Reasonable width determination method for gob-side entrydriving narrow coal pillar based on fracture evolution

Abstract

The invention discloses a reasonable width determination method for a gob-side entrydriving narrow coal pillar based on fracture evolution. The method comprises the following five steps: observing roadway deformation and coal pillar fracture distribution characteristics on site; establishing a UDEC-Trigon numerical model to match with on-site condition to determine model parameters; reversing an evolution rule of fractures in different coal pillar widths; determining the reasonable coal pillar width fracture evolution penetration; and finally providing a high pre-stressed anchor and anchor cable technology to control stability of the coal pillar. By adopting a damage factor for quantifying assessment of fracture evolution penetration to finally determine the optimum reasonable width of thegob-side entrydriving narrow coal pillar, inner fractures of the coal pillar in a service period are not penetrated, and gas in a goaf can be isolated effectively while the coal pillar is carried stably.

Description

technical field [0001] The invention belongs to the technical field of coal mining, and in particular relates to a method for determining the reasonable width of a narrow coal pillar in a gob-side roadway based on the evolution of cracks. Background technique [0002] Coal pillars can carry the overlying strata to prevent surface subsidence, isolate water and harmful gases in gobs, and maintain the stability of mining roadways, which play a key role in coal mining. Gob-side driving is to excavate the roadway along the edge of the goaf, and leave a narrow coal pillar of 5-10m to maintain the stability of the roadway. Although yield coal pillars have been successfully applied underground, there is no uniform design principle for coal pillar width. [0003] Coal pillars in coal mines do not occur naturally but are formed during mining activities and subsequently experience the effects of face mining. Previous studies were based on elastoplastic theory and limit equilibrium th...

AI Technical Summary

Problems solved by technology

Previous studies were based on elastoplastic theory and limit equilibrium theory, and the coal pillar was regarded as a homogeneous material to analyze the stress distribution in the coal pillar, the width of the plastic zone and the elastic zone, as well as the size of the bearing capacity, and the actual situation. There are large differences; traditional numerical simulations mostly use constitutive models such as Mohr Coulomb and strain softening to study the macroscopic failure of coal pillars, which cannot reveal the essential role of crack expansion on coal pillar failure

Coal pillars that are too wide will not only waste coal resources, but also affect the efficiency of roadway excavation; while coal pillars that are too narrow may cause cracks to penetrate and cause safety accidents

At present, the expansion of internal cracks is not considered when designing the width of coal pillars. If the cracks in narrow coal pillars penetrate, negative pressure ventilation in high-gas mines may cause gas in the goaf to enter the gob-side roadway, causing gas to exceed the limit. poor sex

Images