A Possible Mitigation Strategy to Avoid the Collapse of Old

question 59

Multiple Choice

A possible mitigation strategy to avoid the collapse of old coal mine adits or tunnels is to fill them with sand to support the roof.This strategy was employed in old gold mines in Timmins,Ontario.What happened over time to make this strategy ineffective?

• A) Pore water pressures within the sand increased and caused liquefaction subsurface.
• B) Some of the sand washed away and no longer supported the tunnel roofs.
• C) The sand settled and compacted, leaving voids into which the roofs collapsed.
• D) The sand displaced subsurface water, raising the water table and flooding parts of the surface.
• E) The sand allowed water to flow freely through pore spaces, dissolving more material from the mine walls.

---

Definitions:

Environmental Influences

Environmental influences involve external factors and conditions that impact an individual's physical, psychological, and social development.

Sensitive Period

A point in development when organisms are particularly susceptible to certain kinds of stimuli in their environments, but the absence of those stimuli does not always produce irreversible consequences.

Synaptic Pruning

The process during brain development where extra neurons and synaptic connections are eliminated to increase the efficiency of neuronal transmissions.

Neurons

Specialized cells of the nervous system that transmit signals throughout the body; key components in the function of the brain, spinal cord, and peripheral nerves.