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.

本研究报告讨论了吸力对非饱和土抗剪强度的影响。实验采用冈山产的非饱和MASA土进行试验。测试样本在 MIKASA 教授开发的直剪装置的剪切箱中进行静态压实。通过装置下压板内嵌的陶瓷盘对试件施加吸力，在恒吸力条件下进行应力控制排水剪切试验。法向应力设置为1.0、2.0、3.0kgf/cm^2，吸力设置为0、0.1、0.2、0.4、0.6、0.8 kgf/cm^2。测试结果表明，剪切强度随着吸力的增加而增加。然而，在 0.4 kgf/cm^2 吸力范围内，剪切强度的增加可以忽略不计。正常压缩和过压缩的MASA土体表现出相同的抗剪强度随吸力增加的趋势。两球体之间孔隙水产生的粘结力导致有效法向应力增加，从而导致抗剪强度增加。力是在相同尺寸球体随机堆积的情况下进行理论计算的。吸力与剪切强度之间的理论关系与实验结果吻合良好。