A monitoring and filling device and method for the expansion of karst caves around power transmission towers.

Abstract

A monitoring and filling device and method for the expansion of karst cavities around transmission towers is disclosed. The monitoring and filling device includes a control center and multiple pre-embedded devices. These devices are arranged coaxially around the tower foundation and installed within the karst soil. Each pre-embedded device includes multiple pre-embedded components that circumferentially surround the outside of the tower. Each pre-embedded component includes a hollow column, which is installed within the karst soil and filled with calcium oxide powder. A first monitoring device and a second monitoring device are sequentially installed within the hollow column, and a third monitoring device is movably installed within the hollow column. This invention, by employing multiple pre-embedded devices surrounding the outer ring of the tower, allows for monitoring at various locations on the tower. By monitoring friction, the flow of calcium oxide can be determined, allowing for the replenishment of calcium oxide to suppress the expansion of cavities, resulting in a better filling effect. Simultaneously, it allows for real-time monitoring of the expansion of cavities, providing a good monitoring effect.

Description

Technical Field

[0001] This invention relates to the field of power transmission tower monitoring technology, and in particular to a monitoring and filling device and method for the expansion of karst caves around power transmission towers. Background Technology

[0002] In recent years, the construction of power transmission towers has developed rapidly. After the power transmission towers are built, the surrounding karst caves will expand. Due to factors such as the expansion of karst caves, the foundation of the tower will be deformed. If it is not detected and remedied in time, it may even lead to a collapse accident, resulting in serious economic losses. Therefore, it is necessary to monitor karst caves.

[0003] Current methods for monitoring the expansion of karst caves include geological exploration techniques and feature extraction techniques. However, these methods require specialized knowledge and skills, placing high demands on personnel. Data processing and interpretation also require professional expertise, and significant financial and equipment investments are necessary. Furthermore, the assessment results may be affected by various factors, leading to inaccuracies and potentially worsening of the subsequent cave filling effect. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects and problems of poor monitoring and filling effects of karst caves in the prior art, and to provide a monitoring and filling device and method for the expansion of karst caves around power transmission towers with good monitoring and filling effects.

[0005] To achieve the above objectives, the technical solution of the present invention is: a monitoring and filling device for the expansion of karst soil cavities around transmission towers, comprising a control center and multiple pre-embedded devices. The multiple pre-embedded devices are arranged coaxially around the tower foundation, with the tower as the center. All the pre-embedded devices are installed within the karst soil. Each pre-embedded device includes multiple pre-embedded components, which are arranged circumferentially around the outside of the tower. Each pre-embedded component includes a hollow column, a first monitoring device, a second monitoring device, and a third monitoring device. The hollow column is installed within the karst soil and filled with calcium oxide powder. The first and second monitoring devices are sequentially installed on the inner wall of the hollow column, and the third monitoring device is movably installed within the hollow column. All three monitoring devices are connected to the control center.

[0006] The first monitoring device and the second monitoring device are used to detect the frictional force when calcium oxide powder flows inside the hollow column, and transmit the frictional force to the control center.

[0007] The third monitoring device is used to monitor the heat generated after the reaction of calcium oxide powder with water to determine the shape of the soil cavity;

[0008] The control center is used to determine whether the calcium oxide powder is exhausted and the expansion of the soil cavity based on the friction force, and to determine the material to be filled into the soil cavity based on the shape of the soil cavity monitored by the third monitoring device.

[0009] The hollow column has a first mounting hole and a second mounting hole. A first hollow tube is installed in the first mounting hole, and a second hollow tube is installed in the second mounting hole. The third monitoring device is movably connected to the first hollow tube. The first monitoring device and the second monitoring device are respectively installed on the inner side wall of the second hollow tube. The calcium oxide powder is filled in the second hollow tube. Multiple steel bars are connected to the outer circumference of the hollow column, and the multiple steel bars are all set in the karst soil.

