酸性腐蚀花岗岩冲击荷载能量演化试验研究

Experimental study on energy evolution of granite after acid corrosion under impact loading

化学腐蚀可以对岩体力学性能产生劣化作用,实际工程中的岩体也往往面临钻爆开挖、机械破岩等动态冲击荷载,而岩体的破坏本质上是能量的吸收与耗散过程,研究化学腐蚀后岩体承受冲击荷载作用时的能量演化具有重要的现实意义。利用分离式霍普金森压杆(SHPB)测试系统对两种不同pH值(3和5)的KHSO4溶液浸泡后的花岗岩试样进行动态冲击试验,设定腐蚀时间为30、60 d,另设一组无腐蚀过程的原状试样作为对照,考察0.15 MPa气室压力下酸性环境腐蚀后花岗岩的能量演化效应,得到试样的动态应力-应变曲线、峰值应力、峰值应变、能量吸收率随环境pH值和腐蚀时间的变化规律。结果表明,随着溶液pH值的降低和腐蚀时间的增长,动态应力-应变曲线的非线性段被压缩,峰值应力和峰值应变都在降低。在pH值为3的溶液中腐蚀60 d后,试样的能量吸收率从37.39%上升到52.11%,表明随着化学腐蚀的增强,花岗岩强度降低,变形能力变差,应力波在其内部传播时消耗掉了更多的能量,试样更易破坏。

Chemical corrosion has a degrading effect on the mechanical properties of rock masses.The rock masses in engineering practice is generally facing dynamic impact loading such as drill burst excavation and mechanical rock breaking,moreover,the destruction of rock is essentially a process of energy absorption and dissipation.Therefore,it is of great practical significance to study the energy evolution of corroded rock under impact loading.Dynamic impact tests were conducted on granite specimens after soaking in KHSO4 solutions at 2 different pH values(3 and 5)using the Split Hopkinson Pressure Bar(SHPB)system.Corrosion time was set to 30 and 60 days,and another set of specimens without corrosion was set up as control group,in order to investigate the energy evolution of granite after acidic corrosion under air chamber pressures of 0.15 MPa.The change laws of dynamic stress-strain curve,peak stress,peak strain,and energy absorption rate with pH value and corrosion time were given.It was found that with the decrease of pH value and the increase of corrosion time,the nonlinear stage of dynamic stress-strain curve was compressed,the peak stress and peak strain decreasing.Moreover,the energy absorption rate increased from 37.39%to 52.11%after 60 days of corrosion in solutions of pH=3,indicating that with increase of chemical corrosion,the strength of granite decreased,the deformation ability becoming worse,stress waves consuming more energy as they propagate through the interior of samples and the specimens were more easily damaged.