A drilling retrievable microseismic sensor installation method

Abstract

The present invention discloses a drilling recyclable microseismic sensor installation method, comprising the following steps: S1: making a sensor installation base and a hole protection steel pipe; S2: drilling a hole in the rock mass of the monitoring area; S3: assembling the microseismic sensor, the installation base, and the hole protection steel pipe and placing them in the borehole; S4: sealing the borehole and grouting; S5: connecting a collector and performing microseismic monitoring; S6: recovering the microseismic sensor. The present invention aims at the problems of high ground stress, soft and broken rock mass, and large mining impact in underground engineering, realizes the protection, recovery and recycling of microseismic sensors, and improves the coupling effect of drilling installation of microseismic sensors and the quality of signal acquisition.

Description

Technical Field

[0001] The invention relates to the technical field of microseismic monitoring, and in particular to a method for installing a drilled retrievable microseismic sensor. Background Art

[0002] Microseismic monitoring technology has been widely used in rock stability monitoring and rock dynamic disaster monitoring and early warning of underground projects such as mines and tunnels. Among them, microseismic sensors are an important part of the microseismic monitoring system, and their installation coupling quality is one of the key factors affecting the accuracy and reliability of microseismic monitoring. In practical applications, microseismic sensors are often installed in two ways: permanent (non-recoverable) and temporary (recoverable). Since the underground engineering mining area, that is, the key monitoring area, is in a process of change all year round, and the cost of microseismic sensors is high, recyclable installation is more practical. Recyclable installation can be divided into an exposed installation method in which the sensor is installed on the anchor rod, the bottom plate base of the tunnel, and the installation method in which the sensor is installed in the hole in the rock mass drilled hole. Among them, the exposed installation method is simple and convenient to install, but because the sensor is directly exposed in underground spaces such as tunnels and tunnels, the anti-interference ability is poor. At present, there are many technical solutions for installing sensors in holes, but there are some practical problems. For example, some are directly installed in bare holes. However, for areas with large in-situ stress and mining influence and soft and broken rock formations in deep underground projects, the boreholes often collapse, deform, and are damaged, and it is difficult to recover the sensors after installation. In addition, it is difficult to make the bottom of the borehole completely flat on site, and it is difficult to effectively couple the sensor with the bottom of the borehole. Although some technical solutions, such as Chinese patent CN 110007339B, use casing to protect the hole, only using casing in deep high-in-situ stress or soft and broken rock mass often does not have a long-term effective hole protection effect. Although this technology also uses yellow mud as a coupling agent to increase the coupling of the sensor, on the one hand, materials such as yellow mud are easy to shrink and produce cracks when dried, affecting the monitoring effect. In addition, the bottom of the hole will also deform and crack after long-term monitoring, further affecting the signal monitoring quality. Some installation devices and methods, such as Chinese patent CN 102053257B and Chinese patent application CN 105445784 A. The structure and installation process of this type of invention device are relatively complex, and the requirements for the flatness of the bottom of the hole are extremely high, and the on-site construction is very difficult. In addition, Chinese patent application CN117075189 A discloses a microseismic sensor cyclic installation device, installation and recovery method. The invention installs the anchor rod at the bottom of the borehole, and the sensor is installed on the anchor rod in the borehole. Its essence is to connect the sensor to the rock mass through the anchor rod. The microseismic wave signal is transmitted to the sensor through the anchor rod, and the quality of the microseismic signal will be greatly affected; in addition, since the anchor rod must be installed at the bottom of the borehole, the borehole length is greatly limited. Therefore, the patent specially designs a noise reduction isolation layer to compensate for the effective shielding of the shallow borehole against environmental noise; in addition, the patent does not reinforce the borehole, especially the bottom of the hole is not reinforced, and due to the limitation of anchor rod installation, the borehole is very shallow. In underground engineering, the shallow rock mass is often in a broken state, especially for long-term monitoring, it is more prone to deformation and damage. Once the bottom of the hole is deformed and damaged, it will be difficult to monitor the microseismic signal, and the borehole cannot reach the ideal state. If there are stones in the borehole, it cannot be installed on the anchor rod.Moreover, the above three patents focus on the fixed installation of the sensor at the bottom of the hole, and do not consider the support of the entire length of the borehole. Once deformation, hole collapse, etc. occur, it cannot be recovered. They are not suitable for long-term monitoring of deep mines with high ground stress and soft rock conditions. Summary of the invention

