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当普查时，尤其是初步和详细勘探砾石矿床时，只有地表揭露，是不能完成砾石品位的研究和储量的计算，在这样的情况下，就需要采用浅井、大口径的钻探和少量的深槽探。浅井的掘进通常采用正方形（1.25米×1.25米和1.5米×1.5米）或长方以（1米×1.5米和1米×2米）的断面，断面的选择应很据设计的井巷深度来确定。砂矿浅井必须支护，就是沙砾比较稳定时，每
When the census, especially the preliminary and detailed exploration of gravel deposits, only the surface reveals that the study of gravel quality and the calculation of reserves can not be completed, in which case it is necessary to use shallow wells, large diameter drilling and a small number of deep grooves Exploring Shallow wells are usually driven by square (1.25 m × 1.25 m and 1.5 m × 1.5 m) or rectangular (1 m × 1.5 m and 1 m × 2 m) cross sections. The cross section should be chosen according to the designed depth to make sure. Sand shallow wells have to support, that is, relatively stable gravel, each