A construction site foundation pit displacement monitoring device

Abstract

The application discloses a construction site foundation pit displacement monitoring device. The construction site foundation pit displacement monitoring device comprises a distance measuring part installed above the ground, a connecting base for providing stable installation support is installed at the lower end of the distance measuring part, a monitoring part for monitoring horizontal displacement changes of deep soil layers is installed at the lower end of the connecting base, and a bottom sealing part is installed at the lower end of the monitoring part. The distance measuring part comprises a vertical rod, a distance measuring instrument is fixedly installed at the upper end of the vertical rod, and the distance measuring instrument can measure the horizontal distance between the vertical rod and a fixed point. The construction site foundation pit displacement monitoring device provided by the application can realize accurate monitoring of the horizontal displacement of deep soil bodies by using only one kind of inexpensive and mature sensor, i.e. a gyroscope, compared with the prior art, without the need of relying on high-precision pressure sensors and complex environmental compensation devices, so that the manufacturing cost of the device is reduced and the reliability of the device is improved.

Description

Technical Field

[0001] This invention relates to the field of foundation pit monitoring technology, and in particular to a foundation pit displacement monitoring device for construction sites. Background Technology

[0002] Foundation pit monitoring refers to the systematic observation and measurement of key parameters such as deformation, internal forces, and water levels of the supporting structure, surrounding soil and rock, and adjacent buildings, underground pipelines, and other environmental objects during foundation pit excavation and underground engineering construction. Its core purpose is to guide construction through data feedback, achieve information-based management, prevent engineering risks, and ensure the safety of the foundation pit itself and its surrounding environment. Monitoring content mainly includes the displacement and internal forces of the supporting structure, deep horizontal displacement of the soil, groundwater level, and settlement and deformation of surrounding buildings. Traditional monitoring relies on instruments such as inclinometers and stress gauges, while modern technology increasingly employs IoT-based automated monitoring systems to achieve real-time data acquisition, transmission, and early warning.

[0003] Existing technology discloses an automated monitoring device for deep displacement in deep foundation pits, publication number CN118880846A. It includes a control box with a water pump installed inside. The input end of the water pump is connected to a pumping pipe, and the output end of the control box is connected to a first probe via a cable. The bottom of the first probe is fixedly connected to a first pair of connecting pipes. The device also includes a water extraction mechanism, comprising a counterweight fixedly connected to the bottom of a second probe; a flushing mechanism; a cleaning mechanism; an anti-deviation mechanism; and a mud scraping mechanism. The advantages are: by using the installed humidity sensor, water pump, and pumping pipe, the water pump can extract and discharge the accumulated water inside the inclinometer tube through a pipeline channel formed by the air inlet pipe, pumping pipe, first water supply pipe, second water supply pipe, branch pipe, and annular groove. This reduces the impact of water pressure on the soil, thereby improving the accuracy and reliability of the monitoring data, and also prevents water accumulation from causing pipe corrosion or damage to the monitoring equipment.

[0004] The existing technologies mentioned above rely on precision sensors to obtain pressure information. At the same time, it is necessary to eliminate the influence of environmental factors such as groundwater on the sensors in order to obtain relatively accurate information about underground soil layers. This makes implementation difficult and manufacturing costs high.

[0005] Therefore, it is necessary to provide a construction site foundation pit displacement monitoring device to solve the above-mentioned technical problems. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the present invention provides a construction site foundation pit displacement monitoring device that uses the calculus method and only utilizes the gyroscope, a cheap and technically mature and reliable sensor, to measure the horizontal displacement of the soil layer.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A construction site foundation pit displacement monitoring device includes: a ranging part installed above ground, a connecting foundation for providing stable installation support installed at the lower end of the ranging part, a monitoring part for monitoring the horizontal displacement change of deep soil layers installed at the lower end of the connecting foundation, and a bottom seal installed at the lower end of the monitoring part; The distance measuring unit includes a pole, and a distance measuring instrument is fixedly installed at the upper end of the pole. The distance measuring instrument can measure the horizontal distance between the pole and a fixed point. The connection foundation is a cylinder buried in the ground. The part of the cylinder above the ground is called the upper cylinder, and the part of the cylinder below the ground is called the lower cylinder. The monitoring unit includes a deformable tube vertically inserted into the soil layer. Multiple marker points are fixedly installed at equal intervals on the side wall of the deformable tube. A measuring trolley is slidably installed inside the deformable tube and moves uniformly from top to bottom. A gyroscope for monitoring the vertical tilt angle of the measuring trolley is installed on the measuring trolley. The measuring trolley is driven by a drive assembly. The gyroscope on the measuring trolley detects the vertical tilt angle once each time the measuring trolley passes a marker point. The bottom sealing includes a bottom box with an opening at the top and a seal at the bottom, and the bottom box is sealed and installed at the bottom of the deformable tube; The upright is detachably connected to the upper cylinder, and the lower cylinder is fixed below ground level by cast-in-place concrete around its perimeter.

