A sonar detection technology for karst cavities under bored piles and its application
SHI Zhenming1,2,LIU Liu1,2,PENG Ming1,2,TAO Fengjuan1,2,LIU Chunsheng3
(1.Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;3. Wuhan Conourish Engineering Exploration Technology Development Co.,Ltd.,Wuhan,Hubei 430312,China)
Abstract:Those karst cavities beneath the bottom of cast piles in bore hole have significant impact on the project itself and the surrounding buildings. Due to the necessary mud protection in bored pile construction,many geophysical methods at current stage are not applicable for the karst cavity detection. A sonar technology for the detection of karst cavities located beneath the bored pile was proposed utilizing the features of sonar stress wave propagation. A sonar detector(JL-SONAR) and a signal analysis software PBCA were developed. JL-SONAR detector was responsible for the transmission and collection of sonar signals,and PBCA software was designed to analyze and sort the detection data. The technology makes full use of drilling mud,and enables the detection of the karst cavities within the range of 10 meters below the pile bottom during drilling. The technology was applied in two projects successfully and has the advantages of low cost,high speed and high precision.
周翰斌. 岩溶地质覆盖层及溶洞预处理嵌岩钻孔桩施工技术[C]//第二届全国地下、水下工程技术交流会论文集. 宁波:施工技术杂志社,2011:198-202.(ZHOU Hanbin. Built-in-rock bored pile construction technology of pre-treatment to cover layer and karst cave in karst geology[C]// Proceedings of The Second National Conference of Underground,Underwater Engineering Technology. Ningbo:Construction Technology Magazine,2011:198-202.(in Chinese))
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