Experimental Study on Mechanical Properties of Volcanic Ash Soils as Fill Materials for Barthfill Dams and Road Construction

为了研究关东壤土等火山灰粘性土作为土石坝和路基土的土料时的力学性质，如碾压循环荷载作用下强度降低(软化)、压实后触变强度恢复、压实荷载在填土中的传递等，对模型土进行了多次碾压试验，测量了压实过程中的土压力和孔压，并通过贯入试验和无侧限压缩试验研究了填土强度的时空变化。填土的强度随着压实的进行有一定程度的增加，但随着击实的进行，强度逐渐降低，随着击实的进行，强度逐渐降低。约为曲值最大值的45%。根据循环三轴试验的结果，Q值和静、动态变形模数是解释击实软化的良好指标，但由于强度数据的大分散性，在模型击实试验中很难识别强度恢复特性。另一方面，实验室试验表明，易软化材料的强度回复率较高，而Qc和Qu值由于对强度增长的不同反应，有时表现出不同的强度回复率。

In order to study mechanical properties of volcanic ash cohesive soil like Kanto-Loam, when utilized as earth materials for earthfill dams and subgrade soil under the pavement, such as strength reduction (softening) due to cyclic loading of roller compaction, thixotropic strength regain after compaction, and transmission of compacting load in the fill, several roller compaction tests were performed for model earthfills by measuring earth and pore-water pressures during compaction and spacial and time-dependent changes of strength of fill materials by cone penetration and unconfined compression tests.Strength of fill materials increases at first as compaction proceeds up to a certain extent but decreases gradually after than due to the collaps of soil skelton, by approximately 45 percent of the maximum value in qu-value. According to the results of cyclic triaxial tests, qu-value and static and dynamic deformation moduli are good indices to explain softening due to compaction.Strength regain properties were hard to recognize in model compaction tests because of large scatters of strength data. Laboratory tests on the other hand gave some suggestions that the rate of strength regain is higher for materials easy to soften, and than qc-and qu-values sometimes show different results for strength regain because of their different reactions in strength increase.