Wall surface deformation high-precision acquisition method, sensor and calibration equipment

Abstract

The invention provides a wall surface deformation high-precision acquisition method, a sensor and calibration equipment. The method comprises the following steps: calibrating the sensor; the calibrated sensor is installed on a super-long horizontal survey drill hole wall surface strain capture test short section; acquiring hole wall photos and hole diameter shapes of the drill holes at different depths; based on the hole wall picture and the hole diameter shape, selecting at least three test points which are in different directions and have no structural surfaces and no drill marks at a specified depth; pushing the wall surface strain capture test short section of the ultra-long horizontal survey drill hole to the depth of the test point; the sensor is pressed to the position of the test point; and releasing the rock core of the test point, and continuously collecting hole wall strain change data through the sensor in the process. The system has the functions of resisting high temperature and high pressure and collecting high-precision strain and temperature change of a wall surface, a strain correction method is provided, and the precision of collected data is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and in particular to a high-precision acquisition method, a sensor, and a calibration device for wall deformation of an ultra-long horizontal exploration borehole. Background Art

[0002] High geostress areas are a complex geological condition often encountered during tunnel construction. High geostress refers to the stress experienced by underground rock formations at depth, which often has a significant impact on tunnel construction and operation. The presence of high geostress areas is crucial for tunnel construction, primarily in the following ways: First, they impact tunnel stability. Rocks in high geostress areas are subject to significant geostress, making them susceptible to deformation and damage. This deformation and damage directly impact tunnel stability and can even lead to serious accidents such as tunnel collapse. Therefore, the impact of high geostress must be fully considered during tunnel construction, and appropriate engineering measures must be implemented to ensure tunnel stability. Second, they trigger geological hazards. High geostress areas carry a high risk of geological hazards. For example, high geostress can trigger rockbursts in hard and brittle rock, while in soft rock, it can cause significant deformation of the cavern. These hazards not only impact tunnel construction progress and quality but also pose a threat to the safety of construction personnel and equipment. Therefore, when constructing tunnels in high geostress areas, it is crucial to strengthen geological hazard prevention and control efforts.

[0003] The stress relief method is one of two in-situ geostress testing methods recommended by the International Rock Mechanics Testing Technical Committee. The stress relief method is based on the relationship between the stress at the borehole wall and the geostress in a three-dimensional cylindrical borehole. The geostress is calculated by measuring the strain at the borehole wall and the rock mass deformation parameters. Key to ensuring the accuracy of in-situ geostress testing is the ability to accurately measure borehole wall deformation and temperature changes during drilling, overcome the complex high-temperature and high-pressure testing environment of deep boreholes, and prevent sensor damage caused by rough borehole walls due to drilling.

[0004] Ultra-long horizontal exploration hole technology combines horizontal directional drilling and ultra-long-distance drilling. Horizontal directional drilling utilizes a directional drill rod and a guide drill bit to drill a specific distance in a specific direction, achieving directional extension of the borehole. Ultra-long-distance drilling, on the other hand, utilizes specially designed drilling tools and processes to achieve long-distance borehole extension. The combination of these two technologies enables ultra-long horizontal exploration holes to accurately survey geological conditions over long distances, greatly improving exploration accuracy and efficiency. The technical advantages of ultra-long horizontal exploration holes are primarily reflected in the following aspects: (1) Long-distance, high-precision detection: Through advanced navigation systems and mechanical equipment, ultra-long horizontal exploration holes can achieve long-distance, high-precision geological drilling, providing detailed geological data for tunnel design and construction.

[0005] (2) Comprehensive disclosure of geological information: This technology can reveal a variety of information such as geological structure, rock and soil properties, and groundwater conditions, providing a comprehensive and accurate geological basis for tunnel engineering.

[0006] (3) Early warning of geological disasters: By analyzing the collected geological data, the ultra-long horizontal exploration hole can be used to predict the tunnel construction surface.

[0007] (4) Predict the geological conditions ahead, promptly identify and resolve potential geological disaster risks, and ensure construction safety.

