龙泉市鼎丰壹城大直径钻孔桩施工难点与对策

龙泉市鼎丰壹城桩基项目主要有桩径大、单桩极限承载力大等特点,最大桩径达2400 mm，单桩竖向极限承载力达89600 kN，建筑领域参考经验较少。本桩基工程主要面临砂层和卵石层易塌孔、入岩难和沉渣清理困难等三大挑战。结合国内桥梁、铁路桩基施工经验，通过增加砂层和卵石层稳定性、采用分级扩孔和孔底除渣等关键技术，针对性解决现场施工难题。灌注桩达到龄期后，经现场检测，施工完成的桩大多为I类桩。通过对本工程施工经验的总结，为大直径旋挖钻孔灌注桩在建筑领域的应用提供借鉴。

Construction difficulties in large diameter bored piles at Dingfeng Yicheng in Longquan City and the solutions to them

The Longquan Dingfeng Yicheng pile foundation project was featured of large pile diameter and high ultimate bearing capacity of the single pile where the maximum pile diameter was 2400mm, and the vertical ultimate bearing capacity of the single pile was 89600kN. There is little reference experience in the construction field. The pile foundation project mainly faced three challenges: easy caving in the sand layer and pebble layer, difficulty in bedrock penetration, and difficulty in clearing sediment. In reference to the pile foundation construction experience of bridges and railways in China, the key technologies such as stabilization of the sand layer and pebble layer, step reaming, bailing out hole bottom sediments, were purposely targeted to solve the construction problems. Testing after the waiting period showed that most of the bored piles were Class I piles. The summary of the construction experience of this project can provide reference for the application of large diameter rotary bored piles in the construction field.