shoring and reinforcement of host rock. The method is to support the host rocks in various stable states during the excavation process, respectively, and provide reinforcement support to the areas where the degree of fracturing increases obviously during the mining process, thereby avoiding the late deformation problem of the tunnel (1). is eliminated, and the stability and safety of the tunnel (1) are significantly improved. [Selection diagram] Fig. 1

Description

The present application relates to the technical field of tunnel host rock monitoring and support, and more particularly to mining tunnel host rock monitoring and supporting methods.

In China, most of the well shafts belong to the shafts with medium and large loose areas, where the bulking force of the host rock is obvious in the shafts with medium loose areas, and the bulking force of the host rock is The deformation is large and cracks or other fracture phenomena occur, the lithology of the host rock in the deep tunnel is different, the distribution of the geological stress is complicated, and it is difficult to analyze the conventional rock elastoplastic mechanics theory. , which increases the difficulty of studying structural instability mechanisms in deep tunnels.

Due to empirically designed support means, it is not possible to precisely position the extent of the fracture zone and the stability of the deep tunnel is difficult to manage, which makes maintenance of the deep tunnel very difficult. In addition, clarifying the host rock load acting on the tunnel support system is a prerequisite for designing and constructing each support layer, and is also a difficult point. In the method of determining the parameters of the relevant shoring zone layers by experience during actual construction, the control index is usually the deformation, which substantially depends on the complexity of the host rock itself and the spatio-temporal lack of the construction process. It is difficult to obtain host rock loads directly due to its nature, but to monitor deformation relatively accurately. At present, for the support design of deep rock tunnels, the conventional method adopts the combined support method of “anchoring-coating-injection-fastening-injection”, and the spacing and row for anchor rods, anchor cable supports. The interval is shortened, and the shoring only considers the effect of concentration of tangential stress on the host rock. After excavation, the strength deterioration of the host rock, the shear stress distribution, etc. are not taken into account. , the late deformation is serious and the cross-sectional shrinkage is large, so it is difficult to solve the problem of structural instability of deep tunnels. In order to grasp the structural instability mechanism of deep tunnels, the structural support means with reasonable design, the initial support effect of deep tunnels is often unfavorable. The repair rate is high, and it becomes unusable for a long time, which brings huge economic loss and hidden dangers to safety production for deep mining.

SUMMARY OF THE INVENTION It is an object of the present application to provide a method for monitoring and supporting mining driveway host rocks to overcome or mitigate the problems present in the above-described prior art.

To achieve the above objectives, the present application provides the following technical solutions.

The present application provides a method of monitoring and supporting a mining tunnel host rock including the following steps.

Step S10, a step of continuously monitoring the strain of the mother rock according to the monitoring frequency of the distributed optical fiber to obtain the mother rock strain monitoring data, specifically, in a preset time period, the the distributed optical fiber continuously monitors the host rock distortion, determines a monitoring frequency of the distributed optical fiber,
The distributed optical fiber periodically and continuously monitors the host rock strain according to the monitoring frequency to obtain the host rock strain monitoring data.

Step S20: Based on the host rock distortion data obtained by interpolating the host rock distortion monitoring data, the tunnel is divided into areas, and the load bearing areas at different positions of the tunnel and the crushing areas at different sections of the tunnel. Obtaining the magnitude of, specifically:
Interpolating the host rock strain monitoring data along the radial direction and running direction of the tunnel, respectively, and correspondingly obtaining the host rock strain data along the radial direction and running direction of the tunnel,
Based on the host rock strain data along the radial direction and the direction of travel of the gallery, correspondingly determining the size of the load-bearing areas at different locations of the gallery and the fracture areas at different sections of the gallery.

Step S30, according to the relationship between host rock stress and strain, according to the host rock strain data, the load-bearing areas at different positions of the tunnel and the size of fractured areas at different sections of the tunnel; Determine the timing and method of primary support, secondary support and reinforcement.

(beneficial effect)

In the present application, host rock strain is continuously monitored according to the monitoring frequency of the distributed optical fiber, host rock strain monitoring data is obtained, and the host rock strain monitoring data is interpolated to obtain host rock strain data. Based on this, the tunnel is divided into areas to obtain the size of the load-bearing area at different positions of the tunnel and the fracture area in different sections of the tunnel, and according to the relationship between host rock stress and strain, the host Based on the rock strain data, the size of the load-bearing areas at different positions in the tunnel and the fracture areas in different sections of the tunnel, the timing and treatment methods of the primary support, secondary support and reinforcement treatment of the host rock are determined.

