Study On Consolidation Theory For Saturated Soil Based On The Centrifuge Model Test

The geotechnical centrifuge model test is not only one important experimental tool in the current field of geotechnical engineering, but also the best similarity model test in various types of physical model test. Centrifuge model test technique is adopted to simulate gravity field by changing centrifugal acceleration, in order to simulate the related conditions of many geotechnical structures. Whether saturated soil consolidation theory is applicable by changing centrifugal acceleration and the hight of test model under the effect of high centrifugal force field, which is directly related to the reliability of test results in the centrifugal force field. View of current research of centrifuge model test technique, firstly, through a systematic experimental research and theoretical analysis, the applicability conditions of consolidation theory in the centrifugal force field were researched. Then the time scale of consolidation was amended. And consolidation behavior and engineering characteristics of regional soft soil were studied.The main research work is as follows:1. Centrifugal consolidation model test device was designed in the centrifuge model box, which can be reasonably used in consolidation behavior of regional soil studies in the centrifugal force field. At the same time, the test device can effectively reduce side friction of the experimental device and the impact of the experimental results by the consolidation discharged water. And then experimental error due to uneven distribution of centrifugal acceleration on the model was reduced.2. Under the conditions of different centrifugal acceleration, the saturated sand was analyzed by one-dimensional consolidation tests. Based on the research on the soil settlement process of consolidation test curves with time and pore water pressure variation curve with time, and comparative analysis of the time of consolidation tests and theoretical, it was found that even in the low centrifugal force field of5g, one-dimensional consolidation theory was not used to analyze the characteristics of saturated sand test. For the inviscid saturated pure sand, because the water flow velocity in the soil particles is too fast, the water flow show turbulent flow state and don’t meet the Darcy’s law. In the centrifuge model tests, the application of Terzaghi one-dimensional consolidation theory is limited. 3. For typical saturated soft soil in different regions, in different centrifugal acceleration field, the centrifugal consolidation model tests were carried out. Through the comparative analysis of numerical calculation and theoretical, applicability conditions of soft soil consolidation theory in centrifuge model test was proposed, and reasonable limits of centrifugal acceleration was given.4. Through the comparative analysis of multiple sets of centrifuge model test time and calculated time for soft soil on typical area, uneven distribution of centrifugal acceleration on the model had a greater impact on the results, and Terzaghi one-dimensional consolidation theory was not applicable to the test in centrifugal force field. In the centrifugal force field, the impact of soil weight must be considered, Gibson one-dimensional consolidation theory was recommended for calculation of test results.5. On the basis of a large number of centrifuge consolidation model tests and large-strain consolidation theory, combined with previous research, based on potential energy of soil water system, Darcy-theory, theoretical mechanics and the mechanical characteristics of soil in the centrifugal field, time scale correction formula of centrifuge consolidation test was derived. Through the centrifuge consolidation model tests of the saturated soil in different regions were studied, given the range of time scale correction factor.6. Based on the project of Hangzhou-Ningbo Expressway and Pucheng-Weinan Expressway, respectively, for saturated soft clay and loess, the centrifuge tests of simulation of actual working conditions and numerical calculations were compared, and introduced in the corresponding experimental time scale modified. And the feasibility of correction formula is validated by centrifugal model test of saturated basic theory and the engineering.