Experimental investigation of the seepage failure between bulkheads and surrounding rocks in deep underground mines

摘要

This paper presents an experimental investigation of seepage failure between water retention bulkheads and surroundingrocks. Water retention bulkheads are commonly used to prevent and control water inrush in underground mines. However,water seepage or even water inrush still occurs because bulkheads are traditionally designed for structural integrity and stabilitywith little consideration of seepage failure and the permeabilities of surrounding rocks. To address the issue of waterseepage in the strata surrounding the bulkheads, a scale model test was developed to simulate the seepage failure process inhomogeneous surrounding rock and surrounding rock with a fractured zone with high water pressures in deep undergroundmine. The results revealed the occurrence of seepage and changes of pore water pressure in the surrounding rocks, whichwere first divided into five stages due to the blocking effects of bulkheads. Seepage or seepage failure can occur through andaround bulkheads, especially when a fractured zone exists around the roadway. Therefore, a criterion for predicting seepagefailure was put forward and verified with experimental results. Specifically, when the ratio of the critical hydraulic gradientto the stable hydraulic gradient is greater than the water retaining safety coefficient of the bulkhead, the bulkheads will failto retain water. The safety coefficient is determined to be 0.6 according to the statistics of bulkhead engineering practices inunderground coal mines. This work indicated that seepage stability must be demonstrated when designing and constructinga water retention bulkhead, in addition to considering the mechanical strength and stability.