Review of crown pillar investigations in a historic mine camp

Strategies for surface crown pillar design using numerical modelling – A case study

“…The appropriate FoS ranges can be identified from the database of crown pillar stability or surface subsidence inventory. Henning (2007) summarized from local experiences that some crown pillars have failed at FoS values around 2 (see Figure 2.2). Henning, 2007) The scaled span method was later improved by addressing various levels of allowable risk from the perspective of different stakeholders, as shown in Figure 2.3 (Carter, 2014).…”

“…Henning (2007) summarized from local experiences that some crown pillars have failed at FoS values around 2 (see Figure 2.2). Henning, 2007) The scaled span method was later improved by addressing various levels of allowable risk from the perspective of different stakeholders, as shown in Figure 2.3 (Carter, 2014). Along with this chart, a more systematic classification for assessing the acceptable risk of crown pillar failure was also proposed, as illustrated in Table 2.1.…”

“….1. The table divides the risk of crown pillar failure into seven classes with a minimum FoS and an estimated serviceable life span in each class Henning (2007). summarized from local experiences that some crown pillars have failed at FoS values around 2 (see Figure2.2).…”