Comprehensive Assessment on Earthquake Disaster Temporal Deterioration
Mechanism of a Reservoir Collapse-slide Slope
REN Dong-wei ZENG Liang-liang ZHANG Hong LI Chang-tao
Yunnan Constructions Investment Group Highway Construction Co.Ltd.
Ascertaining slope disturbance deterioration mechanism of reservoir slope in high seismic region under earthquake, reservoir water and human engineering activities actions is the key point of stability estimation and premise of scientific reasonable countermeasures done. Relying on a reservoir collapse-slide slope, its main disaster-causing factor, slope body disturbance and stability deterioration mechanism are discussed with surface survey and numerical computing combined on basis of survey and design services, water storage and landslide bulletins of three gorge immigration bureau, correspondence of participating units and historical earthquake recording. And feasibility of engineering disposal is comprehensively estimated, too. Main conclusions are as following. (1) Engineering construction does little effect on the reservoir slope’s body disturbance and stability. Yongshan earthquake and Ludian earthquake both affect the slope. But Ludian one with 1339 times aftershock does more harm to slope body and remarkable loosening effect produced. High water level enhances shock loosening rock mass saturated softening. The whole slope stability is basic-to-not stable, front local stability being not-to-losing stable. (2) Deformation traces on slope top and surface are historical ones, which don’t expand. But unstable evidences in front of slope is fresh ones, which have threated bridge foundations safety. (3) Limit equilibrium method results present slope at survey stage being stable, slope after two earthquake records being basic stable and not stable. To meet 1.30 safety standardization needs strength force being 20015kN/m~197421kN/m, reinforcement depth being 60~180m and reinforcement scope being 350m~980m. It is difficult to meet reinforcement aim by engineering measures. (4) The reservoir slope is estimated comprehensively, whose whole stability being basic-to-not stable, that of local one being not-to-losing stable, which deformation scope being deep and wide. Because it is hard to reinforce by regular engineering measures, so the building bridge is suggested to be rejected. These conclusions can be referred by similar project and used in reservoir management.