JP5775899B2 - Pile construction method using vibration pile punching machine - Google Patents

Description

  The present invention relates to a construction method in which a pile is driven or pulled out by a vibration pile punching machine equipped with a vibrator.

  In the construction of pile driving or drawing, a vibrating pile punching machine equipped with a vibrator is used. FIG. 10 is a side view schematically showing the main part of the exciter in order to show the operating principle of the exciter. A biaxial vibrator 2 is shown as an example. The drive shaft 21 is rotationally driven by a motor M provided in the vibrator 2. The motor M may be a hydraulic motor or an electric motor. The driven shaft 22 is transmitted with the rotation of the drive shaft 21 through a gear 27. Fixed eccentric weights 23 and 25 that rotate together with the shaft and movable eccentric weights 24 and 26 that are not fixed to the shaft are attached to the drive shaft 21 and the driven shaft 22, respectively. The relative phases of the fixed eccentric weights 23 and 25 and the movable eccentric weights 24 and 26 can be changed by a phase adjuster 2a attached to the driven shaft 22 and hydraulically controlled. By changing the relative phases of the fixed eccentric weights 23 and 25 and the movable eccentric weights 24 and 26, the eccentric moment of the entire exciter 2 is changed from zero shown in (a) to the maximum shown in (b). Is possible. The phase adjuster 2a can change the phase even while the exciter 2 is rotating (Patent Documents 1 and 2).

  FIG. 11 is a diagram schematically showing how each parameter changes when a pile is driven using a conventional vibration pile punching machine. The vertical axis represents the depth of the target ground, and the horizontal axis represents each parameter. An example of the ground consisting of a plurality of layers having different hardness is shown on the leftmost side. (A) is the N value of the target ground measured by the boring test, (b) is the load factor of the motor of the exciter, (c) is the eccentric moment of the exciter, and (d) is the output of the drive source.

  In this specification, the “drive source” is an energy supply source that supplies energy to the motor M of the exciter shown in FIG. When the motor M of the exciter is a hydraulic motor, the drive source is usually an engine that rotationally drives a hydraulic pump that pumps oil to the hydraulic motor. When the motor M is an electric motor, the drive source is usually a generator (typically a generator) that supplies electric power for rotationally driving the electric motor.

  Further, in this specification, the “motor load factor” or “load factor” is a ratio of the actual load of the motor when the rated load of the motor is 100%. As shown in (a), the N value of the target ground gradually increases from the soft layer to the intermediate layer and from the support layer. And as shown to (b), if a motor load factor is measured at the time of driving of a pile, it will change substantially corresponding to N value. This is because the resistance force of the soil applied to the pile at the time of driving changes corresponding to the N value of the target ground. The motor load factor is measured by hydraulic pressure in the case of a hydraulic motor, and is measured by a current value (voltage is substantially constant) in the case of an electric motor.

  Conventionally, when the eccentric moment of the vibrator 2 shown in FIG. 10 can be adjusted, after adjusting to the maximum eccentric moment necessary for driving the hardest part of the target ground, the adjusted maximum eccentric moment is obtained. Construction was performed after fixing. For example, when it is considered that the maximum eccentric moment is required in the support layer, as shown in (c), driving is performed with the eccentric moment being maximized from the start of driving.

  Therefore, the drive source was also constructed after being fixed in accordance with the maximum required output. For example, when it is considered that the rated output is necessary in the support layer, the operation is performed at the rated output from the start of driving as shown in (d). As a result, the fuel consumption of the engine or generator as the drive source was also consumed at the rated output from the time of driving to the completion of driving.

Japanese Patent No. 2012-7315 JP 2012-52363 A

  However, since the motor load factor of the exciter remains low when the target ground is soft and the N value is low, useless fuel is consumed when the drive source is always operated at the maximum output. It will be.

  In view of the above situation, the present invention optimally adjusts the eccentric moment of the exciter according to the resistance force received by the pile from the target ground so that the fuel of the drive source of the vibration pile punching machine is not wasted. An object is to provide a method for driving or drawing a pile.

