Study on statistical damage constitutive model of roadside backfill for the gob-side entry retaining

摘要

In order to achieve the scientific concept of no coal pillar coal and gas extraction, the gob-side entry retaining are adopted, the key to apply the gob-side entry retaining is to maintain the stability of roadside backfill, the roadside backfill is of damage mechanical properties in the deformation process, so it is essential to determine damage instability criterion of roadside backfill.With Drucker-Prager yield criterion and weibull statistical distribution theory, based upon random distribution of defects inside the roadside backfill material, statistical damage constitutive model is established.To the destruction rate of mesoscopic unit of roadside backfill as the damage variable, based upon strain equivalence hypothesis, the damage constitutive of roadside backfill is derived, and the damage instability criterion of roadside backfill is determined.Using minimum potential energy principle, the mechanism of instability is illustrated, and the formula of limit load is derived.Research and analysis shows that the damage of roadside backfill is closely related to the stress of the roadside backfill, the strength of roadside backfill and the accumulation of damage evolution, the greater the strength of roadside backfill, the greater limit load, the smaller the damage of roadside backfill, and easier to maintain the stability of roadside backfill.With the increase of the damage of roadside backfill, the ability to storing elastic strain energy decreases, the total potential energy of the system shows an increasing trend, roadside backfill will lose stability when the total potential energy of the system is at the maximum.The project shows buckling failure will occur when the damage variable is about 0.8843.