Abstract:

Two serious deformations occurred in the Wangxia unstable rock mass in Wushan County in the Three Gorges Reservoir in 2010 and 2011，but after geological surveying, monitoring-scheme designing, monitoring-data processing and macroscopic phenomena analyzing, these collapse deformations were successfully forecasted through long-term monitoring rock masses by total station, crack displacement meter, GPS, etc.,avoiding heavy casualties. The deformations of the unstable rock mass contain two types of gradual change and mutation.It should adopt corresponding monitoring methods and frequencies in different deformation stages based on geological survey, and the key parts of the unstable rock masss hould be monitored. The monitoring data should be analyzed with close combination of the macro phenomena, and the deformation trend should be grasped from the rear, precipice and cliff bottom of the rock mass. The monitoring scheme of unstable rock masses should observe the five principles, which are detail investigation, careful deployment, phenomenon observation, grasping trend and accurate prediction, ie. Wangxia Experience. This experience can provide the reference for monitoring unstable rock masses.

Key words: Wangxia unstable rock mass, deformation failure, geological characteristic, deformation monitoring, danger forecast