In order to achieve the above object, the present invention provides the following configuration.
In one aspect of the present invention, a phase adjuster that adjusts the relative phases of a fixed eccentric weight and a movable eccentric weight attached to each of a plurality of rotation shafts including a drive shaft that is rotationally driven by a motor is provided. In a construction method for driving or pulling out a pile using a vibrating pile punching machine equipped with a vibrator, the step of measuring in advance the relationship between the depth of the target ground and the change in N value prior to driving or pulling out the pile; The phase prior to driving or pulling the pile so that the eccentric moment by the fixed eccentric weight and the movable eccentric weight of the exciter during driving or pulling of the pile changes according to the change of the N value measured in advance. Presetting the phase adjustment pattern by the adjuster;
The process of continuously detecting the motor load factor of the motor that changes substantially corresponding to the N value of the target ground during driving or pulling out of the pile, and the detected N change of the motor load factor and the previously measured N value A step of monitoring whether or not the respective trends of the changes in the values match within a predetermined allowable range, and the respective trends of the change in the motor load factor and the change in the N value measured in advance are within the predetermined allowable range , The step of driving or pulling out the pile while adjusting the phase by the phase adjuster according to the set adjustment pattern , the change in the motor load factor and the change in the N value measured in advance In the case where the respective tendencies do not match within a predetermined allowable range, the phase adjuster adjusts the phase so that the eccentric moment changes according to the tendency of the motor load factor to change. And having a step for implantation or extraction of the pile, the.

If the motor in the embodiment described above is a hydraulic motor, by detecting the oil pressure of the hydraulic motor, it is suitable for detecting the motor load factor.

If the motor in the embodiment described above is an electric motor, by detecting the current value of the electric motor, it is suitable for detecting the motor load factor.

  The present invention has been made paying attention to the fact that the motor load factor of the vibrator in the vibration pile punching machine substantially corresponds to the N value of the target ground. When driving or pulling out the pile, it is performed while measuring the motor load factor, and the eccentric moment of the exciter can be adjusted according to the motor load factor. Furthermore, the N value of the target ground is measured in advance, the eccentric moment of the exciter is set in advance according to the motor load factor assumed from the measured N value, and the pile is driven or pulled out while adjusting the eccentric moment according to the setting It can be performed. Thereby, the fuel consumption of a drive source can be suppressed to the necessary minimum. As a result, it is possible to suppress the fuel consumption of the drive source that has conventionally been operated in accordance with the maximum required eccentric moment in all processes to the minimum necessary.

FIG. 1 is a diagram schematically showing a configuration of a main part that performs a driving or drawing operation in a vibration pile punching machine. FIG. 2 is a diagram schematically showing the overall configuration of the vibration pile punching machine when the motor of the vibrator shown in FIG. 1 is a hydraulic motor. FIG. 3 is a diagram schematically showing the overall configuration of the vibration pile punching machine when the motor of the vibrator shown in FIG. 1 is an electric motor. FIG. 4 is a diagram schematically illustrating an example in which the eccentric moment is sequentially controlled according to the motor load factor when driving the pile. FIG. 5 is a diagram illustrating an example of a method for controlling the eccentric moment at the time of driving a pile when the target ground changes from viscous soil, sandy soil, and rock. FIG. 6 is a diagram illustrating an example of a method for controlling the eccentric moment at the time of pile driving when the target ground is substantially sandy soil. FIG. 7 is a diagram illustrating an example of a method of controlling the eccentric moment when driving a pile when the target ground is substantially rock. FIG. 8 is a diagram illustrating an example of a method for controlling the eccentric moment at the time of pulling out the pile when the target ground changes to viscous soil, sandy soil, and rock. FIG. 9 is a flow diagram showing an example of a pile driving or drawing construction flow to which the control method of the present invention is applied. FIG. 10 is a side view schematically showing the main part of the exciter in order to show the operating principle of the exciter. FIG. 11 is a diagram schematically showing how each parameter changes when a pile is driven using a conventional vibration pile punching machine.

