下穿铁路站场超浅埋小净距城市隧道设计

摘要

As a new channel connecting Qinglongchang area to the central area of Chengdu, Zhili road tunnel crosses underneath operating 14 track of the railway yard, which is characterized by paral el tunnels with smal clearance, super shal ow-bury, large span excavation.Through the investigation and theoretical analysis, such as double initial support,φ299 super-long pipe curtain with auger bit dril ing and pipe jacking and longitudinal butt joint method, reinforcing the foundation of pipe with piecewise level jet grouting, strengthening the shared rock between tunnels, microstep method with core soil reserved for surrounding rock, strengthening tunnel face by grouting glass fiber bolts, are taken. analysising on the double adjacent construction condition of tunneling under the existing railway and tunnels with smal clearance by numerical simulation, ascertains influence scope of the settlement trough and the reasonable longitudinal construction pace of 2 tunnels, near-construction countermeasures such as crane rail vertical and horizontal beam reinforcement method, monitoring measurement,are formulated, in order to not only ensure the safety running of the railway, provides the reference for the design and construction of similar projects and further studies.%成都市新建致力路工程作为连通青龙场片区至中心城区的通道，以2座小净距超浅埋大跨度暗挖隧道下穿运营铁路站场及动车所14股道。通过调查研究和理论分析，拟定隧道采用双层初期支护、拱部一次性打设φ299超长管幕（螺旋导向顶管钻+纵向错口对接工法）、分段水平旋喷加固管幕基础、双洞净岩柱加固，微台阶留核心土法施工，掌子面玻璃纤维锚杆加固的方案；结合数值模拟，对下穿既有铁路、小净距隧道双重近接施工工况进行分析，确定沉降槽影响范围和双洞合理纵向施工间距，制定了既有线吊轨纵横梁加固法、监控量测等近接施工对策，以保证既有铁路安全运行，为类似工程的设计、施工和进一步研究提供参考。