关键词: 循环单剪, 大尺寸试验, 土动力特性, 土工格室加筋, 橡胶砂

Abstract: Cyclic simple shear test (CSST) is one of the most appreciative methods for studying the dynamic characteristics of soil in earthquake site. To minimize the size effect in the experiment and to monitor the dynamic properties of fiber-reinforced and coarse-grained soils, a testing system called large-scale CSST apparatus is developed. In the developed equipment, the vertical loading plate at the top of the specimen is constrained by a series of vertical linear guides so that it can translate vertically, the horizontal loading plate at the bottom of the specimen is constrained by a series of horizontal linear guides so that it can only translate horizontally, and the shearing box containing specimen is formed by laminated steel rings which are interlayered at four discrete bearing ears with rubber membrane. These features of the equipment ensure proper boundary conditions of the soil specimen during testing similar with soil element in seismic site. The developed CSST equipment is used to perform experiments on geo-cell reinforced rubber sand mixtures. It is shown that the relationship between the dynamic stress and dynamic strain of the specimen exhibits typical hysteresis, nonlinearity and ratchet characteristics, and the - curves and - curves gained from large- scale CSST show similar characteristics as those gained from normal size CSST, implying that the device works well; the differences of the dynamic shear modulus properties between results of large-scale and normal size CSSTs coincide with size effects of CSST; no obvious regularity of size effect on damping ratio is observed from the tests.

Key words: cyclic simple shear, large-scale test, soil dynamics, geo-cell reinforcement, rubber soil mixture (RSM)