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a method for installing a recoverable microseismic sensor in a borehole, which solves the problems of damage to the microseismic sensor, inability to recover, poor coupling effect of the borehole installation, low signal acquisition quality, etc. caused by factors such as ground stress and mining stress, soft and broken rock formations during the drilling installation and monitoring of the microseismic sensor. The method provides full protection for the microseismic sensor in the borehole, improves the service time of the microseismic sensor, enhances the coupling effect of the microseismic sensor, and realizes the recovery and recycling of the microseismic sensor.

[0004] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0005] A drilling retrievable microseismic sensor installation method comprises the following steps:

[0006] S1: Make the sensor installation base and the hole-protecting steel pipe;

[0007] S2: drilling holes on the rock mass in the monitoring area;

[0008] S3: Assemble the microseismic sensor, mounting base, and hole-protecting steel pipe and place them in the drilled hole;

[0009] S4: Drilling and plugging and grouting;

[0010] S5: Connect the data collector and conduct microseismic monitoring;

[0011] S6: Recover the microseismic sensor.

[0012] Preferably, step S1 is as follows: select a a , length l d , the inside of the steel pipe with a wall thickness of e is filled with cement as the sensor mounting base, and a bolt is cast at the center of the front end of the sensor mounting base. The front end of the steel pipe of the sensor mounting base is provided with an external thread; select n roots with an outer diameter of d a , length l h , a steel pipe with a wall thickness of e is used as a hole-protecting steel pipe. An internal thread is set at one end of the hole-protecting steel pipe, and an external thread is set at the other end. The length of the external thread set on the steel pipe of the sensor installation base is The length of the internal and external threads of the hole-protecting steel pipe is The bolt length is l1 and the outer diameter is d1.

[0013] Preferably, step S2 is specifically as follows: constructing a borehole with a length of L and a diameter of D on the rock mass in the monitoring area.

[0014] Preferably, step S3 is as follows: a bolt hole is provided at the bottom of the microseismic sensor, a hexagonal nut is provided at the front end, a signal cable is provided at the front end of the hexagonal nut, the microseismic sensor is connected to the bolt of the mounting base through the bolt hole, n hole-protecting steel pipes are threadedly connected in sequence, the front end of the mounting base where the microseismic sensor is installed is threadedly connected to the end of the leftmost hole-protecting steel pipe with an internal thread, the microseismic sensor, the mounting base, and the n hole-protecting steel pipes are pushed into the borehole as a whole, and the rightmost hole-protecting steel pipe protrudes outward from the borehole by a length of l; the length of the microseismic sensor is l s The inner diameter of the bolt hole is d1 and the depth is l1; the length of the hexagonal nut is l s1 , nominal diameter is d s1 .

[0015] Preferably, step S4 is specifically as follows: the borehole opening is sealed with a curing agent, and then the hole protection steel pipe and the borehole annulus are grout-reinforced by split grouting.

[0016] Preferably, step S5 is specifically as follows: after the grouting liquid is completely solidified, the microseismic sensor is connected to the collector via a signal cable, and the microseismic monitoring is tested and performed.

[0017] Preferably, step S6 is specifically as follows: after the microseismic monitoring is completed, a sensor recovery rod is used to extend into the hole-protecting steel pipe, and the microseismic sensor is rotated to remove, thereby completing the microseismic sensor recovery work.

[0018] Preferably, the calculation formula of the grouting liquid volume V in step S4 is as follows:

[0019]

[0020] V = 1.5V*.

[0021] Preferably, the sensor recovery rod in step S6 includes: a hollow pushing rod, a sensor carrying container matching with the microseismic sensor is provided at the front end of the pushing rod, a hexagonal nut container matching with the hexagonal nut is provided at the end of the sensor carrying container close to the pushing rod, and an extension rod is provided at the end of the pushing rod away from the microseismic sensor and is threadedly connected with the hexagonal nut; the sensor recovery rod is used to extend into the hole-protecting steel pipe, the signal cable passes through the hollow pushing rod and the extension rod, the sensor carrying container and the hexagonal nut container are respectively mounted on the microseismic sensor and the hexagonal nut, and the microseismic sensor can be separated from the sensor mounting base by rotating the extension rod.

