JPS626023A - Construction work for foundation pile - Google Patents

Abstract

PURPOSE:To support a foundation pile vertically and concentrically with the center line of an excavated pit by a method in which the foundation pile is penetrated almost concentrically with a casing into the excavated pit, the aperture between the foundation pile and the casing is filled with a sandy filler, and the casing is raised to the outside of the pit. CONSTITUTION:An auger 2 is discharged to the outside of a pit, the inner wall of the excavated pit 3 is supported by a casing 1, and a concrete pile 4 is penetrated into the casing 1. Sandy filler 5 is then charged into the casing 1 from an opening 13 in such a way that the center line of the pile 4 coincides with the center line of the casing 1. When the casing 1 is slowly pulled up, the aperture(t) is filled with the sandy filler 5, and the inner wall of the pit 3 is held through the filler 5 by the periphery of the pile 4. The verticality of the foundation pile in the pit 3 can thus be raised, and the bearing force of the foundation pile can be enhanced without degradation of the underground soil.

Description

[Detailed description of the invention] "Industrial application field" The present invention relates to a method for constructing foundation piles for structures, etc.

"Prior Art" Conventionally, a foundation pile is inserted into an auger hole, and the gap between the foundation pile and the auger hole is filled with a liquid filler such as bentonite solution or cement milk.

In addition, the auger hole is generally bent slightly more than the screw joint, making it difficult to maintain verticality.In particular, when it comes into contact with underground basalt boulders (compressive strength 1700-1800 fcrl in Hirado, Nagasaki Prefecture), the auger's resistance causes it to bend. It is difficult to drill vertical holes because of the bending. For this purpose, the casing was rotated to keep it vertical and the foundation hole was excavated using an internal auger.

However, when a foundation pile such as a concrete pile is inserted into a foundation hole, the pile tends to tilt inside the hole due to the gap between the pile and the foundation hole.
In addition, if the casing is removed, the above-mentioned gap causes poor soil adhesion to the pile, and if the casing adheres closely, the soil is likely to be damaged and the bearing capacity to be reduced. The liquid filler in the gap could not maintain the verticality of the pile, and the bearing capacity was inevitably reduced due to damage to the soil.

"Problems to be Solved by the Invention" The present invention secures the verticality of the foundation hole, ensures the verticality of the foundation pile inserted into the hole, prevents damage to the soil, and increases the bearing capacity of the pile. 0 ``Means for Solving the Problems'' The present invention involves lowering a casing and drilling a bore hole with an auger inside the casing, and then lifting the auger out of the hole along the casing. , after that, a foundation pile is inserted into the excavated hole almost concentrically with the casing, and the gap between the foundation pile and the casing is filled with a sand-like filler, and then the casing is raised out of the hole. It is constructed using the pile construction method.

``Function'' Therefore, when an underground boulder is touched during excavation, the cutter at the lower end of the casing or high-pressure jet water cuts the boulder, protects the rotation of the internal auger, and maintains the verticality of the excavation. Furthermore, after the auger is raised, the inner wall of the wellbore is held by the residual casing, preventing the inner wall from collapsing. Then, the foundation pile inserted into this casing is held concentrically with the center line of the casing, and in this state, sand-like filler is filled into the gap from the upper end opening of the casing to the vicinity of the upper end of the casing (above the ground). When the casing is slowly removed out of the hole using a crane, etc., the above-mentioned filler material enters and fills the voids in the thick part of the casing, filling the voids in the thick part of the casing, and the foundation pile is aligned with the center line of the excavated hole. The hole wall, which is held substantially concentrically and vertically after the casing has been removed, is held by the sand-like filler. .

``Example'' An auger 2 is fitted into the inside of a rotating casing 1 having a cutter 6 provided at the lower end, and the auger 2 is rotated in opposite directions to be propelled into the ground to drill an excavation hole 3. The basalt boulders 7 in the ground are cut by the cutter 6 of the rotating casing 1. After reaching the specified depth, stop descending and the auger 2
The rotation of the auger 2 discharges the excavated earth and sand out of the hole, and by stopping the rotation and discharging the auger 2 out of the hole, the inner wall of the borehole 3 is held by the casing 1 (Figure i).
. In this state, a concrete pile (foundation pile) 4 with gap support protrusions 9 protruding from the lower end steel plate 8 on three sides is inserted into the casing 1, and the upper end of the pile 4 has a conical shape -l.
By aligning the lower end protrusion of O, gap support protrusions 11 are provided on the outer periphery of the open lid lO to protrude in three directions, and the center line of the pile 4 is aligned with the center line of the casing L (Fig. 3). 11 may be provided on the upper end steel plate 8 of the pile 4. The upper end of the casing l projects above the ground 12 and has an opening 13. In this state, when the sandy filler 5 (hereinafter referred to as sand) is introduced into the casing 1 through the opening 13, the sand descends through the 5 spaces @t and fills the gap t from the lower end (Fig. 4). The input amount of 5 is approximately io~30% larger than the total volume of the thick portion of the casing 1 and the volume of the gap, and is stored in the upper part of the lid 10. In this state, when the casing 1 is slowly pulled upward by a crane or the like, the sand 5 fills the gap t created in the thickness of the casing 1, and the inner wall of the excavated hole 3 finally becomes a pile 4 as shown in FIG. It is held on the outer surface of the body through sand 5. In addition, what is indicated by 14 in the figure is Fi+-Singl.
This is a vibrator for lifting the casing installed at the upper end of the casing.

"Effects" Since the present invention is based on the method described above, it is possible not only to improve the verticality of the excavated hole 3 for the foundation pile, but also to improve the verticality inside the excavated hole 3 of the foundation pile 4. This has the effect that the soil quality is retained on the outer surface of the foundation pile 4 via the sandy filler 5 without collapsing, and the supporting capacity of the foundation pile 4 can be improved.

[Brief explanation of the drawing]

Figure 1 is a front view of the excavated hole in the foundation pile construction method of the present invention, Figure 2 is a front view of the buried casing, Figure 3 is a front view of the foundation pile inserted, and Figure 4 is a sand Fig. 5 is a plan view taken along the line A-A in Fig. 4, Fig. 6 is a drawing of the casing being pulled up, Fig. 7 is a drawing of the casing being pulled up, and Fig. 8 is a drawing of the completed construction. It is a diagram. l...Casing, 2...Auger, 3...Drilling hole, 4
...Foundation pile, T...Gap, 5...Sandy filler.

Claims (1)

[Claims] (1) After lowering the casing and drilling an excavation hole with the auger inside the casing, the auger is raised out of the hole along the casing, and then a foundation pile is inserted into the excavation hole almost concentrically with the casing. , a foundation pile construction method characterized by further filling the gap between the foundation pile and the casing with a sand-like filler and then lifting the casing out of the hole.