SIMULATION ANALYSIS OF CRACK EXTENDING PROCESS UNDER PORE HYDRAULIC PRESSURE IN THE DRILL OF COAL-ROCK STRATUM

摘要

The caving of thick and strong roof stratum causes tremendous rock pressure in mine. In order to control the rock pressure effectively, the thick and strong roof strata, of which the softening factor is relatively small, can be treated previously by hydraulic fracturing and low-high pressure water infusion, fracturing and softening method. The study of the crack path of the hydraulic fracturing and the infusion pressure is of great significance in measuring the ground stress and solving the engineering problems in the better way of the hydraulic fracturing. With the help of hydraulic fracturing method and Griffith law, the process of crack extension due to hydraulic pressure in rock mass abject to ground stress field was analyzed in mechanics, fracturing pressure in stages of crack occurrence and extending was presented. Moreover, the relationship of fracturing pressure of crack and distribution of ground stress field was elucidated as well as mechanical characteristic of surrounding rock. Analysis of pressure in the process of crack extending in the drill of coal mass was proceeded, as a result the guideline were presented for simulating test of hydraulic fracturing and water infusion softening in coal-rock stratum for the caving of thick and strong roof stratum.