| 摘要 |
FIELD: mining. SUBSTANCE: stabilizing pillars are worked out of high density filling mixtures in stopes of the first sequence. As this takes place artificial stabilizing pillars are formed of Backfield in three stages. First it is compacting by gravity, then it is afterfilling, and solidifying the pillars along contacts. As this takes place stabilizing artificial pillars are worked on the base of loading parameters under conditions of volumetric compression as yieldable ore pillars with the strain being specific for this particular conditions. Besides increment of stress and level of maximum stress in ore massif adjoining the artificial pillar is measured. Then critical relaxation period is determined by the formula: T=τ/U (time), where τ- is maximum stress, Newton per square meter, "v" is stress increment, Newton per square meter per day. With relaxation period achieving critical value for conditions of particular deposit and method of excavation stress concentration in the massif is released. As this takes place, with stabilizing pillars erected of high-density Backfield, the first stage of pillar forming is terminated in 90 - 110 days. The third stage starts from finishing the afterfilling, and it is finished with sudden pressure increase in the system of injection resulting in back circulation of the compressing mixture. Besides, the high- density sladge-rock mixture of 2100 - 2300 kg/cu.m density is created under conditions of keeping appropriate ratio of large, small and fine size, with maximum size restricted within 30 - 40 mm due to limited capacity of high-pressure pipeline. Content of fine size below 0.025 - 0.05 mm reaches 30 - 40 % to exclude cement segregation and sledge coagulation. Content of size exceeding 1.5 - 2 mm is determined by the formula:, where d and d(mm) are boundary values of small and fine sizes respectively. EFFECT: effective control over rock pressure. 2 dwg |
