JP2729023B2 - Method and device for controlling vibratory force in pile driving work - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for controlling the vibrating force of a vibrator used in a vibratory pile driving work.

[0002]

2. Description of the Related Art In a vibration pile driving method, a pile is vibrated to penetrate into the ground by its own weight. 7A and 7B are views for explaining a vibrating pile driving method according to the related art, in which FIG. 7A is a schematic cross-sectional view, and FIG. 7B is felt by a human body on the ground by the driving depth of the pile. It is a chart showing the situation where the seismic intensity changes. As shown in FIG. 7A, a vibration device 17 composed of a vibration exciter is hung by a crane boom 22, and a pile 20 is clamped by a chuck 17a attached to the vibration device (vibration exciter). When the lifting force of the crane boom 22 is relaxed while giving vibration to the pile 20 by the vibration device, the pile 20 sinks underground by its own weight. The surface wave j generated at the beginning of the pile driving operation is not usually very strong, but may propagate to the private house 23 to cause vibration pollution. The underground wave b generated because the tip of the pile 20 penetrates while crushing the stratum attenuates before reaching the private house 23 as the depth increases.

[0003] The ground is usually not uniform, and is formed of a stratum composed of various geological features. However, ignoring such geological composition, the driving depth of the pile (the distance between the tip of the pile and the ground surface) is generally considered. It is widely known as an empirical rule that there is a relationship as shown in Fig. 7 (B) between the distance of the human body and the seismic intensity which the human body on the ground feels sensually. Similarly, the seismic intensity is not always proportional to the vibrational energy, as the pile driving depth increases, but the seismic intensity gradually increases,
After the maximum seismic intensity point m, it starts to decrease gradually. This is because the underground wave b is attenuated as described with reference to the diagram (A), and the depth at this point m varies depending on the geology, but is generally 3 to 5 m. As the driving depth further increases, the bodily seismic intensity at the point d in the figure becomes equal to the ground surface (specifically, at the beginning of the driving operation, the bodily seismic intensity becomes the same as when the tip of the pile starts to penetrate the ground surface). When the pile driving depth is deeper than the point m, the seismic intensity further decreases. In other words, even if a large vibrating force is generated by the vibration device (vibrator) 17, the body seismic intensity is relatively small.

Considering the use of the body seismic intensity curve 25 obtained by such an empirical rule, the vicinity of the point m shown in FIG. It is expected that when the driving force is gradually increased after the point d in the drawing and the rapid driving is performed, the vibration pile driving operation can be performed with relatively high efficiency while suppressing the vibration pollution. Next, the adjustment of the excitation force of the exciter will be described. 8A and 8B show a conventional vibration exciter and its operating principle. FIG. 8A is an explanatory view of the most basic single-axis eccentric weight unit, and FIG. Explanatory drawing of a 4-axis synchronous / left / right balanced eccentric weight composed of four pieces, (C) is an explanatory view of an eccentric variable weight that is an improvement of the single-axis eccentric weight, and (D) is the same weight mounting. It is explanatory drawing of the eccentric amount variable weight by adjusting an angle. (A) In the drawing, 1 is a rotating shaft, 2 is an eccentric weight, and a point G in the drawing is shown.
Represents the position of the center of gravity, and A is the radius of rotation of the center of gravity G. The eccentric weight 2 is rotated around the rotation axis 1 by an angular frequency ω.
When rotated at rad / sec or 1 / sec, an acceleration a of a = Aω ² (1) is generated.

[0005] However, the vibratory pile driving operation requires vertical vibration, and horizontal vibration is not only necessary but also an obstacle. Therefore, when the eccentric weights 2A and 2B are arranged and rotated synchronously as shown in FIG. 6B, the vibration component in the horizontal direction (horizontal) is canceled out, and the acceleration of a single vibration in the vertical direction is calculated as a = 2Aω ² (2) is obtained.

Further, as shown in the figure, four eccentric weights 2
By providing A, 2B, 2C, and 2D and rotating them synchronously, a = 4Aω ² ... (3) is obtained. The basic operation of such a four-axis eccentric weight is also the one-axis eccentric weight unit shown in FIG.

