高砾石土心墙坝硬岩过渡料精细爆破法开采研究

Method of Fine Blasting and Mining of Hard-rock Transition Material for High Gravelly Soil Core Rockfill Dams

高砾石土心墙堆石坝过渡料对坝体的变形协调至关重要,要求过渡料级配连续良好,规范规定最大粒径宜≤300 mm.过渡料的平均块度d50一般仅为15～55mm,当料源为花岗岩等硬岩时,爆破开采难度大.结合长河坝水电站过渡料开采爆破试验,介绍了通过适当增加爆破单耗、合理布置炮孔间排距以及采用微差顺序起爆网路等技术,可以通过爆破法直接开采过渡料,并结合试验成果对Kuz-Ram模型中不均匀指数进行了修正.完整致密坚硬岩体爆破开采过渡料应选择可爆性较好的区域,爆破器材选择高威力成品乳化炸药以及高精度雷管等,可通过降低单孔装药量,加密炮孔间、排距和控制台阶高度等,来控制爆破块度.试验研究成果对有严格级配和粒径要求的堆石坝坝料爆破开采有一定的参考价值.

Transition material is crucial to the deformation compatibility of high gravelly soil core rockfill dam.The gradation of transition material is required to be continuous,and the maximum particle size should be less than 300 mm according to specification.Blasting excavation is quite difficult because the average block size （d50） is small （only 15 mm-55 mm）,especially when the source material is granite or other hard rocks.By appropriately increasing the unit explosive consumption,arranging reasonable hole distance between gun holes,and adopting tinny difference sequence blasting network,the transition material of Changheba hydropower station could be directly obtained by blasting excavation method.According to the test results,a method is proposed to correct the uneveness index of Kuz-Ram model.To control the block size of the transition material blasting excavated from sound rock,the blasting area should be well chosen,and high power emulsion explosive,high-precision detonator and optimized blasting parameters could be adopted.This research provides reference for blasting excavation of rockfill dam material which is strictly required in particle size distribution.