Study On Technique For Soft Grand Treatment On Waterway Cut-off And Dike In The Pearl River Delta

The soft clay with high water content, high void ratio and small strength distributs extensively in the Pear River Delta. The characteristics of the Pear River waterway is narrow width, large depth, winding path, as a result that Cut-off and Dike and embankments are widely used in the waterway training. However, waterway treatment on soft grand is lack of studies, it is necessary to make a systematic study and summarization.The engineering properties of the soft clay in the Pear River Delta were analized from the aspects of formation, micro-structure and the physical mechanical properties. The differences between engineering of waterway Cut-off and Dike and engineering of harbor storage yard and embankment were studied. Moreover, the method of foundation treatment on soft clay in waterway Cut-off and Dike were summarized. Based on the Xijiang waterway training project, valuable results of treatment on soft grand were obtained.The practice of the Pear River waterway training indicates that natural sloping in Cut-off and Dike could be chosen for field available. On the contrast, stiff or vertical shore protection must be used as a cautious choose with limited field. Vacuum method of preloading is one of economic ways of soft grand treatment. At the same time, gravel piles, mixing piles, and spiral spray piles can be used to strength soft grand of shore. But more attention must be paid to the influence caused by construction factors, and field test with these three treatments are used.Based on field test, construction parameters of gravel piles in soft clay, shear strength index of gravel piles with big grain diameter were determined. The criterions and methods for inspection of gravel piles were provided. As indicated by the research of mixing piles, the shaft-strength would be influenced by soil characters, water content and organic content. The mixing piles have low shaft-strength and small increment when the soil has high contents of clay, water and organic. And excess pore water pressure is caused by construction of mixing piles in a certain scope around of piles.