One-hole multi-point three-dimensional disturbance stress testing system based on strain monitoring

Abstract

The utility model provides a one-hole multi-point three-dimensional disturbance stress test system based on strain monitoring, which comprises a strain signal acquisition instrument arranged in a tunnel; each hollow inclusion sensor comprises a connecting ring body part, three strain rosettes, a signal acquisition part and a temperature compensation strain gauge, the connecting ring body parts are sequentially and adjacently arranged in the drill hole in the length direction of the drill hole, and the three strain rosettes are arranged on the connecting ring body parts at equal intervals in the circumferential direction of the connecting ring body parts; the signal acquisition pieces are in communication connection with the three strain rosettes, the temperature compensation strain gauges are arranged on the inner wall of the connecting ring body piece and are in communication connection with the signal acquisition pieces, and one signal acquisition piece close to the tunnel is connected with the strain signal acquisition instrument; and the grouting hose sequentially penetrates out of the interiors of the connecting ring body pieces in the length direction of the drill hole. According to the one-hole multi-point three-dimensional disturbance stress test system, one-hole multi-point sequential measurement is realized, and the monitoring space and the monitoring cost are greatly saved.

Description

Technical Field

[0001] The utility model belongs to the technical field of rock mass engineering, and particularly relates to a one-hole multi-point three-dimensional disturbance stress testing system based on strain monitoring. Background Art

[0002] Before underground engineering excavation and underground energy extraction, the rock mass maintains balance under the action of natural stress. With the impact of the project, the internal stress of the surrounding rock changes, and when the stress exceeds its strength, the surrounding rock begins to fail. It can be considered that the change of surrounding rock stress is the fundamental driving force for the deformation and failure of tunnel or roadway surrounding rock. For this reason, monitoring the change of surrounding rock stress has always been the focus, difficulty and hot spot of existing research.

[0003] There are currently drilling axial stress gauges, three-way solid matrix stress gauges, and measuring instruments based on fiber gratings or electrical signals for disturbance stress testing. Among them, measuring instruments based on electrical signals are widely used on site due to their low cost, simple acquisition, and simple data processing. However, in-depth research has found that most of the existing electrical signal-based testing equipment has evolved from the original ground stress testing equipment, and can usually only monitor a single point in the hole, and cannot achieve multi-point monitoring, so it is impossible to obtain stress changes at different depths of the surrounding rock. If more points are to be arranged, it is necessary to add more signal acquisition equipment with more acquisition channels, which leads to higher requirements for monitoring space and increased monitoring costs.

[0004] That is, how to provide a one-hole multi-point three-dimensional disturbance stress testing system based on strain monitoring to realize one-hole multi-point sequential measurement, greatly save monitoring space and monitoring costs, and realize the monitoring of disturbance stress at different depths of surrounding rock is a technical problem that technical personnel in this field urgently need to solve. Utility Model Content

[0005] The technical problem to be solved by the utility model is that the electrical signal testing equipment for monitoring the stress change of the surrounding rock in the prior art can usually only monitor a single point in the hole, while multi-point monitoring by adding signal acquisition equipment with more acquisition channels is likely to increase the monitoring space requirements and monitoring costs.

[0006] In order to solve the above problems, the utility model provides a one-hole multi-point three-dimensional disturbance stress testing system based on strain monitoring, which is installed in a tunnel, and a borehole is opened on the wall of the tunnel. The one-hole multi-point three-dimensional disturbance stress testing system includes: a strain signal collector, which is installed in the tunnel; a plurality of hollow inclusion sensors, each of which includes a connecting ring body, three strain flowers, a signal acquisition component and a temperature compensation strain gauge, and a plurality of the connecting ring bodies are arranged in the borehole in sequence along the length direction of the borehole, and two adjacent connecting ring bodies are connected to each other, and the three strain flowers are arranged along the connecting ring body. The connecting ring bodies are arranged equidistantly on the connecting ring body in the circumferential direction, the signal acquisition component is fixed on the inner wall of the connecting ring body, the signal acquisition component is communicatively connected with the three strain flowers, the temperature compensation strain gauge is arranged on the inner wall of the connecting ring body and is communicatively connected with the signal acquisition component, one of the several signal acquisition components close to the tunnel is connected with the strain signal acquisition instrument, and two adjacent signal acquisition components are connected to each other; a grouting hose, one end of the grouting hose is located in the tunnel, and the other end of the grouting hose passes through the inside of several connecting ring bodies in sequence along the length direction of the borehole.

