破碎千枚岩隧道施工期位移安全控制基准研究

Safety control criteria of displacement during construction of broken phyllite tunnels

随着以千枚岩为主的软岩隧道的大量兴建,建立针对性的位移安全控制基准已成为工程界亟待解决的难题之一。以横跨5.12震区的广（元）甘（肃）高速公路杜家山隧道为工程背景,采用室内模型试验及现场试验相结合的研究手段,通过对以V级围岩为主的破碎千枚岩隧道在不同埋深、施工工法及支护参数等条件下位移变形规律的研究,揭示埋深、施工工法、支护与隧道位移间的关联性,结果表明较之工法、支护参数而言,埋深对隧道变形的影响更为显著。并以拱顶沉降作为主要控制指标,以衬砌裂损的出现作为隧道稳定性的判别标志,结合依托工程现场统计数据的系统分析,建立破碎千枚岩隧道中埋深在300 m以内、三台阶法（核心土）以及F3~F5支护方式下的施工期位移安全控制基准。

Many tunnels have been constructed in phyllite rock and the displacement criteria in safety control for phyllite tunnels has become an urgent problem to be solved. The Dujiashan tunnel of Guang（Yuan）—Gan（Su） expressway passing through the Wenchuan earthquake zone was studied. The deformation under different buried depths,construction methods and supporting parameters in broken phyllite of grade V was studied with indoor model tests and field tests. The results indicated that the depth influenced the tunnel deformation more than the construction methods and the supporting pattern did. The vault settlement was considered as the main control indicator,and the line cracking was considered as the symbol of stability of the broken phyllite tunnel. The field dada was analyzed statistically. A displacement criteria of safety control during the construction under the conditions of the buried depth〈300 m,three benches（reserved core soil） and supporting pattern of F3–F5 in broken phyllite tunnel was established.