CAJ | 학술논문

利用研制的岩石动静组合加载SHPB试验装置,系统研究岩石在一维动静组合加载下的冲击破坏特性.首先按照一维应力波传播理论,对动静组合加载的试验原理进行理论论证.试验过程中预先在轴向施加不同载荷,按照静载强度的20%,30%,40%,70%,80%和90%等6个系列进行,然后沿轴向进行冲击加载,考察岩石的临界破坏承载强度.研究结果表明:在临界破坏的情况下,动态冲击的应力-应变曲线(包括常规冲击和动静组合加载)最后都会出现总应变减小的现象,这是由于冲击过程中岩石内部储存弹性能释放所致.在轴向静压较小时,岩石的组合加载应力-应变曲线跟常规的冲击试验曲线类似;轴压较大时,岩石的组合加载应力-应变曲线没有初始的近似线弹性段,直接从非线性段开始.随着轴向静压的增大,岩石的抗冲击强度呈现出先增大后减小的趋势,大约在静载强度60%时,抗冲击强度达到最大值.在入射能较小时,岩石吸收的能量会缓慢增加,在入射能较高时,岩石吸能会快速增加.常规冲击下岩石的临界破坏模式为劈裂形式,动静组合加载下呈现压剪形式.
이용연제적암석동정조합가재SHPB시험장치,계통연구암석재일유동정조합가재하적충격파배특성.수선안조일유응력파전파이론,대동정조합가재적시험원리진행이론론증.시험과정중예선재축향시가불동재하,안조정재강도적20%,30%,40%,70%,80%화90%등6개계렬진행,연후연축향진행충격가재,고찰암석적림계파배승재강도.연구결과표명:재림계파배적정황하,동태충격적응력-응변곡선(포괄상규충격화동정조합가재)최후도회출현총응변감소적현상,저시유우충격과정중암석내부저존탄성능석방소치.재축향정압교소시,암석적조합가재응력-응변곡선근상규적충격시험곡선유사;축압교대시,암석적조합가재응력-응변곡선몰유초시적근사선탄성단,직접종비선성단개시.수착축향정압적증대,암석적항충격강도정현출선증대후감소적추세,대약재정재강도60%시,항충격강도체도최대치.재입사능교소시,암석흡수적능량회완만증가,재입사능교고시,암석흡능회쾌속증가.상규충격하암석적림계파배모식위벽렬형식,동정조합가재하정현압전형식.
The impact failure characteristics of rock subjected to one-dimensional coupled static and dynamic loads are conducted with a modified split Hopkinson pressure bar(SHPB). Firstly,the testing principle with axial precompression stress is re-examined based on one-dimensional wave theory. The axial precompression stress(in accordance with the static load strength of 20%,30%,40%,70%,80% and 90% in six series) is loaded on rock specimen before the axial impact loading is carried on,and the critical dynamic strength is obtained and studied respectively. The results show that in the case of critical damage,the total strain on all stress-strain curves (including the conventional impact testing and impact testing with coupled loads) will reduce finally. The reason for this phenomenon can be explained by the release of stored elastic energy of rock in the process of impact. When axial precompression stress is smaller,the stress-strain curves of impact testing are similar. When axial precompression stress is larger,there is no initial linear elastic part in the curves of impact testing with coupled loads. The dynamic strength increases with the increase of axial precompression stress and the maximum impact strength can be obtained when 60% static strength is precompressed. The absorption of energy increases slowly when the incident energy is smaller and will increase quickly when incident energy is larger. Rock specimen will break with shear failure model subjected to one-dimensional coupled static and dynamics loads,while failure mode will be splitting faulting for conventional impact testing.