[0022] Preferably, before the microseismic sensor is bolted to the mounting base in step S3, a coupling agent is applied to the bottom of the microseismic sensor.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The hole protection steel pipe is made of high-strength steel pipe. With the splitting grouting method, the hole protection steel pipe and the surrounding area of ​​the borehole are filled with cement grouting liquid. The solidified cement grouting liquid plays a supporting role, further strengthening the protection of the sensor. Under the conditions of high ground stress and soft and broken rock mass, the sensor installation borehole can be effectively protected to deal with the problems of hole collapse, rockfall, deformation, etc., and ensure the smooth recovery work.

[0025] 2. Split grouting uses high-pressure grouting technology to reinforce soft and broken rock formations. Ordinary Portland cement materials with fast coagulation and hardening and high hardness are used to inject into the borehole. During the grouting process, the slurry at the outlet of the grouting pipe applies additional compressive stress to the surrounding rock mass. The slurry splits along the cracks in the borehole from the low-strength areas of the rock mass to the high-strength areas. The slurry split into the rock mass forms a network or skeleton for reinforcing the rock mass. Split grouting can use its hydraulic pressure to produce split pores in the formation, improve the injectability of the formation, and thus meet the requirements of grouting reinforcement. This method fills the rock cracks around the borehole and reinforces it. It can not only effectively protect the steel pipes and sensors in the borehole, but also reduce the interference of broken rocks on the microseismic signal during propagation, prevent the distortion of the microseismic signal during propagation, improve the accuracy of the microseismic signal when it reaches the sensor, and realize long-term and high-quality monitoring of the microseismic sensor in the borehole.

[0026] 3. The sensor installation base is installed on a flat surface. After the sensor is installed with a special coupling agent, the coupling agent between the sensor and the installation base can fill the tiny gap, increase the fit between the sensor and the installation base, and ensure the coupling effect of the sensor. With the splitting grouting process, the rock mass, the installation base and the microseismic sensor form a whole, and the deep hole installation sensor plays a role in shielding noise, which can improve the accuracy of sensor signal acquisition.

[0027] 4. During the installation of the microseismic sensor, leave a distance between the installation base and the bottom of the drill hole, and fill it with grouting liquid to avoid poor contact between the installation base and the bottom of the hole due to the uneven bottom of the hole; the hole protection steel pipe extending from the hole mouth can prevent the hole mouth from collapsing and the rock from breaking and falling to bury the drill hole.

[0028] 5. The hole-protecting steel pipe can be freely connected and lengthened, and the sensor can be flexibly installed in shallow, medium, long, and extra-long boreholes in a recyclable manner, effectively solving the problem that it is difficult for sensors to form an optimized monitoring network in the confined space of underground projects.

[0029] 6. The microseismic sensor, mounting base, and hole-protecting steel pipe assembly of the present invention can be installed in advance outside the drilled hole, avoiding the problem of blindly installing the microseismic sensor in the drilled hole. The installation coupling quality is high, the operation is simple, and the difficulty of on-site operation is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 The figure is a flow chart of the method of the present invention.

[0032] Figure 2 This is a schematic diagram of the assembly of the microseismic sensor, mounting base, and hole-protecting steel pipe.

[0033] Figure 3 It is a schematic diagram of the cross section of the push rod.

[0034] Figure 4 Schematic diagram of the sensor cross section.

[0035] In the figure: 1. rock mass; 2. drilling hole; 3. grouting liquid; 4. sensor mounting base; 5. hole-protecting steel pipe; 51. internal thread; 52. external thread; 6. coupling agent; 7. microseismic sensor; 71. bolt hole; 8. hexagonal nut; 9. signal cable; 10. curing agent; 11. bolt; 12. sensor carrying container; 13. hexagonal nut container; 14. push rod; 15. extension rod. DETAILED DESCRIPTION

[0036] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0037] like Figure 1-4 As shown, a drilling retrievable microseismic sensor installation method comprises the following steps:

[0038] S1: Make the sensor installation base 4 and the hole-protecting steel pipe 5;

