Geometry Assessment of Slip Surface of Bargijahan Trench to Design Appropriate Support System

Bargijahan trench whose height and slope angle were respectively designed 20 m and 80° located at the portal of Lavasan water conveyance tunnel. This trench which excavated in weak conglomerate zone is located in northeast of Tehran, Iran. Field observation demonstrated that this trench was potentially unstable; therefore, designing a support system to stabilize it was unavoidable. One of the most important factors to design support system is the geometry of slip surface. In this respect, first, a simple tool was built to monitor the direction (3D) and quantity of slope movement. This tool was installed on tension cracks at top of the slope. By monitoring the displacements using installed tools, the movement vector of slope was determined and it was confirmed that this trench rotated on its toe. Then, employing sensitivity analysis strategy, parameters of soil including, cohesion and friction angle were estimated. Finally, by creating a numerical model and according to determined geomechanical parameters, the slip surface geometry was sized up to efficiently design the support system.

کلیدواژه ها:

slope stability ، instrumentation and monitoring ، numerical modeling ، sensitivity analysis