高地应力软岩隧洞衬砌结构受力及强度安全系数研究

深埋条件下的高地应力软岩隧洞衬砌结构受力与一般隧洞不同,为探明其力学响应特征,依托实际工程对锚杆轴力、钢拱架应力及初支与二衬之间的接触压力进行现场测试,基于强度折减原理,采用有限差分软件Flac3D分析围岩稳定性和二衬受力后的强度安全系数。分析表明:高地应力环境下边墙部位锚杆发挥拉拔力作用明显,锚杆中性点随围岩塑性区发展有向围岩深处移动的趋势;钢拱架以受压为主并能立即发挥支护作用;在保证围岩稳定的条件下,二衬将承担12%的围岩压力,且受力集中的墙脚处二衬强度安全系数最小。

STUDY OF MECHANICAL CHARACTERISTICS AND STRENGTH SAFETY FACTOR OF TUNNEL LINING STRUCTURE FOR WEAK SURROUNDING ROCK IN HIGH GEO-STRESS ZONE

Mechanical characteristics of support structure for weak surrounding rock of deep burial tunnel in high geostress zone are different from general tunnels. To study the response mechanism of tunnel lining mechanics,an in-situ experiment was carried out to investigate the axial force of bolt,steel frame stress and surrounding rock pressure.Based on the theory of strength reduction,the stability of surrounding rock and the safety factors of load bearing liners were researched by finite difference software of Flac3 D. Research found that the bolts located at the sidewall beard a greater tension and its neutral point of bolts had a trend to move to deeper rock with the expansion of plastic zone; the steel frame stress was dominated to bear pressure and could quickly play a supporting role; with an ensuring to the stability of surrounding rock,the lining would carry 12% of surrounding rock pressure,and the minimum safety factors were located at the foundation of the linings with a concentrated stress.