不耦合装药爆破对硬岩应力场影响的数值分析

爆破地震勘探石油是一种重要的方法，但爆破地震效应与爆破参数、地质条件等密切相关。采用动力有限元软件ANSYS/LS-DYNA，对柱状炸药与药孔壁之间为空气或其他介质以及空隙间距变化时碳酸盐岩岩石中爆炸应力波的传播规律和爆炸地震波能量的衰减特性进行了数值模拟研究，得到了不耦合装药爆炸时岩石应力、振动速度的衰减规律以及与不耦合系数、间隙介质的关系，分析了不耦合效应对爆炸地震波能量的影响。研究表明，不耦合或耦合不好时会使岩体中爆炸应力波的强度大大降低；耦合状态对岩体应力及速度的衰减系数和衰减指数影响较大；在空隙中注水或灌满泥浆会改善它们的耦合关系，增大下传的爆破能量。所得成果可为我国西南地区优选适合碳酸盐地层地震勘探的激发因素提供技术途径和方法。

Numerical analysis of influence of uncoupled explosive-charge structure on stress field in hard rocks

Petroleum exploration with blasting seismic waves is an important method at present. But blasting seismic effects are influenced by blasting conditions and media around. Propagation rules of blasting stress waves and attenuating characteristics of blasting seismic waves in carbonatite rock are analyzed by numerical simulation with ANSYS/LS-DYNA software. The space between cylindrical charge and rock is filled with water or other media and the dimension of interspace changes. Five kinds of interspace and three types of media are considered. Attenuating characteristics of stress and velocity of rock under uncoupled explosive-charge detonation are obtained. The relationship between stress or velocity and uncoupling coefficient or media is put forward. Uncoupling effects on strength of blasting seismic waves are analyzed. It is shown that uncoupling or bad coupling of explosive and rock can weaken the strength of stress waves. Water or slurry can improve coupling relationship of explosive and rock and make more blasting energy propagation downward. The conclusions will be a good reference to select a proper method to seismic exploration in China’s southwest region.