WO2019196771A1

WO2019196771A1 - System and method for measuring deformation of foundation pit

Info

Publication number: WO2019196771A1
Application number: PCT/CN2019/081692
Authority: WO
Inventors: 永远; 贺正琦; 高远瞩; 张仲瑞; 李盼召
Original assignee: 成都柏森松传感技术有限公司
Priority date: 2018-04-10
Filing date: 2019-04-08
Publication date: 2019-10-17
Also published as: CN108519044A

Abstract

Disclosed is a system and method for measuring the deformation of a foundation pit. The system for measuring the deformation of a foundation pit comprises a deformation measurement part (1.0) arranged on each foundation pit deformation measuring point and used for measuring the amount of deformation of the foundation pit at the measuring point. The deformation measurement part comprises a steel wire (1.1) and a sensor module (1.2); the bottom end of the steel wire (1.1) is fixed to the bottom of the foundation pit close to a side wall of the foundation pit, and the top end of the steel wire (1.1) is fixedly connected to an upper edge of the side wall of the foundation pit; the sensor module (1.2) comprises an inclination angle sensor (1.2a) for measuring the inclination angle of the steel wire (1.1); the deformation measuring part (1.0) is installed before measurement starts; and during installation, the steel wire (1.1) is pre-tensioned such that the steel wire (1.1) is in a vertically stretched state. The measuring system and method can efficiently, precisely and stably monitor the deformation of the foundation pit.

Description

Measuring system and measuring method for foundation pit deformation

Technical field

The invention relates to a measuring system and a measuring method capable of real-time monitoring deformation of a foundation pit, and belongs to the field of base pit deformation measurement.

Background technique

With the continuous advancement of urbanization, the space utilization rate of modern cities is getting higher and higher, the congestion of cities is becoming more and more serious, and the development and utilization of urban underground space has become an inevitable trend of urban development. The use of a large number of underground spaces such as underground parking lots, underground shopping malls and underground tunnels has led to the indispensable excavation of underground deep foundation pits.

After the excavation of the foundation pit, the horizontal support force of the soil is reduced, and the precipitation caused by the excavation of the foundation pit causes the groundwater level to decrease and the water level outside the pit to be unbalanced, resulting in a large difference in water pressure and an increase in the self-weight stress in the soil. It may cause the surrounding important buildings and the ground to sink, lateral deformation, inclination, displacement, and even cracking, affecting important buildings and personnel, construction safety; in addition, considering the existing foundation pit support design method and geological conditions, support The protection program cannot completely guarantee the absolute safety of the foundation pit works. Therefore, monitoring the construction of foundation pits is necessary for the safety of important buildings and personnel in the surrounding area as well as the foundation pit works themselves.

At present, most of the methods used for foundation pit monitoring are the total station coordinate change method. The total station coordinate change method is to set several differential reference points in any stable and firm place outside the influence of the foundation pit construction, and install a permanent reflection prism on the differential reference point and the deformation monitoring point. According to the shape of the foundation pit, a station is arbitrarily set to observe the three-dimensional coordinates of each point. Data from multiple observations are used as a benchmark for future deformation monitoring data processing after differential and flat difference. Three-dimensional observation of horizontal displacement and vertical displacement is performed one or several cycles per day; starting from the second observation, each station does not require the same coincidence with the previous one, but the differential reference point must be used to measure the three-dimensional measurement of the station. coordinate. Then, the coordinates of the respective monitoring points are calculated and measured. The difference adjustment calculates the deformation value and the settlement direction deformation value of each monitoring point in the horizontal direction, that is, the deformation value in the three-dimensional direction. According to the shape of the edge of different foundation pits, the value of the displacement value in the three-dimensional direction is converted into the horizontal displacement value and the vertical settlement value in the normal direction of the pit edge.

