直线型台阵微动技术在隧道勘察中的应用研究

Research and application of engineering geological microtremor survey technology in tunnel investigation

微动探测技术具有高效、无损、环保、经济效益好等特点,为克服传统微动技术的不足,通过开发软件,不断优化迭代解译算法、外业工作流程等措施,开发出一套新型微动探测系统,提高了微动技术使用范围和解译精度。该技术是基于拓展空间自相关(ESPAC)和H/V谱比法的理论算法,采用直线型台阵滚动重复采集方式,得到相速度、H/V谱比值、峰值频率等核心参数,经过综合分析,能够快捷、直观地获取异常体的地空间分布信息,从而配合地质测绘与钻探查明隧道工程沿线场地工程地质条件,为线路设计与施工提供必要的工程地质资料。这里以某隧道勘察为例,运用直线型台阵微动技术和高密度电法等综合物探方法,结合地质情况对该隧道异常体进行了解释推断,划分了若干异常带和岩性接触带,结论与钻孔、现场地质调绘相符合。理论和实践表明,直线型台阵微动技术在隧道勘察中取得较好的效果,可推广应用。

Microtremor survey technology has the characteristics of high efficiency,non-destructive,environmental protection,and good economic benefits.In order to overcome the shortcomings of traditional microtremor technology,a new engineering geological microtremor survey system has been developed by developing software,continuously optimizing iterative interpretation algorithm,field workflow,and other measures,so as to improve the application range and interpretation accuracy of microtremor technology.This technology is based on the extended spatial autocorrelation(ESPAC)theoretical algorithm and the H/V spectral ratio method.It uses a linear array to obtain core parameters such as phase velocity,H/V spectral ratio,peak frequency,etc.Through comprehensive analysis,it can quickly and intuitively obtain the geospatial distribution information of abnormal bodies,cooperate with geological mapping and drilling to find out the engineering geological conditions of sites along the tunnel project,and provide necessary engineering geological data for line design and construction.Taking a tunnel survey as an example,this paper interprets and infers the abnormal body of the tunnel by using the microtremor survey technology by linear array,high-density electrical method,and other comprehensive geophysical methods,combined with the geological conditions,and divides several abnormal zones and lithologic contact zones.The conclusion is consistent with the drilling and field geological mapping.Theory and practice show that the engineering geological microtremor survey technology has achieved good results in tunnel investigation and can be popularized and applied.