水平泥岩砂岩互层隧道支护体系力学特性试验研究

公路隧道穿越水平泥岩砂岩互层施工过程中支护体系力学特性较为复杂，通过开展大梁峁特长公路隧道水平泥岩砂岩互层段支护体系现场试验，研究水平泥砂岩互层段隧道初期支护中的锚杆轴力、围岩压力，钢架应力、混凝土应力及支护变形，二次衬砌中接触压力和混凝土受力特征。分析表明：拱部锚杆作用明显，边墙锚杆受力较小，建议锚杆由拱部160°减少至拱部120°，同时适当增加拱部锚杆；围岩压力在断面开挖后7d时间内已基本达到最大围岩压力的80％左右，说明在该种岩层中隧道开挖后围岩压力释放较快；水平泥岩砂岩互层关键控制点在拱部位置，边墙部位的支护结构无论从受力还是变形来说均较小；研究成果可为水平层状岩层隧道及类似工程的修建提供参考。

Experimental Study of Mechanical Characteristics of Support System for Tunnel in Horizontally Bedded Sandstone and Mudstone Interbed

The supporting system mechanics characteristic is more complicated for highway tunnel in horizontally bedded sandstone and mudstone interbed,In-situ experiments of support system were carried out to investigate bolt axial force, rock mass pressure, steel framework stress, concrete stress and tunnel deformation of primary support,contact pressure and concrete stress for lining in the Daliangmao Super-long highway tunnel. The results show that the bolts have an obvious effect at arch area, and the bolt axial forces at the sidewall are smaller,the bolt range at arch area were subjected to reduce 120° ,at the same time,increasing the bolts at arch area appropriate;The rock mass pressure release quickly after ex- cavation ,because the rock mass pressure has released 80% in seven days;the key control point is at the arch area for tunnel in horizontally bedded sandstone and mudstone interbed,and the stress and deformation of the support system is smaller at sidewall. The results can be adopted in the design,construction and research of similar tunnels.