Effects of particle-size distribution on buffering mechanism of waste concrete aggregate cushion layer under impact load
SU Yuchen1, LI Pengfei1, ZHONG Heng1, WU Lin1, WANG Yuan2, LYaru1
1. College of Mechanics and Materials, Hohai University, Nanjing 211100, China;
2. College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
Abstract：Granular cushioning layer installed at top of concrete shed can effectively reduce boulder impact force and transmitted load. To study the effects of particle-size distribution on cushioning performance of waste concrete aggregate cushion, boulder impact tests and three-dimensional discrete-element-numerical simulations were carried out. The results show that for cushioning layer with same particle size, when normalized particle size (d50/R) increases from 0.15 to 0.75. Due to reduction of potential points of failure in shorter force chains, the force chains stability increases. It further limits the particle rearrangement mechanism (average particle movements and rotation angles are reduced by 41.3 % and 33.7 %, respectively) during boulder impact. The peak values of the boulder impact force and transmitted load increased by 36.3% and 282.2%, respectively. For composite particles group, when non-uniformity coefficient (Cu) increases from 1.1 to 8.0, the porosity around coarse particles were filled with finer particles, the coordination number increases and force chain stability was enhanced (average translation distance and rotation angle were reduced by 22.4% and 45.3%), The peak values of boulder impact force and transmitted load increased by 26.0% and 174.6%, respectively, the cushioning performance of cushion decreased. Based on the experimental and numerical simulation results, a cushion reduction coefficient α related to the median of uniform particle size (d50/R) and non-uniformity coefficient (Cu), and the semi-empirical formula of drop hammer impact force considering protective effect of cushion was established. It may further provide technical and theoretical guidance for mountain shed tunnel engineering design.
苏宇宸1，李鹏飞1，仲恒1，吴琳1，王媛2，吕亚茹1. 冲击荷载下颗粒级配对废弃混凝土骨料垫层缓冲机理影响研究[J]. 振动与冲击, 2024, 43(9): 18-26.
SU Yuchen1, LI Pengfei1, ZHONG Heng1, WU Lin1, WANG Yuan2, LYaru1. Effects of particle-size distribution on buffering mechanism of waste concrete aggregate cushion layer under impact load. JOURNAL OF VIBRATION AND SHOCK, 2024, 43(9): 18-26.
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