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Study on undrained and residual strength of clay soils having no true cohesion

无真粘性黏土的不排水及剩余强度研究

基本信息

批准号：
08455222
负责人：
YAGI Norio
金额：
$ 3.01万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455222/
关键词：
clay soil undrained strength residual strength angle of shearing resistance triaxial compression test ring shear test clay mineral 有効応力間隙水圧係数

项目摘要

There exist many clay soils which have no true cohesion in Japan.Shear strength of such a clay soil can be determined by the angle of shear resistance phi' and pore water pressure generated during shear, that is, the coefficient of pore water pressure A_f at failure. We carried out the triaxial compression and the ring shear tests for many clay soils sampled from landslide sites and the seabeds. Also we conducted mineral analyzes to investigate influence of clay minerals on the strength parameter. Conclusions are as follows.1.The clay soil which has no true cohesion has an unique angle of shearing resistance phi' regardless of states of clay soil.2.A clay which has lower water soil than so called normally consolidated clay soil can obtained by remolding and reconsolidating soil. Such a clay soil is also normally consolidated state. A_f of this clay soil increases with consolidation pressure, though it is constant for the so called normally consolidation state. The angle of shear resistance phi' from the plain strain test is not always bigger than one from the triaxil test.3.The angles shear resistance phi' and phir corresponding to the residual strength become small if the clay soil contains clay minerals such as expansive chlorite, talc and montmorillonite. It is problem that difference between phi' and phi_r becomes big. This difference is also big when minerals mentioned above is containe.

日本存在许多不具有真正粘聚力的粘土。这种粘土的抗剪强度可以通过抗剪力phi'与剪切时产生的孔隙水压力的角度来确定，即破坏时的孔隙水压力系数A_f。我们对从滑坡现场和海底采集的许多粘土进行了三轴压缩和环剪试验。我们还进行了矿物分析，以研究粘土矿物对强度参数的影响。结论如下：1.不具有真正粘聚力的粘土，无论其状态如何，都具有独特的抗剪角phi'。2.通过对土进行重塑和再固结，可以获得比通常固结粘土更低的水土含量的粘土。这种粘土通常也是固结状态。这种粘土的 A_f 随着固结压力的增加而增加，尽管对于所谓的正常固结状态来说它是恒定的。平应变试验的抗剪角phi'并不总是大于三轴试验的抗剪角phi'。3.如果粘土中含有膨胀性绿泥石、滑石粉、蒙脱石等粘土矿物，则与残余强度相对应的抗剪角phi'和phir会变小。 phi'和phi_r之间的差异变大是问题。当含有上述矿物质时，这种差异也很大。