花岗岩残积土动态冲击性能的SHPB试验研究

为研究花岗岩残积土的动态冲击性能，开展了高速冲击下的分离式霍普金森压杆（SHPB）试验，与常规应变率下的试验结果比较，分析了高应变率对花岗岩残积土的应力?应变特性和强度的影响。结果表明：低、高应变率下的花岗岩残积土的?-?a（轴向应力?轴向应变）曲线均呈现出软化型。随着应变率 增加，?-?a曲线向?a增大的方向移动，破坏应变?af增加。但高应变率下?af增加的程度更加明显。花岗岩残积土的峰值强度普遍具有应变率依赖性，二者可用直线关系拟合，但低、高应变率下的拟合关系并不一致。提出了率敏性因子m定量评价依赖性强弱。研究发现，随着应变率的提高，强度的应变率依赖性减弱，低应变率下的m为26.694，而高应变率下仅为0.013。相关试验结果指出，高速冲击荷载对土体总体有害。工程中应该采取合理措施控制冲击荷载的危害。该研究有助于深化花岗岩残积土动态冲击性能的理解，为相关工程的施工与设计提供技术参考。

SHPB tests on dynamic impact behavior of granite residual soil

Split Hopkinson pressure bar tests (SHPB) were carried out to investigate the strength characteristics of granite residual soil under high strain rates comparing to that under common strain rates. Stress-strain curves and strength properties under various strain rates were obtained and found to be strain-softening. The failure strain ?af increased with increasing the strain rate. The increase of ?af was more evident at high strain rates. The peak strength of granite residual soil was found to be rate-dependent, and the peak strength increased linearly with the increase of strain rate, but the fitting relationships under low and high strain rates were different. The coefficient of strain rate sensitivity m was proposed for the quantitative evaluation of the correlation. The results show that the dependence decreases with the increase of strain rate. The value of m at low strain rate is 26.694, while only 0.013 at high strain rate. Judging from the test results, the high-speed impact load is generally harmful to the soil. The research will lead to a deeper understanding of the impact damage mechanism and provide technical guidance for relevant construction.