[工学]岩石力学 3 rock dynamics.ppt

岩石力学 Rock Mechanics 建筑工程学院土木工程系 School of Civil Engineering and Architecture Zhejiang Sci-Tech University China 粘弹性波: 在非线性弹性体中传播的波，这种波，除弹性变形产生的弹性应力外，还产生又摩擦应力或粘滞应力。 塑性波: 应力超过弹性极限的波。 冲击波: 如果固体介质的变形性质能使大扰动的传播速度远比小扰动的传播速度大，在介质中就会形成波头陡峭的、以超声波传播的冲击波。 3) 在固体中可传播的弹性波可分为两类 （1）体波：由岩体内部传播的波(2类） 　　（a）纵波（又称：初至波、Primary波） 质点振动的方向和传播方向一致的波 它产生压缩或拉伸变形。 （b）横波（又称次到波、Second波) 质点振动方向和传播方向垂直的波 产生剪切变形。 （2）面波：仅在岩石表面传播。 质点运动的轨迹为一椭圆，其长轴垂直 于表面，这样的面波又称为瑞利波。 面波速度小于体波，但传播距离大。 Seismic waves Seismic waves are waves that travel through the Earth, most often as the result of a tectonic earthquake, sometimes from an explosion. Seismic waves are also continually excited by the pounding of ocean waves and the wind. Seismic waves are studied by seismologists, and measured by a seismograph, which records the output of a seismometer, or geophone. For seismic studies of oil reservoirs, hydrophones may give additional information. Types of seismic wave There are two types of seismic waves, body waves and surface waves. Other modes of wave propagation exist than those described in this article, but they are of comparatively minor importance. An excellent audience demonstration for seismic waves is shown in slinky seismology. Body waves Body waves travel through the interior of the Earth. They follow ray paths bent by the varying density and modulus (stiffness) of the Earths interior. The density and modulus, in turn, vary according to temperature, composition, and phase. This effect is similar to the refraction of light waves. Body waves transmit the first-arriving tremors of an earthquake, as well as many later arrivals. There are two kinds of body waves: primary and secondary. P waves (primary waves) are longitudinal or compressive waves, which means that the ground is alternately compressed and dilated in the direction of propagation. In solids, these waves generally travel almost twice as fast as S waves and can travel throug