岩溶地区冲孔桩施工技术措施探讨

岩溶地区由于地质条件复杂,建筑物桩基选型应慎重。根据工程经验,冲孔桩较适宜,但冲孔桩的施工仍存在一定的技术难点。某新机场航站楼地处石灰岩地区。第四系覆盖层中砂层厚度大,下伏基岩岩溶发育强烈、岩面起伏、倾角陡、裂隙发育、土洞及溶洞广泛分布,地下水埋深浅、地质条件相当复杂;冲孔桩施工时不可预见因素多,特别是成孔时事故多,全岩面难以正确判断、水下灌注混凝土困难等。在认真分析了施工过程中可能存在的技术难点后,不断摸索总结经验,有针对性的采取了各种合理有效的技术措施。

DICUSSION OF THE CONSTRUCTION TECHNICAL MEASURE FOR THE PERCUSSION BORING INJECTION PILE IN KARST REGION

The pile foundation type should be chosen carefully as the geological conditions are very complicated in the Karst region. The percussion boring injection pile is rational type, however, much difficulties will be faced during construction. In this paper, a successful case of the construction of percussion boring injection pile for a certain new airport building in Karst region is stated. In the construction site, the complicated geological conditions, such as the thick sand layer, the undulate surface of the stiff limestone, the high dip angle, the developed crake and Karst cavern, made much trouble during the construction. Especially, much attention should be paid to the prevention from accidents during percussive drilling, the criterion of the rock full-face, the injection of underwater concrete and the other unpredicted trouble. After the difficulties are analyzed carefully, the effective and rational technical measure is adopted.