Foundation pit monitoring has high requirements on data accuracy and monitoring frequency. Although the total station coordinate change method is simple to operate, it is required to be observed by one or several cycles per day due to manual operation. The labor is very large and cannot be realized. Real-time measurement and easy to produce measurement error. Moreover, the total station coordinate change method can only measure the horizontal displacement of the foundation pit, and can not measure the vertical settlement of the foundation pit, and the vertical settlement of the foundation pit is also a very important safety indicator. In the modern urban construction, these shortcomings have brought about the safety hazards of deep foundation pit construction. Due to the imperfection of these detection systems, many engineering accidents have been caused. Therefore, researching and designing an efficient, accurate and stable real-time foundation pit deformation monitoring technology has become a technical problem that technicians in the field urgently need to solve.

Summary of the invention

It is an object of the present invention to provide a measurement system and a measurement method for deformation of a foundation pit. The foundation pit measuring system and measuring method can efficiently, accurately and stably monitor the deformation of the foundation pit.

The invention achieves the object of the invention. Firstly, a measuring system for deformation of a foundation pit is provided, which comprises a deformation measuring portion which is arranged at a deformation measuring point of each foundation pit to measure the deformation amount of the foundation pit, and the structural characteristic is: the deformation measurement The portion includes a wire and a sensor module, the bottom end of the wire is fixed to the bottom of the pit near the sidewall of the pit, and the top end of the wire is fixedly connected to the upper edge of the sidewall of the pit; the sensor module includes a tilt angle for measuring the tilt angle of the wire Sensor; before the start of measurement, the deformation measuring unit is installed; during installation, the steel wire is pre-tensioned and the steel wire is vertically stretched.

The invention also provides two measuring methods for the above-mentioned foundation pit deformation measuring system. The first measuring method is: real-time monitoring the angle value θ measured by the inclination sensor, and determining the horizontal displacement of the foundation pit according to the measured angle value θ X, X = 2πh * θ / 360 °, where h is the initial pit depth. The second measurement method is: monitoring the angle value θ measured by the inclination sensor in real time, and determining the horizontal displacement X, X=h*tanθ of the foundation pit according to the measured angle value θ, where h is the initial pit depth.

When the foundation pit is horizontally displaced, the upper edge of the side wall of the foundation pit will drive the horizontal displacement of the top end of the steel wire, and the bottom end of the steel wire is fixed, so the steel wire will deflect relative to the vertical direction, and the angle indicated by the inclination sensor is the wire around the bottom. The rotation angle θ of the fixed point. Since the horizontal displacement is very small compared with the initial pit depth h, the horizontal displacement can be approximated by the arc length formula X=2πh*θ/360°; the horizontal displacement can also be approximated by the sine formula X=h*tanθ . After calculation, the inclination sensor with an accuracy of 0.01° is used. When the initial pit depth is 15 meters, the measurement accuracy of the above two measurement methods on the horizontal displacement is about 2.5 mm. The warning value required for the detection of the 15-meter foundation pit in the project is 3mm. Therefore, the measurement system and measurement method are in full compliance with the foundation pit measurement requirements.

Compared with the prior art, the above beneficial effects of the base pit deformation measurement and measurement method are:

1. The measuring system and measuring method can replace the existing total station and other measuring methods, which greatly reduces the work intensity of the staff and saves the labor cost. The data can be visually displayed to the testing personnel through the inclination sensor measurement, and the detecting personnel are not Professional requirements; and can be developed to form remote automatic monitoring, without the need for staff to monitor the site.

Second, the cost of a set of deformation measurement department of the measurement system is less than 700 yuan, which is greatly reduced compared with the total station cost.

Third, the measurement system and measurement method can replace the existing total station and other measurement methods, and the detection accuracy is high.

4. Each deformation measurement part of the whole set of measurement system can be flexibly controlled according to the actual measurement requirements of the foundation pit.

The present invention achieves another object of the invention, and provides a deformation measuring system for a foundation pit, comprising a deformation measuring portion for measuring a deformation amount of a foundation pit at each of the deformation measuring points of the foundation pit, the structural feature of which is: the deformation measurement The portion includes a spring, a wire and a sensor module, the sensor module includes a tilt sensor for measuring the tilt angle of the wire and a displacement sensor for measuring the amount of spring expansion; the bottom end of the wire is fixed to the bottom of the pit near the side wall of the pit The top end of the wire is connected to one end of the spring, and the other end of the spring is fixedly connected to the upper edge of the side wall of the pit; before the measurement starts, the deformation measuring part is installed; when installing, the spring and the wire are pre-tensioned, and the wire and the spring are made It is in a vertical stretch state.

