Slope failure mechanism for crushable volcanic soi I at snowy cold region and its modeling

通过对可破碎土边坡稳定性的试验和数值研究，得出以下结论：1.冻融顺序对火山土静态力学行为的影响(1)火山粗粒土由于冻融顺序的重复而发生明显的颗粒破碎。颗粒破碎对火山土的静强度和刚性影响很大。(2)在低围压条件下，经历冻融过程的火山土具有明显的可碎性。冻融顺序对火山土动态力学行为的影响(1)火山粗粒土的剪切模量值因冻融顺序的影响而降低。另一方面，冻融作用对滞回阻尼率的影响较小。(2)火山土的液化抗力因冻融顺序的影响而减小。这一事实可能会…(1)从模型试验结果可以看出，超孔隙水压力和饱和度对边坡的破坏起着关键作用。(2)边坡中防渗层的深度和形状是评价边坡稳定性的关键。4.易破碎火山土降雨诱发边坡破坏的数值分析(1)DEM数值分析表明，提出了土体颗粒间的小孔隙单元，并对其进行了数值模拟。非连续变形分析(DDA)如果在分析算法中适当地估计了降雨和剪胀对火山土的影响，就可以解释边坡的破坏机理。较少

Based on the experimental and numerical studies of slope stability of crushable soils, the following conclusions are obtained:1.Effect of freeze-thaw sequence on static mechanical behavior of volcanic soil(1)Particle breakage of volcanic coarse-grained soil significantly occurs due to the repetition of freeze-thaw sequence. The particle breakage affects strongly on static strength and rigidity of volcanic soil.(2)Volcanic soil subjected to freeze-thaw sequences may produce a remarkable crushability at low confining pressure level. This fact suggests that deterioration in the stability of slope near the surface is significant on snowy cold region.2.Effect of freeze-thaw sequence on dynamic mechanical behavior of volcanic soil(1)Shear modulus of volcanic coarse-grained soil decreases due to freeze-thaw sequences. On the other hand, freeze-thaw action may less affect hysteresis damping ratio.(2)Liquefaction resistance of volcanic soil decreased due to freeze-thaw sequences. This fact may … More attribute the reduction of the liquefaction resistance to the increase in finer content induced by particle breakage during freeze-thaw sequences.3.Rainfall-induced slope collapse for crushable volcanic soil and its evaluation(1)From the results of model tests, it is found that excess pore water pressure and saturation degree play a key role in the slope failure induced by rainfall.(2)Depth and shape of impermeable layer in the slope are critical to estimate the stability of slope.4.Numerical analysis for rainfall-induced slope failure for crushable volcanic soil(1)A series of numerical analysis by DEM showed that proposed small void elements between soil particles, which are able to expand in accordance with temperature depression, can simulate the mechanical freeze-thaw performance of granular materials.(2)Discontinuous Deformation Analysis (DDA) could explain the slope failure mechanism if rainfall and dilatancy effects on volcanic soil are estimated appropriately into analysis algorithm. Less