明堂山隧道断裂破碎带涌水概念模型与止水承压特征

A Conceptual Water Inflow Model and Characteristics of the Hydraulic Pressure of Water-Stopping Points in the Mingtangshan Tunnel's Fractured Zone

隧道建设中涌水问题处理不当将会对当地生态和社会环境产生重大影响。文章选取明堂山隧道施工过程中的典型涌水段,探讨了断裂破碎带涌水水文地质概念模型,并在典型涌水断面开展了小尺度涌水点止水承压试验,提出了开挖前天然状态与开挖干涉后断裂破碎带裂隙水的3种分布状态模型。隧道涌水后,丰枯水期不同,可伴随表层风化裂隙上层滞水饱和带的形成或消失;涌水点止水承压后水压迅速升高,但随后增大趋势减缓,并可用对数模型刻画;单个涌水点附近形成水头降落漏斗,在止水承压后可恢复至与其它联通涌水点平衡,时长7 d的监测结果表明,选定涌水点止水承压24 h后即达水压稳定状态。

Considering that improper treatment of water inflow during tunnel construction may seriously affect local ecological and social environments, and using a typical water-inflow section of the Mingtangshan tunnel as an example, this paper proposes a conceptual hydrogeological model for water inflow in a fractured zone based on a small-scale test for hydraulic pressure at a water-stopping point on a typical section. It presents three fissure water-distribution models for the fractured zone before and after excavation. The results show that： 1） a perched water saturated zone in the surface weathered fissure rock layer will appear or disappear after water inflows with the coming of the wet season or dry season; 2） the hydraulic pressure of the water-inflow point increases rapidly after water stopping and then slows down, which can be reflected by a logarithmic model; 3） a water-head depression cone is formed near a single water inflow point, and a balance will be reached by connecting to other interlinked points of water inflow after water stopping; and 4） seven-day monitoring indicates that a stable hydraulic pressure can be achieved after 24 hours of water stopping.