[0007] As a further technical solution of the utility model, the connecting ring body comprises: a PVC connecting pipe; a first rigid end ring, one end of which is threadedly connected to the PVC connecting pipe; an outer ring of the enclosure, one end of which is connected to the other end of the first rigid end ring, and three strain flowers are arranged on the outer ring of the enclosure at equal distances along the circumferential direction of the outer ring of the enclosure; an inner ring of the enclosure, one end of which is threadedly connected to the other end of the first rigid end ring, the inner ring of the enclosure is located inside the outer ring of the enclosure, the signal acquisition component is fixed to the inner wall of the inner ring of the enclosure, and the temperature compensation strain gauge is adhered to the inner wall of the inner ring of the enclosure; a second rigid end ring, the second rigid end ring is threadedly connected to the other end of the outer ring of the enclosure and the other end of the inner ring of the enclosure; wherein the second rigid end ring of one of the two adjacent connecting ring bodies close to the tunnel is connected to the PVC connecting pipe of one of the connecting ring bodies far away from the tunnel.

[0008] As a further technical solution of the utility model, the signal acquisition component includes: a signal acquisition card, the signal acquisition card is fixed on the inner wall of the inner ring of the enclosure, the temperature compensation strain gauge is communicatively connected with the signal acquisition card; a signal monitoring wire, one end of the outer ring of the enclosure is provided with three routing grooves, the three routing grooves are equidistantly arranged along the circumferential direction of the outer ring of the enclosure, the other end of the first rigid end ring is provided with three reserved grooves, the three reserved grooves are equidistantly arranged along the circumferential direction of the first rigid end ring, one strain flower and a corresponding routing groove and a corresponding reserved groove are all located on the same straight line, the distance between one strain flower and a corresponding routing groove is 5 mm, one end of the signal monitoring wire is connected with the strain flower, and the other end of the signal monitoring wire passes through the routing groove, the reserved groove and the signal acquisition card in sequence; a signal connecting line, the signal acquisition cards of two adjacent signal acquisition components are connected by a signal connecting line, and the signal acquisition card of a signal acquisition component close to the tunnel is connected to the strain signal acquisition instrument by a signal connecting line.

[0009] As a further technical solution of the utility model, the strain rosette includes: three monitoring strain gauges, one ends of the three monitoring strain gauges are connected to each other, and two adjacent monitoring strain gauges are arranged at an angle of 45°.

[0010] As a further technical solution of the utility model, the wiring groove is filled with epoxy resin glue.

[0011] As a further technical solution of the utility model, epoxy resin glue is provided at the connection between the PVC connecting pipe and the first rigid end ring, the connection between the first rigid end ring and the outer ring of the enclosure, the connection between the first rigid end ring and the inner ring of the enclosure, the connection between the second rigid end ring and the outer ring of the enclosure, the connection between the second rigid end ring and the inner ring of the enclosure, and the connection between the second rigid end ring and the PVC connecting pipe.

[0012] As a further technical solution of the utility model, the outer diameter of the PVC connecting pipe is 63 mm and the wall thickness is 3 mm.

[0013] As a further technical solution of the utility model, the outer diameter of the outer ring of the enclosure is 50 mm and the wall thickness is 5 mm.

[0014] As a further technical solution of the utility model, the outer diameter of the inner ring of the package is 33 mm and the wall thickness is 3 mm.

[0015] As a further technical solution of the utility model, the outer ring of the package is made of epoxy resin material; the inner ring of the package is made of stainless steel material.

[0016] Beneficial effects:

