JP2794324B2 - Underground pile driving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a mid-digging pile driving method that can be constructed while preventing damage to piles.

<Prior Art> There is known a middle digging type pile method in which a pile can be constructed without noise and without vibration by excavating a hollow portion of an existing pile and inserting the pile by its own weight or press-fitting.

In this method, since the pile tip is placed on the support layer, the supporting force is small.

Therefore, as a countermeasure, a method of hitting the pile head and penetrating the tip of the pile into the support layer by about 1 m to increase the supporting force is taken.

<Problems to be Solved by the Present Invention> In the above-mentioned conventional medium digging type pile driving technique, it is not possible to confirm the deformation of the pile tip while the pile is being set.

 For this reason, the pile tip is driven until it is broken.

<Object of the present invention> The present invention has been made in order to solve the above-mentioned problems. To provide.

<Means for Solving the Problems> That is, the present invention relates to a middle-digging type pile driving method in which a pre-existing pile is press-fitted while excavating forward from a pile tip by using an excavating apparatus housed inside a pre-existing pile. A plurality of distance measuring sensors are attached to the pile, a distance between an outer peripheral surface of the excavator and an inner peripheral surface of the existing pile is measured by the distance measuring sensor, and a deformation of a tip of the pile is obtained from a change in the distance.

<Description of the Present Invention> Hereinafter, the present invention will be described with reference to the drawings.

<B> Pre-built piles Fig. 1 shows an example of construction using the mid-digging pile driving method.

Reference numeral 1 denotes a hollow prefabricated pile having both ends opened, and a concrete pile, a steel pipe, or the like can be used.

<B> Drilling means 2 is a drilling device for drilling prior to the tip of the existing pile 1.

The drilling device 2 is a rotary drilling type device having a bit 3 on the lower surface of a cylindrical body, but other known drilling devices can be used.

The excavator 2 has a sludge pipe 4 having a function of transmitting torque.
Is connected.

The excavated soil is discharged to the outside of the hole through a drain pipe together with the muddy water 5 filled in the existing pile 1.

Reference numeral 6 denotes a stabilizer for securing the center of the excavator 2, which is attached in the middle of the exhaust pipe 4.

<C> Deformation detection means In the present invention, a plurality of distance measuring sensors 7 are attached to the peripheral surface of the excavator 2 and the distance between the excavator 2 and the peripheral surface of the existing pile 1 is measured to detect the deformation of the existing pile 1. Monitor.

As the distance measuring sensor 7, a known sensor that can transmit an ultrasonic wave and measure a distance based on the reflected sound can be used.

<Operation> Next, the construction method will be described.

<A> Excavation / Sinking While excavating the tip of the existing pile 1, the existing pile 1 is pressed into the ground using its own weight or a press-in device or a hitting device, as in the related art.

Note that the excavation by the excavator 2 and the press-fitting of the existing pile 1 must be performed at substantially the same speed.

<B> Grasp of deformation In parallel with the excavation work by the excavator 2, the distance C between the outer periphery of the excavator 2 and the inner periphery of the existing pile 1 is measured by a plurality of distance measuring sensors 7 arranged in the excavator 2. Perform measurement work.

If the stress is concentrated on the tip of the preformed pile 1 and is greatly deformed or broken, the distance C at that point is measured by changing the distance C as compared with the others.

Thereby, the work of setting the existing pile 1 is performed while grasping the deformation occurring in the existing pile 1.

When the damage of the existing pile 1 is predicted from the data of the interval C, the pressure is reduced or the best measures are taken to settle the pile.

<Effects of the Present Invention> The present invention has the following effects.

<B> The deformation state of the tip of the pile can be grasped in parallel with the work of setting the existing pile.

Therefore, it is possible to prevent a breakage accident at the tip of the pile as before.

<B> Since the condition of the pier can be instantly known, the best countermeasures are taken.

<C> Since the change of the inner peripheral surface of the existing pile is measured, the measurement is not affected by collapse of the hole wall.

[Brief description of the drawings]

 Fig. 1: Cross-sectional view showing an example of construction Fig. 2: Cross-sectional view of II-II in Fig. 1

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) E02D 7/00 E02D 13/06

Claims (1)

(57) [Claims] In a mid-digging pile driving method for press-fitting a preformed pile while excavating ahead of a pile tip with a drilling device housed inside a preformed pile, a plurality of distance measuring sensors are attached to the outer periphery of the excavation device. A middle-digging pile driving method, wherein a distance between an outer peripheral surface of an excavator and an inner peripheral surface of an existing pile is measured by the distance measuring sensor, and a deformation of a pile tip is obtained from a change in the distance.