高强钢筋格栅在Ⅴ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 Ⅴ-grade surrounding rock

与普通钢筋相比,热处理高强钢筋具有强度高、延性好、强屈比高等力学性能优势,然而在铁路软岩隧道中能否用高强钢筋格栅来代替型钢拱架尚需要进一步研究。该文依托成兰铁路柿子园隧道,选取条件基本相同的60m典型Ⅴ级围岩段为试验段,对高强钢筋格栅和型钢钢架支护时的围岩与初支接触压力、拱架应力及洞周位移进行实测对比分析,分析了高强钢筋格栅在软岩隧道中的支护效果。研究表明:(1)φ22mm高强钢筋格栅支护抗弯刚度较小,呈现出柔性支护特点;(2)高强钢筋格栅与混凝土结合性能好,二者协同工作效果好,能够更好的控制支护内力,围岩压力与隧道变形;(3)高强钢筋格栅强度等级高,能提供更高的支护强度安全储备。高强钢筋格栅在软岩隧道中展现出很好的适用性。

Compared with ordinary steel,the heat-treated high-strength steel has the advantages of high strength,good ductility and high flexor ratio. However,it is necessary to further study whether high-strength steel grille can replace steel arch in soft rock tunnel. Based on the construction of the Shiziyuan tunnel in Chengdu—Lanzhou railway,60 m long tunnel in typical Ⅴ-grade surrounding rock was chosen as the experimental section. The follow items were compared when there exists high-strength steel grille arch or steel arch,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 soft rock tunnel is discussed. The results show that:( 1) the bending stiffness of 22 mm high strength steel grille supporting is lesser,presents the characteristics of flexible supporting.( 2) High-strength steel grille can be better combined with concrete,the two work together well,to better control the internal forces of support,surrounding rock pressure and tunnel deformation.( 3) The strength of high-strength steel grating is high,can provide a higher support security reserves. High-strength steel grids in the soft rock tunnel to show a good applicability.