What Should Be Paid Attention To In Dth Hammer Construction

  • During the pilot hole drilling process of DTH Bit, sometimes the drill rod may be stuck due to the collapse of the hole, insufficient water pressure, power failure, etc. after the accumulation of ballast in the hole, or the drill rod after the drill rod is broken during the pilot hole and reaming construction process The drill bit is stuck in the hole. These situations are quite difficult to deal with, and they occur frequently. They belong to the difficulty and key points of the DTH Bit piloting method. Here, Zhuoli will talk about some experiences based on experience.

    ① stuck in the process of pilot hole drilling

    We have adopted several methods for processing, one of which is to use high-pressure water to forcibly punch the hole. During the punching process, the drill is started to rotate the drill rod until the drill rod rotates and rises. Another method is to manually drill the pilot well to penetrate the pilot hole from the bottom up when the pilot hole is close to the lower flat hole, and punch the hole with high-pressure water after penetration.

    ②Drilling during reaming

    During the reaming process, due to the break of the drill rod, if the reaming drill bit is stuck in the expanded hole, it is very dangerous to handle it from below. Therefore, we consider to proceed from the pilot hole above. The first method: After connecting the drill rod, use the drill rod to apply pressure to the drill bit to make it fall naturally to the lower flat hole. The second method: send explosives into the stuck part of the drill bit through a wire rope at the orifice, and shake the drill bit to the lower flat hole after detonation. In this method, the amount of explosives is controlled at 5-8kg each time, and the drill bit will not be seriously damaged.

    ③Drill pipe fracture during pilot hole construction

    Some long-term used drill pipes may break during pilot hole drilling and reaming. DTH Hammer has a single drill pipe with a length of 1m and a weight of 180Kg. After the drill rod is broken, if the drill rod is not taken out, on the one hand, the drill rod and the drill bit will be lost, resulting in economy. On the other hand, holes have to be remade, and some special parts are not allowed to be remade. Therefore, how to fish the drilling tool has become a difficult problem in the DTH Hammer pilot method. For this reason, we invented a drill rod fishing device. The principle of the drill rod fishing device is the same as that of the expansion bolt. The upper part is connected with the drill rod by a straight thread, and the lower part is a conical sleeve. It can directly enter the broken drill rod during the advancement. After entering the inner wall, the vertebral sleeve will open during the lifting process of the overshot, and it will be tightly connected with the inner wall of the broken drill rod.

    After the drill rod is lifted to the hole and fixed with a drill clamp, the drill rods are taken out one by one. The overshot can lift more than 40 tons of weight at a time. That is, it can extract more than 200m drill rod length. Basically meet the drilling requirements.