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沿海许多剥蚀残丘地貌地区,典型地质特点是上部覆盖较浅的流塑淤泥层,下卧全风化、中风化花岗岩,岩面起伏较大。针对该类地质条件下地下结构埋入基岩的深基坑,采用锚杆(索)等支护方式比较困难或成本较高,本文介绍了利用吊脚嵌岩灌注桩+内支撑方式对基坑进行支护,提出了支护桩嵌岩深度和围岩厚度的计算方法,采用提前钻孔装药方式对坑内基岩进行静力破碎开挖技术。经工程实践证明,该理论和方法既确保基坑安全,又降低基坑支护及开挖的综合成本。
Many coastal denuded remnant mound area, the typical geological characteristics of the upper part of the shallow cover of the plastic sludge layer, under the full weathered, weathered granite, rock surface larger ups and downs. For the deep foundation pit with underground structure embedded in bedrock under such geological conditions, it is more difficult or costly to adopt the anchor (cable) support method. This paper introduces the use of anchor foot embedded rock piles + internal support The method of calculating the depth of embedded rock and the thickness of surrounding rock is put forward, and the technology of static crushing and excavation of the bedrock inside the pit is advanced by the way of pre-drilling charge. The engineering practice has proved that the theory and method not only ensure the safety of foundation pit, but also reduce the comprehensive cost of foundation pit support and excavation.