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问题1关于反循环钻孔作业法叙述如下,请您指出下面各项作业中哪一项是错误的.(1)适合于粘土、砂层作业;(2)当砂砾层、漂石层的最大粒径小于钻管内径的70%时,可以进行钻孔作业;(3)对硬粘土层不能进行钻孔作业;(4)对基岩可以进行钻孔作业.解答:反循环作业法是利用静水压稳定孔壁,用反循环水流钻削扬排泥土,但是,对地质的适应性必须充分予以注意.一般对粘土、粉土、砂层、硬粘土层及基岩等均能够进行钻孔作业,但是,对硬粘土层、基岩进行钻削时,必须安装特殊刀头,对漂石等块状物进行钻削时,由于粒径受钻管内径的限制,
Question 1 The following is a description of the reverse circulation drilling method. Please indicate which of the following items is wrong. (1) It is suitable for clay and sand; (2) When the gravel and boulders are the largest When the particle size is less than 70% of the inner diameter of the drill pipe, drilling operations can be performed; (3) Drilling work cannot be performed on the hard clay layer; (4) The bedrock can be drilled. Solution: Reverse circulation method is used The hydrostatic pressure stabilises the wall of the hole and uses reverse circulation water to drill the mud. However, the geology must be fully noted for its suitability. Generally, clay, silt, sand, hard clay and bedrock can all be drilled. Hole operation, however, when drilling hard clay and bedrock, a special cutter head must be installed. When drilling blocks such as boulders, the particle diameter is limited by the inner diameter of the drill pipe.