Abstract: A modified ground for an underground water cut-off wall, landslide protection wall, or a foundation pile, etc., is formed in an earthen foundation by an excavator having at least one rotary shaft in accordance with the following method. The rotary shaft includes a bit on a lower end thereof and at least one nozzle for jetting a consolidating fluid which is disposed upwardly of the bit. The method comprises an excavating step for forming a hole in the earthen foundation and a withdrawing step of the rotary shaft from the hole. That is, in the excavating step, the rotary shaft is advanced into the earthen foundation to form therein the hole while rotating the rotary shaft without jetting the consolidating fluid from the nozzle until the hole is excavated to reach a predetermined depth.

Abstract: A modified ground, for example, an underground water cut-off wall, landslide protection wall, or the like, is formed in an earthen foundation with the use of an excavator having at least one rotary shaft. The rotary shaft comprises a bit provided at a bottom end thereof, a stirrer having an expandable stirring wing disposed upwardly of the bit, and at least one nozzle for jetting a consolidating fluid in a downwardly diagonal direction. The stirring wing is capable of selectively taking an expanded form and a reduced form to vary an outside diameter of the stirrer about the axis of the rotary shaft. The nozzle is disposed upwardly of the stirrer such that the consolidating fluid jetted from the nozzle collides with the stirring wing in the expanded form. In the present method, the rotary shaft is inserted at a predetermined depth in the earthen foundation to form a hole therein while keeping the stirring wing in the reduced form without jetting the consolidating fluid from the nozzle.

Abstract: A cast-in-place concrete pile essentially consists of a lower concrete layer having fibers intermixed therein and an upper concrete layer having reinforcing elements. The lower portions of the reinforcing elements are embedded in the lower concrete layer to increase the bonding strength between the lower and upper concrete layers. The cast-in-place concrete pile of the present invention is constructed according to the following method. That is, an excavated hole is firstly formed in the ground. The reinforcing elements are placed at the upper side of the excavated hole, and then concrete including the fibers is cast into the excavated hole until the lower portions of the reinforcing elements are embedded in thus cast concrete, so that the lower concrete layer is formed. Continuously, concrete is cast onto the lower concrete layer in the excavated hole to form the upper concrete layer.

Abstract: For constructing a pillar in an earthen foundation, a consolidating fluid is sprayed inside the earthen foundation from consolidating fluid spray nozzles provided on a rotating shaft, and then the consolidating fluid and the soil of the original foundation are stirred and mixed. The consolidating fluid spray nozzles which spray the consolidating fluid approximately horizontally are provided on the rotating shaft. The pillar is formed in the earthen foundation by stirring and mixing together the consolidating fluid and the soil of the original foundation in such a way that the rotating speed of the rotating shaft is faster for clayish soil than for sandy soil, the pressure from the consolidating fluid spray nozzles is higher for clayish soil than for sandy soil, and the penetration speed of the rotating shaft is slower for clayish soil than for sandy soil.

Abstract: In a double-tube type boring and kneading machine comprising a double tubular shaft assembly composed of both an outer tubular shaft and an inner shaft separately rotatable to each other, said outer tubular shaft is adapted to be rotated at a high speed and provided at its external surface with a stirring and kneading means, and said inner shaft is adapted to be rotated with a large torque and provided with a boring bit at its leading end, a lower stirring and kneading means and a liquid discharge port. A method for improving a foundation ground by employing a double-tube type boring and kneading machine is also disclosed herein.

Abstract: A steel sheet pile for forming the wall of an excavation and the sheet pile assembly are disclosed herein. The steel sheet piles are in use to be arranged in side edge to side edge relationship with each other for supporting the wall of the excavation. Each sheet pile has a generally H-shaped cross section comprising a web with a wide flange on one side thereof and a narrow flange on the opposite side. Formed at the side edges of the wide flange are joint elements which interconnect the adjacent pairs of sheet piles. With this configuration of the sheet pile having the wide and narrow flanges, the sheet piles can be successfully placed along a curved wall or can form a corner portion thereof without the interference between the narrow flanges of the adjacent sheet piles. Accordingly, the sheet piles can be arranged to form not only a straight wall but also curved and corner walls of the excavation, under retention of high rigidity arising from the employment of the generally H-shaped configuration.