重载铁路隧道穿越富水砂层综合施工技术研究

重载铁路隧道长段落穿越第三系富水砂层,隧道开挖后,在地下水渗流作用下,富水砂层颗粒随水流失、粉质黏土含水率增大,诱发掌子面砂层、粉质黏土等变形失稳,局部甚至发生涌砂、突泥、突水现象,严重影响施工进度。为此,根据地层性质及成因分析,采用理论与现场试验相结合的动态设计,确保施工安全。设计中采用了对围岩超前预注浆加固封堵地下水、掌子面玻纤锚杆注浆提高核心土的整体稳定性,拱部超前大管棚预支护控制围岩变形,长导管泄水降压降低周边砂层的含水量,施工过程"快挖、快支、快封闭"的原则,从而实现安全开挖,快速通过的处理方案,可为类似工程提供借鉴。

Study on Comprehensive Construction Technology for Heavy Haul Railway Tunnel Passing Water-rich Sand Layer

Where a heavy haul railway tunnel long passes through tertiary water rich sand stratum,the loss of sand particles on account of water flow,the increase of water content in silty clay,the deformation and loss of stability of face sand layer and silty clay,the local sand gushing,mud bursting and water inrush are encountered because of underwater seepage due to tunnel excavation,which seriously affect the construction progress. Based on formation characteristics and cause analysis,dynamic design by means of theory and field test is conducted to ensure the safety of construction. Advanced grouting in surrounding rock is used to block groundwater and tunnel face fiberglass bolt grouting is employed to improve the overall stability of the tunnel face core soil. Arch leading large pipe roof reinforcement is designed to control the deformation of surrounding rock and long catheter drainage pressure is proposed to reduce surrounding sand moisture content. Quick excavation,quick supporting and quick closing are performed to achieve safe excavation and rapid passing. All these measures may provide references for similar projects.