Theoretical And Experimental Study On In-situ Test In Sand

The characterization of geotechnical parameter such as relative density, strength, and deformability parameter are very important for sand foundation. Because of the lack of cohesion, it is essentially impossible to obtain undisturbed samples in sand, and the results are not reliable, the cone penetration test (CPT) is by far the most common in situ testing method for characterization of granular soils due to its specific advantages such as fast operation, relative low cost, the correlation among the cone resistance and geotechnical parameter for sand can established. The correlation among the cone resistance and geotechnical parameter for sand is analysis in this paper through theoretical and experimental study, boundary condition and size effect for calibration chamber test are also analyzed, an approach uses a weighting scheme that relates sand compressibility is used to calculate relativity density from cone resistance. The main contents of the paper are as follows:1. To obtain the correlation between cone resistance and geotechnical parameter for sand, the process of cone penetration test is divided into 2 phases, cylindrical expansion and soil rotation near the cone. In the cylindrical phase, the limit pressure of cylindrical expansion can be derived from cavity expansion theory, and then using the stress rotation theory, the limit pressure of cylindrical expansion can be related to cone resistance. The relation between cone resistance and geotechnical parameter can be derived.2. According to the indoor experimental date, the correlation among the cone resistance, relative density, stress and over consolidation ratio can be established. The pertinency between correlation and experimental date be analyzed.3. Through indoor simulated test, the influence of boundary condition, size effect, radius ratio, stress state and relative density on cone resistance be determined.4. Based on friction ratio, the compressibility of sand is divided into three level of low, medium and high compressibility. The compressibility is evaluated by fuzzy sets theory. An approach uses a weighting scheme that relates sand compressibility is used to calculate relativity density from cone resistance, the results computer from...