JP3742678B2 - Deformation measurement jig for hollow existing piles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measuring jig for measuring the deformation of a hollow existing pile due to the influence of an earthquake or the like.
[0002]
[Prior art]
When structures such as buildings and bridges are damaged by an earthquake, these structures may damage not only the superstructure but also the foundation and piles. The foundation is harder to survey than the superstructure, and the extent of damage is difficult to clarify. The possibility of damage to the foundation can be pointed out from the analysis, but unless the extent of damage to the foundation, particularly the actual piles, is clarified, it is not possible to make decisions such as repairing the foundation or rebuilding the structure.
[0003]
Pile investigation is best done by digging up the entire length and observing the surface condition and measuring the deformation state, but it is rarely carried out due to cost, construction period, difficulty in digging up, etc.
[0004]
In general, the most common surveys of piles are (1) Pile head observation by digging only the pile head, (2) Observation with a borehole camera inside the pile, and (3) Light hitting of the pile head and its reflection Non-destructive inspection that measures waves.
[0005]
[Problems to be solved by the invention]
However, the method of (1) digging only the pile head and observing the pile head is an investigation of only the pile head, and the situation over the entire pile length cannot be grasped. Also, (2) observation with a borehole camera inside the pile and (3) nondestructive inspection to measure the reflected wave by tapping the pile head is effective when the width of the crack generated in the pile is large. However, it is often impossible to find minute cracks. In addition, the methods (2) and (3) cannot provide quantitative information such as the stress state of the entire pile. As described above, there has been no effective method for well examining the soundness or damage state of the entire pile.
[0006]
In view of the above circumstances, an object of the present invention is to provide a deformation measuring jig for a hollow existing pile that can measure a deformation amount of a hollow existing pile, a deformation distribution in a depth direction, and the like.
[0009]
[Means for Solving the Problems]
The deformation measuring jig for a hollow existing pile according to the invention of claim 1 inserts a rod into the hollow existing pile, and makes the upper and lower ends of the rod contact the same position in the circumferential direction of the inner peripheral surface of the existing pile. Hollow existing pile that measures deformation of existing pile by moving the rod in the depth direction inside the existing pile and measuring the relationship between the position in the depth direction of the rod and the inclination angle of the rod with respect to the vertical line The deformation measuring jig is formed on a rod inserted into a hollow existing pile, a contact plate disposed symmetrically in the vertical direction at the upper and lower ends of the rod, and a tip of the upper and lower contact plates, respectively. A contact portion that is in contact with a position that is spaced apart vertically at the same position in the circumferential direction of the inner peripheral surface of the existing pile, a biasing member that presses the upper and lower contact portions against the inner peripheral surface of the existing pile, and the upper and lower Contact part is the inner peripheral surface of the existing pile An inclinometer that measures an inclination angle of the rod with respect to a vertical line when contacted, the upper and lower contact plates are arranged so as to form a predetermined angle in plan view, and the two contact plates The urging member is provided on an extension of the bisector of the included angle , and the urging member has its upper and lower ends fixed to the position of the upper and lower contact plates and curved outwardly, and its central portion It consists of a single leaf spring that presses the contact part of all four contact plates evenly against the inner peripheral surface of the existing pile by the reaction force by contacting and stretching the inner surface of the existing pile. And
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a measuring jig 1 according to an embodiment of the present invention. This jig 1 has a rod 3 having an appropriate length that is sufficiently smaller than the entire length of the hollow existing pile K to be measured. The rod 3 is made of a square pipe, and as shown in FIG. 1A, a contact plate 5 protruding in a direction perpendicular to the length direction of the rod 3 is attached to the upper end and the lower end thereof. Two contact plates 5 are arranged vertically on the upper end and the lower end of the rod 3, respectively. In this embodiment, the two upper and lower contact plates 5, 5 are orthogonal to each other, for example, one of them is north-south. When the direction is matched, it is attached so that the other is oriented in the east-west direction. However, the two contact plates 5 and 5 are not necessarily orthogonal to each other, and the angle formed by them is arbitrary as long as it is within 180 degrees.
[0011]
The tip of each contact plate 5 is a contact portion 5a that contacts the inner peripheral surface of the pile K in a vertical posture, and the distance between the upper and lower contact portions 5a is set to 1 m here. A leaf spring (biasing member) 7 is attached to the side surface of the rod 3 opposite to the side on which the contact plate 5 is attached. The upper and lower ends of the leaf spring 7 are fixed to the upper and lower ends of the rod 3, and the outwardly convexly curved portions are in contact with the inner peripheral surface Ka of the pile K. As shown in the figure (b), the leaf spring 7 is arranged on the extension of the bisector of the included angle between the two upper and lower contact plates 5, 5, so that the leaf spring 7 is the inner peripheral surface of the pile K By stretching to Ka, the contact part 5a of each contact plate 5 on the opposite side is surely pressed against the inner peripheral surface Ka of the pile K with equal urging force.
[0012]
In addition, two inclinometers 10 </ b> A and 10 </ b> B for measuring the inclination angle of the rod 3 with respect to the vertical line are attached inside the rod 3. The two inclinometers 10A and 10B can measure inclinations in any two directions, here, the X-axis direction and the Y-axis direction orthogonal to each other.
[0013]
In addition, a joint rod 14 is connected to the upper end of the rod 3 through a universal joint 12, and the joint rod 14 is provided with a hook 15 for hooking a wire rope. Further, the connecting rod 16 can be sequentially connected to the upper end of the connecting rod 14.
[0014]
When measuring using this measuring jig 1, the jig 1 is inserted into the existing pile K from the pile head and held so as not to rotate, and the jig 1 is added and connected with the rod 16 in the depth direction. Move at 1m pitch. If it does so, the upper and lower contact plates 5 will contact two points of the inner peripheral surface Ka of the pile K which are the same positions in the circumferential direction and spaced apart by the action of the leaf spring 7. In this case, since the interval between the contact portions 5a is set to 1 m, the depth of the depth is measured by measuring the inclination angle of the rod 3 with the inclinometers 10A and 10B while bringing the contact plate 5 into contact with the inner peripheral surface Ka of the pile. The inclination angle (deformation angle) of the pile K in the section of the direction 1 m can be sequentially measured.
[0015]
As a result of the measurement, the relationship between the position of the pile in the depth direction and the deformation angle as shown in FIG. 2 can be obtained. In this case, the actually measured amount is a deformation angle, and by integrating the deformation angle, the relationship between the depth and the deformation amount as shown in FIG. 3 can be obtained. This figure shows the amount of horizontal displacement relative to the pile head. Also, the bending moment can be calculated by differentiating the deformation angle. Therefore, it becomes possible to know the deformation distribution and the stress situation over the entire pile length.
[0016]
In the present embodiment, since two inclinometers with different measurement directions are attached to the jig 1, for example, deformation angles in the east-west direction and the north-south direction can be measured simultaneously. Of course, only one inclinometer 1 may be used. In that case, the orientation of the jig 1 may be appropriately changed so that the measurement direction of the inclinometer matches the direction of measurement symmetry.
[0017]
Further, in order to improve the measurement accuracy, it is possible to cancel the error by taking data at a specific circumferential position of 0 degree and a reversed 180 degree position and setting the average value as the final measured value. .
[0018]
FIG. 4 shows the deformation amounts obtained from the data of the two inclinometers 10A and 10B, the broken line shows the measured value of 180 degrees inverted from 0 degree, and the solid line shows the average value thereof. As is clear from this figure, there is a possibility that an error of several millimeters may occur if the deformation amount is determined only by the measurement value that is not inverted. If the average of the inverted measurement values is obtained, the error can be eliminated and the measurement accuracy is improved. .
[0019]
In addition, by changing the distance between the upper and lower contact plates 5, the deformation angle of an arbitrary section such as an interval of 50 cm or an interval of 2 m can be measured. Further, by changing the size and attachment position of the contact plate 5 and the leaf spring 7, it is possible to measure any of the existing piles that are normally used.
[0020]
【The invention's effect】
As described above, according to the measurement jig of the present invention, since the relationship between the depth of the existing pile and the inclination angle is measured, the deformation property of the entire pile length can be clarified, and the deformation amount of the pile In addition, the stress state of the pile can be grasped quantitatively. In particular, two contact plates are arranged above and below the rod so as to form a predetermined angle, and a single plate as a biasing member on the extension of the bisector of the sandwich angle between the two contact plates Since the spring is provided, the contact portions of all four contact plates can be evenly and reliably pressed against the inner peripheral surface of the pile with only the single leaf spring , and the measurement accuracy can be improved.
[Brief description of the drawings]
1A and 1B are configuration diagrams of a measuring jig according to an embodiment of the present invention, in which FIG. 1A is a side view and FIG. 1B is a cross-sectional view taken along line Ib-Ib in FIG.
FIG. 2 is a characteristic diagram showing a relationship between a pile depth and a deformation angle obtained as a result of measurement using the measurement jig.
FIG. 3 is a characteristic diagram showing the relationship between pile depth and displacement obtained by integrating the data of FIG. 2;
FIG. 4 is a characteristic diagram showing a relationship between a pile depth and a horizontal displacement (deformation amount) obtained based on a result obtained by each inclinometer of the measuring jig.
[Explanation of symbols]
K hollow existing pile Ka inner peripheral surface 1 measuring jig 3 rod 5a contact portion 7 leaf spring (biasing member)
10A, 10B inclinometer

