Study On Compacting Effects Of Jacked Pile In Layered Ground And Its Prediction And Prevention

The obvious compacting effects caused by the penetration of jacked pile may have severe influence on surrounding engineering environment. So it is important for engineering application that compacting effects of jacked pile are effectively predicted and meseaures that can decrease the compacting effects of jacked pile are taken. This paper firstly recites and analyzes the researching methods of compacting effects, and points out their advantages and disadvantages in detail. Then based on the above analyses, some main original work are made as follows.1. A two-dimensional axisymmetric finite element model which accords with actual process of jacked pile is established, and displacement penetration method which is more reality and has the effect of animated simulation is applied. So the following problems are solved including finite deformation problem, contact nonlinear problem, elastoplastic constitutive law, consuming time of computer, foundation's initial geostatic pressure field.2. Compacting displacement field and compacting stress field in homogeneous soil during and after single pile construction are simulated and analyzed. And the effects of displacement fields are put forward in detail caused by different modulus ratio, friction between pile and soil, possion ratio of soil, soil index of c and Φ, friction between pile and soil, considering foundation's initial geostatic pressure field or not.3. Compacting displacement field and compacting stress field in layered ground are simulated and analyzed in detail. Following conclusions are pointed out: (1) the harder soil layer will be pushed into the softer soil layer which is lied above or beneath it. (2) the horizontal displacement near the boundary between the harder soil layer and the softer soil layer will increase abruptly. (3) the horizontal stress discontinuity at the boundary will happen.4. Several conditions' compacting displacement field and compacting stress field which involve transversely isotropic soil , soil's dilation, two-line-piles under plane strain condition, considering pile machine's role, excavating an anti-compacting groove are simulated and analyzed in detail. It is put forwad that because of the harder soil layer's existence more tensile stress will appear in pile body and the pile body will bend repeatly and be prone to crack or break even.