A device for monitoring the horizontal displacement of surrounding rock adjacent to the side wall of a large underground cavern

Abstract

The invention discloses a surrounding rock horizontal displacement monitoring device adjacent to the side wall of a large underground cavern, comprising a flexible inclinometer; after the excavation of the surrounding rock of the underground cavern top arch is completed, construction holes are excavated on both sides of the top of the underground cavern, and then a borehole is vertically drilled downward at the bottom of the construction hole, and the flexible inclinometer is installed in the borehole. The device realizes real-time monitoring of surrounding rock deformation data during the excavation of the underground cavern.

Description

Technical Field

[0001] The invention relates to a deformation monitoring device, in particular to a surrounding rock horizontal displacement monitoring device close to a side wall of a large underground cavern. Background Art

[0002] The self-stability of the tunnel surrounding rock of soft rock or broken rock is not only poor but also short. In order to maintain the stability of the surrounding rock, it is necessary to apply system anchors and anchor cables to ensure the stability of the surrounding rock in the vicinity of the underground cavern excavation face. In order to understand the stress characteristics and displacement changes of the side wall surrounding rock during the excavation process and optimize the anchor support parameters, it is necessary to monitor the displacement deformation of the free face of the cavern side wall excavation. Traditional displacement monitoring devices mostly use the installation process of drilling-burying pipes-cement sealing. The advantage of this monitoring method is that on the one hand, it can avoid the local compression deformation of the inclinometer tube or the damage to the tube wall by sharp particles in the rock and soil, and on the other hand, it can also avoid the infiltration of debris into the inclinometer tube to affect the reliable operation of the inclinometer tube. However, this method also has obvious disadvantages: it is difficult to implement safe and effective protection measures for the monitoring instrument during the construction process. Affected by the damage of flying rocks during the blasting construction of the excavation face, the posture of the monitoring instrument is easy to change, the monitoring data has deviations that affect the data accuracy, and there are certain technical deviations in the feedback guidance of the construction site; when the rock mass undergoes a small deformation, brittle fracture is prone to occur, resulting in failure of the hole. It not only threatens the integrity of the monitoring instrument, but also affects the monitoring accuracy of the instrument.

[0003] In actual projects, inclinometers are used to monitor surrounding rock deformation. The errors are mainly concentrated in two aspects: First, the traditional monitoring method usually installs flexible inclinometers step by step on the side walls of the cavern excavation surface. The equipment is installed step by step with the progress of cavern excavation, which has a certain lag and cannot reflect the actual deformation of the surrounding rock in a timely and accurate manner; second, inclinometer tubes are pre-buried in the borehole. Since the inclinometer tubes are mostly made of PVC materials, their deformation stability is poor. The bottom is squeezed by the surrounding rock for a long time, which can easily cause a certain offset at the joint of the pipe section, making it difficult for the inclinometer to maintain a vertical state. The measured data will have deviations that affect the data accuracy. Therefore, it is very necessary to choose appropriate monitoring instruments and monitoring methods. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a surrounding rock horizontal displacement monitoring device adjacent to the side wall of a large underground cavern, which can realize real-time monitoring of surrounding rock deformation data during the excavation of the underground cavern.

[0005] To achieve the above-mentioned purpose, the surrounding rock horizontal displacement monitoring device adjacent to the side wall of a large underground cavern described in the present invention includes a flexible inclinometer; after the excavation of the surrounding rock of the underground cavern top arch is completed, construction holes are excavated on both sides of the top of the underground cavern, and then a borehole is vertically drilled downward at the bottom of the construction hole, and the flexible inclinometer is installed in the borehole.

[0006] The flexible inclinometer comprises a plurality of inclinometer pipe sections, wherein two adjacent inclinometer pipe sections are connected by a nut-type metal hose, and a limiter is installed on the side of the inclinometer pipe section.

[0007] The end of the inclinometer pipe section is provided with an external thread, and the end of the nut-type metal hose is provided with a hexagonal cap nut matched with the external thread.

