全尾砂-废石混合回填膏体渗透特性试验研究

Experimental study of permeability characteristics of backfill paste mixed with unclassified tailings and waste rock

塌陷区混合回填膏体是由全尾砂、废石人工制备得到的复合宽粒级散体,其渗透性能直接影响到塌陷区回填体稳定性及次生灾害发生的可能性。采用自制的渗透性试验装置,研究了废石含量、废石粒径对混合回填体渗透系数的影响,并对回填体固有特征参数(粒径小于0.075、0.02 mm颗粒含量、不均匀系数uC、平均粒径)与渗透系数之间关联性进行了研究。试验结果表明,回填膏体渗透系数随废石掺量及粒径增大而增加,细粒效应显著。回填体中粒径小于0.075、0.02 mm颗粒含量对其渗透性影响至关重要,与渗透系数呈负指数关系。渗透系数随uC值增大而增大。当uC<20时,渗透系数增幅较大;当uC>20时,渗透系数增加趋于稳定。给出了混合回填体渗透系数定量方程,其结果与试验结果较为一致。

The mixed backfill paste for subsidence area is a kind of artificial compound granular media which has wide size fraction and is made of unclassified tailings and waste rock; its permeability performance directly affects the stability of backfill body for subsidence area and other secondary disasters occurrence. Based on homemade experimental apparatus of permeability, the effects of the content of waste rock, waste rock particle size on permeability coefficient of mixed backfill body, and the relevance between backfill paste’s inherent characteristic parameters （the content of particle size below 0.075 mm and 0.02 mm, non-uniform coefficient uC , mean particle size） and permeability coefficient are studied. Test results show that, with waste rock content and particle size increasing, the permeability coefficient of backfill paste increases;the fine particle effect is remarkable. The content of particle size below 0.075 mm and 0.02 mm in backfill paste has a crucial effect on permeability and has a negative exponent relation with the permeability coefficient. Permeability coefficient increases along with the uC values. When the uC value is less than 20, permeability coefficient increases sharply;and when the uC value is greater than 20, the increase in permeability tends to be stable. Then the quantitative equation of mixed backfill paste permeability coefficient is obtained, which is consistent with the test results.