The drilling efficiency of a small rotary drilling rig refers to the ratio of the total depth of the pile hole drilled to the total time spent in normal operation. The factors affecting the drilling efficiency of rotary drilling rig include hole depth, bore size, formation condition, tool selection and pipe type.
1. Influence of hole depth on drilling efficiency of rotary drilling rig
In the construction of rotary drilling rig, when the drill bit is filled with soil, it is necessary to lift the drill and unload the soil, and then the drill tool is lowered to the bottom of the hole. Obviously, the smaller the hole depth, the higher the efficiency. Drilling efficiency V=H1/(t1+t2+2H/V1) (m/h), where H is the footage per drill, m; t1, the time it takes to drill a bucket, h; t2 is the unloading time, h; H is the hole depth, m; V, is the lifting and running speed, m/h. From the above formula, it can be seen that when other parameters are unchanged, the larger H is, the smaller V is. When the hole depth exceeds 100m, the drilling efficiency will drop sharply; when the hole depth exceeds 120m, the drilling efficiency will be lower than that of other construction methods, and the accident rate will increase significantly. Therefore, it is recommended that other construction methods such as positive and negative circulation should be selected as far as possible when constructing ultra-deep holes.
2. Influence of aperture on drilling efficiency of rotary excavator
At present, the commonly used rotary drilling rig is a rotary drilling bucket, the barrel body is hollow, and the lower part has two entrance doors. During drilling, the ballast is cut from the bucket door into the barrel body through the drill teeth. Under the thrust of the lower ballast, the upper ballast gradually rises into the barrel until the barrel body is filled. The diameter of the drilling hole has two main effects on the drilling efficiency, one is the speed of the dirt entering the hopper door, and the other is the speed of the dirt rising in the barrel. First of all, the speed of ballast soil into the hopper door is related to the area of the hopper door. The larger the diameter of the hole, the larger the area of the hopper door, the greater the speed of the hopper door;