FIG. 3C shows a uniaxial eccentric weight unit improved to vary the amount of eccentricity, and has openings 3a, 3b, 3c. An adjustment weight (for example, 3
When d) is fitted and fixed, the substantial amount of eccentricity increases. The eccentricity can be adjusted as desired by appropriately changing the weight and the number of the weights for adjustment. In the conventional example shown in FIG. (D), as shown in FIG. (C) above, a separate member (for example, the amount of eccentricity can be adjusted without attaching and detaching the adjusting weight 3d, Two eccentric weights 4A and 4B are attached to the rotating shaft 1. Ga shown in FIG.
The center of gravity of A, Gb is the center of gravity of the eccentric weight 4B, mA is a line connecting the center of the rotating shaft 1 and the center of gravity Ga, and mB is a line connecting the center of the rotating shaft 1 and the center of gravity Gb. The angle θ between the two lines mA and mB is arbitrarily adjusted to provide two eccentric weights 4.
When the eccentric weights A and 4B are rotated around the rotation axis 1, the portion where the two eccentric weights 4A and 4B overlap (shown with spots) acts as an eccentric weight. Therefore, the amount of eccentricity can be adjusted by changing the angle θ. If the eccentricity of the eccentric weight unit can be adjusted to control the vibrating force by any of the above methods (C) and (D), the four axes as shown in FIG. With respect to the multi-axial type vibration exciter, the vibration generation force can be controlled in the same manner.

[0008]

As described with reference to FIG. 7B, the relationship between the driving depth of the pile (vertical axis) and the seismic intensity (horizontal axis) is known as an empirical rule. 8
As described in (C) and (D), a method of adjusting the vibrating force is also known. Therefore, by combining these two techniques and trying to increase the working efficiency as much as possible while suppressing vibration pollution as much as possible, the curve 26 shown in FIG.
It is conceivable that the vibrating force is changed as follows. The excitation force control curve 26 according to the related art is based on the idea that the excitation force is controlled so as to be approximately inversely proportional to the above-described body sensation degree curve 25. However, the following two points are different from the virtual curve inversely proportional to the seismic intensity curve.

B. In the vicinity of the driving depth of 0, that is, in the vicinity of the ground surface, the vibrating force is reduced irrespective of the decrease of the seismic intensity curve. This takes into account the influence of the surface wave j described with reference to FIG. 7A and the influence of noise. B. It does not make a curve, but is a broken line curve. This depends on the following circumstances. In other words, to change the vibrating force over the range u shown in the figure, it is not enough to change the rotational speed of the eccentric weight, but to change the amount of eccentricity. However, according to the eccentricity adjusting method shown in FIG. 8C and the eccentricity adjusting method shown in FIG. 8D, the exciter must be temporarily stopped, partially disassembled, and reassembled. For this reason, the vibrating force changes stepwise as shown by the curve 26. In the illustrated curve 26, a horizontal portion indicates that the vibrating force has increased due to a change in the amount of eccentricity (replacement work of the vibrator), and a vertical linear portion of the curve 26 is inclined. Indicates that the rotational speed was steplessly increased.

However, there are the following major disadvantages in changing the vibrating force as in the curve 26. [Problem 1] The work of stopping the vibration exciter and reassembling around the eccentric weight during the pile driving work requires a great deal of time and labor. In addition, as shown in FIG. 7A, the vibration device including the vibration exciter is mounted on the top of the pile 20, and it is dangerous to perform the re-arrangement work as it is. After hanging down on the ground and reassembling, lift it up again and pile 2
Attaching to the top of the zero wastes additional time and effort. [Problem 2] Vibration pile driving works to penetrate the pile while breaking the stable ground, but if the work is interrupted, the ground will be restored to a stable state (usually it is said that the ground is recovered or the soil is tightened)・ This phenomenon is particularly remarkable in clayey strata, but is observed in almost all geology.) For this reason, if the vibration pile driving operation is interrupted and a certain period of time has passed, there is a possibility that the pile will not settle even if the operation is restarted and the vibration is applied. Due to such a problem, it is customary to control the vibrating force only by adjusting the rotational speed without changing the eccentric amount in the middle, as shown by a curve 27 shown by a dotted line in FIG. The vibrating force change range v of the vibrating force control curve 27 when only the rotation speed is changed is smaller than the vibrating force change range u of the vibrating force control curve 26 when the rotation speed and the amount of eccentricity are changed. And naturally narrow. For this reason, in the vibrating force control (constant eccentricity) in which only the rotation speed is changed, it is not possible to achieve both the prevention of the vibration pollution and the high-efficiency construction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has no risk of impairing a pile due to interruption of work (tightening due to restoration of ground) without lowering work efficiency and preventing pollution. It is an object of the present invention to provide a method for controlling a vibrating force and a control device capable of minimizing vibration.

