Rock mass disturbance stress monitoring device and method with rigidity matching characteristic

Abstract

The invention discloses a rock mass disturbance stress monitoring device and method with a rigidity matching characteristic, and relates to the technical field of rock disturbance stress monitoring, the rock mass disturbance stress monitoring device comprises a strain rosette, a strain gauge skeleton, a flexible gas film, a temperature sensor and a data acquisition module; the flexible gas film is fixed in the strain gauge framework in an inward concave shape; the reverse side of the strain rosette is pasted on the flexible gas film, and the temperature sensor is pasted on the flexible gas film and is close to the strain rosette. A bonding material is attached to the surface of the flexible gas film, and the bonding material is determined according to the elastic modulus of the rock mass to be measured; and the data acquisition module is electrically connected with the strain rosette and the temperature sensor. The technical problem that in the prior art, a strain gauge is not matched with the rigidity of rock is solved, and the rock mass disturbance stress can be accurately and effectively transmitted to a monitoring element on the premise that hole collapse or large deformation of surrounding rock drilling does not occur by selecting proper bonding materials and flexible media and matching with continuous supporting of the flexible gas film.

Description

Technical Field

[0001] This invention relates to the field of rock disturbance stress monitoring technology, and in particular to a rock mass disturbance stress monitoring device and method with stiffness matching characteristics. Background Technology

[0002] Disturbance stress is a cause of rock mass failure and instability in underground engineering. Although stress measurement and monitoring technologies for rock masses are relatively mature both domestically and internationally, commonly used methods include hollow inclusion strain gauges, borehole stress gauges, and fiber optic gratings. However, in actual measurement, strain gauges, due to their mismatch with rock stiffness, restrict rock deformation, thus affecting measurement accuracy. Fiber optic gratings, due to their high cost, offer lower cost-effectiveness for disturbance stress monitoring with a limited number of measurement points. Summary of the Invention

[0003] To address the aforementioned technical problems in the existing technology, this invention provides a rock mass disturbance stress monitoring device and method with stiffness matching characteristics. The technical solution is as follows:

[0004] On one hand, a rock mass disturbance stress monitoring device with stiffness matching characteristics is provided, comprising: a strain rose, a strain gauge frame, a flexible gas film, a temperature sensor, and a data acquisition module; wherein, the flexible gas film is fixed inside the strain gauge frame in a concave shape, and is extruded outside the strain gauge frame after being filled with a flexible medium and expanded; the strain rose is pasted on the flexible gas film with its reverse side attached, and the temperature sensor is pasted on the flexible gas film and located close to the strain rose; the surface of the flexible gas film is coated with an adhesive material, the adhesive material being determined according to the elastic modulus of the rock mass to be tested; the data acquisition module is connected to the strain rose and the temperature sensor via a cable.

[0005] Optionally, the ratio of the elastic modulus of the cured adhesive material to the elastic modulus of the rock mass to be tested is 1 / 20 to 1 / 10.

[0006] Optionally, the adhesive material includes epoxy resin adhesive, flexible modified epoxy adhesive, and polyurethane adhesive; when the elastic modulus of the rock mass to be tested is greater than a preset threshold, the adhesive material is the epoxy resin adhesive; when the elastic modulus of the rock mass to be tested is less than or equal to the preset threshold, the adhesive material is the flexible modified epoxy adhesive or the polyurethane adhesive.

[0007] Optionally, there are multiple strain gauges, which are distributed at equal intervals along the circumference in the middle of the flexible air film; each strain gauge includes multiple strain gauges at different angles.

[0008] Optionally, a positioning bolt and a suspension pin are provided at one end of the strain gauge frame; wherein, the suspension pin is used to determine the rotation angle of the strain gauge frame; and the positioning bolt is used to adjust the installation direction of the rock mass disturbance stress monitoring device with stiffness matching characteristics.

[0009] Optionally, a glue storage chamber is provided inside the strain gauge frame, and the adhesive material is stored in the glue storage chamber.

[0010] Optionally, a valve is provided at the filling port of the flexible air membrane; the flexible medium filling the flexible air membrane includes water or air.

[0011] Optionally, multiple lead holes are provided at equal intervals along the circumference on the outer wall of the strain gauge frame, and a wire of the corresponding strain flower passes through each lead hole.

