CRD+顶撑控制技术在密贴下穿工程中的应用

Application of CRD + Top-bracing Control Technology in Close-attached Under-crossing Engineering

研究目的:随着轨道交通建设的大力发展,新建线路穿越既有线路的工程实例越来越多,然而传统的下穿施工工艺难以控制既有结构沉降量且造价较高,本文结合北京地铁新建10号线公主坟站密贴下穿既有1号线公主坟站工程实例,研究一种能够有效控制既有结构沉降量且造价适中的下穿施工工艺,为以后类似工程提供方案支持。研究结论:(1)掌子面应力释放、开挖时基底的扰动、开挖高度大、初支结构封闭时间长以及千斤顶不能及时加顶均会影响既有站底板结构沉降量,其中掌子面应力释放是引起既有站沉降的主要原因;(2)施工过程中通过增加临时立柱和千斤顶、型钢钢架基底处理、超细水泥浆初支背后回填注浆、多台千斤顶同时加力顶升等措施可以控制既有结构沉降量,其中千斤顶加力顶升可以是有效地控制最主要贡献力量。(3)CRD+顶撑控制技术可以有效的控制既有1号线车站沉降量,使其满足3 mm沉降指标。

Research purposes： With the powerful development of the urban rail transit, three are more and more new tracks to cross the existing track engineering. However, it is difficult for the traditional construction technology to control the settlement of the existing structures and it needs higher cost. In this paper, combined with the construction of the Gongzhufen Station of the Line 10 of Beijing metro to under - cross the Gongzhufen Station of the Line 1, the introduction is given to the construction technology that is available for effective control of the settlement of the existing structure with the appropriate cost to provide the reference to the similar works. Research conclusions： （ 1 ） The settlement of the bottom plate structure of the existing station is affected by the release of stress of the working face, the disturbance to bottom during excavation, the excavation height, the long closure time of the primary support structure and no timely jacking of the jack, and the release of the stress of the working face is the main reason for the settlement of the existing structure. （2） The settlement of the existing structure can be effectively controlled by taking the measures of adding the temporary columns and jacks, reinforcing the foundation base with steel frame, grouting to the back of the primary support with extreme fine cement paste and jacking up by jacks, and thejacking up by the jacks is the most powerful means to control the settlement. （3） The CRD ＋ top brace control technology is available for effective control of the settlement of the existing station and meet the settlement of 3 mm.