JPH0742694B2 - Ground improvement method and ground improvement machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention ensures that, when forming an improved columnar body on a support ground in soft ground, the improved columnar body surely bottoms on a certain support ground. The present invention relates to a ground improvement method and a ground improvement machine that can be automatically controlled so as to be formed.

(Prior Art) As a conventional ground improvement machine, a stirring shaft having a stirring blade fixed to its tip is vertically adjusted along a leader, and the stirring shaft is rotationally driven by a rotary drive motor and a driving device such as a winch. The stirrer shaft is lowered by the stirrer, and after the stirrer has penetrated to a specified depth, the stirrer shaft is pulled up by the drive device while stirring with the stirrer blade and spraying the improving material such as cement from the tip end of the stirrer shaft. What forms the body is known.

In the ground improvement by this ground improvement machine, in order to effectively transfer the overlaid load acting on the improved column to the support ground, the tip of the stirring shaft that ejects the improvement material is surely extended to the support ground below the soft layer. It is necessary to form an improved columnar body that securely penetrates into the supporting ground by penetrating into the ground.

Therefore, the depth to the supporting ground is confirmed in advance by the preceding boring before ground improvement, and the depth is used as the penetration depth of the agitation shaft, and is uniformly applied to multiple improved columns to support the ground. From the method that is regarded as the bottom of the stirrer, or because the strength of the ground and the current value of the rotation drive motor of the stirring shaft are proportional, the worker can check the current value of A method has been used in which it is determined whether or not the ground has reached the supporting ground by monitoring the change with an ammeter, and the bottom of the supporting ground is individually judged according to the actual ground.

However, since the depth of the supporting ground below the soft ground layer is not always constant even at the same construction site, for example, the position obtained from the boring result indicated by the alternate long and short dash line in Fig. 1 is defined as the depth of the supporting ground surface. When an improved column is formed from that position by using it as a single purpose, the improved column may be formed in a state where it is floating in the soft ground layer in the part where the supporting ground surface is deeper, and the purpose of ground improvement may be achieved. On the contrary, if the supporting ground surface is shallower, the tip of the agitation shaft penetrates into the supporting ground, which may reduce the work efficiency or shorten the life of the agitating blade or the rotary drive motor or damage it. It was

In addition, when the operator visually judges the current value, it is difficult to read the current value accurately because the ammeter swings due to inertial force, and at which current value the tip of the stirring shaft bottoms on the support ground. Judgment as to whether or not there is individual difference depending on the worker,
There is a possibility that the ground strength of the supporting ground determined to have reached the bottom may vary, and the supporting strength required for the ground after the ground improvement construction cannot be expected.

Furthermore, in the case of using the ammeter described above, the suitability of the determination of the bottom of the ground directly affects the quality of ground improvement and may cause damage to machinery and equipment, which imposes an excessive mental burden on the operator who makes the determination. There was a risk of reducing the construction efficiency.

(Object of the invention) In view of the above situation, the present invention is capable of reliably and automatically detecting a supporting ground position having a predetermined strength, thereby making it possible to improve the ground with good and constant quality, and to carry out the construction thereof. It is an object of the present invention to provide a ground improvement method and a ground improvement machine that can improve efficiency.

(Structure of the Invention) A first invention of the present application is a ground improvement method using a ground improvement machine having a stirring shaft which is rotationally driven by a rotary drive motor and is vertically driven by a drive device, in which a rotary drive motor during rotational drive is used. Detects the current value, compares the detected value with the preset allowable current value of the rotary drive motor,
A signal is transmitted when the detected value is larger, and the drive device is stopped when the signal transmission integrated time, which is an integration of the transmitted signals, is longer than a preset time.

Further, a second invention of the present application is a ground improvement machine having a stirring shaft that is rotationally driven by a rotational drive motor and is driven up and down by a drive device, and a current for setting an allowable current value of the rotational drive motor during rotational drive. A value setter, a current value detector for detecting the current value of the rotary drive motor during rotary drive, and the set value of the current value and the detected value are compared, and a signal is sent if the detected value is larger. The current value comparison circuit that emits, a counter that integrates the signal generation time by the signal from this comparison circuit, a time value setter for setting the time value corresponding to the target ground strength in the ground, and the above counter The ground improvement machine is equipped with a time value comparison circuit that compares the integrated time value of the above and the time value set by the time value setting device and issues a stop signal to the above drive when the integrated time value is greater than the set time value. Are those that form.