According to the monitoring frequency of the distributed optical fiber, the present application continuously monitors the distortion of the host rock, timely grasps the deformation of the host rock and the state of receiving force at each time, and the tunnel tunnel based on the monitored data. By determining the timing of primary support, secondary support and reinforcement treatment, supporting the host rocks in different stable states, and reinforcing the areas where the degree of crushing obviously increases during the mining process, The late deformation problem is eliminated, and the stability and safety of the tunnel are significantly improved.

The mining tunnel host rock monitoring and supporting method provided by the present application employs distributed optical fiber sensing technology to monitor different locations in the gallery and different depths of the host rock according to the Brillouin frequency shift and strain relationship of the distributed optical fiber. By continuously monitoring strain at depth, data is more accurately and easily obtained, and fiber optic sensing can operate successfully under harsh or extreme conditions and is less affected by the mine shaft environment.

A method for monitoring and supporting a mining tunnel host rock provided by the present application comprises: interpolating host rock distortion data obtained by monitoring distributed optical fibers; A region segmentation is performed on it to obtain the size of the load-bearing regions at different locations in the gallery and the fracture regions in different sections of the gallery. Compared to conventional data processing methods, this method is simpler and more accurate, and the visualized images can be used to intuitively and quickly observe the state of rock fragmentation in each area of the tunnel. .

A mining tunnel host rock monitoring and supporting method provided by the present application provides optimal support for primary and secondary support based on host rock strain data obtained from continuous distributed fiber optic monitoring. Specific timing is determined, support is provided according to the determined support timing, and the deformation state of the crushing area and the stress relaxation state of the plastic area are controlled rationally and effectively, and the load-bearing capacity of the support system is improved. do.

The present application uses distributed optical fiber sensing technology to periodically and continuously monitor the strain and stress of the tunnel host rock that has been supported, and to monitor the changes in the fractured area in the tunnel due to the impact of mining and the force that changes the host rock. Accurately grasp the situation, provide reinforcement support for areas with large expansion of the crushing area, and depressurize areas with excessive stress, providing great security for tunnels where accidents occur frequently due to mining stress. offer.

The mining tunnel host rock monitoring and supporting method provided by the present application provides respective support according to the crushing condition of the deep tunnel host rock, whereby the small crushing areas are supported with low strength and the large crushing areas are supported with high strength. By continuously monitoring the strain and stress of the mother rock according to the set monitoring frequency, the area where the crushing expansion of the mother rock is large during the excavation or mining process is reinforced and supported, In addition, the area where the expansion of the crushed area is large is correspondingly reinforced and supported, and the area where the host rock stress is too large is depressurized, so as to avoid the later deformation of the tunnel, and the tunnel where the mining stress frequently causes accidents. provide security. Compared with the conventional empirically designed support means, the method of monitoring and supporting the host rock of the tunnel wall provided by the present application is more scientific and accurate, the effect of supporting the entire tunnel is enhanced, and the mining area is It reduces the support cost of deep tunnels, lowers the support repair rate, improves safety, and has good social and economic benefits.

1 is a flow schematic diagram of the present application; FIG. 1 is a technical logic diagram of the present application; FIG. 2 is a cross-sectional view of the dispersive optical fiber of the present application in a tunnel arrangement scheme; FIG. 4 is a distribution map of host rock strain with depth at one specific position of the tunnel of the present application. 1 is a schematic diagram of a change curve of host rock stress with depth of a rock formation of the present application; FIG. FIG. 4 is a schematic diagram of determining the timing of the secondary shoring of the present application; FIG. 4 is a top view of the size distribution of fractured areas in different sections of the gallery of the present application; It is the schematic of the host rock which performed the primary shoring and the secondary shoring of this application. 1 is a schematic diagram of a distributed optical fiber in the mining process of the present application; FIG.

FIG. 1 is a flow schematic diagram of a mining driveway host rock monitoring and supporting method provided by some embodiments of the present application. FIG. 2 is a detailed flowchart of a mining driveway host rock monitoring and supporting method provided by some embodiments of the present application. As shown in FIGS. 1 and 2, the method includes the following steps.

Step S10: continuously monitor the strain of the host rock according to the monitoring frequency of the distributed optical fiber to obtain the strain monitoring data of the host rock;

In the embodiments of the present application, the distributive optical fiber 29 is deployed during the excavation or mining process of the mine shaft, specifically as follows.

As shown in FIG. 3, according to the width, height and shape of the tunnel 1, the spacing and row spacing of the dispersed optical fibers 29 are set, and the dispersed optical fibers 29 are arranged according to the set spacing and row spacing. . The intervals and row intervals of the distributed optical fibers 29 are as follows.

1) If the distance along the radial direction of the tunnel 1 between adjacent distributed optical fibers 29 is 20-50 m, and the length of the section where the difference in geological production conditions is obvious in one tunnel 1 is greater than 20 m, At least one distributed optical fiber 29 has to be additionally arranged in the tunnel 1 in the section.

