JPH09203727A - On-the-ground inspecting method for soundness of bearing pile, etc., driven into the ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a method to inspect whether a bearing pile, etc., constructed underground is in the sound condition, from over the ground surface while the positioning remains in the initial. SOLUTION: At least two metal members 3 for inspection are installed in such a way as elevating to over the ground surface from the head of a pile concerned, and after curing of the pile, a sensor 5 of an inspection system 4 is installed on the top of one of the metal members 3 protruding over the ground surface, while the top of the other metal member 3 is excited, and the vibratory propagation in the pile 1 and the situation of reflected waves are recorded and displayed by the inspection system 4. The obtained vibratory propagation and the situation of reflected waves are observed, and inspection and/or check is made if there is any damage in the pile 1 and the position if any.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention inspects whether or not a support pile, etc., which is constructed underground, is in a healthy state in the foundation work of construction / civil engineering from the ground surface at the original position immediately after the construction of the pile. On how to do.

[0002]

2. Description of the Related Art It is necessary to inspect and check in-situ whether or not a support pile or a friction pile that has been constructed to a depth that reaches the support layer from the ground has been constructed in a healthy state. It is extremely important as well as inspecting and confirming the safety of the buildings etc. For example, when constructing piles with ready-made concrete piles, cracks (such as cracks that require reinforcement, or those that are invisible to human eyes) during transportation, lifting, or construction of ready-made concrete piles are required. Hair cracks are likely to occur. Even in the case of cast-in-place concrete piles, there is a great need for quality control after construction. However, it is not easy to inspect and confirm the soundness in-situ over the entire length of a pile that is actually deeply buried in the ground by non-destructive testing.

In the conventional inspection method, the head of a pile constructed in the ground is hit with a hitting body, and the vibration in the pile due to the hitting is detected by a vibration detector of the head, and the detected vibration waveform It is the content to be inspected based on.

[0004]

The above-mentioned conventional inspection method can be considered effective at first glance, but the position of the pile heads such as support piles is at the lower end of the building foundation or the first to third basements. Since it is at a depth to support the bottom of the foundation located at the depth, the known inspection method is based on the premise that the pile head is exposed on the ground surface, and the pile head exposed by cutting the ground is exposed. It is a method to inspect. Therefore, the serious drawback of this inspection method is that if a large crack is detected as a result of the inspection if reinforcement or reinforcement of the pile is required, it will be lost soon, and subsequent countermeasure construction is very difficult. Even if countermeasures are taken, economic loss is large. This is because the additional driving of the pile is performed at a position adjacent to the support pile, and in order to perform the additional driving, there is no choice but to call back the pile driver etc. that was once returned and construct it, and the usage fee of the mechanical equipment increases. However, since there is no other way than to put down a pile driver etc. to the root cutting bottom, it is difficult to prepare, and in the end, the loss per day reaches several million yen. In other words, after the pile construction, if the pile inspection results are promptly obtained while the pile driver etc. are still present, it is convenient to take countermeasure construction such as additional striking immediately.

Therefore, an object of the present invention is to inspect the soundness of a support pile or the like which is constructed from the ground surface to the ground immediately after a considerable curing period has elapsed after the construction of the pile, that is, immediately before root cutting. It is to provide a possible method.

[0006]

As a means for solving the above-mentioned problems, the invention of claim 1 is a method for inspecting and confirming the soundness of constructed support piles from the ground surface,
At least two inspection metal members that stand up from the pile head of the pile to the ground should be installed, and after curing the pile, attach the sensor of the inspection system to the upper end of the one metal member protruding above the ground. , Vibrating the upper end of the other metal member to record and display the state of vibration propagation and reflected wave in the pile by the inspection system, recording, and propagation of the displayed vibration in the pile Also, it is characterized by observing the situation of reflected waves and inspecting and confirming the presence or absence of damage in the pile body and the position of damage.

According to the invention of claim 2, when the pile of claim 1 is constructed by a prefabricated concrete pile, a plug suitable for a bolt hole provided in advance in the fitting metal fitting of the pile head is prepared, and the bolt is prepared. It is characterized in that a plug is attached to the hole and a lower end of a metal member having a length reaching the ground is joined to the plug so that the metal member rises from a pile head in the ground to the ground.