[0010] The third monitoring device includes a telescopic rod and an infrared thermal imaging camera. The telescopic rod is arranged inside the first hollow tube, and the infrared thermal imaging camera is installed at the bottom of the telescopic rod.

[0011] The first monitoring device includes a first friction sensor, and the second monitoring device includes a second friction sensor. The first friction sensor is installed in the middle of the inner wall of the second hollow tube, and the second friction sensor is installed at the bottom of the inner wall of the second hollow tube.

[0012] A method for monitoring and filling karst caves expanding around power transmission towers, the method being applied to a monitoring and filling device for karst cave expansion around power transmission towers, the method comprising the following steps:

[0013] Step 1: Select the pole to be monitored and detect the soil holes under the pole. Determine the location of multiple pre-embedded devices based on the location and size of the soil holes.

[0014] Step 2: At the determined location, dig a pit according to the depth of each pre-embedded component, and put multiple pre-embedded components in each pre-embedded device into the prepared pit along the circumferential direction with the tower as the center.

[0015] Step 3: Install the first monitoring device, the second monitoring device, and the third monitoring device inside the hollow column, and fill the hollow column with calcium oxide powder so that the calcium oxide powder comes into contact with the karst soil.

[0016] Step 4: Monitor the friction between calcium oxide powder and hollow column using the first and second monitoring devices. The control center generates a friction curve based on the acquired friction data and determines whether the calcium oxide powder is exhausted and the expansion of the soil cavity.

[0017] Step 5: The control center fills the soil cavity based on whether the calcium oxide powder is exhausted and the expansion of the soil cavity, combined with the shape of the soil cavity monitored by the third monitoring device.

[0018] The number of embedded devices is four, and the four embedded devices are arranged in a staggered ring around the tower. The specific steps for determining the positions of multiple embedded devices in step one are as follows:

[0019] Numerical simulation using finite element method (FEM) software was performed to obtain the expansion critical line function f of the soil cavity. Based on the expansion critical line function f, the positions of four pre-embedded devices were determined by dividing the cavity into multiple equal parts. The horizontal distances of the four pre-embedded devices from the tower foundation are L0, L2, L3, and L1, respectively, and the depths of the four pre-embedded devices are H0, H2, H3, and H1, respectively. The calculation formulas are as follows:

[0020] f = αr0 + βL + λH;

[0021]

[0022]

[0023] Among them, c, Let F and N represent the cohesion and internal friction angle of the soil layer, respectively; F and N represent the tensile and compressive loads on the tower, respectively; r0 represent the radius of the soil cavity; H represent the vertical distance from the top of the soil cavity to the ground surface; L represent the horizontal distance from the top of the soil cavity to the center of the bottom of the tower foundation; L0 represent the horizontal distance from the pre-embedded device to the tower foundation when the soil cavity is directly below the tower foundation; H0 represent the depth of the pre-embedded device when the soil cavity is directly below the tower foundation; H1 represent the depth of the pre-embedded device located at the arch point of the soil cavity expansion line; and L1 represent the horizontal distance from the pre-embedded device located at the arch point of the soil cavity expansion line to the tower foundation.

[0024] Step four, generating the friction force curve, includes:

[0025] The first and second monitoring devices collect data on the frictional force changes at two different locations—the middle and bottom—of the hollow column, respectively, and transmit the data to the control center via wireless signal at a frequency of once per second. The control center then uses the data to create two visualized variation curves, forming a frictional force curve graph.

[0026] Step four, which involves determining whether the calcium oxide powder has been depleted and the extent of the expansion of the cavities, includes:

[0027] The control center will collect the friction force change data and calculate the slope change of each group in 10-second intervals.

[0028] When the slope of the first and second curves changes with small fluctuations or remains unchanged, it is within the allowable error range. At this time, the soil cavity does not expand and the calcium oxide powder is not exhausted.

[0029] When the slope of the first curve changes from a small fluctuation or no change at first, then increases rapidly, and then decreases slowly to a certain value, the trend of the second curve is the same as that of the first curve. At this time, the soil hole has expanded to the bottom of the hollow column and the calcium oxide powder is about to be exhausted.

