JPS63297622A - Ground improving work - Google Patents

Abstract

PURPOSE:To raise the efficiency of operation as well as sure operating power by using a controller capable of automatically setting operation elements for a ground improving work in which a powdery improving agent is jetted by compressive air to the ground to form an improved column. CONSTITUTION:A powdery improving agent is jetted by compressed air into the ground to form an improved column by an apparatus having a controller with an arithmetic means 9. A given initial value is set up in an initial value setter 10 and put in the arithmetic means 9. An improving depth Z detected by an improving depth sensor 6 and an air pressure P detected by an air pressure sensor 7 are put through a comparator 8 in the means 9. An air flow rate Q1, improving agent transport amount W1, and penetration speed V1 which are calculated in the means 9 are set up in setters 11, 12, and 13 and automatically controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a ground improvement method in which a powdery improvement material is discharged into the target ground using compressed air to form an improved column.

(Prior Art) Conventionally, as a ground improvement method, a method is known in which a powdery improving material such as cement is discharged into the ground using air pressure, thereby creating improved columns. The required air pressure P in this case is generally P= a −l + b−Qo
2 , , , , , , It is represented by (a). Here, a is the pressure gradient determined by the properties of the ground as shown in Figure 5, Z is the improvement depth, Qo is the air flow rate, [b-
Q021 indicates the pressure loss inside the piping.

For example, for soil improvement up to a depth of 30 TrL, a compression tree with a maximum air pressure cuff of Kgf/ad is generally used. In this ground improvement, the air flow ff1QO in the above equation (A) is set as large as possible in order to increase the discharge efficiency of the improvement material. However, depending on the characteristics of the target ground, the air pressure of the above compressor may exceed the improvement depth of 30 m.
There may be a shortage nearby. In this case, a method is usually adopted in which the air flow ff1QO is adjusted according to the operator's judgment so that ground improvement can be carried out to a depth of up to 30 m within the range of the capacity of the J-NBR.

That is, as shown in FIG. 5, the operator first sets the initial air flow ff1Qo and discharges the improved material while monitoring changes in the air pressure value from the initial air pressure value Pa. Then, the operator predicts the required air pressure value at the final improvement depth of 30 m while observing the change in the air pressure value. In other words, the air pressure value pd at the intersection of the predicted line shown by the broken line in Fig. 5 and the position of the improvement depth of 30 m is 7 kg, which is the compressor removal capacity.
Determine whether f/cd is exceeded. As a result, if it is determined that the compressor capacity is exceeded, the air flow rate value is changed from Qo to 01 at the improvement depth χ where the air pressure filI P b is close to the maximum compressor capacity of 11fi1gf/cd. reduce As a result, the pressure loss value [b-Q02] decreases by ΔP, and therefore the required air; is reduced by ΔP from the force value bpb.
c, and as a result, even with an improved depth of 30 m]
The improved material can be discharged at an air pressure value pe within the range of 7 Kyf/d.

However, in this conventional correction method, the judgment of whether the air pressure is insufficient and the amount of reduction in air outflow are made based on the operator's experience, so the judgment is not quantitative. There is also a risk that the improving material may become clogged at the discharge port due to insufficient pressure due to the timing of decreasing 1'fl or the decrease in 1'fl.

In addition, in the above correction method, only the air outflow is reduced and the amount of improvement material transported remains the same as the initial setting amount, so the mixing ratio of improvement material in the pipe (improvement material 4 transportation results/air flow field)
increases, and there is a risk that the improved material may not be transported sufficiently.

Furthermore, the operator is required to constantly monitor the air pressure value, which impedes labor savings and requires the operator to be a skilled operator.

(Purpose of the Invention) This invention was made to eliminate such conventional drawbacks, and it is possible to accurately reduce air ia by quantitatively determining whether or not air pressure is insufficient depending on the target ground. By doing so, it is possible to prevent unexpected blockage of the improvement material due to insufficient air pressure, and to provide a ground improvement method that can save the labor of the operator.

(Structure of the Invention) This invention provides a process for setting an initial air flow rate value Qo and a zero point of improvement depth in a ground improvement method in which an improvement column is formed by discharging a powdery improvement material into the target ground using compressed air. A step of detecting the initial aerodynamic force value PO at , a step of detecting the improved depth Z1 at which the reference air pressure fiP1 is reached, and a step of detecting the improved depth Z1 and the reference air pressure, assuming that the increase in air pressure is proportional to the depth. (fl P 1 and initial air low force value P.

Based on this, the predicted value P2 of the air pressure at the maximum planned improvement depth Zff1aX is calculated, and the step of calculating the insufficient air pressure value ΔP by subtracting the maximum 51-pair air pressure value Pmax from this prediction (!P2). Air pressure value ΔP
is positive, the reduction rate K is determined by -(Po-ΔP)/Pa based on the insufficient air pressure value ΔP and the initial air pressure value Po, and this is added to the initial air flow value Q0. The modified airflow 1 value Q1 is obtained by multiplying by the reduction rate K, and from the improvement depth 71 to the maximum planned improvement depth Z max, the improved material is discharged at the 1i1 - air flow rate value Q1. This is what I did.

