JPS58213920A - Measure for displacing amount of driven pile during driving period - Google Patents

Abstract

PURPOSE:To exactly measure even high-speed displacing amounts of a pile by a method in which a reference level provided to a pile is monitored optically and the displacement of the reference level is measured as an optical diplacement by an image sensor to obtain the displacing amount of the pile to be driven. CONSTITUTION:Incident light from a reference level 10 enters through a line 11 into a lense 13 and focuses into an image 10' at the position A' on an image sensor 14. When a pile 2 is struck, the image is moved from the position A' to the position B' as the reference level 10 moves. If time is put on the abscissa and displacing amount of the pile is put on the ordinate and the positions of the reference level 10 from the time of pile striking to the vibration stoppage are plotted, the penetration amounts are shown by the distance 17 and the rebound amounts are shown by the distance 18. The electrical signal of the image sensor 14, which is a device to generate electrical signals according to the amounts of incident light, is scanned in a treatment circuit 15 to obtain signal outputs to be shown on a graph.

Description

DETAILED DESCRIPTION OF THE INVENTION In civil engineering, construction work, etc., the present invention relates to the amount of temporary elastic contraction of a pile when driving a foundation pile into the ground with a pile driver, and the relationship between the surrounding surface of the pile and the soil in contact with the surrounding surface. This relates to a device that measures vertical vibration (rebound) of a pile caused by friction and elastic contraction of the soil at the tip of the pile, as well as the amount of penetration of the pile into the ground.

In general, in pile driving work, the bearing capacity of piles is mainly calculated using the pile driving formula, which is an empirical formula. According to the Architectural Institute of Japan's commentary on the architectural foundation structure design standards, the allowable bearing capacity of driven piles is determined by the following formula: Ra = is + tη - (1
) Ra: (Allowable supporting capacity of pile (1) S: Amount of penetration of pile (rr+) K: Amount of rebound (m) ef: Efficiency F: Impact energy (t-m) In actual work, at the design stage type of pile used,
The final driving depth, required supporting force, etc. have been determined, and the allowable supporting force obtained from the above (Equation 11 or (2)) in the vicinity of the final driving depth exceeds the supporting force required by the design. The pile driving work is completed0 Therefore, in the past, in pile driving work, the amount of penetration and rebound has always been measured at the final driving stage of each pile and kept as a record0 Measurements that have traditionally been carried out The method is mainly carried out either manually as shown in Figure 2 or using a simple machine as shown in Figure 3.The method shown in Figure 2 is
Attach the recording paper 3 to the stake λ, place a measuring stand q near that point, and hold the pencil by hand so that its tip touches the recording paper 3 attached to the stake λ, with the top of the measuring stand as the reference plane S. However, this method utilizes the fact that when a stake is hit by a hammer, the displacement of the stake is depicted on the recording paper as a line in the vertical direction. It is very dangerous because a person has to work at the bottom of the machine that repeatedly moves, and because the pencil is held by hand, it is difficult to keep it on the same plane at all times, and the accuracy is not good. It has the following disadvantages. In the method shown in FIG. 3, a support stand 7 is provided near the pile, a measuring device 9 having a contact rotating disk g configured to always come into pressure contact with the pile is installed on the support stand 7, and the pile is placed on the support stand 7. The vertical displacement of the pile is detected as the amount of rotation of the contact rotary disk S, and this is converted into an electric signal to measure the vertical displacement of the pile.

This method is complicated, and the contact rotating disk g does not always rotate completely following the impact of the displacement of the pile, resulting in variations in accuracy, and it is necessary to provide a fixed support near the pile. In addition, when setting piles on the pile driving machine, it is necessary to isolate the support stand 7 and measuring device t from the driving position. It has drawbacks such as being complicated and troublesome. Also the third
As a method for improving the followability of the contact rotating disc shown in the figure to the pile, there is a method described in Tokkosho, tI/-tIigo:l or % open/close 99-'Ig//Ko, both of which are shown in Figure 3. It has not been possible to completely overcome the aforementioned drawbacks of the method shown in .

The apparatus for measuring the amount of displacement of a pile during pile driving according to the present invention, as shown in FIG. 16. At an appropriate distance from the stake. The displacement of the reference line 10 or the reference point is detected as an optical displacement by an image sensor, and the output signal of the image sensor is used to measure the displacement of the pile being driven. It is something.

Therefore, the pile displacement measuring device according to the present invention has no part that comes into contact with the antibody, and can follow any high-speed displacement of the pile and measure the displacement of the pile accurately and with high precision. .

In Figures 1 to 6, the reference line 10 is initially at position A,
The incident light from the reference line 10 enters the lens system 13 through the line //, and forms an image 10' at the position AI on the image sensor-/9. When the stake is hit, the reference line 10 moves from the position A to the position B. At this time, the incident light from the reference line 10 also moves from the line // to the line //I, and the image sensor 7lA The image IOI of the upper reference line is also Bl from the AI position.
Move to the position.

