These drill pipe bit fishing methods
In the process of laying large diameter pile foundation of rotary excavator, the accident of burying hole collapse and holding drilling occurs from time to time, but the cause of rotary excavator accident, accident situation and site conditions are not the same, so the measures taken are not the same, sometimes it may be necessary to use several treatment methods. Xiaobian focuses on the description of drilling processing methods, and a detailed description of the processing tools, hope to communicate with peers.

After the occurrence of buried or held drilling accident, the mud performance should be adjusted in time to control the expansion of the accident, and the reasons should be analyzed in time to take corresponding measures, so as not to miss the best treatment opportunity. The treatment of buried drilling can be summarized as “clear, penetration, top, blasting, expanding, fishing, smashing, digging” and other methods and steps.

First, the treatment of sediment

“Clear” namely clear slag wash hole. Slagging can be carried out by positive and negative circulation, high spraying or well washing pipe air compressor. Slagging should be determined according to the stratum and the quality of mud and the equipment used to clear holes, so as to avoid the occurrence of secondary hole collapse accidents in the process of dredging. Use air compressor to wash the hole.

Two, the fishing of drill pipe bit

(1) In some cases, the key to deal with the buried drilling accident is to dredge the channel between the bottom of the hole and the upper part of the bit, so that the bottom and the upper part of the bit form a connector to avoid the piston effect, which is called “penetration”. In order to form a connector, generally several holes deeper than the accident hole are punched in the hole edge, and high-pressure rotary jet is used for pendulum spray. For path formation, turning the power head simultaneously increases the main line lift, potentially lifting the drill pipe and bit together. Some treatments use a reverse circulation drill combined with a reaming bit.

(2) “top” that is, jack top drill pipe, is the most commonly used force method to deal with drilling. Using the jack requires a solid platform and a welding jack application plate on the drill pipe. With 3cm ribs and drill pipe welding, top plate and ribs and drill pipe welding firm, and 2 pieces of top plate connection. The I-beam adopts 60x100cm specification and is connected by connecting plates. The jack control system should be linked and pressurized. Generally, the maximum load that the upper part of the drill pipe can bear is about 180kN. After the linkage pressure of the jack is pressed to 150kN, the pressure should be gradually increased, and the pressure should be stopped for about 1h after every increase of 3 to 5kN, waiting for the creep effect of the soil layer to play. Turn the power head while applying pressure. The result of using jack may have several kinds: first, the drill pipe of the drill bit is all pushed out; Two is the drill cap or door damage, drill pipe together with the destruction of the drill head out; Three is the drill pipe inner rod clamp ring or direct top broken, the inner rod and the drill bit in the hole; Fourth, the drill pipe is broken from the old crack, part of the drill pipe and the drill bit in the hole.

(3) “blasting” means hole bottom blasting. If it can not be lifted after washing the hole, the drill bit can be damaged by explosive positioning blasting and the drill pipe can be raised. Generally, the foundation pile holes used in this method to deal with accidents are close to the design depth, and can meet the bearing capacity requirements after design verification, and can be directly perfused after blasting.