2) The number of dispersive optical fibers 29 arranged at the top of tunnel 1 is 3 or more, and the number of arrangements on both sides of the cross section and on the bottom plate is 2 or more.

In the embodiment of the present application, the number of distributed optical fibers 29 arranged on the cross-sectional top plate of the tunnel 1 is three, and the number of distributed optical fibers 29 arranged on both sides of the cross section and on the bottom plate is two. The interval between the radially adjacent distributed optical fibers 29 is 50 m.

The method of arranging the distributed optical fibers 29 is as follows. It is to perform grouting and hole sealing treatment on the hole.

The technical requirements for the design and construction of the tunnel are as follows.

1) The hole diameter of underground tunnel drilling should not be less than 50 mm, the radial direction of tunnel 1 should be 90°, and the inclination of the fixed focus should not exceed 1°.

2) After drilling, use underground compressed air to purge the drilled hole once, and clean the hole with fresh water.

3) After installing the distributed optical fiber 29, perform hole sealing and grouting in time, make the hole sealing length greater than 1 m, and hold the grouting pipe in the hole after grouting is completed.

When the dispersive optical fiber 29 is arranged, grouting is applied to the dispersive optical fiber 29, so that the dispersive optical fiber 29 and the mother rock are bonded together, and the distortion caused by the dispersed optical fiber 29 is converted into the distortion of the mother rock. Match, ie, the strain value of the dispersive optical fiber 29 equals the strain value of the host rock at the location.

When drilling a mine shaft, the distributed optical fiber 29 is placed at a position before 150 m away from the drilling work surface, and if during mining the distributed optical fiber 29 is not placed in a shaft subject to mining perturbations in the work surface, Distributed optical fibers 29 should be placed at a distance of 300 m in front of the mining work surface 14, and all distributed optical fibers 29 should be placed before the tunnel is subjected to mining stress, and the work surface If distributed optical fibers 29 are deployed during drilling in a shaft subject to mining perturbations, the shaft host rock 15 is continuously monitored using the distributed optical fibers 29 deployed during drilling.

When deploying the distributed optical fiber 29, the distributed optical fiber 29 should penetrate into the source rock stress area on the side of the tunnel, and the monitoring depth is generally greater than 5h, where h is the height of the tunnel. show. According to the monitoring results, if the dispersive optical fiber 29 does not enter the host rock plastic region 6 or the depth of penetration into the host rock elastic region 7 is less than 5 meters, the depth of the dispersed optical fiber 29 in this region should be increased. do.

In some optional embodiments, after the distributed optical fibers 29 are deployed, the monitoring frequency of the distributed optical fibers 29 needs to be established in order to periodically and continuously monitor the tunnel host rock 15 . Specifically, during a preset time period, the distributed optical fiber 29 continuously monitors the host rock distortion, determines the monitoring frequency of the distributed optical fiber 29, and the distributed optical fiber 29 operates according to the monitoring frequency. to periodically and continuously monitor the host rock strain to obtain the host rock strain monitoring data.

In the embodiment of the present application, the monitoring frequency of the distributed optical fiber 29 refers to the monitoring period of the distributed optical fiber 29, that is, the time interval for collecting two host rock distortion data, and the monitoring frequency of the distributed optical fiber 29 is , is determined according to the magnitude of the host rock strain value. More specifically, after the distributed optical fiber 29 is installed, the dispersed optical fiber 29 continuously monitors the host rock strain value during a preset time period. , the host rock strain value is large and the host rock movement is active, the monitoring frequency of the distributed optical fiber 29 is increased, and the host rock strain is periodically and continuously monitored according to the set monitoring frequency. do.

In a specific example, considering the time course of host rock strain, the monitoring frequency of the dispersed optical fiber 29 is determined based on the host rock strain value monitored by the dispersed optical fiber 29 within a day. When the host rock strain value is greater than 500 με, the monitoring frequency of the dispersed optical fiber 29 is once/d (once a day), and when the host rock strain value within a day is 100 με-500 με, The monitoring frequency is 1/2d (once every 2 days), and when the host rock distortion value within a day is less than 100 με, the monitoring frequency of the distributed optical fiber 29 is (1-2) times/14d (14 monitoring once or twice per day), as shown in the table below.

According to the set monitoring frequency, the host rock crushing condition is continuously monitored at different positions in the tunnel.

In the embodiment of the present application, the distributed optical fiber 29 adopts a sensing distributed optical fiber 29 with Brillouin effect, which can reflect the change of environmental temperature and its own strain, Since the temperature of the rock 15 tends to be constant, we ignore temperature effects and, as a default, the amount of change in Brillouin frequency shift is caused by the strain of the dispersive optical fiber 29 .

