Design of slope automatic monitoring scheme

Design of slope automatic monitoring scheme

- from the Shenzhen landslide site rescue automation monitoring

On December 20, 2015, Shenzhen Guangming new district slag field soil landslide caused significant losses, emergency rescue and disaster relief is still in progress. The government and relevant institutions and units have taken action to contribute to the disaster area. Artificial slope as a major source of risk, the public was impressed. The monitoring of non-slip residual body of artificial slope must be carried out in time to avoid secondary disasters.

Site profile

After comprehensive field survey of landslide residual body, the main situation is as follows:

1, landslide residual body range is large, west, south, east landslide surface total length of nearly 1.2 kilometers;

2. deformation cracks are common in the non-collapsed deposits outside the crater body, and the stability is poor;

3. the site near the original mountain at the upper part of the original collapse body is in a power-off state, and the communication network is poor;

4, mining face, traffic difficulties, is not conducive to large equipment approach.

conceptual design

According to the above site conditions, the principle of automatic monitoring is formulated as follows:

A, is beneficial to large-scale layout, is easy to arrange, is fast in speed, and can output data as soon as possible;

B to displacement monitoring is given priority to, rainfall, video as a supplement; The displacement of that whole reaction non-slip accumulation body;

C the monitoring mode requires less external conditions such as infrastructure and power supply;

Iii. programme implementation

Displacement monitoring

3.1.2 displacement monitoring equipment

Leica automatic measuring total station ( measuring robot ) is used as the data acquisition equipment for three-dimensional displacement monitoring. This type of equipment has stable and excellent performance, and is widely used in the safety monitoring of subway tunnels, hydropower dams, mine slopes and other high requirements.

3.1.3 axis design

The coordinate system is established by taking the east-west direction as the y axis and the north-south direction as the x axis. Because there is no local reference point survey, according to the site orientation brief judgment direction and taking into account the landslide main sliding direction, the landslide main sliding direction for the north to determine the site monitoring coordinate system.

3.1.4 monitoring diagram

3.1.6 layout of monitoring points

According to the three directions along the east, west and south according to the section layout, each section according to the scene set 2 - 3 prism, control point fixed in the mountain rock stability area, comprehensive reaction section deformation and crack change. ( omitted: layout of control points and monitoring points )

3.1.7 monitoring frequency

Each cycle observation time is completed within 30 minutes, observation once an hour, each time 2 back, each back to the left plate right observation. Increase monitoring frequency in special cases such as rain or landslide with accelerated subsidence.

3.2 video real-time monitoring

At the same time of strengthening the landslide displacement monitoring, image monitoring of residual body area, remote observation of residual body real-time trend. The night visual distance > 300 m, daytime visual distance > 500 m..

3.3 real - time monitoring of rainfall

Combined with the field survey results and the rain gauge installation site selection specification, and considering the installation and debugging difficulties, later maintenance difficulties and other factors, this scheme is selected to be placed near the displacement observation room, convenient for centralized management and maintenance, at the same time is located in the main monitoring area, is within the scope of mountain catchment.

Thoughts and experience sharing of slope automatic monitoring design;

Selection of surface displacement monitoring mode;

Three conventional methods of online automatic displacement monitoring: GNSS mode represented by Beidou, photoelectric measurement mode represented by measuring robot, and displacement sensor mode dominated by small deformation and relative displacement.

Gnss is not sensitive to the weather environment and is suitable for long-term monitoring. However, there are more requirements for power supply, communication and infrastructure, and the practical conditions such as urgent emergency rescue monitoring time, tight tasks and more monitoring points are not suitable for use;

The displacement sensor is mainly based on relative displacement, so it is necessary to customize the production according to the site, which is suitable for large deformation and difficult to select the reference position. The installation period is long, and is not suitable for the case of large deformation area, not considered in the early stage.

The photoelectric measurement method represented by the measuring robot has less requirements on the field infrastructure, power supply, communication and other conditions, is easy to quickly install and enable, and can start automatic data collection within one day at the earliest. And that monitor point is low in cost, simple to install and suitable for large-scale layout. Meanwhile, that monitor precision is high, and the displacement condition of the collapsed body can be fully reflect. In this scheme, the measurement robot is adopted for monitoring.

Rainfall and slope water level monitoring:

According to the field experience, slope rainfall monitoring is very necessary. Rainwater pressure is an important source of slope displacement. The difference between that locally measure rainfall and the weather forecast over a wide area is large, and the maximum difference can be up to two time. The local rainfall has a significant effect on the settlement and displacement of slope soil.

Deep displacement monitoring:

Deep displacement monitoring can understand the deep displacement of soil mass, and it is an important supplement to surface displacement. It can also be used as a design consideration for key monitoring projects. However, the current high cost of technical means is the main obstacle to its large-scale application. The mature application of new method and new technology in the future is expected to solve this problem step by step, so that the deep displacement monitoring becomes a regular item in slope monitoring.