[0017] The utility model provides a one-hole multi-point three-dimensional disturbance stress test system based on strain monitoring, which is installed in a tunnel. A borehole is opened on the wall of the tunnel. The one-hole multi-point three-dimensional disturbance stress test system includes a strain signal acquisition instrument, a plurality of hollow package sensors and a grouting hose. Three strain rosettes are arranged equidistantly on the outer wall of the connecting ring body along the circumferential direction of the connecting ring body, that is, the three strain rosettes are arranged at 0°, 120°, and 240° of the cylinder axis of the connecting ring body respectively, so as to set three measuring points, and the strain rosettes at each measuring point are used to measure the Normal stress in two directions and shear stress in one direction are measured, so as to monitor the three-dimensional disturbance stress of each measuring point; the temperature compensation strain gauge is arranged on the inner wall of the connecting ring body, so that the temperature compensation strain gauge is deformed only under the action of temperature and is not affected by the disturbance stress, so as to perform temperature compensation through the temperature compensation strain gauge; several connecting ring bodies are arranged adjacent to each other in the borehole along the length direction of the borehole, and are connected to each other through two adjacent connecting ring bodies, so as to connect several hollow inclusion sensors in series, so as to measure in sequence, so as to realize one hole multi-point sequential measurement. Sequential monitoring can be performed without increasing the acquisition channels, which greatly saves the monitoring space and monitoring costs, and realizes the monitoring of disturbance stress at different depths of the surrounding rock; the signal acquisition component is fixed on the inner wall of the connecting ring body, and the signal acquisition component is connected to the three strain rosettes and the temperature compensation strain gauge for communication. One of the several signal acquisition components close to the tunnel is connected to the strain signal acquisition instrument installed in the tunnel, and the two adjacent signal acquisition components are connected to each other to collect the signals of the three strain rosettes and the temperature compensation strain gauge through the signal acquisition component, and transmit the signals sequentially to the strain signal acquisition instrument; one end of the grouting hose is located in the tunnel, and the other end of the grouting hose sequentially passes through the inside of several connecting ring bodies along the length direction of the borehole. When conducting on-site monitoring, the depth of the monitored surrounding rock and the number of measuring points can be determined first, and several hollow inclusion sensors can be connected in sequence. Then, holes are drilled in the tunnel wall, and several connected hollow inclusion sensors are installed in the borehole. Cement mortar can be injected into the borehole through the grouting hose, so that several hollow inclusion sensors are coupled with the tunnel surrounding rock, which is convenient for measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the structure of a hollow package sensor provided in an embodiment of the utility model;

[0020] Figure 2 A schematic diagram of the structure of a one-hole multi-point three-dimensional disturbance stress testing system provided by an embodiment of the utility model;

[0021] Figure 3 A schematic diagram of the connection of two hollow enclosure sensors provided in an embodiment of the utility model;

[0022] Figure 4 A schematic diagram of the structure of the outer ring of the enclosure provided in an embodiment of the utility model;

[0023] Figure 5 A schematic diagram of the arrangement of the outer ring of the enclosure and the strain gauge provided in an embodiment of the utility model;

[0024] Figure 6 A cross-sectional view of the outer ring of the enclosure provided by an embodiment of the utility model;

[0025] Figure 7 A right side view of a first rigid end ring provided in an embodiment of the utility model (the length is marked in mm);

[0026] Figure 8 Schematic diagram of the principle of measuring disturbance stress by the stress relief method provided in the embodiment of the utility model;

[0027] Reference numerals:

[0028] 1. Tunnel;

[0029] 2. Drilling;

[0030] 3. Strain signal acquisition instrument;

[0031] 4. Hollow package sensor; 41. Connecting ring body; 411. PVC connecting pipe; 412. First rigid end ring; 413. Package outer ring; 414. Package inner ring; 415. Second rigid end ring; 416. Routing groove; 417. Reserved groove; 42. Strain flower; 421. Monitoring strain gauge; 43. Signal acquisition component; 431. Signal acquisition card; 432. Signal monitoring wire; 433. Signal connecting wire; 44. Temperature compensation strain gauge;

[0032] 5. Grouting hose. DETAILED DESCRIPTION

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

[0034] Embodiment 1:

[0035] like Figure 1-8 As shown, the present embodiment 1 provides a one-hole multi-point three-dimensional disturbance stress testing system based on strain monitoring, which is installed in a tunnel 1, and a borehole 2 is opened on the wall of the tunnel. The one-hole multi-point three-dimensional disturbance stress testing system includes: a strain signal collector 3, and the strain signal collector 3 is installed in the tunnel 1; a plurality of hollow inclusion sensors 4, each of which includes a connecting ring body 41, three strain flowers 42, a signal acquisition component 43 and a temperature compensation strain gauge 44, and a plurality of the connecting ring bodies 41 are arranged adjacent to each other in the borehole 2 in sequence along the length direction of the borehole 2, and two adjacent connecting ring bodies 41 are connected to each other, and three strain flowers 42 are arranged on the connecting ring body 41 at equal distances along the circumferential direction of the connecting ring body 41. That is, three strain flowers 42 are respectively arranged at 0°, 120°, and 240° of the cylinder axis of the connecting ring body, the signal acquisition component 43 is fixed on the inner wall of the connecting ring body 41, the signal acquisition component 43 is communicatively connected with the three strain flowers 42, the temperature compensation strain gauge 44 is arranged on the inner wall of the connecting ring body 41 and is communicatively connected with the signal acquisition component 43, one of the signal acquisition components 43 close to the tunnel 1 is connected to the strain signal acquisition instrument 3, and two adjacent signal acquisition components 43 are connected to each other; a grouting hose 5, one end of the grouting hose 5 is located in the tunnel 1, and the other end of the grouting hose 5 passes through the inside of the several connecting ring bodies 41 in sequence along the length direction of the borehole 2.