According to the invention of claim 3, when the pile of claim 1 is constructed as a cast-in-place concrete pile, the reinforcing ring on the upper portion of the pile reinforcing bar cage has at least a length to cut the edge with the cast concrete. A vertical separation pipe is provided vertically with the tip closed to the extent that concrete does not enter, and a metal member with a length that reaches the ground is inserted into the separation pipe, and the lower end of the separation pipe is piled together with a reinforcing cage. Built in,
The metal member is characterized in that the inside of the pile hole is raised to the ground and then concrete is poured.

According to a fourth aspect of the present invention, when the pile of the first aspect is constructed as a cast-in-place concrete pile, the pile reinforcing bar cage is built into the pile hole, and after the concrete is placed, the concrete is Before hardening, a separation pipe having a length to cut at least the edge of the cast concrete and having a tip closed to the extent that concrete does not enter and a metal member inserted into the separation pipe are both in the concrete of the pile head. It is characterized in that it is inserted into and the metal member rises from the pile head to the ground.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The inventions of claims 1 to 4 are preferably carried out when the pile body is constructed with ready-made concrete piles or cast-in-place concrete piles. The diameter of piles ranges from 30 cm to 300 cm for large holes. The longer the length of the pile, the higher the accuracy of the inspection, but the range from support piles long enough to reach the underground support layer to friction piles that do not reach the support layer.

The vibration of the metal member is preferably carried out by hammering the metal member with a proper strength and at a predetermined time cycle. At least one metal member that vibrates and the vibration propagation state in the pile body (reflection waveform) with the vibration sensor
It is sufficient to have two in total, one for detecting, but if it is necessary to inspect several points in the plane shape of the pile with a large diameter in detail, prepare several more metal members in an appropriate arrangement. Then, it is preferable to inspect each of them. The metal member applied to the cast-in-place concrete pile cuts the edge to prevent it from adhering to the concrete to be placed (if it adheres, good elastic wave = P wave is difficult to generate unless a strong impact is given, and the inspection accuracy is high. Therefore, a separation pipe (steel pipe, vinyl chloride pipe, etc.) that cuts the edge with concrete is provided and the metal member is arranged in it.

[0012] When the pile body is constructed with ready-made concrete piles, a steel pipe having a hollow inner surface with a thread, a water pipe joint, or a stud bolt is preferably used.
A steel pipe, a steel rod, or the like is suitable for the metal member. The inspection system applied is a non-destructive soundness inspection device, more specifically an accelerometer inspection device. Attach a sensor to the upper end of one metal member protruding to the ground,
The other metal member is appropriately hit with a small hammer or the like to generate an elastic wave and propagate it into the pile body. The traveling state of the elastic wave in the pile body can be expressed by a general wave equation as long as the pile body can be regarded as a homogeneous body (elastic body), and vibration on a pulse with a short duration due to impact as a traveling wave of the pile body It reaches the tip and part of it is transmitted, but the rest is reflected and becomes a receding wave toward the pile head, which is detected by the sensor. Also,
If there is a cross-section defect due to a crack or the like in the middle of the pile body, a backward wave reflected at the position of the cross-section defect is generated and detected by the sensor as shown in FIG. Therefore, the aspect of the detected waveform, and
By superimposing and observing the time course, it is possible to confirm the presence or absence of cracks or the like that have occurred in the pile body and the position thereof.

