三峡库区赵树岭滑坡稳定性物理模拟试验研究

PHYSICAL MODEL STUDIES ON STABILITY OF ZHAOSHULING LANDSLIDE IN AREA OF THREE GORGES RESERVOIR

采用3个小比例尺二维物理模型试验,对三峡库区赵树岭滑坡在库区蓄水、水位波动、地面荷载和可能的地震荷载作用下的整体稳定性及其可能的变形、破坏机理进行了研究。采用百分表、网格线和数码相机,对模型的变形和位移进行监测和记录。采用高容重和低容重模型材料,分别模拟地下水位以上和地下水位以下滑坡岩体;根据渗透理论和相似理论,解算水位骤降时模型条件下的动水压力合力矢量,采用施加集中力的方法模拟动水压力;地表建筑荷载采用重晶石–石膏块体模拟;地震荷载采用使模型倾斜的方法模拟。试验结果表明:未来三峡水库运营期间,不论库水位处于175m或145m,还是从175m骤降至145m,建有7层建筑物的该滑坡均整体稳定;而当地震震级大于某级时,该滑坡发生整体失稳,并且库水位从175m骤降至145m时,稳定性最差,其次是145m情况下,175m库水位时稳定性最好;如果发生整体滑坡事件,其滑坡机理为牵引式。

Three small-scale 2D physical model experiments were conducted on a model table with the goals of investigating the potential deformation features and failure mechanics of a landslide in the Three Gorges Reservoir under conditions of reservoir impounding, water level fluctuation, building load on the surface of slope and potential seismicity, and evaluating its whole stabilities in the future. Dial gauges, gridding lines and digital camera were used to monitor quantitatively and write down qualitatively the deformations and displacements of the models. High/low unit weight model materials were used to simulate self-weight of sliding mass above groundwater level and sliding mass below groundwater level respectively. According to seepage force theory and similarity laws, the resultant hydrodynamic force was obtained by concentrated loading. The loading owing to the buildings was simulated by some Barite-gypsum blocks placed on the surface of the model. The seismic loading was simulated by raising the inclined plane on which the landslide model was placed. The research results show the slope on which a seven-floor building locates was stable when the water level is 145 m or 175 m, or under a rapid drawdown condition from 175 m to 145 m. While the intensity of earthquake is greater than a certain value, it must be of instability; and its stability must be the worst when the water level in the reservoir drawdown rapidly from 175 m to 145 m; and its stability must be better under condition of the water level 175 m than that of the water level 145 m. If the landslide would happen, the failure mechanism must be pull-type.