[0036] Specifically, the utility model provides a one-hole multi-point three-dimensional disturbance stress test system based on strain monitoring, which is installed in a tunnel 1. A borehole 2 is opened on the wall of the tunnel 1. The one-hole multi-point three-dimensional disturbance stress test system includes a strain signal collector 3, a plurality of hollow inclusion sensors 4 and a grouting hose 5. Three strain rosettes 42 are arranged equidistantly on the outer wall of the connecting ring body 41 along the circumferential direction of the connecting ring body 41, that is, the three strain rosettes 42 are respectively arranged at 0°1, 20°2, and 40° of the cylinder axis of the connecting ring body 41, so as to set three measuring points, and the strain rosettes 4 at each measuring point are used to measure the stress of the connecting ring body 41. 2 measures the normal stress in two directions and the shear stress in one direction, and then monitors the three-dimensional disturbance stress of each measuring point; the temperature compensation strain gauge 44 is arranged on the inner wall of the connecting ring body 41, so that the temperature compensation strain gauge 44 is only deformed under the action of temperature and is not affected by the disturbance stress, so that temperature compensation is performed by the temperature compensation strain gauge 44; a plurality of connecting ring bodies 41 are arranged adjacent to each other in the borehole 2 along the length direction of the borehole 2, and two adjacent connecting ring bodies 41 are connected to each other to connect a plurality of hollow inclusion sensors 4 in series, so as to measure in sequence in order to realize one-hole multi-point sequential monitoring The signal acquisition component 43 is fixed on the inner wall of the connecting ring 41, and the signal acquisition component 43 is connected to the three strain rosettes 42 and the temperature compensation strain gauge 44 for communication. One of the signal acquisition components 43 close to the tunnel 1 is connected to the strain signal acquisition instrument 3 installed in the tunnel 1, and two adjacent signal acquisition components 43 are connected to each other to collect the signals of the three strain rosettes 42 and the temperature compensation strain gauge 44 through the signal acquisition component 43, and The signals are transmitted sequentially to the strain signal collector 3; one end of the grouting hose 5 is located in the tunnel 1, and the other end of the grouting hose 5 is sequentially passed through the inside of several connecting ring parts 41 along the length direction of the borehole 2. When conducting on-site monitoring, the depth of the monitored surrounding rock and the number of measuring points can be determined first, and several hollow inclusion sensors 4 are connected in sequence. Then, holes are drilled in the wall of the tunnel 1, and the connected several hollow inclusion sensors 4 are installed into the borehole 2. Cement mortar can be injected into the borehole 2 through the grouting hose 5, so that the several hollow inclusion sensors 4 are coupled with the surrounding rock of the tunnel 1, which is convenient for measurement.

[0037] The electrical measurement principle of the strain gauge 42 is as follows: when an object is deformed by an external force, the strain gauge 42 will produce a corresponding deformation, thereby causing a slight change in the resistance value of the strain gauge 42. This slight resistance causes a voltage change, which can be detected and recorded by a connected measurement circuit, thereby obtaining the strain condition of the object surface. The monitoring principle of the test system of this embodiment is the stress relief method, such as Figure 8 As shown, it is mainly divided into the following steps:

[0038] (1) When the surrounding rock is not subjected to stress, the stress and strain in the unit cell are both 0;

[0039] (2) Under the action of natural stress, the stress in the unit cell is σ0 and the initial strain is ε0;

[0040] (3) drilling a hole at the measuring point to arrange the disturbance stress test system to monitor the disturbance stress of the surrounding rock, and the unit body strain increases by Δε0 to ε1 under the action of the initial stress σ0;

[0041] (4) After the arrangement of the disturbance stress monitoring system is completed, mortar is injected into the hole, the strain signal acquisition instrument 3 is connected, and the strain signal acquisition instrument 3 is adjusted to balance to 0, that is, only the strain increment is monitored subsequently, and it is considered that the strain and stress in the unit body are 0 at this time;

[0042] (5) During the process of engineering excavation or underground energy extraction, disturbance stress Δσ is generated d So that Δε occurs at the measuring point d The strain increment is obtained by monitoring the strain increment ε by the strain signal acquisition instrument 3. ij According to the generalized Hooke's law, the disturbance stress σ is obtained ij .