Further, the spring of the present invention has an elastic modulus of 0.5 to 2 N/mm.

Through experiments, the spring with elastic coefficient of 0.5~2N/mm can be used to ensure that the spring and the steel wire can be fully pre-tightened in the initial state. When the horizontal displacement occurs at the upper edge of the sidewall of the foundation pit, the steel wire and the spring are tilted as a whole to utilize the inclination sensor. Measuring the angle, calculating the horizontal displacement at the upper edge of the side wall of the foundation pit; and ensuring the vertical displacement of the foundation pit (base pit settlement), the deformation of the steel wire and the spring in the vertical direction will be concentrated in the spring portion, which can be passed The displacement sensor measures the amount of expansion and contraction of the spring to obtain the vertical displacement of the foundation pit.

Further, the displacement sensor of the present invention measures the amount of spring expansion and contraction in a specific manner: the displacement sensor is connected in parallel with the spring, and one end of the displacement sensor is connected to the top end of the steel wire, and the other end is fixedly connected to the upper edge of the side wall of the foundation pit. In this way, the two measuring ends of the displacement sensor can be respectively fixed with the two ends of the spring to achieve the purpose of measuring the amount of spring expansion and contraction.

Further, the displacement sensor of the present invention comprises a magnetostrictive displacement sensor, a rod-type linear displacement sensor and a capacitive displacement sensor.

The magnetostrictive sensor has high precision and can withstand high temperature, high pressure and strong vibration; it has no wear and has good stability. The rod-type linear displacement sensor has small volume, convenient installation, diversified output signals, high precision and fast response. Capacitive linear displacement sensor has simple structure, high temperature resistance, radiation resistance, high resolution, good dynamic response and low cost. Through experiments, the above three displacement sensors are applied to the measurement system for accurate measurement and measurement of vertical displacement, convenient installation and strong adaptability.

The invention also provides a measuring method for the above-mentioned foundation pit deformation measuring system, which comprises real-time monitoring the angle value θ measured by the tilt sensor and the displacement value d measured by the displacement sensor, and according to the measured angle value θ and the displacement The value d determines the horizontal displacement X, the vertical displacement Y and the integrated displacement L of the foundation pit, and the specific determination method is:

If the angle value θ ≠ 0, the displacement value d ≥ 0, it is determined that the base pit only has a horizontal displacement X, X = 2πh * θ / 360 ° or X = h * tan θ, where h is the initial pit depth;

If the angle value θ = 0, the displacement value d ≠ 0, it is determined that the pit only has a vertical displacement Y, Y = d;

If the angle value θ ≠ 0 and the displacement value d < 0, it is determined that both the horizontal displacement X and the vertical displacement Y occur in the foundation pit, and the horizontal displacement X = 2π (hd) * θ / 360 °, the vertical displacement Y =d, the integrated displacement L = h ² + (hd) ^{2 -} 2h * (hd) * cos θ, where h is the initial pit depth.

If the angle value θ ≠ 0 and the displacement value d ≥ 0, it is determined that only the horizontal displacement X occurs in the foundation pit, because when the foundation pit only has a horizontal displacement, the upper edge of the sidewall of the foundation pit will drive the horizontal displacement of the wire tip, and the steel wire bottom The end is fixed, so the steel wire will deflect relative to the vertical direction, and the angle displayed by the tilt sensor is the rotation angle θ. The wire deflection process can produce very small stretches that are negligible (d ≥ 0). Since the horizontal displacement is very small compared to the pit depth h, the horizontal displacement can be approximated by the arc length formula X=2πh*θ/360°. The horizontal displacement can also be approximated by the sine formula X = h * tan θ.

When the vertical displacement of the foundation pit (base pit settlement), the deformation of the steel wire and the spring in the vertical direction will be concentrated in the spring portion, so the displacement of the spring can be measured by the displacement sensor to obtain the vertical displacement of the foundation pit. If the angle value θ=0, the displacement value d≠0, it is determined that only the vertical displacement of the foundation pit occurs, and the displacement of the spring is measured by the displacement sensor, and the vertical displacement of the foundation pit is obtained, Y=d=d; Measured value.

