A STUDY ON MOVEMENT OF SOIL PARTICLES AND DEFORMATION OF SOIL UNDER POST LIQUEFACTION STATE

液化后状态下土壤颗粒运动与变形的研究

• 批准号: 15560426
• 负责人: SASAKI Yasushi
• 金额: $ 2.18万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560426/
• 关键词: LIQUEFATION; GROUND DEFORMATION; MIXTURE; CCD KAMERA; RCONSTRUCTION OF SKELETON; DILATANCY; SETTLEMENT OF EMBANKMENT; DEFORMATION CLCULATION; 地盤流動

In order to mitigate seismic damage due to soil liquefaction by proper measure, precise evaluation of possible deformation of ground is essential. So, it has been desired to establish a better method for predicting soil deformation due to soil liquefaction. Deformation characteristics of soil during post liquefaction state were investigated experimentally in this research. Post liquefaction state was made by two ways : one is instantaneous liquefaction by shock, and the other is by cyclic shaking. Deformation of soil skeleton was monitored by observing the movements of soil particles and the effects of these movements to soil deformation were examined. The torsional shear tests were also conducted to clarify the characteristics of strength of liquefied soil. The obtained results are as follows.1)In the case of horizontal ground, soil skeleton is completely destroyed by instantaneous liquefaction. So, the soil particle becomes suspended state after liquefaction. The continuing time of t … More his suspended state is governed by the necessary time for the soil particles move down until the soil skeleton is rebuild.2)When the lateral boundary of a ground is movable, mixture of water and suspended soil particles can move laterally in accord with boundary movement. In such a case, movement of soil particles is delayed than the movement of water, because the mass of a soil particle is larger than the one of water. This delay causes reconstruction of skeleton structure, so the reduction of excess pore water pressure due to the dilatancy is easily triggered.3)In case of the liquefaction by a cyclic shaking, the excess pore water pressure cyclically rises up and drops down, because of both reversing of shear stress direction and ground deformation.4)Settlement of an embankment due to the liquefaction of foundation ground progresses while the pore pressure is kept to be high. It was shown that the settlement process of such embankment can be analyzed by treating the liquefied layer as viscous liquid. In case the liquefied state is cyclically brought about, the settlement is brought about during the short periods while the pore water pressure is raised high. And the total settlement amount is an accumulation of each settlement.5)The calculated result of embankment by using this algorithm agrees well with results of shaking table tests even for the time history of settlement.Summarizing the above results, it is found that the liquefied ground behaves like liquid even though it keeps for limited time. It is also clarified that the duration of liquid-like state continued until the skeleton structure is reconstructed. And the reconstruction of skeleton structure is made by the sedimentation of soil particles or the movement of mixture of water and soil particles. This means that it is needed to introduce dynamics of the solid-liquid mixture in the analysis of soil deformation in post liquefaction state. Less

为了采取适当的措施减轻由于土壤液化引起的地震破坏，精确地评估地基可能的变形是必要的。因此，建立一种较好的液化变形预测方法一直是人们所期望的。本文对液化后土体的变形特性进行了试验研究。液化后状态的形成有两种方法：一种是冲击瞬时液化，另一种是循环振动液化。通过观测土颗粒的运动来监测土骨架的变形，并分析了土颗粒的运动对土变形的影响。通过扭剪试验研究了液化土的强度特性。结果表明：1）在水平场地情况下，土体骨架在瞬间液化作用下完全破坏。因此，液化后的土颗粒成为悬浮状态。t的持续时间 ...更多信息 悬浮状态取决于土颗粒向下运动直至土骨架重建所需的时间。2）当地面侧边界可动时，水和悬浮土颗粒的混合物可随边界运动而雅阁。在这种情况下，土壤颗粒的运动比水的运动延迟，因为土壤颗粒的质量大于水的质量。这种滞后引起骨架结构的重构，从而容易触发超静孔隙水压力因振动而降低。3）在周期性振动液化的情况下，超静孔隙水压力周期性地上升和下降，由于剪应力方向的反转和地面变形地基液化引起的路堤沉降在保持较高孔隙水压力的同时不断发展。结果表明，将液化层视为粘性液体，可以分析此类路堤的沉降过程。如果液化状态是循环产生的，则在孔隙水压力升高的短时间内产生沉降。用该算法计算的路堤沉降量与振动台试验结果吻合较好，说明液化地基即使在有限时间内也表现出流体的特性。这也表明，类液体状态的持续时间，直到骨架结构的重建。骨架结构的重建是通过土颗粒的沉降或水和土颗粒混合物的运动实现的。这意味着在液化后土壤变形分析中需要引入固液混合动力学。少

项目成果

Influence of shear deformation on the duration of liquefaction

剪切变形对液化持续时间的影响

• 发表时间: 2004
• 期刊: Proceedings of the annual conference of Chugoku branch Japanese Society of Civil Engineering
• 作者: 上俊 二;藤原 東雄;桑嶋 啓治;竹林 泰佑;岡吉 則;Takashi Ikeoka;木寺 寛;池岡 孝;西田 将人;村川 奉嗣;Masato Nishida
• 通讯作者: Masato Nishida

せん断変形が液状化継続時間に与える影響

剪切变形对液化持续时间的影响

• 发表时间: 2004
• 期刊: 平成16年度土木学会中国支部研究発表会講演概要集
• 作者: 上俊 二;藤原 東雄;桑嶋 啓治;竹林 泰佑;岡吉 則;Takashi Ikeoka;木寺 寛;池岡 孝;西田 将人
• 通讯作者: 西田 将人

液状化地盤の剛性回復ひずみ量

液化地面刚度恢复应变

• 发表时间: 2005
• 期刊: 第40回地盤工学研究発表会平成17年度発表講演集 (発表予定)(印刷中)
• 作者: 上俊二;藤原東雄;桑島啓治;福田靖;尼崎貴大;岡吉則;木寺 寛
• 通讯作者: 木寺 寛

Amount of the strain of liquefied ground where the rigidity is recovery

刚度恢复时液化地面的应变量

• 发表时间: 2005
• 期刊: Proceedings of the 40^<th> annual conference of the Japanese Geotechnical Society (in press)
• 作者: 上俊 二;藤原 東雄;桑嶋 啓治;好村 純一;Hiroshi Kidera
• 通讯作者: Hiroshi Kidera

Experimental study on the estimation of the settlement of the embankment based on the deformation characteristics of liquefied ground below it and rearrangement of its compression

基于路堤下方液化地层变形特征及其压缩重排的路堤沉降估算试验研究

• 发表时间: 2004
• 期刊: Proceedings of the 39^<th> annual conference of the Japanese Geotechnical Society
• 作者: 上俊 二;藤原 東雄;桑嶋 啓治;竹林 泰佑;岡吉 則;Takashi Ikeoka;木寺 寛;池岡 孝;西田 将人;村川 奉嗣;Masato Nishida;Tomotsugu Murakawa
• 通讯作者: Tomotsugu Murakawa