JP2007003453A - Quick load testing machine of pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quick load testing machine of a pile, which is constituted so as to realize the transmission of a predetermined impact force caused by the falling of a weight to the head of the pile in a predetermined transmission time and made small-sized. <P>SOLUTION: The quick load testing machine 1 of the pile 50 has: a falling impact load transmitting means 2 using a hydraulic cylinder 3 for receiving the falling impact load due to the falling of the weight 60 by the cylinder rod 4, which is arranged between the head 51 of the pile 50 and the weight 60 and has a weight receiver 8 using a buffering material provided to its top part, to transmit it to the head 51 of the pile 50 through the cylinder rod 4 and the buffering body 14 arranged to its bottom part; and a hydraulic pressure adjusting means 20 for adjusting the transmission force and transmission time of the impact load to the head 51 of the pile 50 from the cylinder rod 4 of the hydraulic cylinder 3 by the supply of oil having a predetermined oil pressure to the upper and lower cylinder chambers 11 and 12 of the hydraulic cylinder 3 and the receiving of the discharge oil from the upper and lower cylinder chambers 11 and 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rapid loading test apparatus for piles used in the construction of civil engineering and building structures.

  It is extremely important to know the bearing capacity of piles accurately when constructing civil engineering and building structures. Therefore, conventionally, as this type of test, a so-called static loading test or a so-called impact loading test by hammering (loading time: about 0.01 to 0.02 seconds) is performed.

  Moreover, recently, as a method for grasping accurate bearing capacity of piles and economically and rationally, a so-called rapid loading test (loading time: 0.05 to 0.2) located between the static loading test and the impact loading test. Minor second) is also being carried out. In this method, rubber or metal springs, dampers, etc. are placed in parallel between the pile and the weight (monken), the impact force is applied to the pile and the supporting force is inspected, and the reaction force is applied to the pile head. This is a test method in which the body is placed and impact force is applied by using the explosive combustion force of high-pressure gas or explosive to inspect the support force.

  The pile bearing capacity test method has changed to the rapid loading test method, but at present, a satisfactory testing machine has not been completed. The main cause is that the apparatus becomes large if a structure that secures a loading time of about 0.1 seconds is adopted. For example, in the case of a bearing capacity test of a 300 mmφ pile, a rapid loading tester becomes large with a diameter of 650 mmφ and a height of about 1 m in a structure employing a spring / dumbar system.

  Also, in the case of another type of rapid loading test, it is often impossible to make it smaller than this. For this reason, a testing machine with a higher center of gravity and a significantly larger area than the pile will be mounted on the test pile, and the device will not only roll in the vertical direction but also perform rolling and pitching when testing the weight to drop on the pile head. As a result, a problem occurs in the reliability of the test data, and an excessive load is expected to cause a problem in the life of the apparatus.

Patent Document 1 proposes a rapid loading test apparatus for piles according to the proposal of the applicant of the present application. In the case of Patent Document 1, a weight is combined with a load transmission means including an inertial mass, a damping element, and an elastic body so that a drop impact load is applied to the pile head. In this case, since the load transmission means is configured using an inertial mass, a damping element, and an elastic body, it includes a problem that it is difficult to make the configuration compact and compact.
JP 2004-317364 A

  The problem to be solved by the present invention is to realize a loading time of about 0.06 seconds to 0.2 seconds for the weight, which is the main purpose of the rapid loading test on the pile head, and to apply a predetermined impact force to the pile. There is no rapid loading test device for piles that can be transmitted and that further downsizes the device.

  The present invention relates to a rapid loading test apparatus for a pile that performs a rapid loading test by transmitting a drop impact load due to the falling of the weight to the pile head, and is disposed between the pile head and the weight, and is loaded by a cylinder rod. Drop impact load transmission means using a hydraulic cylinder that receives a drop impact load due to falling of the weight and transmits it to the pile head through this cylinder rod, and transmission of the impact load from the cylinder rod of the hydraulic cylinder to the pile head The main feature is that it has a hydraulic pressure adjusting means for adjusting the force and transmission time by adjusting the hydraulic pressure acting on the cylinder rod.

