浅埋大断面黄土隧道初期支护研究

结合郑西客运专线大断面黄土隧道对比试验,研究分析了浅埋大断面黄土隧道初期支护中锚杆、格栅及型钢钢架的作用以及长期有争议的锚杆作用及钢架类型问题。试验结果表明:有锚杆拱顶沉降值是无锚杆拱顶沉降值的1.7倍,两者的水平收敛、土压力、钢架应力相差不大;格栅和型钢钢架各项试验数值也相差较小。因此,根据分析结果提出了"在浅埋老黄土隧道设计中取消拱部系统锚杆,采用格栅钢架,加强拱部锁脚锚杆设置"的建议。

Primary Support for Shallow Large Profile Loess Tunnels

Based on the in-situ comparative tests for large-profile loess tunnels on Zhengzhou-Xi'an passenger-dedicated railway,authors of the paper studied and analyzed the functions of rock bolts,latticed arches and steel arch ribs used for the primary support of shallow large-profile loess tunnels and some subjects of considerable debate about the function of rock bolts and the type of steel arches.Results of tests indicated that crown settlement of tunnels with rock bolts was 1.7 times as large as those without rock bolts;horizontal convergences,earth pressures and stresses in steel arches were about the same for two kind of tunnels and tested values for latticed arches and steel arches were also the same.In consequence,authors put forward the proposals: abolishing system rock bolts in the arch for the design of shallow old loess tunnels;adopting latticed arches;setting up abutment bolts at arch spring.