基于电阻率成像技术的基坑渗漏探测方法

摘要

随着城市建设的不断发展和进步,地下工程规模越来越大,各种超大超深基坑不断出现,特别是在软土和地下水丰富、水位较高地区,由于基坑工程的渗漏问题导致的工程事故时有发生.基坑渗漏是基坑止水帷幕施工中常见的一种施工缺陷,所以预先对基坑围护体系的渗漏情况进行探测,若发现有渗漏区域在开挖之前及时进行处理与预防就显得尤为必要.这里阐述基坑围护体系发生渗漏时,基坑周围地下水流线的变化特征,流线向渗漏处聚集,渗流位置的水流线密集区域渗流阻力小,导致基坑周围土体的渗漏处电阻率变低.给出了基于电阻率成像技术,通过探测基坑周围土体在基坑降水前后的电阻率变化,进行基坑渗漏探测的方法,并通过两个工程实例说明该方法能探测出基坑渗漏三维位置,探测结果客观准确.%With the continuous development of city construction and development of underground engineering,increasingly large scale,all kinds of super large and deep foundation pit appear constantly,especially in soft soil and groundwater rich,high water level area,due to the leakage problem of the foundation pit engineering,the accidents happen.Pit leakage is a common construction defect of construction waterproof curtain,therefore,it is necessary to detect the leakage situation of the foundation pit supporting system in advance,if it is found that the leakage area is treated and prevented in time.At present,the problem of foundation pit leakage detection is commonly used in domestic and international water level observation in the foundation pit.It is rare to use the geophysical method to detect the leakage in our country.In this paper,the leakage of foundation pit system,variation of groundwater flow around the foundation pit line,to streamline the leaking water seepage line location aggregation,intensive regional seepage resistance,is resulting in leakage of soil around the foundation pit of low resistivity.Based on the resistivity imaging technique,the method for detecting the leakage of the foundation pit by detecting the change of resistivity of soil around foundation pit before and after dewatering is presented.Two engineering examples show that this method can detect the pit leakage detection results of three-dimensional position,detection results objectively and accurately.