Based on distributed optical fiber 29 sensing technology, depending on the relationship between Brillouin frequency shift and distortion,

上記式で母岩歪み監視データを算出する。

The host rock strain monitoring data is calculated using the above formula.

は比例係数を示し、値が約４９３ＭＨｚを取り、εは光ファイバー／母岩の歪み値を示し、即ち、母岩歪み監視データである。 In the formula, vB(ε) indicates the frequency shift amount of the Brillouin frequency when the strain is ε, vB(0) indicates the frequency shift amount of the Brillouin frequency when the strain is 0,

denotes a proportionality coefficient and takes a value of about 493 MHz, and ε denotes an optical fiber/host rock strain value, ie, host rock strain monitoring data.

Embodiments of the present application employ distributed optical fiber sensing technology to continuously monitor the strain at different locations in the tunnel and at different depths in the host rock according to the relationship between the Brillouin frequency shift and the strain of the distributed optical fiber. Thereby, data is obtained more accurately and easily, and fiber optic sensing can operate normally under harsh or extreme conditions and is less affected by the mine shaft environment.

Step S20, according to the host rock strain data obtained by interpolating the host rock strain monitoring data, the tunnel is divided into regions, and the load-bearing regions at different positions of the tunnel and the crushing regions at different sections of the tunnel. get the size of

After the distributed optical fiber 29 acquires the host rock strain monitoring data, the host rock strain monitoring data is processed based on the interpolation method to acquire the host rock strain data.

In one specific example, the host rock strain monitoring data is processed based on an interpolation method, specifically MATLAB programming: vq=griddata(x, y, z, v, xq, yq, zq, method) to interpolate the host rock strain monitoring data to obtain the host rock strain data. It can be understood that one of 'Linear', 'Nearest', 'Natural', 'Cubic' or 'V4' can be selected as the interpolation method.

In some optional embodiments, interpolating the host rock strain monitoring data specifically interpolates the host rock strain monitoring data along the radial direction and the running direction of the tunnel, respectively, and correspondingly: It is to acquire the wall rock strain data along the radial direction and the running direction of the tunnel.

Based on the host rock strain data along the radial direction of the tunnel, the size of the fracture area in different sections of the tunnel and the load-bearing areas at different locations of the tunnel are correspondingly determined.

In a specific example, images are visualized for the host rock distortion data along the running direction of the tunnel and the radial direction of the tunnel. Get the size of a region intuitively.

Furthermore, according to the size of the crushing area in different sections of the tunnel, the tunnel along the running direction is divided into three sections: a small crushing area section 23, a medium crushing area section 24, and a large crushing area section 25. As shown in , as the division standard, when LP ≤ 40 cm, it is a small crushing region section 23, when 40 cm < LP ≤ 150 cm, it is a medium crushing region section 24, and when LP > 150 cm, large crushing Let area division 25, where LP is the size of the fractured area, ie the thickness of the loosened area of the tunnel host rock 15;

Based on the load-bearing areas at different positions of the gallery, the gallery rock 15 along the radial direction is divided into a fracture zone, a plastic zone 6 and an elastic zone 7, as shown in FIG. It should be noted that in the present embodiment, the fracture area is the loosened area of the tunnel host rock 15, which is determined according to the strain value measured by the distributed optical fiber 29, and the fractured rock near the tunnel. The body has the thickness of the loose area, and has the characteristics of expansion and deformation, and the fractured rock body within the loose area bears the load through the hinge connection, and the load-bearing capacity is very small. . As a result of continuous monitoring by the distributed optical fiber 29, there is variation in the amount of strain change in the host rock from the surface to the deep part of the tunnel. Region 6, mainly the load-bearing region, exhibits compressive deformation.

In some optional embodiments, after determining the size of the load-bearing area at different locations in the gallery and the fracture area in different sections of the gallery, the length and location of the fracture area in the different sections of the gallery are further determined. and the distance from the outer boundary 26 of the fracture zone and the outer boundary of the plastic zone 6 to the tunnel, and graphically and intuitively displaying the marked results in a visualization manner. including

The host rock distortion data obtained by monitoring by the distributed optical fiber 29 is interpolated, and based on the interpolated host rock distortion data, the tunnel is divided into areas, and the load bearing areas at different positions of the tunnel. and obtain the sizes of fractured areas in different sections of the gallery. Compared to conventional data processing methods, this method is simpler and more accurate, and the visualized images can be used to intuitively and quickly observe the state of rock fragmentation in each area of the tunnel. .

