JPS5829379B2 - pile hammer - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in pile hammers.

Conventionally, diesel pile hammers have been widely used for driving piles in civil engineering works, etc. for hard ground, and vibrating pile drivers for soft ground. Since the combustion explosion is performed and the recoil is used to drive the pile, the explosion noise is very loud, and the explosion state of the fuel changes depending on the ground conditions, making it difficult to achieve a complete and ideal combustion. This produces black smoke or exhaust gas, which causes environmental pollution, making it particularly difficult to use in urban areas.

On the other hand, in the case of a vibratory pile driver, the vibration is so intense that the ground vibrates as if a weak earthquake had occurred, which not only causes material damage to neighboring houses but also avoids discomfort to neighboring residents. However, its use for this purpose has recently been subject to significant restrictions from the standpoint of pollution prevention.

As described above, the use of conventional pile hammers in urban areas is restricted due to environmental pollution issues, and the industry is demanding the emergence of pile hammers that do not emit exhaust gases and have low noise and vibration. ing.

The present invention was proposed for the purpose of providing a pile hammer capable of meeting the needs of the related industry. an inner cylinder whose lower end opening is fluid-tightly fixed to the periphery of the upper end of the valve port of the bottom cylinder; A pump whose side is fixed, an electric motor fixed to the other side of the pump's casing, and a spiral spiral along the vertical direction within the annular space formed between the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder. a fluid conduit which is arranged in a shape and has an upper end opening connected to the discharge pipe of the pump and a lower end opening connected to the valve chamber of the bottom cylinder; a plunger installed in the bottom cylinder; An opening and closing valve disposed within the valve chamber and normally biased to close the valve port, and in the fluid conduit, configured to open the valve port when the pump output is low and the discharge pressure is high. In order to fill the valve, the inner pipe, and the fluid conduit with fluid and maintain a predetermined pressure, the pile is characterized by being equipped with a member for filling fluid and gas before operation.
This is related to the market.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the attached drawings. In the figure, 1 indicates an outer cylinder having cooling fins 1a on the outer periphery, and 2 indicates a fluid-tight opening at the lower end of the outer cylinder 1. A bottom cylinder is fixed concentrically to the lower end of the outer cylinder 1 so as to be closed, and a plunger 3 for driving the pile P is fitted into the cylinder 2 via a cylinder cover 4.

Further, in the upper part of the cylinder 2, a valve chamber 14ab, a valve seat 14b, and a valve port 14c of an on-off valve 14, which will be described later, are provided.

5 is an inner cylinder arranged concentrically within the outer cylinder 1;
An annular space 6 is provided between the outer peripheral surface of the inner cylinder 5 and the inner peripheral surface of the outer cylinder.
The lower end opening of the inner cylinder 5 is fluid-tightly fixed to the upper peripheral edge of the valve port 14c of the cylinder 2.

Reference numeral 7 denotes a pump with one side of the casing fixed on the peripheral edge of the upper end opening of the inner cylinder 5, and the suction port of the pump 7 is connected to the inner cylinder 5.
A driving electric motor 8 was fixedly connected to the upper end opening on the other end of the casing of the pump 7, and the pump 7 was driven and rotated by the electric motor 8. There is.

The type of pump 7 in the embodiment is a centrifugal pump, and when the discharge amount is small, this type of pump has a high discharge pressure.
Further, when the discharge amount is large, the discharge pressure is low.

Reference numeral 9 denotes a pump discharge pipe having one end connected to the discharge port of the pump 7, and reference numeral 10 denotes a pump discharge pipe arranged spirally from the upper end to the lower end within the annular space 6 between the inner cylinder 5 and the outer cylinder 1. In the fluid conduit,
The upper end opening of the fluid conduit 10 is connected to the other end of the pump discharge pipe 9, and the lower end opening thereof is connected to the on-off valve 14 of the cylinder 2.
It communicates with the inside of the valve chamber 14a.

The total length of the flow path of this fluid conduit 10 is normally set to a length of 20,750 m.

11 is an accumulator fixed to the casing of the electric motor 8, 12 is a liquid level gauge attached to the accumulator 11 as shown in the figure, and 13 is a fluid from the fluid supply port 11a at the upper end of the accumulator 11 and a fluid inside the accumulator 11. The valve 11b for opening and closing the flow is a communication pipe whose upper end is communicated with the lower end of the accumulator 11 and whose lower end is communicated with the upper end of the outer cylinder 1. Beforehand, a relatively low viscosity fluid is filled from the fluid supply port 11a at the upper end of the accumulator 11 with the liquid level meter 12 detecting the liquid level, and then gas is filled and an appropriate addition is made. Pressure state.

For this purpose, the accumulator 11 is provided with a fluid supply port 11ah and a valve 13.

An appropriate pressurized state means that the bottom cylinder 2 is in contact with the top surface of the plunger 3 due to the weight of the entire pile hammer, but it does not separate when the on-off valve 14 is open and the pump 7 is operated. Apply as high pressure as possible within range.

The upper end of the rod 15, whose lower end is attached to the upper surface of the on-off valve 14 which is disposed in the valve chamber 14a of the cylinder 2 so as to be movable up and down, is attached to the inner wall of the inner cylinder 5 at a suitable position in the lower part of the inner cylinder 5. The rod 15 extends upwardly through a cylinder 16 supported concentrically with the inner cylinder 5, and a piston 15a that fits into the cylinder 16 is provided at a proper position on the rod 15.

Reference numeral 17 denotes a compression spring interposed between the lower surface of the piston 15a and the lower peripheral edge of the cylinder 16. When the discharge pressure of the pump 7 is acting on the upper surface of the piston 15a, the spring 17 acts on the discharge pressure. The piston 15a is always energized so as to overcome the pressure and push the piston 15a upward, thereby closing the on-off valve 14.

Reference numeral 18 denotes a discharge pressure guiding hole of the pump 7 to the upper surface of the piston 15a. The pressure guiding hole 18 is provided in the bracket 1b, and connects the appropriate position of the fluid conduit 10 and the space on the upper surface side of the piston 15a of the cylinder 16. It's communicating.

In the embodiment shown in the figure, an annular space 6 formed by an outer cylinder 1 and an inner cylinder 5
It communicates with the discharge port of the pump 7, ie, the inlet of the fluid conduit 100, through the pump 7.

The diameter d of the piston 15a is made larger than the effective diameter dV that determines the effective pressure receiving area of the on-off valve 14, and when the discharge pressure of the pump 7 becomes higher than a predetermined value, the force due to the pressure acting on the upper surface of the piston 15a is The force is greater than the force due to the pressure acting on the lower surface of the on-off valve 14, so that the on-off valve 14 opens.

19 is inner cylinder 5Ji? The manual operation rod of the on-off valve 14 is installed so that it horizontally penetrates the appropriate position of the outer cylinder 1 in a fluid-tight manner, and its inner end is positioned on the axis of the inner cylinder 5. A connecting rod 20 is connected with a pin between the extending end of the rod 15 and has a button, and by operating the operating rod 19 by an appropriate means, the on-off valve 14 can be opened and closed manually. There is.

The pile hammer of the present invention is configured as described above and has a button,
When driving a pile P using this pile hammer, first, temporarily fix one end of the pile P to the lower end of the plunger 3, lift it up via the Ipol 8a with a lifting device such as a mobile crane, and then drive the pile P into the desired position. After lowering it to the position, the electric motor 8 is activated to drive and rotate the pump 7.

In this case, the pressure in the discharge pipe 9 of the pump 7 is equal to the pressure in the fluid conduit 1
It acts on the inner button 0 and the annular space 6, that is, on the outside of the fluid conduit 10.

