不同降雨模式下膨胀岩边坡模型试验研究

采用原状膨胀岩进行室内边坡模型试验，研究膨胀岩边坡在连续降雨和湿-干循环模式下的变形和水分入渗特性，揭示两种模式下膨胀岩边坡的变形破坏模式。试验发现，连续降雨模式下初期数次降雨对膨胀岩边坡变形影响最大，有明显的水平方向位移，后期变形很小且趋向稳定。湿-干循环模式下边坡膨胀变形及深部岩体含水率降雨完成后一段时间才达到峰值，随循环次数及降雨量增大，边坡变形速率及变形量都明显增大，岩体裂隙不断发育，水分入渗深度增大，但限于表面一定深度，对深部岩体影响较小。试验结果对工程应用有一定的指导意义：连续降雨模式初期膨胀较大，须加强和完善初期的排水措施，做好边坡的支挡防护措施；湿-干循环模式下，随循环次数增加，做好坡面的防护措施，以起到保湿防渗作用；两种降雨模式均说明纯膨胀性泥岩边坡不发生典型的圆弧滑动等破坏模式，而工程边坡的滑动多发生在软弱夹层上，因此，要做好该类边坡的软弱夹层特性勘察，对于不含软弱夹层的纯泥岩边坡要重点监测其浅层变形特性。

Model test study of expansive rock slope under different types of precipitation

The indoor slope model tests were conducted to investigate the deformation, water infiltration and failure characteristics of an expansive rock slope under different types of precipitation. Significant horizontal displacement was found under the initial rainfall in continuous rainfall mode, whereas the later deformation was small and tended to be stable. The peak values of displacement and deep rock moisture content were reached at a period of time after rainfall ceased. With the increase of cycle number and rainfall, the slope deformation and the deformation rate increased significantly, and the rock fissures developed further, resulting in an increase in water infiltration depth. This was observed in the soil layer close to the ground surface, but not in the deep rock. The experimental results imply that, due to initial large swelling-induced deformation in the continuous rainfall mode, the drainage and protective measures should be enforced and improved; in the wet-dry cycles mode, the anti-seepage measures for slope surface should be improved to resist the infiltration of rain with the increase of cycle number. In additional, the typical circular sliding failure of purely expansive rock slope was not found in aforementioned two rainfall modes in the tests. However, the engineering slope failure often occurs in the weak interlayer. Therefore, further investigation into the weak interlayer in expansive rock slope should be conducted , and for the mudstone slope without weak interlayer, more attention should be paid to monitoring the shallow deformation characteristics.