[0008] Currently, the in-situ geostress testing methods and equipment within the ultra-long horizontal exploration borehole technology system are still immature. This is primarily due to the fact that ultra-long horizontal exploration boreholes are drilled using a small drill bit to create a large borehole, resulting in an uneven wall surface. This places higher demands on the protection and testing accuracy of the wall strain acquisition sensors. Furthermore, since the drilling fluid in some sections of the horizontal borehole does not completely fill the entire borehole, the test is affected by the heat generated by the drill bit during rock breaking, resulting in low test accuracy. Furthermore, during geostress testing in ultra-long horizontal exploration boreholes, the sensor must be pushed against the borehole wall for acquisition. Therefore, the strain generated by the pushing pressure must be eliminated to ultimately obtain accurate wall strain. Summary of the Invention

[0009] In view of the defects in the prior art, the purpose of the present invention is to provide a high-precision acquisition method, sensor and calibration equipment for the wall deformation of an ultra-long horizontal exploration borehole.

[0010] According to one aspect of the present invention, a method for high-precision acquisition of wall deformation of an ultra-long horizontal exploration borehole is provided, comprising: Calibrate the push-type sensor using calibration equipment to confirm its linearity and hysteresis, calibrate the conversion coefficient between the sensor and direct measurement of the strain gauge, and calibrate the conversion coefficient between the push-type and adhesive measurement methods; Mounting the sensor on a test subsection for capturing wall strain; Acquire images of the hole wall and hole diameter shape at different depths of the drill hole; Based on the hole wall and hole diameter shape images, at least three test points with no structured surface and no drill marks in different directions are selected at a specified depth; Pushing the test sub to the depth of the test point; Pressing the sensor to the test point; The test sub is used to drill a core and release the stress at the test point. During this process, the sensor continuously collects the strain change data of the hole wall, and the final measurement value is obtained by calibrating the conversion coefficient.

[0011] Preferably, the calibrating the push-type sensor to confirm the linearity and hysteresis of the sensor includes: Place the sensor into the calibration device; Manipulating the calibration device to press the sensor; After each press, the calibration device is controlled to load and unload the sensor; collecting data points of strain changes during the loading and unloading process; Based on the data points of the strain change, the loading and unloading linearity and the loading and unloading hysteresis of the sensor are evaluated, and the maximum number of tests of the sensor is determined.

[0012] Preferably, based on the data points of the strain change, the loading and unloading linearity of the sensor is evaluated, specifically: The least square method is used to fit the data points of the loading and unloading process, and the loading and unloading curve fitting formula and the corresponding R square value are obtained; The R-squared value is judged. If the R-squared value is less than the lowest value of the threshold range, the linearity level is determined to be poor; if the R-squared value is greater than the highest value of the threshold range, the linearity level is determined to be excellent; if the R-squared value is between the threshold range, the linearity level is determined to be good.

[0013] Preferably, the degree of loading and unloading hysteresis is evaluated based on the data points of the strain change, specifically: The least square method is used to fit the data points of the loading and unloading process respectively, and the loading and unloading curve fitting formula is obtained to obtain the loading and unloading curves; The hysteresis degree of the sensor is quantitatively evaluated based on the calculation of the loading and unloading curves. The hysteresis degree includes an energy method quantitative evaluation coefficient and an elastic-plastic quantitative evaluation coefficient. The energy method quantitative evaluation coefficient is the ratio of the area enclosed by the loading curve and the x-axis to the area enclosed by the unloading curve and the x-axis; the elastic-plastic quantitative evaluation coefficient is the ratio of the strain value before loading to the strain value after unloading.

[0014] Preferably, determining the maximum number of tests of the sensor includes: During the calibration process, each time the sensor is pressed, loading and unloading is performed; The loading and unloading linearity and loading and unloading hysteresis of each loading and unloading are calculated; when any one of the loading and unloading linearity and the loading and unloading hysteresis exceeds a feasible threshold range, it indicates that the maximum number of test times of the sensor has been reached.

