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

以下是我们调查的结论性总结。(1)新泻县东kubiki地区分布着大量第三系滑坡。该地区滑坡发生的频率与基岩地质有关。在分布于Teradomari、Shiiya和Nishiyama地质组的滑坡区采集了非风化泥岩和风化泥岩样品。对这些试样进行了简单剪切和环剪试验。风化泥岩样品的抗剪强度高于未风化泥岩样品。这种现象可能与化学风化过程中矿物的变化引起滑坡滑面剪切阻力的变化有关。(2)对三级滑坡和结晶片岩滑坡滑面粘土试样进行了三轴压缩试验和环剪试验。这些试样的残余抗剪强度内摩擦角范围为5 ~ 30度。第三系滑坡样品的夹角比结晶片岩滑坡样品的夹角小10度左右。这与两类滑坡的坡度差异是一致的。化学风化作用降低了粘土样品中Mg的含量，铁和铝组分的残留相对增加。绿泥石、蒙脱石等溶胀矿物与滑面粘土抗剪性能的降低密切相关。(3)滑坡运动受基岩地质和土壤特性控制，形成独特的地形特征。这一次的山体滑坡形状相似。相比之下，蠕变滑坡的形态特征是各种局部滑坡的聚集。分布在第三系沉积物中的滑坡坡度小于30度。尤其是泥岩区，其坡度在18度左右。分布在火山岩中的滑坡坡度大于30度，其运动方式类似于岩滑或岩崩。(4)在结晶片岩和第三系沉积物中，滑坡坡度分别为15 ~ 35°和10 ~ 20°。第三系沉积物中滑坡的长度、宽度和面积均大于结晶片岩中的滑坡。第三系沉积物中滑坡滑动面深度较结晶片岩浅。第三纪沉积物中滑坡的地下水位一般较浅且接近地表。另一方面，许多结晶片岩滑坡的地下水位比其滑动面深。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