Stability of shallow karstic caverns in blocky rock masses
Stability of shallow karstic caverns in blocky rock masses
复制标题
DOI：
10.1016/j.ijrmms.2010.09.014
复制
发表时间：
2010-12
影响因子：
7.2
通讯作者：
Y. Hatzor;I. Wainshtein;D. Mazor
中科院分区：
文献类型：
--
作者：
Y. Hatzor;I. Wainshtein;D. Mazor
探讨了地下开口跨度和所需的覆盖高度之间的限制关系，以稳定的块状岩体的特点是网络的水平层面和垂直节理。了解这种关系是至关重要的岩溶地区的开采开挖设计，通常遇到的碳酸盐岩岩体。我们使用DDA方法对多个屋顶跨度与覆盖高度几何形状进行数值分析，以获得稳定和不稳定的开口几何形状之间的边界曲线。我们的研究结果表明，对于跨度高达18米的洞室，低覆盖高度与开口跨度之比h/B=0.33足以保证稳定性。对于大于18 m的跨度，对覆盖层高度的需求迅速增加，对于B= 26 m及以上，覆盖层高度似乎稳定在h/B=1.0。为了验证我们的数值分析结果，一个独特的案例研究进行了分析，其中一个40米跨度的岩溶洞穴，Ayalon洞穴，已被保存在一个活跃的露天矿在以色列中部的覆盖高度只有30米，从而使洞穴边缘稳定，根据我们的模型预测。事实上，有足够的证据表明洞穴的屋顶部分坍塌。我们的模型的预测能力进一步证实了使用两个额外的案例研究块状岩体，其中每个具有非常不同的力学参数，如完整的岩石强度，密度和变形，这表明我们的模型预测仍然有效，只要岩体保持一个“块状”的结构配置。
The limiting relationship is explored between underground opening span and required cover height for stability in blocky rock masses characterized by a network of horizontal bedding planes and vertical joints. Understanding this relationship is crucial for the design of mining excavations in karstic terrain as typically encountered in carbonate rock masses. We perform numerical analysis of multiple roof spans vs. cover height geometries using the DDA method to obtain the boundary curve between stable and unstable opening geometries. Our results indicate that for cavern spans of up to 18m a low cover height vs. opening span ratio of h/B=0.33 is sufficient for stability. For spans greater than 18m the demand for cover height rapidly increases and it appears to stabilize at h/B=1.0 for B=26m and above. To validate our numerical analysis results, a unique case study is analyzed wherein a 40m span karstic cavern, the Ayalon cave, has been preserved below an active open pit mine in central Israel with cover height of only 30m, thus rendering the cave marginally stable according to our model prediction. Indeed there is ample evidence of partial collapse of the roof in the cave. The predictive capability of our model is further confirmed using two additional case studies in blocky rock masses, each of which possesses very different mechanical parameters such as intact rock strength, density, and deformability, suggesting that our model predictions remain valid as long the rock mass maintains a “blocky” structural configuration.