In the above configuration, if the allowable current value determined from the mechanical capacity of the rotary drive motor and the time value for regulating the predetermined strength of the target support ground are set,
The stirring blade provided at the tip of the stirring shaft comes into contact with the supporting ground while rotating, and a load is applied to the rotation drive motor.
The detected current value exceeds the above set current value, and by comparing the integrated time value obtained by integrating the time that has exceeded the set current value with the set time value, it is possible to detect the supporting ground position with a certain strength, and thereby the target support It is possible to easily form an improved columnar body that surely landed on the ground.

(Embodiment) FIG. 1 shows a state in which an improved columnar body is formed by using a ground improvement machine which is an embodiment of the present invention, and FIG. 2 shows a block diagram of a main part of the present invention.

The ground improvement machine shown in FIG. 1 is equipped with a reader 2 and a stirring shaft 4 having a stirring blade 3 at the tip end of a base machine 1, and a rotary drive motor 5 for rotating the stirring shaft 4.
Similarly, a drive device 6 for raising and lowering is provided, and a hose 7 from an improvement material plant (not shown) is connected to the upper end of the stirring shaft 4 via a swivel joint 8 to form a basic configuration.

Then, as shown in FIG.
A supporting ground position detecting device A is provided which detects the position of the supporting ground by the current value and controls the drive stop of the drive device 6.

This support ground position detecting device A includes a current value setter 9 for setting an allowable current value of the rotary drive motor 5, a current value detector 10 of the rotary drive motor 5 during rotary drive, a set current value and detection. A current value comparison circuit 11 that compares the current value and issues a pulse signal when the detected current value is larger, a time counter 12 that starts time integration by the signal of this comparison circuit 11, and a target time value The time value setter 13 for setting the time value is compared with the integrated time value in the time counter 12 and the set time value in the time value setter 13, and when the integrated time value is larger than the set time value, the above This is provided with a time value comparison circuit 14 which issues a stop signal to the drive device 6.

Here, the allowable current value set in the current value setter 9 is a value determined by the mechanical capacity of the rotary drive motor 5, for example, a current value corresponding to 100% torque of the rotary drive motor 5, and the current value The signal issued by the comparison circuit 11 turns on the time counter 12 only while the detected current value exceeds the set current value.
It is what makes the state.

The time value set in the time value setter 13 is a value determined by the strength of the target support ground, and the stop signal to the driving device 6 generated by the time value comparing circuit 14 is manually set by the driving device. Even when it is controlled, it preferentially acts on the drive device 6 to stop its drive.

When the stirring blade 3 is rotated by using this ground improvement machine to penetrate the stirring shaft 4 while stirring the soft ground, the rotation resistance acting on the stirring blade 3 changes depending on the strength of the ground, and As a result, the load acting on the rotary drive motor 5 changes.

By grasping this change in the strength of the ground as a change in the value of the current flowing through the rotary drive motor 5 and detecting this current value, it is possible to obtain a relative change in the strength of the ground, and The strength of a predetermined ground can be detected by making a comparison.

Then, as shown in FIG. 1, the rod-shaped stirring blade 3 provided at the tip of the stirring shaft 4 comes into contact with the convex and concave portions present on the upper surface of the hard supporting ground H below the soft ground layer S. Then, the detected current value suddenly increases and a signal is issued by the current value comparison circuit 11,
This continues until the stirring blade 3 scrapes off a part of the convex portion, and then the other adjoining stirring blade 3 rotates and comes into contact with the convex portion again to generate a signal.

In the meantime, the stirring shaft 4 descends, and the above contact and signal transmission are repeated intermittently, and finally, the signal is continuously emitted, and the improved columnar body P thus formed makes the top load effective. The position of the supporting ground is reached, which has a predetermined strength so that it can be transmitted to the supporting ground.

Therefore, by restricting the integrated value of the time when the signal is issued, that is, the integrated time value, the position of the supporting ground having a constant supporting strength can be determined even within the supporting ground that is the foundation on which the improved columnar P bottoms. Obtainable.

Then, when the integrated time value reaches the set time value, the drive device 6 that has lowered the stirring shaft 4 is automatically stopped, and the hose 7, the swivel joint 8 and the stirring shaft 4 are passed through the stirring shaft from the improvement material plant. While improving and agitating the improving material that has been pressure-fed to the discharge port of the tip portion, the stirring shaft 4 is pulled up to shift to the work of forming the improved columnar body P.

As a result, it is possible to form the improved columnar body P that is surely bottomed on the supporting ground having a certain strength according to the actual supporting ground.

Further, in the supporting ground position detecting device A of the present embodiment, means for limiting the integration of time by the time counter 12 by the position of the stirring blade 3, that is, the depth is added.

