Study on Rational Design of Ground Solidification Methods as Countermeasures against Liquefaction

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In order to evaluate rationally the tensile strength of cement-treated sands, a series of splitting tests, unconfined tension tests, and unconfined torsional shear tests were conducted and compared. The unconfined tension tests were conducted by using a newly developed testing system, which can transfer tensile force to the specimen through fixing devices by using gypsum as a filling material for the gap between the specimen and its holders. The fixing devices are attached to the top cap and the pedestal through universal joints that are inserted to reduce the bending moment applied unnecessarily to the specimen. As a result, the tensile strength obtained by the unconfined tension tests was larger than the one obtained by the conventional splitting tests, while the unconfined torsional shear tests largely underestimated the tensile strength. Such difference was possibly caused by different extents of progressive failure during each type of tests.In addition, a new plane strain compression testing system suitable for shearing stiff geomaterials and observing shear band formation was developed, and a series of both monotonic and cyclic loading tests were conducted on rectangular prismatic specimens of cement-treated sand. Comparisons were made between monotonic and cyclic plane strain compression tests to evaluate the differences on the peak strength of specimens with and without a cyclic loading history. No evidence of a reduction in the peak strength of specimens subjected to large amplitude cyclic loading was found. To study strain localisation characteristics and their relation with the failure mechanism of cement-treated sand, maximum shear strain distributions were calculated based on digital photographs taken at different stages of loading during each test.