The present invention has the following effects.
According to the first and second aspects of the present invention, a drop impact caused by dropping a weight by a small hydraulic cylinder, such as a hydraulic cylinder cylinder rod, which is a drop impact load transmitting means disposed between the pile head and the weight. A rapid loading test can be performed by receiving a load and transmitting a drop impact load to the pile head via this cylinder rod. At this time, by adjusting the hydraulic pressure acting on the cylinder rod by the hydraulic pressure adjusting means, for example, the hydraulic pressure, the transmission force and transmission time of the impact load to the pile head can be variously adjusted.

  According to invention of Claim 3, the cylinder rod which arrange | positions the small hydraulic cylinder which is a drop impact load transmission means between a pile head and a weight, and is equipped with the weight receiving body using the shock absorbing material on the top part. By receiving a drop impact load due to the fall of the weight, a rapid load test can be performed by transmitting the drop impact load to the pile head via this cylinder rod. At this time, by supplying oil having a predetermined oil pressure to the first and second cylinder chambers of the hydraulic cylinder and receiving discharged oil from the first and second cylinder chambers by the hydraulic pressure adjusting means, Various adjustments can be made to the transmission force and transmission time of the impact load on the rim.

  According to the invention of claim 4, in the invention of any one of claims 1 to 3, it has the vertical settlement guide mechanism for guiding the vertical settlement of the cylinder rod when the weight is dropped. By dropping the rod straight down vertically, it is possible to accurately transmit the drop impact load to the pile head.

  According to the invention of claim 5, in the invention of any one of claims 1 to 4, the oil pressure adjustment means adjusts the oil pressure supplied to the first and second cylinder chambers of the hydraulic cylinder, and the first and second oil. By adjusting the amount of oil discharged from the cylinder chamber, the transmission time of the impact load to the pile head can be set to 0.05 to 0.2 seconds.

  The present invention provides a rapid loading test apparatus for a pile that realizes transmission of a predetermined impact force by a weight to a pile head in a transmission time of about 0.06 seconds to 0.2 seconds and has a downsized apparatus. The cylinder rod and the bottom of the cylinder rod, which is placed between the pile head and the weight and receives a drop impact load due to the falling of the weight by a cylinder rod having a weight receiver using a cushioning material at the top. Drop impact load transmission means using a hydraulic cylinder that transmits to the pile head through a shock absorber using a cushioning material arranged in the shock absorber, and the transmission force and transmission time of the impact load from the cylinder rod of the hydraulic cylinder to the pile head The adjustment is realized by a configuration having hydraulic pressure adjusting means for performing adjustment by supplying oil having a predetermined hydraulic pressure to the first and second cylinder chambers of the hydraulic cylinder and receiving discharged oil from the first and second cylinder chambers. It was.

  Hereinafter, a rapid loading test apparatus for piles according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the rapid loading test apparatus 1 for a pile 50 according to this embodiment is disposed on a pile head 51 of the pile 50 and transmits a drop impact load accompanying the fall of the weight 60 to the pile head 51. Drop impact load transmission means 2 using the hydraulic cylinder 3, supply of oil to the hydraulic cylinder 3 of the drop impact load transmission means 2, reception of oil discharged from the hydraulic cylinder 3, and accompanying falling of the weight 60 And a hydraulic pressure adjusting means 20 that adjusts the transmission force and transmission time of the drop impact load to the pile head 51.

  The drop impact load transmission means 2 includes a cylinder holder 5 for fixing and holding the upper outer periphery of the cylindrical cylinder body 3A in the hydraulic cylinder 3 at a fixed position above the pile head 51 of the pile 50 and in a vertical arrangement. is doing. That is, the upper portion of the cylinder body 3A is fitted and held in a hole provided in the center of the cylinder holder 5.

  An upper hydraulic receiver 6 is fitted into the upper inner peripheral portion of the cylinder body 3A so that the cylinder rod 4 penetrates slidably and protrudes upward, and is formed at the upper end of the upper hydraulic receiver 6. The flange 6c is joined to the upper surface of the cylinder holder 5, and the flange 6c is fastened and fixed to the cylinder holder 5 with bolts 7, so that the upper hydraulic receiver 6 and the cylinder body 3A are integrated with the cylinder holder 5. Attached.

