钙质砂的SHPB实验技术及其动态力学性能

开展了11组南海钙质砂和福建石英砂的分离式霍普金森压杆（SHPB）实验，试样相对密实度为90%，厚度分别为10、30和50 mm，得到了冲击荷载下钙质砂和石英砂的应变率时程曲线、应变时程曲线和应力应变关系。实验结果表明：通过严格装样技术可以减小实验设备产生的误差，改变试样厚度、子弹长度、整形器等是实现钙质砂应力平衡和恒应变率的主要手段。在相同的密实度和加载条件下，钙质砂的体积模量和剪切模量约为石英砂的10%，压缩强度和抗剪强度约为石英砂的30%。冲击荷载作用下钙质砂的动态力学性能与石英砂存在较大的差异，因此不能将已有石英砂的研究结果直接用于钙质砂。

Experimental techniques of SHPB for calcareous sand and its dynamic behaviors

This paper conducted 11 split Hopkinson pressure bar (SHPB) tests on the calcareous sand sampled from a calcareous reef in China and silica sand sampled from Fujian Provence of China. The relative density is 90%. The strain-rate history, strain history, and stress-strain curves were obtained for sand specimens with three thicknesses including 10 mm, 30 mm and 50 mm. It is found that test error can be reduced by standard procedure in sand preparation. The stress equilibrium and constant strain rate can be achieved by changing the thickness of specimen, the length of striker and the pulse shaper. With an identical relative density and loading condition, the volumetric modulus and shear modulus of calcareous sand is approximately 10% of the silica sand; and the strength of the calcareous sand is approximately 30% of the silica sand. Therefore, the results of existing silica sand can not be directly applied to calcareous sand because of their large discrepancies.