Special Formation Of Large Diameter Bored Pile Construction Technology

Because of the development and the requirement of construction, large diameter concrete pile is used commonly for its excellent feature. The problems with which the drilling confront in solid rock or in thick loose sand-pebble layer are lowly efficient, hole collapse. And the pile concrete is bad quality when it is poured under water.So we must chose the torque force and the hoist of the drill equipment for high drilling efficient, meanwhile ,we must be care of the equipment safe and of the remove of the rock residue. The oil field pulp is the first choice for it good feature, which can make drilling efficient, prolong the live of the drilling equipment, and make hole wall smooth and straight. The circulatory system of the pulp is reverse direction and the hob bit scatter at the plate as double helix for the remove of the rock residue. The drilling technology parameters are low pressure and low rotate speed.Leak of pulp, low efficiency and fall down of hole wall are the common problems when we drill in thick loose sand-pebble layer. Because of the complex nature of the sand-pebble layer, there is not a common good drilling method at present when we drill in this layer. We have used the lash-clutch and lash method, pump-reverse-direction and large diameter hob bit process to construct to engineering, which are very good.The factors that effect the concrete pile's quality are several. For the good pile quality, we must organize the process carefully before we start pour concrete. During the pouring concrete, we must control the concrete's quality, put the steel cage the place where it designed to be and pour ample concrete in the first pouring process. Ifthe pile quality is bad, we must remedy it by means of efficient method, for example inject cement pulp. We must exploit and develop the measure method to surrey the pile quality efficiently at present.