[0012]

In order to achieve the above object, the present invention relates to a vibration device of Japanese Patent Application No. 2-223030.
A vibration exciter capable of adjusting the amount of eccentricity steplessly during operation is used. The technique according to the prior application basically changes the mounting angle of the eccentric weight as described with reference to FIG. 8D, but by using a special coil spring, the eccentric weight can be stopped without stopping the apparatus. The weight is rotated relatively to the rotation axis. 2A and 2B show a special coil spring used in the vibration exciter according to the prior application, wherein FIG. 2A is a side view, and FIG. 2B is a schematic development view in a state where it is desired to receive a force in a thrust direction. (C) is a schematic developed view illustrating a state in which a force in the thrust direction (vertical direction in the figure) is received. The special coil spring (symbol 6) is shown in FIG.
If a compressive force is applied in the vertical direction in the figure from the state of (B), a slip occurs as shown in FIG. That is, if the upper side is fixed now, the lower side moves in the direction of arrow f. Displacement in the direction of arrow f in the developed view (C) means that it is rotated in the direction of the arc F in the side view (A), and this action is utilized. FIG. 3 shows a main part of a vibration device according to the prior application, which is configured so that the amount of eccentricity can be adjusted steplessly during operation by using the above-mentioned special coil spring. FIG. The rotating shaft 7 is rotatably supported by a bearing 9 with respect to a case 9. A plurality of the rotating shafts 7 are provided, and one of the rotating shafts 7 is illustrated in the drawing. The plurality of rotating shafts 7 are gears 1
4 through which they are rotated in synchronism with one another. The movable eccentric weight 8 is supported by a bearing 11 so as to be rotatable with respect to the rotation shaft 7 and not to slide in the axial direction. A pushing member 13 is externally fitted to the rotation shaft 7 via a screw spline 12. Thereby, when the pushing member 13 is pushed to the left in the figure, the screw spline 12
Is slightly rotated and pushed to the left in the figure. Both ends of the special coil spring 6 described with reference to FIG. 2 are fixed to the pushing member 13 and the movable eccentric weight 8 described above. The rotating shaft 7 has a gear 14
, And the movable eccentric weight 8 is also rotated. In this state, when a leftward force is applied to the pressing member 13 via the bearing 15 and the plate 16, the special coil spring 6 is compressed. The special coil spring 6 generates a rotational torque around the axis while contracting in the axis direction, and is torsively deformed. Similarly, the pushing member 13 also rotates by the action of the screw spline 12, and the mounting angle of the movable eccentric weight 8 changes by the total angle of the amount of torsional deformation and the amount of rotation (relative to the rotating shaft 7). Is rotated). In this way, the mounting angle of the movable eccentric weight 8 can be changed while the rotating shaft 7 is rotating without interrupting the operation. Although FIG. 3 shows only one rotary shaft 7 and one movable eccentric weight 8, a mechanism similar to that of FIG. 3 (however, the relative rotation of the movable eccentric weight relative to the rotary axis) is shown. The direction is opposite to that of Fig. 3 (so-called left-right difference or mirror image symmetry).
By changing the mounting angle of the movable eccentric weight, the total amount of eccentricity can be changed. When the amount of eccentricity is changed as described above, it is possible to change the vibrating force even when rotating at a constant speed. If the rotation speed is also changed, the variable range of the vibrating force is further increased.

[0013] In order to achieve the above object (vibration pollution prevention) using the above-described mechanism, a method for controlling a vibrating force according to the present invention comprises the steps of: In the method of controlling a. When a constant vibration is applied to the pile, the seismic intensity that the human body senses sensuously on the surface of the ground is used as the standard for vibration control,
After the body seismic intensity increases with an increase in the pile driving depth dimension, a gradually decreasing body seismic intensity curve is obtained, b. The magnitude of the vibrating force is steplessly changed so as to be substantially inversely proportional to the above-mentioned seismic intensity curve.

