JPH0633460A - Automatic measuring method and device for dynamic bearing capacity of precast pile - Google Patents

Abstract

PURPOSE:To avoid hazards for the safety of workers, demand a dynamic bearing capacity for a precast pile and determine the completion of pile casting operation in an automatic mode. CONSTITUTION:A laser transmitter 1 is mounted to a pile under casting operation. A laser receiver 2 designed to receive laser light 12 is mounted at a specified position. A computing element 3 is mounted to the receiver 2. The laser light 12 under casting is received by the receiver 2. The computing element 3 computes a dynamic bearing capacity of a pile 6 from measured values which cover changes in the height of the laser light 12 based on the received information for the sinking and rebound of the pile 6. Then, comparison is made between the dynamic bearing capacity thus obtained and a static bearing capacity preliminarily input into the computing element 3 capable of ending pile casting operation. Whether pile casting be ended or not is determined based on the comparison result.

Description

Detailed Description of the Invention

[0001]

This invention relates to a method of measuring a dynamic bearing force when a precast pile, such as a steel pipe pile, a PHC pile or a PC pile, is driven by a hammer striking in the foundation work in the construction work. And the device.

[0002]

2. Description of the Related Art Among foundation works in construction work, in the case where a precast pile represented by steel pipe piles, PHC piles, PC piles, etc. is struck by a hammer, dynamic allowable support of the precast piles is carried out. A force (hereinafter referred to as "dynamic bearing force") measurement is performed. FIG. 4 is a perspective view showing a conventional working method for measuring the dynamic bearing capacity of an existing pile.

The conventional dynamic bearing force measurement of prefabricated piles is performed by the following steps. First, the worker 8 directly approaches the pile 6 that is being driven by the diesel or hydraulic pile hammer 7 and glues the recording paper (graph paper) 9 on the surface of the pile 6. Then, the behavior of the pile 6 in the up-and-down direction caused by hammering is recorded with the pencil 10. Reference numeral 11 is a behavior locus drawn on the graph paper 9. Then, after recording, this graph paper 9
Peel off and take it back, and calculate the dynamic bearing capacity of the pile by hand from the amount of sinking per hammer hit of the pile, the amount of rebound, the weight of the hammer used, and the hammer drop height.

[0004]

However, the above-mentioned conventional measuring method by the worker is very dangerous because the worker has to go under the pile driving hammer which is in operation. Further, when using a diesel hammer, the scattered diesel oil is put on from above the head, and work clothes and the like are soiled.

Further, in order to continuously measure the sinking amount and the rebound amount of the pile by several hammer hits, the pencil is laterally moved for each hammer hit while keeping the height of holding the pencil constant. Have to move to. These tasks are difficult and inaccurate when moving on the ground at the foot of a stake hammer.

Furthermore, after collecting the pile driving data, these data are once brought back from the site to another department, and then the dynamic bearing capacity of the pile is calculated using a known formula, but at that time, it is already applicable. In most cases, the driving of piles has been completed, and it takes too much time to manage pile driving by calculating the dynamic bearing capacity.

Therefore, an object of the present invention is to provide a dynamic support force for a pile automatically, accurately, quickly and safely, without requiring an operator to approach a hammer, to determine the completion of driving. An object of the present invention is to provide an automatic pile dynamic bearing force measuring method and device.

[0008]

SUMMARY OF THE INVENTION The method of the present invention is an automatic pile dynamic bearing capacity measuring method for measuring the dynamic bearing capacity of a pile being driven by a hammer. A transmitter is attached, a laser receiver for receiving the laser light emitted from the laser transmitter is provided at a predetermined position, an arithmetic unit is attached to the laser receiver, and the laser light during driving is set to the laser receiver. And calculating the dynamic support force of the pile from the measured value of the change in the height of the laser light based on the sinking and rebound of the pile received by the calculator, and then obtaining the obtained dynamic support force. The force is compared with a static permissible supporting force which is inputted to the computing unit in advance and which can end the driving of the pile, and it is determined whether or not the driving of the pile is ended based on the result of the comparison. I have. The device of the present invention comprises a laser transmitter mounted on a pile being hammered, a laser receiver provided at a predetermined position for receiving laser light emitted from the laser transmitter, and a laser transmitter. The dynamic bearing force of the pile is calculated from the measured value of the change in the height of the laser light based on the sinking and rebound of the pile inside, and the obtained dynamic bearing force and the pre-entered placement of the pile are performed. It is characterized in that it comprises an arithmetic unit for comparing with a static permissible supporting force that can be ended and for judging whether or not the driving of the pile is ended based on the comparison result.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention.

