Effect of suction on shear strength of soils

吸力对土体抗剪强度的影响

• 批准号: 03660245
• 负责人: SHIMADA Kiyoshi
• 金额: $ 1.22万
• 依托单位: Okayama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03660245/
• 关键词: Unsaturated soil; Masa soil; Suction; Direct shear test; Shear strength

This research report discusses the effect of suction on the shear strength of unsaturated soils.Unsaturated MASA soil produced in Okayama was used in experiments. The test specimens were statically compacted in the shear box of direct shear apparatus developed by Prof. MIKASA. Suction was applied to the specimens through the ceramic disc imbeded in the lower pressure plate of the apparatus.Stress-controlled drainage shear test were carried out under the condition of constant suction. Normal stress was set to 1.0, 2.0, 3.0kgf/cm^2 and suction to 0, 0.1, 0.2, 0.4, 0.6, 0.8 kgf/cm^2.The test result shows the increase of shear strength with the increase of suction. However, the increase of the shear strength is found to be negligible over the range of 0.4 kgf/cm^2 of suction. The normally compressed and over-compressed MASA soils show the same tendency of the increase of the shear strength with suction.The bonding force produced by the pore water between two spheres causes the increase of the effective normal stress, then the increase of the shear strength. The force is calculated theoretically under the condition of random packing of the same size spheres. The theoretical relationship between suction and shear strength shows the good agreement with the experimental results.

这份研究报告讨论了吸力对不饱和土壤的剪切强度的影响。在实验中使用了冈马产生的不饱和MASA土壤。测试样品在Mikasa教授开发的直接剪切设备的剪切盒中静态压实。通过在设备的较低压力板中嵌入的陶瓷盘将吸力应用于样品。在恒定吸力的条件下，进行了压力控制的排水剪切试验。正常应力设置为1.0、2.0、3.0kgf/cm^2，并吸入为0、0.1、0.2、0.4、0.6、0.8 kgf/cm^2。测试结果显示出随着吸力的增加而增加了剪切强度。然而，发现剪切强度的增加在抽吸的0.4 kgf/cm^2范围内可以忽略不计。正常压缩和过度压缩的MASA土壤表现出相同的剪切强度使用吸力增加的趋势。两个球之间的孔隙水产生的粘结力会导致有效的正常应力增加，然后剪切强度的提高。理论上在相同大小球体的随机堆积条件下计算该力。抽吸和剪切强度之间的理论关系表明与实验结果有着良好的一致性。