The dam health monitoring plan - dam deformation monitoring, due to the complex construction period of the dam and the consideration of many factors, such as permeability, surrounding rocks or soil, frequency of earthquakes, whether natural disasters such as landslides and rockfalls often occur, etc. Tilt angle sensors have been widely used for dam deformation monitoring. Some of them are directly installed on the dam body itself, while others are installed in the dam or foundation structure to monitor small changes in the dam and surrounding environment in real time, such as water seepage, severe corrosion of surrounding rocks, earthquakes or landslides, and the impact of landslides on the nearby geological environment. Although the impact is sometimes very small, if the small impact is not dealt with in a timely manner, it may have serious consequences.
The WCIS300 series tilt sensors independently developed and produced by Weiqin Sensing can not only meet the needs of most structural health deformation monitoring, but also be used in special applications such as dam monitoring. It can record and display the angle changes of the dam structure in real time, and transmit the deformation angle values to the control system. The control system can provide prompts and alarms, so that the dam staff can timely know the alarm information and take corresponding actions.
II Monitoring content of slope detection system
Due to the gravity of the dam foundation, dam body, and upstream water storage, it may cause uneven settlement deformation of the dam, rotational deformation of the foundation and dam body, and distortion deformation of the dam body caused by changes in horizontal pressure and external temperature due to water storage. If these deformations are too large, they will seriously affect the stability and safety of the dam. Therefore, it is necessary to monitor the vertical and horizontal displacement of the dam, as well as the inclination of the dam body.
Monitor the magnitude and pattern of the deformation of the dam during construction and operation, and predict and forecast the deformation trend of the dam based on the deformation amount, in order to ensure the quality and safety of dam construction and operation. The content of deformation monitoring for reservoir dams mainly includes monitoring the horizontal displacement and vertical displacement of the dam top and bottom, as well as detecting the slope of the dam
1. Vertical activity tilt detection
The vertical displacement changes of monitoring points caused by the gravity of the dam foundation, dam body, and upstream water body are detected by installing conduits to place inclination sensors. When the inclination changes occur, the inclination angle of the horizontal nodes can be measured by the inclination sensors.
The inclination sensor can be installed as a measuring unit to work independently, or multiple connecting points can be installed to measure the inclination of each section of the measured structure, in order to describe the deformation curve of the structure. If the measured object is mounted in a two-dimensional direction, the two-dimensional deformation of the structure can be measured. The inclination sensor can be recycled and reused, making it convenient for long-term health monitoring of dams.
2. Horizontal activity tilt detection
Under the condition of an empty reservoir, the dam of a hydropower station may tilt upstream due to the influence of the gravity of the dam body. After being filled with water, it may tilt downstream due to the thrust of the reservoir water. The magnitude of its inclination has a significant impact on the stability of the dam body. By connecting the horizontal displacements of various elevation measurement points along the river on the same vertical line into one line, the angle between this line and the vertical plane of the left and right banks is the inclination angle of the dam body in the vertical direction; By connecting the vertical displacement of each measuring point of the static level system along the river in the dam foundation corridor into one line, the angle between this line and the horizontal plane is the horizontal inclination angle of the dam body.
3. Monitoring of slope inclination of dam body
The slope inclination of the dam is affected by both the vertical settlement and horizontal direction of the dam, resulting in a certain degree of slope inclination. We monitor the slope inclination state through inclination sensors, providing reliable basis for analyzing the overall operation of the dam.
III Constructing a Dam Attitude Monitoring System Using Weiqin Sensing WCIS300 Series Tilt Sensor
The monitoring of the entire dam system includes monitoring of the overall tilt posture of the dam: horizontal displacement monitoring, vertical settlement monitoring, slope (dam slope) tilt monitoring. Fixed vertical sensors are used for horizontal displacement monitoring, and sensor strings are placed through vertical conduits on the inclined dam body. Fixed horizontal inclinometers are used for vertical settlement, and WCIS300 series tilt sensors are placed at the predicted tilt points for slope monitoring.
Adopting a centralized data processing approach, the sensor strings are connected to the data acquisition system, and after a long period of data collection, alarms can be triggered based on a certain rate of change or other standards. Through data analysis, the horizontal displacement and vertical settlement of the dam body over a certain period of time can be determined. Combined with slope inclination analysis, a more detailed attitude of the current dam can be obtained.
1. Use WCIS300 series angle sensors to monitor the horizontal displacement of dams
Contains a certain number of fixed inclination sensors installed in the inclinometer tube, which provides a channel for measuring below ground level. The guide groove inside the inclinometer tube controls the direction of the inclination sensor. The inclinometer tube is installed in a vertical borehole that passes through an area in the formation where displacement movement may occur. A set of guide slots needs to be aligned in the expected displacement direction.
For example, for tunnels excavated downwards or towards the mountain, the inclination sensor is fixed inside the inclinometer tube and spans the displacement activity area. When the formation undergoes displacement, the inclinometer tube produces displacement, causing the sensors installed inside the tube to tilt. The inclination of the measuring sensor can obtain the displacement profile of the inclinometer tube. The measurement length of each sensor is displayed in millimeters, and the cumulative displacement of the entire series of sensors is also displayed in millimeters.
2. Use WCIS300 series angle sensors to monitor vertical settlement of dams
Includes a certain number of fixed inclination sensors installed in the inclinometer tube. The inclinometer tube provides a channel for measuring below ground level. The guide groove inside the inclinometer tube controls the direction of the sensor. The inclinometer tube is installed in a horizontal borehole that passes through an area in the formation where displacement movement may occur. A set of guide slots needs to be aligned in the expected displacement direction.
3. Use WCIS300 series
Relying solely on horizontal or vertical inclinometers cannot comprehensively consider the impact of these two types of dam body movements on the overall slope of the dam. The use of angle sensors can comprehensively estimate the simultaneous effects of horizontal and vertical displacements on the dam slope.
