JPH0742695B2 - Ground improvement method and ground improvement machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is such that, when forming an improved columnar body on a support ground in soft ground, the improved 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 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 reaches the support ground. There is a possibility that the strength required for the ground after the ground improvement work cannot be expected due to the difference in the strength of the supporting ground that was judged to have bottomed out, depending on the individual operator who made the judgment. .

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,
When the detected value exceeds a set value, a signal is transmitted and the excess current value is obtained, and the excess electricity amount is obtained from the excess time and the excess current value obtained by integrating the signal transmission time, The drive device is stopped when the accumulated excess electricity amount obtained by integrating the excess electricity amount is larger than a preset set electricity amount.

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 rotation drive, and comparing the set value of the current value with the detected value, and when the detected value exceeds the set value, A current value comparison circuit that emits a signal, a time calculation means that receives a signal from this comparison circuit and counts the signal generation time to obtain an excess time, and a set value from the detected value when the signal is generated in the comparison circuit. A current value calculator for subtracting the excess current value, and an excess electricity amount calculated from the excess current value obtained by the current value calculator and the excess time obtained by the time counting means, and the excess electricity amount is integrated. Electric quantity calculator, the electric quantity setter for setting the value of the electric quantity corresponding to the target ground strength in the ground, and the accumulated excess electric quantity and the electric quantity setter in the above electric quantity calculator The ground improvement machine is configured with a quantity-of-electricity comparison circuit that compares the quantity of electricity to be set and issues a stop signal to the drive device when the accumulated quantity of excess electricity is larger than the quantity of electricity to be set.

In the above configuration, if the allowable current value determined from the mechanical capacity of the rotary drive motor and the value of the amount of electricity for restricting the predetermined strength of the target support ground are set, the stirring shaft As the stirring blade provided at the tip contacts the supporting ground while rotating, a load is applied to the rotary drive motor, the detected current value exceeds the set current value, and the excess time and excess current value By calculating the amount of electricity and comparing the accumulated excess electricity amount by integrating the excess electricity amount with the above set electricity amount, it is possible to detect the support ground position with a certain strength, and thereby reliably land on the target support ground. The improved columnar body can be easily formed.

(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 first current value comparison circuit 11 that compares the current value and issues a signal when the detected current value is larger, and a time counter that counts the signal generation time by the signal of this comparison circuit 11 and obtains the excess time. 12, a current value calculator 13 that calculates the excess current value by subtracting the set value from the detected current value, and a second current value comparison circuit that determines the positive or negative of the excess current value calculated by this current value calculator 13. 14, the electricity amount calculator 15 for obtaining and integrating the excess electricity amount from the excess current value input when the second current value comparison circuit 14 is positive and the excess time obtained by the time counter 12, and the target. And the electric quantity setter 16 for setting the value of the electric quantity corresponding to the ground , The accumulated excess electricity amount in the electricity amount calculator 15 is compared with the set electricity amount in the electricity amount setting device 16, and when the accumulated excess electricity amount is larger than the set electricity amount, a stop signal is sent to the drive device 6. It is provided with a quantity-of-electricity comparison circuit 17 to be emitted.

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 generated by the comparison circuit 11 is generated only while the detected current value exceeds the set current value, and is, for example, a periodic pulse capable of counting time.

In the present embodiment, the current value comparison circuit is divided into two according to the processing content to simplify the configuration. That is, the first comparison circuit 11 that generates a signal for counting the time by comparing the detected value of the current value with the set value, and the value obtained by subtracting the set value from the detected value of the current value is positive or negative. In comparison with each other, when positive, that is, when the detected value exceeds the set value, the excess current value is separately provided to the second current value comparison circuit 14 for inputting into the electricity amount calculator 15. .

The electricity amount calculator 15 obtains the excess electricity amount by integrating the values obtained by multiplying the excess current value for each excess time with respect to time, and integrates them.

The electric quantity set in the electric quantity setter 16 is a value determined by the strength of the target supporting ground, and the stop signal to the driving device 6 generated by the electric quantity comparing circuit 17 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, a signal is issued by the first current value comparison circuit 11, the excess time is counted, the excess current value is calculated, and the stirring blade 3 scrapes off a part of the convex portion. Until the time point, another adjoining stirring blade 3 rotates thereafter and comes into contact with the convex portion again, so that the detected current value rapidly increases and the first current value comparison circuit 11 issues a signal.

In the meantime, the stirring shaft 4 descends, the contact and the signal transmission are repeated, and finally the detected current value exceeds the set current value, so that the improved columnar body P to be formed bears the top load. It reaches the position of the supporting ground having a predetermined strength so that it can be effectively transmitted to the supporting ground.