If the angle value θ ≠ 0 and the displacement value d < 0, it is determined that both the horizontal displacement X and the vertical displacement Y occur in the foundation pit. The horizontal displacement X of the foundation pit is obtained by the arc length formula, X = 2π(h - d) * θ / 360 °, and the vertical displacement Y = d, where h is the initial pit depth.

The integrated displacement L of the foundation pit is measured by the cosine formula, and the integrated bit L = h ² + (hd) ^{2 -} 2h * (hd) * cos θ, where h is the initial pit depth.

After calculation, the inclination sensor with an accuracy of 0.01° is used. When the depth of the foundation pit is 15 meters, the measurement accuracy of the above two measurement methods on the horizontal displacement is about 2.5 mm. The warning value required for the detection of the 15-meter foundation pit in the project is 3mm. Therefore, the measurement system and measurement method are in full compliance with the foundation pit measurement requirements. The measurement accuracy of the vertical displacement depends on the displacement sensor and can be selected as needed.

Third, by using the inclination sensor and the displacement sensor, the three displacements of horizontal, vertical and oblique can be measured in real time, and the displacement type and displacement data can be determined according to the measurement data, and the deformation amount of the foundation pit in all directions can be comprehensively determined.

Fourth, the measurement system and measurement method can replace the existing total station and other measurement methods, and the detection accuracy is high.

5. Each deformation measurement department of the whole measurement system can be flexibly controlled according to the actual measurement requirements of the foundation pit.

Further, the base pit deformation measuring system of the present invention further includes a data transmission portion and a data processing portion, the data transmission portion including an RFID chip and a microprocessor electrically connected to each of the sensor modules, and an RFID that wirelessly reads the RFID chip data. The reader/writer; the RFID reader/writer transmits the read data to the data processing unit, and the data processing unit calculates the amount of deformation of the foundation pit measured by each deformation measuring unit based on the data transmitted from the RFID reader/writer.

In this way, not only the deformation of the foundation pit of the plurality of pit deformation measurement points can be monitored at the same time, but also the RFID radio frequency technology has low cost and low energy consumption, and the RFID chip can be easily determined by the data stored by the RFID chip and its own serial number. The corresponding amount of deformation of the foundation pit at the measurement point of the foundation pit deformation. The above method does not require the staff to observe the data obtained by the sensor module one by one, which reduces the work intensity and labor cost of the staff and improves the work efficiency.

Further, the base pit deformation measuring system of the present invention further includes an integrated control unit connected to the remote control center, and the integrated control unit summarizes all the base pit deformation amount data calculated by the data processing unit and can transmit and read to the RFID reader/writer. instruction.

In this way, after the system is installed, all operations are completed through the remote control center, and no manual installation is required for each measurement, which reduces the work intensity of the staff, reduces the cost, improves the work efficiency, and does not require data collection. The sensor module, the data transmission part, and the data processing part of the front end deformation measurement unit are all in a "sleep" state, which does not waste power, and can ensure long-term operation of the system without frequent manual and manual maintenance.

DRAWINGS

FIG. 1 is a schematic diagram of the overall structure of an embodiment of the present invention.

2 is a schematic structural view of a deformation measuring unit according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing the principle of calculating the horizontal displacement X of the foundation pit according to the embodiment of the present invention.

FIG. 4 is a schematic diagram showing the principle of calculating the horizontal displacement X of the foundation pit according to the second embodiment of the present invention.

FIG. 5 is a schematic diagram of an overall structure of a third embodiment of the present invention.

FIG. 6 is a schematic structural diagram of a deformation measuring unit according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram showing the principle of measuring the vertical displacement Y of the foundation pit according to the third embodiment of the present invention.

FIG. 8 is a schematic diagram showing the principle of calculating the horizontal displacement X and the vertical displacement Y of the foundation pit according to the third embodiment of the present invention.

FIG. 9 is a schematic diagram showing the principle of measuring the integrated displacement L of the foundation pit according to the third embodiment of the present invention.