Step S30, according to the relationship between host rock stress and strain, according to the host rock strain data, the load-bearing areas at different positions of the tunnel and the size of fractured areas at different sections of the tunnel; Determine the timing and method of primary support, secondary support and reinforcement.

In the mining tunnel excavation process, it is necessary to perform leading support treatment on the host rock in order to prevent accidents such as collapse and collapse due to crushing of the host rock. For areas with severe geological conditions and loose soil, the joint support method of the leading small conduit and the leading conduit shelf is used to stabilize the host rock. improve sexuality.

In some optional embodiments, host rock distortion data obtained from continuous monitoring of distributed optical fiber 29 is used to determine the timing and treatment of primary shoring.

After the excavation of the tunnel, the host rock stress is redistributed, and along with the movement of the face face in the tunnel, the deformation speed of the host rock increases from the host rock to the face face. deforms without extending into the tunnel, indicating that the deformation of the fractured region reaches a stable stage. Based on the host rock distortion data obtained by continuous monitoring by the distributed optical fiber 29, it is determined whether the deformation of the host rock tends to stabilize. When the host rock strain data obtained by continuous monitoring is 200 με/d, it is considered that the deformation of the host rock tends to reach a stable state. In the embodiments of the present application, the timing at which the deformation of the host rock tends to reach a stable state is the optimum timing for the primary support.

Since the strength of the host rock crushing area is weak, caving of the top plate is likely to occur due to the crushing of the host rock. As shown in FIG. 8, anchor rods 22 are used to support the host rock fracture area to construct an artificial pressure-resistant arch in the host rock fracture area. The interaction of the host rock and the anchor rod builds an artificial pressure-resistant arch in the fractured zone of the host rock to improve the stability and load-bearing capacity of the host rock in the fractured zone layer.

The specific parameters of the anchor rods 22 used in primary support are as follows.

a) The length of the anchor rod 22 is:

In the formula, L is the length (m) of the anchor rod 22, LP is the thickness (m) of the loosened region of the tunnel host rock, and L1 is the stable host rock other than the region where the anchor rod 22 is loosened. L2 is the exposed length (m) of the anchor rod 22 in the tunnel.

b) When the spacing and line spacing of the anchor rods 22 are made equal, the anchoring force of the anchor rods 22 and the spacing and line spacing are as follows.

In the formula, D is the spacing and row spacing (m) of the anchor rods 22, Qmin is the minimum anchoring force (kN) of the anchor rods 22, and γ is the gravitational density of the host rock (kN/m3).

c) The diameter of the anchor rod 22 is:

In the formula, d is the diameter (mm) of the anchor rod 22, Q is the anchoring force (kN) of the anchor rod 22, and σt is the tensile strength of the anchor rod 22.

In some optional embodiments, prior to determining the timing of secondary support, first determine the corresponding host rock stress-strain curve based on the lithology of the tunnel host rock 15, type, rock It can be understood that host rocks of different quality correspond to different stress values under the same strain conditions, and the host rock stress-strain curves are also different.

母岩応力を算出する。 Based on host rock strain data, depending on the relationship between host rock stress and strain,

Calculate the host rock stress.

where σ is the host rock stress value (N/m2), ε is the host rock strain value, E is the elastic modulus (Pa), and E is the type of rock formation at different host rock depths. determined accordingly.

In some optional embodiments, after calculating the host rock stress, the host rock stress is further visualized and a change curve of the host rock stress with the depth of the rock formation (i.e., the host rock stress with the depth of the rock formation). As shown in FIG. 5, the change curve of the host rock stress with the depth of the rock layer obtained shows that the host rock stress is greater than the host rock source rock stress of 1.5 times is defined as the host rock critical load bearing region 8, thereby determining the location and thickness of the host rock critical load bearing region 8. It should be noted that the critical load-bearing area 8 is the area of shear stress concentration in the tunnel, and bears most of the mine pressure, and has a critical load-bearing effect on the long-term stability of the host rock. , which is related to the balance of the overall load-bearing structure, in that when shear failure occurs, the predominant wall rock load-bearing region shifts inward.

FIG. 6 is a schematic diagram of determining the timing of secondary shoring provided by some embodiments of the present application. As shown in FIG. 6, according to the host rock stress, the timing of the secondary support is determined based on the host rock stress-strain curve. Specifically, based on the host rock stress-strain curve, the first point The section between (B point) and the second point (C point) is the plastic deformation stage of the host rock, and the strain of the host rock is between the first strain threshold and the second strain threshold to determine the timing of the secondary support during the tunnel excavation process.

Here, the first strain threshold is half the difference between the strain value corresponding to the first point (B point) and the strain value corresponding to the second point (C point) in the plastic deformation stage of the host rock. be.

