Method for forming pile foundation in karst area: Fid-Bau Portal

Method for forming pile foundation in karst area

LIU ZHIHANG / ZHAO JIANHAI

The invention provides a pile forming method for a pile foundation in a karst area. The method comprises the steps that the positions and the number of karst caves are comprehensively determined according to advanced drilling, pipe wave detection and the drilling process of a rotary drilling machine; in the drilling process of the rotary drilling machine, a special drill bit is used at the position of the karst cave to press pile core soil and gravel into the karst cave, and the compactness of filler in the karst cave is increased; a thickened double-layer reinforced composite membrane is installed outside a reinforcement cage according to data of the specific position of a karst cave, then the reinforcement cage is hoisted into a pile hole, a composite bag is filled with concrete before grouting so that the concrete can block the karst cave, and grouting is conducted after the concrete in the composite membrane reaches certain strength to form a pile foundation. The construction difficulty of a pile foundation in a karst area can be reduced, the defect that semi-filling and non-filling type karst caves are prone to hole collapse is overcome, the later-period karst cave processing procedure is reduced, the problem of slurry leakage in the pile body grouting process is solved, and the composite membrane is low in manufacturing cost and convenient to use.

本发明提供了一种岩溶地区桩基成桩方法。所述方法包括：根据超前钻、管波探测以及旋挖机钻进过程综合确定溶洞的位置与数量；旋挖机钻进过程中，在溶洞位置换用特制钻头将桩芯土与碎石压入洞中，增加溶洞内充填物的密实度；依据溶洞具体位置的资料在钢筋笼外部安装加厚的双层加筋复合膜，然后将钢筋笼吊装至桩孔中，在注浆前先往复合袋中充填混凝土，使其能够堵住溶洞，待复合膜中的混凝土达到一定强度后再进行注浆，形成桩基。本发明可以降低岩溶地区桩基施工难度，解决了半充填与无充填型溶洞较易塌孔的缺点，减少了后期处理溶洞的工序，解决了桩体注浆过程中漏浆的问题，且该复合膜造价低廉，方便使用。

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