扩大头锚杆结合控制性降水桩锚支护设计研究

Research on Pile-anchor Retaining Structure of Head Enlarged Anchor Combined with Controlled Precipitation

地下水位较高且存在饱水砂层和软土层地质条件下的基坑支护是岩土工程的难题之一,传统的内支撑支护存在造价高、施工工期长的缺点,扩大头锚杆桩锚支护是相对经济合理的支护方式。为解决该支护方式在应用中存在的问题,以滨海复杂地质和环境条件下某污水泵站基坑支护工程为例,对采用扩大头锚杆结合控制性降水技术的桩锚支护设计方法进行了探讨。采用扩大头锚杆技术可以解决饱水砂层中锚杆施工时涌砂冒水的问题,缩短施工工期;采用控制性降水技术可以解决因锚杆道数减少导致的支护桩弯矩过大,配筋过多问题。实践表明,扩大头锚杆结合控制性降水桩锚支护技术取得了良好的支护效果,值得类似工程借鉴。

It is one of the difficult problems of geotechnical engineering to support the foundation pit under the geological conditions with high groundwater level and saturated sand and soft soil layer. However,the traditional interior support has the disadvantages of high cost and long construction period. On the contrary,the head-enlarged-anchor pile support is a relatively economic and reasonable method. In order to solve the problems in the application of this method,the foundation pit support engineering of a sewage pump station case under the complex geological and environmental conditions in the coastal area is illustrated,and the design method of pile-anchor support with the technology of enlarged head anchor and controlled precipitation is discussed. The technology of enlarged head anchor can solve the problem of sand and water gushing during the construction of anchor in the saturated sand layer and shorten the construction period;the technology of controlled precipitation can solve the problem of too large bending moment and too much reinforcement due to the reduction of anchor number. The practice shows that the enlarged-head-anchor pile combined with the technology of controlled dewatering has achieved good supporting effect,which can provide reference to similar projects.