Claims (1)

Inserting a rod inside the hollow existing pile, bringing the upper and lower ends of the rod into contact with the same position in the circumferential direction of the inner peripheral surface of the existing pile, and moving the rod in the depth direction inside the existing pile, A deformation measuring jig for a hollow existing pile that measures the deformation of the existing pile by measuring the relationship between the position in the depth direction of the rod and the inclination angle with respect to the vertical line of the rod,
A rod inserted into a hollow existing pile, a contact plate disposed vertically symmetrically at the upper and lower ends of the rod, and an inner peripheral surface of the existing pile formed at the tip of the upper and lower contact plates, respectively Contact portions that are in contact with each other at positions spaced apart vertically at the same circumferential direction, a biasing member that presses the upper and lower contact portions against the inner peripheral surface of the existing pile, and the upper and lower contact portions are the inner peripheral surface of the existing pile. An inclinometer that measures an inclination angle with respect to a vertical line of the rod when contacting the rod,
Two upper and lower contact plates are arranged so as to form a predetermined angle in plan view, and the biasing member is provided on an extension of a bisector of the sandwich angle between the two contact plates. The upper and lower ends of the force member are fixed at the positions of the upper and lower contact plates and curved outwardly, and the central part is in contact with the inner surface of the existing pile and is stretched. A deformation measuring jig for a hollow existing pile, comprising a single leaf spring that uniformly presses the contact portion of the contact plate against the inner peripheral surface of the existing pile.

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