不同分布距离的软弱夹层对洞室稳定性的影响研究

A study of influence of weak interlayers distributed at different intervals on opening stability

软弱夹层等不良结构面对地下洞室的围岩稳定与支护结构安全起着决定性的作用,本文研究了顶部分布有软弱夹层隧洞的围岩稳定性与支护结构安全性,重点研究了夹层分布距离分别为0.2B,0.5B,1.0B(B为洞跨)3种情况,总结了夹层分布距离与洞周关键点位移、围岩应力、围岩塑性区的关系,分析了不同的分布距离下喷层的受力状况,并进一步探讨了常见围岩类型(II类、III类、IV类)中不同分布距离的软弱夹层对地下洞室围岩稳定性的影响,得出了不同分布距离软弱夹层对围岩变形、应力、支护结构受力影响的一些量化成果。研究成果可望对地下洞室选线(址)、支护系统优化以及施工有借鉴意义与指导作用。

Such unfavorable structural planes as weak interlayers play a decisive role to the stability of rocks surrounding underground openings in some cases and the safety of supporting structures. Using a FEM program FINAL of Austria that adopts a COJO element a perfect element to simulate the characters of weak interlayers, this paper has conducted systematic numerical tests to study the stability of a tunnel surrounded by rocks containing weak interlayers and the safety of supporting structures. In studying, the emphases are put on three situations where the interlayers are distributed at intervals of 0.2 spans, 0.5 spans and 1.0 spans respectively Some quantificational results about the influence of weak interlayers with those three different spacing intervals are summarized, especially the influence on the deformation, stress of stLrrounding rocks as well as the inner force of shotcrete supporting structure. These results have referential and guiding significance to the site selection and layout, the majorization of supporting system and the construction of underground openings of the same kind.