Embodiments of the present invention will be described below with reference to the drawings showing application examples of the present invention.
FIG. 1 is a diagram schematically showing a configuration of a main part that performs a driving or drawing operation in a vibration pile punching machine. The main part of the vibration pile punching machine 1 is provided with a vibration generator 2 and a pile gripping device 3. The vibrator 2 is suspended by a crane or the like. The vibrator 2 includes a motor that rotationally drives the eccentric weight shown in FIG. 10 described above. The motor is a hydraulic motor Mo or an electric motor Me. The pile gripping device 3 is attached to the lower end of the vibrator 2. The pile gripping device 3 grips the head of a pile 50 such as a steel pipe pile or a steel sheet pile. With the pile gripping device 3 gripping the pile 50 at a specified pressure, the vibrator 50 is driven to rotate by the hydraulic motor Mo or the electric motor Me, so that the pile 50 is driven into the target ground or pulled out from the target ground. Do work.

  FIG. 2 is a diagram schematically showing the overall configuration of the vibration pile punching machine when the motor of the vibrator 2 shown in FIG. 1 is a hydraulic motor Mo. In FIG. 2, a thick line with an arrow indicates an oil path. A dotted line indicates a main one of the detection signal or the control signal.

  As shown in FIG. 2, the hydraulic circuit is configured to pump the oil in the oil tank T to a target hydraulic device by an appropriate pump and return it to the oil tank T again. Oil is pumped from the hydraulic motor pump P <b> 1 to the hydraulic motor Mo of the vibrator 2. Oil is pumped from the phase adjuster pump P2 to the phase adjuster 2a of the vibrator 2. Oil is pumped from the gripping pump P3 to the hydraulic cylinder 3a of the pile gripping device 3.

  The switching valve 3b on the oil passage of the pile gripping device 3 switches whether the oil from the gripping pump P3 is sent to the hydraulic cylinder 3a or returned to the oil tank T as it is. The pressure switch 3d on the oil passage of the pile gripping device 2 outputs a function of a pressure gauge for detecting the pressure of the hydraulic cylinder 3a, that is, the gripping pressure of the pile gripping device 3, and a signal corresponding to the detected gripping pressure to the control unit 4A. With functionality. The pressure switch 3d always functions from the start to the end of the vibration pile punching machine.

  The engine Eo as a drive source drives the hydraulic motor pump P1, the phase adjuster pump P2, and the gripping pump P3 in parallel. The hydraulic motor pump P1 and the gripping pump P2 rotate at the same rotational speed as that of the motor Eo, or rotate at a predetermined ratio through a gear or a pulley.

  The control unit 4A includes an electronic circuit that controls the operation of the vibration pile punching machine, and is also connected to an operation panel (not shown) for manual operation. The electronic circuit preferably includes a microprocessor and executes the control program according to the invention. The main control signal transmitted by the control unit 4A is to the exciter pump P1 (or the switching valve on the oil passage), the phase adjuster pump P2 (or the switching valve on the oil passage), the gripping pump P3 or the switching valve 3b. Sent. The main detection signals received by the control unit 4A are a signal indicating the hydraulic pressure of the hydraulic motor Mo and a signal indicating the gripping pressure sent from the pressure switch 3d.

  Functions included in the control program of the control unit 4A include at least a motor control unit 4a, a hydraulic motor control unit 4b, a gripping pressure detection unit 4c, a gripping pressure control unit 4d, a motor oil pressure detection unit 4e, an eccentric moment control unit 4f, An operation mode switching unit 4g is provided.

  The motor control unit 4a controls the operation of the motor Eo, and can set the rotation speed in a range from zero in a stopped state to a specified rotation speed at which a pile is driven or pulled out.

  The hydraulic motor control unit 4b controls connection or disconnection of the hydraulic motor pump P1 with respect to the engine Eo. After the rotational speed of the motor Eo reaches the specified rotational speed, when the hydraulic motor pump P1 is connected to the motor Eo, oil is pumped to the hydraulic motor Mo, the hydraulic motor Mo is activated, and the vibrator is driven to rotate. Is done. The hydraulic motor Mo can be operated after a “grip completion” signal is sent from the gripping pressure control unit 4d.

