云母片岩隧道围岩大变形分析研究

随着铁路建设的快速发展,隧道工程的比重不断加大,云母片岩隧道围岩大变形已严重影响了隧道施工安全和进度,本文为解决这些问题,通过对宝兰高铁杨家庄隧道云母片岩结构特性、矿物成分、抗压强度和水理特性等工程特性的介绍,对云母片岩隧道围岩大变形特征及变形因素进行分析研究。(1)变形特征:沉降收敛变形量大,变形速率快,变形持续时间长,变形差异大,洞身纵向变形分布不均及破坏形式多样性;隧道围岩变形与隧道围岩压力有着密切相关性,且早期变形严重,半个月后逐渐趋于稳定。(2)变形因素:地形地貌、岩性特征、岩体结构、地下水及围岩压力是云母片岩隧道围岩大变形的主要因素;单斜地层和地形产生偏压、开挖卸荷后围岩受地下水渗流软化沿变质片理面及泥质夹层产生塑性蠕变,使围岩压力分布不均等因素是导致杨家庄隧道围岩大变形的根本原因。

Analysis and Research on Large Deformation of Surrounding Rock of Mica-schist Tunnel

With the rapid development of railway construction,the proportion of tunnel engineering has been increasing.The large deformation of mica-schist tunnel surrounding rock has seriously affected the safety and progress of tunnel construction.In order to solve these problems,this paper analyzed and studied the large deformation characteristics and deformation factors of mica-schist tunnel surrounding rock by introducing the structural characteristics,mineral composition,compressive strength and hydraulic characteristics of mica-schist in Yangjiazhuang Tunnel of Baoji-Lanzhou High-speed Railway.The research shows as follows:(1) for deformation characteristics,the settlement convergence deformation amount is large,the deformation rate is fast,the deformation duration is long,the deformation difference is large,the distribution of longitudinal deformation of tunnel body is uneven and the failure forms are diverse;tunnel surrounding rock deformation is closely related to tunnel surrounding rock pressure,and the early deformation is severe,and gradually tends to be stable after half a month.(2) For deformation factors,topography,lithologic characteristics,rock mass structure,groundwater and surrounding rock pressure are the main factors of large deformation of mica-schist tunnel surrounding rock;biased strata and terrain create bias,plastic creep of surrounding rock along metamorphic schistosity surface and argillaceous interlayer due to softening of groundwater seepage after excavation and unloading,and uneven distribution of surrounding rock pressure are the fundamental causes of large deformation of surrounding rock in Yangjiazhuang Tunnel.