基于反射波法的钻孔灌注桩桩底溶洞声纳探测方法及应用.doc

钻孔灌注桩桩底溶洞声呐探测方法及应用研究 石振明1,2，刘鎏1,2，彭 铭1,2，陶凤娟1,2，刘春生3. 同济大学地下建筑与工程系 上海 200092；2.同济大学岩土及地下工程教育部重点实验室 上海 200092；3.武汉长盛工程检测技术开发有限公司 湖北 武汉430312） 摘要 (1.Department of Geotechnical Engineering，Tongji University，Shanghai 200092；2.Ministry of Education Key Laboratory of Geotechnical and Underground Engineering，Tongji University，shanghai 200092；3. Wuhan Conourish Engineering Exploration Technology Development Co.，Ltd.，Wuhan，Hubei 430312) Abstract：Bored piles technology is commonly adopted to carry out large-scale construction projects in the area with karst. However, those karst cavities under pile bottom may lead to hole collapsing, drill burying, mud leakage, and some other accidents. These potential risks have significant impact on both project itself and surrounding buildings. Due to the necessary mud protection in bored pile construction, many geophysical methods at current stage are not applicable for the karst cavities detection. This research introduces a sonar technology for the detection of karst cavities located under bored pile combining features of sonar stress wave propagation. A sonar detector (JL-SONAR) and a signal analysis software (PBCA) are developed for this purpose. JL-SONAR detector is responsible for the transmission and collection of sonar signals, and PBCA software is designed to analyze and sort the detection data. This technology makes full use of drilling mud, and enables a 10 meters detection range for the condition detection of the karst cavities under pile bottom during drilling. The technology has been applied to two projects for feasibility study. The sonar detection technology has some advantages such as low cost, high speed, and high precision. The technology introduced in this paper provides a new solution to karst cavities detection, especially in liquid environment. Keywords：karst; karst cavities detection; sonar; reflected wave method; bored pile 1 引 言 我国是世界上岩溶发育最广泛的国家之一，总面积达346万km2，占国土面积1/3。以桂、黔和滇东部地区分布最广，湘西、鄂西、川东、鲁、晋等地也有较广的分布[