[0008] The limiter is installed in the middle of the inclinometer pipe section.

[0009] Both ends of the inclinometer pipe section are provided with cable reserved holes, and a data cable passes through the cable reserved holes and is connected to a data acquisition device, and the data acquisition device is arranged in the construction hole.

[0010] A metal mesh is arranged outside the middle corrugated pipe of the nut type metal hose.

[0011] The limiter comprises two limit blocks, wherein one end of the two limit blocks is provided with a first groove, the first grooves on the two limit blocks are buckled to form a through hole, and the inclinometer pipe section passes through the through hole, and the other end of the two limit blocks is provided with a second groove, and a pulley and a connecting rod are provided in the second groove, wherein the pulley is sleeved on the connecting rod, and the end of the connecting rod is connected to the inner wall of the second groove, and metal gaskets are provided on the side surfaces of the two limit blocks, wherein a rubber gasket is provided between the metal gaskets on the two limit blocks, and wherein the metal gaskets and the rubber gaskets on the two limit blocks are connected by nuts and bolts.

[0012] It also includes a grouting hose, which is inserted into the gap between the stopper and the inclinometer pipe section and the borehole.

[0013] The present invention has the following beneficial effects:

[0014] During the specific operation of the surrounding rock horizontal displacement monitoring device adjacent to the side wall of a large underground cavern described in the present invention, the flexible inclinometer is installed and arranged inside the rock mass on both sides of the cavern excavation side wall, and the overall displacement deformation monitoring of the surrounding rock can be started before the surrounding rock at the bottom of the cavern is excavated. This has a more accurate and effective monitoring effect on the overall displacement deformation of the surrounding rock of the underground cavern, can more truly reflect the displacement changes and mechanical behavior of the surrounding rock during the actual excavation process, and provide more effective data for the surrounding rock support of the cavern side wall.

[0015] Furthermore, the present invention is provided with a limiter to keep the flexible inclinometer in a relatively vertical state during the drilling installation process. Unlike the traditional fixing method of directly inserting the flexible inclinometer into the inclinometer tube in sequence and then putting it into the borehole, the flexible inclinometer cannot maintain a good independent deformation posture, which has a certain impact on the data collection work inside the inclinometer tube, especially in large deformation projects. The application is subject to certain restrictions. In view of this defect, the present invention uses a limiter and a nut-type metal hose to fix and splice the flexible inclinometer. Since the nut-type metal hose itself has good toughness and wear resistance, it has good deformation under the premise of ensuring that the flexible inclinometer maintains a vertical posture, so that each inclinometer pipe section has a relatively independent monitoring state, which can better reflect the deformation of the surrounding rock at different elevations in the monitoring area.

[0016] Furthermore, the present invention evenly injects grout into the gap between the flexible inclinometer and the borehole through the grouting hose. Compared with the traditional installation method of installing the inclinometer on the excavation face and then spraying a layer of mortar protection on its surface, it can effectively protect the monitoring instrument from being damaged by flying rocks caused by blasting during section construction, thereby ensuring the effectiveness and accuracy of the monitoring behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the installation arrangement of the present invention in an underground cavern 1 project;

[0018] Figure 2 for Figure 1 Cross-section view in the AA direction;

[0019] Figure 3 It is a schematic diagram of the flexible inclinometer 5 of the present invention;

[0020] Figure 4 It is a schematic diagram of the structure of the limiter 12 in the present invention;

[0021] Figure 5 It is a schematic diagram of the structure of the nut type metal hose 9 in the present invention.

