Application Test of Anti-Interference Electrical Method Instrument to Urban Geophysical Prospecting in Tongzhou, Beijing

With the rapid development of the city, it is necessary to obtain geological information within 500 meters. Electrical prospecting is not only low cost and simple operation, but also solves the problem of insufficient drilling density in a survey. However, due to the dense urban buildings and strong electromagnetic interference, it is difficult for traditional electrical instruments to obtain effective data. An anti-interference electrical method instrument is designed. In the application test of Tongzhou core area in Beijing, the resistivity sounding data collected by anti-interference electrical method instrument is stable and reliable;inversion results of sounding are basically consistent with borehole data;the known Zhangjiawan fault and Yaoxinzhuang fault are obvious;basement karst collapse area inferred is basically coincident with the historical collapse area. It is proved that the anti-interference electrical method instrument is effective and can be applied to the geological survey of underground space in other cities.

抗干扰编码电法在通州深部岩溶发育区地质构造探测中的应用

为了查明与通州某建设新区深部岩溶发育有关的地质条件,提供必要的地质基础数据,在研究区开展了抗干扰编码电法勘探。针对研究区强电磁背景干扰,开展了试验分析,优化了采集参数,最终共获得560个测点数据。对原始数据进行精细处理,选取典型剖面进行2D反演,在此基础上,对研究区覆盖层厚度、基岩发育特征及断裂构造走向等进行了综合推断解释,取得了较好的应用效果。部分解释成果与已有钻孔资料吻合,为通州深部岩溶塌陷分析提供了地球物理依据。

北京东部地区深部岩溶塌陷危险性综合评价

关于岩溶塌陷的研究常见于50m以浅,而事实表明,在钻孔施工及岩溶水大量抽取等人为活动的影响下,具有发生深层隐伏岩溶塌陷的风险。结合地质背景,参考岩溶塌陷调查规范,提出深部岩溶塌陷的控制性因素为4大类5种影响因子,分别是碳酸盐岩地层条件(顶板破碎程度)、第四系条件(覆盖层厚度与底部土层性质)、构造条件(断裂构造)、地下水动力条件(水位变幅)。在系统调查分析各因子的基础上,通过基于层次分析的模糊综合评判法,评价了北京东部地区深部岩溶塌陷的危险性,将研究区分为3个等级,提出了地下水位监测、下管固井等工程防控措施。