Gravel Pile Theoretical Analysis And Engineering Studies Of The Saturated Soft Soil

Gravel pile composite foundation has been largely used in the projects of foundation treatment in the past 20 years of reforming and opening up. Its theory and practice have been improved greatly. But, at the same time, some discordance has been found between the theory and practice result. Especially, when being used in the saturate soft soil condition, some problems as the theory research behind the practice were founded. The conventional theory can not explain the new problem in practice exactly. There has a considerable error between calculated result by formula and actual result. All of these hindered the technical development and economical application of gravel pile composite foundation.Based on theory of gravel pile composite foundation, by a lot of engineering applications and experimental researches of vibration-replacement stone column, a analysis and research theory, on the design, construction inspect and quality test for gravel pile, has been taken forward in the paper.Firstly, several basic characters of soft soil has been introduced, clarified the error of understand for saturate soft soil, introduced the research achievement and character of saturated soft soil in the Zhujiang Delta. And the theory of composite foundation, various methods of foundation treatment and its applicability has been mentioned.Secondly, the formula of bearing capacity and settlement has been discussed. The application condition of formula and its merits and defects, mechanical and stress-strain characters have been analyzed. Combine with character of gravel pile, it has discussed the test method and code for quality of vibration replacement stone column.Thirdly, based on the quality control of construction and information construction, DC-3, a new system for data collection and quality control for vibre replacement stone column, has been introduced. And its work theory, function and effect have been mentioned.At the end, the foundation code and some theory research resultsdoesn't recommend vibration replacement stone column to treatment the saturated soft soil when un-drained shear strength below 20kPa. Through a large number of project practices, it puts forward the feasibility of vibration replacement stone column under this condition. Researched and analyzed the import of quality affection factors such as cushion, pile diameter and pile length by orthogonal test. The amendment formula has been deduced. And some novel viewpoints on application and design of vibration replacement stone column have been brought forward.