  A shock absorber is used at the upper end of the cylinder rod 4 projecting upward from the upper hydraulic receptacle 6 to prevent noise having a planar shape of a deformed octagon as shown in FIG. The weight receiver 8 is disposed horizontally with the upper end of the cylinder rod 4 joined to the lower surface of the central portion thereof.

  The weight receiver 8 is provided with screw portions 9a, 9a having a pair of round bar-like hanging bodies 9, 9 provided at the upper ends thereof at the position occupying the outside of the flange 6c. It is attached in a state where it is screwed from the side and is suspended in a vertical arrangement.

  Further, the lower ends of the pair of hanging bodies 9, 9 are slidably passed through a pair of extraction holes 5 a, 5 a provided in the vicinity of the outer peripheral portion of the cylinder holding body 5 and are suspended downward. The pair of hanging bodies 9 and 9 function as a vertical sinking guide mechanism that sinks the weight receiver 8 and therefore the cylinder rod 4 vertically downward when the weight 60 falls.

  Between the inner periphery of the upper hydraulic receiver 6 and the outer periphery of the cylinder rod 4, between the outer periphery of the upper hydraulic receiver 6 and the inner periphery of the cylinder body 3A, an O-ring 6a, 6b is fitted.

At a position below the upper hydraulic receiver 6 in the cylinder body 3A, a substantially cylindrical lower hydraulic receiver 10 is provided at a predetermined interval so as to form an upper cylinder chamber 11 which is a second cylinder chamber. It is arranged. The lower hydraulic receiving body 10 has an inner peripheral portion thereof integrally fitted to a lower outer periphery of the cylinder rod 4, and an outer peripheral portion thereof is slidably fitted to the inner peripheral surface of the cylinder body 3A. ing.
Further, the lower end surface of the lower hydraulic receiver 10 and the lower end surface of the cylinder rod 4 are arranged to be the same surface.

  An O-ring 10a is fitted between the outer periphery of the lower hydraulic receiver 10 and the inner periphery of the cylinder body 3A.

  A disk-shaped buffer body 14 is attached to a lower portion of the cylinder body 3A at the position where the lower hydraulic receiver 10 is fitted using a cylindrical cover cylinder 13. This shock absorber 14 is intended to prevent noise when it comes into contact with the pile head 51.

  An outer periphery of a lower end portion of the lower hydraulic receiver 10 is formed to have a slightly smaller diameter than other portions, and is a first cylinder chamber between the lower end side of the lower hydraulic receiver 10 and the buffer body 14. A lower cylinder chamber 12 is formed.

  On the wall surface of the cylinder body 3A, there is provided an upper port 15 for introducing and discharging oil at a position facing the upper cylinder chamber 11, and a lower port for introducing and discharging oil at a position facing the lower cylinder chamber 12. A port 16 is provided.

Next, the hydraulic pressure adjusting means 20 will be described in detail with reference to FIGS.
The hydraulic pressure adjusting means 20 is a frame that has a rectangular parallelepiped shape as a whole, for example, four columns 23 are erected from the four corners of a block-shaped base 22 and a block-shaped upper plate 24 is attached to the upper end of each column 23. A body 21 is provided.

  An electric hydraulic unit 28 including an electric motor 25, a high-pressure pump 26, and a low-pressure pump 27 and an oil tank 29 are incorporated on the base 22 of the frame body 21. The upper plate 24 incorporates an accumulator 30 and a pressure gauge 37. In FIG. 1, reference numeral 39 denotes a nut for fastening the upper and lower ends of each column 23 to the upper plate 24 and the base 22 with screws.

  The accumulator 30 has nitrogen gas sealed therein at a constant pressure, and removes oil that is removed when the weight 60 collides with the hydraulic shilling 3, that is, when the cylinder rod 4 of the hydraulic cylinder 3 sinks. It plays a role in mitigating acceptance shock. However, since the volume of the accumulator 30 affects the impact loading time, it should be noted that it is sufficiently calculated.

