Penalty Element And The 3-D Contact Interface Element Are Applied To The Interaction Of Pile Groups-Soil-Pile Cap

In studies of interaction among pile, platform that above it and surrounding soil, this paper employ the concept of plate element to simulate the loading character of platform, and employ the concept of solid element to simulate the character of pile and soil, using the finite element method after understanding the geometry properties of pile, soil and the platform. Analyzing the loading properties of the three entities above and their deformation, this paper also employ a special element, Penalty Element. The introduction of penalty element of this kind has served to guarantee the join harmony of displacement between solid element and plate element, thereby effectively resolving the join problem between platforms, pile that support it and surrounding soil.Considering significant property difference between pile material and its surrounding soil, there may be much shear stress on their contact interface produced under vertical load, thus causing displacement or fission. Therefore it is necessary to adopt one special constitutive law of this kind of contact interface, which can reflect its feature of loading and deformation thoroughly. On the basis of the deformation feature and constitutive laws of some contact interface obtained by Zhang Dongji and people concerned through some single-shear experiments on contact interface between structure and soil, this paper employ one pile-soil three-dimensional constant thickness contact interface model to simulate the " slide" taken place on the interface between pile and its surrounding soil. With this kind model, this paper has also created one finite element model, which can be applied to perform finite element calculation and analyze the pile-loading feature, and deduced its element stiffness matrix.The paper complies and debugs (The Finite Programs of Pile-Loading Feature} .With the field geological draft, the paper studied all-around some effects on the basis of simulating soil to homogeneity soil, for example, pile length, pile long-diameter ratio, pile quantities, pile spacing and so on, on its P-S curve, its bottom displacement, pile head reaction and so on curves.In addition to carrying out studies above, the paper also compiles several auxiliaryprograms. One of the aims is to resolve soil distribution featured by layer. Another is to deal with the conjunction between data compiled and obtained by SAP software and input data program, thus saving a lot of time spent in pre-process.