STUDY ON THE UPLIFT MECHANISM OF THE DAM BODY AND ROCK MASSES ON RIGHT SIDE OF TONGJIEZI DAM AFTER WATER IMPOUNDING USING A COUPLED HYDRO-MECHANICAL MODEL, SICHUN PROVINCE, CHINA

摘要

During filling of the Tongjiezi reservoir, a multi-purpose project in Sichuan Province of China, it was found that the dam body and the rock masses on right side of the valley were uplifted obviously, with a measured maximum uplift of 22.2mm and 24.3mm respectively. And after the reservoir impounding, up to the present from 1993, though the added uplift was markedly decreased, the trend of uplift did not cease, with measured maximum uplift from 22.2mm to 27.5mm in dam body and from 24.3mm to 28.9mm in rock mass. This rare phenomenon caused concerns from various parties. In this paper, based on geomechanics and comprehensive study of the geological background of the dam site and observed data, a coupled hydro-mechanical model was presented to describe the uplift process. It is concluded that, combined with the special hydrogeological and engineering geological conditions of Tongjiezi dam site, the hydro-mechanical coupling after the reservoir impounding is the main factor contributing to the uplift, and the time-dependent deformation is due to rheological behavior of rock mass under the seepage pressure.