Study on the assessment of shear strength characteristics of non-sedimentary natural soils with the consideration of inhomogeneity and void ratio

本研究的目的是建立一种方法来评估这些土壤的抗剪强度特性，目前的土力学理论不会毫无困难地应用。这些土的特点是它们的应力历史是未知的，在特定条件下很难制备试样。作为这类土的代表，研究了两种火山土，戴森松江浮石（）和戴森仓吉浮石（DKP），从山。戴森在Tottor县。对其原状试样进行了三轴和直剪箱试验。通过室内直剪箱试验，在剪切前固结阶段测定吸力，研究吸力对土体抗剪强度的影响，主要结论如下：（1）当剪切过程中正应力大于固结屈服应力时，土体抗剪强度与正应力、孔隙比的关系与沉积粘性土相似; ...更多信息 以此为参考，对正应力低于固结屈服应力时的剪切特性进行了评价。结果表明，当正应力小于固结屈服应力时，即使孔隙比大于参考值，抗剪强度仍有可能大于参考值。（2）对于含水量不均匀的土样，可能不会产生单调的粒径分布曲线。通过采用在水中进行筛分并通过直接测量来确定样品的总干质量的方法来解决这个问题。（3）吸力随正应力的增大而减小，当正应力大于固结屈服应力时吸力为零。在相同的正应力值下，剪切强度与剪切前试样所具有的吸力唯一相关。这表明吸力是控制剪切强度的重要因素。当正应力低于固结屈服应力时，考虑吸力是至关重要的。少

The objective of this study is to establish a way of assessing shear strength characteristics of those soils to which current theories of soil mechanics would not be applied without difficulty. Those soils are characterized by that their stress histories are not known and that specimens will be difficult to prepare under specified conditions.As representatives, of such soils, two volcanic soils, Daisen Matsue pumice (DMP) and Daisen Kurayoshi pumice (DKP), from Mt.Daisen in Tottor Prefecture, were studied. Triaxial and direct shear box tests were conducted on their undisturbed samples. In some direct shear box tests, the suction was measured, in the stage of consolidation prior to shearing, to examine the effects of suction on the shear strength.Main conclusions are as follows :(1)The interrelationship between shear strength, normal stress and void ratio are similar to those of sedimentary cohesive soils when the normal stress during shear is higher than the consolidation yield stress. … More Using the interrelationship as a reference, the characteristics in shear tinder the normal stress lower than the consolidation yield stress were assessed. Results showed that, under the normal stress lower than the consolidation yield stress, the shear strength would possibly be higher than the reference value even with the void ratio higher than the reference value.(2)Monotonous curves of particle size distribution might not be resulted in for soils without uniform water content, like samples used in this study. This problem was fixed by employing the method in which sieving was done in water and the total dry mass of sample was determined by direct measurement.(3)The suction will decrease as the applied normal stress increases and will be null under the normal stress over the consolidation yield stress. Under an identical value of the normal stress, the shear strength can uniquely be related to the suction that specimens possess before the shearing. This indicates that the suction is an important factor controlling the shear strength. It will be crucial to consider the suction especially when the normal stress is lower than the consolidation yield stress. Less