A monitoring device and a monitoring method for deformation of a building structure based on millimeter wave radar technology

Abstract

The application provides a kind of method and device for monitoring deformation of surrounding building structures caused by foundation pit excavation based on millimeter wave radar technology, and the monitoring device comprises a cross slide, a PLC (programmable logic controller) all-in-one machine, a laser range finder, a millimeter wave radar and a 4G module, which are used to monitor the deformation of surrounding building structures caused by deep foundation pit excavation. First, the monitoring device is installed at a position away from the impact area of the foundation pit, and then the millimeter wave radar measures the change in the target distance selected. Iterative algorithms are used to correct errors and retrieve accurate values from the data obtained, and finally the coordinate values of each target point are obtained. By analyzing the changes in the target coordinates, the deformation of the surrounding building structures can be determined, thereby monitoring the surrounding environment during the excavation of the foundation pit.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering, and more particularly to the field of monitoring deformation of surrounding buildings and structures caused by foundation pit excavation based on millimeter-wave radar technology. Background Technology

[0002] With the rapid development of urban construction and the increasing number of high-rise buildings, foundation pit construction is trending towards deeper and larger excavations, and the surrounding environment of foundation pits is becoming increasingly complex, including elevated bridges, buildings, subway tunnels, and underground pipelines. Foundation pit excavation alters the surrounding stress field, causing deformation of the surrounding soil and consequently affecting the deformation of surrounding buildings and structures. Excessive deformation of surrounding buildings and structures can damage their structure and shorten their service life. Cases of damage to surrounding buildings and structures caused by foundation pit excavation are frequently reported. Therefore, deformation monitoring of surrounding buildings and structures during foundation pit excavation is a crucial monitoring method in foundation pit engineering. During monitoring, deformation information of surrounding buildings and structures can be obtained in a timely manner. When deformation exceeds the standard, potential hazards can be detected promptly, providing data for taking safety remedial measures. Therefore, monitoring of surrounding buildings and structures in foundation pit engineering has become an indispensable and important part of the engineering construction process.

[0003] To ensure the normal implementation of this step, horizontal displacement and settlement observation in engineering examples usually adopt the direct coordinate method of total station, photogrammetry, and satellite positioning technology (GPS). Although the above traditional monitoring methods can obtain deformation data, they also have certain limitations, mainly in the following aspects: (1) the total station has high workload and low efficiency; (2) the photogrammetry equipment is not suitable for long-distance measurement and has low measurement accuracy; (3) the measurement accuracy of GPS is low and its stability needs to be improved; (4) at the same time, the testing efficiency of the optical system will be greatly affected under poor lighting or bad weather conditions. In recent years, some scholars in the field of civil engineering have also tried new methods for foundation pit monitoring, such as non-contact monitoring technologies such as UAV oblique photography and three-dimensional laser scanning. UAV oblique photography and three-dimensional laser scanning technologies can quickly obtain three-dimensional information of a large area of ​​the ground surface and can effectively display the overall morphology of the slope and the local rock mass characteristics. By comparing the three-dimensional models under different time series, the overall and local change characteristics of the slope can be analyzed. However, whether it is UAV oblique photography or three-dimensional laser scanning technology, its monitoring accuracy is greatly affected by the external environment and it is difficult to achieve long-term continuous monitoring and real-time monitoring and early warning. Therefore, it is often used as an important research tool to analyze the spatial distribution, morphology, scale and evolution of disasters after they occur, but it cannot replace traditional monitoring methods.

[0004] Microwave radar sensing technology, as a special means of distance / displacement measurement, can solve the problem of measuring short-range targets. It has expanded from military to civilian applications and is gradually being applied in areas such as level measurement, target identification, velocity measurement, vibration monitoring, and displacement monitoring. Compared to other sensing technologies, radar sensing technology has unique advantages such as non-contact operation and resistance to rain, fog, and dust, gradually becoming an important sensing method in the field of short-range target displacement measurement. Radar possesses multi-target resolution capabilities, enabling simultaneous measurement of multiple targets. Although microwave radar is used to measure the change in distance between the radar host and the target, it can measure the same target at multiple locations and calculate the target's three-dimensional spatial coordinates using the known spatial relationships between the measurement locations, thereby achieving spatial positioning of the target.