The second strain threshold is three quarters of the difference between the strain value corresponding to the first point (B point) and the strain value corresponding to the second point (C point) at the stage of plastic deformation of the host rock.

The first point is the point when the host rock begins to undergo plastic deformation and the second point is the point corresponding to when the host rock reaches its ultimate yield strength.

In the tunnel excavation process, by setting the time when the strain of the host rock is between the first strain threshold and the second strain threshold as the optimal support timing for the secondary support, the host rock stress in the plastic region 6 is relaxed and , the host rock in the plastic zone 6 still has a certain self-supporting capacity, and the joint action of the self-supporting capacity of the host rock in the plastic zone 6 and the secondary support enhances the supporting effect.

Depending on the timing of secondary support, the size of the crushed area in different sections of the tunnel, and the eight areas of the host rock critical load bearing area, different secondary support treatments can be applied to the host rock in different areas. Specifically, it is as follows.

1) When the optimal support timing is reached, first determine the lithology of the host rock in the plastic region. To prevent the stress from being too large and the stored energy from impacting the ground pressure.

A specific decompression treatment method is as follows. Based on the host rock strain monitoring data obtained by injecting high-pressure water into the hole and hydraulically fracturing the host rock around the host rock critical load bearing area 8, and continuously monitoring the host rock distortion by the distributed optical fiber 29. Then, when a crushing crack occurs in the outer peripheral host rock of the host rock important load bearing area 8, water injection is stopped.

2) Next, according to the range of the host rock important load bearing region 8, grout injection reinforcement treatment is performed on the important load bearing region 8, and shearing of the plastic zone host rock in the important load bearing region 9 after grouting is performed. Improve resistance ability.

3) The tunnel wall elastic region 7 has high strength, most of the stress in the wall rock is borne, and the depth of the elastic region 7 is large, so that the general anchor rod 22 is difficult to perform the supporting function, so that A support method of "suspension by anchor cable 10" is adopted.

4) Anchor cables 10 cover and support the moderate crushing zone 24 and the large crushing zone 25, and the stability of the host rock in the elastic zone 7 is used to support the load bearing foundation of the entire support layer. and increase the load-bearing capacity of the entire tunnel.

Specific parameters of the anchor cable 10 can be determined by the following method.

式中において、Ｌ５はアンカーケーブル１０の長さ（ｍ）であり、ＬＳは坑道から弾性領域７の境界までの垂直距離（ｍ）であり、

はアンカーケーブル１０が弾性領域７の内部にアンカーした深さ（ｍ）であり、Ｌ２は坑道でのアンカーロッド２２の露出長さ（ｍ）であり、
アンカーケーブル１０の間隔・行間隔：

式中において、Ｓａはアンカーケーブル１０の間隔・行間隔（ｍ）であり、［σａ］は単一のアンカーケーブル１０の限界破断力（ｋＮ）であり、γは母岩の重力密度（ｋＮ／ｍ３）である。 Anchor cable 10 length:

where L5 is the length (m) of the anchor cable 10, LS is the vertical distance (m) from the tunnel to the boundary of the elastic region 7,

is the depth (m) to which the anchor cable 10 is anchored inside the elastic region 7, L2 is the exposed length (m) of the anchor rod 22 in the tunnel,
Anchor cable 10 spacing/line spacing:

In the formula, Sa is the spacing and row spacing (m) of the anchor cables 10, [σa] is the critical breaking force (kN) of a single anchor cable 10, and γ is the gravitational density of the host rock (kN/ m3).

5) As shown in FIG. 8, a steel arch frame support is provided in the large crushing zone section 25, and the medium crushing zone section 24 and the large crushing zone section 25 are subjected to concrete 11 injection treatment, and the concrete is made into steel. By forming the concrete housing 12 by covering the arch frame made of steel and forming the anchor system of the anchor rod 22 and the anchor cable 10 in the moderate crushing area section 24, the surface layer of the large crushing area section 25 forms a single arch frame and Form a concrete injection column housing, build a joint shoring system of anchor rod cables and concrete housing 12 in medium crushing area section 24, and a joint shoring system of anchor rod cables and steel arch frame concrete housing 12 in large crushing area section 25. do.

Based on the host rock distortion data obtained by continuous monitoring of the distributed optical fiber 29, the specific timing of the optimal support for the primary support and the secondary support is determined, and the support is provided according to the determined support timing. to rationally and effectively control the deformation state of the crushing area and the stress relaxation state of the plastic area, and improve the load-bearing capacity of the support system.

