Tilt Angle Sensor Picture Book 4_Bridge Construction

D. Bridge construction

By placing static levels and inclination sensors on the entire bridge, the settlement and inclination of the main body of the bridge are monitored respectively, and the settlement and angle data are monitored in real time through the master control computer and mobile phone. Provide early warning of on-site construction conditions, and use intelligent monitoring of sensors to minimize safety risks and hidden dangers in bridge construction.

Case 1: Dam tilt monitoring

The inclination monitoring of the dam uses fixed inclinometers with a range of ±30° and a sensitivity of ≤9″. The fixed inclinometers are arranged in the longitudinal direction of the dam in the concrete core wall and on the downstream side of the dam. A total of three sections are arranged, respectively. They are dam cross 0+021.00, dam cross 0+041.00, and dam cross 0+061.00. Fixed inclinometers are arranged at 5m intervals along the elevation direction of a section. All equipment installation elevations and pipe mouth elevations can be appropriately adjusted and made according to the site conditions. Accurate records. The dam body inclinometer tube and SC50 steel pipe work together as a signal cable protection tube. Each set of signal cables is combined with an SC50 protective steel pipe outside the dam body inclinometer tube. The number of signal cables and protective steel pipes can be determined according to actual occurrences. Adjust appropriately. Flat steel is used to reliably connect the protective steel pipe, data acquisition box shell and dam lightning protection grounding system. Both the flat steel and the protective steel pipe need to be hot-dip galvanized.

Case 2: Remote dynamic monitoring of tilt and settlement of urban and rural buildings using T7-C inclination angle

The houses built in China in the 1970s, 1980s and early 1990s have entered the middle and late stages of use. Increased safety hazards caused by aging components and inadequate maintenance, coupled with factors such as man-made demolition and modification during use and the natural environment, have increased the pressure on safe management of houses. At the same time, due to the influence of the "emphasis on construction and neglect of management" mentality, the management of in-use houses has been neglected for a long time. Information on the demolition and modification of the house, changes in use functions, disasters, and damage status are nowhere to be found, which brings troubles to the management of the house.

The existing Class C dilapidated buildings have certain utilization value, and most of them do not have the conditions to stop use or be completely demolished. Some Class C dilapidated buildings have complex usage environments and site conditions, making it difficult to implement reinforcement measures. Houses and residents' concern about the quality of their houses has always been a focus, especially during severe weather such as typhoons, strong winds, and heavy rains. The total number of Class C dilapidated buildings is large and scattered. It is very difficult to rely on the competent authorities or communities for daily inspections. There is also a lack of relevant professional knowledge and comprehensive research and judgment capabilities. It is imperative to establish a dynamic remote automatic monitoring system for dangerous buildings.

To implement dynamic monitoring, daily, weekly, monthly and other systems can be selected according to actual needs, so that monitoring of real-time dynamics and risk avoidance measures (organizing personnel to evacuate in advance in times of crisis) are well-founded. Through the dynamic remote automatic monitoring system, managers can clearly see the basic information of the house, real-time on-site monitoring data (house settlement, tilt, cracks, etc.) and risk avoidance suggestions.

The company's system is a high-rise building monitoring solution based on Beidou high-precision positioning technology: it can dynamically monitor the tilt and settlement of high-rise buildings in real time, and is compatible with traditional sensors such as levels, acceleration sensors, and inclinometers.

By installing inclination sensors on the four corners of hazardous houses (buildings), we can obtain the inclination data of the building; installing static levels at the foundation of the building to obtain the settlement data of the building; and installing seam meters at cracks in the wall. , obtain wall crack width data. All sensor data are regularly sent to the cloud server for storage through the GPRS wireless network of the wireless DTU control unit, and then the client summarizes and analyzes the data through remote monitoring software to obtain the changes in tilt, settlement, and defects of the building for dynamic identification.

1. Monitoring system module function: Authorized system users can provide online monitoring services 365*24 hours a year through the building tilt remote monitoring system center server and networking with the building’s wireless terminal module.