[0008] Preferably, the drive assembly includes a transmission belt, with its two ends respectively fitted onto a first fixed pulley and a second fixed pulley. The first fixed pulley is installed inside the lower cylinder, and a stationary shaft is fixedly installed on the side of the lower cylinder. A drive shaft is also installed inside the lower cylinder and rotatably mounted on its side wall. The input end of the drive shaft is fixedly connected to the output end of the motor. The stationary shaft is located directly above the drive shaft. The drive shaft passes through the first fixed pulley and can drive it to rotate. The second fixed pulley is fixedly connected to the first fixed pulley.

[0009] Preferably, the second fixed pulley is installed inside the bottom box, and the bottom box also contains a stationary shaft and a drive shaft. The connection method between the stationary shaft and the drive shaft and the bottom box is the same as the connection method between the lower cylinder and the stationary pulley. The second fixed pulley is installed on the drive shaft, and the drive shaft is located at the upper end of the stationary shaft.

[0010] Preferably, the measuring trolley includes a center plate, on which multiple guide rods are connected and fixedly connected. End plates are fixedly installed at both ends of the guide rods. A slide plate is also installed around the guide rods. A diagonal brace is installed on the slide plate. A wheel hub is rotatably installed at the end of the diagonal brace away from the slide plate. The wheel hub contacts the deformable tube.

[0011] Preferably, the slide plate is slidably mounted on the guide rod, one end of the slide plate is hinged to the support rod, the other end of the support rod is hinged to the middle of the diagonal brace, the end of the diagonal brace away from the wheel hub is hinged to the center plate, a threaded sleeve is fixedly mounted on the slide plate, a lead screw is threadedly mounted on the threaded sleeve, one end of the lead screw is rotatably mounted on the end plate, and the other end is fixedly connected to the output shaft of the first motor. The lead screw pushes the threaded sleeve to slide on the guide rod, thereby adjusting the angle between the diagonal brace and the central axis of the lead screw.

[0012] Preferably, the transmission belt has a closed structure, with one spoke passing through the center plate, slide plate, and end plate of the measuring trolley without contacting them, and the other spoke being fixedly connected to the center plate, slide plate, and end plate.

[0013] Preferably, a second motor is fixedly installed on the diagonal brace, and a bevel gear is fixedly installed on the output end of the second motor. A bevel gear is also fixedly installed on the rotating shaft on the hub. The two bevel gears mesh, and the second motor drives the hub to rotate after starting.

[0014] Preferably, the inner wall of the deformable tube is provided with a slide rail that matches the position of the wheel hub on the measuring trolley. The axial direction of the slide rail is parallel to the axial direction of the deformable tube, and the slide rail guides the measuring trolley to move linearly along the axial direction of the slide rail.

[0015] Preferably, an intermediate plate located in the horizontal direction is fixedly installed between the upper cylinder and the lower cylinder, and the diameter of the intermediate plate is larger than the diameter of the upper cylinder and the lower cylinder.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses only a gyroscope, a cheap and technologically mature sensor, to achieve accurate monitoring of horizontal displacement of deep soil. Compared with the prior art, it does not need to rely on high-precision pressure sensors and complex environmental compensation devices, thus reducing the manufacturing cost of the device and improving the reliability of the device. (2) The present invention divides the bent and deformed tube into several small straight segments by arranging the marking points at equal intervals, and calculates the total displacement by accumulating and summing the points. The measurement principle is simple. (3) The present invention further improves the accuracy and reliability of measurement by setting a distance measuring unit on the ground surface and comparing it with the deep displacement accumulation result, thus achieving dual verification. Attached Figure Description

[0017] Figure 1 A front view schematic diagram of the construction site foundation pit displacement monitoring device provided by the present invention; Figure 2 A schematic diagram of the internal structure of the construction site foundation pit displacement monitoring device provided by the present invention; Figure 3A schematic diagram of the internal structure of the foundation connection part of the construction site foundation pit displacement monitoring device provided by the present invention; Figure 4 This invention provides a schematic diagram of the horizontal displacement calculation principle of the construction site foundation pit displacement monitoring device. Figure 5 A first-view structural schematic diagram of the measuring trolley of the construction site foundation pit displacement monitoring device provided by the present invention; Figure 6 A schematic diagram of the second-view structure of the measuring trolley for the construction site foundation pit displacement monitoring device provided by the present invention; Figure 7 A top view of the measuring trolley of the construction site foundation pit displacement monitoring device provided by the present invention.

[0018] The corresponding names of the reference numerals in the attached drawings are as follows: 10, ranging unit; 11, upright pole; 111, lower pole; 112, base; 12, rangefinder; 13, electrical control box; 20, connecting foundation; 21, upper cylinder; 22, intermediate plate; 23, lower cylinder; 30, monitoring unit; 31, transmission belt; 311, first fixed pulley; 312, second fixed pulley; 313, statically fixed shaft; 314, drive shaft; 32, marking point; 33, measuring trolley; 331, center plate; 332, sliding plate; 333, end plate; 334, guide rod; 335, first motor; 336, second motor; 337, lead screw; 338, threaded sleeve; 339, support rod; 34, deformable tube; 341, slide rail; 35, hub; 351, bevel gear; 352, diagonal brace; 40, bottom sealing; 41, bottom box. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0020] Example 1: like Figure 1 As shown, the construction site foundation pit displacement monitoring device provided by the present invention utilizes the concept of calculus to calculate the horizontal displacement of the deep soil by measuring the inclination changes of equidistant small line segments inside the soil layer. Its overall structure can be divided into an above-ground part and an underground part, specifically including: a ranging part 10 installed above the ground for monitoring the displacement of the ground surface reference point; a connecting foundation 20 buried below the ground for providing stable support; a monitoring part 30 that penetrates deep into the soil layer to sense and monitor the horizontal displacement changes of the deep soil; and a sealing bottom 40 sealed at the bottom of the monitoring part 30.

[0021] Specifically, such as Figure 1As shown, the ranging unit 10 is installed above the ground. Its function is to directly detect the horizontal displacement on the ground. During installation, it is installed in a dot matrix distribution at locations outside the foundation pit where soil displacement is likely to occur. The units are distributed from near to far along the edge of the foundation pit, and a monitoring network is formed between multiple ranging units 10 to record the changes in horizontal displacement between adjacent ranging units 10. When horizontal displacement of the soil occurs, the difference in the distance data between adjacent measuring points near the foundation pit increases, while the difference in the distance data between measuring points far from the foundation pit remains basically unchanged. At this time, the change in horizontal displacement between the farthest measuring point and the measuring point closest to the foundation pit is the horizontal displacement of the soil surface of the foundation pit.

[0022] The ranging unit 10 includes a vertically arranged pole 11 and a rangefinder 12 fixedly installed on the upper end of the pole 11. The bottom of the pole 11 is detachably connected to the upper end of the connecting base 20, which will be described later, so as to facilitate the transportation, installation and subsequent maintenance and replacement of the device.

[0023] The rangefinder 12 is a laser rangefinder. Its measuring end is aligned with a reference point on the previous rangefinder 12 as the observation point, while the first row of devices closest to the foundation pit, that is, the frontmost devices, are aligned with a fixed reference point, such as a reflecting prism installed on a stable rock layer. By measuring the change in the horizontal distance from the rangefinder 12 to the reference point in real time and the data changes of adjacent devices in the monitoring network for verification, the horizontal displacement of the surface monitoring point (i.e., the top of the pole 11) can be accurately obtained.

[0024] In addition, to facilitate electrical control and data acquisition, an electrical control box 13 is fixedly installed in the middle of the pole 11. The electrical control box 13 integrates a controller, battery, data acquisition module and wireless transmission module, which are used to uniformly manage the electronic components such as the measuring trolley 33 and motor mentioned later, and transmit the acquired data to a remote server.

[0025] like Figure 1-3 As shown, the connecting base 20 is the "anchor point" of the entire device in the underground part and the middle part connecting the ground ranging part 10 and the underground monitoring part 30. Its structure is a cylindrical assembly buried at a specific depth below the ground. The cylindrical assembly includes an upper cylinder 21, an intermediate plate 22 and a lower cylinder 23 from top to bottom.

[0026] The upper cylinder 21 is located above ground level, and its top end is detachably connected to the upright 11 of the ranging unit 10. The lower end of the upright 11 is divided into a lower rod 111. A horizontal circular base 112 is welded and fixed to the lower end of the lower rod 111. The base 112 is fixed to the upper cylinder 21 at its lower end by bolts and flanges. The lower cylinder 23 is completely below ground level. To ensure its stability in combination with the surrounding soil, the outer periphery of the lower cylinder 23 is fixed to the surrounding soil by cast-in-place concrete, thereby forming a stable foundation. The intermediate plate 22 is disc-shaped and fixed between the upper cylinder 21 and the lower cylinder 23. Its diameter is significantly larger than that of the upper cylinder 21 and the lower cylinder 23. The intermediate plate 22 is buried underground when the concrete is poured. Due to its large bearing area, it can effectively resist the pressure from the soil above or the pull-out force from the soil below, preventing the entire connecting foundation 20 from settling or floating, and further ensuring the stability of the monitoring reference system.

[0027] like Figure 1-2 , Figure 4 As shown, the monitoring unit 30 is the core unit for deep soil displacement monitoring in this invention. It mainly includes: a deformation tube 34, multiple marker points 32, a measuring trolley 33, and a drive assembly for driving the measuring trolley 33.

[0028] like Figure 1-2 As shown, the deformable tube 34 is a slender, thin-walled tube vertically inserted into the soil layer, made of PVC plastic with good flexibility and elastic recovery. When the surrounding deep soil undergoes horizontal displacement, the deformable tube 34 will undergo smooth bending deformation along with the soil. Multiple marking points 32 are fixedly installed at equal intervals along the axial direction of the deformable tube 34 on the inner or outer wall. The function of these marking points 32 is to divide the deformable tube 34, which undergoes bending deformation, into countless tiny arc segments of equal length. For example, each segment is 0.3 meters long, and the length of the entire deformable tube 34 is 9 meters. That is, the entire deformable tube 34 is divided into 30 measurement segments for processing. The allowable horizontal displacement value for general foundation pit monitoring is <30mm. In subsequent calculations, each tiny arc segment can be approximated as a straight line segment.

[0029] The measuring carriage 33 is the core of the data acquisition unit 30. It is slidably installed inside the deformable tube 34 and moves at a constant speed from top to bottom or bottom to top inside the deformable tube 34 under the drive of the drive component. It performs data acquisition and calculation every time it passes a marker point 32. A high-precision gyroscope (not shown in the figure) is fixedly installed on the measuring carriage 33, which can monitor the vertical tilt angle of the measuring carriage 33 in real time, that is, the angle between its central axis and the absolute plumb line. A passive infrared reflective patch or infrared emitting diode is embedded in each marker point 32. An infrared receiver and signal processing circuit are fixedly installed at the corresponding position on the measuring carriage 33. When the measuring carriage 33 moves to the position directly opposite a marker point 32, the infrared receiver receives the reflected or emitted infrared signal. The signal is shaped by the signal processing circuit and sent to the controller in the control box 13. The controller then reads the measurement value of the gyroscope at the current moment and completes one tilt angle data acquisition.

[0030] Please refer to this carefully. Figure 4-6 As shown, the measuring trolley 33 includes a center plate 331, multiple guide rods 334, two end plates 333, a sliding plate 332, a diagonal brace 352, and a wheel hub 35. The guide rods 334 pass through and are fixedly installed on the center plate 331, and the two ends of the guide rods 334 are respectively fixedly connected to the two end plates 333. Thus, the center plate 331, the guide rods 334, and the end plates 333 together constitute a rigid frame of the trolley.

[0031] The skateboard 332 is located between the center plate 331 and one of the end plates 333, and is slidably mounted on the guide rod 334. One end of the diagonal brace 352 is connected to the center plate 331 by a hinge, and the other end is rotatably mounted with a wheel hub 35. One end of the support rod 339 is hinged to the skateboard 332, and the other end is hinged to the middle of the diagonal brace 352. When the skateboard 332 slides along the guide rod 334, it will push or pull the diagonal brace 352 through the support rod 339, thereby changing the angle between the diagonal brace 352 and the central axis of the center plate 331, and finally realizing the radial extension and retraction of the wheel hub 35 relative to the car frame.

[0032] A threaded sleeve 338 is fixedly installed on the slide plate 332. A lead screw 337 is threaded through the threaded sleeve 338. One end of the lead screw 337 is rotatably mounted on the end plate 333 near the side of the slide plate 332, and the other end is fixedly connected to the output shaft of the first motor 335 fixedly mounted on the center plate 331. The first motor 335 is a dual-output shaft motor, and lead screws 337 with opposite threads are fixedly installed on the output shafts at both ends. When the first motor 335 starts and drives the lead screw 337 to rotate, the threaded sleeve 338 will drive the slide plate 332 to slide linearly on the guide rod 334, thereby accurately adjusting the distance between the hub 35 and the axis of the measuring carriage 33, so that it can tightly press against the inner wall of the deformable tube 34 or the slide rail 341 mentioned later, eliminating gaps and ensuring measurement accuracy.

[0033] In addition, such as Figure 6 As shown, a second motor 336 is also fixedly installed on the diagonal brace 352. A bevel gear 351 is fixedly installed on the output shaft of the second motor 336. A matching bevel gear 351 is also fixedly installed on the rotating shaft of the hub 35. The two bevel gears 351 mesh with each other. When the second motor 336 starts, it can drive the hub 35 to rotate actively through a pair of bevel gears 351, providing the measuring trolley 33 with the power to move, so that it can move more smoothly in the deformable tube 34.

[0034] Example 2: Please see Figure 1-2 and Figure 6 The content is another driving method for driving the measuring trolley 33 to move at a constant speed. The structure includes: a closed ring transmission belt 31, a first fixed pulley 311, a second fixed pulley 312 and a drive motor.

[0035] The transmission belt 31 is made of steel belt or steel wire rope. The two ends of the transmission belt 31 are respectively fitted on the first fixed pulley 311 and the second fixed pulley 312 to form a closed loop. The first fixed pulley 311 is installed inside the lower cylinder 23 of the connecting foundation 20, and the second fixed pulley 312 is installed inside the bottom box 41 of the bottom sealing 40.

[0036] A fixed shaft 313 is fixedly installed on the inner wall of the lower cylinder 23. At the same time, a drive shaft 314 driven by a drive motor (not shown in the figure) is rotatably installed on the side wall of the lower cylinder 23. The fixed shaft 313 is located directly above the drive shaft 314. The first fixed pulley 311 is fixedly installed on the drive shaft 314 and can rotate with it. The transmission belt 31 changes direction by passing around the first fixed pulley 311. The first fixed pulley 311 is kept in a stable position by the constraint of the fixed shaft 313 and the drive shaft 314 on it.

[0037] Similarly, inside the bottom box 41, a stationary shaft 313 and a drive shaft 314 are also installed, and their connection relationship is exactly the same as that inside the lower cylinder 23. The second fixed pulley 312 is also fixedly installed on the drive shaft 314 inside the bottom box 41.

[0038] like Figure 6As shown, the transmission belt 31 has a closed structure with two parallel belt segments (hereinafter referred to as "one spoke" and "the other spoke"). One spoke passes directly through the through holes on the center plate 331, slide plate 332, and end plate 333 of the measuring carriage 33, and does not contact these components. That is, the diameter of the through hole is larger than the diameter of the transmission belt 31, and they can move freely relative to each other. The other spoke of the transmission belt 31 (i.e., the downward moving belt segment) is fixedly connected to the center plate 331, slide plate 332, and end plate 333 through fasteners, pressure plates, and other connecting parts. When the drive motor drives the drive shaft 314 to rotate, causing the transmission belt 31 to circulate, since one spoke of the transmission belt 31 is fixedly connected to the measuring carriage 33, it will directly drive the measuring carriage 33 to move vertically in the deformable tube 34, while the other spoke passes freely through the carriage without interference.

[0039] like Figure 5 As shown, a slide rail 341 is provided on the inner wall of the deformable tube 34, which is adapted to the position of the hub 35 on the measuring trolley 33. The axial direction of the slide rail 341 is strictly parallel to the axial direction of the deformable tube 34. The hub 35 on the measuring trolley 33 is engaged in the slide rail 341. When the second motor 336 drives the trolley to rotate actively or rolls passively with the trolley, the slide rail 341 guides the measuring trolley 33 to move linearly along its axial direction, avoiding trolley swaying or jamming caused by bending of the deformable tube 34 or manufacturing errors.

[0040] like Figure 1 As shown, the bottom seal 40 includes a bottom box 41 with an open top and a sealed bottom. The outer wall of the bottom box 41 is sealed to the inner bottom wall of the deformable tube 34 through a flange and a sealing ring. The bottom box 41 serves as a mounting base for the second fixed pulley 312 and its related shaft, firmly constraining the lower end of the transmission belt 31 to the bottom of the deformable tube 34. On the other hand, it serves as a sealed cavity to prevent groundwater and silt from entering the tube body from the bottom of the deformable tube 34, protecting precision components such as the measuring carriage 33 and the transmission belt 31 from corrosion and contamination.

[0041] Working principle: After the device is installed and the deformable tube 34 is in an absolutely vertical initial state, the driving measuring trolley 33 moves downward from the top of the deformable tube 34 at a constant speed. The trolley travels a constant distance (arc length is...) every time it passes a certain distance... When the gyroscope reaches marker point 32, the controller records the vertical tilt angle measured by the gyroscope. Because the rigid frame of the trolley always remains parallel to the axial direction of the deformable tube 34. That is, the tangent angle corresponding to a tiny arc segment, the arc segment of which is of length. The straight line segment, thus obtained through trigonometric functions. Calculate the horizontal displacement of the upper end of the arc relative to the lower end, and finally sum the horizontal displacements of all marked segments to obtain the total displacement.

[0042] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. A device for monitoring the displacement of a construction site foundation pit, characterized in that, include: A ranging unit (10) is installed above ground. A connecting foundation (20) for providing stable installation support is installed at the lower end of the ranging unit (10). A monitoring unit (30) for monitoring the horizontal displacement of deep soil layers is installed at the lower end of the connecting foundation (20). A bottom seal (40) is installed at the lower end of the monitoring unit (30). The distance measuring unit (10) includes a pole (11), and a distance measuring instrument (12) is fixedly installed on the upper end of the pole (11). The distance measuring instrument (12) can measure the horizontal distance between the pole and a fixed point. The connecting foundation (20) is a cylinder buried in the ground. The upper part of the cylinder is divided into an upper cylinder (21), and the lower part of the cylinder is divided into a lower cylinder (23). The monitoring unit (30) includes a deformation tube (34) vertically inserted into the soil layer. Multiple marker points (32) are fixedly installed at equal intervals on the side wall of the deformation tube (34). A measuring trolley (33) is slidably installed inside the deformation tube (34) and moves uniformly from top to bottom. A gyroscope for monitoring the vertical tilt angle of the measuring trolley (33) is installed on the measuring trolley (33). The measuring trolley (33) is driven by a drive assembly. The gyroscope on the measuring trolley (33) detects the vertical tilt angle once every time the measuring trolley (33) passes a marker point (32). The bottom sealing (40) includes a bottom box (41) with an open top and a sealed bottom, and the bottom box (41) is sealed and installed at the bottom of the deformable tube (34); The upright (11) is detachably connected to the upper cylinder (21), and the lower cylinder (23) is fixed below the ground by cast-in-place concrete around its periphery.

