Analytical Study On Correlative Problems Of Composite Foundation

This article obtained the thixotropy law of the saturated silt clay by the three-axis shear experiment, and the law is used in the elastic analysis of bearing capacity of the discrete pile. Meanwhile, use the Berrum formula and the Shear -Deformation method to calculate the side friction of pile and the soil deformation around pile respectively, then the stress ratio between pile and soil and the effective pile length of DJM pile composite foundation is studied according to the displacement coordination between pile and soil and engineering practice. The results can be gained as follows:(1) The bearing capacity of the discrete pile is a critical parameter in the design of compound foundation. Generally, discrete pile often occur swelling destroy, there is no computation model considering thixotropy law of the saturated silt clay currently. The calculating formula of the bearing capacity of discrete pile is deduced through elastic theory. It provides engineering personnel new method to design bearing capacity of the discrete pile in Handan.(2) Simplified distribution of side friction of flexible pile can be got through lots of theoretical investigation and the results of field measurement of composite foundation. Use the Shear -Deformation method to calculate the soil deformation around pile. The formula of effective length of DJM pile composite foundation is deduced through displacement coordination between pile and soil.(3) Use the Berrum formula to calculate the side friction of DJM pile. The formula of stress ratio between pile and soil is deduced through displacement coordination between pile and soil. The formula is modified through relationship graph of pile-soil stress ration and thickness of cushion and load got from static loading testing results of composite foundation in Handan. Then the formula suitable to Handan can be got.Three formula deduced in this article is characteristically local. They offer some reference value for designing DJM pile composite foundation and discrete pile composite foundation in Handan.