Next, the hydraulic circuit system of the hydraulic pressure adjusting means 20 will be described in detail with reference to FIG.
The hydraulic circuit system includes a first stop valve 41 for piping to be connected to the lower port 16, and a second stop valve 42 for piping to be connected to the upper port 15. The hydraulic circuit system includes a high pressure pump 26 and a low pressure pump 27 that supply oil having a predetermined oil pressure to the cylinder body 3A, and a motor 25 that rotationally drives the high pressure pump 26 and the low pressure pump 27. Yes.

  Further, the hydraulic circuit system is connected to the discharge side of the high-pressure pump 26 via a check valve 31 and connected between the 4-port switch valve 32 and the first stop valve 41. A check valve 33 (external pilot type), and a pressure gauge 37 and a relief valve 34 connected to a pipe branched from the pipe between the check valve 33 and the first check valve 41. . The 4-port switching valve 32 is also connected to the second stop valve 42 and the accumulator 30.

  The 4-port switching valve 32 is configured as an open center type, includes electromagnetic solenoids SOLA and SOLB, and further includes a spring.

  The hydraulic circuit system further includes two sequence valves 35 (internal pilot type) and a sequence valve 36 (internal pilot type). Each inflow side of the sequence valve 35 and the sequence valve 36 is connected via a check valve 38, and the discharge side of the low-pressure pump 27 is connected to the inflow side of the sequence valve 36. The discharge side of the low pressure pump 27 is connected to the high pressure pump 26. Further, the sequence valve 36 employs an external pilot system that operates with the pressure of the pipe line between the check valve 31 and the 4-port switching valve 32.

  Each discharge side of the sequence valve 35 and the sequence valve 36 is connected to an oil tank 29. Further, the lower port 16 and the accumulator 30 are connected, and the upper port 15 and the oil tank 29 are connected.

  Next, operation | movement of the rapid loading test apparatus 1 of the pile 50 which concerns on a present Example mentioned above is demonstrated.

  The drop impact load transmission means 2 in the rapid loading test apparatus 1 of the pile 50 according to the present embodiment is installed on the pile head 51 of the pile 50, and the cylinder holder 5 is sufficiently provided so that the hydraulic cylinder 3 is arranged vertically. Fix in place with strength. Thus, the first stop valve 41 and the second stop valve 42 are opened, the electromagnetic solenoid SOLA of the four-port switching valve 32 in the hydraulic pressure adjusting means 20 is operated, and the first pipe body 32A communicates with the hydraulic cylinder 3. Put in the road.

  In this state, for example, the motor 25 is started, and oil having a predetermined hydraulic pressure is sent from the high-pressure pump 26 (or the low-pressure pump 27) to the lower port 16 via the 4-port switching valve 32 and the first stop valve 41. As a result, oil having a predetermined hydraulic pressure is injected into the lower cylinder chamber 12, and the lower hydraulic receiver 10 and thus the cylinder rod 4 are displaced vertically upward.

  Accordingly, the oil previously injected into the upper cylinder chamber 11 reaches the hydraulic pressure adjusting means 20 from the upper port 15 through the second stop valve 42 and further passes through the first valve body 32A of the four-port switching valve 32. Then, it is transferred into the oil tank 29.

  As described above, the cylinder rod 4 of the hydraulic cylinder 3 is displaced upward along the weight receiver 8 vertically by a predetermined stroke.

  Next, in order to perform a rapid loading test of the pile 50, the weight 60 (for example, a mass of 4 tons) is dropped onto the weight receiver 8 of the drop impact load transmission means 2. As the weight 60 falls, the drop impact load is transmitted to the weight receiver 8 and the cylinder rod 4, and further to the pile head 51 via the buffer body 14 by the downward displacement of the cylinder rod 4 for a predetermined stroke. Is done.

  In this way, the drop impact load due to the fall of the weight 60 can be applied to the pile head 51 via the cylinder rod 4, and the rapid loading test of the pile 50 can be executed.

