Development of design criteria for working under weak rock masses

这是作者在过去十五(15)年中为操作员开发设计工具而进行的研究的延伸。候选人小组已经开发了经验设计方法，并在世界各地的矿山设计中使用。这些主要是针对被归类为一般到良好的岩体而开发的。采矿业现在正在开采需要在更困难的条件下开采的矿石，比如在较弱的岩石下。最初为人工进场方法开发的“跨度设计曲线”确定了对于给定的岩体可以打开的临界跨度。它在很大程度上是基于RMR超过55%或Q值大于4.0的岩体，这些岩体基本上没有支撑。这项建议着眼于扩展数据库，以纳入软弱岩体，同时量化支架对整体设计过程的影响。目标是建立一个安全的工程工作环境，因为采矿直接发生在裸露的背部下方，对操作员造成最大的暴露。将特别侧重于加拿大的条件和做法，编制一个扩展的数据库。将从应力、结构和岩石等方面分析个别矿场的开挖情况，以评估后部稳定性，并为工程师制定标准，以确保工作场所的安全。对于不同的岩体，将根据矿山实际观测条件对破坏机制进行建模和校准。这将估计故障的深度，并因此估计可能作用在支架上的潜在载荷。这将导致不同支承类别的设计曲线。分析代码、经验代码和数值代码等工具将根据现场观测和测量进行校准，以得出可行的解决方案，用于针对给定支架类型的软弱岩体中的背部进行设计。

This is an extension of research performed by the author over the past fifteen(15) years in developing design tools for the operator. Empirical design approaches have been developed by the candidate's group that are employed in mine designs throughout the world. These have been developed largely for rock masses classified as being fair to good. The mining industry is now extracting ores that require mining under more difficult conditions such as under weaker rock masses. The original "Span Design Curve" as developed for man-entry methods  identifies the critical span that can be open for a given rock mass. It is largely based upon rock masses having an RMR in excess of 55% or Q greater than 4.0 that are largely unsupported. This proposal looks at extending the database to incorporate the weak rock masses along with quantifying the effect of support on the overall design process. The objective is to develop a safe engineered work environment as mining occurs immediately underneath the exposed back and causes the greatest exposure to the operator. An expanded database will be compiled with particular emphasis on Canadian conditions and practices. Individual mine openings will be analysed in terms of stress, structure and the rock mass in order to assess back stability and to develop criteria for the engineer to ensure a safe workplace. The failure mechanism will be modeled and calibrated to actual mine observed conditions for variable rock masses. This will estimate the depth of failure and consequently the potential loading that may act on the support. This will result in design curves for varying support categories. Tools such as analytical, empirical and numerical codes will be calibrated to site observations and measurements to arrive at a workable solution for purposes of design of backs within weak rock masses for a given support type.