某封闭煤场改造项目钻孔灌注桩与劲性复合桩方案对比分析

Comparative Analysis of Bored Cast-in-situ Piles and Rigid Composite Piles in a Closed Coal Yard Reconstruction Project

全封闭储煤场储煤棚20年来运行安全可靠,得到业主及环保部门一致认可,一般可设计成条形或者圆形封闭结构,结构跨度大,高度高,限于上部结构对水平荷载的要求较高,封闭煤场项目基础形式大部分采用桩基础。桩基础一般选择可靠性较高的钻孔灌注桩,但在湿陷性场地灌注桩设计需要考虑负摩阻力,桩长往往很长,当采用泥浆护壁施工时沉渣不宜控制,工期长,造价高。而劲性复合桩突破了单一桩型的局限性,可以根据场地地质条件选择两种或两种以上的桩型复合为同一桩体,形成互补增强的复合桩。本工程拟采用MC长芯劲性复合桩,外芯采用高压旋喷水泥土桩(湿法搅拌工艺),内芯采用锤击或静压打入高强预应力管桩,并在复合桩四周搭接四根水泥土桩用以消除场地湿陷性,是一种技术可行、经济合理的方案。

The coal storage shed of the fully enclosed coal storage yard has been operating safely and reliably for 20 years,and has been unanimously approved by the owners and environmental protection departments.It can generally be designed as a strip or circular closed structure with a large structure span and high height,which is limited to the requirements of the upper structure for horizontal load.Most of the foundation forms of high and closed coal yard projects use pile foundations.Generally,the pile foundation is a bored cast-in-place pile with high reliability.However,the design of the cast-in-place pile in a collapsible site requires consideration of negative friction resistance,and the pile length is often very long.When the mud wall is used for construction,the sediment should not be controlled.The strength composite pile breaks through the limitation of a single pile type,and two or more pile types can be selected as the same pile body according to the site geological conditions to form a complementary reinforced composite pile.This project intends to use MC long-core stiff composite piles,the outer core of which is a high-pressure spin-cementsoil pile(wetmixing process),the inner core of which is driven into the high-strength prestressed pipe pile by hammering or static pressure,and placed around the composite pile.It is a technically feasible and economically reasonable solution to connect four cement soil piles to eliminate the site's collapsibility.