[0030] When the slope of the first curve changes from a small fluctuation or no change at first, then increases rapidly, then drops sharply and remains unchanged for a long time; the second curve changes in the same way as the first curve, at which point the soil cavity has expanded to the bottom of the hollow column and the calcium oxide powder has been exhausted.

[0031] Step five involves filling the soil cavity, including:

[0032] When the soil cavity expands to the bottom of the hollow column and the calcium oxide powder is about to be exhausted, fill the hollow column with calcium oxide powder until the calcium oxide powder is flush with the top surface of the hollow column.

[0033] When the soil cavity expands to the bottom of the hollow column and the calcium oxide powder is exhausted, the corresponding hollow column is located, water is injected into the hollow column, and at the same time, the heat inside the soil cavity is detected and the shape of the soil cavity is determined by the third monitoring device. Based on the shape of the soil cavity, the control center determines that the filling material of the soil cavity is a silicate material. Then, an injection pipe is inserted into the hollow column, and the silicate material flows into the soil cavity through the injection pipe. At this time, the calcium oxide powder and water in the soil cavity react chemically to generate a large amount of calcium hydroxide, which reacts with the added silicate material to generate calcium silicate gel to fill the soil cavity.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. In the monitoring and filling device and method for the expansion of karst cavities around transmission towers of the present invention, multiple pre-embedded devices are used, which surround the outer ring of the tower, to monitor various locations on the tower. By monitoring the frictional force, the flow of calcium oxide can be determined, thereby replenishing calcium oxide to inhibit the expansion of the cavities. Simultaneously, the expansion of the cavities can be monitored in real time. Since the reaction of calcium oxide with water is exothermic, the shape of the cavities can be determined by monitoring the heat. Simultaneously, the generated calcium hydroxide reacts with oxygen in the cavities to produce calcium carbonate, which fills the cavities. When the cavities expand too much to be filled by calcium oxide, the shape of the cavities is determined by the heat generated during the reaction, and a suitable filling and solidification material is selected based on the shape of the cavities, resulting in a good filling effect. Therefore, the present invention has good monitoring and filling effects.

[0036] 2. In the monitoring and filling device and method for the expansion of karst cavities around transmission towers of the present invention, changes in frictional force data detected by a friction sensor can quickly determine whether the karst cavities have expanded to the vicinity of the tower and the material consumption within the hollow column. By connecting the two sides of the hollow column to steel bars inserted into the soil, the monitoring effect is avoided due to the settlement of the hollow column. The shape of the cavities is accurately drawn using the heat generated by the reaction of an infrared thermal imaging camera and calcium oxide powder with water in the cavities. Silicate materials are then used to further react with the generated calcium hydroxide to fill the cavities. The exothermic reaction between the calcium oxide powder and water accelerates the formation of a gel-like substance, thus filling the cavities at a low cost. Therefore, the present invention is low in cost, has good monitoring effect, and provides good filling effect.

[0037] 3. In the monitoring device and method for the expansion of karst cavities around transmission towers of the present invention, the use of finite element software to simulate the initial cavity expansion critical line to determine the installation position of the pre-embedded device makes the monitoring more accurate and reliable. Simultaneously, combining the cavity expansion critical line to determine the position of each pre-embedded device leads to better subsequent cavity filling effect. By using two friction force curves, the flow of calcium oxide powder can be determined, thereby judging the cavity expansion situation. This allows for corresponding filling operations based on specific cavity expansion conditions. Therefore, the present invention is convenient to operate and has high monitoring accuracy. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of a monitoring device for the expansion of karst caves around power transmission towers, as described in this invention.

[0039] Figure 2 This is a schematic diagram of the structure of the pole and karst cave in this invention.

[0040] Figure 3 This is a structural schematic diagram of the tower and pre-embedded components in this invention.