  The gripping pressure detector 4c receives a detection signal indicating the gripping pressure detected by the pressure switch 3d and passes it to the gripping pressure controller 4d. The gripping pressure control unit 4d controls the operation of the switching valve 3b. By switching the switching valve 3b to the hydraulic cylinder 3a of the pile gripping device 3, the pile gripping device 3 is opened and closed. When the gripping pressure of the pile reaches a predetermined value and the gripping of the pile is completed, the gripping pressure control unit 4d sends a signal “completion of gripping” to the hydraulic motor control unit 4b.

  The motor hydraulic pressure detection unit 4e receives a detection signal indicating the hydraulic pressure of the hydraulic motor Mo during operation of the hydraulic motor Mo, that is, when the pile is driven or pulled out, and passes the detection signal to the eccentric moment control unit 4f. The hydraulic pressure of the hydraulic motor Mo represents the load factor of the hydraulic motor Mo, and this motor load factor reflects the resistance force that the pile receives from the target ground.

  The eccentric moment control unit 4f controls the phase adjuster pump P2 based on the oil pressure detected by the motor oil pressure detecting unit 4e to pump or suck oil to the phase adjuster 2a. The phase adjuster 2a is controlled. As a result, the eccentric moment of the exciter changes (see FIG. 10 described above). When the detected oil pressure increases, the phase adjuster 2a is controlled to increase the eccentric moment of the exciter and increase the amplitude and the excitation force of the exciter. As a result, the output of the vibration pile punching machine, that is, the output of the motor Eo increases (the hydraulic pressure of the hydraulic motor pump P1 increases. The hydraulic pressure is substantially constant), and the combustion consumption increases. On the other hand, when the detected oil pressure becomes low, the eccentric moment of the exciter is reduced, and the amplitude and the excitation force of the exciter are reduced. As a result, the output of the vibration pile punching machine, that is, the output of the motor Eo is reduced (the hydraulic pressure of the hydraulic motor pump P1 is lowered. The hydraulic pressure is substantially constant), and the combustion consumption is reduced.

  The operation mode switching unit 4g switches between a plurality of operation modes. For example, an operation mode to which the control method according to the present invention is applied and a manual operation mode are switched. Alternatively, switching between the respective operation modes to which a plurality of different control methods according to the present invention described later is applied is performed.

  FIG. 3 is a diagram schematically showing the overall configuration of the vibration pile punching machine when the motor of the vibrator 2 shown in FIG. 1 is an electric motor Me. Note that portions common to the configuration using the hydraulic motor Mo in FIG. 2 are denoted by the same reference numerals, and the description may be simplified or omitted.

  As shown in FIG. 3, the hydraulic circuit of the phase adjuster 2a and the phase adjuster pump P2 of the vibrator 2, and the hydraulic cylinder 3a of the pile gripping device 3 and the hydraulic circuit of the gripping pump P3 are shown in FIG. Same as the configuration.

  In the configuration of FIG. 3, the drive source of the electric motor Me of the vibrator 2 is the generator generator Ee. The generator / generator Ee rotates the rotational power source with a predetermined fuel to generate power by the generator, and outputs electric power.

  The generator / generator Ee, which is a driving source, directly drives the electric motor Me to rotate at a predetermined specified rotational speed. At the specified rotational speed, the voltage of the generator / generator Ee is substantially constant, but the current varies depending on the motor load factor of the electric motor Me.

  In this configuration example, the generator / generator Ee also outputs power to each pump electric motor that drives the phase adjuster pump P2 and the gripping pump P3. The phase adjuster pump P2 and the gripping pump P3 are controlled to rotate at a predetermined rotational speed.

  The control unit 4B includes an electronic circuit that controls the operation of the vibration pile punching machine, and is also connected to an operation panel (not shown) for manual operation. The electronic circuit preferably includes a microprocessor and executes the control program according to the invention. Main control signals transmitted by the control unit 4B are sent to the generator / generator Ee, the phase adjuster pump P2, the switching valve 3b of the gripping pump P3, and the like. The main detection signals received by the control unit 4B are a signal indicating the current value of the electric motor Me and a signal indicating the gripping pressure sent from the pressure switch 3d.

