JPH051849B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] Industrial Application Field The present invention is directed to the driving of drainage reinforcing piles in the sandy ground surrounding a structure that prevents tensile failure of sandy ground and has a drainage function. It is about the method.

Conventional technology Conventional methods for improving sandy ground include sand compaction method, gravel compaction method,
The vibroflotation method, deep mixing method, and sheet pile method were included.

Problems to be Solved by the Invention However, the above-mentioned gravel compaction method is only expected to have a drainage effect, and the sand compaction method and vibroflotation method only have the effect of compacting sandy ground. Moreover, it was only possible to perform pouring in the vertical direction.

Furthermore, the deep mixing method is simply a method of hardening the ground with an improving agent such as cement, and if used on sandy ground, it will cause poor performance, and in the event of an earthquake, the load will concentrate on the poorly formed areas and cause destruction. Moreover, the sheet pile method was only a method of temporary tightening. Furthermore, with the exception of the sheet pile method, only new ground can be improved.
When sandy ground liquefies due to an earthquake and tensile force acts on the ground, causing the ground to break, there are problems in that gravel piles and sand piles have no ability to resist the tensile force.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to effectively prevent tensile failure of the ground caused by liquefaction of sandy ground during an earthquake, and to Sand around structures that can not only prevent subsidence but also effectively deal with existing structures such as underground structures such as tank foundation structures and underground structures, or semi-underground structures. The object of the present invention is to provide a method for driving drainage reinforcement piles in rough ground.

[Structure of the Invention] Means for Solving the Problems The method of driving drainage reinforcing piles in sandy ground surrounding a structure according to the present invention is a method for driving drainage reinforcing piles in sandy ground surrounding a structure. A hole is drilled diagonally in the ground in a risky area by rotating an auger inside a cylindrical casing, and when the specified depth is reached, the auger is pulled out with the casing intact. This method is characterized by inserting tensile materials such as rods and cage reinforcing bars into the casing, and pulling out the casing while adding crushed stone or porous concrete.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates sandy ground in which buried objects 2 such as box-shaped buried pipes and semi-underground structures 3 such as dug roads are constructed.

In the liquefaction risk area A of the ground surrounding these buried objects 2 and semi-underground structures 3, small-diameter drainage reinforcement piles 4 are installed.
are placed vertically or at an angle.

The upper end of the drainage reinforcing pile 4 is exposed on the ground surface and connected to the water collection mass 5. Therefore, the interstitial water absorbed by the drainage reinforcing pile 4 and rising up is collected in the water collection mass 5 and drained. Incidentally, the upper end portion of the reinforcing pile 4 is fixed to the ground surface by means of ground fixing means using foot protection concrete.

For example, as shown in Fig. 2, the drainage reinforcing pile 4 is constructed by installing a deformed PC rod 4a with an inner diameter of 100 mm and a node diameter of about 150 mm in a long hole drilled in the ground 1, and surrounding it by about 25 mm. The following crushed stone 4b is densely packed to have a pile diameter of approximately 250 mm.

Therefore, the crushed stones 4b are anchored to the surrounding sandy ground 1 and are also anchored to the irregularly shaped PC rods 4a, so that, for example, when a tensile force is applied to the ground 1, this tensile force is transmitted through the crushed stones 4b. The tension is transmitted to the irregularly shaped PC rod 4a, and the irregularly shaped PC rod 4a resists the tensile force of the ground 1.

Further, the compressive force of the ground 1 is resisted by the irregularly shaped PC rods 4a and the crushed stones 4b.

Furthermore, since there are gaps between the crushed stones 4b, the pore water in the surrounding ground 1 is absorbed into the gaps, rises, and is collected in the water collection mass 5 on the ground surface.

Furthermore, since the reinforcing piles 4 of this structural example are driven in an inclined state with respect to the ground surface, even if vibration occurs in either the vertical direction or the horizontal direction during an earthquake, the Compressive force and tensile force in the horizontal or vertical direction act on the reinforcing pile 4 as compressive force and tensile force in the direction of the inclined axis of the reinforcing pile 4, and are subjected to the resistance force of the reinforcing pile 4.

