Mechanical characteristics of weathered rocks and soils for hazard assessment of slope areas.

主要结论如下：(1)新泻县东库比基地区分布着多个第三纪类型滑坡。该区滑坡的发生频率与基岩地质条件有关。从分布于Teradomari、Shiiya和Nishiyama地质建造的滑坡地区采集了几个未风化和风化的泥岩样品。对这些试件进行了单剪和环剪试验。风化泥岩样品比未风化泥岩样品具有更高的抗剪强度。这种现象可能与化学风化过程中矿物蚀变引起的滑坡滑动面抗剪强度变化有关。(2)对第三系滑坡和晶片岩滑坡滑动面粘土试件进行了三轴压缩试验和环剪试验。这些试件的残余抗剪强度的内摩擦角在5到30度之间。他们的样本角度为…更多的第三系滑坡比结晶片岩滑坡的样品少约10度。这一事实与两种滑坡的坡度差异相吻合。化学风化降低了粘土样品的镁含量，残留物中铁、铝组分相对增加。绿泥石、蒙皂石等膨胀矿物与滑动面粘土的抗剪强度降低密切相关。(3)滑坡运动受基岩地质和土性控制，形成独特的地形地貌。这一次，山体滑坡的形状很相似。相比之下，爬行滑坡的形态特征是各种局部崩塌的集合体。分布在第三系沉积物中的滑坡坡度小于30度。特别是在泥岩地区，坡度在18度左右。分布在火山岩中的滑坡具有30度以上的坡度，其运动类似于岩石滑坡或岩崩。(4)分布在结晶片岩中的滑坡坡度为15~35度，分布在第三系沉积物中的滑坡坡度为10~20度。第三系沉积物中滑坡的长度、宽度和面积均大于晶片岩中的滑坡。然而，第三系沉积物中滑坡的滑动面深度比结晶片岩中的要浅，第三系沉积物中滑坡的地下水位一般都很浅，而且接近地表。另一方面，许多晶片岩滑坡的地下水位比它们的滑动面更深。较少

Followings are conclusive summary of our investigation.(1)Many tertiary type landslides are distributed in the Higashikubiki area, Niigata Prefecture. Frequency of landslide occurrences in this area is related to the bedrock geology. Several non-weathered and weathered mudstone samples were collected from landslide areas distributed in Teradomari, Shiiya and Nishiyama geologic formations. Simple and ring shear tests were carried out on these samples. Weathered mudstone samples exhibited higher shear strength than non-weathered mudstone samples. Such phenomenon might depend on the changes of shear resistance of the slip surface of landslides caused by alteration of minerals during chemical weathering.(2)Triaxial compression test and ring shear test were carried out on clay samples of sliding surfaces in Tertiary type landslides and crystalline schist landslides. Angles of internal friction of residual shear strengths of these samples range from 5 to 30 degree. Their angles of samples fr … More om Tertiary landslides are less approximately 10degree than those of samples from crystalline schist landslides. This fact is concordant with difference of slopes between the two type landslides. Mg content of clay samples is reduced through chemical weathering, ferric and aluminum components are residua relatively increase. Swelling minerals such as chlorite and smectite are closely connected to the lowering shear resistance of clay of sliding surface.(3)Landslide movements are controlled by bedrock geology and characteristics of soils, and produce unique topographic features. Landslides for once are similar in shape. Creeping landslides, in contrast, are morphologically characterized by aggregates of various partial slumps. Slopes of landslides distributed in Tertiary sediments show less than 30 degree. Slopes of them, in particular, show around 18 degree in mudstone area. Landslides distributed in volcanics show more than 30 degree of slope and their movements are similar to rock slide or rock avalanche.(4)Slopes of landslides distributed in crystalline schist and in Tertiary sediment range from 15 to 35 degree and from 10 to 20 degree, respectively. Sizes of landslides such as length, width and area in Tertiary sediments are larger than those in crystalline schist. The depth of sliding surfaces of landslides in Tertiary sediments, however, is shallower than those in crystalline schist.Groundwater tables in landslides in Tertiary sediments are generally shallow and close to surface. On the other hand, many landslides in crystalline schist have deeper groundwater tables than their sliding surfaces. Less