[0041] Figure 4 This is a schematic diagram of the pre-embedded component in this invention.

[0042] Figure 5 This is a schematic diagram of the hollow column, the first hollow tube, and the second hollow tube in this invention.

[0043] In the diagram: 1. Pole tower; 2. Embedded device; 21. Embedded component; 21. Hollow column; 211. First mounting hole; 212. Second mounting hole; 213. First hollow tube; 214. Second hollow tube; 215. Reinforcing bar; 216. First monitoring device; 3. First friction sensor; 31. Second monitoring device; 4. Second friction sensor; 41. Third monitoring device; 5. Telescopic pole; 51. Infrared thermal imaging camera; 52. Control center; 6. Calcium oxide powder; 7. Soil hole; 8. Expansion critical line; 9. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] Example 1:

[0046] See Figures 1 to 5 A monitoring and filling device for the expansion of karst caves around a power transmission tower includes a control center 6 and multiple pre-embedded devices 2. The multiple pre-embedded devices 2 are arranged coaxially around the tower foundation 1 on the outside of the tower. The multiple pre-embedded devices 2 are installed in the karst soil. Each pre-embedded device 2 includes multiple pre-embedded components 21, which are arranged circumferentially around the outside of the tower. Each pre-embedded component 21 includes a hollow column 211, a first monitoring device 3, a second monitoring device 4, and a third monitoring device 5. The hollow column 211 is installed in the karst soil and filled with calcium oxide powder 7. The first monitoring device 3 and the second monitoring device 4 are installed sequentially on the inner wall of the hollow column 211. The third monitoring device 5 is movably installed inside the hollow column 211. The first monitoring device 3, the second monitoring device 4, and the third monitoring device 5 are all connected to the control center 6.

[0047] The first monitoring device 3 and the second monitoring device 4 are used to detect the frictional force of calcium oxide powder 7 flowing inside the hollow column 211, and transmit the frictional force to the control center 6.

[0048] The third monitoring device 5 is used to monitor the heat generated after the calcium oxide powder 7 reacts with water to determine the shape of the soil hole 8;

[0049] The control center 6 is used to determine whether the calcium oxide powder 7 is exhausted and the expansion of the soil hole 8 based on the friction force, and to determine the material to be filled into the soil hole 8 in combination with the shape of the soil hole 8 monitored by the third monitoring device 5.

[0050] The hollow column 211 has a first mounting hole 212 and a second mounting hole 213. A first hollow tube 214 is installed in the first mounting hole 212, and a second hollow tube 215 is installed in the second mounting hole 213. The third monitoring device 5 is movably connected to the first hollow tube 214. The first monitoring device 3 and the second monitoring device 4 are respectively installed on the inner sidewall of the second hollow tube 215. The calcium oxide powder 7 is filled in the second hollow tube 215. A plurality of steel bars 216 are connected to the outer circumferential surface of the hollow column 211, and the plurality of steel bars 216 are all set in the karst soil.

[0051] The third monitoring device 5 includes a telescopic rod 51 and an infrared thermal imaging camera 52. The telescopic rod 51 is arranged inside the first hollow tube 214, and the infrared thermal imaging camera 52 is installed at the bottom of the telescopic rod 51.

[0052] The first monitoring device 3 includes a first friction sensor 31, and the second monitoring device 4 includes a second friction sensor 41. The first friction sensor 31 is installed in the middle of the inner wall of the second hollow tube 215, and the second friction sensor 41 is installed at the bottom of the inner wall of the second hollow tube 215.

[0053] In this embodiment, the hollow column 211, the first hollow tube 214, and the second hollow tube 215 are made of high-friction and corrosion-resistant steel, with their tops slightly higher than the ground. The upper ends of the first hollow tube 214 and the second hollow tube 215 are detachably sealed, while the lower ends are not sealed. The reinforcing bar 216 is made of high-friction and corrosion-resistant steel. When the third monitoring device 5 is required to monitor, first use a flashlight to observe whether the bottom of the pre-embedded hollow column 211 is connected to the soil hole 8. If it can be directly inserted into the infrared thermal imaging camera 52, no treatment is required. If there is no connection or the bottom is covered with soil, construction personnel need to use steel pipes to penetrate the soil through the fittings to ensure that the infrared thermal imaging camera 52 can smoothly penetrate into the soil hole 8 for detection.

