全回转全套管设备在特殊环境复杂地层钻孔灌注桩中的应用

Application of Full Rotary and Casing Equipment in Bored Pile with Complicated Environment and Complex Formation

桩基工程施工时,当遇到紧贴周边地下建筑物对位移敏感的特殊施工环境,或者遇到坚硬深厚卵石层、砾石层,桩位下方存在高承压水,或设计桩位下方存在废桩、浆砌块石、垃圾土等障碍物时,会对桩基施工的顺利成孔、进度与质量造成较大影响。针对上述问题,常规采用泥浆护壁回转成孔、旋挖成孔、冲击成孔的施工方法受到限制,同时存在护壁泥浆污染环境、成孔质量差及垂直度不易控制等缺点,尤其是成孔产生的振动对敏感建筑物造成的影响不容忽视(如地铁周边)。近年来出现的全回转全套管配合旋挖钻机钻进或配合履带吊冲抓钻进技术可以有效进行地下清障或成桩施工,尤其套管超前工况下更适用于地铁周边或周边环境及地质条件和复杂的场合,近年来已被工程界采用。作者从事全回转全套管工程实践,撰写本文共同学习交流,不断提高全回转全套管的施工水平,更大范围得到推广应用。

During the construction of pile foundation,when encountering the special construction environment that is sensitive to the displacement of the surrounding underground buildings,or encountering hard and thick pebble layer and gravel layer,there is high pressure water under the pile or there are waste piles,masonry stone,garbage soil and other obstacles in the design of pile,it has a greater impact on smoothly hole forming,the progress and quality of construction of the pile.In view of the above problems,the conventional method is limited,meanwhile,there are disadvantages such as pollution of wall mud,poor hole forming quality and difficult vertical control,especially the impact of vibrations on sensitive buildings can not be ignored(eg,around the metro).In recent years,the full-turn full pipe with rotary drilling rig drilling or with crawler crane grasping drilling technology can effectively carry out underground clearance or pile forming construction,especially under the casing conditions,it is more applicable to the surrounding subway environment and geological conditions,and in recent years it has been adopted by the engineering community.The author introduces full-turn full-pipe engineering practice to continuously improve the construction of full-turn full-tube construction level and promote a wider range of applications.