→ Real-time monitoring: The computer in the remote monitoring center regularly inspects various sensors on each building, and remotely transmits the data collected by the sensors to the backend data center wirelessly to achieve the purpose of active monitoring and real-time monitoring.

→ Timely alarm: Once the data collected by each sensor of the building is greater than the safe value, the background system will actively send alarm information. The alarm method supports the following multiple methods: computer system alarm, WeChat public account alarm to the mobile phone of the designated person in charge, etc. to ensure that maintenance personnel receive the information and handle it in a timely manner.

à Remote login: This system uses cloud platform data management technology. System maintenance personnel can log in to the monitoring system from any computer in China with Internet access to query the tilt indicators of the monitored building, and view equipment information anytime and anywhere.

à Hierarchical management: The monitoring system supports hierarchical management of users. The system can set up multiple users and different levels of management permissions to support users with different permissions to view and maintain their own devices. That is, the general administrator can manage all devices, while the bottom-level administrator can only view the devices within their own management area, which is great. Convenient device management.

→ Information query: The monitoring system supports real-time monitoring information query and historical monitoring information query. Provide scientific basis for managers to conduct systematic analysis of building safety conditions.

→ Remote management: Supports remote restart, remote upgrade, remote configuration and other functions of equipment, saving maintenance personnel time, reducing the workload of maintenance personnel repeatedly visiting the site, and also greatly saving maintenance costs.

→ Massive operation: This monitoring system supports thousands of sets of equipment running online at the same time. At the same time, system engineers will monitor the status of system operation in real time and make reasonable optimizations in a timely manner.

2. Monitoring system screen, sensor installation

Using GPS and DTU automatic real-time monitoring equipment, inclinometers, crack meters and other special monitoring equipment and real-time dynamic monitoring and management platforms, the data of D-level and Class I dangerous buildings is monitored every hour; the data of C-level and Class II dangerous buildings is monitored every two hours, such as Due to typhoons and weather changes, as well as government requirements, data can be monitored every 2 to 5 minutes for Class I dangerous buildings and Class II dangerous buildings, and technicians can be on duty remotely at the same time.

Case 3: Application of inclination sensor in inclination measurement of towers and buildings

The story of two iron balls landing at the same time tells us about the famous Leaning Tower of Pisa. It is located in the small town of Pisa, Italy. It is an ancient tower built of white marble. It was built in 1173 and is 79 meters high. The ruler has tilted many times since it was built, and ordinary people can detect it with just their eyes. We know that the tower body will tilt slightly when the tower or building is under construction or due to the influence of external factors for a long time. If the tilt is serious and reaches a certain angle, it will collapse.

To prevent and monitor the inclination of towers and buildings, we can install inclination sensors on the objects that need to be monitored. The 3D MEMS sensor technology of Maixinminwei inclination sensor, biaxial measurement, can measure the inclination angle of the top plane. It can detect the tilt status of the tower in real time by converting it into the tilt orientation of the tower. It can also be output to the display instrument in real time, and can even be connected to the PLC control system and system computer to not only measure the tilt angle of the building, but also An indispensable equipment to implement the tower tilt measurement system.

Maixinminwei sensors are produced using the original VTI production line in Finland. All products undergo strict zero point, sensitivity and temperature calibration, making them suitable for applications with relatively high accuracy requirements. All products are fully automatically produced in batches with good consistency. This product is a PCBA type inclination sensor that can be easily integrated into the customer's system.

Case 4: Analysis of anti-overturning monitoring of bridge erecting machines based on inclination sensors

As bridge erecting machines are used more and more frequently in railway construction, overturning accidents of bridge erecting machines occur from time to time. The anti-overturning device of the bridge erecting machine came into being. The device consists of two parts: the pathfinder wheel loading system and the monitoring and control system, and is installed in front of the bridge erecting machine.