[0012] On the other hand, a monitoring method for a rock mass disturbance stress monitoring device with stiffness matching characteristics is also provided. The method includes: drilling a hole at the monitoring point on the rock mass to be tested and taking out the core sample; attaching a strain gauge to the core sample at the device installation point and placing the core sample in a constant temperature chamber for temperature calibration to obtain temperature compensation data; measuring the elastic modulus of the core sample and determining the bonding material based on the elastic modulus; filling the adhesive chamber of the strain gauge frame with the bonding material; and sending the rock mass disturbance stress monitoring device with stiffness matching characteristics to the device installation point via a mounting rod; and rotating the core sample... The rock mass disturbance stress monitoring device coats the adhesive material onto the surface of the flexible air film; the mounting rod is rotated according to the state of the pendant to ensure that the installation angle of the rock mass disturbance stress monitoring device with stiffness matching characteristics is consistent with the preset installation angle, and a flexible medium is filled into the flexible air film to cause the flexible air film to expand and squeeze out and adhere tightly to the borehole inner wall of the monitoring point; monitoring data is collected after the adhesive material solidifies, and the flexible air film support structure filled with flexible medium is maintained throughout the monitoring process, and the monitoring data is corrected based on the temperature compensation data to obtain the disturbance stress of the rock mass to be tested; the monitoring data includes temperature data and stress data.

[0013] This invention provides a rock mass disturbance stress monitoring device and method with stiffness matching characteristics. By selecting different curing adhesives, the stiffness of the adhesive shell in the measuring section of the device is adjustable. This avoids measurement errors caused by excessive adhesive stiffness constraining local deformation of the surrounding rock, while also preventing a decrease in strain transmission efficiency due to insufficient stiffness. This ensures that the rock mass disturbance stress can be effectively transmitted to the monitoring element. A concave, high-temperature resistant flexible gas film structure is employed. Different flexible media are filled according to the magnitude of the disturbance stress, causing the flexible gas film to expand and be extruded, maintaining the borehole shape in the surrounding rock and ensuring that it does not change significantly. Simultaneously, strain gauges are adhered to the surface of the surrounding rock. Furthermore, the device provided by this invention incorporates a temperature pre-compensation mechanism to effectively eliminate measurement errors caused by temperature changes, achieving long-term stable monitoring of disturbance stress. This invention alleviates the technical problem of stiffness mismatch between strain gauges and rock in existing technologies. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the overall structure of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention.

[0016] Figure 2 This is a side view of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention;

[0017] Figure 3 This is a cross-sectional schematic diagram of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention before installation;

[0018] Figure 4 This is a cross-sectional schematic diagram of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention after installation.

[0019] Figure 5 This is a flowchart of a monitoring method for a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention.

[0020] In the figure: 1. Strain gauge frame, 11. Glue storage chamber, 12. Positioning bolt, 13. Lead wire hole, 2. Strain rosette, 3. Data acquisition module, 4. Temperature sensor, 5. Suspension needle, 6. Flexible air film, 61. Valve, 7. Adhesive material. Detailed Implementation

[0021] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0022] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0023] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0024] Figure 1 A schematic diagram of the overall structure of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention. Figure 2 This is a side view of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention. Figure 3 This is a cross-sectional schematic diagram of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention before installation. Figure 4 This is a cross-sectional schematic diagram of a rock mass disturbance stress monitoring device with stiffness matching characteristics provided in an embodiment of the present invention after installation. Figures 1-4 As shown, it includes: strain gauge 2, strain gauge frame 1, flexible air film 6, temperature sensor 4, and data acquisition module 3.

[0025] Specifically, such as Figure 3 and Figure 4 As shown, the flexible gas film 6 is fixed inside the strain gauge frame 1 in a concave shape. After the flexible gas film 6 is filled with a flexible medium and expands, it is extruded to the outside of the strain gauge frame 1.

[0026] Alternatively, the flexible medium may include air or water.

[0027] Specifically, the strain gauge 2 is attached to the flexible air membrane 6 on the reverse side, and the temperature sensor 4 is attached to the flexible air membrane 6 and close to the strain gauge 2.

[0028] The surface of the flexible air film 6 is covered with an adhesive material 7, which is determined according to the elastic modulus of the rock mass to be tested.

[0029] The data acquisition module 3 is electrically connected to the strain gauge 2 and the temperature sensor 4.

[0030] Specifically, data acquisition module 3 can realize integrated acquisition of rock strain and static strain, and realize synchronous monitoring of time-dependent strain and dynamic strain of rock samples during the monitoring process.

[0031] In one optional embodiment of the present invention, the flexible air membrane 6 is a high-temperature resistant silicone rubber composite material, and saturated hot steam can be introduced into the adhesive material 7 that requires thermosetting properties. Simultaneously, the installed flexible air membrane 6 can provide support for fractured surrounding rock or soft rock, ensuring that even if the soft rock around the measuring section deforms, there is a sufficiently long support section at the measuring point to guarantee that the disturbance stress can propagate to the monitoring point.