Fig. 3 shows another structural example of the drainage reinforcing pile 4, in which a gauntlet reinforcing bar 4c consisting of hoop bars with an outer diameter of about 150 mm and main bars connecting these hoop bars is erected using reinforcing bars with a diameter of about 13 mm. This is filled with crushed stone 4b of about 25 mm or less to create a pile diameter of about 200 to 250 mm.

The reinforcing pile 4 of this structural example also has the tensile resistance of the ground 1 and a drainage function, similarly to the reinforcing pile of the above structural example.

Fig. 4 shows that reinforcing bars 4b of, for example, 35 to 52 mmφ are placed in long holes of small diameter drilled in sandy ground 1, and porous concrete 4e is placed.
The pile diameter is approximately 150mm to 200mmφ.

Figures 5A to 5E show an embodiment of the reinforcing pile driving method of the present invention. First, as shown in Figure 5A, an auger 6b is rotatably placed in a cylindrical casing 6a. The inserted hole-drilling device is used to drill the hole while excavating and discharging earth and sand, and when a predetermined depth is reached, the auger 6b is pulled out with the casing 6a penetrating as it is, as shown in FIG. 5B.
Subsequently, as shown in Fig. 5C, the irregularly shaped PC rod 4a
A tensile material such as the like is inserted into the casing 6a, and crushed stone 4b is thrown in as shown in FIG. 5D. In this case, when the irregularly shaped PC rod 4a is thrown in while being vibrated with a vibrator, the crushed stones 4b are densely packed. Finally, as shown in FIG. 5E, the casing 6a is pulled out while vibrating to complete the construction.

In addition, when driving the reinforcing pile 4 shown in FIG.
is inserted and filled with crushed stone 4b.

Furthermore, when driving the reinforcing pile 4 shown in FIG. 4, reinforcing bars 4b are inserted in place of the irregularly shaped PC rods 4a, and porous concrete 4e is driven.

As described above, the drainage reinforcing pile may basically be any pile that has a large slenderness ratio, does not have a very high bending rigidity, and has a drainage function that resists tension.

[Effects of the Invention] 1. Since the drainage reinforcing pile is driven diagonally into the sandy ground, it can be easily constructed especially into the ground where an existing underground or semi-underground structure is constructed.

2. Since it is installed diagonally in the sandy ground in the liquefaction risk area around underground or semi-underground structures,
Excess pore water in the ground surrounding the structure can be quickly drained.

3. In addition to the drainage function, it can increase the tensile strength of the ground, preventing residual settlement of structures and restraining the deformation of sandy ground due to liquefaction during earthquakes.

[Brief explanation of the drawing]

Figure 1 is a diagram showing examples of construction of drainage reinforcement piles in the ground of underground structures and semi-underground structures, Figures 2 to 4 are diagrams showing various configuration examples of drainage reinforcement piles, and Figures 5A to 5E. The figure is a diagram showing the pouring method of the present invention. 1...Sandy ground, 2...Buried object, 3...Semi-underground structure, 4...Drainage reinforcement pile, 4a...Unusual PC rod,
4b...crushed stone, 4c...basket reinforcing bar, 4d...reinforcing bar,
4e...Porous concrete, 5...Water collection mass, 6a...Casing, 6b...Auger.

Claims (1)

[Claims] 1 Drill a hole diagonally in the ground in a liquefaction-prone area around an underground or semi-underground structure built in sandy ground while rotating an auger inside a cylindrical casing, and remove the casing when the specified depth is reached. The auger is pulled out while the auger is penetrated as it is, then tensile materials such as reinforcing bars, irregularly shaped PC bars, and cage reinforcing bars are inserted into the casing, and the casing is pulled out while putting in crushed stone or porous concrete. Method for driving drainage reinforcement piles in sandy ground around structures.