[0054] Example 2:

[0055] See Figure 2 A monitoring and filling method for the expansion of karst caves around transmission towers, wherein the monitoring and filling method is applied to the monitoring device for the expansion of karst caves around transmission towers in Example 1, and the monitoring and filling method includes the following steps:

[0056] Step 1: Select the tower to be monitored and detect the soil hole 8 under the tower. Determine the location of multiple pre-embedded devices 2 based on the location and size of the soil hole 8.

[0057] Step 2: At the determined location, dig a pit according to the depth of each pre-embedded component 21, and put multiple pre-embedded components 21 in each pre-embedded device 2 into the prepared pit along the circumferential direction with the tower as the center.

[0058] Step 3: Install the first monitoring device 3, the second monitoring device 4, and the third monitoring device 5 inside the hollow column 211, and fill the hollow column 211 with calcium oxide powder 7 so that the calcium oxide powder 7 comes into contact with the karst soil.

[0059] Step 4: The frictional force between calcium oxide powder 7 and hollow column 211 is monitored by the first monitoring device 3 and the second monitoring device 4. The control center 6 generates a frictional force curve based on the acquired frictional force data and determines whether the calcium oxide powder 7 is exhausted and the expansion of the soil hole 8.

[0060] Step 5: Based on whether the calcium oxide powder 7 is exhausted and the expansion of the soil cavity 8, combined with the shape of the soil cavity 8 monitored by the third monitoring device 5, the control center 6 fills the soil cavity 8.

[0061] The number of the pre-embedded devices 2 is four, and the four pre-embedded devices 2 are arranged in a staggered ring around the tower. The specific steps for determining the positions of the multiple pre-embedded devices 2 in step one are as follows:

[0062] Numerical simulation using finite element method (FEM) software was performed to obtain the expansion critical line function f of the soil hole 8. Based on the expansion critical line function f, the positions of the four pre-embedded devices 2 were determined by dividing the structure into multiple equal parts. The horizontal distances of the four pre-embedded devices 2 from the tower foundation 1 are L0, L2, L3, and L1, respectively, and the depths of the four pre-embedded devices 2 are H0, H2, H3, and H1, respectively. The calculation formulas are as follows:

[0063] f = αr0 + βL + λH;

[0064]

[0065] Among them, c, Let F and N represent the cohesion and internal friction angle of the soil layer, respectively; F and N represent the tensile and compressive loads on the tower, respectively; r0 represent the radius of the soil hole 8; H represent the vertical distance from the top of the soil hole 8 to the ground surface; L represent the horizontal distance from the top of the soil hole 8 to the center of the bottom of the tower foundation 1; L0 represent the horizontal distance from the pre-embedded device 2 to the tower foundation 1 when the soil hole 8 is directly below the tower foundation 1; H0 represent the depth of the pre-embedded device 2 when the soil hole 8 is directly below the tower foundation 1; H1 represent the depth of the pre-embedded device 2 located at the arch point of the soil hole expansion line 9; and L1 represent the horizontal distance from the pre-embedded device 2 located at the arch point of the soil hole expansion line 9 to the tower foundation 1.

[0066] In this embodiment, in order to facilitate construction and not affect the normal operation and monitoring effect of the tower foundation, when the soil hole 8 appears directly below the tower foundation 1, the pre-embedded component 21 is selected to be closely attached to the tower foundation 1 and pre-embedded.

