非开挖顶管施工技术在病险水库加固工程中的应用

Application of non-excavation pipe jacking construction technology to strengthening of defective and dangerous reservoir

受麦子河水库枢纽工程区为平缓开阔的湖积堆积地形地貌条件的限制,新建输水涵洞只能修建在穿过主坝坝基之下、地下水位较高的第四系湖积层(QL)饱和砂土地层中,施工过程易产生渗水、塌方并影响主坝安全,因此设计、施工中采用非开挖顶管施工技术成洞。顶管段进、出口部位用深层搅拌法进行土体加固,且对管身段进行回填灌浆和固结灌浆。顶管施工段两端工作井、接受井采用沉井施工法,而进口闸井段外壁周边则采用深搅桩板墙初期支护型式。这样,克服了建筑物结构布置的困难,排除了顶管存在渗漏通道安全隐患,解决了基坑开挖渗水、垮塌以及沉降变形问题,达到缩短工期、有效降低工程投资的目的。

Under the limitation from the gently and broaden lacustrine accumulation landform of Maizihe Reservoir,the new water conveyance culvert can only be constructed through the saturated sand strata of the lake sediments of quaternary system（ QL）under the main dam foundation with higher groundwater level,while water seepage and land collapse are prone to occur during the construction and then impact the safety of the main dam. Therefore,the non-excavation pipe jacking construction technology is applied to the tunneling during the design and construction. The deep mixing method is adopted for soil reinforcement at both the inlet and outlet of the pipe jacking section,while backfill grouting and consolidation are made for the jacking pipe-body section. Furthermore,the working shaft and the receiving shaft on both the sides of the jacking pipe construction section are constructed by the open-caisson method. Moreover,the early-stage supporting mode with the deep mixing piles is used around the outer-wall of the inlet gate-shaft. In this way,the difficulties from the layout of the structures are overcome,in which not only the potential safety hazard from the existence of seepage passage along the jacking pipe is eliminated,but the problems of excavation seepage,collapse and subside are also solved,thus the target of shortening the construction period and lowering the project investment effectively is got at last.