  The functions included in the control program of the control unit 4B include at least the generator generator control unit 4h, the electric motor control unit 4i, the gripping pressure detection unit 4c, the gripping pressure control unit 4d, the motor current value detection unit 4j, and the eccentric moment control unit 4f. An operation mode switching unit 4g is provided.

  The generator / generator control unit 4h can control the output voltage of the generator / generator Ee to set the number of rotations of the electric motor Me from zero in a stopped state to a specified number of rotations for driving or pulling out a pile. It is.

  The electric motor control unit 4i controls connection or disconnection of the electric motor Me to the generator / generator Ee. After the output voltage of the generator / generator Ee reaches a value corresponding to the specified rotational speed, when the electric motor Me is connected to the generator / generator Ee, the electric motor Me is actuated and the vibrator is rotationally driven. The electric motor Me can be operated after a “grip completion” signal is sent from the gripping pressure control unit 4d.

  The gripping pressure detector 4c receives a detection signal indicating the gripping pressure detected by the pressure switch 3d and passes it to the gripping pressure controller 4d. The gripping pressure control unit 4d controls the operation of the switching valve 3b. By switching the switching valve 3b to the hydraulic cylinder 3a of the pile gripping device 3, the pile gripping device 3 is opened and closed. When the gripping pressure of the pile reaches a predetermined value and the gripping of the pile is completed, the gripping pressure control unit 4d sends a signal “completion of gripping” to the electric motor control unit 4i.

  The motor current value detection unit 4j receives a detection signal indicating the current value of the electric motor Me during operation of the electric motor Me, that is, when the pile is driven or pulled out, and passes it to the eccentric moment control unit 4f. The current value of the electric motor Me represents the load factor of the electric motor Me, and this motor load factor reflects the resistance force that the pile receives from the target ground.

  The eccentric moment control unit 4f controls the phase adjuster pump P2 based on the current value detected by the motor current value detecting unit 4j, and pumps or sucks oil to the phase adjuster 2a. The phase adjuster 2a is controlled. As a result, the eccentric moment of the exciter changes (see FIG. 10 described above). When the detected current value becomes high, the phase adjuster 2a is controlled to increase the eccentric moment of the exciter and increase the amplitude and the excitation force of the exciter. As a result, the output of the vibration pile punching machine, that is, the output current of the generator / generator Ee increases (the output voltage is basically substantially constant), and the combustion consumption increases. On the other hand, when the current value becomes low, the eccentric moment of the exciter is reduced, and the amplitude and the excitation force of the exciter are reduced. As a result, the output of the vibration pile punching machine, that is, the output current of the motor generator Ee is reduced (the output voltage is basically substantially constant), and the combustion consumption is reduced.

  The operation mode switching unit 4g switches between a plurality of operation modes. For example, an operation mode to which the control method according to the present invention is applied and a manual operation mode are switched. Alternatively, switching between the respective operation modes to which a plurality of different control methods according to the present invention described later is applied is performed.

Regardless of whether the exciter motor is a hydraulic motor or an electric motor, the output of the vibration pile punching machine is expressed by the following equation.
Output of vibration pile punching machine = excitation force x amplitude x resistance coefficient In the above equation, the resistance coefficient is determined by the nature of the target ground. The excitation force is proportional to the eccentric moment and the square of the angular velocity. The amplitude is proportional to the eccentric moment. Since the rotational speed of the motor of the exciter during driving or drawing is substantially constant, the angular velocity is substantially constant. Therefore, by changing the eccentric moment, the excitation force and the amplitude change, and as a result, the output of the vibration pile punching machine changes. The change in the output of the vibration pile punching machine is the change in the output of the power source that is the motor Eo or the motor generator Ee of FIG. 2 or FIG. As a result, the fuel consumption in the power source changes.

  Hereinafter, with reference to FIGS. 4-9, the example of the control method of the vibration pile punching machine to which this invention is applied is shown.