[0043] In some possible implementations, the connecting ring body 41 includes: a PVC connecting pipe 411; a first rigid end ring 412, one end of which is threadedly connected to the PVC connecting pipe 411; an outer ring 413 of the package, one end of which is connected to the other end of the first rigid end ring 412, and three strain flowers 42 are arranged on the outer ring 413 of the package at equal distances along the circumferential direction of the outer ring 413 of the package; an inner ring 414 of the package, one end of which is threadedly connected to the other end of the first rigid end ring 412, and the inner ring 414 of the package is located at Inside the outer ring 413 of the enclosure, the signal acquisition component 43 is fixed to the inner wall of the inner ring 414 of the enclosure, and the temperature compensation strain gauge 44 is pasted on the inner wall of the inner ring 414 of the enclosure; the second rigid end ring 415, the second rigid end ring 415 is threadedly connected with the other end of the outer ring 413 of the enclosure and the other end of the inner ring 414 of the enclosure; wherein the second rigid end ring 415 of one of the two adjacent connecting ring parts 41 close to the tunnel 1 is connected to the PVC connecting pipe 411 of one of the connecting ring parts 41 far away from the tunnel 1. The length of the PVC connecting pipe 411 can be adjusted according to the monitoring requirements.

[0044] This is because one end of the first rigid end ring 412 is threadedly connected to the PVC connecting pipe 411, and the other end is connected to one end of the outer ring 413 of the package, and one end of the inner ring 414 of the package is threadedly connected to the other end of the first rigid end ring 412, and the inner ring 414 of the package is located inside the outer ring 413 of the package, and the second rigid end ring 415 is threadedly connected to the other end of the outer ring 413 of the package and the other end of the inner ring 414 of the package, so that the PVC connecting pipe 411, the outer ring 413 of the package and the inner ring 414 of the package are combined into a An integral and hollow enclosure double-layer composite structure; a complete second rigid end ring 415 is connected to the rightmost side of the enclosure outer ring 413, and the second rigid end ring 415 of the connecting ring body 41 close to the tunnel 1 of the two adjacent connecting ring body parts 41 is connected to the PVC connecting pipe 411 of the connecting ring body part 41 far away from the tunnel 1, and can be connected to the PVC connecting pipe 411 of the next (from left to right) hollow enclosure sensor 4 through the second rigid end ring 415 to realize one-hole multi-point monitoring; and the connection methods are all structural connections, without on-site welding, and easy installation.

[0045] In some possible implementations, the signal acquisition component 43 includes: a signal acquisition card 431, the signal acquisition card 431 is fixed to the inner wall of the inner ring 414 of the package, the temperature compensation strain gauge 44 is communicatively connected to the signal acquisition card 431; a signal monitoring wire 432, one end of the outer ring 413 of the package is provided with three routing grooves 416, the three routing grooves 416 are equidistantly arranged along the circumferential direction of the outer ring 413 of the package, the other end of the first rigid end ring 412 is provided with three reserved grooves 417, the three reserved grooves 417 are equidistantly arranged along the circumferential direction of the first rigid end ring 412, and one strain flower 42 is connected to a corresponding routing groove 41 6 and a corresponding reserved groove 417 are located on the same straight line, a distance between a strain flower 42 and a corresponding wiring groove 416 is 5 mm, one end of the signal monitoring wire 432 is connected to the strain flower 42, and the other end of the signal monitoring wire 432 passes through the wiring groove 416 and the reserved groove 417 in sequence to be connected to the signal acquisition card 431; a signal connecting line 433, the signal acquisition cards 431 of two adjacent signal acquisition components 43 are connected through the signal connecting line 433, and the signal acquisition card 431 of a signal acquisition component 43 close to the tunnel 1 is connected to the strain signal acquisition instrument 3 through the signal connecting line 433.

