One Dimensional Consolidataion Behaviour Of Structured Soil And Negative Skin Friction

Since the soil structure characteristic is an intrinsic determinative factor of soft clay engineering property, it is necessary that experiment and theory research on the soft clay structure characteristic be carried on in order to explain the consolidation settlement property of the soft clay ground. Soft clay extensively distributing near the littoral in Southeast China, and pile foundations are in common use in improving the soft ground of large-scale engineering buile in this area. Negative skin friction will develop whenever the adjacent soil settles more than the pile.The magnitude of downdrag can be quite significant. In this dissertation, the study of one dimensional consolidataion behaviour of structured soil and evaluation of the distrubance effect and behaviour of negative skin friction should be based on the study of structured soft clay in order to guide the practice in reason.First, the engineering characteristics of natural clay and the research actuality are introduced. Based on the results of laboratory tests of Wenzhou clay, the relation between structure character and mechanical properties of structured soft soil is examined. The different compressibility of undisturbed soil and remolded soil is compared, and the effect of the rate of loading on the compressibility is analyzed. The method to predict the virgin compressibility curve is introduced.Second, according to the compressibility of structured soft soil ,a method to predict the field compression curve of disturbed soil is developed. Based on the general analytical solution and iterative methods available for the problem of one-dimensional consolidation of layered soils, the semi-analytical solution for one dimensional non-linear soil consolidation considering the structure and self-weight is presented. The computed results about the pore pressure and the degree of consolidation demonstrate the difference between the behavior of undisturbed and disturbed structural soft soils. The corresponding governing equation are presented, in which the influences such as time dependent loading, layered soils and actual overburden pressure are taken into consideration. The behavior of layered structured soft soil under time-dependentloading is discussed.Finally, The solution for negative skin friction based on the solution of layered structuredsoft soil consolidation considering the characteristic of K0 and Poisson ratio is presented.Then, the behavior of negative skin friction is discussed. Lastly ,The study result of tests of negative skin friction are introduced, the influence of the construction technology on negative friction is proposed.