  FIG. 4 is a diagram schematically illustrating an example in which the eccentric moment is sequentially controlled according to the motor load factor when driving the pile. The vertical axis represents the depth of the target ground, and the horizontal axis represents each parameter. An example of the ground consisting of a plurality of layers having different hardness is shown on the leftmost side. (A) is the motor load factor of the vibrator during driving, (b) is the eccentric moment of the vibrator, and (c) is the output of the drive source. The dotted lines in (b) and (c) indicate the maximum eccentric moment and the rated output of the drive source, respectively (the same applies to the following figures).

  When the target ground becomes hard soil as the depth increases with the soft layer, intermediate layer and support layer, the motor load factor is almost zero at the start of driving, and the peripheral friction resistance of the pile as the depth increases with the same soil quality The force increases and the motor load factor gradually increases. The load factor may increase discontinuously at the boundary where soil quality changes. In the example of FIG. 4, during the driving of the pile, the motor load factor is continuously detected as shown in (a). And as shown in (b), simultaneously with the detection of the motor load factor, the eccentric moment is changed according to the tendency of the change of the detected motor load factor. This is performed by continuously adjusting the relative phases of the fixed eccentric weight and the movable eccentric weight of the exciter with the phase adjuster. As a result, as shown in (c), the output of the drive source changes, that is, the fuel consumption changes. Compared with the conventional example of FIG. 11, the drive source need not always be operated at the rated output, so the fuel consumption can be greatly reduced.

  Although FIG. 4 shows an example when driving a pile, even when a pile is pulled out, the motor load factor may be continuously detected and the eccentric moment may be sequentially controlled according to the motor load factor. . Although not shown, when the pile is pulled out, the peripheral frictional resistance of the pile is maximum until the bond between the soil and the pile is cut at the beginning of extraction, and during the extraction, the peripheral frictional resistance gradually decreases, and the motor load The rate gradually decreases. The motor load factor becomes almost zero when drawing is nearing completion.

  5 to 9 show an example of a control method for presetting a control pattern of the eccentric moment based on the N value of the target ground measured in advance.

  FIG. 5 is a diagram illustrating an example of a method for controlling the eccentric moment during pile driving when the target ground becomes hard soil as the depth increases with the soft layer, the intermediate layer, and the support layer. (A) is an N value measured in advance, (b) is a motor load factor of the exciter during driving, (c) is an eccentric moment of the exciter (set value and control value during actual driving), (d ) Is the output of the drive source.

  First, prior to construction, the relationship between the depth of the target ground and the change in the N value is measured as shown in (a). This measurement is performed by a standard penetration test. Next, based on the relationship between the measured depth and the change in the N value, a control pattern of the eccentric moment of the exciter during pile driving is set in advance as shown in FIG. That is, an adjustment pattern of the relative phase of both eccentric weights by the phase adjuster is set in advance. For example, the value of the eccentric moment is set to a predetermined value in the range of 65 to 70% at the maximum in the soft layer, the predetermined value in the range of 70 to 80% at the maximum in the intermediate layer, and the maximum in the support layer. A predetermined value of 80 to 100% is set. Then, the pile is driven while controlling the eccentric moment according to the set adjustment pattern.

  Furthermore, it is preferable to continuously detect the motor load factor as shown in FIG. This is to monitor whether or not the tendency of the actually detected change in the motor load factor and the change in the N value measured in advance coincide with each other within a predetermined allowable range. Since the measurement of the N value is usually performed by a boring survey at only one place, it does not always completely match the N value at the place where the pile is actually hit. Although it is likely that they have almost the same tendency, they may be locally different. The allowable range that can be regarded as matching is set as appropriate according to the construction conditions.

  If the detected change in the motor load factor and the tendency of the change in the N value measured in advance match within the predetermined tolerance, the eccentric moment is controlled according to the set adjustment pattern, and the pile driving is completed. To do. FIG. 5C shows a set value of the eccentric moment and a control value during actual driving. As a result, as shown in (d), the output of the drive source changes, that is, the fuel consumption changes.