[0039] A steel pipe with an outer diameter of 50mm, a length of 100mm and a wall thickness of 2mm is selected and filled with cement as the sensor mounting base 4, and a bolt 11 is cast at the center of the front end of the sensor mounting base 4, and an external thread is set at the front end of the steel pipe of the sensor mounting base 4; 10 steel pipes with an outer diameter of 50mm, a length of 2000mm and a wall thickness of 2mm are selected as the hole-protecting steel pipes 5, one end of the hole-protecting steel pipe 5 is provided with an internal thread 51, and the other end is provided with an external thread 52; the length of the external thread set on the steel pipe of the sensor mounting base 4 is 50mm; the length of the internal thread 51 set at one end of the hole-protecting steel pipe 5 is 50mm, and the length of the external thread 52 at the other end is 50mm; the length of the bolt 11 is 15mm and the outer diameter is 7mm.

[0040] S2: drilling holes on rock mass 1 in the monitoring area;

[0041] A borehole 2 with a length of 19.5 m and a diameter of 96 mm was constructed on the rock mass 1 in the monitoring area.

[0042] S3: Assemble the microseismic sensor 7, the mounting base 4, and the hole-protecting steel pipe 5 and place them in the drilled hole;

[0043] A bolt hole 71 is provided at the bottom of the microseismic sensor 7, and a hexagonal nut 8 is provided at the front end. A signal cable 9 is provided at the front end of the hexagonal nut 8. The microseismic sensor 7 is connected to the bolt 11 of the mounting base 4 through the bolt hole 71, and 10 hole-protecting steel pipes 5 are threadedly connected in sequence. Before the microseismic sensor 7 is connected to the bolt 11 of the mounting base 4, a coupling agent 6 is applied to the bottom of the microseismic sensor 7; the front end of the mounting base 4 on which the microseismic sensor 7 is installed is threadedly connected to one end of the leftmost hole-protecting steel pipe 5 with an internal thread 51, and the microseismic sensor 7, the mounting base 4, and the 10 hole-protecting steel pipes 5 are pushed into the borehole 2 as a whole, and the rightmost hole-protecting steel pipe 5 extends outward from the hole mouth by 150 mm; the length of the microseismic sensor 7 is 80 mm, the inner diameter of the bolt hole 71 is 7 mm, and the depth is 15 mm; the length of the hexagonal nut 8 is 7.5 mm, and the nominal diameter is 150 mm.

[0044] S4: Borehole 2 is sealed and grouting is performed;

[0045] The borehole 2 is sealed with epoxy resin curing agent 10, and then grouting reinforcement is performed in the hole protection steel pipe 5 and the annulus of the borehole 2 by split grouting. The grouting liquid volume V is calculated as follows:

[0046]

[0047] Bring in the data and get:

[0048]

[0049] V=1.5V*=153.75L

[0050] S5: After the grouting liquid is completely solidified, the microseismic sensor 7 is connected to the collector through the signal cable 9, and hammering is performed at a distance of 1 meter from the borehole. The installation coupling quality of the microseismic sensor in the borehole is detected according to the quality of the hammering waveform signal monitored by the microseismic sensor. When the peak value of the hammering waveform is 10 times higher than the average amplitude of the background noise waveform, it indicates that the installation coupling quality meets the standard and microseismic monitoring is performed;

[0051] S6: Recover the microseismic sensor 7;

[0052] After the microseismic monitoring is completed, the sensor recovery rod is used to extend into the hole-protecting steel pipe 5, and the microseismic sensor 7 is rotated to remove, thereby completing the recovery of the microseismic sensor 7; the sensor recovery rod comprises: a hollow push rod 14, a sensor carrying container 12 which matches the microseismic sensor 7 is provided at the front end of the push rod 14, and a hexagonal nut container 13 which matches the hexagonal nut 8 is provided at one end of the sensor carrying container 12 close to the push rod 14; an extension rod 15 which is threadedly connected to the end of the push rod 14 away from the microseismic sensor 7 is provided, and the sensor recovery rod is used to extend into the hole-protecting steel pipe 5, and the signal cable 9 is passed through the hollow push rod 14 and the extension rod 15, and the sensor carrying container 12 and the hexagonal nut container 13 are respectively mounted on the microseismic sensor 7 and the hexagonal nut 8, and the microseismic sensor 7 can be separated from the sensor mounting base 4 by rotating the extension rod 15.