In the examples of the present application, after the secondary shoring, the host rock tends to reach a stable state quickly due to the combined action of the initial shoring, the primary shoring, and the secondary shoring. The layer provides the safety stock for the gallery, and the lining layer counteracts the impact of subsequent loads, such as drilling perturbations or burst loads, on the gallery. The lining process is completed by conventional lining methods, specifically: cleaning the primary supporting surface--covering the waterproof plate geotextile--tying the rebars--fixing the secondary lining trolley--concrete pouring--demolding--curing.

FIG. 9 is a schematic diagram of the distributed optical fiber 29 in the mining process provided by some embodiments of the present application, as shown in FIG. .

In the mining process, based on the host rock distortion data obtained by continuously monitoring the tunnel host rock 15 by the distributed optical fiber 29, the slow crushing state of the host rock due to the mining perturbation or the host rock in the excavation site area 4 can be determined. 2 grasps the expansion condition of each load-bearing area after the burst crushing of the tunnel host rock 15 in the vicinity becomes severe when a movement such as a collapse or collapse occurs.

In the tunnel mining process, in response to the host rock strain data being in the critical interval, the host rock in the plastic region is decompressed, where the critical interval is determined according to the host rock stress-strain curve, specifically In the mining process, the host rock is severely crushed by mining perturbation or the activity of the host rock in the mining site area 4 . Judging whether the host rock stress is in the critical interval, and if the host rock stress is in the critical interval and the elasticity and brittleness of the host rock in the plastic region are high, the host rock in the plastic region of the tunnel is subjected to decompression treatment. , the depressurizing method and the tunnel excavation process, the depressurizing method for secondary support is the same. Here, the critical interval is determined based on the host rock strain data according to the host rock stress-strain curve. It is an interval of 3/4 from .

In some optional embodiments, during the mining process, the reinforcement process further comprises reinforcing the host rock of the fractured area according to the size of the fractured area in different sections of the gallery, specifically is affected by mining perturbations in the mining process, the thickness of the loose region of the tunnel host rock 15 increases, the small crushing region slowly expands as a medium crushing region, and the medium crushing region becomes a large crushing region. is extended as Distributed optical fiber 29 continuously monitors the tunnel host rock 15, obtains the host rock distortion data, and performs interpolation and visualization processing to determine the extension of the load-bearing area at different positions of the tunnel during the mining process.

According to the thickness of the loosened region of the tunnel host rock 15 (the size of the expanded crushed region) in the tunnel mining process, specifically, the small crushed region is expanded as a medium crushed region as a reinforcing support method. When expanded from LP ≤ 40 cm to 40 cm < LP ≤ 150 cm, the anchor cable 10 is used for reinforcement support, and when the moderately crushed region is expanded as a large crushed region, that is, 40 cm < LP ≤ 150 cm When extended from LP>150 cm, the steel arch frame is used for reinforcement support, the steel arch frame concrete housing 12 is constructed, and when the extension of the crushing area of the major crushing area section 25 exceeds 100 cm, the area is reinforced with long anchor cables 10, where LP is the thickness of the loosened area of the tunnel wall 15 during the tunnel mining process. The parameters of the anchor cables 10 for reinforcement support and the method of determining the parameters of the anchor cables 10 used for secondary support in the tunnel excavation process are the same.

In the mining process, decompression treatment and reinforcement support can effectively avoid the late deformation of the tunnel, reduce the occurrence of accidents, and increase the stability of the tunnel.

Leading support, secondary support and reinforcement treatments complete the tunnel support process. At this time, the distributed optical fiber 29 continuously monitors the tunnel host rock 15 according to the set monitoring frequency. Due to the concentration of stress and the aging of the loosened area, the small loosened area will become a moderately large loosened area over time, and if not timely and effectively supported, the tunnel host rock 15 will be damaged. It deforms easily and becomes unstable. Therefore, after completing the tunnel support, the distributed optical fiber 29 will still continuously monitor according to the determined monitoring frequency to ensure the stability and safety of the tunnel.

1 Tunnel 2 Primary support system 3 Secondary support system 4 Excavation area 5 Crushing area 6 Plastic area 7 Elastic area 8 Important load bearing area 9 Important load bearing area after grouting 10 Anchor cable 11 Concrete layer 12 Steel arch frame Concrete housing 14 Mining work surface 15 Tunnel host rock 22 Anchor rods 23 Small fracture area section 24 Medium fracture area section 25 Large fracture area section 26 Fracture area outer boundary 29 Distributed optical fiber

Claims (8)