Further, a control device for a vibrating force according to the present invention, which was created in order to easily implement the above-mentioned control method and sufficiently exert its effects, comprises: a. A storage circuit for storing a relationship between a driving depth dimension of the pile and a seismic intensity at which a human body on the ground senses vibration generated by driving the pile, b. A driving depth sensor for detecting the current value of the driving depth of the pile; c. A bodily sensibility calculation circuit for calculating a bodily seismic intensity corresponding to the driving depth dimension based on the output signal of the driving depth sensor; d. And a command signal calculation circuit that outputs a command signal to change the vibrating force of the vibration exciter so as to be substantially in inverse proportion to the calculated body seismic intensity.

[0015]

When the control method of the vibrating pile driving work is performed using the control device described above, the pile driving depth is gradually increased until the pile reaches a depth corresponding to the maximum seismic intensity point m. Preventing or remarkably reducing vibration pollution by saving the excitation force, in the process of driving deeper than the maximum seismic intensity point m, by increasing the excitation force in inverse proportion to the decrease of the seismic intensity curve , Construction can be performed with maximum work efficiency while suppressing vibration pollution.
It is not necessary to stop the exciter during the pile driving work and perform the rearrangement work, so that not only is time and labor wasted, but also the pile recovery is required for the restoration of the ground (consolidation of soil) due to the interruption of the pile driving work. There is no danger of causing trouble that subsidence (penetration into the ground) becomes impossible.

[0016]

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an embodiment of a method of controlling an exciting force in a pile driving work according to the present invention, in which the vertical axis indicates the pile driving depth downward, and the horizontal axis indicates the excitatory force and the seismic intensity. (A) shows a control curve assuming a standard state irrespective of the geology, and (B) gives a range of the vibrating force according to the geology, based on the control curve. The control zone is shown, and both figures are charts drawn on the same coordinates so that they can be compared with the seismic intensity curve. 1A is the body seismic intensity curve described above with reference to FIG. 7B, m is the maximum body seismic intensity point, and d is the point where the body seismic intensity becomes equal to the ground surface. The control method according to the present invention changes the eccentricity and the rotation speed of the exciter steplessly as the driving depth of the pile becomes gradually deeper, and basically changes it in inverse proportion to the body seismic intensity curve. Change the excitation force. However, the inverse proportion in the present invention does not need to be strictly inversely proportional to the analytic geometry, and means “to the opposite tendency”. Note that the stepless control curve 29 in the present embodiment has a maximum body seismic intensity point m
Takes the minimum value (to the left on the surface of the figure) at the depth corresponding to, but also in the area shallower than the depth corresponding to this maximum seismic intensity point m, the above-mentioned minimum value is maintained substantially (curve 28 is almost Vertical). This takes into account the effects of surface waves and noise on nearby private houses.

As shown by the above-mentioned stepless control curve 29, the driving is started with the vibrating force reduced near the ground surface, and the vibrating force is too large up to the depth corresponding to the maximum seismic intensity point m. And minimize vibration pollution to neighboring houses. When the pile driving depth is shallow, the friction area between the pile and the ground is small, so that even if the vibrating force is suppressed, it is not impossible for the pile to sink (penetrate into the ground). When the driving depth exceeds the maximum seismic intensity point m, the main epicenter (lower end of the pile)
Becomes deeper, the propagation distance of the underground wave becomes longer, and the attenuation gradually becomes remarkable (the seismic intensity curve 25 shifts to the left of the figure)
Therefore, the stepless control curve 29 is gradually increased (toward the right side of the figure).

As described above, a control device for increasing the vibrating force in accordance with the change in the pile driving depth and changing the vibrating force along the stepless control curve 29 will be described.
FIG. 4 shows an embodiment of a vibration control device according to the present invention,
It is a block diagram drawn partially in schematic form. In FIG. 4, reference numeral 20 denotes a pile, and reference numeral 17 denotes a vibrating pile driving device including a vibration exciter, on which a pile driving depth sensor 21 is mounted. When carrying out the present invention, sensor 21 for detecting the implantation depth L ₂ of the pile can be selected and used appropriately known techniques, for example, ground clearance shown by the non-contact distance sensors L ₁ may be calculated depth L ₂ implantation by measuring. Numeral 31 denotes a storage device for the seismic intensity curve, which is shown in FIG.
The body seismic intensity curve 25 described with reference to FIG. 1B and FIG. 1A is stored. The reference numeral 32 denotes an arithmetic circuit (abbreviation / body sensibility calculation circuit) for calculating the body sensation level. When a signal is received from the driving depth sensor 21, information is transmitted to and received from the body sensation level curve storage circuit. performed while calculates the experience seismic intensity value commensurate with the current value L ₂ of the implantation depth of the pile 20, the command signal calculation circuit 33 that calculates the signal output
Give to. The command signal calculation circuit 33 calculates an appropriate vibrating force (a value of the vibrating force given by the stepless control curve 29 described with reference to FIG. Control. This vibration exciter 17 is shown in FIG.
In this manner, not only the rotational speed but also the eccentricity can be arbitrarily adjusted over a wide range while the operation is continued, so that the vibrating force can be controlled steplessly. That is, it can be changed along the stepless control curve 29 described above.