As shown in FIG. 1, the present invention uses a laser transmitter 1, a laser receiver 2, an arithmetic unit (microcomputer) 3 and an output printer 4. It is preferable to use a cordless type or a rechargeable type as the laser transmitter 1. A magnet (not shown) is attached to the laser transmitter 1. Furthermore, laser transmitter 1
An auxiliary steel band 5 can be attached to the. Thereby, the laser transmitter 1 can be mounted on the pile 6 by one touch by magnetic force when the pile 6 is a steel pipe pile or the like and by the steel band 5 when the pile 6 is a PHC pile or the like. Instead of a laser, a light wave transmitter / receiver may be used.

The laser receiver 2 is provided integrally with a box containing a microcomputer 3 and a printer 4. The laser receiving surface of the laser receiver 2 has a certain area so that it can be used at a position 10 to 20 m away from the laser transmitter 1 even when there is a slight difference in height of the ground. 7 is a pile driving hammer, diesel type or hydraulic type (drop hammer)
Is used.

The laser light 12 emitted from the laser transmitter 1 is received by the laser receiver 2. When the pile 6 is driven by the pile hammer 7, the laser light level (the height of the laser light) also changes following the sinking of the pile 6 caused by the driving and the vertical movement due to the rebound. The dynamic bearing force is calculated by the microcomputer 3 from the data of the laser light level change received by the laser receiver 2 and compared with the static allowable bearing force. Then, the result is printed (printed out) by the printer 4. 13
Is an alarm device attached to the computing unit 3 for giving a warning of the end of pile driving, and when the dynamic bearing capacity exceeds the static allowable bearing capacity, the pile driver is instructed by a warning that the pile driving can be finished. Inform. The warning method is buzzer or red lamp lighting.

Next, the calculation and determination methods from dynamic recording (waveform) to pile stop management will be described with reference to the drawings. FIG. 2 is a flowchart explaining the supporting force measuring step.

(1) Plot the relationship between time and laser light level based on the received laser light level (height). FIG. 3 is a graph showing the relationship between time and laser light level.

(2) The inflection point (mountain) in each figure from one hit to the last hit is recorded from the data of the time from the recorded last hit to the time of hit 10 times back and the laser light level data. And the valley) and the laser light level at that point is L _1B , L _1C ... L _10B , L _10C , the sinking amount and rebound amount of the pile per 10 hits are as follows. Become. Settlement amount: ΣS = (L _1B −L _10B ), Rebound amount: Formula 1.

[0016]

[Equation 1]

Next, the average subsidence amount and the average rebound amount per impact are calculated. Average subsidence amount: S = ΣS / 10. Average rebound amount: K = ΣK / 10.

(3) The dynamic bearing force is calculated by the following equation (2).

[0019]

[Equation 2]

[0020] Here, R _a: Dynamic bearing capacity piles (t) F _s: e _f a safety factor = 3: F and Efficiency = 0.5: For impact energy drop hammer (hydraulic hammer); F = WH, in the case of a diesel hammer; F = 2WH, W: hammer weight (t) H: hammer drop height (m) S: average pile sinking (m) K: average rebounding pile (m). Data other than S and K should be entered in advance.

(4) Comparison with required static load capacity of required pile. Static allowable bearing capacity (hereinafter referred to as "static allowable bearing capacity") R _a0 obtained from the pile type, pile diameter or supporting layer that has been input,
Performing comparison between dynamic supporting force R _a calculated in the above (3). The static permissible supporting force is a supporting force capable of ending the driving of the pile. The static permissible supporting force R _a0 is set according to the pile type, pile diameter, or supporting layer, that is, the type of ground to be used, and is input to the computing unit (microcomputer) in advance.