  FIG. 6 is a diagram illustrating an example of a method for controlling the eccentric moment during pile driving when the target ground is soft ground. (A) is a pre-measured N value, (b) is the motor load factor of the exciter during driving, (c) is the eccentric moment of the exciter (during actual driving), and (d) is the output of the drive source. It is.

  In this example, the N value measured prior to construction is a relatively small value and substantially constant as shown in (a). Based on this measurement result, the control pattern of the eccentric moment of the exciter during driving of the pile is set to be maintained at a maximum constant value of 50% prior to driving of the pile.

  Pile driving is started, and the motor load factor is continuously detected as shown in FIG. In this case, it is detected that the motor load factor has increased in the depth range indicated by reference numeral D1 in (b), and the degree of this increase exceeds a predetermined allowable range. In that case, as shown in (c), the eccentric moment is made larger than the set value. For example, the phases of both eccentric weights are adjusted by the phase adjuster so that the eccentric moment becomes the maximum 70%. When the motor load factor returns to within the assumed range again, the eccentric moment is also returned to the original set value. As a result, as shown in (d), the output of the drive source changes, that is, the fuel consumption changes.

  FIG. 7 is a diagram illustrating an example of a method of controlling the eccentric moment when driving a pile when the target ground is hard ground. (A) is a pre-measured N value, (b) is the motor load factor of the exciter during driving, (c) is the eccentric moment of the exciter (during actual driving), and (d) is the output of the drive source. It is.

  In this example, the N value measured prior to construction is a relatively large value and substantially constant as shown in FIG. Based on the measurement result, the control pattern of the eccentric moment of the exciter during the driving of the pile is set to be maintained at a constant value within the maximum range of 70 to 80% prior to the driving of the pile.

  Pile driving is started, and the motor load factor is continuously detected as shown in FIG. In this case, it is detected that the motor load factor has decreased in the depth range indicated by reference numeral D2 in (b), and the degree of this decrease exceeds a predetermined allowable range. In that case, as shown in (c), the eccentric moment is made smaller than the set value. For example, the phases of both eccentric weights are adjusted by the phase adjuster so that the eccentric moment becomes 50% at the maximum. When the motor load factor returns to within the assumed range again, the eccentric moment is also returned to the original set value. As a result, as shown in (d), the output of the drive source changes, that is, the fuel consumption changes.

  In addition, although FIG. 5-7 mentioned above is an example at the time of pile driving, similarly at the time of pile extraction, N value of a target ground is similarly measured beforehand, and both of exciters are based on the measured N value. The phase adjustment of the eccentric weight may be set, and the extraction may be performed while controlling the eccentric moment by changing the phases of both eccentric weights according to the set adjustment pattern. Then, it continuously detects changes in the motor load factor during drawing, and responds to changes in the motor load factor when the motor load factor increases or decreases beyond the allowable range of change assumed from the measured N value. The eccentric moment is increased or decreased from the set value by adjusting the phases of the two eccentric weights.

  FIG. 8 is a diagram illustrating an example of a method for controlling the eccentric moment at the time of pulling out the pile when the target ground includes a soft layer, an intermediate layer, and a support layer. (A) is a pre-measured N value, (b) is the motor load factor of the exciter during extraction, (c) is the eccentric moment of the exciter (during actual extraction), and (d) is the output of the drive source. It is. In this case, for example, the value of the eccentric moment is set to a predetermined value in the maximum 75% range in the support layer, the predetermined value in the maximum 50% range in the intermediate layer, and the maximum 25 in the soft layer. Set to a predetermined value of%. At the time of actual drawing, if the motor load factor becomes almost zero nearing completion of drawing, the eccentric moment may be zero at that time. In that case, the drive source is in an idling state.

  FIG. 9 is a flow diagram showing an example of a pile driving or drawing construction flow to which the control method of the present invention is applied.

  First, the relationship between the depth of the target ground and the change in the N value is measured before construction (step S01). Next, a motor load factor at a predetermined depth is assumed based on the measured N value. Assume that the relationship between the N value and the motor load factor of a motor having a predetermined rated load is obtained empirically. The value of the eccentric moment of the exciter at the predetermined depth is set in advance so as to correspond to the assumed motor load factor at the predetermined depth. That is, an adjustment pattern of the eccentric moment by the phase adjuster in the entire depth range of construction is set in advance (step S02).