[0046] This is because, by fixing the signal acquisition card 431 on the inner wall of the inner ring 414 of the package body, it is possible to avoid sensor misconnection during the monitoring process, which may cause damage to the signal acquisition card 431; the three routing grooves 416 opened at one end of the outer ring 413 of the package body are equidistantly arranged along the circumferential direction of the outer ring 413 of the package body, and the three reserved grooves 417 opened at the other end of the first rigid end ring 412 are equidistantly arranged along the circumferential direction of the first rigid end ring 412; a strain flower 42 and a corresponding routing groove 416 and a corresponding reserved groove 417 are all located on the same straight line; one end of the signal monitoring wire 432 is connected to the strain flower 42, and the other end passes through the routing groove 416 and the reserved groove 417 in turn to be connected to the signal acquisition card 431, and can be connected to the signal acquisition card 431 through the routing groove 416 and the reserved groove 417 are used for routing to protect the signal monitoring wire 432. When connecting, the signal monitoring wire 432 passes through the routing groove 416 and the reserved groove 417. When the reserved groove 417 and the routing groove 416 are aligned, the first rigid end ring 412 can be connected to the outer ring 413 of the enclosure by a buckle; the signal acquisition cards 431 of two adjacent signal acquisition components 43 are connected by a signal connecting line 433, and the signal acquisition card 431 of a signal acquisition component 43 close to the tunnel 1 is connected to the strain signal acquisition instrument 3 through the signal connecting line 433. Signal connecting lines 433 can be left on both sides of the signal acquisition card 431 to connect the strain signal acquisition instrument 3 or the next hollow enclosure sensor 4. When making the connection, first connect the signal connection line 433 of the signal acquisition card 431 of the two hollow package sensors 4, and then connect the second rigid end ring 415 of the first hollow package sensor 4 to the PVC connecting tube 411 of the second hollow package sensor 4 to realize the data acquisition connection of the two hollow package sensors 4.

[0047] In some possible implementations, the strain gauge 42 includes: three monitoring strain gauges 421 , one ends of the three monitoring strain gauges 421 are connected to each other, and two adjacent monitoring strain gauges 421 are arranged at an angle of 45°.

[0048] Those skilled in the art can understand that one ends of the three monitoring strain gauges 421 are connected to each other, and two adjacent monitoring strain gauges 421 are arranged at an angle of 45°, so that a strain rosette 42 is formed by three monitoring strain gauges 421 spaced 45° apart to monitor the three-dimensional disturbance stress at the point.

[0049] In some possible implementations, the wiring groove 416 is filled with epoxy resin glue.

[0050] Those skilled in the art will appreciate that the wiring groove 416 is filled with epoxy resin glue to protect the signal monitoring wire 432 .

[0051] In some possible embodiments, all connections including the connection between the PVC connecting tube 411 and the first rigid end ring 412, the connection between the first rigid end ring 412 and the outer ring 413 of the enclosure, the connection between the first rigid end ring 412 and the inner ring 414 of the enclosure, the connection between the second rigid end ring 415 and the outer ring 413 of the enclosure, the connection between the second rigid end ring 415 and the inner ring 414 of the enclosure, and the connection between the second rigid end ring 415 and the PVC connecting tube 411 are provided with epoxy resin glue by coating, which can ensure the airtightness of the test system, and the epoxy resin glue is resistant to high temperature and corrosion.

[0052] In some possible implementations, the PVC connecting pipe 411 has an outer diameter of 63 mm and a wall thickness of 3 mm.

[0053] In some possible implementations, the outer diameter of the outer ring 413 of the enclosure is 50 mm and the wall thickness is 5 mm.

[0054] In some possible implementations, the outer diameter of the inner ring 414 of the enclosure is 33 mm and the wall thickness is 3 mm.

[0055] In some possible implementations, the inclusion body inner ring 413 is made of epoxy resin; and the inclusion body inner ring 414 is made of stainless steel.

[0056] It should be noted that the principle of the three-dimensional stress testing method based on strain gauges of the utility model is as follows:

[0057] (1) According to the right-hand screw principle, the basic coordinate system and the local coordinate system of the strain rosette are established, and the strain increments in the corresponding directions obtained by the three strain rosettes 42 are:

[0058]

[0059] (2) Through coordinate transformation, the strain obtained in the local coordinate system of the strain rosette 42 is converted into the strain tensor in the basic coordinate system:

[0060]

[0061] (3) According to the linear elastic theory, using the rock elastic parameters, the disturbance stress tensor can be obtained:

[0062]

[0063] Specifically, in this embodiment, three measuring points are arranged at 0°, 120°, and 240° of the axis of the outer ring of the enclosure, respectively, and are numbered A, B, and C, corresponding to m=1-3. There is a strain rosette 42 at each measuring point, which can measure the normal stress in two directions and the shear stress in one direction, such as Figure 5The three strain gauges 421 are numbered in sequence, i=1-3 respectively, and a local coordinate system of the strain gauge rosette 42 is established at the same time, and the z axis is determined according to the right-hand screw rule, as shown in Table 1.

