JPH0568571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for a ground improvement machine.

(Prior art) Ground improvement machines that employ the powder injection mixing method (DJM) have been known for a long time. Normally, the amount of fuel injected is kept constant. In this construction method, if the soft ground to be improved has uniform soil quality in the depth direction, the improvement material and ground soil are stirred and mixed almost uniformly, making it possible to create improved pillars with uniform strength. However, if the geology is not uniform because different strata overlap in the depth direction, the improvement material and ground soil should be uniformly mixed by stirring and keeping the discharge amount of the improvement material and the penetration and withdrawal speed constant. However, there was a problem that it was not possible to create improved columns with uniform strength.

(Purpose of the Invention) The present invention has been made in order to solve such problems, and it is possible to create improved columns with uniform strength even in soft ground where different strata overlap. The present invention provides a control device for an improved machine.

(Structure of the Invention) The present invention includes: a means for rotationally driving a stirring shaft having a stirring blade at the lower end; a means for penetrating and withdrawing the stirring shaft; and an improved material discharging means for discharging the improved material from the tip of the stirring shaft. In the soil improvement machine, a stirring torque detection means of a stirring shaft, a stirring shaft penetration/pulling resistance detection means, a stirring shaft penetration/pulling speed detection means, a stirring shaft rotational speed detection means, and a stirring blade rotation radius storage means. Then, the amount of work per unit volume is calculated based on the signals of the stirring torque of the stirring shaft, the penetration and withdrawal resistance, the penetration and withdrawal speed, the rotational speed, and the rotation radius of the stirring blade, which are input from each of the detection means and the storage means. a calculating means, a means for setting a target amount of work per unit volume, a means for comparing and determining the amount of work per unit volume inputted from the calculating means and the setting means and the target amount of work per unit volume, and the above-mentioned comparison. control means for sending a penetration/extraction speed control signal to the penetration/extraction means so as to reduce the deviation between the amount of work per unit volume and the target amount of work per unit volume based on the signal from the determination means; It is characterized by the presence of

With the above configuration, the work amount per unit volume calculated based on the stirring torque of the stirring shaft, penetration and withdrawal resistance, penetration and withdrawal speed, rotational speed, and rotation radius of the stirring blade is used as a judgment criterion, and the reality and work amount are The penetration and withdrawal speed of the stirring shaft is controlled according to the deviation from the target amount of work determined in advance through geological boring surveys, mixing of improved materials indoors, reaction tests, etc., and the amount of work is adjusted according to the geology. Optimal ground improvement is performed in this process, resulting in improved columns with uniform strength.

(Example) The schematic configuration of a soil improvement machine will be explained with reference to FIG. A stirring shaft 3 is supported by a leader 2 erected on a base machine 1 so as to be rotatable and movable up and down. The stirring shaft 3 is hollow and has a reforming material feeding passage therein, and its outer shape is square in cross section, and its lower end is provided with radial stirring blades 4 and an improving material discharge port (not shown).

The rotational drive means 5 for the stirring shaft 3 has a shaft rotation driving electric motor 5a and a reducer 5b, and the stirring shaft 3 is inserted into the reducer 5b so as to be slidable only in the axial direction. It transmits rotational torque while allowing sliding in the axial direction, that is, lifting and lowering.

The penetration/extraction means 6 for the stirring shaft 3 has a penetration winch 6a and a withdrawal winch 6b, and the tip of a penetration rope 6c wound around the penetration winch 6a is connected to the upper end of the stirring shaft 3. Thrust bearing 3a
A pulling rope 6d wound around the pulling winch 6b is connected to the upper part of the thrust bearing 3a. Both winches 6a, 6 mentioned above
b are each driven by a hydraulic unit 6e equipped with a hydraulic motor, a variable displacement hydraulic pump, etc.
Due to the drive, the stirring shaft is raised and lowered, and
Penetration and extraction are performed on the

The improvement material discharging means 7 is equipped with a feed wheel 7c driven by a variable speed electric motor 7b at the lower part of the tank 7a, and the compressed air introduced from the pipe 7d and the rotation of the feed wheel 7c are connected to each other. Improved material B stored in tank 7a by
is pneumatically fed to the improvement material supply hose 7e. The tip of the hose 7e is connected to the upper end of the stirring shaft 3 via a swivel joint (not shown).
The improved material pneumatically fed to e is fed into the stirring shaft 3 and is discharged from the leaf outlet provided at the tip of the stirring shaft 3.