A curve 28 shown by a dotted line in FIG.
This is a virtual curve drawn so as to be symmetrical with the body seismic intensity curve 25, and the stepless control curve of this embodiment is basically set to the same shape as this virtual symmetrical curve 28. FIG. 1A shows a different shape depending on circumstances. [Reason 1] In this chart, the exciting force and the body seismic intensity are expressed on the horizontal axis for the sake of convenience, but both have the same dimensions, but the scales are not necessarily the same. [Reason 2] In the range where the maximum seismic intensity point m is deeper than the corresponding pile driving depth, the stepless control curve 29 has almost the same tendency as the imaginary symmetric curve 28, and the deeper the depth, the greater the vibrating force. . However, the maximum seismic intensity point m
In a range shallower than the pile driving depth corresponding to, the value is substantially constant and small. That is, if a point on the stepless control curve 29 having a depth dimension corresponding to the point m is designated as M, the stepless control curve has a substantially constant value from the point M upward (virtual). It does not decrease following the symmetry curve 28). This is a measure to prevent surface waves and noise from being given to nearby people when there are houses near the pile driving work site.

The embodiment described above with reference to FIGS. 1A and 4 is an example in which standard excitation force control is performed without special consideration of the stratum structure. This is referred to as a first embodiment. Next, a second embodiment in which finer control is performed according to the stratum structure will be described. Reference numeral 29 shown in FIG. 1B is a stepless control curve similar to that in the first embodiment. In the second embodiment, the stepless control curve is the same as the reference, but in the present embodiment, the control zone 30 is set with a certain width, and the range of the zone is set. Adjust by increasing or decreasing the vibrating force within. The above adjustment causes the pile tip to vibrate in inverse proportion to the magnitude of the N value according to the hardness of the stratum at the current position of the tip of the pile, specifically, the N value of the stratum where the tip of the pile is currently crushing. To moderate the power. The reason is that, for example, in the case of a stratum having a high N value (hard) such as mudstone, the vibrating force is made weaker than the stepless control curve 29 (to the left in FIG. 1B). Minimize vibration generation. Also, for example, low N value (soft) like muddy soil
In the case of a stratum, vibration pollution is unlikely to occur, so the vibrating force is strengthened (to the right in the figure) to improve the work efficiency.

