渗流力和结构面水弱化作用下裂隙岩体边坡块体的稳定性

裂隙岩体渗流是影响岩体稳定性的重要因素之一。裂隙中的流体流动不仅会产生渗流力，而且会降低裂隙面的强度，致使边坡失稳、隧道塌方等事故频发。为揭示渗流作用对裂隙岩体边坡块体稳定性的作用机理，基于关键块体理论，提出一种同时考虑渗流力和结构面水弱化作用的稳定性分析方法，其中，渗流力基于渗流理论和统一管网法计算，结构面水弱化根据经验公式确定。以某岩质边坡为例，采用该方法对边坡在渗流作用下的块体稳定性开展研究。研究结果表明，渗流力与结构面水弱化作用对裂隙岩体边坡块体稳定性的作用方式不同，渗流力既会改变块体的抗滑力又会改变块体的滑动力，对块体稳定性的影响较为复杂，包括改变块体的稳定状态、滑移面、失稳形式；结构面水弱化只降低块体的抗滑力，进而降低块体的稳定性，不改变块体的失稳形式。此外，对于裂隙边坡工程，通常存在一个最危险渗流压力值。

Block stability of fractured rock slope under seepage pressure and fracture water weakening

Fluid flow in fractures is one of the important factors affecting rock mass stability. The fluid in the fracture not only produce external pressure but also weaken the fracture strength. Therefore, engineering accidents including slope instability and tunnel collapse frequently occur. In order to explore the mechanism of seepage on the block stability of fractured rock masses, this study proposes a stability analysis method considering both seepage force and effect of fracture strength weakening by water, based on the Key Block Theory (KBT). In this method, the fluid pressures in fractures are simulated by Unified Pipe-network Method (UPM), and the relationship between fracture strength,s weakening and fluid pressures is determined by an empirical formula. This method is adopted to study the influence of seepage on the stability of a fractured rock slope. Results show that the action modes of seepage pressure and fracture water weakening on slope stability of fractured rock masses are different. The seepage force affects both the anti-sliding force and sliding force of the block. Therefore, the influence of seepage force on the block stability is more complicated, including changes of the block stability states, sliding surface, and the instability pattern. Fracture water weakening only reduces the anti-sliding force of blocks, and then reduces the stability of block, while not change the instability pattern of unstable block. Moreover, there is generally a critical pressure which is the most dangerous for rock slope engineering.