The above-mentioned inspection system has a configuration in which the detected acceleration signal is subjected to an appropriate frequency filter, and the amplification factor of the acceleration signal by the amplifier is increased with time in order to cope with the attenuation of the wave propagating through the pile body. Has been done. The response vibration of the pile is recorded as a digital value in the inspection system and displayed on the display each time it is excited once. In order to confirm the reproducibility of the measured waveform and average the response vibrations, it is preferable to carry out several trial runs.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 1 shows an outline of the implementation of the inspection method of the present invention.
Two metal members 3, 3 that stand up from the pile head of the pile body 1 deeply formed in the ground to the ground through the pile hole 2.
Is installed. By the way, the depth of the pile head of pile body 1 is
In the case of a normal building, the first to third basements (GL-1.5
m to -15.0 m). In the case of cast-in-place concrete pile, an extra portion D of about 50 cm is further formed on the pile head. A vibration sensor (acceleration sensor) 5 of the inspection system 4 is attached to the upper end of the one metal member 3. The upper end of the other metal member 3 is struck by a hammer 6 to vibrate, and the elastic wave propagated through the pile 1 and its reflected wave (response vibration) are vibrated by the vibration sensor 5
Is detected by The response vibration (acceleration signal) detected by the vibration sensor 5 is processed by the inspection system 4 having the configuration shown in FIG. First, after eliminating noise with a frequency filter, amplification is performed with the amplifier 7, and the digital value converted by the A / D converter 8 is recorded in the memory 9,
It is displayed on the display 10, and further input to the personal computer 11 to perform various processing operations. By the processing operation of the personal computer 11, the propagation and vibration of vibrations recorded and displayed in the pile body as described above are observed, and the presence or absence of damage in the pile body, the position of damage, etc. are confirmed in detail.

3 to 5 show an embodiment of means for preparing a metal member on the pile head when the pile body 1 is constructed with ready-made concrete piles. At the final stage of constructing piles,
A tubular plug 14 having a male screw portion 13 that is screwed into the bolt hole is attached to a bolt hole for attaching a piano wire of a joint metal fitting 12 for joining the piles attached to the upper end portion of the pile (built-up pile). It is attached. The plug 14 is formed of a tube body having an outer diameter of 34 mm and a length of 100 mm, for example, and a female screw for joining is formed on the inner surface of the tube. When building the prefabricated pile at the final stage, the steel pipe 3 as a metal member is screwed and joined to the female screw of the plug 14 on the ground. The plug 14 may be in the form of a buried bolt, or may be threaded on the inner surface of a steel pipe that is a metal member, and the screw may be joined to the upper portion of the bolt that is the plug. The steel pipe 3 has a length protruding from the pile head to the ground. At least two steel pipes 3 are provided as described above.

Next, FIGS. 6 and 7 show an embodiment of means for preparing a metal member on the pile head when the pile body 1 is constructed by cast-in-place concrete. The means is to install the reinforcing rod cage 20 for piles in the hole 2 for piles by attaching it to the reinforcing cage beforehand on the ground and installing the reinforcing cage 20 at the same time when the cage 2 is installed, and in the hole 2 for piles. This is roughly classified into a case where the concrete is installed to the predetermined level after being installed and the concrete is inserted into the hole 2 for piles from the ground before the concrete is not yet hardened.

FIGS. 6 and 7 show the former embodiment, in which an annular reinforcing bar at the upper end of the reinforcing bar cage 20 (located inside the reinforcing bar cage and used for positioning the longitudinal main bars). A connecting material 22 is provided in the diameter direction of the reinforcing ring 21), and an inner diameter of 30 mm and a length of extra concrete are provided at two positions on the connecting material 22 that are appropriately separated. Depth (about 50 cm)
A separation pipe 23 of a length to be cut off without being buried in the cast concrete for a little longer than that is attached vertically upward by means such as welding. The opening at the lower end of the separation pipe 23 is previously closed with a mortar plug 24 or the like that can be crushed later to prevent concrete from entering. Before building the rebar cage 20 into the hole 2 for piles, the steel pipe 3 as a metal member formed in the cone portion 25 having a sharp tip is inserted into the separation pipe 23 on the ground.
After the reinforcing rod cage 20 is built and concrete is placed in the hole 2 for piles, when the concrete develops strength by curing for 3 days, the steel pipe 3 is strongly pushed down from the ground to crush the mortar plug 24. Then, the cone portion 25 at the tip of the steel pipe 3
After properly penetrating into the concrete skeleton, the inspection is started.

