MULTISHAFT FOUNDATION IMPROVING MACHINE

PURPOSE:To improve the strength of foundation by providing two pairs of auxiliary improving shafts severally having an axial center at mutually opposite positions in straight lines mutually crossing at right angles with the axial center of a main improving shaft taken as a center, and constructing an auxiliary improving pillar in a space between main improving pillars for unifying the main and the auxiliary pillar. CONSTITUTION:The axial centers of each one pair of auxiliary improving shafts 200, 300 are severally positioned in two mutually perpendicular straight lines having the axial center of one or more main improving shafts 100 as a center. The areas of circles drawn by excavating blades 210, 310 and the area of a circle drawn by an excavating blade 110 are partially overlapped each other. In the case of foundation improvement, an about square improving pillar consisting one main improving pillar and auxiliary improving pillars at four corners is formed by only once execution. In the case where sediment excavated by the shaft 100 is mixed with solidifying agent and stirred, the sediment excavated by the shafts 200, 300 is mixed and stirred together. Similar work is also executed in order at adjacent positions. Thus since the foundation can be perfectly and wholly improved and easily lappedly executed, the strength of the foundation and resistance against earthquake horizontal force can be enlarged.