Next, a method of improving the ground using the above ground improving machine will be explained. While the stirring shaft 3 is rotated by the stirring shaft rotation driving means 5, the drawing rope 6d is fed out by the drawing winch 6b of the penetrating and drawing means 6, and the penetrating rope 6c is wound up by the penetrating winch 6a, thereby stirring. The shaft 3 is lowered to penetrate into the soft ground A, and during this penetration, the ground soil is stirred by the stirring blade 4 at the tip of the stirring shaft. After penetrating the stirring shaft 3 to a predetermined depth,
While rotating the stirring shaft 3, the penetration winch 6a lets out the penetration rope 6c, and
By winding up the pulling rope 6d with the pulling winch 6b, the stirring shaft 3 is raised and pulled out of the soft ground A. At the time of pulling out, the improved material is discharged from the outlet at the tip of the stirring shaft, and the stirring blade 4, soil improvement is performed by stirring and mixing the improvement material and the ground soil. Note that the improving material may be discharged when the stirring shaft 3 penetrates.

Next, a control device for the above ground improvement machine will be explained with reference to FIG. The rotation speed detection means 10 is attached to the speed reducer 5b of the stirring shaft rotation driving means 5, etc.
Detects the rotation speed n (rpm) of the The stirring torque detection means 11 includes a rotation speed detection means 10, a power detection means 11a for detecting the electric power E (kw) of the electric motor 5a of the rotational drive means 5, both detection means 10,
The stirring torque calculation means 11b calculates the stirring torque Tor based on the rotation speed n and the electric power E detected by the rotation speed n detected by the stirring torque calculation means 11a. Stirring torque Tor is Tor
It can be found as =974×E/n (Kgfm).

The penetration/extraction resistance detection means 12 of the stirring shaft 3 includes a hydraulic pressure detection means 12a that detects pump discharge pressure P (Kgfcm 2 ) by a pressure detector provided in the hydraulic unit 6e of the penetration/extraction means 6, and a hydraulic pressure detection means 12a that detects the pump discharge pressure P (Kgfcm ² ). and a penetration/extraction resistance calculating means 12b for calculating the penetration/extraction resistance Res (Kgf) based on the following. Penetration and withdrawal resistance
Res is determined by Res=K ₁ P+K ₂ . however,
K ₁ and K ₂ are constants determined by the capacity and mechanical loss of the hydraulic pump.

The penetration/extraction speed detecting means 13 detects the lifting/lowering speed of the stirring shaft 3, and for example, the penetration/extraction speed detection means 6
The rotation speed of each guide sheave of the penetration rope 6c and the withdrawal rope 6d is detected, and the penetration and withdrawal speed υ (m/min) of the stirring shaft 3 is calculated from the rotation speed. The rotation radius r (m) of the stirring blade 4 is stored in the blade rotation radius storage means 14 .

The rotation speed n of the stirring shaft 3 and the stirring torque detected by each of the above-mentioned detection means 10, 11, 12, 13
Tor, penetration and withdrawal resistance Rse, penetration and withdrawal speed υ, and rotation radius r of the stirring blade 4 stored in the storage means 14.
is input to the calculation means 15, and this calculation means 15
The amount of work W/V per unit volume is calculated.

Now, as shown in Figure 3, the stirring blade 4 rotates once,
Consider the improved column C when the ground is improved by penetrating (and pulling out) by a length l in the axial direction. The reaction force of the rotation of stirring blade 4 is F, and the penetration resistance is Res
Then, the amount of work W ₁ due to rotation and the amount of work W ₂ due to penetration are as follows.

W ₁ = F・2πr, W ₂ = Res・l On the other hand, since the volume V of the improved column is πr ² l, the amount of work per unit volume W/V (tf・m/m ² )
is expressed by the following equation.

