The invention discloses a construction method of open caisson in soft soil layer. By setting cement mixing pile at the bottom of the edge foot of open caisson in advance and drilling grouting around the open caisson before sinking, it ensures that the open caisson can uniformly and controllably self-sink when the open caisson sinks by drainage method, after being excavated out of the earth, thereby avoiding the problems of over-sinking and sudden sinking in the sinking process of open caisson. When sinking to the top of cement mixing pile, the mixing pile is broken layer by layer through uniform interval, and large sand bags are set synchronously and evenly. The sand bags filled with sand, i.e. sand boxes, are used to unload and self-sink. The safe and uniform controlled sinking of the caisson is realized, and the large sinking and inclination of the caisson are prevented. The construction method of Caisson in soft soil layer is convenient and reliable in construction technology, convenient in material acquisition, safe and reliable in construction process. The problem of safety and quality risk caused by caisson construction in soft soil layer is solved pertinently, which ensures the construction quality and safety of caisson, effectively reduces the construction cost and meets the requirements of national energy saving and environmental protection.
【技术实现步骤摘要】
软土层沉井施工方法
本专利技术涉及一种软土层沉井施工方法。
技术介绍
沉井结构物是在修建沉井的地面和地坑上,先制作开口钢筋混凝土井筒,做到全高或部分高度(分节时),达到一定强度后,用人工或机械在井筒内不断分层挖土、运土,随着井内土面逐渐降低,沉井筒身借其自重(或外加荷载作用下)克服与土壁之间摩擦力及刃脚下土的阻力,不断切土下沉。采取分节制作时,则在井筒下沉过程中或下沉各个阶段中,逐节加高井筒,继续挖土下沉,如此循环往复,待井筒刃脚达到设计标高后,进行基底整形,浇筑混凝土垫层和钢筋混凝土底板封底。若在软土地层进行大直径沉井施工,因沉井周边的软土层具有天然含水量高、孔隙比大、透水性差、压缩性高、强度低等特点,沉井在下沉施工过程中沉井底部地基承载力不足以承载上部沉井的自重而导致沉井超沉及倾斜等安全质量问题。
技术实现思路
针对在软土层进行大直径沉井施工可能出现的质量问题,本专利技术提出了一种软土层沉井施工方法,目的是使大直径沉井在软土地层下沉时避免发生沉井倾斜及超沉等质量问题,使沉井平稳的沉至设计标高位置。具体采用如下技术方案:本专利技术提供的软土层沉井施工方法通过预先在沉井刃脚底部设置水泥搅拌桩并在沉井下沉之前在沉井外周钻孔注浆,确保沉井在采用排水法下沉的过程中沉井随着土方被挖运出去后能均匀可控的自沉,从而避免沉井在下沉过程中发生超沉及突沉的问题,当沉井下沉至水泥搅拌桩(实桩部分)桩顶时,通过均匀间隔逐层破除搅拌桩,并同步均匀设置大砂袋,利用装满砂的砂袋即沙箱作用进行卸荷自沉,实现沉井安全、均匀受控下沉,防止沉井大幅下沉及倾斜。通过上述对三个关键技术措施的组合利用 ...
【技术保护点】
1.一种软土层沉井施工方法,其特征在于:通过预先在沉井刃脚底部均匀地设置一定数量的水泥搅拌桩,增大沉井刃脚端部复合地基承载力,防止沉井在沉井超沉;在沉井下沉之前,在沉井外壁周围钻孔注浆改良井周土体力学性能,增加外壁摩擦力,与底部搅拌桩共同作用防止大幅度下沉;沉井下沉至搅拌桩桩顶时,通过均匀间隔逐层破除搅拌桩,并同步均匀设置砂袋,利用砂袋的沙箱作用进行卸荷自沉,实现沉井安全、均匀受控下沉。
【技术特征摘要】
1.一种软土层沉井施工方法,其特征在于:通过预先在沉井刃脚底部均匀地设置一定数量的水泥搅拌桩,增大沉井刃脚端部复合地基承载力,防止沉井在沉井超沉;在沉井下沉之前,在沉井外壁周围钻孔注浆改良井周土体力学性能,增加外壁摩擦力,与底部搅拌桩共同作用防止大幅度下沉;沉井下沉至搅...
【专利技术属性】
技术研发人员:何亮,张文浩,何德华,邱永钦,陈建宁,董志杰,林涛,杨添,王少萍,招日兴,欧文熹,沈伟滨,
申请(专利权)人:广州市第三市政工程有限公司,广州市市政集团有限公司,
类型:发明
国别省市:广东,44
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