[0032] In this embodiment of the invention, the concave flexible air film 6 is expanded and squeezed out to fit tightly against the inner wall of the borehole, which can ensure that the adhesive is thin enough so that the strain rosette 2 can directly measure the strain of the surrounding rock of the borehole.

[0033] In an optional embodiment of the present invention, the adhesive material 7 includes epoxy resin adhesive, flexible modified epoxy adhesive, and polyurethane adhesive.

[0034] When the elastic modulus of the rock mass to be tested is greater than the preset threshold, the bonding material 7 is epoxy resin adhesive;

[0035] When the elastic modulus of the rock mass to be tested is less than or equal to the preset threshold, the bonding material 7 is a flexible modified epoxy adhesive or a polyurethane adhesive.

[0036] For example, the preset threshold is 30 GPa.

[0037] It should be noted that, in the embodiments of the present invention, the adhesive material 7 is not limited to the above-mentioned types. As long as the colloid has a slightly longer solidification time and has a certain degree of fluidity, and satisfies the ratio between the adhesive material and the elastic modulus of the surrounding rock, it is acceptable.

[0038] Preferably, the ratio of the elastic modulus of the cured adhesive material 7 to the elastic modulus of the rock mass to be tested is 1 / 20 to 1 / 10. Appropriate stiffness ensures effective transmission of borehole strain without affecting the deformation of the surrounding rock.

[0039] Preferably, there are multiple strain gauges 2, which are distributed at equal intervals along the circumference in the middle of the flexible air film 6; each strain gauge 2 includes multiple strain gauges at different angles.

[0040] For example, a strain gauge 2 has four angles: 0°, 45°, 90°, and 135°. These strain gauges 2 are evenly spaced around the center of the flexible air membrane 6, with a total of three strain gauges. With a total of 12 strain gauges, a large amount of data can be obtained.

[0041] Specifically, a positioning bolt 12 and a suspension pin 5 are provided at one end of the strain gauge frame 1; wherein,

[0042] The suspension needle 5 is used to determine the rotation angle of the strain gauge frame 1;

[0043] Positioning bolt 12 is used to adjust the installation direction of the rock mass disturbance stress monitoring device with stiffness matching characteristics.

[0044] Specifically, a suspension pin 5 is provided at one end of the strain gauge frame 1. During installation, the direction of the suspension pin 5 can be observed to determine the angle of rotation of the device relative to its initial placement. After rotating the device to allow the flexible air film 6 to adhere to the adhesive material 7, the device can be rotated back to its initial position, thus revealing the direction of the strain gauge rosette 2.

[0045] Specifically, the strain gauge frame 1 is provided with a glue storage chamber 11, which stores adhesive material 7.

[0046] Specifically, a valve 61 is installed at the filling port of the flexible air membrane 6.

[0047] Specifically, the flexible air film 6 is set in the adhesive storage chamber 11 in a concave shape. The adhesive storage chamber 11 can store the adhesive material 7. After the flexible air film 6 is filled with flexible medium through the valve 61 and expands, it is squeezed out of the adhesive storage chamber 11 and adheres tightly to the inner wall of the borehole. The adhesive material 7 on the flexible air film 6 is selected according to the elastic modulus of the surrounding rock.

[0048] Specifically, multiple lead holes 13 are equally spaced along the circumference on the outer wall of the strain gauge frame 1, and a wire passing through the corresponding strain flower 2 passes through each lead hole 13.

[0049] For example, the strain gauge frame 1 has three lead holes 13 evenly distributed around its circumference. These lead holes 13 facilitate the separation of wires from different strain gauges 2, preventing the wires from tangling and knotting during the expansion and extrusion of the flexible gas film.

[0050] Figure 5 This is a flowchart illustrating a monitoring method for a rock mass disturbance stress monitoring device with stiffness matching characteristics, provided by an embodiment of the present invention. Figure 5 As shown, the method specifically includes the following steps:

[0051] Step S502: Drill holes at the monitoring points on the rock mass to be tested and extract the core samples from the drill holes.

[0052] For example, drill holes in the rock mass to be monitored, with a diameter between 75mm and 100mm, until the monitoring point is reached.

[0053] Step S504: The strain gauge is attached to the borehole core at the device installation point, and the borehole core is placed in a constant temperature chamber for temperature calibration to obtain temperature compensation data. Specifically, the temperature compensation data includes the strain change of the borehole core under a unit temperature change.

[0054] Step S506: Measure the elastic modulus of the borehole core and determine the bonding material based on the elastic modulus.

