Abstract:Based on the monitoring data of landslide deep deformation obtained with inclinometer,the original deformation mechanism for sliding zone of talus slide is studied. It is found that the deformation of landslide starts from the bottom wall(main sliding face of sliding zone),and the development of deformation is progressive from the bottom wall up to the top wall. It lasted respectively for about thirteen to twenty-eight months for different levels of sliding zone. The relation curves between deformation and time are divided into two types. The first has four stages:uniform velocity,increased velocity,decreased velocity,and constant deformation. The second has three stages except for the increased velocity stage. Different stages are related to excavation or reinforcement of landslide. According to the propagation character of deformation discovered recently,the safety forecast standard is proposed. The standard is corresponding to the beginning of deformation acceleration at top wall. It is very important for monitoring and controlling the safety of landslide.