Study on dynamic shear properties of rubber modified calcareous sand with different shapes and contents

Abstract

Calcium sand used in transportation infrastructure foundations is subjected to heavy loading and high speed under dynamic conditions. Utilizing waste rubber materials can mitigate environmental pollution issues and enhance the performance of rubber-modified calcium sand. This study used different waste tire particles and calcium sand as raw materials. Cyclic dynamic simple shear tests were conducted to investigate the liquefaction resistance, dynamic elastic modulus, and hysteresis curve variation of rubber-reinforced calcium sand under cyclic loading. Additionally, the microscopic mechanism was studied in conjunction with particle breakage. The results show that compared to strip-shaped particles, rubber granule reinforcement is more effective in improving dynamic performance and suppressing liquefaction of calcium sand. However, changes in particle size have little impact on performance. At a shear frequency of 0.5 Hz, rubber-reinforced calcium sand exhibits the optimal capacity in mitigating stiffness degradation. As shear displacement amplitude increases, the optimized performance of calcium sand decreases. However, when shear amplitude is less than 0.3 mm, amplitude variation has minimal impact on stiffness. Furthermore, this study proposes an effective model for predicting pore pressure in rubber-reinforced calcium sand under varying rubber content, shear frequency, and amplitude. It also elucidates the microscopic mechanisms by which the addition of rubber improves the mechanical properties and deformation capacity of calcium sand.