  When the cylinder rod 4 is lowered by a predetermined stroke, the lower hydraulic receiver 10 is also lowered in conjunction with this, so that the oil in the lower cylinder chamber 12 is discharged from the lower port 16. The accumulator 30 is sent to accumulate pressure in the accumulator 30. By such an operation, the impact of the hydraulic cylinder 3 itself accompanying the fall of the weight 60 is reduced.

  Further, as the lower hydraulic pressure receiver 10 is lowered, the hydraulic pressure in the upper cylinder chamber 11 is reduced, or in this case, the electromagnetic solenoid SOLB of the 4-port switching valve 32 is operated, and the second valve body 32B is operated. Is put into a main line communicating with the hydraulic cylinder 3, and the high pressure pump 26 (or the low pressure pump 27) is further operated.

  As a result, oil having a predetermined hydraulic pressure sent from the high-pressure pump 26 (or low-pressure pump 27) is sent to the upper port 15 via the second valve body 32B and the second stop valve 42, and into the upper cylinder chamber 11. The oil is injected so as to have a predetermined hydraulic pressure, and is returned to the same state as before the weight 60 is dropped.

  In the hydraulic pressure adjusting means 20, the high pressure pump 26 (or the low pressure pump 27) exhibits a function of replenishing oil when the accumulated oil in the accumulator 30 is insufficient or disappears. By turning on the sequence valve 35 or 36, the function of sending (circulating) oil also into the oil tank 29 is exhibited.

  According to the rapid loading test device 1 of the pile 50 according to the present embodiment described above, the loading time for the pile 50 can be freely adjusted between 0.06 seconds and 0.2 seconds, and the pile 50 It is possible to accurately transmit the loading load due to the drop of the weight 60 necessary for the loading test with a significantly smaller device configuration as compared with the conventional case.

Here, a specific example of the rapid loading test apparatus 1 according to the present embodiment will be described.
Mass of falling weight (monken) 4 tons (ton)
Transmission force to the pile 100tonf
Loading time 0.1 sec
Then,
The elastic (spring) constant k of the hydraulic shilling can be obtained by the following equation (1). If the mass of the weight is known, the necessary natural period can be obtained.

In Equation 1, A2 = Cylinder rod lower area A1 = Cylinder area γ = Accumulator gas sealing pressure / Cylinder maximum operating pressure F = Drag Va = Accumulator volume A1L = Cylinder volume Vp = Piping volume

Next, the transmission force to the pile head can be obtained by multiplying the elastic constant k of the hydraulic shilling obtained in Equation 1 by the necessary stroke. The specifications obtained from this result are as follows.
Hydraulic cylinder 200mmφ × 140mmφ × 60st (35Mpa)
Accumulator 2.8 liters (for 33 Mpa) x 2 high-pressure charge hydraulic pump units (portable) up to 35 Mpa
Hydraulic tank 1 liter Other Hydraulic hose Hydraulic gauge Relief valve

  Thus, for example, when compared with a rapid loading test apparatus having a transmission force of 100 tons, in the case of the rapid loading test apparatus of this embodiment, the hydraulic cylinder installed on the pile head has an outer diameter of about 350 mmφ, A height of about 330 mm is possible, and an equivalent performance can be secured with a size of about 1/10 of the volume.

  Furthermore, in the actual rapid loading test, the time scale and the transmission force can be easily adjusted within a certain range at the site. An example of the adjustment range in this case is shown below. The example shown below is obtained based on a loading time of 0.1 seconds and a transmission load of 100 tons.

Loading time Loading load 0.08 seconds 156.3 ton
0.09 seconds 123.5 ton
0.1 second 100 ton
0.11 second 82.7 ton
0.12 seconds 69.5 ton
0.14 seconds 51.0 ton

  As described above, the configuration using the hydraulic cylinder 3 as shown in FIG. 1 can realize the rapid loading test apparatus 1 having a small stroke and a large pressure during transmission of the loading load, and thus the rapid loading test apparatus 1. The whole becomes very small. Accordingly, it is difficult for the rapid loading test apparatus 1 to be subjected to an excessive falling load, and stable test data can be obtained, and the life of the rapid loading test apparatus 1 itself can be significantly improved.

