矿山采空区边坡动态稳定性评价方法

Dynamic stability evaluation method of mine goaf slopes

  • 摘要: 矿山边坡因采空区沉降引发的斜面岩土体崩塌破坏,是一种破坏力极强的地质灾害. 由于传统的稳定性评价方法未考虑采空区沉降造成的应力场变异,难以实现矿山边坡的动态稳定性评价,因而在矿山地质灾害预警预防方面存在诸多限制. 基于此,本研究针对矿山采空区滑坡的成因机制,建立了一套适用于矿山边坡的动态稳定性评价方法. 首先通过构建采空区沉降分析模型,计算采空区上方岩体的沉降范围及其产生的冲击作用力,分析沉降对坡体应力场的影响,并在此基础上对传统不平衡推力法进行修正. 案例分析结果显示,传统方法未考虑采空区沉降作用和锁固段的破坏情况,导致稳定性系数计算偏大,为1.355. 而改进方法通过考虑采空区沉降信息,计算得出锁固段稳定性系数为0.667,整体稳定性系数为0.979,与矿山采空区边坡实际破坏情况一致. 当沉降位移比(SHDR)大于0.73时,采空区边坡稳定性会发生明显变异,因而会在相对安全的工况下发生失稳破坏. 改进方法通过考虑采空区沉降作用和锁固段的破坏情况,可以更好地实现矿山边坡稳定性的评价,为矿区更好地应对类似地质灾害提供有效参考.

     

    Abstract: The collapse and damage of inclined rock and soil masses caused by subsidence in mining goaf areas pose serious geological risks. These hazards are not only highly destructive and widespread but also occur suddenly, endangering mine operations and human safety. Traditional stability evaluation methods often overlook the variations in thrust caused by the settlement of goaf blocks at the leading edge locking section, making it difficult to dynamically evaluate mine slope stability. This limits the effectiveness of early warning and prevention strategies for geological disasters in mines. To address these challenges, this study introduces a dynamic stability evaluation method tailored for mine slopes, targeting the landslide formation mechanisms in mining goaf areas. The first involves constructing a settlement analysis model for the goaf areas to calculate the settlement range of the rock mass above the goaf and the resulting impact forces. The proposed model helps analyze how settlement affects the stress field of slopes. Therefore, the traditional unbalanced thrust method is modified. During stability evaluation, the safety factor of the slope’s locking section under the subsidence effect of the goaf was analyzed. When the safety factor of the locking section (SFk) is less than 1, the residual strength needs to be considered to calculate the overall safety factor (SF) of the slope. If SFk exceeds 1, the section remains intact, allowing the SF to be calculated under original working conditions. The Jiweishan case in Wulong, Chongqing, illustrates the limitations of traditional methods, which neglected the settlement and locking section damage, overestimating the safety factor at 1.355. The improved method, accounting for these effects, found the locking section’s safety factor at 0.667, indicating damage and an overall landslide safety factor of 0.979. This finding aligns with the observed failure and instability mechanism of the mine goaf landslide. When the weight of the settlement slope at the rear edge is large, settlement causes instantaneous shear failure of the landslide locking section, substantially reducing the stability of the Jiweishan landslide. The settlement–horizontal displacement ratio (SHDR) of the slope is crucial in dynamic stability analysis for goaf areas. An SHDR greater than 0.73 indicates significant stability variations, leading to instability under working conditions previously deemed safe. This improved method offers a more accurate assessment of mine slope stability by considering goaf settlement and locking section damage, providing a valuable tool for managing similar geological disasters.

     

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