[0022] Among them, 1 is an underground cavern, 2 is a cavern side wall, 3 is a construction hole, 4 is a drill hole, 5 is a flexible inclinometer, 6 is a thread, 7 is a cable reserved hole, 8 is a data cable, 9 is a nut-type metal hose, 10 is a hexagonal cap nut, 11 is a metal mesh, 12 is a limiter, 13 is a pulley, 14 is a connecting rod, 15 is a metal gasket, 16 is a bolt, 17 is a nut, 18 is a rubber pad, 19 is a grouting hose, and 20 is mortar. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0024] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0025] refer to Figures 1 to 5 , the surrounding rock horizontal displacement monitoring device adjacent to the side wall of a large underground cavern according to the present invention comprises a flexible inclinometer 5;

[0026] After the excavation of the top arch surrounding rock of the underground cavern 1 is completed, a construction hole 3 is excavated on both sides of the top of the underground cavern 1, and then a borehole 4 is vertically drilled downward at the bottom of the construction hole 3, and a flexible inclinometer 5 is installed in the borehole 4.

[0027] The construction hole 3 is excavated outward along the arch foot of the underground cavern 1. The size of the construction hole 3 is 2mX2.5mX2m (widthXheightXlength). The excavation reference plane of the borehole 4 is set at a position 0.5m away from the side wall of the cavern. A geological drilling machine with a diameter of 110mm is used for full-section coring drilling operations to keep the inner wall of the borehole 4 smooth. The depth of the borehole 4 is selected according to the on-site monitoring design requirements.

[0028] The flexible inclinometer 5 includes a plurality of inclinometer pipe sections, wherein two adjacent inclinometer pipe sections are connected by a nut-type metal hose 9, and a limiter 12 is installed on the side of the inclinometer pipe section to ensure that the inclinometer pipe section maintains a vertical state in the borehole 4.

[0029] The diameter of the inclinometer pipe section is 30 mm and the length is 1 m, wherein the end of the inclinometer pipe section is provided with an external thread, the end of the nut-type metal hose 9 is provided with a hexagonal cap nut 10 matching the external thread, and the limiter 12 is installed in the middle of the inclinometer pipe section to ensure that the flexible inclinometer 5 remains in a vertical state during the installation process of the drilling hole 4.

[0030] Both ends of the inclinometer pipe section are provided with cable reserved holes 7 with a diameter of 5 mm. A data cable 8 passes through the cable reserved holes 7 and is connected to a data acquisition device, which is arranged in the construction hole 3 .

[0031] The nut-type metal hose 9 includes a hexagonal cap nut 10 and a metal mesh 11 arranged outside the middle bellows of the hexagonal cap nut 10, and the thickness of the metal mesh 11 is 3 mm.

[0032] The limiter 12 includes two limit blocks, wherein one end of the two limit blocks is provided with a first groove, the first grooves on the two limit blocks are buckled to form a through hole, and the inclinometer pipe section passes through the through hole, and the other end of the two limit blocks is provided with a second groove, and a pulley 13 and a connecting rod 14 are provided in the second groove, wherein the pulley 13 is sleeved on the connecting rod 14, and the end of the connecting rod 14 is connected to the inner wall of the second groove, and metal gaskets 15 are provided on the side surfaces of the two limit blocks, wherein a rubber gasket 18 is provided between the metal gaskets 15 on the two limit blocks, wherein the metal gaskets 15 and the rubber gaskets 18 on the two limit blocks are connected by nuts 17 and bolts 16.

[0033] When assembling the flexible inclinometer 5, when the pipe reaches halfway down the borehole 4, align the two limit blocks with the middle of the inclinometer pipe section and close them, and use bolts 16 and nuts 17 to connect the metal gasket 15 and the rubber gasket 18.

[0034] When the flexible inclinometer 5 is assembled downward along the borehole 4 in sequence to reach the design elevation requirement, a grouting hose 19 is used to evenly pour mortar 20 along the gap between the limiter 12 and the inclinometer pipe section and the borehole 4 until it reaches the orifice of the borehole 4. The grouting hose 19 uses a flexible hose with an inner diameter of 15 mm and an outer diameter of 20 mm, and the mortar 20 uses small-particle concrete.