[0055] Specifically, the elastic modulus of the borehole core was measured through indoor uniaxial tests.

[0056] Step S508: Fill the adhesive chamber of the strain gauge frame with adhesive material, and send the rock mass disturbance stress monitoring device with stiffness matching characteristics to the device installation point through the installation rod; apply adhesive material to the surface of the flexible air film by rotating the rock mass disturbance stress monitoring device with stiffness matching characteristics.

[0057] Specifically, a sufficient amount of adhesive material is poured into the glue storage chamber, a specially designed mounting rod pin is inserted into the device pin, an infrared camera is fixed on the mounting rod, and the device is sent to the predetermined monitoring point.

[0058] In one optional embodiment of the present invention, the adhesive material includes epoxy resin adhesive, flexible modified epoxy adhesive, and polyurethane adhesive; the adhesive material is determined based on the elastic modulus, including:

[0059] When the elastic modulus is greater than the preset threshold, the adhesive material is determined to be epoxy resin.

[0060] When the elastic modulus is less than or equal to a preset threshold, the bonding material is determined to be a flexible modified epoxy adhesive or a polyurethane adhesive.

[0061] For example, the preset threshold is 30 GPa.

[0062] Step S510: Rotate the installation rod according to the state of the needle to ensure that the installation angle of the rock mass disturbance stress monitoring device with stiffness matching characteristics is consistent with the preset installation angle, and fill the flexible air film with flexible medium so that the flexible air film expands and squeezes out and sticks tightly to the borehole inner wall of the monitoring point.

[0063] Specifically, the mounting rod is rotated, and the device is slowly rotated several times to ensure that the adhesive material fully adheres to the flexible air film. Then, a flexible medium, such as water or air, is filled into the filling channel of the flexible air film. The concave flexible air film is then expanded and extruded, making it adhere tightly to the inner wall of the borehole.

[0064] Step S512: After the adhesive material solidifies, monitoring data is collected. The flexible air film support structure filled with flexible medium is maintained throughout the monitoring process, and the monitoring data is corrected based on temperature compensation data to obtain the disturbance stress of the rock mass to be tested. The monitoring data includes temperature data and stress data.

[0065] It is important to emphasize that the flexible gas film must be kept in an expanded state throughout the monitoring process, which is also part of the stiffness matching. Because the adhesive layer is relatively thin, it cannot support the borehole in the surrounding rock. If the surrounding rock is soft or fractured, the borehole may collapse or deform significantly. The flexible filling medium, determined according to the level of disturbance, can provide appropriate flexible support for the surrounding rock of the borehole. On the one hand, it avoids the borehole from deforming into a non-circular shape due to insufficient support, thus preventing the accurate calculation of disturbance stress. On the other hand, it also prevents excessive support, constraining the actual deformation caused by disturbance stress and ensuring the validity of the monitoring data.

[0066] Specifically, after installing the corresponding device inside the monitoring hole, connect the cable leading out of the device to the data acquisition module, and start collecting monitoring data after the colloid solidifies.

[0067] By selecting the stable data after the colloid solidifies as the zero-point data, and using the difference between the monitored strain value and the zero-point data, and by using the full temperature compensation technique to eliminate the temperature effect of the strain, combined with the mechanical parameters of the rock, the disturbance stress of the rock can be obtained.

[0068] Among them, temperature pre-compensation is achieved by measuring the strain value of the rock with the strain gauge attached at different temperatures to obtain the strain of the rock per unit temperature. In addition, the temperature change value during the monitoring process can be measured by the temperature resistance, and finally the influence of temperature on the strain of the surrounding rock can be eliminated.

[0069] As described above, this invention provides a rock mass disturbance stress monitoring device and method with stiffness matching characteristics. It employs a flexible gas film filled with a flexible medium to provide support for borehole drilling in the surrounding rock. By selecting different flexible media for different disturbance levels, it ensures that the borehole does not undergo large deformations. By using different curing adhesives, the stiffness of the adhesive shell in the measuring section of the device is adjustable. This avoids measurement errors caused by excessive adhesive stiffness constraining local deformation of the surrounding rock, while also preventing a decrease in strain transfer efficiency due to insufficient stiffness. The aforementioned stiffness-matched device design and method ensure that rock mass disturbance stress can be effectively transmitted to the monitoring element. The device uses a concave, high-temperature resistant flexible gas film structure. By filling with a flexible medium, the flexible gas film expands and is extruded, thereby adhering the strain gauge to the surface of the surrounding rock. Furthermore, the device provided by this invention incorporates a temperature pre-compensation mechanism to effectively eliminate measurement errors caused by temperature changes, achieving long-term stable monitoring of disturbance stress.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rock mass disturbance stress monitoring device with stiffness matching characteristics, characterized in that, include: Strain gauge rose, strain gauge frame, flexible air film, temperature sensor, and data acquisition module; among which, The flexible gas film is fixed inside the strain gauge frame in a concave shape, and after the flexible gas film is filled with a flexible medium and expands, it is squeezed out to the outside of the strain gauge frame. The strain gauge is attached to the flexible air film on its reverse side, and the temperature sensor is attached to the flexible air film near the strain gauge. The surface of the flexible air film is coated with an adhesive material, which is determined according to the elastic modulus of the rock mass to be tested. The data acquisition module is electrically connected to the strain gauge and the temperature sensor.

