从五十年代起,水文地质工作者在第四纪松散地层中常应用大口径(一米左右)冲击钻机(CZ—30;CZ—22;CZ—20型)钻进。为了保证孔壁不坍塌,操作者经常采用稠泥浆(比重、粘度偏大),为了省事甚至直接往孔内倒入粘土,利用钻具在孔内活动自制泥浆,这就更加大了泥浆的稠度,甚至 Since the 1950s, hydrogeologists have often used large diameter (about one meter) impact drilling rigs (CZ-30; CZ-22; CZ-20) to drill in loose Quaternary formations. In order to ensure that the hole wall does not collapse, the operator often uses thick mud (specific gravity, viscosity is too large), in order to save or even directly into the hole into the clay, the use of drilling tools in the hole activity homemade mud, which even greater mud consistency ,even