The main parameters of the rock reamer operation control are the push-pull force applied to the reamer by the drilling rig (pull force during reverse reaming, thrust force during forward reaming), or drilling pressure, rotational speed, and mud pumping during reaming. The control points are as follows:
1. Different diameters and different types of rock reamer hole openers have different requirements on drilling pressure. Most rock layer reaming accidents are caused by excessive pursuit of reaming speed and excessive drilling pressure.
2. Rotation speed is another important control parameter for rock reaming construction. The speed referred to here is the speed at which the drill rig drives the drill rod to drive the reamer to rotate. The adjustment of the speed is mainly related to the hardness of the rock. When reaming soft rock, when the diameter of the reamer is ≤30", the recommended speed should not exceed 60Rpm; when the diameter of the reamer is greater than 30", the recommended speed should not exceed 40Rpm. When drilling in hard rock, the speed should be reduced accordingly, generally 10~40Rpm. Too low speed will reduce the efficiency of reaming, which is not economical; too high speed will cause abnormal wear of the reamer and even cause reaming accidents.
3. An important principle that should be followed in the rock reaming operation is: the harder the rock to be broken, the greater the drilling pressure required, and the lower the drilling speed required. At the same time, it should be noted that under the same drilling speed condition, the effect of the reamer with different diameters is different. The larger the diameter of the reamer, the greater the linear velocity of the outer edge and the more serious the wear.
4. When reaming the rock layer, it is also critical to ensure the pumping volume of mud. At this time, the main function of mud is to cool the reamer and carry drill cuttings. The actual pumping volume of mud should be determined after calculation based on the amount of drilling cuttings produced by each stage of reaming and the carrying capacity of the mud, and generally should not be less than 1m/min.
5. The construction method of the reamer entering the rock layer: When the rock reamer enters the rock layer from the soft soil layer or enters the hard rock layer from the soft rock layer, the operating point is to first slow down the reaming speed, reduce the drilling pressure, and wait for the reaming After the device body has completely entered the rock layer or hard rock layer, increase the WOB. If the drilling pressure applied during this process is too large, it is likely to cause jamming, thereby damaging the reamer, or at least shortening the life of the reamer bearing.
6. When performing graded reaming, be careful not to choose rock reamers with too similar diameters (gradient difference less than 4") for graded reaming, otherwise the reaming effect of the reamer will not be exerted on the one hand, and the diameter is too large on the other hand. Similar reamers are prone to the danger of being stuck by the rock layer during operation.