[0005] Wang Yihao and others used microwave radar to monitor deformation and calculated the three-dimensional deformation of the target measurement point. Lan Silian and others studied slope radar for non-contact deformation monitoring and derived the relationship between the displacement of the monitored target and the actual displacement of the landslide body in the main sliding direction vector. Dai Wei and others used a monitoring technology that combined ground-based synthetic aperture radar with three-dimensional laser scanning to achieve real-time monitoring of the overall three-dimensional deformation of the slope. Ding Hui and others found that real aperture radar has strong adaptability and high resolution in open-pit coal mines. The IBIS system based on synthetic aperture radar developed by the Italian company IDS and the University of Florence can continuously, comprehensively, and with high precision monitor ground facilities. Ding Zhen and others used aperture radar in open-pit slope research and concluded that slope monitoring radar has high monitoring accuracy and is less affected by environmental factors.

[0006] At present, radar has demonstrated good performance in monitoring slope deformation. However, it still has the following disadvantages: (1) Complex data interpretation: The amount of data obtained by radar monitoring of slopes is large and complex, requiring professional technicians to interpret and analyze the data in order to obtain useful monitoring information. This may be difficult for general users. (2) High cost: Radar monitoring of slopes requires specialized monitoring equipment and technical support, which are relatively expensive. At the same time, long-term maintenance and use also require a certain amount of funding. (3) Requires a long monitoring period: Slope deformation is usually a slow process, requiring a long monitoring period to obtain accurate data. In addition, the above technology is mainly applied to the field of slope monitoring and has not been applied to the deformation monitoring of structures around the foundation pit. This is obviously insufficient for engineering projects that need to understand the deformation of structures around the foundation pit in a timely manner.

[0007] With the development of radar technology, some scholars have improved radar monitoring methods to address the problems mentioned above in monitoring the excavation process of foundation pits, enabling real-time monitoring of foundation pit deformation. For example:

[0008] The method and device for detecting deformation of surrounding rock in wells proposed by Zhao Yinan and Feng Xiang (CN112611316A) involves measuring the distance to a target point at different locations and then obtaining the coordinates of the target point in a set spatial coordinate system through analytical geometric relationships. The resulting coordinate changes are then analyzed to assess the deformation of the surrounding rock. However, this method, due to its direct solution approach, often suffers from errors in radar ranging, leading to situations where coordinates cannot be determined or are incorrectly determined, resulting in significant dispersion. To obtain millimeter-level deformation solutions, radar accuracy must be less than millimeters, which current direct radar ranging technology cannot meet. Furthermore, this method can only measure a single target point. This patent utilizes an iterative algorithm to calculate coordinates, avoiding the problem of unsolvable coordinates; it can also measure multiple target points, better meeting the needs of monitoring deformation and displacement.

[0009] The two-dimensional surface deformation monitoring system (CN208721024U) proposed by Liu Zhong and Deng Feng, based on microwave interferometry, obtains the deformation components of the two-dimensional surface in the horizontal and vertical directions by measuring a stabilized body and the object under test using radar, thus achieving the purpose of deformation monitoring. Obviously, this method can only measure deformation in the horizontal and vertical directions. However, the deformation of foundation pits and surrounding structures is more complex. The three-dimensional monitoring scheme provided by this patent better meets actual monitoring needs. Furthermore, setting a stabilized body for comparison is an idealized method. In the actual situation of foundation pit excavation, it is impossible to guarantee that the stabilized body will not deform or displace. The method of setting and using the initial position coordinates of the radar in this patent is more reasonable. At the same time, this method requires two radars for monitoring, which is much more expensive than the monitoring method of this patent using only one radar.

[0010] Ye Lei's proposed deformation measurement method and radar system (CN111351424B) obtains the line-of-sight deformation through signal difference, and then calculates the vertical and / or horizontal displacement of the monitored target based on the radar device's installation parameters, the first line-of-sight deformation, and the second line-of-sight deformation. Clearly, this method can only measure deformation in the horizontal and vertical directions, and it has very high requirements for the radar device's installation parameters. The angle is calculated from the installation height and distance, and the accuracy of these parameters is difficult to guarantee, which can cause errors or even mistakes in the subsequently calculated coordinates, lacking corrective measures. This patent overcomes this deficiency by using an iterative algorithm to fit the distance.

[0011] Therefore, there is an urgent need to develop a monitoring method and device suitable for this field to address the deformation of the surrounding environment caused by ultra-deep foundation pit excavation. Summary of the Invention

[0012] The present invention aims to propose a monitoring method and device for the surrounding environment during the foundation pit excavation process based on millimeter-wave radar. This method can effectively monitor the deformation of existing buildings and structures in the impact zone of foundation pit excavation, ensure project safety, reduce losses, and provide a new monitoring technology for the monitoring of the impact of ultra-deep foundation pit excavation on the surrounding environment in the field of geotechnical engineering.

[0013] This invention provides a monitoring device for building deformation based on millimeter-wave radar technology. The building deformation is caused by foundation pit excavation. The monitoring device includes a cross slide, a PLC (Programmable Logic Controller) integrated machine, a laser rangefinder, a millimeter-wave radar, and a 4G module.

[0014] Preferably, the cross slide includes two one-dimensional sliding controllers and an adapter plate; the two one-dimensional sliding controllers intersect in a cross shape, and the adapter plate bolts the base of the upper one-dimensional sliding controller to the slide of the lower one-dimensional sliding controller, thereby forming a cross slide; the cross slide can achieve precise displacement control at any point in the plane; the one-dimensional sliding controller is an electric servo high-precision displacement device, including a slide, a threaded rod, a servo control motor, a base, and a connector; the slide is mounted on the threaded rod, and the servo control motor drives the threaded rod to rotate, thereby achieving precise displacement control of the slide.

[0015] Preferably, the PLC (Programmable Logic Controller) integrated machine is connected to the cross slide via a communication cable, and has the function of setting the working mode of the slide and controlling the movement posture of the cross slide, including but not limited to controlling the timed start and timed stop of the slide.

[0016] Preferably, the laser rangefinder is a high-precision rangefinder instrument, mounted on a slide table.

[0017] Preferably, the millimeter-wave radar is fixed to the slide of the cross slide by bolts, and the movement of the cross slide is controlled by a PLC (Programmable Logic Controller) integrated machine, thereby realizing the precise movement of the millimeter-wave radar.

[0018] Preferably, the 4G module is connected to the millimeter-wave radar via a communication cable, enabling remote control of the millimeter-wave radar, collection of data measured by the millimeter-wave radar, and uploading of the data to a cloud server.

[0019] On the other hand, the present invention provides a monitoring method for monitoring the deformation of buildings and structures around an excavated foundation pit using the aforementioned monitoring device, the monitoring method comprising the following steps:

[0020] Step 1: Select the location for the monitoring device and install it; the spatial coordinates of the installation location of the monitoring device should not be affected by the excavation of the foundation pit, and it should be able to monitor the selected target point P without obstruction.

[0021] Step 2: Install the radar reflector; the concave angle of the radar reflector should be basically aligned with the monitoring device to increase the identification capability of the millimeter-wave radar; the allowable angular difference for the basically aligned direction is 10%;

[0022] Step 3: After adjusting the cross slide to its initial position, select three coordinates on the cross slide as the moving positions of the millimeter-wave radar, denoted as points A, B, and C, and their coordinates are marked as A(x). A y A , z A B(x) B y B , z B ), C(x) C y C , z C );

[0023] Step 4: Using a high-precision laser rangefinder, measure the initial distances between points A, B, and C and the monitoring target point P, and record them as L. A0 L B0 L C0 ;

[0024] Step 5: Use an iterative algorithm to search and calculate the initial coordinates of the monitoring target point P, denoted as P(x). p0 y p0 , z p0 );

[0025] Step 6: The changes in distance between the monitoring device and the target point P at points A, B, and C are recorded as ΔL. A ΔL B ΔL C ; Calculate the distances between the monitored target point after deformation and points A, B, and C, respectively, L A =L A0 +ΔL A L B =L B0 +ΔL B L C =L C0 +ΔL C ;

[0026] Step 7: Use an iterative algorithm to search and calculate the coordinates of the deformed monitoring target point P, denoted as P(x p y p , z p );

[0027] Step 8: Subtract the initial coordinates from the deformed coordinates of the monitoring target point P to obtain the three-dimensional deformation of the monitoring target; at the same time, update the coordinates of the deformed monitoring target point to the initial coordinates, and update the distances between the deformed monitoring target point and points A, B, and C to the initial distances;

[0028] Step 9: Repeat steps 6 to 8, and monitor according to the cyclic measurement interval to achieve continuous observation of the monitoring target point.

[0029] Preferably, multiple monitoring targets can be set in step 2, requiring that the distance between target points in the plane be greater than 0.5m and the distance in the depth direction be greater than 0.1m.

[0030] Preferably, the iterative algorithm in step 5 can solve for the coordinates of the monitoring target point, and its core algorithm is:

[0031] (1) Calculate the distances between the monitored target point after deformation and points A, B, and C, respectively, L. A =L A0 +ΔL A L B =L B0 +ΔL B L C =L C0 +ΔL C When the initial coordinates, i.e., the target point, have not moved, ΔL A =ΔL B =ΔL C =0;

[0032] (2) Take the differential variables Δx, Δy, and Δz, and perform search calculations over the specified search interval, denoted as Δx∈[0, Δx], Δy∈[0, Δz]. p ]、Δy∈[0,ΔY p ]、Δz∈[0,ΔZ p The microvariable depends on the search accuracy; the smaller the value, the higher the accuracy. The search interval is determined based on the estimated maximum deformation of the monitored target within a single frequency range.

[0033] (3) Calculate the hypothetical distance between the monitored target point and the millimeter-wave radar, and denote the hypothetical distance between the target point and points A, B, and C as L. m L n L s The calculation formula is:

[0034]

[0035]

[0036]

[0037] Where: Δx i Δy j Δz k Let Δx, Δy, and Δz be the values ​​at steps i, j, and k, respectively, where i ∈ [0, Δx, Δy, Δz]. p / Δx], j∈[0, ΔY] p / Δy]、k∈[0,ΔZ p / Δz];

[0038] (4) Calculate the distance error using the following formula:

[0039]

[0040] (5) Output Δσ ijk Value and corresponding monitoring target point coordinates (x) p0 +Δx i y p0 +Δy j , z p0 +Δz k );

[0041] (6) Comparison of Δσ ijk The minimum value is taken as the coordinate of the target point after deformation.

[0042] Preferably, the cyclic measurement interval in step 9 can be controlled by a PLC (Programmable Logic Controller) integrated machine, which can realize automatic start and stop functions. The specific frequency is determined according to the actual project.

[0043] The present invention has the following beneficial effects:

[0044] 1) The monitoring system used in this invention can start and stop at set times. It is a highly automated system that can greatly reduce labor costs.

[0045] 2) The millimeter-wave radar used in this invention is less affected by weather conditions and is more adaptable to various environments compared to traditional optical instruments.

[0046] 3) The millimeter-wave radar used in this invention is lower in cost than synthetic aperture radar, and has greater advantages when the budget is low.

[0047] 4) The monitoring method used in this invention can obtain more target data in the same amount of time, and is more rigorous and detailed in terms of monitoring.

[0048] 5) The 4G module used in this invention can process data in the cloud and analyze the stability of the surrounding environment during the excavation of the foundation pit, which is more conducive to safe construction. Attached Figure Description

[0049] Figure 1 A schematic diagram of the case monitoring profile.

[0050] Figure 2 A schematic diagram of the implementation case monitoring.

[0051] Figure 3 For monitoring devices. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0053] This embodiment applies the monitoring device and method for monitoring the deformation of surrounding buildings caused by foundation pit excavation based on millimeter-wave radar technology, provided by the present invention, to the monitoring of deformation of surrounding buildings in a foundation pit project.

[0054] The monitoring device consists of the following components:

[0055] The monitoring device includes a cross slide, a PLC (Programmable Logic Controller) integrated unit, a laser rangefinder, a millimeter-wave radar, and a 4G module. The cross slide consists of two one-dimensional sliding controllers and an adapter plate. The two one-dimensional sliding controllers are interlocked, and the adapter plate bolts the base of the upper one-dimensional sliding controller to the slide of the lower one-dimensional sliding controller, thus forming the cross slide. The cross slide can achieve precise displacement control at any point in a plane. The x-axis and y-axis travel range of the cross slide is 500mm, and the slide's movable range on the slide rail is 500mm × 500mm. The one-dimensional sliding controller is a high-precision electric servo displacement device, consisting of a slide, a threaded rod, a servo control motor, a base, and connecting parts. The slide is mounted on the threaded rod, and the servo control motor drives the threaded rod to rotate, thereby achieving precise displacement control of the slide. The PLC integrated unit is connected to the cross slide via a communication cable and has the function of setting the slide's working mode and controlling the cross slide's movement posture, including but not limited to controlling the slide's timed start and stop. The laser rangefinder is a high-precision ranging instrument mounted on a sliding table. Its measurement range is 0-300 meters, with a measurement accuracy of 0.01 meters. While the accuracy is low, it meets the requirements for estimating target positions. The millimeter-wave radar is bolted to the sliding table and its movement is controlled by a PLC, enabling precise movement of the millimeter-wave radar. The millimeter-wave radar has a measurement range of 0-300 meters and a deformation recognition accuracy of up to 0.02 mm, meeting the monitoring requirements for settlement and deformation of buildings surrounding ultra-deep foundation pits. A 4G module connects to the millimeter-wave radar via a communication cable, allowing for remote control of the radar, collection of data measured by the millimeter-wave radar, and uploading of the data to a cloud server.

[0056] The monitoring method for deformation of surrounding buildings and structures is mainly achieved through the following steps:

[0057] Step 1: The monitoring device is installed 100m away from the edge of the foundation pit, avoiding the area affected by the foundation pit excavation, and is transparent to the monitoring point target without obstruction.

[0058] Step 2: Select 3 monitoring target points on existing buildings within the impact zone of the foundation pit and install radar reflectors; the concave angle of the radar reflector should be as close as possible to the monitoring device to increase the identification capability of the millimeter-wave radar.

[0059] Step 3: After adjusting the cross slide to its initial position, select three coordinates as the moving positions of the millimeter-wave radar, denoted as points A, B, and C. Using the plane where the slide is located as the reference coordinate system (xy plane) and the vertical direction as the z-axis, determine a coordinate system. The coordinates of points A, B, and C are denoted as A(x...). A y A , z A B(x) B y B , zB ), C(x) C y C , z C ).

[0060] Step 4: Using a high-precision laser rangefinder, measure the initial distances between points A, B, and C and the monitoring target points P1, P2, and P3. The distance from A to P1 is denoted as L. A1 The distance from A to P2 is denoted as L. A2 The distance from A to P3 is denoted as L. A3 The distance from B to P1 is denoted as L. B1 The distance from B to P2 is denoted as L. B2 The distance from B to P3 is denoted as L. B3 The distance from C to P1 is denoted as L. C1 The distance from C to P2 is denoted as L. C2 The distance from C to P3 is denoted as L. C3 ; Specific values ​​are shown in Table 1:

[0061] Table 1 Initial distance of radar to target point

[0062] <![CDATA[L A1 ]]> 210685.87 <![CDATA[L B1 ]]> 211011.27 <![CDATA[L C1 ]]> 211284.44 <![CDATA[L A2 ]]> 210889.46 <![CDATA[L B2 ]]> 211214.80 <![CDATA[L C2 ]]> 211485.41 <![CDATA[L A3 ]]> 210591.81 <![CDATA[L B3 ]]> 210915.20 <![CDATA[L C3 ]]> 211187.32

[0063] Step 5: Use an iterative algorithm to search and calculate the initial coordinates of the monitoring target point. Based on the measured distance, roughly estimate the target coordinates P1(x1, y1, z1), P2(x2, y2, z2), and P3(x3, y3, z3).

[0064] Table 2 Initial coordinates of the target

[0065] P1 -3557.67 -210453.54 600.00 P2 -2799 -210791 0.00 P3 -1428 -211078 53

[0066] The core algorithm for implementing the above iterative algorithm is:

[0067] (1) Calculate the distances between the monitored target point after deformation and points A, B, and C, respectively, L. A =L A1 L B =L B1 L C =L C1 .

[0068] (2) Take the infinitesimal variables Δx = Δy = Δz = 0.5 mm and perform search calculations on the specified search interval, which is denoted as Δx∈[0, 50], Δy∈[0, 50], and Δz∈[0, 50].

[0069] (3) Calculate the hypothetical distance between the monitored target point and the millimeter-wave radar, and denote the hypothetical distance between the target point and points A, B, and C as L. m L n L s The calculation formula is:

[0070]

[0071]

[0072]

[0073] Where: Δx i Δy j Δz k Let Δx, Δy, and Δz be the values ​​when they reach the i, j, and kth steps, respectively, where i ∈ [0, 100], j ∈ [0, 100], and k ∈ [0, 100].

[0074] (4) Calculate the distance error using the following formula:

[0075]

[0076] (5) Output Δσ ijk Value and corresponding monitoring target point coordinates (x) p0 +Δx i y p0 +Δy j , z p0 +Δz k ).

[0077] (6) Comparison of Δσ ijk The minimum value is taken as the coordinate of the target point after deformation.

[0078] Step 6: The monitoring device begins measurement. The equipment operates sequentially according to time. Both the slide rail and radar start working according to the preset time sequence. For example, at the start of the measurement plan, the time is set to 00:00:00. At this time, the radar is in standby mode. The slide rail starts to control the movement of the slide table, moving the slide table and radar to position A. After reaching position A, the slide table stops and waits until the designated time 00:10:00. The radar then begins to measure the target, obtaining the change in distance between position A and P1, recorded as a1; the change in distance between position A and P2, recorded as a2; and the change in distance between position A and P0, recorded as a0. After the measurement is completed and the data is recorded, the radar goes into standby mode again. At the designated time 00:20:00, the slide table starts to move towards position B. After reaching position B, the slide table stops and waits until the designated time 00:20:00. At the designated time 00:30:00, the radar begins measuring the target, obtaining the distance change between position B and P1, denoted as b1; the distance change between position B and P2, denoted as b2; and the distance change between position B and P0, denoted as b0. After the measurement is completed and the data is recorded, the radar goes into standby mode again. At the designated time 00:40:00, the slide begins to move towards position C. After reaching position C, the slide stops and waits until the designated time 00:50:00, when the radar begins measuring the target again. After the measurement is completed and the data is recorded, the radar goes into standby mode again. When the measurement is completed at position C and c1c2c0 is recorded, the first measurement cycle is completed, and both the radar and the slide enter standby mode, waiting for the next designated time 02:00:00, at which time the slide and radar will return to position A to begin the next measurement cycle. The measurement operation is set to a 2-hour cycle, and can be cycled 12 times in 24 hours. When the time reaches 24:00:00, it will reset to 00:00:00 without affecting the measurement cycle. Table 3 shows the cycle command configuration for the slide and millimeter-wave radar.

[0079] Table 3. A Cyclic Command for Slide Table and Millimeter-Wave Radar

[0080]

[0081] Step 7: After monitoring begins, the results can be obtained as shown in Table 4 after one monitoring cycle. The change in distance between position A and P1 is denoted as a1; the change in distance between position B and P1 is denoted as b1; and the change in distance between position C and P1 is denoted as c1.

[0082] Table 4 Changes in the distance to the target point after deformation

[0083]

[0084]

[0085] The distance from the radar's initial position A to the target point P1 is denoted as L1, where L1 = L A1+a1; Similarly, L2 and L3 are the distances from the measured initial radar positions B and C to the target point P1, where L2 = L B1 +b1, L3=L C1 +c3. The distance from point A to the target point P2 is denoted as L4, where L4 = L A2 +a2; Similarly, L5 and L6 are the distances from the measured initial radar positions B and C to the target point P2, where L5 = L B2 +b2, L6=L C2 +c2. The distance from point A to the target point P3 is denoted as L7, where L7 = L A3 +a3; Similarly, L8 and L9 are the distances from the measured initial radar positions B and C to the target point P3, where L8 = L B3 +b3, L9 = L C3 +c3. See Table 5 for specific distance results.

[0086] Table 5 Distance to target point after deformation

[0087] <![CDATA[L1]]> 210686.15 <![CDATA[L2]]> 211011.63 <![CDATA[L3]]> 211284.00 <![CDATA[L4]]> 210889.68 <![CDATA[L5]]> 211214.46 <![CDATA[L6]]> 211485.53 <![CDATA[L7]]> 210591.59 <![CDATA[L8]]> 210915.98 <![CDATA[L9]]> 211186.38

[0088] The coordinates of the monitored target point P after deformation are obtained by using an iterative algorithm, and the coordinates are denoted as P(x). p y p , z p To implement the above coordinate calculation, we will take monitoring point P1 as an example. We take the infinitesimal variables Δx = Δy = Δz = 0.5 mm and perform a search calculation over a specified search interval, denoted as Δx∈[0, 50], Δy∈[0, 50], and Δz∈[0, 50]. The assumed distance is calculated using the following formula:

[0089]

[0090]

[0091]

[0092] Where: Δx i Δy j Δz k Let Δx, Δy, and Δz be the values ​​when they reach the i, j, and kth steps, respectively, where i ∈ [0, 100], j ∈ [0, 100], and k ∈ [0, 100].

[0093] L was calculated m L n L s Then, calculate the distance error using the following formula:

[0094]

[0095] Output Δσ ijk Value and corresponding monitoring target point coordinates (x) p0 +Δx i y p0 +Δy j , z p0 +Δz k Compare Δσ ijk The minimum value is taken as the coordinate value of the monitored target point after deformation, and the results are shown in Table 6.

[0096] Table 6 Coordinates of monitoring target point P1 after deformation

[0097] <![CDATA[P1]]> -0.5 0 0.5 -3558.17 -210453.54 600.50

[0098] Similarly, according to the established algorithm, the coordinates of P2 and P3 can be obtained.

[0099] Table 7 Coordinates of monitoring target points P2 and P3 after deformation.

[0100] <![CDATA[P2]]> -2799.5 -210791.5 -0.5 <![CDATA[P3]]> -1427.5 -211077.5 52.5

[0101] Step 8: Subtract the initial coordinates from the deformed coordinates of the monitoring target point P to obtain the three-dimensional deformation of the monitoring target. At the same time, update the coordinates of the deformed monitoring target point to the initial coordinates, and update the distances between the deformed monitoring target point and points A, B, and C to the initial distances.

[0102] Step 9: Repeat steps 6 to 8 to achieve continuous observation of the target monitoring point.