In the figure, 1.4 denotes an upper fixing plate, 1.5 denotes a lower fixing plate, and M denotes a side wall of the foundation pit.

detailed description

Embodiment 1

1 shows a foundation pit deformation measuring system including a deformation measuring portion 1.0 of a measured measuring point base deformation amount disposed at each base pit deformation measuring point, and the structural feature is as follows: The deformation measuring portion 1.0 includes a wire 1.1 and a sensor module 1.2. The bottom end of the wire 1.1 is fixed to the bottom of the pit near the sidewall of the pit, and the top end of the wire 1.1 is fixedly connected to the upper edge of the sidewall of the pit; the sensor module 1.2 includes The inclination sensor 1.2a for measuring the inclination angle of the steel wire 1.1; before the start of measurement, the deformation measuring portion 1.0 is installed; at the time of installation, the steel wire 1.1 is pre-tensioned, and the steel wire 1.1 is placed in a vertically stretched state.

The pit deformation measurement system in this example further includes a data transmission section 2.0 and a data processing section 3.0, the data transmission section 2.0 including an RFID chip 2.1 and a microprocessor 2.2 electrically connected to each sensor module 1.2 and wireless reading The RFID chip reader 2.1 data RFID reader/writer 2.3; the RFID reader/writer 2.3 transmits the read data to the data processing unit 3.0, and the data processing unit 3.0 calculates each deformation measurement based on the data transmitted from the RFID reader/writer 2.3. The amount of deformation of the foundation pit measured in Section 1.0

In this example, in order to achieve a fixed connection between the top end of the steel wire 1.1 and the upper edge of the side wall of the foundation pit, the upper fixing side plate of the side wall of the foundation pit is provided with an upper fixing plate 1.4 perpendicular to the side wall of the foundation pit, the top end of the steel wire 1.1 and the upper fixing plate 1.4 Surface fixed link.

In this example, the tilt sensor 1.2a is fixed to the top end of the wire 1.1.

In this example, the measurement method of the foundation pit deformation measurement system is to monitor the angle value θ measured by the inclination sensor 1.2a in real time, and determine the horizontal displacement X of the foundation pit according to the measured angle value θ, X=2πh*θ/360°. Where h is the initial pit depth.

Fig. 3 is a schematic view showing the principle of measuring the horizontal displacement X of the foundation pit by the above measuring method. As shown in the figure, in the initial state, the top end of the wire 1.1 is fixed at the p point of the upper edge of the side wall of the pit, and the bottom of the wire 1.1 is fixed at the point o, where op=h, h is the initial depth of the pit. When the foundation pit is horizontally displaced, the upper edge of the side wall of the foundation pit will drive the horizontal displacement of the top end of the steel wire 1.1, the top end of the steel wire 1.1 moves to the q point, and the bottom end of the steel wire 1.1 is fixed, so the steel wire 1.1 will deflect relative to the vertical direction. The angle displayed by the tilt sensor 1.2a is the deflection angle θ. Since the horizontal displacement is very small compared to the initial pit depth h, the horizontal displacement can be approximated by the arc length formula X=2πh*θ/360°.

Embodiment 2

The foundation pit deformation measuring system of this example is the same as that of the first embodiment, and the measuring method of the foundation pit deformation measuring system is different from that of the first embodiment. In this example, the measurement method of the foundation pit deformation measurement system is to monitor the angle value θ measured by the inclination sensor 1.2a in real time, and determine the horizontal displacement X, X=h*tanθ of the foundation pit according to the measured angle value θ, wherein h is the initial pit depth.

Fig. 4 is a schematic view showing the principle of measuring the horizontal displacement X of the foundation pit by the above measuring method. As shown in the figure, in the initial state, the top end of the wire 1.1 is fixed at the p point of the upper edge of the side wall of the pit, and the bottom of the wire 1.1 is fixed at the point o, where op=h, h is the initial depth of the pit. When the foundation pit is horizontally displaced, the upper edge of the side wall of the foundation pit will drive the horizontal displacement of the top end of the steel wire 1.1, the top end of the steel wire 1.1 moves to the q point, and the bottom end of the steel wire 1.1 is fixed, so the steel wire 1.1 will deflect relative to the vertical direction. (The wire 1.1 is stretched), and the angle indicated by the inclination sensor 1.2a is the deflection angle θ. As shown in Fig. 4, the horizontal displacement is approximated by the sine formula X = h * tan θ.

