Development of finite element code for assessing large deformation problems with ALE

静力触探被广泛应用于地基勘察。然而，侵彻过程的机理一直没有得到合理的解释，因为该问题是锥体周围大变形最困难的边值问题之一。欧拉有限元方法已成功地应用于圆锥侵彻过程的分析。如果将材料位移增量与网格点位移增量分开，则可以避免单元变形的问题。讨论了它在粘土和砂岩中的性能。对粘土进行了不排水分析，因为粘土沉积物中的贯入过程可以认为是完全不排水条件下的现象。以金凯湾现场的CPT为例，验证了CPT在粘土沉积物中的计算效果。另一方面，选择了东小岛再生砂矿和克米川更新世砂矿作为砂矿的代表。与粘土沉积情况不同，砂土沉积的贯入过程满足充分排水条件。在数值计算中还引入了剪胀效应。对于粘土和砂岩，计算结果均能较好地描述原地锥尖阻力，并显示了由于贯入引起的锥体周围显著的应力积累和大应变。此外，即使在砂子等摩擦材料中，塑性变形的影响区域也局限在圆锥轴附近。

CPT is widely used for subsoil investigation. However, the mechanism of penetration process has not rationally been explained because this problem is one of the most difficult boundary value problems with large deformation around cone. Eulerean finite element method has successfully been applied to the analysis of the process of cone penetration. The problem with respect to the element distortion can be avoided if the material displacement increments are uncoupled from the grid point displacement increments. Performance in clay as well as sand deposits is discussed. Undrained analysis was used for clay based on the fact that the process of penetration in clay deposits can be considered as a phenomenon under perfectly undrained condition. In-situ CPT at Kinkai Bay site was selected to validate the calculated performance for CPT in clay deposit. On the other hand Higashi Ogishima reclaimed sand deposit and Kemigawa Pleistocene sand deposit are selected as representatives for sandy deposits. Far from the case of clay deposit, fully drained condition is satisfied for the process of penetration in sandy deposit. Dilatancy effect is also introduced into the numerical assessment. For both clay and sand deposits, the calculated performance can describe the in-situ cone tip resistance well, and shows the significant stress build-up and large strain around cone due to penetration. Furthermore, even in the frictional materials such as sand, the affected area in terms of plastic deformation is found to be localized in the vicinity of cone shaft.