Application Research Of The Soft Soil Foundation Treated With CFG Pile In Highway Engineering

The soft foundations exist universally in highway project. Soft soil has the following features: larger void ratio, higher natural water content, higher compression, lower intensity and higher sensitivity. The foundations which composed of soft soil have the lower ground bearing capacity and larger settlement, which lead to the foundations instability. It should be treated in order to be used as bearing stratum.The engineers have many ways for processing foundation and the methods are already very mature.But how to choose foundation treatment method, so that reliable technology, investment saving, easy construction, is an issue of concern to engineers.CFG pile composite foundation has been applied universally in highway project due to the features such as higher bearing capacity, Lower cost and shorter duration. There are multiple foundations of soft soil in Da Zhu city transit rebuilding project. The thickness of soft soil is from 1.0m to 11.0m which mainly composed by silty clay. It should not be used directly as a natural foundation to bear load. In this thesis, it is discussed around the feature segment K5+335~K5+430 in this engineering. The CFG pile composite foundations will be used for improving the bearing capacity and reducing foundation settlement. It will introduce the development status of composite foundation. It highlights the development process of CFG pile composite foundation and engineering applications. It will describes the project Da zhu State Road rebuilding project, site environment, engineering geological conditions, by analyzing the effects of the practical project in the feature segment, K5+335~K5+430, the treatment of soft foundation and the construction technology. In accordance with existing norms, the effects of composite foundation will be checked for directing the feasibility of the treatment. The finite element analysis software ABAQUS will be used for analysis.The natural foundation of K5+416 section will be used for modeling in order to obtain the value of settlement and foundation bearing capacity by embankment load. These parameters will be obtained the reasons of ground treatment. These factors will be taken into account such as over time, CFG pile composite foundation pile length and area replacement ratio for achieving the influence rules of composite foundation bearing capacity and settlement. The conclusion will provide effective reference for design of composite foundation. Based on the design scheme of K5 + 416 section, the following data including the subsidence and sedimentation rate, horizontal displacement and velocity, stress ratio of pile-soil, composite foundation bearing capacity will be extracted for the feasibility of the scheme. The treatment of soil soft should be verified by the monitoring data which including the detections of bearing capacity and the monitoring data of settlement. And compared with the third chapter finite element calculation results, the rationality of the finite element calculation will be verified. Then it will introduce the design method of controlling settlement and optimal design methods. And it will put forward to the optimization design method of CFG pile composite foundation.In this thesis, CFG pile composite foundations treatment has been applied in the actual engineering and proposed the optimal design methods. The reasons of treatment will be raised. The affecting factors about the settlement and the foundation bearing capacity of CFG pile composite foundation will be obtained. The treatment effect will be verified by numerical simulation method and field test. The research results in this thesis have the important reference vale for similar projects.