[0015] Preferably, the calibration of the conversion coefficient between the sensor and the direct measurement of the strain gauge includes: The conversion coefficient between the sensor and the direct measurement of the strain gauge is obtained based on the actual load applied by the calibration device during the loading and unloading process and the data points of the strain change collected.

[0016] Preferably, the conversion coefficient between the calibration press-type measurement method and the adhesive-type measurement method includes: In the calibration equipment, a sensing sheet is pasted on the same material and a sensor is fixed; Simultaneously applying the same pressing force to the sensing sheet and the sensor, and drawing a sensor fit calibration curve under different pressing force conditions, wherein the abscissa of the curve is the pressing force and the ordinate is the collected strain value; Based on the two fit degree calibration curves, a conversion coefficient between the calibrated press-type measurement method and the adhesive-type measurement method is obtained.

[0017] Preferably, the continuously collecting the hole wall strain change data by the sensor and obtaining the final measurement value by calibrating the conversion coefficient include: Obtaining the measured strain value and pressing force collected by the sensor; True strain value = (measured strain value - pressing force × b) × a, where a is the conversion coefficient between direct measurement by the sensor and the strain gauge, and b is the conversion coefficient between the pressing measurement method and the adhesive measurement method. The pressing force is calculated based on the spring displacement inside the sensor.

[0018] According to a second aspect of the present invention, a pressure sensor is provided for use in any one of the above-mentioned methods for high-precision acquisition of wall deformation, comprising: A protective shell, the front end of which is used to contact the wall, and the front end is made of an elastic membrane; a sensing sheet, located in the protective shell and fixed to the elastic membrane; a sheath connected to the rear end of the protective shell; A communication cable is passed through the sheath and connected to the sensor piece using a watertight joint; a spring, coaxial with the sheath and embedded in the sheath; A displacement sensor is arranged in the sheath and collects the displacement of the spring.

[0019] According to a third aspect of the present invention, a calibration device is provided for use in any one of the above-mentioned methods for high-precision acquisition of wall deformation, comprising: The container is a closed space used to place the sensor; a strain collector, located outside the container and connected to the sensor via a cable; a pressurized joint, located at the top of the container and communicating with the interior of the container; a pressurizer, located outside the container and connected to the pressurizing joint; A hydraulic digital display, located on the pressurizer; The still water preparation device is located on the top of the container and is communicated with the interior of the container.

[0020] Compared with the prior art, the embodiments of the present invention have at least one of the following beneficial effects: The high-precision acquisition method for wall deformation of ultra-long horizontal exploration boreholes in the embodiment of the present invention evaluates the linearity, hysteresis and deformation resistance of the sensor, which can significantly improve the test accuracy and stability of the high-precision wall deformation sensor.

[0021] The high-precision wall deformation acquisition method for ultra-long horizontal exploration boreholes in the embodiment of the present invention can carry out multiple tests at different depths in deep boreholes. Compared with traditional deep hole strain acquisition methods, it is more efficient and has a higher test success rate.

[0022] The high-precision acquisition method for wall deformation of ultra-long horizontal exploration boreholes in the embodiment of the present invention provides a strain correction method to improve measurement accuracy.

[0023] The press-type sensor in the embodiment of the present invention can avoid damage from the unevenness and sharp corners on the wall of the irregular drilled hole, has high temperature resistance, high pressure resistance and waterproof functions, and can carry out experiments repeatedly in the complex environment of deep drilling.