Since the outside of the fluid conduit 10 is a closed circuit in the area of the bottom cylinder 2, the pressure is almost equal to the discharge pressure of the pump 7.

Furthermore, the flow of fluid discharged from the discharge pipe 9 of the pump 7 is as follows:
A fluid circuit is formed of pump discharge pipe 9 → spiral fluid conduit 10 → valve chamber 14a → valve chamber 14c → inner cylinder 5 → pump suction chamber → pump T → pump discharge tube 9, but before operation of pump 7,
The on-off valve 14 is closed by the compression spring 17 and clicks, and when the pump 7 starts operating in this state, the pump 7 enters the shut-off operation state, and its discharge pressure becomes high, causing the upper surface of the piston 15a and the on-off valve 14 to be pressed. Due to the difference created by the fluid pressure acting on the lower surface, the on-off valve 14 is opened and the flow rate of the fluid in the fluid conduit 10 increases over time and becomes faster.

At this time, the discharge pressure of the pump 7 decreases as the flow rate increases, so the difference in force between the pressure acting on the piston 15a and the pressure acting on the lower surface of the on-off valve 14 is due to the force of the compression spring 17 rather than the pressure. becomes stronger, and the on-off valve 14 is closed.

The on-off valve 14 is closed. To explain this in more detail, Fig. 2 shows the relationship between the pump discharge amount and the discharge pressure.
4 is closed, the discharge amount is zero, and the discharge pressure of Pongoo is the highest, which is at point A in Figure 2.

As mentioned above, since the discharge pressure Pd of the pump 7 acts on the upper surface of the piston 15a, the force F1 here is as follows.

On the other hand, the upward force F2 from below the on-off valve 14 can be similarly expressed as , since the pressure loss in the fluid conduit 10 can be almost ignored.

The force F of the compression spring 17 acts on the on-off valve 14, and the condition for opening the on-off valve 14 is the discharge pressure P, as shown in Figure 2.
When d is larger than the Pm line indicated by . . . , the on-off valve 14 opens.

Therefore, almost simultaneously with pump 7 operating, on-off valve 1
4 becomes open.

When the discharge pressure Pd is large, the pump discharge amount Q
Since almost all of the discharge amount Q of the pump 7 flows through the fluid conduit 10, the flow velocity within the fluid conduit 10 is also low.

The on-off valve 14 is opened, and the discharge amount of the pump 7 gradually increases, reaching from point A to point B.

When reaching point B, the on-off valve 1 is closed due to the balance of forces as described above.
4 is closed.

Therefore, the flow of fluid in the fluid conduit 10 suddenly stops at the opening/closing valve 14.
As a result, the fluid in the fluid conduit 10 generates a so-called water hammer effect based on its inertia, and the upstream side (lower side) of the on-off valve 14 has a rate of 1/cr/l in the range of 100 to 200. A huge amount of pressure is generated instantly.

The mechanism of pressure generation will be explained in more detail.

FIG. 3 shows a model of the pile of the present application.

The buttons in the figure and the parts numbers are the same as in Figure 1.

Although the fluid conduit 10 is shown as a straight pipe for convenience, it is assumed that the length t is as long as 20 to 50 m.

Let its cross-sectional area be a.

It is also assumed that the inner cylinder 5 has a short length and a large cross-sectional area a', and the inertial force of the fluid therein can be ignored.

When high pressure is generated within the cylinder 2, the cylinder 2 and the fluid conduit 10 undergo elastic deformation, resulting in a slightly larger volume, and the fluid here is also compressed, resulting in a slightly smaller volume, but this will simplify the calculation. Therefore, it is assumed that the fluid in the fluid conduit 10 is incompressible, and that the fluid in the cylinder 2 is compressed.

However, at this time, the volume of the cylinder 2 is the fluid conduit 1
Consider an equivalent volume Ve that is 1/2 of the volume of 0.

1. Find the penetration force of this pile hammer when the penetration resistance of the pile is infinite.

Euler's equation for an incompressible fluid is expressed as follows, where u1 is the flow velocity in the fluid conduit 10, t is the fluid density, and ρ is the density of the fluid.

In addition to this, regarding the length direction X of the fluid conduit 10, x = l
'! It is assumed that the pressure in the pump discharge pipe 9 is Pd, and the pressure inside the cylinder is Po.

In Figure 3, if the penetration resistance of the pile is infinite, the displacement of the plunger 3 is zero, and the entire pile hammer moves upward by y, then the mass of the pile hammer is expressed by m, and the cross-sectional area of the cylinder 2 is A. Then, it becomes .

Between the flow rate and the displacement y of the twisted fluid conduit 10, the cylinder 2
Assuming that the equivalent volume is 0 Ve, the rate of change in volume here is expressed as β.

Differentiate this with t, organize, get.

Substituting equation (9) into equation α0, substituting this into equation (8), and rearranging.

However, pd〈〈po, and (ignoring pd in formula 0).

It is expressed as

C1 and C2 are constants. When t = o, po:
o (pd << po and pd o2)
Then, C1=o, and the formula 0 becomes as follows.

Differentiate the α test, That's what I mean.

Hey, Z-U. is the fluid conduit 10 just before the on-off valve 14 closes.
is the flow velocity within.

Therefore, 0 (from the experiment, the constant C2 is becomes.

Therefore, the pressure inside cylinder 2 is It is expressed as

The maximum value of po, that is, the maximum pressure that determines the maximum penetration force is Totoru.

Penetration force at this time becomes.

pressure p. is sinusoidal and p o < .

p because the on-off valve 14 opens.

At the part where is a sin curve and becomes a hole, the fluid flows into the fluid conduit 10.
There is no negative pressure because the flow is reversed inside.

FIG. 4 is a diagram showing the above operating situation.

When the on-off valve 14 remains open, the flow velocity U in the fluid conduit 10 increases, and at the same time, the discharge pressure pd of the pump 7 decreases.

Instant opening/closing valve 14 when the discharge pressure pd of the pump 7 reaches pm
is closed, and the discharge pressure pd of the pump 7 increases rapidly.

The flow velocity U also decreases in a wave-like manner.

A sinusoidal pressure will be generated within the cylinder 2.

By the way, try substituting specific numerical values into equation (e).

The inner diameter of the fluid conduit 10 is 0.1 m, the length is 50 m, the equivalent volume Ve = 0.3 m3, the weight of the pile hammer is 100
00kf, the inner diameter of cylinder 2 is 0.3m, the fluid is water,
Is the volume change rate β lXl0-8rr? /1. , fluid conduit 1
The flow velocity U when the on-off valve 14 is about to close is within 0.

If 30m/8oc, Pomax = 170
kg/crA and WmaX=120 ton.

The above explanation refers to the penetration force when the penetration resistance of the pile is infinite, but in reality, the pile is penetrated, so the pressure and flow rate of the fluid are used for the penetration work.

When the penetration resistance is large, a thick pressure is generated.When the penetration resistance is small, the amount of penetration is large and the pressure is large.
No.

In either case, pressure is generated in waves due to the water hammer effect that occurs the moment the on-off valve 14 is closed.

Due to this large pressure, downward pressure is applied to the plunger 3 to which one end of the pile P is attached, and upward pressure is applied to the cylinder 2 and other members where the residue is present.

In this case, since a large pressure is generated below the on-off valve 14, the on-off valve 14 closes and does not open, but the next moment the pressure becomes low in waves due to the water hammer action.

In this case, since the pump 7 is in the closed-off continuous state, the on-off valve 14 is opened again, the velocity of the fluid in the fluid conduit 10 increases, and the on-off valve 14 is closed again in the same manner as in the above case. Generates water hammer effect.

The above operations are automatically repeated while the pump 7 is in operation, and the piles P are successively driven into the soil by downward pressure acting intermittently on the plunger 3.

The downward pressure generated by the above-mentioned water hammer action and acting on the plunger 3 depends on the length of the fluid conduit 10 (more precisely, the length of the flow path), fluid density, fluid deceleration (acceleration in the negative direction), etc. However, the deceleration of the fluid depends on the hardness of the ground into which the pile P is to be driven. If the ground is soft, the moment the on-off valve 14 is closed, high pressure is generated in the valve chamber 14a and the plunger is 3 moves downward together with the pile P, the flow of fluid in the fluid conduit 10 does not become zero and the deceleration of its flow velocity does not become so large.

However, since the high pressure is maintained within the valve chamber 14a for a short time, the plunger 3 drives the pile P efficiently.

On the other hand, if the ground is hard, the plunger 3 will hardly move downward due to its resistance, so the cylinder 2 and other parts will move upward due to the high pressure, but this inertial force is quite large, so High pressure is in the valve chamber 14a
The plunger 3 drives the pile P due to the pressure generated inside the pile P, albeit slightly.

According to this type of pile hammer, the pressure acting on the plunger 3 is generated in the valve chamber 14a depending on whether the ground is soft or hard, so that it is possible to drive piles into a wide range of ground.

In addition, since an electric motor is used for power, there is no generation of exhaust gas, and since the pile is driven by pushbuttons and fluid pressure, there is little mechanical noise or vibration.

The purpose of the pile hammer of the present application is to use the wave-like high pressure generated when the flow in the long fluid conduit 10 is momentarily stopped to penetrate the pile. Of course, it is possible to open and close by detecting the discharge pressure of the pump 7 as shown in the embodiment, but if the flow rate becomes faster or the timing
The effects of the present application can be obtained by closing the on-off valve for damming the high-speed fluid by opening and closing it from the outside using the valve 9 or by using other means.

Since the pile hammer of the present invention has the above-described configuration and function, according to the present invention, (1) piles can be driven into a wide range of ground ranging from soft to hard.

(Odor) Since there is no emission of exhaust gas, and there is little mechanical noise or vibration, there are no buttons that cause environmental pollution problems, and therefore there are no buttons that are restricted from use in urban areas.

The following practical effects can be mentioned.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic reduced cross-sectional view of an embodiment of the present invention. FIG. 2 is a characteristic diagram of the pump, and is an explanatory diagram showing the opening/closing points of the on-off valve 14. FIG. 3 is a model diagram for explaining the operation of the pile hammer of the present application, and FIG. 4 is a diagram showing the operating state. 1: Outer cylinder, 2: Bottom cylinder, 3 Ni lunge gear, 5: Inner cylinder, 7: Pump, 8: Electric motor, 9: Pump discharge pipe, 10
: spiral fluid conduit, 11: accumulator, 14: on-off valve, 14a: valve chamber, 14c: valve port, 15: connecting rod, 15
a: Piston, 16: Cylinder for operating the on-off valve.

Claims (1)

[Claims] 1. An outer cylinder having a bottom cylinder fluid-tightly attached to its lower end opening; an inner cylinder disposed concentrically within the outer cylinder and having its lower end opening fluid-tightly fixed to the periphery of the upper end of the valve port of the bottom cylinder; ,
A pump having one side of the casing fixed to the upper end of the inner cylinder so that the suction port is communicated with the upper end opening of the inner cylinder, and a ring-shaped pump formed between the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder. within the space,
A fluid conduit spirally arranged along the vertical direction, having an upper end opening communicated with the discharge pipe of the pump and a lower end opening fluid-tightly connected to the valve chamber of the bottom cylinder; A pile hammer 0 characterized in that it is equipped with a plunger attached to the bottom cylinder, and an on-off valve disposed in the valve chamber of the bottom cylinder.