  In actual construction, in the case of pile driving, first, the pile is suspended and built (step S03). This is not the case for pulling out piles. Subsequently, the vibratory hammer is suspended and the vibratory hammer is placed on the head of the pile (step S04).

  A drive source (engine or engine generator) is started to be in an idling state (step S04).

  Pile gripping is completed by operating the pile gripping device and gripping the pile with a predetermined gripping pressure (step S04). As a result, the motor of the exciter can be driven.

  Driving of the motor of the exciter is started, and driving or drawing of the pile is started with the set eccentric moment while detecting the motor load factor (step S07).

  During driving or drawing, it is monitored whether or not the motor load factor is a value within an allowable range based on an N value measured in advance (step S08). If the change amount of the motor load factor is within the assumed allowable range, the control of the eccentric moment according to the set value is maintained (step S09). When the change amount of the motor load factor increases beyond the allowable range, the phase adjustment of the two eccentric weights is performed by the phase adjuster so as to increase the eccentric moment beyond the set value (step S10). When the amount of change in the motor load factor decreases beyond the allowable range, the phase adjustment of the two eccentric weights is performed by the phase adjuster so as to decrease the eccentric moment below the set value (step S11). The adjustment amount in step S10 and step S11 is an appropriate amount according to the change amount of the motor load factor.

  When the final depth is reached in pile driving, or when the motor load factor is zero, that is, in the idling state in pile drawing, the motor is disconnected from the driving source, and the driving source is set in an idling state (step S12).

  Thereafter, the pile holding device is operated to open the pile (step S13). Finally, the drive source is stopped (step S14).

DESCRIPTION OF SYMBOLS 1 Vibration pile punching machine 2 Excitation machine 2a Phase adjuster P1 Hydraulic motor pump P2 Phase adjuster pump P3 Grasping pump 21 Drive shaft 22 Drive shaft 23, 25 Fixed eccentric weight 24, 26 Movable eccentric weight 3 Pile grip Device 4 Control unit Mo Hydraulic motor Me Electric motor Eo Motor Ee Motor generator 50 Pile

Claims (3)

Vibration provided with an exciter including a phase adjuster for adjusting the relative phase of a fixed eccentric weight and a movable eccentric weight attached to each of a plurality of rotation shafts including a drive shaft that is rotationally driven by a motor In the construction method of driving or pulling piles using a pile punching machine,
A step of measuring in advance the relationship between the depth of the target ground and the change in the N value prior to driving or pulling out the pile;
The phase adjustment prior to driving or pulling the pile so that the eccentric moment by the fixed eccentric weight and movable eccentric weight of the exciter during driving or pulling of the pile changes according to the change of the N value measured in advance. Presetting the phase adjustment pattern by the instrument;
A step of continuously detecting the motor load factor of the motor that changes substantially corresponding to the N value of the target ground during driving or drawing of the pile;
Monitoring whether the detected change in the motor load factor and the tendency of the change in the N value measured in advance coincide with each other within a predetermined allowable range;
When the tendency of the change of the motor load factor and the change of the N value measured in advance coincide with each other within a predetermined allowable range, the phase adjuster adjusts the phase according to the set adjustment pattern. A process of driving or pulling a pile;
When the respective trends of the change in the motor load factor and the change in the N value measured in advance do not coincide with each other within a predetermined allowable range, the eccentric moment changes according to the tendency of the change in the motor load factor. And a step of driving or pulling out the pile by adjusting the phase by the phase adjuster, and a method for constructing a pile by a vibration pile punching machine. If the motor is a hydraulic motor, by detecting the oil pressure of the hydraulic motor, the construction method of the pile by vibration pile punching machine according to claim 1, characterized in that for detecting the motor load factor. If the motor is an electric motor, by detecting the current value of the electric motor, the construction method of the pile by vibration pile punching machine according to claim 1, characterized in that for detecting the motor load factor.

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