Therefore, by detecting the excess electricity amount obtained from the excess time and the excess current value, which are the count values of the time when the signal is issued, the agitating blade 3 makes temporary contact or continuous contact with the supporting ground. It is possible to manage comprehensively including all the manners of doing so, and it is possible to surely obtain the position of the supporting ground having a constant supporting strength even in the supporting ground which is the foundation on which the improved columnar body P bottoms.

That is, since the power consumption of the rotary drive motor 5 when a load exceeding the capacity of the rotary drive motor 5 at the set current value acts and the excess electricity amount are proportional to each other, the stirring blade 3 is different from the support ground. It is possible to comprehensively determine the position of the supporting ground having a predetermined supporting strength without being affected by the contact in a mode.

When the accumulated excess electricity amount reaches the set electricity amount, the drive device 6 that has lowered the stirring shaft 4 is automatically stopped, and stirring is performed from the improvement material plant through the hose 7, the swivel joint 8 and the stirring shaft 4. While the injection of the improving material pumped to the discharge port at the tip of the shaft is performed, the stirring shaft 4 is pulled up and the improved columnar body P is formed.

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.

In addition, in the support ground position detecting device A of the present embodiment, the integration of the excess electricity amount when the detected current value exceeds the set current value is
A means for limiting 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.
When there is an electric field, the current value of the rotary drive motor 5 rises due to the hard formation S ′, and the electric quantity calculator 15 integrates it as an excess electric quantity caused by contact with a predetermined supporting ground. It is provided to prevent it.

The means for limiting the integration of the excess electricity amount includes a depth detector 18 that detects the depth of the stirring shaft 4, a depth setter 19 that sets the limited depth, and a depth comparison circuit that compares the detected depth and the set depth. 20 and an electromagnetic relay 21 that is activated when the detection depth exceeds a set depth and turns on.The normally open contact 22 of this electromagnetic relay is connected to the first current value comparison circuit 11
And the time counter 12 are interposed.

The depth detector 18 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 setting device 19, for example, a depth at which the influence of the hard stratum S'of the surface layer from the ground surface is eliminated may be set.

By adding such limiting means, after the influence of the hard stratum S'of the surface layer disappears, the time counter 12 starts counting the time and the electricity amount calculator 15 integrates the excess electricity amount. Therefore, the position of the supporting ground H according to the actual ground condition can be detected.

The display means indicated by 23 in FIG. 2 is, for example, a warning lamp, a warning buzzer or the like for informing the operator that the stirring shaft 4 has reached the target supporting ground, and the construction record output also indicated by 24 is
For example, the set current value, the set amount of electricity, the depth reaching the target support ground, and the like are recorded for each improved column.

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

(Effects 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 amount of electricity for restricting the predetermined strength targeted as the support ground. By simply setting the values of and, it is possible to reliably, promptly, and automatically detect a supporting ground position having a certain strength.

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 Unit, 10 ... Current value detector, 11, 14 ... Current value comparison circuit, 12 ... Time counter, 13 ... Current value calculator, 15 ... Electric quantity calculator, 16 ... Electric quantity setter, 17 ... Electric quantity 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 exceeds the set value, a signal is transmitted and the excess current value is obtained, and the signal transmission time is integrated. An excess electricity amount is obtained from the obtained excess time and the excess current value, and the drive device is stopped when the accumulated excess electricity amount obtained by integrating the excess electricity amount is larger than a preset set electricity amount. Ground improvement method. 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. , A current value detector for detecting the current value of the rotary drive motor during rotary drive, and a current that gives a signal when the detected value exceeds the set value by comparing the set value of the current value with the detected value. A value comparison circuit, time counting means for receiving a signal from the comparison circuit and counting the signal generation time to obtain the excess time, and similarly, when the signal is generated in the comparison circuit, the set value is subtracted from the detected value to determine the excess current. A current value calculator for obtaining a value, and an electric quantity operation for calculating an excess electricity quantity from the excess current value obtained by this current value calculator and the excess time obtained by the time counting means and integrating the excess electricity quantity. And a quantity of electricity setting device for setting the value of the quantity of electricity corresponding to the target ground strength in the ground, and the accumulated excess quantity of electricity in the quantity of electricity calculator and the quantity of electricity set in the quantity of electricity setter. The ground improvement machine according to claim 1, further comprising: an electricity quantity comparison circuit that issues a stop signal to the drive device when the accumulated excess electricity quantity is larger than the set electricity quantity.