JPS61204417A - Method of forming pile increased in support force at pile tip by bagform substance - Google Patents

Abstract

PURPOSE:To increase a support force, by a method wherein a precast hollow pile with open ends is sunk for installation, and after a pouring pipe provided at its tip with a bagform substance, is inserted through the head to the tip of the pile, a foot protection material is poured into the bagform substance for expansion. CONSTITUTION:A precast holloe pile 1 with ends being open is sunk in an excavated hole for installation. A pouring pipe 5, provided at its tip with a bagform substance 3, is inserted through the hollow part of the pile 1 to the tip part of the pile 1. A curable foot protection material is poured for expansion to form a foot protection bulb 9 at the tip part of the pile 1.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for constructing ready-made piles, and more specifically, to a method for constructing piles that uses a bag-like material to increase the support force at the tip of the pile. It is.

(Prior art) Conventionally, the method of burying prefabricated piles has been the hammering method using a diesel hammer, but in recent years, due to noise and vibration regulations, hammering is no longer possible if there are private houses nearby. Alternatively, there is a method in which a ready-made pile is buried using a hollow digging method, and a bulb is created at the tip of the pile using an auger or high-pressure injection of cement milk to create a supporting pile.
Alternatively, a construction method is used in which the ground is excavated with an auger without soil removal, and a hardening bulb is created by expanding the excavation at the tip.

<Problems to be Solved by the Invention> However, these construction methods have the following problems. In other words, in each of these construction methods, the creation of the root hardening bulb at the tip of the pile involves stirring and mixing underground the supporting ground saturated with ground water and the root hardening material. The W/C (water-cement ratio) of the root solidifying material increases.

■There is a possibility that soil clod force may be mixed into the hardened bulb, and the composition of the bulb will not be uniform.

■The root hardening material flows into the hollow part of the stake, and the amount of root hardening material injected =
The volume of the bulb is not determined, and the size of the bulb cannot be controlled from the amount of injection.

■There is a fall of the stake into the hardened bulb.

Particularly in cases (1) and (2), the problem arises that the strength of the hardened bulbs decreases, that is, the supporting capacity of the pile decreases.

<Means for Solving the Problems> The present invention provides a method for solving the problems of the conventional method as described above. Insert the injection tube to which the bag-like object is attached through the hollow part of the ready-made hollow pile to a predetermined position at the tip of the ready-made hollow pile, and then inject a cement into the bag-like object from the tip of the injection tube to inflate it. This problem was solved by using a pile construction method that increases the bearing capacity of the pile tip using a bag-like material made by creating a root hardening bulb at the tip of the pile.

(Example) The configuration will be explained below based on an embodiment shown in the drawings.

FIG. 1 is a construction procedure explanatory diagram showing an example of the construction method of the present invention. After drilling to the specified depth for pile sinking using a soilless auger, the auger is rotated in the opposite direction and the tip bit is enlarged to enlarge and excavate the bulbous part to the required diameter and depth. At this time, as the drilling fluid, water alone may be used, or cement milk may be used to solidify the integration of the root hardening bulb covered with the bag-like material and the supporting ground. This enlarged excavation range is (diameter: 1 of the pile diameter) in order to ensure sufficient support for the pile.
It is desirable that the size is approximately 2 times) x (height: 1 to 5 times the pile diameter).

After the excavation is completed, the auger is pulled out and a ready-made hollow pile with both ends open is sunk to a predetermined depth. After that, an injection tube with a bag-like material of a predetermined length attached to the tip is inserted through the hollow part of the stake into the designated position at the tip of the stake, and then a hardening agent is injected with pressure to create a hardening bulb. do. The bag-shaped material 11c used at this time is typically made of woven or non-woven fabric made of synthetic fibers such as high-strength nylon, polyester, vinylon, polyamide, acrylic, etc., but other materials include metal foil and synthetic resin. Conceivable. Considering price, flexibility, pressure resistance, etc., I think that fabrics using synthetic fibers are better.

Moreover, as the hardening material, water glass, cement milk, cement mortar, and other materials conventionally used as root hardening materials can be considered.

Especially in the combination of fabric + cement mortar,
By injecting mortar into the bag under pressure, water in the mortar is dehydrated and a high-strength mortar is obtained.

To create a bulb, start pouring from the lower end of the bulb that has been excavated in advance, and then inject while pulling up the injection pipe in order to push up the excavated soil in the root hardening area and discharge it through the hollow part of the pile, forming a bag-like material. You will get surrounded, high quality root hardening bulbs.

By making the upper end of the bag shaped as shown in FIG. 3 and having the same diameter as the inside diameter of the stake, the stake and the hardened bulb can be well integrated.

To attach the bag to the injection pipe, for example, as shown in FIG. 4, a plate with a screw is placed on the top of the bag, and the bag is attached to the injection pipe using the threaded portion.

In this case, after the hardening bulb has been created, the injection tube will be rotated to separate it from the bag-like material, and the injection tube will be pulled up.

Of course, the injection tube may be attached by covering the injection tube with a bag-like material.

<Effects of the Invention> By creating hardened bulbs by the above method, the following improved effects can be obtained compared to the conventional method.

(2) Since a root hardening material with a formulation capable of developing a predetermined strength is injected into the bag, there is no increase in the W/C of the root hardening material, and bulbs with a uniform composition can be obtained.

■By applying pressure and injecting the hardening material into the bag, it can be fully integrated with the original ground.

Since the root solidifying material is injected into the bag-like material, the amount of injection can be controlled. In other words, injection amount - bulb volume.

■The tip of the stake has a strong bulb whose outer periphery is covered with a bag-like substance, so the stake does not fall.

However, compared to various conventionally used methods, better root hardening bulbs can be obtained and the pile tip supporting force can be improved.

[Brief explanation of drawings]

FIG. 1 is a construction procedure explanatory diagram of an example of the construction method of the present invention. Figure 2 is a perspective view of the stake and hardening bulb. FIG. 3 is an example of the shape of a bag-like object. FIG. 4 is an example of the connection between the injection tube and the bag-like object. 1, <i, 2. Tip hardened bulb, 30 bags, 4. Board 5,
injection tube, 6. screw, 7. Auger, 8. Root hardening material 9, enlarged and excavated bulb part 10, portion having the same diameter as the inner diameter Patent applicant: Asahi Kasei Corporation Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] After sinking a ready-made hollow pile with both ends open to a predetermined depth, an injection tube with a bag-like material attached to the tip is inserted through the hollow part of the ready-made hollow pile to a predetermined position at the tip of the ready-made hollow pile, and then the bag is inserted from the tip of the injection tube. A pile construction method for increasing the bearing capacity of pile tips using a bag-like material, which involves injecting root-hardening material into the pile and expanding it to create a root-hardening bulb at the tip of the pile.