  In addition to the above-described case, the present invention can constitute a rapid loading test apparatus that can easily perform a rapid loading test on a pile having a pile diameter of about 1000 mmφ, and a cylinder using air pressure or water pressure in addition to a hydraulic cylinder. It is also possible to adopt a configuration including

1 is a schematic system diagram showing an overall configuration of a rapid loading test apparatus according to an embodiment of the present invention. It is a top view which shows the weight receptacle part in the drop impact load transmission means of the rapid loading test apparatus which concerns on a present Example. It is a hydraulic system figure of the rapid loading test apparatus which concerns on a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pile rapid load test apparatus 2 Drop impact load transmission means 3 Hydraulic shilling 3A Cylinder main body 4 Cylinder rod 5 Cylinder holder 5a Hole 6 Upper hydraulic receptacle 6a O-ring 6b O-ring 6c Ridge part 7 Bolt 8 Weight receiver 9 Suspended body 9a Threaded portion 10 Lower hydraulic receiving body 10a O-ring 11 Upper cylinder chamber 12 Lower cylinder chamber 13 Cover cylinder 14 Buffer 15 Upper port 16 Lower port 20 Hydraulic adjustment means 21 Frame body 22 Base 23 Support column 24 Upper plate 25 Motor 26 High-pressure pump 27 Low-pressure pump 28 Electric hydraulic unit 29 Oil tank 30 Accumulator 31 Check valve 32 4-port switching valve 32A First valve body 32B Second valve body 33 Check valve 34 Relief valve 35 Sequence valve 36 Sequence valve 37 Pressure 38 check valves 41 1st check valve 2 second stop valve 50 piles 51 pile 60 double weight SOLA electromagnetic solenoid SOLB electromagnetic solenoid

Claims (5)

A rapid loading test device for piles that transmits a drop impact load due to the fall of a weight to a pile head and performs a rapid loading test,
A drop impact load transmission means using a hydraulic cylinder that is disposed between the pile head and the weight, receives a drop impact load due to the fall of the weight by the cylinder rod, and transmits it to the pile head through the cylinder rod;
Hydraulic pressure adjusting means for adjusting the transmission force of the impact load from the cylinder rod of the hydraulic cylinder to the pile head, the adjustment of the transmission time by adjusting the hydraulic pressure acting on the cylinder rod;
A rapid loading test apparatus for piles, comprising: A rapid loading test device for piles that transmits a drop impact load due to the fall of a weight to a pile head and performs a rapid loading test,
A pile placed between the head of the pile and the weight and subjected to a drop impact load due to the fall of the weight by a cylinder rod having a weight receiver at the top, through the cylinder rod and a buffer disposed at the bottom thereof. Drop impact load transmission means using a hydraulic cylinder that transmits to the head,
Hydraulic adjustment means for adjusting the transmission force and transmission time of the impact load from the cylinder rod of the hydraulic cylinder to the pile head by adjusting the hydraulic pressure of the oil acting on the cylinder rod;
A rapid loading test apparatus for piles, comprising: A rapid loading test device for piles that transmits a drop impact load due to the fall of a weight to a pile head and performs a rapid loading test,
The cylinder rod placed between the pile head and the weight and receiving a drop impact load due to the fall of the weight by the cylinder rod provided with the weight receiving body using the cushioning material at the top, the buffer arranged at the cylinder rod and the bottom thereof A drop impact load transmission means using a hydraulic cylinder that transmits to the pile head via a shock absorber using a material;
Adjustment of the transmission force and transmission time of the impact load from the cylinder rod of the hydraulic cylinder to the pile head, the supply of oil with a predetermined hydraulic pressure to the first and second cylinder chambers of the hydraulic cylinder and the first and second Hydraulic pressure adjustment means by receiving the discharge oil from the cylinder chamber,
A rapid loading test apparatus for piles, comprising:   The rapid loading test apparatus for piles according to any one of claims 1 to 3, wherein the drop impact load transmitting means includes a vertical settlement guide mechanism for guiding vertical settlement of a cylinder rod when a weight is dropped.   The rapid loading test apparatus for a pile according to any one of claims 1 to 4, wherein a transmission time of the impact load to the pile head can be set to 0.05 to 0.2 seconds.

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