不同降雨条件下顺层边坡力学响应模型试验研究

 为研究降雨条件对顺层边坡坡体内部力学响应特征的影响，结合叠加喷洒降雨技术和光纤光栅监测技术，开展不同降雨类型及支护条件下顺层边坡的地质力学模型试验，分析雨水入渗对于坡体位移、孔压力以及支护结构受力的影响等。试验结果表明，对于无支护边坡，在短时间暴雨条件下，位移和孔压力变化主要发生在降雨期间的坡体表层附近，坡体表层前端处雨后位移的增幅较大且孔压力的消散较快，坡体稳定性的主要影响因素是超孔压的累聚和消散；在长时间小雨条件下，位移和孔压力的影响范围逐渐向深部扩展，雨后位移仍保持较大的增长速率但孔压力消散较慢，坡体稳定性的主要影响因素是雨水入渗软化软弱夹层。相对于无支护边坡，有支护边坡的坡体位移和孔压力均显著减小，这主要是由于支护结构的施加限制坡体表面裂缝的扩展，从而减弱雨水的入渗，在总降雨量相同的情况下，短时间暴雨条件时支护结构的受力较快达到稳定，长时间小雨条件下支护结构的受力调整的速率较慢，在降雨试验结束6 h后，坡体前端推力最大值出现的位置不同，前者最大值出现在顶层，后者最大值出现在中层，且后者相应位置处的数值是前者的1.5～1.7倍。试验成果对于类似边坡工程的施工设计及加固维护具有参考意义。

MODEL TESTS FOR MECHANICAL RESPONSE OF BEDDING ROCK SLOPE UNDER DIFFERENT RAINFALL CONDITIONS

The rain spraying and fiber grating monitoring were used in a geomechanical modeling test under different rainfall and support conditions to investigate the mechanical influences of different rainfall conditions on the bedding rock slope. The physical data including the displacements，the pore pressures and the supporting structure?s internal forces were analyzed. It was found that the displacement and the pore pressure variations occurred mainly at the surface of slope for the unsupported slope under the heavy rainfall condition within a short time，while the displacements became larger and the pore pressure dissipated faster in the front of the slope surface after the rain. The accumulation and dissipation of excess pore water pressure were the main factors influencing the slope stability for this type of slope. For the unsupported slope under light rainfall during a long period，the displacements and pore water pressures also occurred beneath the slope surface. A large growth rate of displacements and a smaller decreasing rate of pore water pressure dissipation remained after the rain. The soften effect on interlayers due to rain infiltration may be the main influential factors to affect the slope stability in this case. While in the case of the supported slope, the displacements and the pore pressures were much smaller due to the restriction on the crack development which reduced the rain infiltration. The stresses of the supporting structure reached stable values quickly under the heavy rainfall condition within a short period and are adjusted slowly under the light rainfall condition within a long period. The maximum values of slope thrust 6 hours after the raining appeared in the different positions at different rainfall conditions. The maximum value occurred at the top of the supporting structure under the short and heavy rainfall condition and occurred at the middle of the supporting structure under the long and light rainfall condition. The magnitude of the latter was about 1.5–1.7 times of the former at the same location.