瞬态瑞雷面波勘探中隐伏溶洞的响应特征研究

Response characteristics of covered karst cave in transient rayleigh surface wave exploration

瞬态瑞雷面波法勘探中,掌握隐伏溶洞的响应特征是进行野外探查分析的基础。结合两类填充状态隐伏溶洞,使用有限差分法进行数值模拟,分别构建不同发育介质溶洞模型。并利用贵广铁路隐伏溶洞探测实例验证探测效果。分析认为:瑞雷面波法对面波相速度差异反映敏感,精度较高,对基岩面和两种类型隐伏溶洞分辨率高;对于填充溶洞,速度响应由溶洞中充填介质的物性决定,一般为低速反映;对于空溶洞,速度较粘土层及基岩均为低速反映;两种溶洞探测面波频散曲线在溶洞位置都会出现较为形象明显的“之”字形拐曲。取得的结果可为工程应用提供借鉴。

In transient Rayleigh surface wave exploration,it is the basis of field exploration and analysis to grasp the response characteristics of hidden caves.Combined with two types of filling caves,the finite difference method was used to simulate the caves,and the cave models of different developing media were constructed respectively.The detection effect is verified by an example of hidden karst cave detection on Guizhou-Guangzhou railway.It is concluded that Rayleigh surface wave method is sensitive to the difference of surface wave phase velocity,with high accuracy and high resolution to bedrock surface and two types of hidden karst caves;for filling karst caves,the velocity response is determined by the physical properties of filling media in Karst caves,which is generally low-speed reflection;for empty karst caves,the velocity is lower than that of clay layer and bedrock;and for two types of karst caves,the wave dispersion curves of detection surface are low-speed reflection.The position will appear obvious"Zigzag"inflection,and the results can be used for reference in engineering application.