[0024] The push-type sensor in the embodiment of the present invention can be quickly replaced, is easy to operate, has low cost and high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings: Figure 1 This is a flow chart of a high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole in one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a sensor in a preferred embodiment of the present invention. In the figure, 11-communication cable, 12-metal sheath, 13-metal protective shell, 14-watertight joint, 15-thread, 16-sensor cable, 17-glue, 18-sensor; Figure 3 This is a schematic diagram of a sensor indoor calibration device in a preferred embodiment of the present invention. In the figure, 1-sensor, 2-base, 3-strain collector, 4-cable, 5-pressure container, 6-airless water preparation device, 7-pipeline, 8-hydraulic digital display, 9-handle, 10-pressurizer, 101-pressurization connector; Figure 4 A pressure fitting diagram for evaluating the loading and unloading linearity of a sensor in a preferred embodiment of the present invention; Figure 5 This is a diagram for evaluating the hysteresis degree during the loading and unloading process of a calibration experiment in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0027] In one embodiment of the present invention, Figure 1 As shown, a high-precision method for collecting wall deformation of an ultra-long horizontal exploration borehole is provided, comprising: S100, uses calibration equipment to calibrate the push-type sensor to confirm its linearity and hysteresis, calibrate the conversion coefficient between the sensor and direct measurement of strain gauges, and calibrate the conversion coefficient between push-type and adhesive measurement methods; S200, install the sensor on the test sub for capturing wall strain; S300, acquiring images of the hole wall and hole diameter shape at different depths of the drill hole; S400, based on the hole wall and hole diameter shape images, selecting at least three test points in different directions at a specified depth that have no structured surface and no drill marks; S500: Push the test sub to the depth of the test point; S600, press the sensor to the test point; The S700 uses a test sub to drill core and relieve stress at the test point. During this process, sensors continuously collect data on the strain changes in the hole wall, and the final measurement value is obtained through the conversion coefficient obtained by calibration.

[0028] In the process of ultra-long horizontal exploration drilling, ultra-long horizontal exploration drilling is usually used. Therefore, in this embodiment, the ultra-long horizontal exploration drilling can be used to bind the camera equipment to obtain the image of the borehole. The test pup joint is a tool with integrated sensors and sampling devices, which is usually installed in the drill string or continuous oil pipe and enters the horizontal well section while drilling. The ultra-long horizontal exploration drilling can be used to send the test pup joint to the designated test point. The test pup joint ensures that the sensor is protected during the sinking process, avoids damage to the sensor, and provides it with power supply and data acquisition functions. In addition, the side wall hollow diamond drill rig that comes with the test pup joint can relieve stress and drill cores.

[0029] The above embodiment evaluates the linearity, hysteresis and deformation resistance of the sensor, which can significantly improve the test accuracy and stability of the high-precision wall deformation sensor.

[0030] Because the use of a press-type sensor changes the existing measurement method of directly attaching the sensor sheet to the wall, the linearity, hysteresis characteristics, and strain value of the measurement are affected to varying degrees. Therefore, the press-type sensor needs to be calibrated. In a preferred embodiment, the sensor is calibrated using a calibration device in step S100 to confirm its linearity and hysteresis. Specifically, the following steps can be used: S101, placing the sensor into an indoor calibration device; S102, operating the calibrated device to press the sensor; S103, after each press, controlling the calibration device to load and unload the sensor; S104, collecting data points of strain changes during loading and unloading; S105 , based on the data points of strain change, evaluate the loading and unloading linearity and loading and unloading hysteresis of the sensor, and determine its durability and maximum number of tests.

[0031] If the relationship between strain and pressure during loading and unloading of a strain sensor is highly linear, it indicates that the sensor is stable and the conversion between strain and pressure is relatively simple. In a preferred embodiment, the loading and unloading linearity of the sensor is evaluated using the following method: S105.1, based on the collected induced strain data points, the loading and unloading curves of the equipment are obtained as shown in the figure.

[0032] S105.2, use the least squares method to fit the data points of the loading and unloading process respectively, and obtain the loading and unloading curve fitting formula and the corresponding R square value.

[0033] S105.3, if the R-squared value is less than 0.90, the linearity is considered poor; if the R-squared value is greater than 0.95, the linearity is considered excellent; if the R-squared value is between 0.90 and 0.95, the linearity is considered good.

[0034] In some specific embodiments, Figure 4 As shown in Figure 2, a schematic diagram of the linearity judgment of the loading and unloading process of the calibration experiment (the asterisk represents the unloading process; the red dotted line is the linear fitting line of the unloading process, in this case its R square value is 0.998, and the linearity is excellent; the square represents the loading process; the solid line is the loading process; the black solid line is the linear fitting line of the loading process, in this case its R square value is 0.91, and the linearity is average).