2. The rock mass disturbance stress monitoring device with stiffness matching characteristics according to claim 1, characterized in that, The ratio of the elastic modulus of the cured adhesive material to the elastic modulus of the rock mass to be tested is 1 / 20 to 1 / 10.

3. The rock mass disturbance stress monitoring device with stiffness matching characteristics according to claim 1, characterized in that, The adhesive materials include epoxy resin adhesive, flexible modified epoxy adhesive, and polyurethane adhesive; When the elastic modulus of the rock mass to be tested is greater than a preset threshold, the adhesive material is the epoxy resin adhesive. When the elastic modulus of the rock mass to be tested is less than or equal to the preset threshold, the adhesive material is the flexible modified epoxy adhesive or the polyurethane adhesive.

4. The rock mass disturbance stress monitoring device with stiffness matching characteristics according to claim 1, characterized in that, The strain flowers are multiple, and the multiple strain flowers are distributed at equal intervals along the circumference in the middle of the flexible air film; Each strain flower comprises multiple strain gauges at different angles.

5. The rock mass disturbance stress monitoring device with stiffness matching characteristics according to claim 1, characterized in that, One end of the strain gauge frame is equipped with a positioning bolt and a suspension pin; wherein... The dropper is used to determine the rotation angle of the strain gauge frame; The positioning bolt is used to adjust the installation direction of the rock mass disturbance stress monitoring device with stiffness matching characteristics.

6. The rock mass disturbance stress monitoring device with stiffness matching characteristics according to claim 1, characterized in that, The strain gauge frame is provided with a glue storage chamber, which stores the adhesive material.

7. The rock mass disturbance stress monitoring device with stiffness matching characteristics according to claim 1, characterized in that, A valve is installed at the filling port of the flexible air membrane; The flexible medium filling the flexible air film includes water or air.

8. The rock mass disturbance stress monitoring device with stiffness matching characteristics according to claim 1, characterized in that, Multiple lead holes are evenly spaced along the circumference on the outer wall of the strain gauge frame, and a wire corresponding to the strain flower passes through each lead hole.

9. A monitoring method for a rock mass disturbance stress monitoring device with stiffness matching characteristics as described in any one of claims 1-8, characterized in that, The method includes: Drill holes at the monitoring points on the rock mass to be tested and extract the core samples from the holes; The strain gauge was attached to the core sample of the borehole at the installation point of the device, and the core sample was placed in a constant temperature chamber for temperature calibration to obtain temperature compensation data. The elastic modulus of the drill core was measured, and the bonding material was determined based on the elastic modulus. The adhesive material is filled into the glue storage chamber of the strain gauge frame, and the rock mass disturbance stress monitoring device with stiffness matching characteristics is sent to the device installation point via the installation rod; the adhesive material is coated on the surface of the flexible air film by rotating the rock mass disturbance stress monitoring device with stiffness matching characteristics. Rotate the mounting rod according to the state of the needle to ensure that the installation angle of the rock mass disturbance stress monitoring device with stiffness matching characteristics is consistent with the preset installation angle, and fill the flexible air film with a flexible medium so that the flexible air film expands and squeezes out to fit tightly against the borehole inner wall of the monitoring point. After the adhesive material solidifies, monitoring data is collected. The flexible air film support structure filled with flexible medium is maintained throughout the monitoring process, and the monitoring data is corrected based on the temperature compensation data to obtain the disturbance stress of the rock mass to be tested. The monitoring data includes temperature data and stress data.

10. The method according to claim 9, characterized in that, The adhesive materials include epoxy resin adhesive, flexible modified epoxy adhesive, and polyurethane adhesive; Determining the adhesive material based on the elastic modulus includes: When the elastic modulus is greater than a preset threshold, the adhesive material is determined to be the epoxy resin adhesive. When the elastic modulus is less than or equal to the preset threshold, the adhesive material is determined to be the flexible modified epoxy adhesive or the polyurethane adhesive.

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