Basic research on the shear band formation by pulling out of anchor

本研究主要有以下三个目的：1。锚杆抽离剪切带形成机理的探索三维大变形弹塑性有限元分析程序的开发。寻找地基形状与破坏机制的相互作用。对0度、25度、35度地基边坡进行了锚杆在风荷载作用下的拉拔分析，得到了锚杆在风荷载作用下的荷载与挠度曲线及地表剪切带形态。采用柱式连接后，倾斜地面的拉拔阻力增大。利用关联流动规则和非关联流动规则，开发了三维大变形弹塑性有限元分析程序。后一条规律与实验结果的相关性要好得多。对平地和倾斜地基进行了三维分析，并与相关试验进行了对比。结果表明，计算得到的锚杆定位区与试验观测结果基本一致，锚杆抗拔强度随边坡角度的变化而变化。此外，还观察到了锚的旋转。最后进行了现场拉拔试验模拟，模拟了地表的力-位移曲线和滑动线。通过以下方式得出更现实的抽离行为将是未来的一个课题：1。的改进。分析程序执行中出现的渐进式失效。2.土壤异质性的评价。

This research has been conducted for the following three purposes :1.The search for the mechanism of shear band formation by the pulling out of the anchor.2.The development of three-dimensional large deformation elasto-plastic FEM analysis program.3.The search for the interaction of the shape of foundation and the failure mechanism.The pulling out analysis of the anchor by the wind load has been conducted for the ground slopes of 0, 25, and 35 degrees to obtain the curves of load and deflection and the form of shear bands on the surface. The tilted ground exhibited higher pulling out resistance by virtue of the use of the post connection.A three-dimensional large deformation elasto-plastic FEM analysis program has been developed with the use of associated and non-associated flow rules. The latter rule displayed much better correlation with the experimental results.Three-dimensional analyses are conducted on the flat and tilted grounds, and compared with the associated experiments. As a result of this, the computed located zones turned out to be consistent with the experimental observation, and the variation of the pulling out strength of the anchor in association with the change of the angle of the slope. In addition, the rotation of the anchor has been observed.Last the simulation of on-site pulling out test was conducted to simulate force vs displacement curves and slide lines on the ground surface.It will be a topic in the future to arrive at more realistic pulling out behaviors through the followings : 1.The improvement of the. analysis program by the implementation of the progressive failure. 2.The evaluation of the heterogeneity of soils.