This is a hard formation S'on the surface layer near the surface of the soft ground S.
This is provided in order to prevent the current value of the rotary drive motor 5 from being increased by the hard formation S ′ in the case where there is an error, and the time counter 12 accumulates the current value as the time exceeding the allowable current value. .

The means for limiting the integration of this time are a depth detector 15 for detecting the depth of the stirring shaft 4 and a depth setter for setting the depth to be limited.
16 and a depth comparison circuit 17 that compares the detected depth with the set depth, and operates when the detected depth exceeds the set depth.
The electromagnetic relay 18 is turned on, and the normally open contact 19 of the electromagnetic relay is interposed between the current value comparison circuit 11 and the time counter 12.

The depth detector 15 can be variously applied in association with the vertical ascending / descending movement of the stirring shaft 4 or a driving device. As shown in FIG. 1, when a winch is used as a driving device and is driven up and down via a wire rope, For example, a depth detector is used that detects the vertical movement of the wire rope by converting it into a rotation angle and converts it into depth by an encoder using a pulse signal or a synchro signal.

As the depth set by the depth setter 16, for example, a depth at which the influence of the hard formation S'of the surface layer from the ground surface is eliminated may be set.

By adding such limiting means, the time counter 12 starts the integration of time after the influence of the hard ground layer S'is eliminated, so that the supporting ground H corresponding to the actual ground condition can be obtained. The position can be detected.

The display means indicated by 20 in FIG. 2 is, for example, a warning lamp for informing the operator that the stirring shaft has reached the target support ground,
The construction record output, which is also indicated by reference numeral 21 with a warning buzzer or the like, records the set current value, the set time value, the depth reaching the target supporting ground, and the like for each improved pillar.

In the present invention, the change in the strength of the ground is controlled by the rotary drive motor 5
Although it is considered as a change in the value of the current flowing through the ground, the power consumption value of the rotary drive motor 5 is used instead of this current value, and the change in the ground strength can be detected by detecting the change.

(Effect of the Invention) According to the ground improvement method and the ground improvement machine of the present invention, the allowable current value determined by the mechanical capacity of the rotary drive motor and the time value for controlling the predetermined strength targeted as the support ground. By simply setting and, the support ground position having a certain strength can be detected reliably, quickly, and automatically.

As a result, the mental burden on the operator in determining the bottom of the agitation shaft can be eliminated, the bottom determination can be made faster, and unnecessary penetration into the supporting ground is eliminated, improving the construction efficiency and reducing the consumption of improved materials. In addition, it is possible to form an improved columnar bottomed on a supporting ground that has a certain level of strength, depending on the actual supporting ground, so it is possible to improve the ground with good and constant quality. .

[Brief description of drawings]

FIG. 1 is a simplified explanatory view showing a construction state according to an embodiment of the present invention, and FIG. 2 is a block diagram of a main part of the present invention in the embodiment of FIG. A ... Support ground position detection device, S ... Soft ground, H ... Support ground, P ... Improved column, 3 ... Stirring blade, 4 ... Stirring shaft, 5 ... Rotation drive motor, 6 ... Drive device, 9 ... Current value setting Meter, 10 ... Current value detector, 11 ... Current value comparison circuit, 12 ... Time counter, 13 ... Time value setter, 14 ... Time value comparison circuit.

Claims (2)

[Claims] 1. A ground improvement method using a ground improvement machine having a stirring shaft which is rotationally driven by a rotary drive motor and is vertically moved by a drive device, wherein a current value of the rotary drive motor during rotary drive is detected, The detected value is compared with a preset allowable current value of the rotary drive motor, and when the detected value is larger, a signal is transmitted, and the signal transmission integrated time obtained by integrating the transmitted signal is set in advance. A method for improving the ground, characterized in that the driving device is stopped when the time is longer than the time. 2. A ground improvement machine having a stirring shaft which is rotationally driven by a rotational drive motor and is vertically moved by a drive device, and a current value setting device for setting an allowable current value of the rotational drive motor during rotational drive. , Current value detector for detecting the current value of the rotary drive motor during rotary drive, and the current value comparison that compares the set value of the current value with the detected value and issues a signal when the detected value is larger Circuit, a counter that integrates the signal generation time by the signal from this comparison circuit, a time value setter for setting the time value corresponding to the target ground strength in the ground, and the integrated time value in the counter And a time value comparison circuit for issuing a stop signal to the drive device when the integrated time value is larger than the set time value by comparing the time value setter with the time value setter. .