在岩溶发育地段施工冲孔灌注桩,对于溶洞高度较大,且溶洞为半填充或无填充型(填充物多为可塑或硬塑粘性土及少量灰岩碎块),溶洞顶板面为饱和粉细砂层,采用钢护筒固孔施工,有效避免由岩溶导致的地表塌陷和粉细砂层流失导致的孔内塌方,对顺利成桩起了关键作用。 For the construction of perforated cast-in-situ piles in the karst development zone, the cave height is relatively large, and the karst cave is semi-filled or unfilled (mostly filled with plastic or hard plastic clay and a small amount of limestone fragments) Fine sand layer, the use of steel casing solid hole construction, effectively avoiding the surface collapse caused by karst and the loss of fine sand layer caused by the hole collapse, played a key role in the smooth pile.