The inclination sensor can detect at any time the longitudinal and transverse inclination angles of the pathfinding wheelset and bridge erecting machine frame caused by the subsidence of the roadbed. Under the action of the pathfinding wheelset, if the subsidence of the roadbed exceeds the specified value, or the inclination of the left and right tracks exceeds the specified value, the monitoring and control system will alarm in time, cut off the power of the drive motor, and use the braking system to make the frame Emergency braking of the bridge machine ensures that the bridge erecting machine does not enter unfavorable areas and prevents the bridge erecting machine from overturning.

Sensor H1 detects the lateral inclination of the tie rod between the left and right pathfinding wheels, indicating the lateral inclination of the line caused by uneven subsidence of the roadbed; sensor H2 detects the actual lateral inclination of the vehicle body; sensor L1 detects the actual longitudinal inclination of the vehicle body; sensor L2 detects the actual longitudinal inclination of the vehicle body; The longitudinal inclination angle of the lower arm of the overturning device; the difference between the longitudinal inclination angles measured by sensor L2 and sensor L1 represents the subsidence amount of the roadbed under the vertical load exerted by the pathfinder wheel loading system (compared with the subsidence of the roadbed caused by the wheel set of the bridge erecting machine). Equivalent in quantity), used to measure the compactness of the roadbed. Compare each of the above measured quantities with their respective thresholds determined through research to determine whether the compactness of the roadbed meets the requirements, that is, whether the bridge erecting machine can pass safely.

The T7000-A series dual-axis inclination sensors are based on MEMS technology. The products have analog output and digital output such as RS485, RS232, CAN, etc., and have high accuracy, vibration resistance and long-term stability. In the temperature range of -40 - 85°C, the zero point drift is less than 0.2°, the measurement range is 0 - ±90°, the nonlinearity is better than 0.01°, and the repeatability is excellent. Since the sensing unit adopts self-developed anti-vibration technology, it solves the problem of large data changes of the tilt sensor in a vibration environment. The module is not sensitive to vibration and can withstand impacts higher than 10,000g.

Case 5: Inclination sensor application in water conservancy and hydropower dam monitoring system

The safety of hydropower dams not only directly affects the efficiency of the power plant itself, but is also closely related to the lives and property of downstream people, national economic development and the ecological environment. With the development of electronic technology and the promotion and application of digital communication technology, monitoring automation has been provided. At present, the automation of dam monitoring in the national power system has been fully launched and is developing in the direction of networking and intelligence..

Main monitoring items and equipment:

1. Deformation monitoring

Dam deformation is an important monitoring item for hydropower station dams. It can be divided into two sub-items: horizontal displacement and vertical displacement. Most dams are equipped with horizontal and vertical displacement observation on the dam top, and usually one pair of measuring points is set up in each dam section. In recent years, more attention has been paid to the horizontal displacement observation of typical dam sections, and more than three measuring points are generally arranged along the dam height.

Dam deformation monitoring equipment can choose tensile wires, GPS, fixed inclinometers, inclinometers, static levels, etc.

2. Seepage

Dam seepage is also one of the important monitoring projects of hydropower station dams. It can be divided into two sub-items: seepage pressure and seepage volume. The observation facilities of the concrete dam are located in the foundation corridor, with one measuring point for each dam section for uplift pressure; the seepage flow measuring points are determined based on the water collection conditions of the drainage ditch, and generally the regional flow rate and total volume can be measured. The seepage flow of earth-rock dams is observed at the seepage collection point at the dam toe, and the seepage pressure measuring points are arranged below the wettability line of the dam body or behind the toe plate according to the specific dam type. In addition, groundwater level observation projects are also set up on the slopes on the left and right sides of the dam to monitor seepage around the dam.

The main detection equipment for dam seepage monitoring is piezometer.

3. Vipassana items such as stress and strain

Internal observation projects such as dam stress and strain are general observation projects for hydropower station dams. Only some important measurement points are included in automated monitoring. Many medium and low dams have stopped measuring or sealed such observation projects. Internal observation items such as stress and strain are commonly used in the dam construction stage. Commonly used monitoring equipment include embedded strain gauges, steel bar gauges, etc.