[0035] Hysteresis, also known as hysteresis or delay, refers to the situation where the response (such as strain) of a material lags behind the change in the driving force (such as stress) in time when the material is subjected to external force and undergoes loading and unloading processes, resulting in the loading and unloading curves not coinciding, forming a closed hysteresis loop, such as Figure 5 As shown in the figure (this figure is a hysteresis degree evaluation diagram for the loading and unloading process of the calibration experiment, where: A loading - the area of ​​the oblique stripes in the figure; A unloading - the area of ​​the gray part in the figure; P loading - the corresponding strain value before loading; P unloading - the corresponding strain value after unloading). The area of ​​this hysteresis loop represents the energy dissipated by the material during the loading and unloading process, that is, the hysteresis energy or dissipated energy. For high-precision strain sensors, a large hysteresis effect means that the test stability of the equipment is poor. Therefore, in the process of calibrating the sensor, the occurrence of the hysteresis effect should be avoided as much as possible. Therefore, in a preferred embodiment of the present invention, two indicators are used to evaluate the hysteresis degree of the sensor, specifically: First, the smaller the area of ​​the hysteresis loop, the smaller the loading and unloading dissipation energy, the closer the loading and unloading curves are, the less significant the hysteresis effect is, and the better the stability of the sensor. Therefore, the following indicators are used to quantitatively evaluate the hysteresis degree of the sensor: ; Where: S1 is the quantitative evaluation coefficient of the sensor hysteresis degree energy method, A 加载 It refers to the area enclosed by the loading curve and the x-axis in the stress-strain curve. 卸载 This refers to the area between the unloading curve and the x-axis in the stress-strain curve. S1 ranges from 0 to 1. The closer it is to 1, the closer the loading and unloading curves are, the less significant the hysteresis effect is, and the better the sensor performance.

[0036] Secondly, another major characteristic of hysteresis is that after unloading, the material cannot fully return to its original state, but rather has a certain amount of residual deformation. This residual deformation is caused by plastic deformation or irreversible deformation of the material during the loading process. To ensure that the sensor has good test accuracy and stability, the strain values ​​before and after loading and unloading need to be kept as consistent as possible. Based on this, the following formula is used to quantitatively evaluate the linearity of the sensor: ; Where: S2 is the elastic-plastic quantitative evaluation coefficient of the sensor hysteresis degree, P 加载 It refers to the strain value before loading in the stress-strain curve, P 卸载 This refers to the strain value after unloading in the stress-strain curve. S2 ranges from 0 to 1. The closer it is to 1, the closer the loading and unloading curves are, the less significant the hysteresis effect is, and the better the sensor performance.

[0037] The sensor needs to be tested multiple times underground at different depths and test points. It is important to ensure that the sensor exhibits minimal or no plastic deformation after repeated compressions, maintains good linearity, and prevents further hysteresis. To evaluate the sensor's deformation resistance, the sensor undergoes multiple compression tests, and after each compression, the probe is loaded and unloaded. By assessing its hysteresis and linearity, its durability and maximum number of tests can be determined.

[0038] The above embodiment can maintain the test work in the borehole within the maximum number of tests without returning to the ground for reinstallation, thus ensuring the work efficiency. However, during the sidewall stress relief operation, due to the large amount of heat generated by the drill bit breaking the rock, the strain gauge is affected by temperature stress and high temperature drift, and its test accuracy is greatly reduced, resulting in a large test error, which leads to abnormal final ground stress solution results and failure of the ground stress test. Therefore, it is necessary to require the strain acquisition device to be able to obtain the temperature changes during the test process, so as to perform temperature correction on the results. Specifically, in an environment of 0~150 degrees Celsius, the strain value change caused by the temperature rise of the sensor is tested every 10°C, so as to draw a curve of the sensor's temperature change for subsequent temperature calibration. According to the temperature change during the stress relief process obtained by the sensor, the strain change caused by temperature is obtained through the temperature calibration curve, and this part of the strain change is removed from the measured value.