2. The construction site foundation pit displacement monitoring device according to claim 1, characterized in that, The drive assembly includes a transmission belt (31), with its two ends respectively fitted onto a first fixed pulley (311) and a second fixed pulley (312). The first fixed pulley (311) is installed inside the lower cylinder (23). A stationary shaft (313) is fixedly installed on the side of the lower cylinder (23). A drive shaft (314) is also installed inside the lower cylinder (23) and rotatably mounted on its side wall. The input end of the drive shaft (314) is fixedly connected to the output end of the motor. The stationary shaft (313) is located directly above the drive shaft (314). The drive shaft (314) passes through the first fixed pulley (311) and can drive it to rotate. The second fixed pulley (312) is fixedly connected to the first fixed pulley (311).

3. The construction site foundation pit displacement monitoring device according to claim 2, characterized in that, The second fixed pulley (312) is installed in the bottom box (41), and the bottom box (41) is also equipped with a stationary shaft (313) and a drive shaft (314). The connection method between the stationary shaft (313) and the drive shaft (314) and the bottom box (41) is the same as the connection method of the lower cylinder (23). The second fixed pulley (312) is installed on the drive shaft (314), and the drive shaft (314) is located at the upper end of the stationary shaft (313).

4. The construction site foundation pit displacement monitoring device according to claim 3, characterized in that, The measuring trolley (33) includes a center plate (331), on which multiple guide rods (334) are connected and fixed. End plates (333) are fixedly installed at both ends of the guide rods (334). A sliding plate (332) is also installed around the guide rods (334). A diagonal brace (352) is installed on the sliding plate (332). A hub (35) is rotatably installed at the end of the diagonal brace (352) away from the sliding plate (332). The hub (35) contacts the deformable tube (34).

5. The construction site foundation pit displacement monitoring device according to claim 4, characterized in that, The slide plate (332) is slidably mounted on the guide rod (334). The slide plate (332) is hinged to one end of the support rod (339). The other end of the support rod (339) is hinged to the middle of the diagonal brace (352). The end of the diagonal brace (352) away from the hub (35) is hinged to the center plate (331). A threaded sleeve (338) is fixedly mounted on the slide plate (332). A screw rod (337) is threaded inside the threaded sleeve (338). One end of the screw rod (337) is rotatably mounted on the end plate (333), and the other end is fixedly connected to the output shaft of the first motor (335). The screw rod (337) pushes the threaded sleeve (338) to slide on the guide rod (334), thereby adjusting the angle between the diagonal brace (352) and the central axis of the screw rod (337).

6. The construction site foundation pit displacement monitoring device according to claim 5, characterized in that, The transmission belt (31) has a closed structure. One side of the transmission belt (31) passes through the center plate (331), the slide plate (332) and the end plate (333) on the measuring trolley (33) without contacting them. The other side of the transmission belt (31) is fixedly connected to the center plate (331), the slide plate (332) and the end plate (333).

7. The construction site foundation pit displacement monitoring device according to claim 4, characterized in that, A second motor (336) is fixedly installed on the diagonal brace (352). A bevel gear (351) is fixedly installed at the output end of the second motor (336). A bevel gear (351) is also fixedly installed on the rotating shaft of the hub (35). The two bevel gears (351) mesh. After the second motor (336) starts, it drives the hub (35) to rotate.

8. The construction site foundation pit displacement monitoring device according to claim 1 or 7, characterized in that, The inner wall of the deformable tube (34) is provided with a slide rail (341) that matches the position of the hub (35) on the measuring trolley (33). The axial direction of the slide rail (341) is parallel to the axial direction of the deformable tube (34). The slide rail (341) guides the measuring trolley (33) to move linearly along the axial direction on the slide rail (341).

9. The construction site foundation pit displacement monitoring device according to claim 1, characterized in that, An intermediate plate (22) located in the horizontal direction is fixedly installed between the upper cylinder (21) and the lower cylinder (23). The diameter of the intermediate plate (22) is larger than the diameter of the upper cylinder (21) and the lower cylinder (23).

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