Case 6: Rail transit subgrade settlement monitoring solution

Solution applicable scenarios:

This solution mainly solves the problems of untimely collection of track environment monitoring data, lagging monitoring information, and difficulty in equipment management and line operation management.

This solution can be applied to:

1. Deformation monitoring and settlement monitoring of subway tunnel subgrade, railway subgrade and high-speed railway bridge subgrade during operation period

2. Deformation monitoring and settlement monitoring of railway subgrade when shield tunnels penetrate the surface

3. Deformation monitoring and settlement monitoring of high-speed railway bridge subgrade when shield tunnels penetrate the surface

4. Monitor deformation and settlement of surrounding large structures, highways/urban roads, bridges/culverts and other roadbeds during construction

5. Real-time monitoring can be carried out not only during the construction of rail transit line projects, but also during the post-construction line operation stage.

The entire solution takes the monitoring and early warning cloud service platform as the core, and uses the mobile Internet as the information transmission carrier to connect the real-time interaction of information between sensor equipment and users. This solution realizes the long-term and continuous collection and transmission of information reflecting the geotechnical safety status, changing characteristics and development trends of rail transit lines, and carries out the entire workflow of statistical analysis, information feedback, and safety warnings. Ensure that the technology is mature, the economy is reasonable, and the plan is reliable to ensure the safe operation of people, property, and transportation lines in the engineering structure and surrounding environment.

Scheme diagram:

This solution is an overall monitoring information solution, consisting of three parts: monitoring equipment, communication network, and monitoring and early warning cloud service platform.

Introduction to core monitoring equipment: T700-A

Monitoring items and monitoring instruments:

Railway line settlement observation

Implementation function:

1. 24-hour real-time monitoring: Through real-time online monitoring of supporting structures, surface settlement, inclination of retaining piles, etc., the structural changes of the building foundation pit can be grasped in real time.

2. Report push: Monitoring results are displayed and released in real time, and monitoring reports are pushed to users regularly.

3. Multiple graded early warning: Establish a three-level alarm mechanism. When abnormal data is detected, users will be notified immediately through SMS, fax, broadcast, etc., to achieve a comprehensive early warning function.

4. Emergency plan processing: directly extract corresponding processing methods from the expert system, and take timely measures such as personnel intervention and road blockade to eliminate potential safety hazards in the bud.

5. Structural trend analysis: Through monitoring data analysis and safety evaluation during the foundation pit construction period, structural stability trend analysis can be achieved.

6. Historical data storage: The storage of monitoring data provides an analogous basis for the design and construction of similar projects in the future.

Case 7: Automated monitoring of settlement inclinometer to ensure construction and operation of bridge foundation pits

solution

According to the conditions of the bridge and excavation of the foundation pit, we set up monitoring points on the bridge piers and beams. In order to ensure the smooth progress of the project construction, we communicated with the owner many times to design and optimize the construction plan, and independently developed an automated remote settlement system for tilt settlement of building structures. The monitoring system monitors the settlement and inclination of the main body of the bridge by installing static levels and inclination sensors on the entire bridge. It monitors settlement and angle data in real time through the main control computer and mobile phone, and provides early warning of on-site construction conditions. With the help of intelligent monitoring by sensors, Minimize safety risks and hidden dangers in bridge construction.

There are two GNSS monitoring stations arranged on the bridge part, namely GNSSA1 and GNSSA1 monitoring points on the main span 1/2.

The specific layout location is shown in the picture on the right:

Technical advantages

Maixinminwei automated building structure tilt and settlement remote monitoring system can accurately display the deformation of large bridges in real time. Over the years, we have gained market share and accumulated a lot of successful experience. This also promotes the scientific, informatization, standardization and visualization of large bridge structural health monitoring systems, effectively ensuring the safe operation of large bridges.