Large-scale dynamic triaxial tests on saturated gravel soil in Nanning metro area
MA Shao-kun;WANG Bo;LIU Yin;SHAO Yu;WANG Hong-gang;WANG Yan-li;College of Civil Engineering and Architecture, Guangxi University;Key Laboratory of Disaster Prevention and Structural Safety, Guangxi University;Guangxi Xinfazhan Communications Group Co., Ltd.;Guangxi Road and Bridge Engineering Group Co., Ltd.;Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Yangtze River Scientific Research Institute;
The gravel soil in Nanning metro area is taken as the research object, and a series of large-scale drained dynamic triaxial tests are conducted on saturated gravel. The effects of the relative density, dynamic stress amplitude and number of loading cycles on the accumulation strain, stress-strain hysteresis loops and pore pressure of saturated round gravel are analyzed. The experimental results show that when the dynamic stress amplitudes are small, the curves of accumulated axial strain with number of loading cycles are stable with the increasing rule of hyperbolic function. A linear relation between the parameter α in the hyperbolic function and the relative density Dr is found. However, the curves exhibit failure type and the increasing rule conforms to power function under a large dynamic stress amplitude. The stress-strain hysteresis loops of saturated round gravel exhibit double-lined type. When the dynamic stress amplitude is small, with the increasing number of loading cycles, the area of hysteresis loops firstly increases and then decreases, the secant modulus firstly decreases and then increases, and the pore pressure firstly increases and then decreases. In the later period of cyclic loading, the pore pressure is high when Dr=0.5 in comparison to the situation Dr=0.3 or 0.7, and this result relates to the gravel breaking characteristics at different initial relative densities.