Research on the collapse prediction of unsaturated Shirasu slopes in earthquake

Shirasu有很大的浮石。原状砂砾土看起来像软岩这样的脆性物质，但砂砾土被称为颗粒土。在含有可破碎颗粒的火山土Shirasu上进行了一系列不排水的单调三轴试验。结果表明，石拉苏的不排水循环和单调剪切特性与围压及其密度有很大关系。试验结果表明：(1)石拉苏的单调和循环不排水剪切特性与围压有很强的相关性，而托尤阿砂与围压无关。(2)松散石拉苏的偏应力比和轴向应变随初始有效围压的增大而增大。密实石拉苏的偏应力比随初始围压的增大呈相反的减小趋势。(3)松散石拉苏的剪切特性随初始有效围压的增大而增大。另一方面，对于致密的Shirasu，随着初始围压的增加，表现出越来越大的收缩行为，就像通常在砂质中发现的那样。

Shirasu has large pumice stone. Undisturbed Shirasu is seemed such brittle material as soft rock, but disturbed Shirasu is known as a granula soils. Aseries of undrained monotonic triaxial tests has been performed on a volcanic soil Shirasu which has crushable particles. As a result, the undrained cyclic and monotonic shear behavior of Shirasu is found to greatly dependent on the confining pressure and its density. Testing was performed on disturbed spcimens.(1) The monotonic and cyclic undrained shear behavior of Shirasu shows a strong dependence on confining pressure, Toyoura sand does not.(2) In the deviator stress ratio and axial strain for loose Shirasu the deviator stress ratio increased with increasing initial effective confining pressur. The deviator stress ratio for dense Shirasu had the opposite trend of decreasing with increasing initial confining pressure.(3) The shear behavior of loose Shirasu showed increasing dilative characteristics with increasing initial effective confining pressur. That for dense Shirasu, on the other hand, showed increasingly contractile behavior with increasing initial confining pressur as is generally found for sandy.