[0035] In order to ensure that each inclinometer pipe section maintains an independent working state in the borehole 4 and to prevent the data cable 8 from being damaged, the nut-type metal hose 9 is made of stainless steel. When selecting the stopper 12, the pulley 13 and the metal gasket 15, alloy materials with high hardness and corrosion resistance should be selected as much as possible.

[0036] It should be noted that the flexible inclinometer 5 used in the present invention is an intelligent monitoring device based on a MEMS three-axis acceleration sensor. Compared with traditional inclinometers, the three-dimensional flexible inclinometer can directly output three-dimensional spatial coordinates, realize "true" three-dimensional monitoring, and maintain continuous monitoring in time and space; compared with traditional displacement meter equipment, the flexible inclinometer has various protection measures, which can be specially protected against problems such as static electricity and lightning strikes that may cause equipment failure. By cascading multiple sensors and installing them in the inclinometer hole, the three-dimensional continuous deformation of the inclinometer hole can be sensed, and it has a wide range of applications in reservoir dams, slopes, geological disasters and other field scenarios.

[0037] In order to maintain good toughness and mobility of each inclinometer pipe section in the borehole 4, the present invention adopts a nut-type metal hose 9 to connect the upper and lower inclinometer pipe sections, ensuring that adjacent inclinometer pipe sections have a larger range of deformation in the horizontal direction, which can more accurately reflect the deformation of the surrounding rock of the monitoring end face.

Claims

1. A device for monitoring the horizontal displacement of surrounding rock adjacent to the side wall of a large underground cavern, characterized in that: It comprises a flexible inclinometer (5); after the excavation of the top arch surrounding rock of the underground cavern (1) is completed, a construction hole (3) is excavated on both sides of the top of the underground cavern (1), and then a borehole (4) is vertically drilled downward at the bottom of the construction hole (3), and the flexible inclinometer (5) is installed in the borehole (4); The flexible inclinometer (5) comprises a plurality of inclinometer pipe sections, wherein two adjacent inclinometer pipe sections are connected via a nut-type metal hose (9), and a limiter (12) is installed on the side of the inclinometer pipe section; The end of the inclinometer pipe section is provided with an external thread, and the end of the nut-type metal hose (9) is provided with a hexagonal cap nut (10) matching the external thread; A metal mesh (11) is arranged outside the middle corrugated pipe of the nut-type metal hose (9); The stopper (12) comprises two stop blocks, wherein one end of each of the two stop blocks is provided with a first groove, the first grooves on the two stop blocks are buckled together to form a through hole, and the inclinometer pipe section passes through the through hole, and the other end of each of the two stop blocks is provided with a second groove, a pulley (13) and a connecting rod (14) are provided in the second groove, wherein the pulley (13) is sleeved on the connecting rod (14), and the end of the connecting rod (14) is connected to the inner wall of the second groove, and metal gaskets (15) are provided on the side surfaces of the two stop blocks, wherein a rubber gasket (18) is provided between the metal gaskets (15) on the two stop blocks, and wherein the metal gaskets (15) and the rubber gaskets (18) on the two stop blocks are connected via nuts (17) and bolts (16).

2. The device for monitoring the horizontal displacement of surrounding rock adjacent to the side wall of a large underground cavern according to claim 1, characterized in that: The stopper (12) is installed at the middle part of the inclinometer pipe section.

3. The device for monitoring the horizontal displacement of surrounding rock adjacent to the side wall of a large underground cavern according to claim 1, characterized in that: Both ends of the inclinometer pipe section are provided with cable reserved holes (7), and a data cable (8) passes through the cable reserved holes (7) and is connected to a data acquisition device, and the data acquisition device is arranged in the construction hole (3).

4. The device for monitoring horizontal displacement of surrounding rock adjacent to the side wall of a large underground cavern according to claim 1, characterized in that: It also includes a grouting hose (19), which is inserted into the gap between the stopper (12), the inclinometer pipe section and the borehole (4).

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