[0039] In addition, since the measurement is performed by pressing the sensor against the surface of the drilled hole wall, the degree of contact between the sensor and the object being measured will affect the strain measurement results, thereby interfering with the measured hole wall strain value. Therefore, in actual testing, the strain generated by pressing must be corrected. In a preferred embodiment, step S100 is implemented to calibrate the conversion coefficient between the pressing and adhesive measurement methods. Specifically, the following method can be used: S106, conducting calibration tests of the adhesive strain measurement method and the press strain measurement method, that is, pasting a sensor and fixing a sensor on the same material in the calibration equipment.

[0040] Adhesive bonding involves gluing the sensor to the surface of the object being measured, causing it to deform along with the object. In some cases, where gluing the sensor is not possible, pressure is applied from the rear of the sensor to press it firmly against the surface, causing both to deform. Here, "fixing" the sensor simply means pressing it against the surface of the object being measured.

[0041] At step S107, the same pressing force is applied to both sensors simultaneously, and a calibration curve for sensor fit is plotted under different pressing force conditions. This calibration curve measures the sensitivity (linearity or hysteresis) of the sensors to external loading and unloading forces, as measured by applying different pressing forces to the sensors. The abscissa of the curve represents the pressing force, and the ordinate represents the collected strain value. Generally, pressure is applied from the rear side of the sensor.

[0042] S108: Based on the two fit degree calibration curves, a conversion coefficient b between the calibrated press-type measurement method and the adhesive-type measurement method is obtained.

[0043] Of course, the measurement data obtained by using sensors and direct measurement using strain gauges will also be different. Therefore, it is necessary to obtain the conversion coefficient a between the sensor and direct measurement using strain gauges based on the actual load applied by the calibration equipment during the loading and unloading process and the data points of the collected strain changes.

[0044] Furthermore, in a preferred embodiment, in step S700, a test sub is used to drill a core and relieve stress at the test point. During this process, a sensor is used to continuously collect data on the strain change of the hole wall, and a final measurement value is obtained by calibrating the conversion coefficient. The following steps can be used: S701, obtaining the measured strain value and pressing force collected by the sensor; S702, true strain value = (measured strain value - pressing force × b) × a, where a is the conversion coefficient between direct measurement by the sensor and the strain gauge, and b is the conversion coefficient between the pressing measurement method and the adhesive measurement method. The pressing force is calculated based on the spring displacement inside the sensor.

[0045] Specifically, the displacement Dt of the spring at any time t during the stress release process of the sensor attached to the side wall can be obtained through the displacement sensor, and the pressing force at any time t can be obtained by combining the spring stiffness k.

[0046] The above embodiment takes into account the conversion coefficient between the strain gauge and the sensor, and the conversion coefficient between the adhesive and press-type measurement methods. It can restore the strain data obtained by the existing press-type sensor test to the data of the standard adhesive strain gauge, thereby improving the measurement accuracy.

[0047] At present, the BWSRM ground stress test equipment uses waterproof strain gauges to directly obtain micro-deformation of the wall surface. Due to the simple protection measures, it is easy to be damaged after measuring a few test points, so it must be recovered and reinstalled on the ground. The replacement process is relatively cumbersome and requires the entire equipment to be disassembled before it can be implemented, which seriously affects the work efficiency. Therefore, based on the same inventive concept, one embodiment of the present invention provides a press-type sensor, specifically, Figure 2As shown, a metal protective shell 13 is used. The front end of the shell is designed to contact the wall, and the rear end is threaded and connected to the metal sheath 12 via threads 15. A sensor 18 is installed within the metal protective shell 13. This sensor 18 is adhered to the center of the metal protective shell 13 with glue 17. The sensor cable 16 is integrated with a watertight connector 14, enabling quick insertion. A communication cable 11 is passed through the rear metal sheath. One end of this cable is connected to the sensor 18 via a watertight connector 14, and the other end is connected to an external data collector, enabling real-time data collection from the sensor. A spring is installed within the rear metal sheath to measure applied pressure. The sensor designed in the aforementioned embodiment is capable of protecting the strain gauge from corrosive drilling fluid, rock cuttings, and sharp protrusions on the irregular borehole wall. This design achieves waterproofing, ensuring the smooth operation of the strain gauge. Furthermore, the sensor exhibits high-temperature resistance and offers the advantages of quick insertion, ease of installation, and multiple reuse.

[0048] In some specific embodiments, the sensing piece may be a KFGS-3-350-D17-11 L3M3S waterproof strain gauge rosette produced by Kyowa Electronics Co., Ltd. of Japan.

[0049] The push-type sensor in this embodiment of the present invention is immune to damage from irregularities and sharp corners on the walls of drilled holes. It is resistant to high temperatures, high pressures, and water, and can be repeatedly tested in the complex environments of deep drilled holes. It is quick to replace, easy to operate, low-cost, and has high measurement accuracy.

[0050] Based on the same inventive concept, another embodiment of the present invention provides a special indoor calibration device tailored to the characteristics of the sensor. Figure 3 As shown, the indoor calibration equipment consists of a pressurizer 10, a pressure-resistant container 5, an airless water preparation device, a pipeline 7, a pressure joint 101, etc. The pressure-resistant container 5 is a closed space for placing the sensor 1, which is placed on the base 2; the strain collector 3 is located outside the pressure-resistant container 1 and is connected to the sensor 1 by a cable; the pressure joint 101 is located at the top of the pressure-resistant container 5 and is connected to the interior of the container; the pressurizer 10 is located outside the pressure-resistant container 5 and is connected to the pressurization joint 101; the hydraulic digital display 8 is located on the pressurizer 10; the airless water preparation device 6 is located at the top of the pressure-resistant container 5 and is connected to the interior of the container. Among them, the pressurizer 10 is connected to the pressure-resistant container 5 through the pipeline 7 and the pressure joint 101, and the pressure-resistant container is pressurized by pressing the handle 9 downward; the airless water preparation device 6 is connected to the external water source through the pipeline 7, and is used to generate bubble-free water to fill the entire pressure-resistant container. After the sensor designed in the above embodiment is placed in the pressure-resistant container 5, it is connected to the strain collector 3 through a line to collect strain changes during loading and unloading.

[0051] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various modifications or variations within the scope of the claims without affecting the essence of the present invention. The above preferred features may be used in any combination as long as they do not conflict with each other.

Claims

1. A high-precision method for collecting wall deformation of an ultra-long horizontal exploration borehole, characterized in that: include: Calibrate the push-type sensor using calibration equipment to confirm its linearity and hysteresis, calibrate the conversion coefficient between the sensor and direct measurement of the strain gauge, and calibrate the conversion coefficient between the push-type and adhesive measurement methods; Mounting the sensor on a test subsection for capturing wall strain; Acquire images of the hole wall and hole diameter shape at different depths of the drill hole; Based on the hole wall and hole diameter shape images, at least three test points with no structured surface and no drill marks in different directions are selected at a specified depth; Pushing the test sub to the depth of the test point; Pressing the sensor to the test point; The test sub is used to drill a core and release the stress at the test point. During this process, the sensor continuously collects the strain change data of the hole wall, and the final measurement value is obtained by calibrating the conversion coefficient.

2. The high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole according to claim 1 is characterized in that: The calibrating of the push-type sensor to confirm the linearity and hysteresis of the sensor includes: placing the sensor into a calibration device; Manipulating the calibration device to press the sensor; After each press, the calibration device is controlled to load and unload the sensor; collecting data points of strain changes during the loading and unloading process; Based on the data points of the strain change, the loading and unloading linearity and the loading and unloading hysteresis of the sensor are evaluated, and the maximum number of tests of the sensor is determined.

3. The high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole according to claim 2, characterized in that: Based on the data points of the strain change, the loading and unloading linearity of the sensor is evaluated, specifically: The least square method is used to fit the data points of the loading and unloading process, and the loading and unloading curve fitting formula and the corresponding R square value are obtained; The R-squared value is judged, and if the R-squared value is less than the lowest value of the threshold range, the linearity level is judged to be poor; If the R-squared value is greater than the highest value of the threshold range, the linearity level is judged to be excellent; if the R-squared value is between the threshold range, the linearity level is judged to be good.

4. The high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole according to claim 2, characterized in that: Based on the data points of the strain change, the degree of loading and unloading hysteresis is evaluated, specifically: The least square method is used to fit the data points of the loading and unloading process respectively, and the loading and unloading curve fitting formula is obtained to obtain the loading and unloading curves; Calculating a quantitative evaluation of the hysteresis degree of the sensor based on the loading and unloading curves, the hysteresis degree includes an energy method quantitative evaluation coefficient and an elastic-plastic quantitative evaluation coefficient, the energy method quantitative evaluation coefficient being the ratio of the area enclosed by the loading curve and the x-axis to the area enclosed by the unloading curve and the x-axis; The elastic-plastic quantitative evaluation coefficient is the ratio of the strain value before loading to the strain value after unloading.

5. The high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole according to claim 2, characterized in that: Determining the maximum number of tests for the sensor includes: During the calibration process, each time the sensor is pressed, loading and unloading is performed; Calculate the loading and unloading linearity and loading and unloading hysteresis for each loading and unloading; When either the loading and unloading linearity or the loading and unloading hysteresis exceeds a feasible threshold range, it indicates that the maximum number of sensor tests has been reached.

6. The high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole according to claim 2, characterized in that: The calibration of the conversion coefficient between the sensor and the direct measurement of the strain gauge includes: The conversion coefficient between the sensor and the direct measurement of the strain gauge is obtained based on the actual load applied by the calibration device during the loading and unloading process and the data points of the strain change collected.

7. The high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole according to claim 2, characterized in that: The conversion coefficient between the two measurement methods of press-type and adhesive-type calibration includes: In the calibration equipment, a sensing sheet is pasted on the same material and a sensor is fixed; Simultaneously applying the same pressing force to the sensing sheet and the sensor, and drawing a sensor fit calibration curve under different pressing force conditions, wherein the abscissa of the curve is the pressing force and the ordinate is the collected strain value; Based on the two fit degree calibration curves, a conversion coefficient between the calibrated press-type measurement method and the adhesive-type measurement method is obtained.

8. The high-precision acquisition method for wall deformation of an ultra-long horizontal exploration borehole according to claim 1 is characterized in that: The sensor is used to continuously collect the hole wall strain change data, and the final measurement value is obtained by calibrating the conversion coefficient, including: Obtaining the measured strain value and pressing force collected by the sensor; True strain value = (measured strain value - pressing force × b) × a, where a is the conversion coefficient between direct measurement by the sensor and the strain gauge, and b is the conversion coefficient between the pressing measurement method and the adhesive measurement method. The pressing force is calculated based on the spring displacement inside the sensor.

9. A pressure sensor, used in the high-precision wall deformation acquisition method according to any one of claims 1 to 8, characterized in that: include: A protective shell, the front end of which is used to contact the wall, and the front end is made of an elastic membrane; a sensing sheet, located in the protective shell and fixed to the elastic membrane; a sheath connected to the rear end of the protective shell; A communication cable is passed through the sheath and connected to the sensor piece using a watertight joint; a spring, coaxial with the sheath and embedded in the sheath; A displacement sensor is arranged in the sheath and collects the displacement of the spring.

10. A calibration device used in the high-precision wall deformation acquisition method according to any one of claims 1 to 8, characterized in that: include: The container is a closed space used to place the sensor; a strain collector, located outside the container and connected to the sensor via a cable; a pressurized joint, located at the top of the container and communicating with the interior of the container; a pressurizer, located outside the container and connected to the pressurizing joint; A hydraulic digital display, located on the pressurizer; The still water preparation device is located on the top of the container and is communicated with the interior of the container.

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