Development of multi-function torsional shear apparatus and evaluation of cyclic deformation-strength characteristics of sand under various stress conditions

多功能扭剪装置研制及不同应力条件下砂土循环变形-强度特性评价

• 批准号: 06555135
• 负责人: TOKI Shosuke
• 金额: $ 4.48万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06555135/
• 关键词: Torsional shear test; Liquefaction; Flow failure; Ocean wave loading; Earthquake; Sandy soil; Volcanic soil; Small strain; 変形特性; 試験装置; 破砕性; 模型実験; 三軸試験; 液状化解析; 火山灰質土; 繰返し変形特性

In this study, low cost, high resolution and high performance direct drive motor (DDM) used as axial and torsional loading equipment of torsional shear apparatus. In this DDM,changes of position, torque, speed control mode can be done easily by signals from a computer through the RS232C during testing.To examine the effects of loading controlled conditions on the cyclic deformation characteristics of sand under wide range of strain level, axial load (torque) and axial displacement (rotation angle) controlled cyclic triaxial (torsional) shear tests were performed by the above DDM loading system. And also, displacement and load controlled undrained cyclic triaxial and torsional tests to obtain the liquefaction strength were performed.Test result showed that :1) Axial load (torque) and axial displacement (rotation angle) controlled tests under wide range of strain levels can be performed by the developed loading equipment usign DDM.2) In the load controlled undrained cyclic test, the shear modulus and the damping ratio are not continuously measured at strain revel upper about 0.1%. The reason for this is that the strain kincreases rapidly due to the decrease of effective confining pressure. On the other hand, in the displacement controlled undrained cyclic test. cyclic deformation properties are continuously measured at large strain level.3) There existed a unique rule between results of load and displacement controlld liquefaction tests. This rule was independent of the relative density, the loading cycles and the types of tests (triaxial and torsional). On the basis of this relation, the cyclic strength in load controlled tests can be evaluated to some extent by performing displacement controlled cyclic tests.

本研究采用低成本、高分辨率、高性能的直驱电机（DDM）作为扭剪仪的轴向和扭转加载装置。为了研究加载控制条件对砂土循环变形特性的影响，在该加载系统上进行了轴向载荷（扭矩）和轴向位移（转角）控制的循环三轴（扭）剪试验。试验结果表明：1）所研制的DDM型加载设备可在较宽的应变水平范围内进行轴向载荷（扭矩）和轴向位移（转角）控制的不排水循环试验; 2）在载荷控制的不排水循环试验中，当应变水平高于0.1%时，剪切模量和阻尼比不需要连续测量。其原因是由于有效围压的降低，应变k迅速增大。另一方面，在位移控制的不排水循环试验中。在大应变水平上连续测定了循环变形特性。3）荷载控制液化试验与位移控制液化试验结果之间存在着独特的规律。这一规律与相对密度、加载周期和试验类型（三轴和扭转）无关。根据这一关系，可以通过位移控制循环试验在一定程度上评价荷载控制循环试验的强度。

项目成果

山下聡: "異なる直接型せん断試験装置による砂と粘土の変形強度特性" 直接型せん断試験の方法と適用に関するシンポジウム発表論文集. 1. 167-172 (1995)

Satoshi Yamashita：“使用不同直剪试验装置的砂和粘土的变形强度特性”直剪试验方法和应用研讨会论文集1. 167-172 (1995)。

三浦 清一: "火山性粗粒土の動的力学特性におよぼす応力履歴の影響" 火山灰質土の性質とその設計・施工シンポジウム論文集. 1. 229-236 (1995)

Seiichi Miura：“应力历史对火山粗粒土动态力学特性的影响”火山灰土特性及其设计和施工研讨会论文集 1. 229-236 (1995)。

Miura, S., and Kawamura, K.: "A procedure minimizing membrane penetration effects in undrained triaxial test" Soils and Foundations. Vol.36, No.4. 119-126 (1996)

Miura, S. 和 Kawamura, K.：“在不排水三轴试验中最大限度地减少膜渗透效应的程序”土壤和基础。

三浦清一: "消波構造物を支持する地盤の波浪による流動化機構の研究" 海岸工学論文集. 42・2. 1016-1020 (1995)

三浦精一：“地面支撑消波结构的波致流化机理研究”海岸工程杂志42・2（1995）。

Yamashita, S., Shibuya, S., Takahashi, T., Hirata, H., Takada, M.and Chiba, T.: "Deformation-strength character istics of sand and clay obtained from diferent direct shear test apparatuses" Proc.of the Symposium on Direct Shear Test Method and Its Applica

Yamashita, S.、Shibuya, S.、Takahashi, T.、Hirata, H.、Takada, M.和 Chiba, T.：“从不同直剪试验装置获得的砂和粘土的变形强度特征”Proc。