Embodiment 3

FIG. 5 shows a foundation pit deformation measuring system including a deformation measuring portion 1.0 of a measured measuring point base deformation amount disposed at each base pit deformation measuring point, and its structural characteristics are as shown in FIG. 6 and FIG. As shown in a partially enlarged view, the deformation measuring portion 1.0 comprises a spring 1.3, a wire 1.1 and a sensor module 1.2, the sensor module 1.2 comprising a tilt sensor 1.2a for measuring the tilt angle of the wire 1.1 and a measuring amount of the spring 1.3. Displacement sensor 1.2b; the bottom end of the steel wire 1.1 is fixed to the bottom of the foundation pit near the side wall of the foundation pit, the top end of the steel wire 1.1 is connected to one end of the spring 1.3, and the other end of the spring 1.3 is fixedly connected with the upper edge of the side wall of the foundation pit; Before the start, the deformation measuring portion 1.0 is installed; when installing, the spring 1.3 and the steel wire 1.1 are pre-tensioned, and the steel wire 1.1 and the spring 1.3 are in a vertically stretched state;

In order to realize the fixing of the spring 1.3 and the displacement sensor 1.2b, the upper fixing side plate of the side wall of the foundation pit is provided with an upper fixing plate 1.4 perpendicular to the side wall of the foundation pit, and the top end of the steel wire 1.1 is further provided with a lower fixing plate 1.5, and one end of the displacement sensor 1.2b is The lower surface of the upper fixing plate 1.4 is connected, the other end is connected to the upper surface of the lower fixing plate 1.5, and the displacement sensor 1.2b is connected in parallel with the spring 1.3 and in parallel.

In this example, the spring 1.3 has a spring constant of 0.5 to 2 N/mm. In this example, the size of the spring 1.3 is 8 mm in outer diameter, 30 mm in length, and 1 mm in thickness of the spring wire.

The displacement sensor 1.2b in this example measures the amount of expansion and contraction of the spring 1.3. The displacement sensor 1.2b is connected in parallel with the spring 1.3. One end of the displacement sensor 1.2b is connected to the top end of the steel wire 1.1, and the other end is fixed to the upper edge of the side wall of the pit. connection.

The displacement sensor 1.2b in this example includes a magnetostrictive displacement sensor, a rod-type linear displacement sensor, and a capacitive displacement sensor.

The pit deformation measurement system in this example further includes a data transmission section 2.0 and a data processing section 3.0, the data transmission section 2.0 including an RFID chip 2.1 and a microprocessor 2.2 electrically connected to each sensor module 1.2 and wireless reading The RFID chip reader 2.1 data RFID reader/writer 2.3; the RFID reader/writer 2.3 transmits the read data to the data processing unit 3.0, and the data processing unit 3.0 calculates each deformation measurement based on the data transmitted from the RFID reader/writer 2.3. The amount of deformation of the foundation pit measured in Section 1.0.

The base pit deformation measuring system in this example further includes an integrated control unit 4.0 connected to the remote control center, and the integrated control unit 4.0 summarizes all the base pit deformation amount data calculated by the data processing unit 3.0 and can be directed to the RFID reader/writer 2.3. Send a read command.

The measuring method of the base pit deformation measuring system described above is to monitor the angle value θ measured by the tilt sensor 1.2a and the displacement value d measured by the displacement sensor 1.2b in real time, and according to the measured angle value θ and the displacement value. d Determine the horizontal displacement X, the vertical displacement Y and the comprehensive displacement L of the foundation pit, and the specific determination method is:

If the angle value θ ≠ 0, the displacement value d ≥ 0, it is determined that the base pit only has a horizontal displacement X, X = 2πh * θ / 360 °, where h is the initial pit depth;

7 to 9 are schematic diagrams showing the principle of measuring the horizontal displacement X, the vertical displacement Y and the integrated displacement of the foundation pit by the above two measurement methods. In the initial state, the top end of the wire 1.1 is fixed by the spring 1.3 at the point p of the upper edge of the side wall of the pit, and the bottom of the wire 1.1 is fixed at the point o; at this time, op=h, h is the initial depth of the pit.