W/V=(F·2πr+Res·l)/πr ² l... Here, the stirring torque Tor is expressed as Tor=F·r. Further, if the time for the stirring blade 4 to move in the axial direction by a length l is set as t (sec), the length l is
= υ・t/60, time t is t=60/n (however,
υ: penetration and withdrawal speed, n: rotational speed).

Therefore, the amount of work per unit volume in the above formula W/
V can be replaced as follows.

W/V={Tor・2π+Res(υ/n)} /πr ² (υ/n) =2n・Tor/r ² υ+Res/πr ² ... The amount of work W per unit volume calculated by the calculating means 15 in this way /V is the following comparison and determination means 16
is input. On the other hand, the target amount of work s per unit volume (where s is the ideal value of the amount of work W/V per unit volume) is calculated in advance through geological boring surveys, mixing of improving materials indoors, reaction tests, etc. , the target amount of work s is set in the target amount of work setting means 17, and the target amount of work s is input from this setting means 17 to the comparison and determination means 16.

Next, the comparison and determination means 16 compares and determines the current amount of work per unit volume W/V calculated by the calculation means 15 and the target amount of work s, and based on the determination result, the following is determined. Control takes place.

That is, in the penetration and withdrawal speed control means 18, the penetration and withdrawal speed υ ₀ for achieving the target work amount s is set in advance in the penetration and withdrawal speed setting means 18a, and the setting point υ ₀ and the above comparison determination means are set in advance. Based on the results of the comparison and determination by 16, the required penetration and withdrawal speed υi is calculated by the penetration and withdrawal speed calculation means 18b. Next, the required oil amount q=K ₃ υ of the penetration/extraction means 6 is calculated by the oil amount calculation means 18c based on the penetration/extraction speed υi. however,
K ₃ is a constant determined by the machine. Thereafter, a signal corresponding to the oil amount q is sent from the signal generating means 18c to the flow rate controller of the penetration/extraction means 6, thereby controlling the discharge amount of the hydraulic pump and controlling the penetration winch 6a and the extraction winch 6b. The rotation speed is controlled, and the penetration speed or withdrawal speed of the stirring shaft 3n is controlled.

On the other hand, in the improvement material discharge amount control means 19, the improvement material discharge amount Q0 for achieving the target work amount s is set in advance in the improvement material discharge amount setting means _19a , and the set value _Q0 and the above-mentioned Comparative determination means 1
Based on the results of comparison and discrimination in step 6, the required improvement material discharge amount is determined by the improvement material discharge amount calculation means 19c.
Qi is calculated. Next, the rotation speed ni of the feed wheel 7c of the improved material discharging means 7 is calculated based on the discharge amount Qi, and a signal corresponding to this rotation speed _n1 is sent from the signal generating means 19d to the improved material discharging means 7.
The rotational speed of the motor 7b, that is, the rotational speed of the feed wheel 7c, is controlled.
The amount of improvement material fed into the soft ground is controlled, and the amount of improvement material discharged from the tip of the stirring shaft 3 into the soft ground is controlled.

The above control will be explained in more detail as follows.

Based on the result of the discrimination between the work volume W/V and the target work volume s by the comparison and discrimination means 16, for example, the amount of change in the work volume W/V is set as a control standard of ±20%, and the penetration and withdrawal speed calculation means 18b and the improvement are performed. The material discharge amount calculation means 19b calculates the penetration and withdrawal speed υi and the improved material discharge amount Qi as follows.

When W/V>s, determine whether W/V>1.2s or not, and when W/V>1.2s, υi=1.2υ ₀ , Qi={2.2−(W/V)/s} Let Q be ₀ .

When W/V≦1.2s, υi={(W/V)/s}υ ₀ and Qi=Q ₀ .

When W/V≦s, determine whether W/V<0.8s, and when W/V<0.8s, υi=0.8υ ₀ , Qi={1.8−(W/V)/s} Let Q be ₀ .

