Study on shear performance of stirrup-encased stone column composite ground
Zhang Ling1,2 Liu Changjie1,2 Zhao Minghua1,2 Ou Qiang1,2,3
1. Colleague of Civil Engineering, Hunan University, Changsha 410082, China;
2. Key Laboratory of Building Safety and Energy Efficiency, Hunan University, Changsha 410082, China;
3. Chongqing University, Chongqing 400045, China
Abstract：The shear performance of the stirrup-encased stone column is very important to the stability analysis of the stirrup-encased stone column composite ground. In this study, a large-scale direct shear test is conducted to study the horizontal shear performance of the composite unit composed of a single stirrup-encased stone column and its surrounding soil. Particular attention is paid to the effect of normal stress, properties of the surrounding soil, and tensile strength of the reinforcement on the shear performance of the composite unit. It is found that the shear strength of the composite unit with a stirrup-encased stone column is greater than that of the one with an unreinforced stone column. The reinforcement effects, such as the increase in the shear strength of the composite unit, shall be more prominent for the comparatively large tensile strength of the reinforcement. For the column being surrounded by sandy soil, the relative density of sandy soil has little effect on the shear resistance of the composite unit. For the column being surrounded by cohesive soil, the shear strength of the composite unit with a stirrup-encased stone column may decrease with the increase of water content of the cohesive soil. In addition, the characteristics of the reinforcement may affect the failure pattern of the stirrup-encased column during shearing. Three different failure modes, namely bulging failure of reinforcement, shear failure of reinforcement and flexure-twist failure of column, may occur in the stirrup-encased stone column in sandy soil. It is also found from the test data analyses that the area replacement method is suitable for calculating the shear strength of the composite unit comprised of the encased stone column and the surrounding soil.