In the second embodiment, it is necessary to know the N value, more specifically, to know the N value of the stratum where the tip of the pile being driven has actually reached. The N value is accurately determined by using an N meter while observing the state where the test bar penetrates into the ground due to the impact of the falling of the weight, but if the type of geology is known without necessarily using the N meter. It can be estimated fairly accurately by empirical rules. For example, if the stratum structure is known by test boring,
Based on this, it is possible to perform the second embodiment (further increasing or decreasing the vibrating force based on the stepless control curve 29). If the stratum structure is unknown, it is determined by reflected wave analysis. FIG. 5 is a schematic vertical cross-sectional view for explaining a method of geological exploration by reflected wave analysis, in which (A) depicts an example in which a vibration transmitter and a vibration receiver are installed on the surface of the ground,
(B) illustrates an example in which a vibration transmitter is mounted on a vibration pile driving device including a vibration exciter and a vibration receiver is mounted on a pile. (A) The method of the figure is a widely known and classical technique, in which vibrations are radiated from the ground surface transmitter 18 into the ground (for example, vibration may be given by explosives), and from the boundary surface of each layer. The reflected vibration is received by the receiver 19 on the ground surface, and the stratum structure can be estimated based on the strengths and phases of many received waves. (B) The method shown in the figure has been developed by the present inventor. A vibration signal is transmitted from a transmitter 18 attached to a vibrator 17 and a reflected wave is received by a receiver attached to a pile 20. In particular, by selecting and analyzing the reflected wave from the tip of the pile 20, it is possible to identify the geology (the silt layer in the example of this figure) to which the tip of the pile 20 faces. Although various similar technologies have been proposed for the geological analysis method of FIG. 5B, an arbitrary method can be selected and applied. The novelty of the present invention lies in adjusting the vibrating force within the control range shown in FIG. 1B based on the N value (hard and soft) of the geology at the tip of the pile. Next, an apparatus for the second embodiment will be described. FIG. 6 shows a vibrating force control device 1 configured to carry out a vibrating force control method of a method of increasing / decreasing a vibrating force based on an N value of a stratum.
FIG. 2 is a schematic block diagram illustrating an embodiment. Driving depth sensor 21, pile 20, exciter 1 shown in FIG.
7, transmitter 18, receiver 19, body sensation degree curve storage circuit 31, body sensation degree calculation circuit 32, and command signal calculation circuit 3
Reference numeral 3 is a component similar to or similar to the component in the first embodiment shown in FIG. The vibration signal generation circuit 35 shown in FIG. 6 creates a signal waveform that can be easily distinguished from other signals and supplies the signal waveform to the transmitter 18. Since the pile 20 and the exciter 17 and the vicinity thereof are vibrated for driving the pile and its harmonics and reflected waves are mixed and propagated, the vibration waveform having a frequency that can be easily selected from these noises is obtained. It is necessary to set and oscillate the vibration signal generation circuit 35. The vibration signal radiated from the oscillator 18 is
And is reflected by the geology (silt layer in this example) facing the tip, and is received by the receiver 19. The reflected wave includes a reflected stratum (in this example, a waveform component peculiar to the silt layer), so the N value calculation circuit 36 identifies the type of the stratum by analyzing the waveform of the reflected wave, The N layer is calculated and given to the command signal correction circuit 34. The role of the command signal correction circuit is to give an increase or decrease based on the N value to the output signal of the command signal calculation circuit 33. 1 (B), the stepping control curve 29 (FIG. 1 (B)) output from the command signal calculation circuit 33 (FIG. 6) is subjected to an increase or decrease in the vibrating force, so that the control area zone 30 ( 1B, the intensity of the vibrating force is adjusted within the range shown in FIG.1B, which allows finer control than the vibrating force control based on only the stepless control curve 29 as in the first embodiment. To perform pile driving with high efficiency while suppressing vibration pollution Rukoto can.

At the start of the stakeout operation, if the stratum structure is known in advance by test boring or the like, the information is stored in the N value calculation circuit 36 shown in FIG. It is also possible to provide an N value. In this case, wiring (not shown) for directly or indirectly supplying the output signal of the driving depth sensor 21 to the N value calculation circuit 36 is required.

As can be easily inferred from the above-described functions and effects, the oscillator 18 shown in FIGS.
Does not necessarily have to be mounted on the exciter 17, and the same operation and effect can be obtained by mounting on the pile 20 or a component fixed to the pile 20. FIG.
(B) and the receiver 19 shown in FIG. 4 and FIG.
It does not necessarily have to be attached to the upper part of the pile 20, and the attachment position is not limited. Attaching the receiver 19 to the tip (lower end) of the pile 20 is also a theoretically desirable configuration. However, in this case, pile 2
Since the receiver 19 sinks into the ground with 0, it is necessary to provide an appropriate protector (not shown). Further, an electric wire for transmitting the reception signal sent from the receiver 19 is provided on the pile 20. It must be installed alongside, and a protector must be provided to protect it from earth, sand and rock.

Further, as an embodiment different from the above, when the stratum structure is known in advance, the operator manually operates the apparatus shown in FIG. 1B without using the control device shown in FIG. The same control as in the second embodiment can be performed. The pile driving depth sensor 2 shown in FIGS.
The worker can use the pile depth L ₂ (Fig. 4) without using 1.
And it is also possible to control the vibratory force tighten along steplessly control curve 29 shown in FIG. 1 (A) by the calculated while manual operation based on visual estimation of dimensions L ₁ shown.