[0067] Example 3:

[0068] The basic content is the same as Example 2, except that:

[0069] Step four, generating the friction force curve, includes:

[0070] The first monitoring device 3 and the second monitoring device 4 respectively collect friction force change data at two different positions, the middle and the bottom of the calcium oxide powder 7 and the hollow column 211, and transmit the data to the control center 6 via wireless signal at a frequency of once per second. The control center 6 forms two visualized variation curves to create a friction force curve graph.

[0071] Step four, which involves determining whether the calcium oxide powder 7 is exhausted and the expansion of the soil cavity 8, includes:

[0072] Control Center 6 will collect the friction force change data and calculate the slope change of each group in 10-second intervals;

[0073] When the slope of the first curve and the second curve changes with small fluctuations or remains unchanged, it is within the allowable error range. At this time, the soil hole 8 does not expand and the calcium oxide powder 7 is not exhausted.

[0074] When the slope of the first curve changes from a small fluctuation or no change at first, then increases rapidly, and then slowly decreases to 0, the trend of the second curve is the same as that of the first curve. At this time, the soil hole 8 has expanded to the bottom of the hollow column 211 and the calcium oxide powder 7 is about to be exhausted.

[0075] When the slope of the first curve changes, it first fluctuates slightly or remains unchanged, then increases rapidly, then drops sharply to 0, and remains unchanged for a long time; the trend of the second curve is the same as that of the first curve. At this time, the soil hole 8 has expanded to the bottom of the hollow column 211 and the calcium oxide powder 7 has been exhausted.

[0076] In this embodiment, when the slopes of adjacent sets of data in the two curves differ by more than double, the control center 6 will issue an early warning notification. Staff need to pay close attention to the curve change trend of the early warning group to determine whether the calcium oxide powder 7 is exhausted and make corresponding preparations. If the first curve shows small fluctuations within 30 minutes after decreasing, it indicates that the calcium oxide powder 7 has not been consumed by more than half. If the first curve drops sharply to 0 when decreasing and there is no change within 30 minutes, it indicates that the calcium oxide powder 7 has been consumed by more than half.

[0077] Example 4:

[0078] The basic content is the same as Example 3, except that:

[0079] Step five involves filling the soil cavity 8, including:

[0080] When the soil hole 8 expands to the bottom of the hollow column 211 and the calcium oxide powder 7 is about to be exhausted, fill the hollow column 211 with calcium oxide powder 7 until the calcium oxide powder 7 is flush with the upper surface of the hollow column 211.

[0081] When the soil cavity 8 expands to the bottom of the hollow column 211 and the calcium oxide powder 7 is exhausted, the corresponding hollow column 211 is located, and water is injected into the hollow column 211. At the same time, the heat inside the soil cavity 8 is detected by the third monitoring device 5 and the shape of the soil cavity 8 is determined. The control center 6 determines that the filling material of the soil cavity 8 is a silicate material based on the shape of the soil cavity 8. Then, an injection pipe is inserted into the hollow column 211, and the silicate material flows into the soil cavity 8 through the injection pipe. At this time, the calcium oxide powder 7 and water in the soil cavity 8 react chemically to generate a large amount of calcium hydroxide, which reacts with the added silicate material to generate calcium silicate gel to fill the soil cavity 8.

[0082] In this embodiment, the silicate material can be industrial by-products such as fly ash and slag powder. When fly ash and slag powder flow into the soil cave 8, the calcium oxide powder 7 in the soil cave 8 reacts with water to generate a large amount of calcium hydroxide, which reacts with the active silica-alumina components of fly ash and slag powder to generate calcium silicate-calcium aluminate gel (CSH). At this time, the temperature in the soil cave 8 is relatively high, and the calcium silicate-calcium aluminate gel (CSH) has high strength and low permeability, resulting in a good filling effect.

