JPH01214686A - Pilot boring method - Google Patents

Abstract

PURPOSE:To remarkably reduce extra troubles and prevent damage to buried pipeline, etc., by cutting the ground while injecting high pressure water from the head of a drilling rod, and simultaneously inserting a casing tube. CONSTITUTION:High pressure water is injected and spreaded out from a nozzle part 1a provided on the head of a drilling rod 1 to form a a drilling hole of larger diameter than the rod 1, and a casing tube is inserted into the drilling hole. Thus, a possibility of damage to buried pipeline, etc., is eliminated, an extra trouble such as an exploratory drilling can be saved, and the formation of drilling hole can be performed simultaneously with the insertion of the casing tube.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a preliminary boring method.

Conventional technology and its problems In ground improvement methods that use double or triple pipes to inject chemicals, boring and casing tubes must be installed prior to installing the double pipes. . When performing advance boring like this in a place with many buried pipes,
In order to prevent accidents involving damage to buried pipes, it was necessary to conduct trial excavations, which was extremely troublesome. Furthermore, in the past, boring and casing tube erection were performed in separate processes, which required time and effort.

The present invention has been made with the aim of eliminating such conventional problems.

Means for Solving the Problems The present invention aims to form a hole in the ground with a diameter larger than that of the rod using high-pressure water that is injected from the lower end nozzle portion of a hollow rod for drilling in a shape that widens toward the end. This relates to a preliminary boring method characterized by inserting a casing tube into the borehole.

EXAMPLE An example of the construction method of the present invention will be described below based on the accompanying drawings.

From the implementation situation of the construction method of the present invention shown in FIG.

As is clear, when forming the preliminary boring, a hollow drilling rod (1a) having a nozzle part (1a) at the lower end is used.
) and a casing tube (2) having a larger diameter than the rod (1). 2nd class rod (1) and tube (
2) At the upper end after the concentric combination state,
It is configured such that it is individually gripped by a chuck part (not shown) of a construction machine (not shown), and simultaneously lowered downward from this gripping position as drilling progresses.

As shown in FIGS. 2 and 3, the rod (1)
The lower end nozzle part (1a) has a central nozzle hole (1a+) and a large number of side nozzles, for example eight, which are opened obliquely outward at equal intervals on a circular locus centered on the nozzle hole (1a+). Hole (la2)・
··have. The inclination angle θ(
(see FIG. 2) is appropriately selected within the range of 5 to 30 degrees.

As shown by the arrow mark (3) in Fig. 1, when high pressure water is supplied into the inside of the rod (1) from the upper end, the high pressure water flows through the nozzle holes (1al) (1a2) of the lower end nozzle part (1a).
It is injected from ... and forms a hole (b) in the ground (a). At this time, the high-pressure water is injected obliquely outward from the nozzle hole (1a2), that is, in a shape that spreads toward the end, so that the lower end of the nozzle part (1a) and the drilled hole (b) By maintaining a predetermined distance (C) between the rod and the bottom of the rod, it is possible to form a hole (b) having a diameter larger than that of the rod (1) and into which the casing tube (2) can be built.

As shown in FIG. 1, while continuing to spray high-pressure water from the lower nozzle part (1a) of the drilling rod (1), the nozzle part (1a) and the hole drilling (b) By inserting and lowering the rod (1) and casing tube (2) into the drilled hole (b) while maintaining a predetermined distance (C) between them and the bottom of the hole, the rod (1) and the casing tube (2) are protected by the casing tube (2). It is possible to form a drilled hole (b). The rod (1) and tube (2) may be inserted and lowered into the drilled hole (b) either under rotation or non-rotation.

The muddy water produced by the formation of the drilled hole (b) is discharged to the ground through the gap (4) formed between the rod (1) and the casing tube (2). In order to facilitate the discharge of this muddy water, a casing tube (2
), the discharge ports (2a) can be formed in advance in multiple stages in the upper and lower directions.

In this way, the muddy water rising in the gap (4) is discharged from the outlet (2a) at the lowest position on the ground, and the water head of the muddy water can be kept low. In addition, in the preliminary boring operation, the lower end of the casing tube (2) is terminated at a position that does not interfere with the injection of high-pressure water from the injection holes (1a+) (la2) of the lower end nozzle part (1a). . Moreover, the material of the tube (2) may be made of synthetic resin such as hard vinyl chloride resin or base steel.

Effects According to the method of the present invention, preliminary boring is performed using high-pressure jet water to guide the hole, so even if the pipe collides with a buried pipe during boring, there is no risk of damage, and troublesome test drilling etc. In addition to eliminating the need for preliminary work, the drilling process and casing tube installation can be performed simultaneously, which reduces the number of man-hours to just one step, which significantly reduces the number of steps required for preliminary boring. .

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing the implementation status of the construction method of the present invention, Figure 2
The figure is an enlarged sectional view of the lower end nozzle part, FIG. 3 is a plan view thereof, and FIG. 4 is a partially cutaway side view showing an example of the casing tube. In the figure, (1) is a drilling rod, (2) is a casing tube, and (3) is an arrow mark (4) which is a circumferential gap. (That's all) Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] (1) High-pressure water is sprayed from the nozzle at the lower end of the hollow rod for drilling in a widening shape to form a hole in the ground with a diameter larger than that of the rod, and the casing tube is inserted into the hole. This advance boring method is characterized by: