JP5522676B2 - Ground anchor tension device - Google Patents

Description

  The present invention relates to a technique for managing tension work of a ground anchor. More specifically, the present invention relates to a technique for increasing or decreasing the fluid pressure of a working fluid (for example, pressure oil) supplied to a jack used in a tensioning operation of a ground anchor at a predetermined speed.

As an operation for applying the above technique, for example, a lift-off test of an existing anchor is known. The lift-off test is a test for measuring the tension acting on an existing ground anchor at the present time (at the time of the lift-off test), and thereby examining the soundness of the ground anchor. In the lift-off test, a re-tension force (tensile force) is applied to a tendon (steel wire, steel bar, etc.) of a ground anchor by, for example, a jack, and the displacement of the tendon and the tensile force applied by the jack are measured.
5 to 7 show a jack and other test devices used in the lift-off test, and show the flow of pressure oil supplied to the jack.

In FIG. 5, the lift-off test apparatus has a jack 10, a hydraulic unit 30, and a hydraulic line L. The jack 10 is connected to an anchor head (not shown) of an existing ground anchor.
In the state shown in FIG. 5, no pressure oil is supplied to the jack 10, and the lift-off test is stopped.
If the hydraulic pressure is applied to the right chamber 10b of the jack 10 from the lift-off test stop state shown in FIG. 5 (FIG. 6), the tensile force acting on the ground anchor increases. On the other hand, if hydraulic pressure is applied to the left chamber 10c of the jack 10 (FIG. 7), the tensile force that acts on the ground anchor decreases.

5 to 7, the hydraulic unit 30 includes a flow path switching valve 50, a hydraulic pump 35, a hydraulic pump driving motor 36, a hydraulic oil tank 37, and a hydraulic line L.
The hydraulic line L has lines LA, LB, LC, LD, LE, and LF.
The line LA is provided with a flow rate adjusting valve V1 and communicates the discharge side of the pump 35 and the port 50a of the switching valve 50.
A branch point B is formed in a region between the pump 35 and the flow rate adjusting valve V1 in the line LA.
The line LB communicates with the port 50 b of the switching valve 50 and the right chamber 10 b of the jack 10.

The line LC communicates the left chamber 10 c of the jack 10 and the port 50 c of the switching valve 50.
The line LD is provided with a step-down valve V2 and communicates the port 50d of the switching valve 50 and the hydraulic oil tank 37.
The line LE communicates the branch point B and the hydraulic oil tank 37 with a relief valve V3.

When performing the lift-off test, first, as shown in FIG. 6, the jack 10 applies a force (tensile force) in a direction of pulling up to the ground side as a re-tension force with respect to the ground anchor.
In FIG. 6, by applying hydraulic pressure to the right chamber 10b of the jack 10 and moving the piston rod 10R to the left in FIG. 6, the tendon engaged with the piston rod 10R via the engaging means (not shown) is used. To apply a tensile force.
At this time, if excessive hydraulic pressure acts on the right chamber 10b of the jack 10, a part of the hydraulic oil (pressure oil) flowing through the lines LA and LB is supplied to the hydraulic oil via the relief valve V3 and the line LE. Return to tank 37.

When the amount of pressure oil supplied to the right chamber 10b of the jack 10 is increased, the tendon is eventually displaced by the re-tensioning force, and the anchor plate is lifted. Immediately before the anchor plate is lifted, the tensile force by the jack 10 and the tension at the present moment of the tendon (at the time of the lift-off test) are balanced.
In the lift-off test, the tension of the tendon at the present time (the time of the lift-off test) is determined by measuring the tensile force of the jack in such a state, thereby determining the soundness of the ground anchor.

FIG. 8 shows an example of the result of the lift-off test.
FIG. 8 shows the relationship (characteristic) between the tensile force applied by the jack (vertical axis in FIG. 8: load) and the amount of tendon displacement at that time.
The lift-off test result is theoretically as shown by a characteristic line A (two-dot chain line) in FIG. That is, in the example of FIG. 8, in the region where the tensile force of the jack is smaller than the tension of the tendon (region where the load is up to 150 kN), the tendon is not displaced, and only the tensile force (load) by the jack is along the vertical axis. To increase.
Theoretically, in the region where the tensile force of the jack is larger than the tensile force of the tendon (the region where the load is larger than 150 kN), the displacement of the tendon and the tensile force of the jack are in a proportional relationship.

Here, due to the effects of the tendon and other members of the ground anchor and the shrinkage of the members of the jack 10, the result of the actual lift-off test is as shown by a characteristic line B (dotted line having a plot) in FIG.
In the characteristic line B, a region indicated by symbol Ba is a region where the tensile force of the jack exceeds the tension of the tendon.

The point P1 in the area Ba is an inflection point due to a change in the gradient of the characteristic line B in the vicinity thereof.
In the region where the tensile force by the jack is larger than the point P1 (in FIG. 8, the upper side of the point P1), the amount of tendon displacement relative to the tensile force (load) by the jack is large.
Here, the point P1 is referred to as a “lift-off point”, and the tensile force (load) due to the jack at the point P1 is referred to as a “lift-off load”. The lift-off test can be said to be a test for determining the “lift-off point”.
As described above, in the lift-off test, the lift-off point (point P1) or the lift-off load (load at the point P1) is obtained, and the soundness of the ground anchor is determined.

After applying a load larger than the lift-off load to the tendon, as shown in FIG. 7, the hydraulic pressure is supplied to the left chamber 10c to reduce the tensile force (load) due to the jack.
In FIG. 8, a region indicated by reference sign Bb is a region where the tensile force (load) due to the jack decreases.
Here, in the characteristic line B of the actual lift-off test result shown in FIG. 8, the region Bb shows the hysteresis characteristic.

When carrying out the lift-off test as described above, it is required as a “reference” for the lift-off test that the force for pulling up the ground anchor, that is, the tensile force by the jack 10 is increased at a constant rate.
And since the tensile force by the jack 10 is proportional to the pressure in the right chamber 10b of the jack 10, increasing the tensile force by the jack 10 at a constant rate makes the pressure increase rate in the right chamber 10b of the jack 10 constant. It is synonymous with doing. In other words, as a “reference” for the lift-off test, it is required to increase the pressure in the right chamber 10b of the jack 10 at a certain rate.
However, in the conventional lift-off test apparatus shown in FIGS. 5 to 7, increasing the tensile force by the jack 10 at a constant rate, or increasing the pressure in the right chamber 10 b of the jack 10 at a constant rate, It was extremely difficult.

In FIG. 9, the vertical axis indicates the tensile force or load by the jack 10, and the horizontal axis indicates the passage of time when the tensile force or load is applied by the jack 10.
When the lift-off test is performed, it is required as a “reference” to apply a tensile force or a load by the jack 10 with a linear characteristic as indicated by a symbol Lc in FIG.
However, as described above, it is extremely difficult to increase the tensile force by the jack 10 at a certain rate in the conventional technique. In the prior art, the tensile force by the jack 10 increases stepwise every 10 to 20 kN, as indicated by the symbol Lp in FIG.
When the lift-off test is performed according to the conventional technique, the measurement is performed at predetermined time intervals (t1, t2, and t3 in FIG. 9). For example, when the lift-off point P1 exists in a region (range Δ) between the measurement point measured at time t2 and the measurement point measured at time t3, the accurate numerical value of the lift-off point P1 is grasped. I can't do that.

In the prior art shown in FIGS. 5 to 7, in order to prevent the tensile force from changing stepwise like the characteristic Lp in FIG. 9, the rotational speed of the pump drive motor 36 is controlled using an inverter 38, for example. Thus, it is conceivable to increase the pressure in the right chamber 10b of the jack 10 at a constant rate or speed.
However, fine control such as a lift-off test is extremely difficult in the control based on the rotational speed of the drive motor.

Alternatively, in the prior art shown in FIGS. 5 to 7, in order to increase the pressure in the right chamber 10b of the jack 10 at a constant rate or speed, the relief valve V3 and / or the flow rate adjustment valve V1 are opened and closed in small increments. It is conceivable to control the opening and closing so that it can be considered that the pressure is constantly increased when observed macroscopically.
However, controlling the amount of hydraulic pressure supplied to the right chamber 10b of the jack 10 so that it can be considered that the pressure is constantly increased when viewed macroscopically requires very delicate control. Implementation requires enormous costs.

As a “reference” for the lift-off test described above, it is required to reduce the tensile force by the jack 10 at a constant rate, in other words, to lower (depressurize) the pressure of the pressure supply line L at a constant rate (speed). Is done.
However, reducing the pressure in the pressure supply line L at a constant speed is more difficult to control than in the case of boosting.
The problem that it is difficult to increase and decrease the tensile force by the jack at a certain rate exists not only in the lift-off test but also in fixing the ground anchor.

As another conventional technique, a technique has been proposed in which a sensor plate is provided and the relationship between a load acting on the sensor plate and a compressive strain is obtained, and thus the tension of tendon is detected (Technical Document 1).
However, in the related art, the tension of the tendon is detected by obtaining the compressive strain of the sensor plate, and the pressure of the pressure oil as the working fluid cannot be increased or decreased at a constant speed in the lift-off test.

JP 2008-70205 A

 The present invention has been proposed in view of the above-mentioned problems of the prior art, and arbitrarily controls the pressure increase / decrease speed of the working fluid in the pressure supply line for supplying the pressure oil to the jack cylinder in the tension work of the ground anchor. The purpose is to provide a ground anchor tensioning device that can be used.

According to the present invention, the jack (1) for imparting tension to the ground anchor, the displacement amount measuring device for measuring the displacement of the tendon (A) of the ground anchor (2), the jack (1 ) and hydraulic fluid supply device for supplying a working fluid to (3), and a said hydraulic fluid supply device (3) and the jack (1) and the communication with the working fluid flows through hydraulic fluid line (L), wherein the fluid pressure measuring device for measuring the fluid pressure of the hydraulic fluid line hydraulic fluid supplied (L) a flow spent by hydraulic fluid supply device (3) to the jack (1) (4), the working fluid line ( a portion of the working fluid flowing through L) a relief circuit (relief valve (52 to return to the hydraulic fluid supply device via Lr) (3)), switching the flow of hydraulic fluid through said hydraulic fluid line (L), jack me more than ( In tensioning device of the ground anchor and a driving switching device (51) for switching the operation), in response to a signal color the displacement amount measuring device and (2) the fluid pressure measuring device (4), said relief circuit with the control device for adjusting the increase or decrease of the degree of opening of the port (52r) communicating with (Lr) side and (6), wherein the control device (6) is a jack (1) a fluid pressure measuring device when boosting (4) In response to the measurement result of the above , the function of controlling the pressure fluctuation speed of the fluid pressure of the working fluid supplied from the working fluid supply device (3) to the jack (1) to an arbitrary speed, and the control device ( 6) The pressure measured at each control interval by the fluid pressure measuring device (4) is stored in the database (65) (S1), and {(current pressure) − (previous pressure) / (control interval)} Calculate and on pressure It is determined whether the rate is equal to the target value (S2). If the rate of pressure increase is equal to the target value, the port opening to the relief side is left as it is (S3), and the rate of pressure increase exceeds the target value. If so, the opening degree of the port toward the relief side is increased (S4), and if the rate of pressure increase is less than the target value, the opening degree of the port toward the relief side is decreased (S5) .

  According to the present invention having the above-described configuration, the operation is performed in accordance with the operation of the jack (1) (the pressure of the jack, the pressure of the jack, the stop of the jack) based on the measurement result of the fluid pressure measuring device (4). Since the pressure fluctuation speed in the fluid line (L) can be controlled arbitrarily (in other words, the pressure fluctuation speed can be adjusted to be within a predetermined allowable range with respect to the reference speed), for example, the tensioning device is lifted off. In the case of the test apparatus, the ground anchor lift-off test can be easily and safely performed according to a predetermined standard.

Specifically, when the pressure of the jack (1) is increased, if the pressure fluctuation speed (pressure increase speed) in the working fluid line (L) is faster than the reference speed of the lift-off test, the relief valve (proportional electromagnetic relief valve 52, valve The opening of the port communicating with the relief circuit (Lr) side of the relief part 52) in the unit 5 is increased, and the working fluid flowing through the working fluid line (L) is supplied to the working fluid supply device (Lr) via the relief circuit (Lr). Increase the amount returned to 3).
By increasing the opening degree of the port communicating with the relief valve (52) on the relief circuit (Lr) side, the amount returned to the working fluid supply device (3) via the relief circuit (Lr) is increased, and the jack Reduce the flow rate of the working fluid supplied to (1).
As a result, the pressure of the working fluid in the working fluid line (L) communicating with the jack (1) can easily escape to the relief circuit (Lr) side, and the pressure of the working fluid in the working fluid line (L) is difficult to increase. The pressure increase speed of the jack (1) becomes slow.

On the other hand, when the pressure increase speed in the working fluid line (L) is slower than the reference speed of the lift-off test, the opening degree of the port communicating with the relief circuit (Lr) side of the relief valve (52) is decreased, and the relief circuit (Lr ) To reduce the flow rate of the working fluid that returns to the working fluid supply device (3).
As a result, it becomes difficult for the pressure of the working fluid in the working fluid line (L) communicating with the jack (1) to escape to the relief circuit (Lr) side, and the pressure of the working fluid in the working fluid line (L) easily rises. The pressure increase speed of the jack (1) is increased.

When lowering the speed of the jack (1), if the pressure reduction speed is high, the opening degree of the port communicating with the relief circuit (Lr) side of the relief valve (52) is reduced, and the working fluid supply device is connected via the relief circuit (Lr). Reduce the flow rate of the working fluid that returns to (3). This makes it difficult for the working fluid flowing from the jack (1) to the working fluid line (L) to flow, and makes it difficult to reduce the pressure of the working fluid in the working fluid line (L). Slow down the descent speed.
On the other hand, when the step-down speed is slow, the opening degree of the port communicating with the relief circuit (Lr) side of the relief valve (52) is increased, and the working fluid flowing from the jack (1) to the working fluid line (L) flows. Make it easier. As a result, the pressure of the working fluid in the working fluid line (L) tends to decrease, and the pressure drop speed of the jack (1) increases.

As a result, it is possible to achieve high-precision pressure fluctuation when the jack (1) is stepped down, which was difficult in the prior art, and to realize smooth control characteristics close to the reference (or target) in the lift-off test. is there.
Here, there are cases where it is easier to evaluate the soundness of a ground anchor made of, for example, a steel wire (determinable by the elastic coefficient of the ground anchor) using data at the time of jack pressure reduction.

  Here, according to the present invention, the fluid pressure of the working fluid supplied from the working fluid supply device (3) to the jack (1) is directly measured by the fluid pressure measuring device (4). Compared with the case where the supply pressure to the jack (1) is converted by measuring the strain of the jack (1), the pressure fluctuation of the jack (1) is directly obtained, and the control with higher accuracy can be executed accordingly.

It is a block diagram of a 1st embodiment of the present invention. It is a flowchart which shows control of 1st Embodiment. It is a block diagram of a 2nd embodiment of the present invention. It is a block diagram of a 3rd embodiment of the present invention. It is the block diagram which showed the structure of the lift-off test apparatus of the ground anchor concerning a prior art, Comprising: It is a figure which shows the state which stopped the lift-off test. FIG. 6 is a block diagram similar to FIG. 5, showing a state where the jack is boosted in a lift-off test. It is a block diagram similar to FIG. 5, FIG. 6, Comprising: It is a figure which shows the state which pressure | voltage-falls a jack by a lift-off test. It is a characteristic view which shows the relationship between the tensile force (load) by a jack at the time of implementing a lift-off test, and the displacement in a ground anchor. FIG. 9 is a diagram illustrating the characteristic diagram of FIG. 8 in a simplified manner and a part of the characteristic during boosting in a microscopic manner.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
Here, since the main use purpose of the tensioning device of the present invention is the lift-off test of the existing anchor, the embodiment shown in the drawings will be described for the case where it is applied to the lift-off test. However, the tensioning device of the present invention can be effectively used for a newly-installed ground anchor as in the lift-off test of an existing anchor.
First, the first embodiment will be described with reference to FIGS.
In FIG. 1, a ground anchor tensioning device (lift-off test device) denoted as a whole by 101 is a jack 1, a displacement meter 2, a working fluid supply device 3, a pressure sensor 4, a valve unit 5, a control device 6, and a hydraulic line. L.

The working fluid supply device (oil pump unit) 3 includes an oil pump 31, a working oil tank 32, and a hydraulic shortcut circuit 33.
The hydraulic shortcut circuit 33 has a built-in circuit for returning the pressure oil boosted by the oil pump 31 to the hydraulic oil tank 32 when it is not necessary to send hydraulic pressure to the jack 1 during the lift-off test.
The hydraulic shortcut circuit 33 can be omitted.

The valve unit 5 includes a direction switching valve (for example, a 4-port electromagnetic pilot valve) 51 and a relief valve (for example, a proportional electromagnetic relief valve) 52.
The pressure sensor 4 is built in the valve unit 5. However, the pressure sensor 4 can be provided outside the valve unit 5. The pressure sensor 4 measures the hydraulic pressure of hydraulic fluid that flows through the line L2. The input signal line Si4 is connected to the control unit 60.

The control device 6 includes a control unit 60 and a database 65 as storage means.
The direction switching valve 51 is configured to switch between pressure increase, pressure reduction, and stop by switching the flow path. As the direction switching valve 51, a publicly known or commercially available one can be applied as it is. A control signal is received from the control unit 60 via the signal line So5.

When switching the pressure increase, pressure reduction, and stop by the direction switching valve 51, when the force (arrow Pu: load by the jack 1) that pulls the tendon A by the jack 1 is increased (pressure increase), as shown by a solid line in FIG. In addition, the port 51a and the port 51b of the direction switching valve 51 are communicated, and the port 51c and the port 51d are communicated.
On the other hand, when the load Pu by the jack 1 is decreased (decrease), the state where the port 51a and the port 51b and the port 51c and the port 51d communicate with each other is initially maintained. Finally, when the cylinder of the jack 1 is completely moved (in the case of FIG. 1, it moves to the right), the port 51a and the port 51c of the direction switching valve 51 are communicated, and the port 51b and the port 51d are connected. (The dotted line in FIG. 1).
When the jack 1 is stopped, any two of the four ports 51a to 51d are closed.

The hydraulic line L includes a line L1, a line L2, a line L3, a line L4, and a line Lr.
The line L1 is provided with a relief valve 52, and connects the discharge port 33o of the hydraulic shortcut circuit 33 of the oil pump unit 3 and the port 51a of the direction switching valve 51.
The line L2 connects the port 51b of the direction switching valve 51 and the inlet / outlet 1a of the jack 1.

The line L3 connects the inlet / outlet 1b of the jack 1 and the port 51c of the direction switching valve 51.
The line L4 connects the port 51d of the direction switching valve 51 and the suction port 33i of the hydraulic shortcut circuit 33.
A merge point G is formed in the line L4.
The junction G and the relief-side port 52r of the relief valve 52 communicate with each other through a relief line Lr. Via this relief line Lr, a part of the pressure oil flowing through the line L1 joins the line L4 and is returned to the hydraulic oil tank 32 without being supplied to the jack 1.

The relief valve 52 is connected to the control unit 60 of the control means 6 by a control line So.
The control unit 60 controls the opening degree of a port (not shown) communicating with the relief line Lr in the relief valve 52, thereby increasing the rate of increase in pressure of the hydraulic oil flowing through the line L2 (pressure increase rate: pressure It has a function to keep the ascending speed) constant.

Specifically, when the rate of pressure increase in the line L2 is fast (large), the opening degree of the port communicating with the relief line Lr in the relief valve 52 increases, and the pressure oil (actuation) that flows from the relief valve 52 to the line Lr side Oil) and the flow rate of the hydraulic oil flowing through the line L2 is decreased.
As a result, the pressure in the working fluid lines L2 and L1 communicating with the jack 1 easily escapes to the relief circuit Lr side, and the lines L2 and L1 are difficult to increase in pressure, so that the pressure increase speed of the jack 1 is reduced.

On the other hand, when the pressure rise in the line L2 is slow (small), the opening degree of the port communicating with the relief line Lr in the relief valve 52 is decreased, and the amount of pressure oil (operating oil) flowing from the relief valve 52 to the line Lr side Decrease. Accordingly, the flow rate of the hydraulic oil flowing through the line L2 is increased.
As a result, the pressure in the working fluid line L communicating with the jack 1 is unlikely to escape to the relief circuit Lr side, so the lines L2 and L1 are likely to increase in pressure, and the rate (speed) of the pressure increase in the line L2 becomes steep ( The pressure increase speed is accelerated).

Here, in the first embodiment, not only when the pressure rises, but also when the pressure drops, the rate of increase in pressure of the hydraulic oil flowing through the line L2 (pressure increase rate: pressure increase rate) is kept constant. It has a function to squeeze.
When the pressure of the jack 1 is lowered, at the initial stage, the port 51a and the port 51b of the direction switching valve 51 communicate with each other, and the state in which the port 51c and the port 51d communicate with each other is maintained. In this state, the hydraulic oil from the jack 1 returns to the hydraulic oil tank 32 via the line L2, the relief circuit Lr, and the line L3.

When the pressure drop speed is high at the time of such pressure drop, the opening degree of the port 52r communicating with the relief circuit Lr side of the relief valve 52 is decreased, and the flow rate of the hydraulic oil flowing through the relief circuit Lr is reduced. As a result, the hydraulic oil that returns from the jack 1 to the hydraulic oil tank 32 via the hydraulic oil line L2, the relief circuit Lr, and the line L3 is difficult to flow, and the pressure of the hydraulic oil in the line L2 is difficult to decrease. As a result, the pressure drop speed in the jack 1 is reduced.
On the other hand, when the step-down speed is slow, the opening degree of the port 52r communicating with the relief circuit Lr side of the relief valve 52 is increased, and the hydraulic oil tank is connected from the jack 1 via the hydraulic oil line L2, the relief circuit Lr, and the line L32. Increase the flow rate of hydraulic fluid back to 32. As a result, the hydraulic oil easily flows from the jack 1 to the line L2, the pressure in the line L2 is easily reduced, and the pressure drop speed of the jack 1 is increased.

The pressure of the jack 1 is sufficiently lowered, and finally the piston (not shown) in the jack 1 is completely moved (in the example of FIG. 1, the piston (not shown) is completely moved right in the cylinder of the jack 1). At this time, the port 51a and the port 51c of the direction switching valve 51 communicate with each other, and the port 51b and the port 51d communicate with each other.
In such a state, the hydraulic oil from the jack 1 returns to the hydraulic oil tank 32 via the line L2, the line L4, and the line L32.

In the first embodiment, a line L1 that escapes to the relief line Lr side by adjusting the opening and closing of the port communicating with the relief line Lr in the relief valve 52 and controlling the flow rate of the hydraulic fluid flowing through the line L2. The pressure of the hydraulic oil flowing through the lines L1 and L2 is controlled to arbitrarily adjust the pressure increase rate (pressure increase rate) or the pressure decrease rate (pressure reduction rate).
And the pressure rise speed and pressure drop speed in the jack 1 can be made constant by arbitrarily adjusting the rate of increase or decrease in the pressure of the hydraulic oil flowing through the lines L1 and L2.

The oil pump unit 3 has internal lines L31, L32, and L33.
The internal line L31 communicates the discharge port 31o of the pump 31 and the hydraulic shortcut circuit 33.
The internal line L32 connects the hydraulic shortcut circuit 33 and the hydraulic oil tank 32.
The internal line L33 communicates the hydraulic oil tank 32 and the suction port 31i of the oil pump 31.

Here, the displacement meter 2 that measures the tendon displacement is connected to the control unit 60 of the control device 6 by the input signal line Si2.
The displacement meter 2 measures the displacement of the tendon by measuring the movement of the cylinder portion of the jack 1 and a member (not shown) pulled by the jack 1 by engaging with the tendon in the head portion of the ground anchor. It is configured to measure.

Next, based on the flowchart of FIG. 2, the control of the lift-off test apparatus 101 will be described with reference to FIG. Here, in FIG. 2, the control at the time of a pressure rise is shown.
In step S1 of FIG. 2, the pressure sensor 4 measures the pressure in the line L2 at each control interval. The measured value (pressure in the line L2) is stored in the database 65 of the control device 6.

In step S2, the control unit 60 obtains the measured value of the sensor 4 in the previous control cycle (measured value stored in the database 65) from the measured value of the pressure sensor 4 in the current control cycle (latest measured value). Subtract. Then, the subtracted value is divided by the time interval (that is, the control interval) of the control cycle. That is, in step S2,
(Current pressure)-(Previous pressure) / (Control interval)
Is calculated.
Here, “(current pressure) − (previous pressure) / (control interval)” indicates the pressure increase rate of the line L2.
Then, it is determined whether or not the calculated pressure increase rate of the line L2 is equal to the target value.

Here, since the time interval (that is, the control interval) of the control cycle is determined for each test apparatus (is a constant), “(current pressure) − (previous pressure)” is the pressure of the line L2. Corresponds to the rate of increase.
Therefore, in step S2, it may be determined whether “(current pressure) − (previous pressure)” is equal to the target value.

When the pressure increase rate of the line L2 is equal to the target value (step S2 is YES), the process proceeds to step S3.
On the other hand, if the pressure increase rate of the line L2 exceeds the target value, the process proceeds to step S4.
If the rate of pressure increase in the line L2 is less than the target value, the process proceeds to step S5.

In step S3 (when the pressure increase rate of the line L2 is equal to the target value), the opening degree (the opening degree to the relief side) of the port (not shown) communicating with the line Lr side in the relief valve 52 is maintained as it is. Step S1 and subsequent steps are repeated again.
In step S4 where the pressure increase rate of the line L2 exceeds the target value, the control unit 60 controls the relief valve 53 so as to increase the opening of the port communicating with the relief line Lr. Then, step S1 and subsequent steps are repeated again.
By increasing the opening degree of the port communicating with the relief line Lr side, as described above, the flow rate of the pressure oil (hydraulic oil) flowing through the line L2 is reduced, and the pressures of the lines L1 and L2 are reduced to the relief line Lr side. It becomes easy to escape and the pressure of the line L1 and the line L2 becomes difficult to raise. Thereby, the pressure | voltage rise speed (ratio, ratio) of the jack 1 is decelerated.

In step S5 in which the pressure increase rate of the line L2 is less than the target value, the control unit 60 controls the relief valve 53 so as to decrease the opening degree of the port communicating with the relief line Lr, and then repeats step S1 and subsequent steps. repeat.
By reducing the opening degree of the port communicating with the relief line Lr, the flow rate of hydraulic oil in the line L2 increases, and the pressure in the lines L1 and L2 becomes difficult to escape to the relief line Lr, and the lines L1 and L2 The pressure of is likely to rise. Thereby, the boosting of the jack 1 is accelerated.

As described above, according to the first embodiment, since the pressure in the line L2 is controlled to fluctuate at a constant speed based on the measurement result of the pressure sensor 4, the lift-off test is performed according to a predetermined standard. Can be executed easily and safely.
In the lift-off test, there is also a “reference” for the reduction of the tensile force (load) acting on the ground anchor by the jack 1, that is, the speed of pressure reduction of the line L1. For example, in the first embodiment, the rate of pressure reduction is twice (constant) the rate of pressure increase.

Next, a second embodiment of the present invention will be described with reference to FIG.
In FIG. 3, the tensioning device (lift-off test device) generally indicated by reference numeral 102 is different in the configuration of the control device 6 </ b> A from the lift-off test device 101 (FIG. 1) of the first embodiment.
The control device 6 </ b> A of the lift-off test device 102 according to the second embodiment includes a control unit 60 and an integration circuit 67. Similarly to the control unit 60, the integrating circuit 67 is also connected to the pressure sensor 4 by the input signal line Si4.
The signal input to the control unit 60 by the integrating circuit 67 is delayed by one control cycle.

The control of the second embodiment is performed similarly to the control flowchart of FIG.
In the first embodiment, the measurement value (measurement value of the pressure sensor 4) in the previous control cycle stored in the database 65 is used in the calculation of step S2. On the other hand, in the second embodiment, the measurement value delayed by one control cycle by the integration circuit 67 (measurement value of the pressure sensor 4 in the previous control cycle) and the measurement value not passed through the integration circuit 67 (current time) The measurement value of the pressure sensor 4 in the control cycle) data (pressure value) is integrated, and the calculation of step S2 is executed.

According to the second embodiment, by operating the integration circuit 67, control having smooth control characteristics becomes possible. The control characteristics can be made closer to the lift-off test standard (target control characteristics).
In the second embodiment, the control cycle delayed by the integration circuit 67 is not only delayed by one cycle and integrated by two cycles, but also delayed by two or more control cycles and by three or more control cycles. It is also possible to integrate.
Other configurations and operational effects in the second embodiment are the same as those in the first embodiment.

A third embodiment will be described with reference to FIG.
In FIG. 4, a tensioning device (lift-off test device) generally indicated by reference numeral 103 includes a jack 1, a pair of displacement meters 21, 22, a hydraulic unit 3, a pressure sensor 4, a valve unit 5A, and a control device 6B. Yes.

The hydraulic unit 3 shown in FIG. 4 is depicted to have a different shape from the hydraulic unit 3 of FIGS. 1 and 3, but basically the hydraulic unit 3 of FIGS. 1, 3, and 4 is the same. It is a simple configuration.
In the first embodiment and the second embodiment, the valve unit 5 is a unit in which the direction switching valve (4-port electromagnetic pilot valve) 51 and the relief valve (proportional electromagnetic relief valve) 52 are separate units.
On the other hand, in the valve unit 5A of the third embodiment, a proportional electromagnetic relief valve and a 4-port electromagnetic pilot valve are integrated.
However, regarding the relief function, the valve unit 5A of the third embodiment and the relief valve 52 of the valve unit 5 of the first and second embodiments are the same.

 In FIG. 4, the pressure sensor 4 is interposed outside the valve unit 5A, that is, immediately before the jack 1. However, the pressure sensor 4 can be built in the valve unit 5A.

The control device 6B includes a personal computer 61 that also serves as input, calculation, and storage means, and a lift-off management device main body 62.
The displacement meter 21 is connected to the lift-off management device main body 62 by an input signal line Si21, and the displacement meter 22 is connected to the lift-off management device main body 62 by an input signal line Si22. The valve unit 5A is connected to the lift-off management device main body 62 by a control signal line So.
Although not shown, it is also possible to apply the control device 6B of FIG. 4 to the first embodiment and the second embodiment.

 Other configurations, controls, and effects of the third embodiment are the same as those of the first and second embodiments.

The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
For example, although the illustrated embodiment has been described only for ground anchor lift-off testing, the present invention can be applied in checking tendon tension when fixing a ground anchor.

DESCRIPTION OF SYMBOLS 1 ... Jack 2 ... Displacement meter 3 ... Hydraulic unit 4 ... Pressure sensor 5, 5A ... Valve unit 6, 6A, 6B ... Control apparatus 31 ... Hydraulic pump 32 ... Hydraulic oil tank 33 ... Hydraulic shortcut circuit 51 ... Direction switching valve / 4 port electromagnetic pilot valve 52 ... Relief valve / Proportional electromagnetic relief valve 60 ... Control unit 65 ... Storage means / database 67... Integration circuit

Claims (1)

Supplied jack (1) for imparting tension to the ground anchor, the displacement amount measuring device for measuring the displacement of the tendon (A) of the ground anchor (2), the working fluid said to jack (1) hydraulic fluid supply device (3) and which comprises said hydraulic fluid supply device (3) and the jack (1) and the communication with the working fluid flows through hydraulic fluid line (L), the working fluid line (L ) and the flow spent by the fluid pressure measuring device for measuring the fluid pressure of the hydraulic fluid supplied from the hydraulic fluid supply device (3) to the jack (1) (4), the working fluid flowing in the hydraulic fluid line (L) The relief valve (52) that returns a part of the working fluid to the working fluid supply device (3) via the relief circuit (Lr) and the flow of the working fluid that flows through the working fluid line (L) are switched, whereby the jack (1 Turn off the operation of) In tensioning device of the ground anchor and a obtain operation changeover device (51) receives a signal color the displacement amount measuring device and (2) the fluid pressure measuring device (4), said relief circuit (Lr) side and a control device for adjusting the increase or decrease of the degree of opening of the port (52r) communicating (6), the control device (6) is the measurement result of the fluid pressure measuring device when the boosting of the jack (1) (4) In response, the control device (6) has a function of controlling the pressure fluctuation speed of the fluid pressure of the working fluid supplied from the working fluid supply device (3) to the jack (1) to an arbitrary speed. The pressure measured at the control interval by the pressure measuring device (4) is stored in the database (65) (S1), {(current pressure) − (previous pressure) / (control interval)} is calculated, and the pressure is calculated. The rate of increase is equal to the target value When the pressure increase rate is equal to the target value, the opening degree of the port to the relief side is left as it is (S3), and if the pressure increase rate exceeds the target value, the relief side For increasing the opening of the port to the ground (S4), and reducing the opening of the port to the relief side if the rate of pressure increase is less than the target value (S5) . apparatus.

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