Predict Failure of Shirasu Slope in Consideration of Patterns of Rainfall and Unsaturated Seepage

Shiras是一种广泛分布于日本九州南部和油区的浮水流沉积土，因其频繁受到降雨和地震的破坏而被认为是典型的湿陷性土。这种土壤似乎与新西兰北岛的黄褐色浮石土、美国的胶结砂和中美洲的火山灰土相似。未受干扰的白松的强度特性与受干扰的白松不同，因为未受干扰的样品由于地质原因而具有抗拉强度。众所周知，白松在增加水分含量后会变得非常容易折叠。许多实验室对降雨对边坡的破坏进行了大量的研究。由于降雨对白露的破坏机制非常复杂，白露的破坏机制尚未明确。所得结论如下：(1)九州南部降水格局逐渐明朗。(2)明确了白松非饱和渗透系数、体积含水量与吸力之间的关系。(3)三轴试验结果明确了白松地区土壤力学和液化特征。(4)本文研究了降雨条件下白露边坡非饱和渗流特征。

Shiras is a pumic-flow deposit soil widely distributed in southern Kyushu and oilier districts in Japan, and is counted to be a typical collapsible soil for its frequent damages mainly owning to rainfall and earthquakes. Such a soil seems to be similar to the yellow-brown pumice soil in North Island, New Zealand, the cemented-sand in the U. S. A., and the volcanic ash soil in Central America. The strength characteristics of the undisturbed Shirasu are different from those of the disturbed Shirasu, since undisturbed samples have tensile strengh due to a geological cause.It is well known that Shirasu becomes very collapsible after increasing the moisture content. Many studies on failure of slope by rainfall have been done by many laboratories. The failure mechanism of Shirasu has not been clarified yet, because the mechanisum of it by rainfall is very complicated.The conclusion drawn were as follows ;(1) The patern of rainfall in Southern Kyushu was become clear.(2) This study make it clear about the relation between unsaturated coefficent of permeability, water content by volume and suction of Shirasu.(3) The triaxial test results make clear characteristics of soil mechanics and liquefaction in Shirasu.(4) This paper refers to characteristics of unsaturated seepage of Shirasu slopes in raifall.