In order to see the movement of the reference line 10 in more detail, the horizontal axis represents time and the vertical axis represents displacement, and the reference line is plotted from the moment the hammer hits the top of the pile until the pile stops photographing. If you plot the 10 positions, you will get a graph like the one in Figure 6. In this case, /71j is the amount of shellfish and 7g is the rebound. Looking at this from above, the image io' of the reference line 70 is displaced from the AI position to the 31 position, as shown in the part of the image sensor/lf light receiving part on the left side of the graph in the lb diagram. However, the position of the image 101 according to time undergoes exactly the same displacement as shown in the graph on the right side of the figure, and settles at the position B1. An image sensor is a device that generates an electrical signal according to the sensitivity of incident light.The image sensor is a device that generates an electrical signal according to the sensitivity of incident light. Alj in Hirogami
The elephant io' of fqr embroidery 10 has a clear difference in the amount of incident source from the upper 40th side, so the image sensor
A clear difference also occurs in the electrical signals generated from each pixel 7J). By appropriately scanning and processing the electrical signals generated on the image sensor/hiro in this way by the signal control and processing circuit/j, a signal output as shown in the graph of Fig. 6 can be obtained. 0 In the explanation of this embodiment, the reference line is shown as a simple black line, but various types can be considered as shown in Fig. 7.
In addition to displaying the reference line or reference point as a black and white contrast, the surface of the white part is treated to improve the reflection of light, and then it is illuminated with a light source, or the white part itself is used as a light-emitting surface. There is also a method of using a line or a light emitting point and further processing the surface of the black part to improve light absorption.

Various types of displacement measurement devices for driven piles have been devised and manufactured over the years, but they have not been widely used, and even today, most labor sites, etc.
The method shown in the figure is used. The device according to the invention comprises:
By utilizing technology that has developed rapidly in recent years, especially LSI technology, it is possible to make the device itself as small as a small camera. In addition, in actual pile driving work, the bearing capacity of the pile determined by equations (1) and (2) shown above is the most important, so in general, the cumulative penetration of the pile [
K is determined by measuring the part of the driven pile that protrudes above the ground with a tape measure, etc., and when it is determined that the pile has reached near the planned depth, the amount of penetration is determined using the method shown in the TAX diagram. Measure the amount of penetration and rebound about 10 times, find the average value for each of the amount of penetration and amount of rebound, and substitute this into formula (1) or (2) to calculate the supporting force, which calculates the design supporting force.
Repeat the same measurement several times until the pile buckles, and when the calculated bearing capacity exceeds the stepped bearing capacity, complete the driving work of the pile and write the required information on the paper used for the measurement. We fill in the information and save it as a record. That is, in the driving work of piles, the amount of penetration and rebound of the pile due to impact near the planned penetration depth are most important and must be kept as records. In general, what is the amount of penetration of a pile in response to a single blow near the planned penetration depth? When using the device according to the present invention to measure the displacement of piles only in the vicinity of the planned purchase depth, a tracked type equipped with a pile driver is used, as shown in Figure g. If the device according to the present invention is installed in the lower part of a vehicle so that the device according to the present invention can also be operated from the driver's seat of the vehicle that operates the pile driving machine, pile driving will not be a scheduled task that requires manual labor. When it is determined that the penetration depth has been reached, a reference line is pasted or drawn slightly above the ground level on the vehicle side of the pile, and the displacement of the pile is automatically and safely and accurately measured. It can be measured.
11 or (2), input the output signal from the device according to the present invention, and easily calculate and display and record the supporting force corresponding to each blow. The device according to the invention makes it possible to provide numerous conveniences when driving piles.

[Brief explanation of drawings]

Figure 1 is a diagram showing the state of driving pile driving work, and Figures 2 and 3 are diagrams showing the conventional method of measuring pile penetration and rebound retention during actual pile driving work. It shows you how to do it. A further diagram shows an example of measuring the penetration μ and rebound amount of a pile using the device according to the present invention,
FIG. S is a block diagram showing the principle of the device according to the invention. FIG. 6 shows the displacement of the pile as a function of time when the pile is struck and a portion of the image sensor used in the device according to the invention. Figure 7 shows an example of how to set up the base line or reference point to be marked on a pile.9 An example of when installed is shown. /- Part of hammer, - One stake, 3- Recording paper, Goo measurement stand,
S-regular plate, B-pencil, 7-support stand, K-contact rotating disk, data measuring device, 10-reference line, 101-image on image sensor of reference line, //, //1-incident light , /2, /,
2'- Measuring device according to the invention, /3- Lens system, /l-
Image sensor, 7.5-Signal control and processing circuit, /
6-Signal output, /7-Penetration amount, 1g-Rebound amount, A
, B - position of base M before and after impact, A', B' - position of image of reference line on image sensor before and after impact 14 (1), (1), (IID, 0V ) - Examples of how to set reference lines or reference points. Applicants Takashi Ito Gobue 1st Imo 2nd 3rd 10th 5th 14" stone 6th

Claims (1)

[Claims] A reference line or reference point marked on the pile body to be driven, an optical system consisting of a lens system for monitoring the reference line, an image sensor installed at the focal position of the optical system, and a reference point of the image sensor. It is composed of an electronic system consisting of a signal processing device that processes signal output and a trap, and can measure the displacement of the reference line or reference point marked on the antibody without contacting the antibody to be placed.
It is characterized by being able to accurately and highly accurately measure the impulsive displacement of the deposited antibody by processing the output signal of the image sensor as the displacement of the image of the reference point or reference line on the image sensor. Displacement measuring device 0 during driving pile driving