[0064] Table 1 Strain gauge number

[0065]

[0066] In this embodiment, signal acquisition is discrete acquisition, which is achieved at a fixed time through program control. During acquisition, it is sequential acquisition, starting from the deepest measuring point of the surrounding rock, and each time the data of three measuring points, namely nine strain gauges and one temperature compensation, are collected. Since the interval time is relatively short, the data fluctuation is not large, and it can be considered as the monitoring result at the same time. Based on this, when monitoring, a borehole only needs 10 acquisition channels, realizing efficient and low-cost monitoring. The specific data processing steps are as follows:

[0067] (1) Establish a basic coordinate system, such as Figure 5 As shown;

[0068] (2) In the local coordinate system of the strain rosette, A, B, and C correspond to m = 1, 2, and 3 respectively. The strain tensor of each measuring point is:

[0069]

[0070] (3) The local coordinate system of the strain rosette at point A is consistent with the basic coordinate system. The local coordinate system of the strain rosette at point B is 120° clockwise rotated by the x-axis and z-axis compared with the basic coordinate system. The local coordinate system of the strain rosette at point C is 240° clockwise rotated by the x-axis and z-axis compared with the basic coordinate system. Take the rotation angle as θ, then the rotation matrix [β] is:

[0071]

[0072] (3) According to the coordinate change of the strain tensor, the strain state at the three measuring points can be obtained as follows:

[0073] [ε m ]=[β m ]·[ε' m ]·[β m ] T (3)

[0074] (4) Thus, the strain tensor at the point where the hollow package sensor is located is obtained as:

[0075]

[0076] (5) According to the linear elastic theory and the elastic parameters of the rock, the disturbance stress tensor can be obtained:

[0077] σij = λε kk δ ij + 2G ε ij (5)

[0078] In formula (5), δ ij When i=j, it is 1, and otherwise it is 0; λ and G are the Lame constants of the strain brick matrix, i.e., similar materials, where λ=Ev / [(1+v)(1-2v)], G=E / [2(1+v)], E is the elastic modulus of rock, and v is the Poisson's ratio of rock.

[0079] From formula (5), we can get the surrounding rock stress σ in the basic coordinate system: ij , that is, the disturbance stress σ d .

[0080] The test system provided by the utility model can realize one-hole multi-point distributed measurement of tunnel surrounding rock, and can test the stress state of different surrounding rock depths without increasing the acquisition channels. It inherits the advantages of strain gauge measurement with low cost, simple acquisition and easy data processing, and cooperates with high temperature and corrosion resistant epoxy resin glue and special structural design to realize long-term monitoring of surrounding rock disturbance stress. It adopts distributed measurement method, combines acquisition card and program design, uses the same acquisition channel to collect more points of disturbance stress data, realizes one-hole multi-point sequential measurement, greatly saves monitoring space and monitoring cost, and realizes the monitoring of disturbance stress at different depths of surrounding rock.

[0081] Finally, it should be noted that the above-mentioned embodiments are only specific implementation methods of the utility model, which are used to illustrate the technical solution of the utility model, rather than to limit it. The protection scope of the utility model is not limited thereto. Although the utility model is described in detail with reference to the above-mentioned embodiments, ordinary technicians in this field should understand that any technician familiar with the technical field can still modify the technical solution recorded in the above-mentioned embodiments within the technical scope disclosed by the utility model, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiment of the utility model. They should all be included in the protection scope of the utility model. Therefore, the protection scope of the utility model shall be based on the protection scope of the claims.

[0082] Although the implementation scheme of the utility model has been disclosed as above, it is not limited to the applications listed in the specification and implementation modes. It can be fully applied to various fields suitable for the utility model. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A one-hole multi-point three-dimensional disturbance stress testing system based on strain monitoring, installed in a tunnel, wherein the wall of the tunnel is provided with a borehole, characterized in that: The one-hole multi-point three-dimensional disturbance stress testing system comprises: A strain signal collector installed in the tunnel; A plurality of hollow inclusion sensors, each of which comprises a connecting ring body, three strain flowers, a signal acquisition component and a temperature compensation strain gauge, wherein the plurality of connecting ring bodies are arranged adjacent to each other in the borehole in sequence along the length direction of the borehole, two adjacent connecting ring bodies are connected to each other, three strain flowers are arranged equidistantly on the connecting ring body along the circumferential direction of the connecting ring body, the signal acquisition component is fixed to the inner wall of the connecting ring body, the signal acquisition component is communicatively connected to the three strain flowers, the temperature compensation strain gauge is arranged on the inner wall of the connecting ring body and is communicatively connected to the signal acquisition component, one of the plurality of signal acquisition components close to the tunnel is connected to the strain signal acquisition instrument, and two adjacent signal acquisition components are connected to each other; A grouting hose, one end of which is located in the tunnel, and the other end of which passes through the interior of a plurality of the connecting ring members in sequence along the length direction of the borehole.

2. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 1 is characterized in that: The connecting ring body comprises: PVC connecting pipe; A first rigid end ring, one end of which is threadedly connected to the PVC connecting pipe; An outer ring of the enclosure, one end of which is connected to the other end of the first rigid end ring, and three strain rosettes are arranged on the outer ring of the enclosure at equal distances along the circumferential direction of the outer ring of the enclosure; An inner ring of the package, one end of which is threadedly connected to the other end of the first rigid end ring, the inner ring of the package is located inside the outer ring of the package, the signal acquisition component is fixed to the inner wall of the inner ring of the package, and the temperature compensation strain gauge is pasted on the inner wall of the inner ring of the package; A second rigid end ring, the second rigid end ring being threadedly connected to the other end of the outer ring of the enclosure and the other end of the inner ring of the enclosure; Wherein, the second rigid end ring of one of the two adjacent connecting ring members close to the tunnel is connected to the PVC connecting pipe of one of the connecting ring members far away from the tunnel.

3. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 2 is characterized in that: The signal acquisition component comprises: A signal acquisition card, wherein the signal acquisition card is fixed to the inner wall of the inner ring of the package, and the temperature compensation strain gauge is communicatively connected with the signal acquisition card; The signal monitoring wire has three routing grooves at one end of the outer ring of the enclosure, and the three routing grooves are arranged equidistantly along the circumferential direction of the outer ring of the enclosure; the other end of the first rigid end ring has three reserved grooves, and the three reserved grooves are arranged equidistantly along the circumferential direction of the first rigid end ring; one strain flower and a corresponding routing groove and a corresponding reserved groove are all located on the same straight line; the distance between one strain flower and a corresponding routing groove is 5 mm; one end of the signal monitoring wire is connected to the strain flower, and the other end of the signal monitoring wire passes through the routing groove and the reserved groove in sequence to be connected to the signal acquisition card; A signal connection line is used to connect the signal acquisition cards of two adjacent signal acquisition components, and the signal acquisition card of a signal acquisition component close to the tunnel is connected to the strain signal acquisition instrument through a signal connection line.

4. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 3 is characterized in that: The strain rosette comprises: Three monitoring strain gauges, one ends of the three monitoring strain gauges are connected to each other, and two adjacent monitoring strain gauges are arranged at an angle of 45 degrees.

5. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 4, characterized in that: The wiring groove is filled with epoxy resin glue.

6. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 5, characterized in that: Epoxy resin glue is provided at the connection between the PVC connecting pipe and the first rigid end ring, the connection between the first rigid end ring and the outer ring of the enclosure, the connection between the first rigid end ring and the inner ring of the enclosure, the connection between the second rigid end ring and the outer ring of the enclosure, the connection between the second rigid end ring and the inner ring of the enclosure, and the connection between the second rigid end ring and the PVC connecting pipe.

7. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 6, characterized in that: The outer diameter of the PVC connecting pipe is 63 mm and the wall thickness is 3 mm.

8. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 7, characterized in that: The outer diameter of the outer ring of the enclosure is 50 mm and the wall thickness is 5 mm.

9. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 8, characterized in that: The outer diameter of the inner ring of the package is 33 mm and the wall thickness is 3 mm.

10. The one-hole multi-point three-dimensional disturbance stress testing system according to claim 9, characterized in that: The outer ring of the package is made of epoxy resin material; the inner ring of the package is made of stainless steel material.

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