Claims

1. A monitoring method for monitoring the deformation of buildings and structures surrounding an excavated foundation pit using a monitoring device, wherein the monitoring device is a building and structure deformation monitoring device based on millimeter-wave radar technology, the deformation of the building and structure is caused by the excavation of the foundation pit, and the monitoring device includes a cross slide, a PLC (Programmable Logic Controller) integrated machine, a laser rangefinder, a millimeter-wave radar, and a 4G module. The monitoring method includes the following steps: Step 1: Select the location for the monitoring device and install it; the spatial coordinates of the installation location of the monitoring device should not be affected by the excavation of the foundation pit, and it should be able to monitor the selected target point P without obstruction. Step 2: Install the radar reflector; The radar reflector concave angle is required to be substantially aligned with the monitoring device to increase the identification capability of the millimeter-wave radar; the allowable angular difference for this substantially aligned alignment is 10%. Step 3: After adjusting the cross slide to its initial position, select three coordinates on the cross slide as the moving positions of the millimeter-wave radar, denoted as points A, B, and C, with the coordinates marked as follows: , , ; Step 4: Using a high-precision laser rangefinder, measure the initial distances between points A, B, and C and the monitoring target point P, and record them as follows: , , ; Step 5: Use an iterative algorithm to search and calculate the initial coordinates of the monitoring target point P, denoted as: The iterative algorithm described above can solve for the coordinates of the monitoring target point. Its core algorithm is as follows: (1) Calculate the distances between the monitored target point and points A, B, and C after deformation, respectively. , , When the initial coordinates, i.e., the target point, have not moved, ; (2) Take the infinitesimal variable , , Perform search calculations over a specified search interval, denoted as . , ; The value of the micro-variable depends on the search accuracy; the smaller the value, the higher the accuracy. The search interval is determined based on the estimated maximum deformation of the monitored target within a single frequency range. (3) Calculate the hypothetical distance between the monitored target point and the millimeter-wave radar, and denote the hypothetical distances between the target point and points A, B, and C as follows: , , The calculation formula is: in: , , They are respectively , , The search results were found to be... , , The value at step time, , , The values ​​are respectively , , ; (4) Calculate the distance error using the following formula: (5) Output Values ​​and corresponding monitoring target point coordinates ; (6) Comparison The coordinates corresponding to the minimum value are taken as the coordinates of the monitored target point after deformation; Step 6: The changes in distance between the monitoring device and the target point P at points A, B, and C are recorded as follows: , , ; Calculate the distances between the monitored target point after deformation and points A, B, and C, respectively. , , ; Step 7: Use an iterative algorithm to search and calculate the coordinates of the deformed monitoring target point P, denoted as: ; Step 8: Subtract the initial coordinates from the deformed coordinates of the monitoring target point P to obtain the three-dimensional deformation of the monitoring target; at the same time, update the coordinates of the deformed monitoring target point to the initial coordinates, and update the distances between the deformed monitoring target point and points A, B, and C to the initial distances; Step 9: Repeat steps 6 to 8, and monitor according to the cyclic measurement interval to achieve continuous observation of the monitoring target point.

2. The monitoring method according to claim 1, characterized in that, In step 2, multiple monitoring targets are set, and the target points are required to be more than 0.5m apart in the plane and more than 0.1m apart in the depth direction.

3. The monitoring method according to claim 1, characterized in that, The cyclic measurement interval in step 9 can be controlled by a PLC (Programmable Logic Controller) integrated machine, which can realize automatic start and stop functions. The specific frequency is determined according to the actual project.

4. The monitoring method according to claim 1, wherein the cross slide table comprises two one-dimensional sliding controllers and an adapter plate; the two one-dimensional sliding controllers intersect in a cross shape, and the adapter plate bolts the base of the upper one-dimensional sliding controller to the slide table of the lower one-dimensional sliding controller, thereby forming a cross slide table; the cross slide table can achieve precise displacement control of any point in the plane; the one-dimensional sliding controller is an electric servo high-precision displacement device, comprising a slide table, a threaded rod, a servo control motor, a base, and a connector; the slide table is mounted on the threaded rod, and the servo control motor drives the threaded rod to rotate, thereby achieving precise displacement control of the slide table.

5. According to the monitoring method of claim 1, the PLC (Programmable Logic Controller) integrated machine is connected to the cross slide via a communication cable, and has the function of setting the working mode of the slide and controlling the movement posture of the cross slide, including but not limited to controlling the timed start and timed stop of the slide.

6. The monitoring method according to claim 1, wherein the laser rangefinder is a high-precision rangefinder instrument and is mounted on a slide table.

7. In the monitoring method according to claim 1, the millimeter-wave radar is fixed to the slide of the cross slide by bolts, and the movement of the cross slide is controlled by a PLC (Programmable Logic Controller) integrated machine, thereby realizing the precise movement of the millimeter-wave radar.

8. The monitoring method according to claim 1, wherein the 4G module is connected to the millimeter-wave radar via a communication cable, and can remotely control the millimeter-wave radar, collect the data measured by the millimeter-wave radar, and upload the data to a cloud server.

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