Claims

1. A monitoring and filling device for the expansion of karst caves around power transmission towers, characterized in that: The system includes a control center (6) and multiple pre-embedded devices (2). The multiple pre-embedded devices (2) are arranged coaxially around the tower foundation (1) on the outside of the tower. The multiple pre-embedded devices (2) are installed in the karst soil. The pre-embedded device (2) includes multiple pre-embedded components (21). The multiple pre-embedded components (21) are arranged around the outside of the tower in a circular direction. The pre-embedded component (21) includes a hollow column (211), a first monitoring device (3), a second monitoring device (4), and a third monitoring device (5). The hollow column (211) is installed in the karst soil and filled with calcium oxide powder (7). The first monitoring device (3) and the second monitoring device (4) are installed on the inner side wall of the hollow column (211) in sequence. The third monitoring device (5) is movably installed in the hollow column (211). The first monitoring device (3), the second monitoring device (4), and the third monitoring device (5) are all connected to the control center (6). The first monitoring device (3) and the second monitoring device (4) are used to detect the friction force of the calcium oxide powder (7) flowing in the hollow column (211) respectively, and transmit the friction force to the control center (6); The third monitoring device (5) is used to monitor the heat generated after the calcium oxide powder (7) reacts with water to determine the shape of the soil hole (8); The control center (6) is used to calculate the slope change of each group of collected friction force change data in 10s groups. When the slope change trend of the first curve and the second curve is small fluctuation or no change, it is within the allowable error range. At this time, the soil hole (8) does not expand and the calcium oxide powder (7) is not exhausted. When the slope change trend of the first curve is small fluctuation or no change, then a rapid increase, and then a slow decrease to 0, the change trend of the second curve is the same as that of the first curve. At this time, the soil hole (8) has expanded to the bottom of the hollow column (211) and the calcium oxide powder (7) is about to be exhausted. When the slope change trend of the first curve is small fluctuation or no change, then a rapid increase, and then a sudden drop to 0, and no change for a long time, the change trend of the second curve is the same as that of the first curve. At this time, the soil hole (8) has expanded to the bottom of the hollow column (211) and the calcium oxide powder (7) has been exhausted. Combined with the shape of the soil hole (8) monitored by the third monitoring device (5), the material to be filled in the soil hole (8) is determined.

2. The monitoring and filling device for the expansion of karst caves around transmission towers according to claim 1, characterized in that: The hollow column (211) has a first mounting hole (212) and a second mounting hole (213). A first hollow tube (214) is installed in the first mounting hole (212), and a second hollow tube (215) is installed in the second mounting hole (213). The third monitoring device (5) is movably connected to the first hollow tube (214). The first monitoring device (3) and the second monitoring device (4) are respectively installed on the inner sidewall of the second hollow tube (215). The calcium oxide powder (7) is filled in the second hollow tube (215). A plurality of steel bars (216) are connected to the outer circumference of the hollow column (211). The plurality of steel bars (216) are all set in the karst soil.

3. The monitoring and filling device for the expansion of karst caves around transmission towers according to claim 2, characterized in that: The third monitoring device (5) includes a telescopic rod (51) and an infrared thermal imaging camera (52). The telescopic rod (51) is arranged inside the first hollow tube (214), and the infrared thermal imaging camera (52) is installed at the bottom of the telescopic rod (51).

4. The monitoring and filling device for the expansion of karst caves around transmission towers according to claim 2, characterized in that: The first monitoring device (3) includes a first friction sensor (31), and the second monitoring device (4) includes a second friction sensor (41). The first friction sensor (31) is installed in the middle of the inner wall of the second hollow tube (215), and the second friction sensor (41) is installed at the bottom of the inner wall of the second hollow tube (215).