[0053] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A drilling retrievable microseismic sensor installation method, characterized in that: The steps include: S1: Make the sensor installation base (4) and the hole-protecting steel pipe (5); the details are as follows: select an outer diameter of d a , length l d , a steel pipe with a wall thickness of e is filled with cement as a sensor mounting base (4), and a bolt (11) is cast at the center of the front end of the sensor mounting base (4), and an external thread is set at the front end of the steel pipe of the sensor mounting base (4); n threads with an outer diameter of d are selected a , length l h A steel pipe with a wall thickness of e is used as a hole-protecting steel pipe (5), one end of the hole-protecting steel pipe (5) is provided with an internal thread (51), and the other end is provided with an external thread (52), and the length of the external thread provided on the steel pipe of the sensor mounting base (4) is The lengths of the inner thread (51) and the outer thread (52) of the hole-protecting steel pipe (5) are both The bolt (11) has a length of l1 and an outer diameter of d1; S2: construct a borehole (2) with a length of L and a diameter of D on the rock mass (1) in the monitoring area; S3: The microseismic sensor (7), the mounting base (4), and the hole-protecting steel pipe (5) are assembled and placed in the borehole; specifically, the microseismic sensor (7) is provided with a bolt hole (71) at the bottom and a hexagonal nut (8) at the front end, and a signal cable (9) is provided at the front end of the hexagonal nut (8). The microseismic sensor (7) is connected to the bolt (11) of the mounting base (4) through the bolt hole (71), and n hole-protecting steel pipes (5) are threadedly connected in sequence. The front end of the mounting base (4) on which the microseismic sensor (7) is installed is threadedly connected to one end of the leftmost hole-protecting steel pipe (5) provided with an internal thread (51), and the microseismic sensor (7), the mounting base (4), and the n hole-protecting steel pipes (5) are pushed into the borehole (2) as a whole, and the rightmost hole-protecting steel pipe (5) protrudes outward from the hole mouth by a length of l; The length of the microseismic sensor (7) is l s The inner diameter of the bolt hole (71) is d1 and the depth is l1; the length of the hexagonal nut (8) is l s1 , nominal diameter is d s1 ; Before the microseismic sensor (7) is connected to the bolt (11) of the mounting base (4), a coupling agent (6) is applied to the bottom of the microseismic sensor (7); S4: Drilling hole (2) is plugged and grouting is performed; specifically, the opening of the drilling hole (2) is plugged with a curing agent (10), and then grouting reinforcement is performed in the annulus of the hole protection steel pipe (5) and the drilling hole (2) by a split grouting method; the grouting liquid volume V is calculated as follows: V = 1.5V*; S5: Connect the data collector and conduct microseismic monitoring; S6: Recover the microseismic sensor (7).

2. The drilling retrievable microseismic sensor installation method according to claim 1, characterized in that: Step S5 is specifically as follows: after the grouting liquid is completely solidified, the microseismic sensor (7) is connected to the acquisition instrument via the signal cable (9), and the microseismic monitoring is performed for testing.

3. The drilling retrievable microseismic sensor installation method according to claim 1, characterized in that: Step S6 is specifically as follows: after the microseismic monitoring is completed, a sensor recovery rod is used to extend into the hole-protecting steel pipe (5), and the microseismic sensor (7) is rotated and removed, thereby completing the recovery of the microseismic sensor (7).

4. The drilling retrievable microseismic sensor installation method according to claim 3, characterized in that: In step S6, the sensor recovery rod comprises: a hollow push rod (14), a sensor carrying container (12) matching with the microseismic sensor (7) is provided at the front end of the push rod (14), a hexagonal nut container (13) matching with the hexagonal nut (8) is provided at one end of the sensor carrying container (12) close to the push rod (14), and an extension rod (15) threadedly connected to the hexagonal nut (8) is provided at one end of the push rod (14) away from the microseismic sensor (7); the sensor recovery rod is inserted into the hole-protecting steel pipe (5), the signal cable (9) passes through the hollow push rod (14) and the extension rod (15), the sensor carrying container (12) and the hexagonal nut container (13) are respectively mounted on the microseismic sensor (7) and the hexagonal nut (8), and the extension rod (15) is rotated to separate the microseismic sensor (7) from the sensor mounting base (4).

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