Residual Strength of Soils and Its Application in Landslide Stability Analysis

剪切变形中的土壤残余状态是剪切过程中土壤体积变化为零时的状态，并且当剪切面上的所有土壤颗粒重新定向到剪切方向时获得。土体的残余状态在滑坡稳定性问题中起着重要的作用，因为滑带土的强度取决于滑带土在长期滑动后的残余状态。因此，研究滑坡土体在残余状态下的强度特性并将其应用于稳定性分析是非常重要的。本研究包括两个主要的实验室研究：1）滑坡土的强度特性和2）粘土矿物对土壤强度的影响。然后，将调查结果用于滑坡的稳定性分析。从四国不同的滑坡现场获得了几个土壤样品，代表了实验室测试的各种地质条件。用ri法研究了其强度性能 ...更多信息 NG剪切装置的基础上直接以及简单的剪切原理，并通过X射线衍射分析的矿物性质进行了研究。研究结果如下：第一，直剪式环剪仪测定的强度与单剪式环剪仪测定的强度有许多不同之处。这是因为直接剪切型设备具有预先指定的剪切平面，这可能导致具有较高含量的较细颗粒的土壤的较低残余强度和具有较高百分比的较粗颗粒的土壤的较高强度。相比之下，简单的剪切型仪器给出了相对准确的结果，因为土样通过试样整个深度中的最弱平面被剪切。其次，四国滑坡土壤的抗剪强度被调查为非常低，这主要是由于滑面土壤中存在大量的膨胀粘土矿物。X射线衍射试验表明，滑坡土中的膨胀土含量较高，特别是变质岩类滑坡土中的膨胀土含量较高，对滑坡土强度的降低起着重要作用。第三，稳定性分析结果表明，滑带土，特别是在大型滑坡的情况下，已达到残余状态，这是证实了一些活动的滑坡反分析。最后认为，将室内测定的强度参数应用于滑坡稳定性分析，在许多方面比进行反分析更具可行性。少

Residual state of a soil in shear deformation is a state when change in soil volume during the shear is zero, and it is attained when all the soil particles on the shear planes get reoriented toward the shear direction. Residual state of soil plays a significant role in landslide stability problems because strength of slip surface soil is governed by the residual conditions after having slid for a long duration. It is therefore important to investigate the strength behaviors of landslide soils at their residual states and to employ them in the stability analysis. This research includes two major lab investigations: 1) strength properties of landslide soils and 2) influence of clay minerals on soil strength. The investigation results were then employed in carrying out stability analysis of the landslides. Several soil samples were obtained from various landslide sites in Shikoku representing various geological conditions for the lab tests. The strength properties were investigated by ri … More ng shear apparatuses based on direct as well as simple shear principles, and the mineral properties were investigated by x-ray diffraction analysis. The investigation results are summarized as follows.First, the strength measured by direct shear type ring shear apparatus was found to differ in many aspects from that by the simple shear type. It is because the direct shear type apparatus possesses a pre-specified plane of shear, which may result in a lower residual strength of a soil with higher content of finer particles and a higher strength of a soil with higher percentage of coarser particles. In contrast, a simple shear type apparatus gives comparatively accurate results because the soil sample gets sheared though the weakest plane in the entire depth of specimen. Second, the shear strength of landslide soils in Shikoku was investigated to be very low, which is mainly due to a significant amount of expansive clay minerals in the slip surface soil. The x-ray diffraction tests revealed that the amount of expansive chlorite in landslide soils originated from metamorphic rocks in particular is high, which plays a significant role in lowering the soil strength. Third, the stability analyses results showed that the slip surface soils, especially in case of large-scale landslides have reached the residual state, which was confirmed by back analysis of some active landslides. Finally, it was considered that application of lab-determined strength parameters in stability analysis for the landslides is more feasible in many aspects than carrying out back analysis. Less