高强钢筋格栅在Ⅳ级围岩隧道中的支护效果研究

Study on support effect of high-strength steel grille in tunnel with Ⅳ grade surrounding rock

热处理高强钢筋具有高强度、延性好、强屈比高、应变时效敏感性低、焊接和冷弯性能好等诸多优点,然而格栅拱架所用钢筋能否利用高强钢筋进行替代在国内尚未进行研究。文中依托成兰铁路柿子园隧道Ⅳ级围岩区间工程,分析了高强格栅支护抗弯刚度,并用18mm高强钢筋格栅拱架代替22mm普通格栅与工16型钢钢架,进行现场对比试验,对三种钢架的围岩压力,钢架应力与围岩变形进行监测,对比分析高强钢筋格栅在Ⅳ级围岩隧道中应用效果。研究表明:(1)三种钢架中,高强格栅抗弯刚度最小,支护呈现出一定柔性特点;(2)高强格栅能够最早地控制围岩压力,钢架应力,围岩收敛发展,支护性能最好;(3)高强格栅强度高,能够提供最高的支护安全储备。18mm高强格栅在Ⅳ级围岩隧道显示出很好的支护效果。

The heat treated high strength steel bars have many advantages,such as high strength,good ductility,high strength ratio,low strain ageing sensitivity,good welding and cold bending performance,etc. However,whether the steel bars used in the grid arch can be replaced by high strength steel bars have not been studied in our country. In this paper,the flexural rigidity of high-strength grille support is analyzed,and the field test is carried out by using the 18 mm high-strength steel grille arch instead of the 22 mm ordinary grille and the I16 steel frame. The follow items were compared,including pressure between surrounding rock and primary lining,internal force of the steel arch and displacement of tunnel inner perimeter. The support effect of high-strength steel grille in tunnel with Ⅳ grade surrounding rock is discussed. The results show that:( 1) the stiffness of the high strength grille is the smallest,and the support shows some flexibility characteristics.( 2) High-strength grille can be the earliest control of the surrounding rock pressure,steel frame stress,the convergence of the development of the surrounding rock,showing the best support effect.( 3) High strength grating high strength,can provide the highest support safety reserves. 18 mm high-strength grille in tunnel through the Ⅳ-grade surrounding rock shows a good support effect.