According to the above configuration, based on data on the upper back of air pressure according to the target ground as the improvement depth increases, it is possible to quantitatively determine whether or not air pressure shortage occurs before reaching the maximum improvement depth, and its occurrence. It is possible to determine which items are missing, and based on this, the air pressure can be adjusted at the appropriate timing.

(Example) In the basic soil improvement device shown in Fig. 3, stirring vA
A stirring shaft 1 having a diameter of 11 is held by a leader 12 so that no person can handle the target ground, and this stirring shaft 1 and an improvement material supply tank 2 are connected by an improvement material supply pipe 3. The improvement material 21 in the form of powder in the improvement material supply tank 2 is compressed by compressed air from a compressor 4 (pressurized air source) 4 to be forced to the stirring shaft 1 and discharged into the ground.

When performing soil improvement using this soil improvement device, as the stirring shaft 1 is inserted, the required air pressure P as shown in FIG.
is, P=a −Z+b−Qo 2・・・・・・・・・・・・
As shown in (b), the improved depth Z with a pressure gradient of a
increases in proportion to Here, [b-Qo21 corresponds to a pressure loss term in a pipe such as the improvement material supply pipe 3, and is expressed as an initial air pressure value Pa at the zero improvement depth point.

FIG. 1 shows 7 of the control method which is the main part of the embodiment of this invention.
0-f-I)-t is shown. First, initial values are set in step S1. Cover] Nbretusa 4
Maximum air pressure value pmax, 81 major improvement depth ZIl
ax, initial air flow □□□plant Qo, first use improved shrine transportation product Wo
, initial L1 person speed vO, etc. are set, and ground improvement is started using these set values.

At the same time, a reference air pressure value P1, which serves as a reference for starting the control from 17tl, is set in step S2. This reference air pressure value P11 is 70% of the maximum air pressure value of the compressor tree 4.
It is sufficient to select and use a value between 90% and 90%. For example, when the maximum air pressure of the combiner +j4 is 7Kgrlad, the 6-knot flcIi may be used as the reference air pressure value P1.

Then, in step S3, the initial air pressure value PO at the zero point of the improvement depth is detected, and as the ground improvement work progresses, in step S4, the improvement depth Z1 at which the hay air pressure fiiP1 is reached is detected. As a result, the air pressure value at point A and the improved depths at eight points shown in FIG. 4 are detected.

Based on these set values Pmax, zmax, pl and detected values Po, Pl, Zl, as shown in FIG.
5), the maximum improvement depth Z r
The difference (ΔP) between the predicted required air pressure 1fj at aax (air pressure value P2 at point D) and the maximum air pressure value PmaX of the compressor is determined by 51 points in step S5. Therefore, based on the above initial air pressure value Po, 13 quasi-air pressure kfI P 1 and the improved depth Z1 at that time, the pressure gradient a is determined by a = (Pl-Pa)/Zt, and this pressure gradient a Based on P2 = Pa + a - Z + a; tx, the predicted value P2 of the air pressure at the maximum improved depth ZmaX is obtained, and by adding Ll to this P2, the insufficient air pressure value ΔP is obtained from ΔP=P2-Pmax.

Next, the Stellar 7Sa determines whether or not it is necessary to correct the initial set value Qo of the air flow rate, etc., based on this insufficient air pressure value ΔP. However, the above insufficient air pressure value ΔP
If is negative, even if ground improvement is continued with the above initial setting value] Since it is within the capability range of NMBRESSA 4 (below p max in Fig. 4), there is no need to adjust the initial setting value and control is performed. make it stop. Conversely, the above insufficient air pressure value Δ
When P is positive, the above initial setting value QO is set in step S7.
Find the reduction rate for adjusting etc.

However, the insufficient air pressure value ΔP and the initial air pressure 1st shift F'
Based on o, -(Po-ΔP)/P.

Find the reduction rate K.

Then, in step S8, this reduction rate K is set to the initial setting value Qo of the air flow rate, the amount of improved material transported, and the charging speed.

By multiplying Wo and Vo, each ¥i iI
-, If(h), Wl, Vl are determined. These modified values Q1, Wl, ■1 are set in step S9, and the maximum improvement depth of 7-ma is determined based on these modified values Q1, Wl, vl.
Perform ground improvement up to ×.

Therefore, the pressure loss term in the above equation [b-Q
As shown in Figure 4, o2 is ΔP (°) small [b-
012], the required air pressure value P changes from point B to point 0, and as a result, the required air L1 - force P at the maximum improvement depth Z wax shown at point E becomes the same as the maximum capacity p max of the compressor 4. , ground improvement up to the maximum improvement depth ZIllaX can be performed reliably and effectively within the capabilities of the compressor 4. Therefore, it is possible to quantitatively determine whether or not the air rE force generated by the compressor 4 is insufficient, and to make corrections at the appropriate timing, thereby reducing the risk of blockage of the improved material due to insufficient air pressure. Is it possible to prevent this?