If the angle value θ ≠ 0 and the displacement value d ≥ 0, it is determined that only the horizontal displacement X occurs in the foundation pit, because when the foundation pit only has horizontal displacement, the upper edge of the sidewall of the foundation pit will drive the horizontal displacement of the top end of the steel wire 1.1, the steel wire 1.1 The tip moves to the q point, and the bottom end of the wire 1.1 is fixed, so the wire 1.1 is deflected relative to the vertical direction, and the angle indicated by the tilt sensor 1.2a is the deflection angle θ. The deflection of the wire 1.1 may result in very slight stretching, negligible (d ≥ 0). Since the horizontal displacement is very small compared to the pit depth h, the horizontal displacement can be approximated by the arc length formula X=2πh*θ/360°. The horizontal displacement can also be approximated by the sine formula X = h * tan θ. For details, refer to the principles of measuring the horizontal displacement X in the first embodiment and the second embodiment.

When the vertical displacement of the foundation pit (base subsidence) occurs, the deformation of the steel wire 1.1 and the spring 1.3 as a whole in the vertical direction will concentrate on the spring portion 1.3, so the amount of expansion and contraction of the spring 1.3 is measured by the displacement sensor 1.2b, and the foundation pit can be obtained. Vertical displacement. As shown in Fig. 7, if the angle value θ = 0 and the displacement value d ≠ 0, it is determined that only the vertical displacement of the foundation pit occurs, and the amount of expansion and contraction of the spring 1.3 is measured by the displacement sensor 1.2b, and the vertical displacement Y of the foundation pit can be obtained. , Y=d; d is the measured value of the displacement sensor 1.2b.

If the angle value θ ≠ 0 and the displacement value d < 0, it is determined that both the horizontal displacement X and the vertical displacement Y occur in the foundation pit. The vertical displacement of the top end of the steel wire 1.1 is approximately the spring expansion and contraction d measured by the displacement sensor 1.2b, that is, the deflection of the steel wire 1.1 is ignored. The length of the steel wire 1.1 after the deformation of the foundation pit is approximately the depth after the deformation of the foundation pit, and the vertical direction of the foundation pit The displacement Y≈d, combined with the vertical displacement of the foundation pit, as shown in Fig. 8, the horizontal displacement X of the foundation pit can be obtained by the arc length formula, X = 2π(hd) * θ / 360 °.

The comprehensive displacement L measurement of the foundation pit is shown in Fig. 9. Through the cosine formula, the integrated bit L = h ² + (hd) ^{2 -} 2h * (hd) * cos θ, where h is the initial pit depth.

The foundation pit project generally needs to be used for two years. It is measured at least once a week with the total station, and it requires two people to cooperate. Each measurement takes nearly 2 hours, and the workload is very large; the price of the total station is generally around 450,000. In the measurement system in this example, a set price (calculated according to 30 deformation measurement departments) is less than 30,000 yuan, and in this case, the measurement system can control the measurement remotely, and no need for the staff to be present, which greatly saves labor costs.