[0025]

When the control method of the vibrating pile driving work is carried out by using the control device according to the present invention, the driving depth of the pile is gradually increased to a depth dimension corresponding to the maximum seismic intensity point m. During the process, the vibration force can be saved to prevent or significantly reduce vibration pollution, and in the process of driving deeper than the maximum seismic intensity point m, the vibratory force increases in inverse proportion to the decrease in the seismic intensity curve By doing so, construction can be performed with maximum work efficiency while suppressing vibration pollution. In addition, there is no need to stop the vibration exciter during the pile driving work and perform the replacement work, which saves time and labor. An excellent practical effect that not only does not waste, but there is no danger that the pile will not be able to sink (penetrate into the ground) due to the restoration of the ground (consolidation of the soil) due to the interruption of the pile driving work, which will not be possible. To play.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a method of controlling a vibration generating force in a pile driving work according to the present invention, in which a vertical axis indicates a driving depth of a pile downward and a horizontal axis indicates a vibration generating force and a body seismic intensity. (A) shows a control curve assuming a standard state irrespective of the geology, and (B) gives a range of the vibrating force according to the geology, based on the control curve. The control zone is shown, and both figures are charts drawn on the same coordinates so that they can be compared with the seismic intensity curve.

FIG. 2 shows a special coil spring used in the vibration exciter according to the prior application, wherein (A) is a side view, and (B) is a schematic developed view in a state where it is desired to receive a force in a thrust direction.
(C) is a schematic developed view illustrating a state in which a force in the thrust direction (vertical direction in the figure) is received.

FIG. 3 shows a main part of the vibration device according to the prior application, which is configured so that the amount of eccentricity can be adjusted steplessly during operation by using the special coil spring, and is a partially cutaway front view. FIG.

FIG. 4 is a block diagram showing an embodiment of a vibration generating force control apparatus according to the present invention, which is partially schematically drawn.

FIG. 5 is a schematic vertical cross-sectional view for explaining a method of geological exploration by reflected wave analysis, in which (A) depicts an example in which a vibration transmitter and a vibration receiver are installed on the surface, and (B) Shows an example in which a vibration transmitter is attached to a vibration pile driving device consisting of an exciter and a vibration receiver is attached to a pile.

FIG. 6 is a schematic block diagram showing an embodiment of a vibrating force control device configured to execute a vibrating force control method of increasing or decreasing a vibrating force based on an N value of a stratum; FIG.

7A and 7B are views for explaining a vibrating pile driving method according to the related art, in which FIG. 7A is a schematic cross-sectional view, and FIG. 7B is a view showing a human body on the ground according to the driving depth of the pile. It is a chart showing the situation where the felt seismic intensity changes.

8A and 8B show a conventional vibration exciter and its operating principle, wherein FIG. 8A is an explanatory view of the most basic one-axis eccentric weight unit, and FIG. Explanatory drawing of an eccentric weight of four-axis synchronous and left-right balance type consisting of four,
(C) is an explanatory diagram of an eccentric amount variable weight obtained by improving the single-axis eccentric weight, and (D) is an explanatory diagram of the eccentric amount variable weight by adjusting the weight mounting angle.

FIG. 9 shows a conventional example of vibration control in a pile driving method,
It is a chart in which the pile driving depth is plotted on the vertical axis and the vibrating force is plotted on the horizontal axis.

[Explanation of symbols]

1, 1A-1D: rotating shaft, 2, 2A-2D: eccentric weight,
3: eccentric weight, 3a-3c: opening, 3d: adjusting weight,
4A, 4B: Eccentric weight, 6: Special coil spring, 7
... Rotating shaft, 8 ... Movable eccentric weight, 9 ... Case, 10, 11
... bearing, 12 ... screw spline, 13 ... pushing member, 14 ... gear, 15 ... bearing, 16 ... plate,
17: vibrating device composed of a vibrator, 17a: chuck, 1
8: Oscillator, 19: Receiver, 20: Pile, 21: Driving depth sensor, 22: Crane boom, 23: Private house, 25: Body seismic intensity curve, 26: Conventional technology in which rotation speed and eccentric amount are changed Exciting force control curve according to the related art, 27 ... Exciting force control curve according to the prior art in which only the rotation speed is changed and the eccentricity is constant, 28 ... A virtual symmetrical curve, 29 ... Stepless control curve, 30 ... Control area Band, 31: body sensibility curve storage circuit, 32: body sensibility calculation circuit, 33: command signal calculation circuit, 34: command signal correction circuit, 35: vibration signal generation circuit, 36: N value calculation circuit.

Claims (11)

(57) [Claims] 1. A method for controlling a vibrating force of a vibrator when performing a vibrating pile driving work, comprising: a. When a constant excitation force is applied to the pile, the seismic intensity, which is sensed by the human body sensuously on the surface of the ground, is used as the basis for the excitation force control.After the seismic intensity increases with the pile depth, Obtain a gradually decreasing seismic intensity curve, b. A method of controlling a vibrating force in a pile driving work, wherein the magnitude of the vibrating force is steplessly changed so as to be substantially inversely proportional to the above-mentioned seismic intensity curve. 2. The method according to claim 1, wherein the magnitude of the vibrating force is changed by changing not only the rotational speed of the eccentric weight type vibrator but also the amount of eccentricity of the eccentric weight. The method of controlling the excitation force in the pile driving work described in. 3. The maximum body seismic intensity point at which the body seismic intensity starts decreasing after the body seismic intensity increases with an increase in the driving depth of the pile, and the pile corresponding to the maximum body seismic intensity point is taken. 3. The method of controlling a vibrating force in a pile driving work according to claim 1, wherein the pile is driven with a substantially constant vibrating force until the driving depth reaches the driving depth. 4. a. Assuming a stepless control curve that is substantially inversely proportional to the seismic intensity curve, and setting a control zone in which the stepless control curve has a width; b. Within the range of the control zone, according to the N value of the stratum where the tip of the pile is located, decrease the eccentricity when the N value is small, and increase the eccentricity when the N value is large. 2. The method according to claim 1, wherein
Or, a method for controlling a vibrating force in a pile driving work described in 2 above. 5. When the configuration of the formation and the N value are known, the control zone of the pile driving exciter is stored in the automatic control device, and the excitation force is increased or decreased according to the N value. 5. The method according to claim 4, wherein a program is applied to automatically change the excitation force. 6. When the stratum composition at the place where the pile is driven is unknown, a stepless control curve substantially in inverse proportion to the body seismic intensity curve is set and stored in the automatic control device of the pile driving exciter. The method according to any one of claims 1 to 3, wherein the excitation force is changed according to a step control curve. 7. When the formation of the stratum where the pile is to be driven is unknown, a signal vibration transmitter is attached to the exciter or the pile, and the pile is mounted on the pile at a location separated from the transmitter to reduce the signal vibration. A receiver is attached, the signal vibration transmitted from the transmitter and reflected from the tip of the pile is received by the receiver, the received signal vibration reflected wave is analyzed, and the type of the formation in contact with the tip of the pile and The N value is determined, and the amount of eccentricity of the eccentric weight of the exciter is increased or decreased based on the determined N value. Method. 8. An apparatus for controlling a vibration exciter for driving a vibrating pile, comprising: a. A storage circuit for storing a relationship between a driving depth dimension of the pile and a seismic intensity at which a human body on the ground senses vibration generated by driving the pile, b. A driving depth sensor for detecting the current value of the driving depth of the pile; c. A bodily sensibility calculation circuit for calculating a bodily seismic intensity corresponding to the driving depth dimension based on the output signal of the driving depth sensor; d. A command signal calculation circuit that outputs a command signal to change the vibrating force of the vibration exciter so as to be approximately in inverse proportion to the calculated body seismic intensity. Control device of vibration force. 9. A command signal operation circuit for outputting the command signal, wherein a geological configuration and a N
9. The control device according to claim 8, further comprising a signal correction circuit that corrects the command signal based on the value. 10. The signal correction circuit according to claim 1, further comprising N-value input means which is manually operated, and which is capable of giving an N-value corresponding to the driving depth of the pile. A control device for a vibrating force in a pile driving work according to claim 9. 11. A vibration signal generating circuit for providing a vibration signal to a signal vibration transmitter mounted on an exciter or a pile, and a tip of the pile is positioned based on a reception signal from a receiver mounted on the pile. 10. An N-value calculation circuit for calculating an N value of an existing formation, wherein an output of the N-value calculation circuit is provided to the signal correction circuit. Vibration force control device for pile driving.