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前言在进行扩底打桩施工中,使用了多种钻具。本文将介绍一种滑降式扩底钻具。作为OMR/A施工法和HAMAN施工法的滑降式扩底钻具,分别于1980年2月和1981年1月取得日本建筑中心的评定,并已应用于许多施工当中。以下叙述其构造和性能。一、基本构造上述施工法是利用反循环法进行扩底钻进的。该扩底钻具与钻杆相连旋转钻进,并排出钻屑。在该钻具的中心部位有一钻屑排出管,机身上备有一斜向滑降导架,滑降式钻头可沿导架滑降(见图1)。滑降导架同准备扩底的钻孔孔壁呈一定角度,在扩底钻进时,边旋转边使扩底钻头滑降,这样便形成一定尺寸的锥形扩底孔,其土砂被一个与钻杆连接的抽吸管从入口处吸入并排
Foreword A variety of drilling tools were used in the pile-drilling. This article will introduce a slide-down type bottom-drilling tool. As a bottom-down drilling tool with OMR/A construction method and HAMAN construction method, it was evaluated by the Japan Architecture Center in February 1980 and January 1981, respectively, and has been used in many constructions. The following describes its structure and performance. First, the basic structure of the above construction method is the use of reverse circulation method to expand the bottom of the drilling. The boring tool is connected with the drill pipe to rotate and drill cuttings. At the center of the drill, there is a cuttings discharge pipe, and an oblique slide guide is provided on the fuselage. The slide-down drill bit can slide down along the guide frame (see Figure 1). The slide guide is at an angle to the wall of the hole to be drilled. When the bottom hole is drilled, the bottom drill bit is allowed to slide down while rotating. This results in a conical bottomed hole of a certain size. Rod-connected suction tube sucks side by side from inlet