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我们施工的广东大宝山矿区,地质构造复杂,表土厚度一般10～20米.其下为褐铁矿层,厚20～150米.矿层风化强烈,裂隙发育,矿体破碎,有的已风化成粉状,局部夹厚薄不均的高岭土层,遇水极易膨胀.下部是完整的斑岩或灰岩. 在钻进矿层的过程中,经常发生严重漏失,井壁掉块、坍塌及大量涌砂等现象,有时还发生超、缩径事故. 开始时,我们用清水洗并,不能维持正常钻进,报废了不少钻孔.后来改用一般泥浆护壁钻进,情况
The construction of the Guangdong Dabaoshan mining area, the geological structure is complex, topsoil thickness is generally 10 to 20 meters.And under the limonite, thickness of 20 to 150 meters.The mine is weathered strong, fracture development, ore body broken, and some have been weathered into Powder, local folder thickness uneven kaolin layer, easy to swell in water. The lower part is a complete porphyry or limestone .During the process of drilling into the seam, often a serious loss, borehole collapse, collapse and a large number of Chung Sand and other phenomena, and sometimes also occurred ultra, reduced diameter accident.At the beginning, we wash with water and can not maintain normal drilling, scrapped a lot of drilling, and later switched to the general mud retaining wall drilling, the situation