卡姆奇克隧道岩爆的力学机制及主动防控技术

Mechanical mechanism and active control technology of rockbursts in Kamchik tunnel

以中亚第一长隧--乌兹别克斯坦卡姆奇克隧道为依托,在隧址区地应力特点、岩爆过程及特点综合分析的基础上,建立岩爆发生的力学模型,并在此基础上提出了主动控制岩爆的超前支护技术。研究表明:卡姆奇克隧道岩爆主要发生在拱顶附近,这主要是由于隧址区地应力最大主应力为水平方向且与隧道轴线接近垂直,隧道开挖后拱顶的切向应力最大的受力特点决定的;岩爆发生过程可分为拱顶围岩劈裂成板、岩板脆性断裂成块和块片弹射3个阶段;岩爆力学模型可简化为拱顶层状薄板在水平力作用下的脆性断裂失稳,岩板脆性断裂失稳的临界水平应力scr与岩板无支承长度L的平方成反比、与岩板厚度t的平方成正比,该力学模型可很好地解释卡姆奇克隧道岩爆的发生特点及主要表现特征。在此基础上,研发了一种通过减少拱顶岩板无支承长度、提高岩板厚度,从而提高岩板脆性断裂失稳临界应力,进而主动防止和减弱岩爆的超前支护技术,并在卡姆奇克隧道得到了广泛使用,取得了很好的岩爆防治效果。

Based on the comprehensive analysis of the geostress characteristics,rockburst process and characteristics of the Kamchik tunnel known as the longest tunnel in Central Asia,a mechanical model of rockbursts is established,and an advanced support technology for active rockburst controlling is proposed. The study shows that,due to that the maximum principal stress of the geostress in the tunnel site is horizontal and close to the tunnel axis and that the tangential stress of the vault is maximal after tunnel excavation,rockbursts mainly occur near the vault in the Kamchik tunnel. The process of the rockburst can be divided into three stages including splitting of the vault rock,brittle fracturing of rock slabs and block ejecting. The mechanics model of rockbursts can be simplified as brittle fracture instability of a bedded rock plate of the vault under horizontal forces. The critical horizontal stress scr of the brittle fracture instability of the rock plate is inversely proportional to the square of the unsupported length L of the rock plate but proportional to the square of the thickness t of the rock plate. The mechanical model can well explain the occurrence and main performance characteristics of rockbursts in Kamchik tunnel. On this basis,an advanced support technology by reducing the unsupported length of the vault slab and increasing the thickness of the rock slab to increase the critical stress of brittle fracture instability,was developed for active preventing and weakening rockbursts. Applications of the technology in Kamchik tunnel indicate that the effect is remarkable.