Undrained dynamical behavior of Nanjing flake-shaped fine sand under cyclic loading

Abstract

A series of dynamic behavior tests on Nanjing flake-shaped fine sand were performed by using the WFI cyclic triaxial apparatus made in England. The dynamic behaviors of Nanjing flake-shaped fine sand under different static deviator stress levels and cyclic stress ratios were studied. Through comparing the effective stress path under cyclic loading with static loading, the processes of liquefaction of saturated Nanjing flake-shaped fine sand with development of dynamic pore-water pressure, including the initial compact state, compression state and dilative state, were investigated. The variation of the shear stiffness with the number of cycles and cyclic strain was investigated by analyzing the secant shear modulus in each unload-reload loop of dynamic stress-strain relationship. And by means of the exponential function, the empirical equations of the relationship between secant shear modulus G sec , shear modulus ratio G sec /G max and cyclic strain ε were established based on series of test results. The results show that according to different combinations of static deviator stress and cyclic stress, two kinds of failure patterns with deviator stress reversal or no deviator stress reversal are observed in the samples tested in this series, including cyclic mobility and the failure of accumulation residual strain. In addition, the degradation of dynamic shear modulus is due to the development of vibration pore-water pressure and it is observed that the shear modulus reduces with the progressive number of cycles.

Experimental Study on Pore Water Pressure Characteristics of Saturated Silty Sand

“…Dong Shuyun [6] and others analyzed the rules and models of pore water pressure rise in the Yellow River Delta foundation soil. Zhuang Haiyang et al [7][8] and Chen Guoxing et al [9] separately studied the dynamic properties of ne sand in Nanjing, proposed the in uence rules and mechanisms of factors such as rubber membrane effect on the large deformation characteristics of lique ed ow of Nanjing ne sand. Wang Binghui [10] de ned the development patterns of effective dynamic shear stress ratio and logarithmic attenuation rate of effective stress for pore pressure ratio in saturated Nanjing ne sand with respect to cyclic cycle ratios.…”

An investigation on the erosion resistance of rare earths nitrocarburized 40 Cr steel

“…In comparison with other thermochemical process, for example, nitriding, nitrocarburizing has many advantages such as high-permeation rate, shorter treatment time, smaller distortion and higher degree of shape, and dimensional stability [1]. In addition, nitrocarburizing layers have higher impact toughness values comparing nitriding.…”