直达波和反射波在地层中的传播规律研究

Study on Propagation Law of Direct Wave and Reflect Wave in Formation

研究地震波在地层中的传播规律对于工程地震勘探具有重要的意义。采用离散元方法建立了无节理岩体和含一条节理岩体的数值计算模型,分析了直达波和反射波在地层中的传播衰减规律及两者之间的关系。相比无节理岩体,含一条节理岩体具有明显的反射波;直达波的频带宽度随爆源距离的增大而变窄,直达波在地层传播过程中,高频成分损失严重,保留了低频成分;相比直达波,经过衰减后的反射波频带能量分布较均匀;爆源距离大于一定值后,直达波和反射波的振动主频趋于稳定;直达波振动能量越大,反射波振动能量越大。

Study of the propagation law of＇ seismic in the fi）rmation tlas great significant tor engineering seismic exploration. Numerical model of rock mass with none joint and one joint are established by using discrete element method. The propagation law of direct wave and reflect wave, and the relationship of both are analyzed. Compared with rock mass with none joint,there is obvious reflect wave about rock mass with one joint. The bandwidth of direct wave became narrow with increase of distance of explosion source. High frequency components suffer serious loss and low frequency components are preserved in the propagatinn process of＂ direct wave. Compared with direct wave, fre- quency band energy of reflect wave by attenualinn is well distributed. Main vibration frequency of direct wave and re- flect wave are tended to be stable when the distance of explosion source is beyond a certain value. The bigger vibra- tion energy of direct wave, the larger vibration energy of reflect wave.