As described above, by reducing the improvement material transport filWo in response to the reduction of the airflow ff1Qo, the improvement material mixing ratio (improvement material transportation amount/air flow) in the improvement material supply pipe 3 is also reduced. Since it is kept constant, the improvement material 21 can also be sufficiently supplied. In addition, by similarly reducing the noble speed VO in response to the decrease in the supply MWo of the improving material 21, the improving material mixture m per medium volume of the improved column 5 is also kept constant, and as a result, the quality is improved. A good improved columnar body 5 can be formed.

Note that in steps S8 and S9, the air flow E
6 and the three first I'll settings of improved material transportation and noble speed 11iQo, Wo, Vo wo'li correct, so (7
) 3) We are trying to improve the ground using the positive value of t'f, but if we at least modify the initial setting value QO of the air flow rate, it will be possible to improve the soil within the range of the maximum air rE force of the compressor 4.
The purpose of making it possible to perform ground improvement to a depth of λ can be achieved.

FIG. 2 shows a control device for carrying out the method shown in FIG. In Fig. 2, a3, the improved depth detection units 6 detect the noble V of the stirring shaft 1 as the improved depth 7, and the air pressure detector 7 detects the force of the air in the pipe from the compressor 4. It is configured. The zero point fli of the improved depth Z and the reference air pressure value P1 are set in advance in the comparator 8, and the detected value (initial air pressure value) at the air It force detector 7 at the set value of this improved depth (Z=O) Po ) and improved depth detection at the air pressure set value P1! The detected value Z1 at step 6 and the set value P1 are input to the performance means 9. As a result, step S2 in FIG.
The work corresponding to step 83 (+5 and step S4) is performed.

On the other hand, the maximum air pressure value plaX of the compressor, the maximum improved deep polishing Zlax, the initial air flow value QO1, the initial improved material transport fitWo, the first II penetration speed Vo, etc. are input to the operation stage 9 by the initial value setting device 10. This allows the first
The work corresponding to step S1 in the figure is performed.

The F recording i means 9 performs operations corresponding to steps S5 to S8 in FIG. It is configured to be As a result, the air flow rate, improvement material transportation amount, and charging speed were determined.

Vl is output as a signal to each setting 1a11, 12.13.

Based on the correction value Q1 of the air flow M, the compressor 4 shown in FIG.
I tltl and control of the charging speed of the stirring shaft 1 based on the correction value V1 of the mold filling speed are each automatically performed and operated.

Note that, as in the above embodiment, it may be configured such that the operation is automatically controlled based on the correction values Q1, Wl, and Vl;
For example, the correction values Q+, W+, and Vl may be displayed in the A operator cabin so that the operator can adjust them by manual movement.

(Effect of the invention) According to the ground improvement method of the present invention, it is determined whether or not the required air pressure is insufficient by comparing it with the maximum air pressure of the pressurized air source being used, and the shortage Eit is determined according to the target ground. before reaching the maximum improvement depth! This makes it possible to accurately adjust the air flow rate, which prevents accidental clogging of the improved material due to insufficient air pressure, and reduces the burden on the operator, resulting in labor-saving fishing results. can do.

[Brief explanation of drawings]

FIG. 1 shows the flow rate of the main part of the embodiment of this invention.
, FIG. 2 is a block configuration diagram without showing the control device that implements the process of the norochart in FIG. 1, and FIG.
Fig. 4 is a diagram showing the relationship between improvement depth and air pressure when soil is improved according to the flowchart in Fig. 1, and Fig. 5 is a diagram of the conventional method. FIG. 3 is a diagram showing the relationship between improvement depth and air pressure when improving the ground according to the above. 4... Compressor (pressure air source), 5... Improved column, 21... Improved material. Patent applicant: Representative of Kobe Steel, Ltd. Patent attorney: Etsushi Kotani
Patent Attorney Long 1) Front Patent Attorney Yasuo Itaya No. 1 Figure 0 Mosui Chiang, -N100

Claims (1)

[Claims] 1. In a ground improvement method in which a granular improvement material is discharged into the target ground using compressed air to form an improved column, a step of setting an initial air flow rate value Q_0 and a step at the zero point of the improvement depth. A step of detecting an initial air pressure value P_0, a step of detecting an improved depth Z_1 that reaches the reference air pressure value P_1, and a step of detecting the improved depth Z_1 and the reference air pressure value, assuming that the increase in air pressure is proportional to the depth. A step of determining a predicted value P_2 of air pressure at the maximum planned improvement depth Zmax based on P_1 and the initial air pressure value P_0, and calculating a deficit air pressure value ΔP by subtracting the maximum planned air pressure value Pmax from this predicted value P_2. and this insufficient air pressure value ΔP
is positive, the reduction rate K is calculated based on the insufficient air pressure value ΔP and the initial air pressure value P_0 by K=√[(P_0-ΔP)/P_0], and the above-mentioned initial air flow rate value Q
_0 is multiplied by this reduction rate K to obtain a corrected air flow rate value Q_1, and the improved material is discharged based on the corrected air flow rate value Q_1 from the improvement depth Z_1 to the maximum planned improvement depth Zmax. A ground improvement method that is characterized by: