Method for monitoring vertical deformation of vertical shaft wall of vertical shaft through cooperation of overall and local parts

Abstract

The invention discloses a method for monitoring vertical deformation of a shaft wall of a vertical shaft in a manner that the whole body cooperates with the local body, and the method comprises the following steps: S1, forming a vertical microgroove along the full depth of the shaft wall, arranging a plurality of sensing optical fibers at equal intervals in the circumferential direction, and arranging monitoring points at equal intervals on each sensing optical fiber; s2, embedding the sensing optical fiber in the microgroove by using a filling material; s3, automatically collecting data of the sensing optical fiber by using a cabinet type densely distributed demodulator; s4, introducing a high-precision laser ranging system to carry out cooperative monitoring, and forming a plurality of detection groups in combination with sensing optical fibers; and S5, performing segmentation coefficient correction on the original monitoring data of the sensing optical fiber by using the deformation quantity measured by each monitoring group, thereby obtaining a real well wall full-depth strain field. According to the invention, high-precision, near-continuous and high-cost-performance well wall vertical strain monitoring can be realized, and a potential fracture area can be accurately positioned.

Description

Technical Field

[0001] This invention belongs to the field of wellbore deformation monitoring technology, specifically relating to a method for monitoring vertical deformation of a vertical wellbore that integrates overall coordination with local conditions. Background Technology

[0002] There are currently a considerable number of deep overburden shafts in operation. In these shafts, the additional forces exerted by the strata on the shaft walls, and other stratum loads, are continuously increasing, leading to a constant increase in vertical strain on the shaft walls. This results in a significant risk of rupture, even multiple ruptures. Due to the complex variations in the surrounding strata along the shaft depth, coupled with increased construction activities near mines in recent years, the location of water loss in the surrounding strata is uncertain, leading to diverse locations of shaft wall ruptures. Therefore, to reasonably assess the risk of shaft wall rupture, it is necessary to accurately determine the vertical strain values ​​and distribution of the shaft walls. This is of significant guiding importance for assessing the safety status of the shaft, preventing internal wall ruptures, and developing remedial measures.

[0003] Based on the characteristics of the measured wellbore deformation information, existing deformation monitoring technologies are mainly divided into two categories: overall and local. Overall technologies include traditional large displacement gauges and newer laser ranging technologies. The latter, in particular, can achieve millimeter-level ranging accuracy over distances of several hundred meters, making it very suitable for measuring the overall vertical deformation of the wellbore. However, it cannot obtain the wellbore deformation at different depths. Local technologies can be further divided into two categories: single-point sensors and near-continuous distributed strain optical fibers. Single-point sensors are typically buried in a few selected key layers. Their advantages include tight coupling between the sensor and the wellbore, good stability, and accurate and reliable measurement data. However, these sensors are difficult to deploy in large numbers, resulting in sparse measurement points and an inability to obtain complete vertical strain information of the wellbore, making it difficult to comprehensively reflect the full-depth deformation state of the wellbore structure. Near-continuous distributed strain optical fibers can be deployed in two ways. One is to fix them to the inner surface of the well wall. The main advantage of this method is that it is easy to construct, but the disadvantage is that surface fixation is easily affected by environmental factors such as moisture, temperature changes and hoisting vibration in the well. Unavoidable minor loosening may cause significant errors in deformation measurement results. The other method is to embed them inside the concrete of the well wall. However, it is still necessary to overcome technical difficulties such as minimizing the adverse effects of trenching on the well wall structure and ensuring the grouting quality of the micro vertical long trenches. Summary of the Invention

[0004] The purpose of this invention is to provide a method for monitoring vertical deformation of a vertical shaft wall in a coordinated manner, which can achieve high-precision, near-continuous, and cost-effective monitoring of vertical strain of the shaft wall and can accurately locate potential fracture areas.

[0005] To achieve the above objectives, the present invention provides a method for monitoring vertical deformation of a vertical shaft wall with overall coordination and local integration, comprising the following steps: S1. Vertical microgrooves are opened along the entire depth of the well wall, and several sensing optical fibers are laid out circumferentially at equal intervals. Monitoring points are laid out on each sensing optical fiber at equal intervals. S2. Using filling material, the sensing optical fiber is embedded in the microgroove; S3. Data acquisition of sensing optical fibers is automated using a cabinet-type dense distributed demodulator. S4. Introduce a high-precision laser ranging system for collaborative monitoring. The deployment methods for the high-precision laser ranging system include: At the starting monitoring point at the top of the sensing fiber, a laser reflection target is set up according to the number of sensing fibers. At the corresponding end monitoring point at the bottom of the sensing fiber, a laser rangefinder is set up to ensure that each laser path is consistent with the sensing fiber path, forming multiple monitoring groups composed of sensing fibers and laser rangefinders. S5. Using the deformation measured by each monitoring group, the original monitoring data of the sensing fiber is corrected by segmented coefficients to obtain the true full-depth strain field of the well wall.

[0006] As a further aspect of the present invention: the microgroove opening step includes: 1) Marking the inner wall: Use marking tools to draw markings along the vertical path of the well wall; 2) Grooving: Use a concrete cutting tool to create microgrooves along the marked path, ensuring that the sensing optical fiber is completely submerged in the microgroove; 3) Cleaning: After cutting, use hot air, a brush, and a cloth to remove dust and moisture from the groove; 4) Coating: After mixing the epoxy resin component and the curing agent at a ratio of 1:0.25, apply a thin coating to the inner surface of the micro-groove to form a good bonding surface between the filling material and the original well wall concrete.

[0007] As a further aspect of the present invention: the depth of the microgroove is 10-30mm, the opening diameter of the microgroove is 4-10mm, and the bottom of the microgroove is 2-3mm larger than the opening diameter of the microgroove.

[0008] As a further aspect of the present invention: the sensing optical fiber is arranged vertically, and a V-shaped spring sheet is used to keep the optical fiber vertical and attached to the bottom of the microgroove.

[0009] As a further aspect of the present invention: the filling material is modified epoxy mortar. If the depth of the micro-groove is greater than 10mm, the filling material is filled in layers, each layer not exceeding 10mm. After each layer is filled, it is compacted to ensure that the layer is completely dense and free of air bubbles before the next layer is filled.

[0010] As a further aspect of the present invention: after the filling material has fully solidified, the correction coefficient of the first monitoring group is calculated based on the data obtained from the sensing fiber and laser rangefinder monitoring at equal time intervals in the first monitoring group; the correction coefficient is then substituted into the original data to obtain the corrected true strain value of each monitoring point in the first monitoring group; similarly, the corrected accurate strain values ​​of all monitoring points in the other monitoring groups are obtained; and the true full-depth strain field of the wellbore is constructed using the conventional Kriging interpolation method.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: The high-precision laser ranging technology, which can obtain overall wellbore deformation information, is combined with dense distributed fiber optic deformation sensing technology, which can obtain local wellbore deformation data. The quantitative relationship between the two is used to obtain an accurate vertical strain field of the full depth of the wellbore based on a numerical correction algorithm. It fully integrates the advantages of laser ranging in obtaining high-precision overall deformation data and the advantages of dense optical fiber in obtaining nearly continuous local vertical strain along the well wall depth, overcoming the shortcomings of traditional laser ranging in obtaining local deformation information of the well wall and the lack of accuracy of strain measurement by relying solely on optical fiber. By deploying vertical optical fibers along the entire depth of the well wall and arranging a circumferential monitoring array at equal intervals, combined with laser ranging technology and correction algorithms, high-precision, near-continuous, and cost-effective vertical strain monitoring of the well wall can be achieved, and potential fracture areas can be accurately located. The minimally invasive grooving and embedding process enables near-non-destructive construction, ensuring the structural integrity of the well wall. Furthermore, the use of rapid-setting, early-strength, and micro-expansion filling materials ensures excellent mechanical synergistic deformation capabilities between the optical fiber and the well wall concrete, as well as the long-term operational stability of the monitoring system. This provides reliable and comprehensive technical support for the full life-cycle safety monitoring of vertical wells in deep topsoil. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the fiber optic sensing area for thick topsoil vertical shafts according to the present invention. Figure 2 This is a schematic diagram of the sensor fiber arrangement of the present invention; Figure 3 This is a top view of the microgroove of the present invention. Detailed Implementation

[0013] The invention will now be further described with reference to the accompanying drawings.

[0014] A method for monitoring vertical deformation of a vertical shaft wall with overall coordination and local integration includes the following steps: S1. Thick-surfaced soil vertical shafts are subject to ground loads, including horizontal ground pressure and additional vertical ground pressure, due to their interaction with the surrounding strata. To comprehensively monitor shaft wall strain, vertical microgrooves are drilled along the entire depth of the shaft wall, and several sensing optical fibers are evenly spaced circumferentially. Monitoring points are evenly spaced on each sensing fiber. Considering deployment cost and data volume, it is recommended to deploy 3-5 sensing optical fibers, with a monitoring point every 2 meters on each sensing fiber; if... Figure 1 As shown, in actual engineering, the shaft will pass through various strata such as water-rich sand layers, clay layers, bedrock sections, etc., and the geological environment is complex. Therefore, the sensing fiber optic cable is deployed in the full depth of the shaft.

[0015] Furthermore, the steps for creating a micro-groove include: 1) Inner wall marking: Draw markings along the vertical path using markers or other marking tools; 2) Grooving: Use a concrete cutting tool to create microgrooves along the marked path, ensuring that the sensing optical fiber is completely submerged in the microgroove; 3) Cleaning: After cutting, use hot air, a brush, and a cloth to remove dust and moisture from the groove; 4) Coating: After mixing the epoxy resin component and the curing agent at a ratio of 1:0.25, apply a thin coating to the inner surface of the micro-groove to form a good bonding surface between the filling material and the original well wall concrete, thereby increasing the adhesion.

[0016] Top view of the micro-groove Figure 3 As shown, preferably, the microgroove depth is 10-30mm, the microgroove opening diameter is 4-10mm, and the bottom of the microgroove is 2-3mm larger than the opening diameter. The sensing fiber needs to be embedded inside the inner wall concrete. To simultaneously control the degree of damage to the wellbore structure to a low level and ensure that the sensing fiber can sense the actual stress on the well wall, the microgroove size parameters are determined based on the sensing fiber diameter, the actual wellbore curvature, and the thickness of the well wall protective layer.

[0017] Furthermore, such as Figure 2 As shown, the sensing optical fiber is arranged vertically, and V-shaped spring sheets are used to keep the fiber vertical and attached to the bottom of the microgroove. The spacing of the spring sheets depends on the engineering requirements, with a preferred spacing range of 0.5~1m. The size of the spring sheets depends on the actual groove width.

[0018] S2. Using filling material, the sensing optical fiber is embedded in the microgroove.

[0019] Considering the verticality of the trench and the dampness of the well wall, ordinary mortar flows downwards and cannot be fixed firmly, resulting in poor adhesion. Therefore, it is necessary to select a filling material with micro-expansion, early strength, and rapid setting properties. Preferably, modified epoxy mortar is used as the filling material, and the compressive strength of the filling material must be similar to that of the base material. If the depth of the micro-groove is greater than 10mm, the filling material should be filled in layers, with each layer not exceeding 10mm. After each layer is filled, it should be compacted to ensure that the layer is completely dense and free of air bubbles before filling the next layer.

[0020] S3. Data acquisition from the sensing fiber optic cable is performed automatically using a cabinet-type dense distributed demodulator. The automatically acquired data can be represented as ( x 0, y 0, z 0), where, x 0 represents the x-coordinate of the data point. y 0 represents the ordinate of the data point. z 0 represents the collected values ​​of the data points. These are organized into a dataset containing the spatial location of each data point and its corresponding strain value.

[0021] S4. In practical engineering applications, the monitoring results of sensing optical fibers are easily affected by construction processes. To overcome the strain measurement errors caused by factors such as coupling processes and bonding quality when relying solely on optical fiber sensing in actual construction, a high-precision laser ranging system is introduced for collaborative monitoring while deploying the sensing optical fibers. This system obtains the overall vertical deformation of the well shaft as a correction constraint for the micro-strain data of the optical fibers. The deployment method of the high-precision laser ranging system includes: Laser reflective targets are deployed at the starting monitoring point at the top of the sensing fiber according to the number of sensing fibers, and laser rangefinders are deployed at the corresponding end monitoring point at the bottom of the sensing fiber to ensure that each laser path is consistent with the sensing fiber path, thus forming multiple monitoring groups composed of sensing fibers and laser rangefinders.

[0022] S5. Using the deformation measured by each monitoring group, the original monitoring data of the sensing fiber is corrected by segmented coefficients to obtain the true full-depth strain field of the well wall.

[0023] Specifically, the deformation measured by each laser rangefinder ( i For the number of monitoring groups, i =1,2,...,n), and piecewise coefficient correction is applied to the original monitoring data of distributed optical fibers affected by process (such as bonding slip, voids, etc.) to obtain the true full-depth strain field of the wellbore. The formula for solving the correction coefficient is as follows: ;

[0024] In the formula: during the solution process, it should be ensured that... To obtain the simultaneous equations and then solve for the correction coefficients; The correction factor is used because calculating the corresponding correction factor for each monitoring point is computationally intensive; therefore, it is used as the correction factor. Each monitoring point is considered as a segment, and the correction coefficient for that segment is then calculated. The correction factor for the first paragraph should be determined based on the actual engineering situation. Value and number of segments , , ; This refers to the strain at various points monitored by the sensing fiber optic cable within this section. k Number each monitoring point within this section. This represents the total number of fiber optic monitoring points. Multiples of; The distance between monitoring points.

[0025] After the filling material has fully solidified, the correction coefficients for the first monitoring group are calculated based on the data obtained from the timed monitoring by the sensing fiber and laser rangefinder in the first monitoring group. The equations are as follows: ;

[0026] In the formula: , These represent the first monitoring group monitoring the data at equal time intervals. The deformation value measured by the laser rangefinder and the strain value measured by the sensing fiber are obtained at this time.

[0027] Substituting the correction coefficients of the first monitoring group into the original data, the corrected true strain values ​​of each monitoring point in the first monitoring group are obtained, as shown in the following formula: ;

[0028] In the formula: This represents the corrected true strain value of each monitoring point in the sensing fiber within this segment.

[0029] The other monitoring groups obtained the corrected accurate strain values ​​for all monitoring points in the same way; and constructed the real full-depth strain field of the wellbore using the conventional Kriging interpolation method.

Claims

1. A method for monitoring vertical deformation of a vertical shaft wall with overall coordination and local integration, characterized in that, Includes the following steps: S1. Vertical microgrooves are opened along the entire depth of the well wall, and several sensing optical fibers are laid out circumferentially at equal intervals. Monitoring points are laid out on each sensing optical fiber at equal intervals. S2. Using filling material, the sensing optical fiber is embedded in the microgroove; S3. Data acquisition of sensing optical fibers is automated using a cabinet-type dense distributed demodulator. S4. Introduce a high-precision laser ranging system for collaborative monitoring. The deployment methods for the high-precision laser ranging system include: At the starting monitoring point at the top of the sensing fiber, a laser reflection target is set up according to the number of sensing fibers. At the corresponding end monitoring point at the bottom of the sensing fiber, a laser rangefinder is set up to ensure that each laser path is consistent with the sensing fiber path, forming multiple monitoring groups composed of sensing fibers and laser rangefinders. S5. Using the deformation measured by each monitoring group, the original monitoring data of the sensing fiber is corrected by segmented coefficients to obtain the true full-depth strain field of the well wall.

2. The method for monitoring vertical deformation of a vertical shaft wall with overall coordination and local conditions as described in claim 1, characterized in that, The steps for setting up a micro-slot include: 1) Marking the inner wall: Use marking tools to draw markings along the vertical path of the well wall; 2) Grooving: Use a concrete cutting tool to create microgrooves along the marked path, ensuring that the sensing optical fiber is completely submerged in the microgroove; 3) Cleaning: After cutting, use hot air, a brush, and a cloth to remove dust and moisture from the groove; 4) Coating: After mixing the epoxy resin component and the curing agent at a ratio of 1:0.25, apply a thin coating to the inner surface of the micro-groove to form a good bonding surface between the filling material and the original well wall concrete.

3. The method for monitoring vertical deformation of a vertical shaft wall with overall coordination and local conditions as described in claim 2, characterized in that, The depth of the microgroove is 10-30mm, the opening diameter of the microgroove is 4-10mm, and the bottom of the microgroove is 2-3mm larger than the opening diameter of the microgroove.

4. A method for monitoring vertical deformation of a vertical shaft wall with overall coordination and localization according to claim 1 or 2, characterized in that, The sensing optical fiber is arranged vertically, and a V-shaped spring sheet is used to keep the optical fiber vertical and attached to the bottom of the micro-groove.

5. The method for monitoring vertical deformation of a vertical shaft wall with overall coordination and local conditions as described in claim 1, characterized in that, Modified epoxy mortar is used as the filling material. If the depth of the micro-groove is greater than 10mm, the filling material is filled in layers, with each layer not exceeding 10mm. After each layer is filled, it is compacted to ensure that the layer is completely dense and free of air bubbles before filling the next layer.

6. The method for monitoring vertical deformation of a vertical shaft wall with overall coordination and local conditions as described in claim 1, characterized in that, After the filling material has fully solidified, the correction coefficients of the first monitoring group are calculated based on the data obtained from several monitoring sessions conducted at equal time intervals by the sensing fiber and laser rangefinder in the first monitoring group. By substituting these values ​​into the original data, the corrected true strain values ​​of each monitoring point in the first monitoring group are obtained. Similarly, the corrected accurate strain values ​​of all monitoring points in the remaining monitoring groups are obtained. The true full-depth strain field of the wellbore is then constructed using the conventional Kriging interpolation method.

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