填筑土、砂卵石等不良地层中灌注桩塌孔处理及预防措施

Treatment and Preventive Measures for Collapse of Cast-in-place Piles in Poor Strata of Filled Soil and Gravel in Yibin City

摘要:

以宜宾市区的两个下穿隧道项目工程为实际案例，详细介绍了素混凝土回填复钻工法、长护筒护壁工法和跟进式护筒成桩工法在灌注桩施工过程中处理及预防塌孔方面的应用，得到主要结论有：素混凝土回填复钻工法可用于局部深度、局部平面范围旋挖钻成孔、塌孔问题的处理，有施工周期短、施工占地面积小、综合造价较低的优势；长护筒护壁工法主要用于较大深度填土、软土等地层，施工占地面积大，施工方便，对于工期影响小；跟进式护筒成桩工法的施工速度快，施工场地要求不高，几乎可用于所有土层，施工速度快，施工占地面积小，造价高。以上3种处理措施的应用可为宜宾乃至全国在高厚填土、砂卵石等不良地层中灌注桩塌孔的处理及预防提供重要参考价值。

Abstract:

Taking two underpass tunnel projects in Yibin as the practical cases, the application of plain concrete backfill drilling method, long casing wall protection method and follow-through casing pile construction method in the treatment and prevention of hole collapse during the construction of cast-in-place piles is introduced in detail. The main conclusions are obtained that the plain concrete backfill drilling method can be used to deal with the problems of rotary drilling and hole collapse in local depth and local plane ranges, and has the advantages of short construction period, small construction area and low comprehensive cost. The long casing wall protection method is mainly used for the deep fill, soft soil and other strata, and its construction area is large, the construction is convenient and the impact on the construction period is little. The follow-through casing pile method has the characteristics of fast construction speed and not high construction site requirements, and can be used in almost all soil layers with a fast construction speed, small construction area and high cost. The application of the above three treatment measures can provide the important referring values for treating and preventing the hole collapse of cast-in-place piles in the poor strata of thick filled soil and gravel in Yibin and even the whole country.