基于异向波速模型的微震定位改进  

Improvement of microseismic location based on an anisotropic velocity model

作　　者：戴峰[1] 郭亮[1] 徐奴文[1,2] 樊义林[3] 徐剑[3] 姜鹏[1] 

机构地区：[1]四川大学水力学与山区河流开发保护国家重点实验室,成都610065 [2]山东大学土建与水利学院,济南250061 [3]中国长江三峡集团公司,北京100038

出　　处：《地球物理学报》2016年第9期3291-3301,共11页Chinese Journal of Geophysics

基　　金：国家重点基础研究发展计划(973计划)项目(2015CB057903);国家自然科学基金项目(51374149;51679158)资助

摘　　要：针对波速分层的区域岩体,在异向波速模型的基础上,对垂向上的应力波按岩体波速值大小作分段区别,推导震源应力波走时关系式,建立分层速度定位目标函数,基于此提出一种由参数准备、层速度反演、微震定位三个模块组成的分层速度定位模型SV,并采用遗传算法进行优化求解.然后,对分层速度定位模型在已构建微震监测系统的白鹤滩水电站左岸岩质边坡进行验证.微震事件重定位结果表明,分层速度定位模型定位微震事件的最大、最小和平均偏离层内错动带程度指标较单一速度模型分别降低了57.17%、36.51%和57.35%,证明了定位模型在波速分层的区域岩体微震定位应用中比单一速度定位模型更加合理可靠.As a kind of three-dimensional detection of seismic events,microseismic（MS）monitoring techniques have been widely used in the world for many years to assess the stability of surrounding rock.The location of MS events is foundation of MS monitoring.Resulting from anisotropy and inhomogeneity of regional rock masses,the velocity of stress waves may be different in different directions and areas.So,it is difficult to figure out a reasonably accurate location.Aimed at the regional rock masses with stratified velocities,a simplified and stable stratified velocity location model（SV）is proposed.The SV model is proposed based on the anisotropic velocity model,which simplifies the propagation path of stress waves into a straight line,which consists of horizontal and vertical velocities,that is,one for underground sensors and the other for surface sensors.Taking into account that the vertical stress waves pass through some rock formations at different velocities,the model is constructed part by part according to the values of each interval velocity.The first thing is to derive the nonlinear equation of stress wave travel time by spatial analytic geometry′s operation and analysis.The target function of SV is established by using L2 norm of the timeresidual between the measured value and calculated value of the travel time difference of each two sensors.Secondly,based on the established target function,the SV is proposed,which consists of parameters-preparation module,interval velocities inversion module and seismic location module.In the parameters-preparation module,the regional rock mass is divided into some wavevelocity layers according to engineering geological data.And,using spatial analytic geometry′s operation and analysis,the analytical expressions for layer interfaces are derived.In the interval velocities inversion module,the target function to solve velocities is figured out according to the form of the target function of SV.Then we collect some blast events or rockburst with known coordinate values.U

关 键 词：微震监测 异向波速模型 分层速度定位模型 遗传算法 岩质边坡 

分 类 号：P315[天文地球—地震学]