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我队自1977年以来,在四川境内开展砂金普查找矿工作,迄今已投入砂钻工程二万余米,通过多年的实践,我们认识到,砂钻施工的特点在于: 1.根据砂金矿的赋存条件,施工钻孔普遍较浅.加之目前受开采技术条件的限制,施工孔深很少超过30米.由于孔浅,砂钻施工周期短,搬迁频繁; 2.砂钻施工中,所取出的砂样为松散物(冻土层施工例外),因此要求施工的全过程保持外套管超前钻进并护壁,然后在套管内取样.钻进与取样成为两个独立进行的工序,且取样所耗费的时间往往大于外管钻进的时间; 3.在松散砂砾层中,外管钻进除遇有大砾石须冲击(回转)破碎外,一般不存在破碎岩石的过程; 4.砂金粒度一般都非常小,为了保证取出样品的准确性,在整个施工过程中不充许使用冲
Since 1977, our team has carried out the gold prospecting and prospecting work in Sichuan Province. So far, more than 20,000 meters of sand drilling projects have been put into operation. Through years of practice, we have realized that the characteristics of sand drilling are: Due to the shallow hole, the construction period of sand drilling is short and the relocation is frequent; 2. During the construction of sand drilling, the construction drilling is generally shallow, The sand sample taken out is loose (exception to the construction of the frozen soil layer), so that the whole process of construction is required to keep the outer casing ahead of drilling and retaining the wall, and then sampling in the casing.Drilling and sampling become two independent processes, and Sampling time is often greater than the outer pipe drilling time; 3. In loose gravel layer, the outer pipe drilling except in the case of large gravel to be shock (rotary) broken, there is generally no broken rock process; 4. Gold The particle size is generally very small, in order to ensure the accuracy of the sample taken out, not allow the use of red throughout the construction process