管幕预筑浅埋隧道稳定性分析

Analysis of stability of shallow-buried tunnel built by pipe-roof pre-construction method

沈阳某地铁车站是国内首次应用管幕预筑法施工的特大浅埋暗挖隧道,通过对该隧道土方大开挖阶段的稳定性进行分析,提出预支护荷载作用下隧道稳定性分析方法,推导预支护荷载作用下稳定性安全系数计算公式,并依据其工艺特点进行监测设计和分析。研究研究表明：实测地表沉降满足施工要求,且实测衬砌结构的环向应力为-11~15 MPa,为衬砌设计强度35 MPa的31.4%~42.9%;预筑较常规设计方法小的衬砌厚度即可维持隧道的稳定性;基于预支护荷载的隧道稳定性分析方法和安全系数公式对管幕预筑隧道的稳定性分析具有理论和实际意义。

One subway station of Shenyang is the first super-large cross-section tunnel engineering built successfully by pipe-roof pre-construction method（PPM） at home.The stability of tunnel was analyzed during the process of large excavation.The method of analyzing tunnel stability by pre-load was advanced,and the formula of the safety coefficient for tunnel construction by PPM was deduced.Monitoring design and analysis were done according to the feature of PPM.The results show that the ground settlement observation can meet the construction requirements,and the circumferential stress of the lining structure is between -11 MPa and 15 MPa,which is between 31.4% and 42.9% of the designed strength,which means that the smaller thickness of pre-construction lining structure will keep tunnel stable better than conventional design method.It is important to analyse the stability of tunnel built by PPM both in theory and practice based on the formula of the safety coefficient of pre-loaded tunnel stability.