When the reinforcing bar cage 20 is built in the pile hole 2 in advance and the metal member is installed after the concrete is placed in the pile hole 2, the concrete is not yet hardened after the concrete is placed. Before, the two separating pipes 23 and the steel pipes 3 of the structure without the reinforcing ring 21 and the connecting material 22 of FIG.
6 is lowered from the ground into the hole 2 and is inserted and inserted until the separation pipe 23 reaches the position of the reinforcing ring 21 in FIG. 6 (the substantial pile head). Then, after about 3 days of curing the concrete, the steel pipe 3 is strongly pushed down to crush the mortar plug 24, and the cone portion 25 at the tip of the steel pipe 3 is appropriately penetrated into the concrete skeleton, and then the inspection is started. What to do is the same as the previous example.

[0019]

According to the inspection method of the present invention, after the support piles have been constructed and a considerable curing period has elapsed, before the root cutting work is started, more specifically, mechanical equipment such as a pile driver is installed. Since the soundness of the piles that have been constructed can be inspected in detail from the ground surface at the stage where they are still at the work site, if countermeasures such as overstrike of piles are required and the soundness is impaired, the existing mechanical equipment will be immediately used. Can be dealt with quickly and economically from the ground level.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of implementation of an inspection method of the present invention.

FIG. 2 is a configuration diagram of an inspection system.

FIG. 3 is a plan view of an already-built pile head.

FIG. 4 is a front view of a head portion of a prefabricated pile at the final stage.

FIG. 5 is a cross-sectional view of a structure in which a steel pipe is attached to a joint metal fitting.

FIG. 6 is a cross-sectional view showing a state where a steel pipe is attached to a rebar cage of a cast-in-place concrete pile.

FIG. 7 is a perspective view in which a steel pipe is attached to a reinforcing ring.

FIG. 8 is an explanatory diagram showing a state of a cross-section defect of a pile body and a reflected wave from the tip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pile body 3 Inspection metal member 4 Inspection system 12 Joint hardware 14 Plug 2 Pile hole 20 Rebar cage 21 Reinforcement ring 23 Separation pipe 24 Mortar stopper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Ono 1-4-15 Komazawa, Setagaya-ku, Tokyo Within Tokyo Soil Research Co., Ltd. (72) Takahiro Hayashi 3-24-2 Aoi, Higashi-ku, Nagoya, Aichi Prefecture Inside Yorkon Co., Ltd.

Claims (4)

[Claims] 1. A method for inspecting and confirming the soundness of a support pile or the like constructed in the ground from the ground surface, and at least two metal members for inspection rising from the pile head of the pile to the ground are prepared. After curing the pile, attach the sensor of the inspection system to the upper end of the one metal member protruding from the pile head to the ground,
By vibrating the upper end of the other metal member, recording and displaying the state of the propagation of the vibration and the reflected wave in the pile by the inspection system, the recording and the propagation of the vibration in the pile being displayed. The soundness of supporting piles etc. constructed from the ground surface to the ground is characterized by observing the condition of reflected waves and inspecting and confirming the presence or absence of damage in the pile body, the position of damage, etc. How to inspect. 2. When the pile according to claim 1 is constructed by a ready-made concrete pile, a plug is attached to the joint metal fitting of the pile head,
A support pile constructed from the ground surface to the ground, characterized in that the lower end of a metal member having a length reaching the ground is joined to the plug to raise the metal member from the pile head in the ground to the ground. How to check the health of. 3. When the pile according to claim 1 is constructed as a cast-in-place concrete pile, the reinforcing ring on the upper portion of the reinforcing bar basket for pile body has at least a length for cutting the edge with the cast concrete. A separation pipe whose tip is closed to the extent that concrete does not enter is installed vertically upward, and a metal member with a length that can reach the ground is inserted into the separation pipe and the lower end is built into a pile hole together with a rebar cage. The method for inspecting the soundness of a support pile or the like constructed from the ground surface to the ground, characterized in that the metal member raises the inside of the pile hole to the ground. 4. When the pile according to claim 1 is constructed as a cast-in-place concrete pile, at least before the concrete is hardened after the pile reinforcing bar cage is built in the excavation hole and the concrete is cast. A metal member which has a length to cut the edge with the cast concrete and has a tip closed to the extent that concrete does not enter and a metal member inserted into the pipe are inserted into the concrete of the pile head. Is characterized by rising from the pile head to the ground,
A method for inspecting the soundness of support piles etc. constructed from the ground surface to the ground.