When W/V≧0.8s, υi={(W/V)/s}υ ₀ and Qi=Q ₀ .

Hereinafter, the required oil amount q is calculated based on the penetration and withdrawal speed υi obtained by the above calculation, and the penetration and withdrawal speed υ of the stirring shaft 6 by the penetration and withdrawal means 6 is controlled, and at the same time, it is determined based on the improvement material discharge amount Qi. Then, the rotation speed ni of the feed wheel 7d of the improvement material discharging means 5 is determined, and the rotation speed of the electric motor 7b is controlled to control the amount of improvement material discharged.

By the above control, an improved column with uniform strength can be obtained. In other words, when different strata overlap and the geology is not uniform, the penetration and withdrawal resistance of the stirring shaft 3 changes, and the amount of work W/V per unit volume changes, so this amount of work W/V is not constant. By controlling the soil so that it is the same, work corresponding to the geology, that is, ground improvement, is performed, and as a result, improved columns with uniform strength can be obtained.

Incidentally, in the above embodiment, the penetration and withdrawal speed and the discharge amount of improving material were controlled, but it is also possible to arbitrarily control the rotation speed of the stirring shaft 4 by the penetration and withdrawal means 6 using the same control as above. . Furthermore, in the present invention, it is not necessarily necessary to control the discharge amount of the improving material, and it is possible to obtain an improved column body that is sufficiently superior to the conventional one just by controlling the penetration and withdrawal speed.

In the above ground improvement machine, the means 6 for penetrating and extracting the stirring shaft 3 is not limited to the winch type shown in FIG.
The stirring shaft may be inserted or withdrawn at regular intervals using a chuck mechanism and a hydraulic cylinder for insertion and withdrawal. In this case, the supply flow rate to the hydraulic cylinder may be controlled to control the expansion and contraction speed of the cylinder, and the penetration and withdrawal speed of the stirring shaft may be controlled.

The control device of the present invention is applicable not only to ground improvement machines for land use but also to ground improvement machines for submarine use.

(Effects of the Invention) As described above, the present invention controls the penetration and withdrawal speed of the stirring shaft in accordance with the amount of work per unit volume required for stirring during soil improvement work so that the amount of work is constant. Through this control, even if different geological strata overlap and the geology is not uniform, ground improvement can be performed according to the geology, and an improved column with uniform strength can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a schematic side view showing an example of a ground improvement machine equipped with the control device of the present invention, and Fig. 3 is a diagram for calculating the amount of work per unit volume. FIG. 3... Stirring shaft, 4... Stirring blade, 5... Stirring shaft rotation drive means, 6... Stirring shaft penetration/extraction means, 7...
Improvement material discharging means, 10... Stirring shaft rotation speed detection means, 11... Stirring torque detection means, 12... Penetration and withdrawal resistance detection means, 13... Penetration and withdrawal speed detection means, 14... Stirring blade rotation radius storage means , 15...
Work amount calculation means per unit volume, 16... Comparison/discrimination means, 17... Target work amount setting means, 18...
Penetration and withdrawal speed control means.

Claims (1)

[Claims] 1. In a soil improvement machine equipped with a stirring shaft rotation drive means having a stirring blade at the lower end, a stirring shaft penetration/extraction means, and an improved material discharging means for discharging the improved material from the tip of the stirring shaft, the stirring shaft is A torque detection means, a stirring shaft penetration and withdrawal resistance detection means, a stirring shaft penetration and withdrawal speed detection means, a stirring shaft rotational speed detection means, a stirring blade rotation radius storage means, and each of the above-mentioned detection means and storage means. Stirring torque of the stirring shaft input from, penetration and withdrawal resistance, penetration and withdrawal speed, rotation speed,
a calculation means for calculating the amount of work per unit volume based on each signal of the rotation radius of the stirring blade; a means for setting the target amount of work per unit volume; means for comparing and determining the amount of work and the target amount of work per unit volume; and a means for reducing the deviation between the amount of work per unit volume and the target amount of work per unit volume based on the signal from the comparison and determining means. and control means for sending a penetration/extraction speed control signal to the penetration/extraction means.