A method of monitoring and supporting a mining tunnel host rock, comprising:
step S10 of continuously monitoring the strain of host rock according to the monitoring frequency of the distributed optical fiber to obtain host rock strain monitoring data; The optical fiber continuously monitors the strain of the host rock, determines the monitoring frequency of the distributed optical fiber, and the distributed optical fiber periodically and continuously adjusts the strain of the host rock according to the monitoring frequency. a step S10 of monitoring and obtaining said host rock strain monitoring data;
Based on the host rock distortion data obtained by interpolating the host rock distortion monitoring data, the tunnel is divided into areas, and the load bearing areas at different positions in the tunnel and the size of the crushing area in different sections of the tunnel. Specifically, the host rock distortion monitoring data is interpolated along the radial direction and the running direction of the tunnel, and correspondingly, the strain along the radial direction and the running direction of the tunnel Obtaining host rock strain data and correspondingly load-bearing regions at different locations of the gallery and fracture regions at different sections of the gallery based on the host rock strain data along the radial direction and the running direction of the gallery. determining 20 the magnitude of and
primary support of the host rock based on the host rock strain data, the size of the load-bearing areas at different locations of the gallery and the fracture zones at different sections of the gallery, depending on the relationship between host rock stress and strain; A method for monitoring and supporting a mining tunnel host rock, characterized in that it includes a step S30 of determining the timing and treatment method of secondary support and reinforcement treatment. According to the size of the fractured areas in different sections of the tunnel, the tunnel host rock is divided along the running direction into small fractured area sections, medium fractured area sections and large fractured area sections,
The small fracture area section is LP≦40 cm, the medium fracture area section is 40 cm<LP≦150 cm, and the large fracture area section is LP>150 cm, where LP is the tunnel bedrock. is the thickness of the loose region of
Mining tunnel host rock according to claim 1, characterized in that the tunnel host rock is divided into a fracture zone, a plastic zone and an elastic zone according to the load-bearing areas at different positions of the tunnel. Surveillance and support methods. In step S30, determining a corresponding host rock stress-strain curve based on the lithology of the tunnel host rock;
Based on the host rock strain data, host rock stress is calculated according to the relationship between host rock stress and strain,
3. A method of monitoring and supporting a mining tunnel host rock according to claim 2, characterized by determining the timing of the secondary support based on the host rock stress-strain curve in response to the host rock stress. Determining the timing of the secondary support based on the host rock stress-strain curve in response to the host rock stress specifically includes:
determining the timing of the secondary support during tunnel excavation in response to the host rock strain data being between a first strain threshold and a second strain threshold during the stage of plastic deformation of the host rock;
wherein the first strain threshold is half the difference between the strain value corresponding to the first point and the strain value corresponding to the second point in the stage of plastic deformation of the host rock;
the second strain threshold is three quarters of the difference between the strain value corresponding to the first point and the strain value corresponding to the second point in the stage of plastic deformation of the host rock;
4. The method according to claim 3, characterized in that the first point is the point when the host rock starts to undergo plastic deformation and the second point is the point corresponding to when the host rock reaches the precipitation limit. Methods for monitoring and supporting mining tunnel host rocks. After determining the timing of the secondary support based on the host rock stress-strain curve in response to the host rock stress,
providing different secondary support treatments to the host rock in different regions based on the timing of the secondary support, the size of the fractured regions in different sections of the gallery, and critical load bearing regions of the host rock; A host rock critical load-bearing region is a corresponding region in the tunnel host rock that has a host rock stress greater than 1.5 times the host rock source rock stress, and the host rock stress is related to the relationship between host rock stress and strain. 5. A method for monitoring and supporting a mining tunnel host rock according to claim 4, wherein said host rock strain data is accordingly calculated based on said host rock strain data. Specifically, performing different secondary shoring treatments on the host rock in the different regions includes:
depressurizing the plastic region according to the lithology of the host rock in the plastic region;
and/or
grout injection reinforcement treatment is performed on the host rock important load bearing area,
and/or
Suspension support is provided with anchor cables for the elastic region of the tunnel host rock,
and/or
For the medium crushing area section and the large crushing area section, anchor cables support the covered plastic area,
and/or
Supporting the large crushing zone with a steel arch frame, performing concrete injection treatment on the medium crushing zone and the large crushing zone, and coating the steel arch frame with the concrete. A method for monitoring and supporting a mining tunnel host rock according to claim 5, characterized in that: In step S30, as the timing and processing method of the reinforcing process, specifically,
depressurizing the host rock in the plastic region in response to the host rock strain data being in the critical interval during the tunnel mining process, wherein the critical interval is determined based on the host rock stress-strain curve;
and/or
Monitoring and supporting the mining tunnel host rock according to claim 1, characterized in that during the tunnel mining process, the fractured areas in the tunnel are reinforced and supported according to the size of the fractured areas in different sections of the tunnel. Method. In step S30, the timing of the primary support is to provide the primary support to the tunnel host rock in response to the fact that the host rock strain is 200 με/d or less during the tunnel excavation process. Item 2. A method of monitoring and supporting mining tunnel host rock according to item 1.

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