5. A method for monitoring and filling the expansion of karst caves around transmission towers, characterized in that: The monitoring and filling method is applied to the monitoring and filling device for the expansion of karst caves around transmission towers as described in claim 1. The monitoring and filling method includes the following steps: Step 1: Select the tower to be monitored and detect the soil hole (8) under the tower. Determine the location of multiple pre-embedded devices (2) based on the location and size of the soil hole (8). Step 2: At the determined location, dig a pit according to the depth of each pre-embedded component (21), and put multiple pre-embedded components (21) in each pre-embedded device (2) into the prepared pit along the circumferential direction with the tower as the center; Step 3: Install the first monitoring device (3), the second monitoring device (4), and the third monitoring device (5) inside the hollow column (211), and fill the hollow column (211) with calcium oxide powder (7) so that the calcium oxide powder (7) comes into contact with the karst soil. Step 4: The frictional force between calcium oxide powder (7) and hollow column (211) is monitored by the first monitoring device (3) and the second monitoring device (4). The control center (6) generates a frictional force curve based on the acquired frictional force data and determines whether the calcium oxide powder (7) is exhausted and the expansion of the soil hole (8). Step 5: The control center (6) fills the soil hole (8) according to whether the calcium oxide powder (7) is exhausted and the expansion of the soil hole (8), combined with the shape of the soil hole (8) monitored by the third monitoring device (5).

6. The method for monitoring and filling the expansion of karst caves around transmission towers according to claim 5, characterized in that: The number of the pre-embedded devices (2) is four, and the four pre-embedded devices (2) are arranged in a staggered ring around the tower. The specific steps for determining the positions of the multiple pre-embedded devices (2) in step one are as follows: Numerical simulation was performed using finite element simulation software to obtain the expansion critical line function of the soil cavity (8). According to the expansion critical line function The positions of the four pre-embedded devices (2) are determined by dividing the structure into multiple equal parts. The horizontal distances of the four pre-embedded devices (2) from the tower foundation (1) are as follows: , , , The depths of the four pre-embedded devices (2) are respectively , , , The calculation formula is as follows: ； ； ； ； ； ； ； ； ； ； in, , The cohesion and internal friction angle of the soil layer. , For the tower subjected to tension and compression loads, The radius of the earthen cave (8) is The vertical distance from the top of the earthen cave (8) to the ground surface. The horizontal distance from the top of the earthen hole (8) to the center of the bottom of the tower foundation (1) is... The horizontal distance from the pre-embedded device (2) to the tower foundation (1) when the earth hole (8) appears directly below the tower foundation (1) is given. The depth of the pre-embedded device (2) when the soil hole (8) appears directly below the tower foundation (1), The depth of the pre-embedded device (2) located at the arch point of the earth cave expansion line (9), The horizontal distance from the pre-embedded device (2) located at the arch point of the earth tunnel expansion line (9) to the tower foundation (1).

7. A method for monitoring and filling the expansion of karst caves around transmission towers according to claim 5, characterized in that: Step four, generating the friction force curve, includes: The first monitoring device (3) and the second monitoring device (4) collect friction force change data at two different locations, the middle and the bottom of the calcium oxide powder (7) and the hollow column (211), respectively, and transmit the data to the control center (6) via wireless signal at a frequency of once per second. The control center (6) forms two visualized variation curves to form a friction force curve graph.

8. A method for monitoring and filling the expansion of karst caves around transmission towers according to claim 5, characterized in that: The filling process for the soil cavity (8) in step five includes: When the soil cavity (8) expands to the bottom of the hollow column (211) and the calcium oxide powder (7) is about to be exhausted, fill the hollow column (211) with calcium oxide powder (7) until the calcium oxide powder (7) is flush with the upper surface of the hollow column (211); When the soil cavity (8) expands to the bottom of the hollow column (211) and the calcium oxide powder (7) is exhausted, the corresponding hollow column (211) is found, water is injected into the hollow column (211), and at the same time, the heat inside the soil cavity (8) is detected by the third monitoring device (5) and the shape of the soil cavity (8) is determined. The control center (6) determines that the filling material of the soil cavity (8) is a silicate material according to the shape of the soil cavity (8). Then, an injection pipe is inserted into the hollow column (211) and the silicate material flows into the soil cavity (8) through the injection pipe. At this time, the calcium oxide powder (7) in the soil cavity (8) reacts with water to generate a large amount of calcium hydroxide, which reacts with the added silicate material to generate calcium silicate gel to fill the soil cavity (8).

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