Investigation of the Landslip by the Bifurcation Theory and the Finite Element Method using Incompatible Elements

用分岔理论和不相容元有限元法研究山体滑坡

基本信息

批准号：
11450181
负责人：
YATOMI Chikayoshi
金额：
$ 2.3万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11450181/
关键词：
Bifurcation Theory Shear Band Finite Element Method Incompatible Element Cam-clay Model Finite Deformation Theory Implicit Method Cam-Clayモデル有限実形理論

项目摘要

1) Bifurcation Analysis in a Circular Cylinder of Coaxial and Non-coaxial Cam-clay Models. We obtain the exact solutions for all diffuse modes under symmetric and anti-symmetric deformation for coaxial and non-coaxial Cam-clay model., We find that, for a non-coaxial model, the bifurcation loads for all modes exist and nearly equal for a compressive test; however, the load for an extended test takes its minimum in a - constriction mode. These results agree well with the experimental deformation pattern of saturated clays. We then find that for a non-coaxial model, judging from the distributions of the maximum strain, the predicted net-like slip planes agree well with the observed slip pattern in the compressive test of clays. We find also, for a coaxial model, the bifurcation load for an ax symmetric bulging mode, which is often observed in the experiments, does not exist. This shows that the non-coaxial terms are indispensable to investigate the landslip.2) Finite Element Method Analysis of Soil/Water Couping Problems using an Implicit Calculation Algorithm. We develop a new method of implicit, finite element analysis of soil / water coupling problems in a well-known Cam-clay model. The implicit return mapping scheme is based on the elastic predictor and the plastic corrector. Some examples of the implicit method show the high accuracy and much reducing the total CPU time.3) Finite Element Analysis with the Incompatible Elements and the Examination of the Accuracy. As a basic research on the landslip, we developed a strong discontinuity finite element analysis with the displacement discontinuity inside the elements, which solutions are mesh-independent. We then estimate the method by means of verifying the accuracy of the fracture energy by using the E-integral. As a result, we find that the strong discontinuity analysis is high accurate in view of the fracture energy.

1) 同轴和非同轴 Cam-clay 模型圆柱体的分岔分析。对于同轴和非同轴 Cam-clay 模型，我们获得了对称和反对称变形下所有扩散模态的精确解。我们发现，对于非同轴模型，所有模态的分叉载荷均存在且几乎相等压缩测试；然而，扩展测试的负载在收缩模式下达到最小值。这些结果与饱和粘土的实验变形模式非常吻合。然后我们发现，对于非同轴模型，从最大应变的分布来看，预测的网状滑移面与粘土压缩试验中观察到的滑移模式非常吻合。我们还发现，对于同轴模型，实验中经常观察到的轴对称凸出模式的分叉载荷并不存在。这说明非同轴项对于研究滑坡是不可缺少的。2)基于隐式计算算法的土/水耦合问题的有限元分析。我们开发了一种新方法，可以在著名的 Cam-clay 模型中对土/水耦合问题进行隐式有限元分析。隐式返回映射方案基于弹性预测器和塑性校正器。隐式方法的一些例子表明其精度高，并且大大减少了总的CPU时间。3)不相容单元有限元分析及精度检验。作为滑坡的基础研究，我们开发了一种强不连续性有限元分析，其单元内部具有位移不连续性，其解与网格无关。然后我们通过使用 E 积分验证断裂能的准确性来估计该方法。结果，我们发现考虑到断裂能，强不连续性分析具有很高的准确性。