Discussion Of The Technical Problems About Using Pneumatic DTH Hammer To Anchor Into The Hole

With the increasingly tense of using urban land, new construction of city hasgradually developed to the high-rise. The excavation of foundation pit has becamefrom the initial development of a few meters to ten meters, and then tens of meters,which must have a good supporting measures. At present, there are varieties of waysto support high-rise building foundation, but the coalition with pile wall and Anchorhas been used particularly extensively. DTH Hammer drilling technology has a veryimportant position, with its unique advantages in the anchor project of the excavationsupporting system, and its advantage is increasingly being recognized. Especially inthe loose and broken strata, gravel layer, the hole wall is easy to collapse with otherpore-forming process, so it got into the low efficiency, and impact the project cost andconstruction schedule. DTH Hammer Drilling has the prominent advantages but alsosome drawbacks.In this article, construction technique of anchor engineering has been introduced,and points that this step of anchoring into the hole is particularly important and mustchoose the right method. DTH Hammer with Casing Drilling Method for complexformation, such as gravel layer, easily broken strata, has high-quality and hard toappear collapse, which has been widely used in anchor construction. Then the holehammer drilling with pipe system has been analyzed systematically, including DTHhammer drilling theory, DTH with the structure and working principle of the tube drill,DTH Hammer drilling parameters, DTH Hammer drill pipe pressure. Summarizes theprevious methods about how to determine the maximum depth of DTH hammerdrilling with pipe and problems encountered in the drilling of DTH Hammer.This article focuses on the casing stress analysis, including the failuremechanism of the casing, the casing shoe shoulder stress analysis, stress analysis of casing thread, load distribution characteristics described. The finite element analysissoftware has been used to analysis the connecting thread of the pipe and thesimulation of casing, including comparison group analysis of different screw pitch,simulation model, the model boundary conditions and load, simulation analysis, andoptimization results analysis.Engineering practice verify that the DTH hammer drilling with pipe in brokenstrata, such as the gravel layer, has a good effect. And verify the drilling process withthe tube, if the casing thread damage, it will start from the root of the thread, and thefailure mode is shear failure, fracture. Casing with a special processing is to increasethe pitch, the casing thread force distribution is significantly improved and the generaldestruction is fatigue damage, the destruction of the form is grinding flat aftertripping.