冻融循环作用下花岗斑岩动载强度研究

 对冻融前后的花岗斑岩进行相关静态、动态力学试验，获得岩样不同冻融次数下的弹性模量、泊松比、单轴抗压强度、抗拉强度及冲击动载应力～应变曲线。在Holmquist-Johnson-Cook(HJC)本构模型参数分析的基础上，对经历不同冻融次数的花岗斑岩进行SHPB试验模拟。结合室内试验数据与数值模拟计算结果，分析花岗斑岩动载强度与应变率及冻融次数的关系。研究结果表明：岩样冻融前后动态应力～应变曲线形态有所区别，SHPB试验的反射波和透射波形态发生明显变化，相同入射波情况下试样产生不同的应变率；SHPB试验数值模拟结果与实测值吻合较好，得到的不同冻融次数下花岗斑岩HJC模型参数是可靠的，数值模拟与室内试验相结合是研究分析的有效方法，二者优势互补；花岗斑岩动态强度受冻融次数与应变率共同影响，其影响效应相反，相互耦合。岩石冻融循环作用下的动载强度研究是一项重要课题，是冻融损伤条件下岩石动态本构关系研究的基础，对解决寒区露天边坡稳定性问题具有重要意义。

STUDY ON DYNAMIC STRENGTH OF GRANITE PORPHYRY UNDER FREEZE-THAW CYCLES

Elasticity modulus，poisson ratio，uniaxial compressive strength，tensile strength and dynamic stress-strain curves of granite porphyry were obtained under freezing-thawing cycles utilizing the relevant static and dynamic mechanics experiments. On the basis of HJC model parameters analysis，numerical simulations of the SHPB tests were made utilizing LS-DYNA finite element software. According to the results of numerical simulations and experiments，the relationship between the dynamic strength with the strain rate and the freeze-thaw cycles were obtained. The results show that：Shape of the stress-strain curves，the reflected and transmitted waves before and after freeze-thaw is different. Samples have different strain rate with the same incident wave under freeze-thaw cycles. SHPB experiment numerical simulation on the basis of HJC model parameters is reliable. Numerical simulation and laboratory test can complement each other. The dynamic strength is associated with the strain rate and the freeze-thaw cycles，but the influential effects are opposite and interconnected. Study on the dynamic strength of rock under freeze-thaw cycles is the basis of dynamic constitutive relation under freeze-thaw damage and has great significance for analyzing the slope stability of open-pit mining in seasonal frozen region.