Claims

A foundation pit deformation measuring system includes a deformation measuring portion (1.0) disposed at a measuring point of each base pit deformation measuring point for measuring a base pit deformation amount, wherein the deformation measuring portion (1.0) includes a steel wire (1.1) And the sensor module (1.2), the bottom end of the steel wire (1.1) is fixed to the bottom of the foundation pit near the side wall of the foundation pit, and the top end of the steel wire (1.1) is fixedly connected with the upper edge of the side wall of the foundation pit; the sensor module (1.2) ) includes a tilt sensor (1.2a) for measuring the tilt angle of the wire (1.1); before the measurement starts, the deformation measuring unit (1.0) is installed; when installing, the wire (1.1) is pre-tensioned and the wire is made (1.1) ) is in a vertical stretch state.
A foundation pit deformation measuring system comprising a deformation measuring portion (1.0) for measuring a deformation amount of a base of a measuring point at each base deformation detecting point, wherein the deformation measuring portion (1.0) includes a spring (1.3) ), wire (1.1) and sensor module (1.2), the sensor module (1.2) comprises a tilt sensor (1.2a) for measuring the tilt angle of the wire (1.1) and a displacement sensor for measuring the amount of spring (1.3) expansion and contraction (1.2b); the bottom end of the reinforcing bar (1.1) is fixed to the bottom of the foundation pit near the side wall of the foundation pit, the top end of the steel wire (1.1) is connected to one end of the spring (1.3), and the other end of the spring (1.3) and the side wall of the foundation pit Fixed connection at the upper edge; before the measurement starts, install the deformation measuring part (1.0); when installing, pre-tension the spring (1.3) and the wire (1.1) and make the wire (1.1) and the spring (1.3) vertical Straight stretched state.
A base pit deformation measuring system according to claim 1, wherein said spring (1.3) has a spring constant of 0.5 to 2 N/mm.
A foundation pit deformation measuring system according to claim 2, characterized in that: the displacement sensor (1.2b) measures the amount of expansion and contraction of the spring (1.3) in a specific manner: displacement sensor (1.2b) and spring (1.3) In parallel, the displacement sensor (1.2b) is connected at one end to the top end of the wire (1.1) and at the other end to the upper edge of the side wall of the pit.
A base pit deformation measuring system according to claim 2, wherein said displacement sensor (1.2b) comprises a magnetostrictive displacement sensor, a rod type linear displacement sensor and a capacitive displacement sensor.
A foundation pit deformation measuring system according to any one of claims 1 to 5, wherein said base pit deformation measuring system further comprises a data transmission portion (2.0) and a data processing portion (3.0), said data transmission Department (2.0) includes an RFID chip (2.1) and a microprocessor (2.2) electrically connected to each sensor module (1.2) and an RFID reader (2.3) for wirelessly reading RFID chip (2.1) data; the RFID The reader/writer (2.3) transmits the read data to the data processing unit (3.0), and the data processing unit (3.0) calculates the measured value of each deformation measuring unit (1.0) based on the data transmitted from the RFID reader/writer (2.3). The amount of deformation of the foundation pit obtained.
A foundation pit deformation measuring system according to claim 6, wherein said base pit deformation measuring system further comprises an integrated control unit (4.0) connected to the remote control center, said integrated control unit (4.0) All the base deformation amount data calculated by the data processing unit (3.0) and can send a read command to the RFID reader/writer (2.3).
A measuring method for a foundation pit deformation measuring system according to claim 1, characterized in that the angle value θ measured by the tilt sensor (1.2a) is monitored in real time, and the level of the pit is determined based on the measured angle value θ The displacement X, X = 2πh * θ / 360 °, where h is the initial pit depth.
A measuring method for a foundation pit deformation measuring system according to claim 1, characterized in that the angle value θ measured by the tilt sensor (1.2a) is monitored in real time, and the level of the pit is determined based on the measured angle value θ The displacement X, X = h * tan θ, where h is the initial pit depth.
A method for measuring a foundation pit deformation measuring system according to any one of claims 2 to 5, characterized in that: the angle value θ measured by the inclination sensor (1.2a) and the displacement sensor (1.2b) are measured in real time. The displacement value d, and the horizontal displacement X, the vertical displacement Y and the integrated displacement L of the foundation pit are determined according to the measured angle value θ and the displacement value d, and the specific determination method is:

If the angle value θ ≠ 0, the displacement value d ≥ 0, it is determined that the base pit only has a horizontal displacement X, X = 2πh * θ / 360 ° or X = h * tan θ, where h is the initial pit depth;

If the angle value θ = 0, the displacement value d ≠ 0, it is determined that the pit only has a vertical displacement Y, Y = d;

If the angle value θ ≠ 0 and the displacement value d < 0, it is determined that both the horizontal displacement X and the vertical displacement Y occur in the foundation pit, and the horizontal displacement X = 2π (hd) * θ / 360 °, the vertical displacement Y =d, the integrated displacement L = h 2 + (hd) 2 - 2h * (hd) * cos θ, where h is the initial pit depth.