(5) Judgment of completion of pile driving. (a) When R _a ≧ R _a0 : It is judged that pile driving can be completed. (b) When R _a <R _a0 : _Judge that it is necessary to continue pile driving.

(6) Output of calculation result. The following is displayed by the printer. (a) A graph showing the relationship between time and laser light level calculated in (1) (Fig. 3). (b) Dynamic bearing capacity of pile calculated in (2). (c) Judgment result of pile driving completion in (3).

(7) Alarm. When the dynamic bearing capacity exceeds the static allowable bearing capacity (R _a ≧ R _a0 ), a warning is given to the pile hitter by an alarm indicating that pile driving can be completed.
The warning method is buzzer or red lamp lighting.

[0025]

The laser transmitter according to the present invention is a compact and lightweight device in which a rechargeable storage battery serving as a power source and a laser light transmitter are integrated. A magnet is attached to the back surface of the device and can be attached to a metal with one touch. And When using it for PHC piles, wrap another steel band around the pile,
The above laser transmitter is attached to this. This allows
The only work done by the workers near the pile is to install this laser transmitter, and the lower part of the hammer is unmanned during casting, which greatly reduces the risk and also poses the problem of contaminating work clothes with diesel hammer splash oil. Disappear.

Further, the laser receiver captures the laser light from the laser transmitter on the light receiving surface and sends the data to the microcomputer. In the microcomputer, from the behavior of the pile being sent,
The pile sinking amount and rebound amount per hammering hammer are calculated, and the dynamic bearing force of the pile is calculated by combining the hammer weight and the hammer drop height that have already been input.

By printing the calculation result by the built-in printer, it becomes possible to manage the bearing capacity on the spot at the pile driving site. If the dynamic bearing capacity exceeds the static allowable bearing capacity, the pile driver will be informed by a buzzer or an alarm by lighting a red lamp that the pile driving can be completed.

[0028]

As described above, according to the present invention, the sinking amount and the rebound amount of the pile during driving are automatically measured by using the laser beam, and the dynamic bearing force calculation is performed consistently. Since it is possible to manage the bearing capacity of the pile on site,
The work efficiency is significantly improved, and by performing the work by remote control, industrially useful effects such as danger and pollution of workers are eliminated.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a supporting force measuring step.

FIG. 3 is a graph showing the relationship between time and laser light level.

FIG. 4 is a perspective view showing a conventional working method for measuring the dynamic bearing capacity of an existing pile. 1 Laser transmitter 2 Laser receiver 3 Microcomputer 4 Printer 5 Steel band 6 Pile 7 Pile hammer 8 Worker 9 Graph paper 10 Pencil 11 Trajectory 12 Laser light 13 Alarm device.

Claims (2)

[Claims] 1. A method for automatically measuring the dynamic bearing capacity of an existing pile for measuring the dynamic bearing capacity of a pile being driven by a hammer,
A laser transmitter is attached to the pile being placed, a laser receiver for receiving the laser light emitted from the laser transmitter is provided at a predetermined position, and an arithmetic unit is attached to the laser receiver, Laser light is received by the laser receiver, the calculator calculates the dynamic bearing force of the pile from the measured value of the change in the height of the laser light based on the received settlement and rebound of the pile, and then , Comparing the obtained dynamic bearing force with a static permissible bearing force which is inputted to the arithmetic unit in advance and capable of ending the driving of the pile, and whether or not the driving of the pile is ended based on the result of the comparison. A method for automatically measuring the dynamic bearing capacity of an existing pile, which is characterized by determining 2. A laser transmitter mounted on a pile being hammered, a laser receiver provided at a predetermined position for receiving a laser beam emitted from the laser transmitter, and In which the dynamic bearing force of the pile is calculated from the measured value of the change in the height of the laser light based on the sinking and rebound of the pile, and the obtained dynamic bearing force and pre-entered placing of the pile are completed. A ready-made pile dynamic bearing capacity automatic measurement characterized by comprising a calculator for comparing with a possible static allowable bearing capacity and judging whether or not the driving of the pile is completed based on the result of the comparison. apparatus.