One-dimension Consolidation Theory And Application Of Double-layered Foundation On Marine Soft Soil

Lianyungang marine soft clay is muck and mucky soil. When the expressway is built in the district, the soft clay foundation is often treated by cement-soil piles. This marine soft clay is of high compression,lower drainage consolidation and poor stability for its roadbed. During engineering construction, the phenomena, as larger settlement deformation, crack and slide, often take place on the embankment. This paper is concerned with the consolidation and project application of the double-layered foundation for Lianyungang marine soft clay treated by cement-soil piles. The main results of the study are obtained as follows:1) In order to analyze and study the physical and mechanical characteristics of Lianyungang marine soft clay deeply, large numbers of basic mechanical characteristics tests and tri-axial shear tests are completed.2) In order to investigate the loaded and failure characteristics of the cement-soil, the cement-soils for the different ratio and different cure time are studied in the laboratory, and their unconfined compression tests and tri-axial shear tests are performed.3) Based on the solution of one-dimension consolidation, the one-dimension consolidation of the double-layered foundation is solved for two-grade loading in virtue of transcendental equation; Simultaneously, the one-dimension consolidation of the double-layered foundation is solved by means of Laplace transform for two-grade loading, and Stehfest numerical transform is applied in Laplace's inverse transformation; Furthermore, according to the practical foundation shapes, the consolidation models of the soil between piles and the substratum are built and solved respectively.4) The effect of each parameters on the consolidation of the double-layered foundation is discussed, and the solution of load transfer method for double-layered foundation is applied in A1-A4 section of Lian-Xu expressway. The results of calculating settlement of the double-layered consolidation theory are basic agreement with the measuring settlement results.