INFLUENCE OF STRESS RELEASE ON SAMPLE QUALITY OF PLEISTOCENE CLAY COLLECTED FROM LARGE DEPTH IN OSAKA BAY
INFLUENCE OF STRESS RELEASE ON SAMPLE QUALITY OF PLEISTOCENE CLAY COLLECTED FROM LARGE DEPTH IN OSAKA BAY
复制标题
应力释放对大阪湾大深度更新世粘土样品质量的影响
DOI：
10.3208/sandf.41.4_17
复制
发表时间：
2001
影响因子：
3.7
通讯作者：
T. Tsuchida
中科院分区：
文献类型：
--
作者：
Y. Watabe;T. Tsuchida
从大深度收集的大坂湾更新世粘土的无侧限抗压强度的数据集往往是非常分散的。这是因为在所收集的样品中的大的应力释放。更详细地，可能考虑以下两个因素。在完全饱和的土壤中，大于98.1 kPa的残余有效应力显然是不可能的，因为不存在大于真空的负压，并且当从取样器中挤出样品时和在修整过程中在样品中产生一些裂缝。通过对大坂湾40- 200 m深度的土样进行吸力和无侧限压缩试验，研究了残余有效应力与土样不排水抗剪强度之间的关系。吸力大于98.1千帕，测量从大深度的原状样品，通过施加回气压。Okumura（1974）定义的扰动比范围为1.5 ~ 3，这意味着样品显示出高达15%的小强度降低。结果表明，在考虑有效应力和不产生裂缝的情况下，从大深度采集的原状更新世粘土样品的质量是很好的。然而，大坂湾更新世粘土的无侧限抗压强度往往表现出很大的差异，由于裂缝类型的干扰，是在修剪标本。
A data set of unconfined compression strengths of Osaka Bay Pleistocene clays collected from large depths tends to be much scattered. This is because of large stress release in the collected sample. In more detail, the two following factors are possibly considered. A residual effective stress larger than 98.1 kPa is apparently impossible in a fully saturated soil because a negative pressure greater than a vacuum is non-existent, and some cracks are created in a sample when extruding it from the sampler and during trimming. In this study, a series of suction and unconfined compression tests for samples collected from 40-200m depths in Osaka Bay was carried out to investigate the relationship between the residual effective stress and the undrained shear strength. Suction larger than 98.1 kPa was measured in undisturbed samples collected from large depths by applying a back air pressure. The disturbance ratio defined by Okumura (1974) ranges from 1.5 to 3, implying that the samples show a small strength reduction of up to 15%. It is concluded that the quality of the undisturbed Pleistocene clay sample collected from a large depth is very good, if the effective stress is of concern and no crack is created. However, the unconfined compression strength of Osaka Bay Pleistocene clay tends to show a large variance due to the crack type disturbance that is created when trimming the specimen.