JPS6340886B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a grout concentration adjustment method that can adjust the concentration of grout injected into the ground to a desired concentration in ground improvement work that occurs in conjunction with dam construction work, etc. and a concentration adjustment device.

Grouts mainly used in dam construction work include:
There are cement suspensions, which are made by mixing cement in water, and cement-bentonite suspensions, which are made by mixing cement and bentonite in water. To prevent clogging, it is recommended to first inject grout with a lower concentration and gradually switch to grout with a higher concentration. The above grout composition is usually expressed as the weight ratio of water and substances other than water, such as water and cement, and if the weights of water, cement, and bentonite contained in the grout are W, C, and B, respectively, The concentration of cement suspension is expressed as W/C, and the concentration of cement bentonite suspension is expressed as W/C+B, and generally this value is
Grouting is carried out in the range of 10-1.

Grout can be manufactured either by weighing each ingredient and mixing and stirring to achieve a predetermined concentration, or by preparing grout with the highest concentration in advance and using this as a stock solution by adding water to the stock solution. There are cases where the grout is made into a concentrated grout, but in either case, the stirring capacity of the mixer normally used is 200, so
Most grout is manufactured in units of 200, and the grout concentration switching standard based on the prescribed injection amount stated in the construction specifications is such that each concentration is a multiple of 200.

Broadly speaking, the grout concentration switching standards are as follows: 1 Switching according to specified time.

2 Switching based on the specified injection amount.

3 Switching by injection amount per hour.

However, based on the standard principle of injecting more cement or cement and bentonite in a shorter time and past construction results, the above 1, 2,
In most cases, three types of switching are used together, and independent switching is rarely performed.

For this reason, if the concentration has to be changed even though there is a remaining amount in the mixer, the remaining amount must be discarded. It has also been reported that 19% was waste.

As mentioned above, in conventional grouting work, a large amount of the manufactured grout is discarded, which is not only extremely uneconomical, but also has many problems such as the cost of disposing of the discarded grout.

In addition, Japanese Patent Application Laid-open No. 53-61111 describes a technology for a composite grouting method in which grout materials stored in multiple containers are transported through injection pumps, flow meters, and control valves, and then merged and injected into the ground. However, the above technique not only requires multiple injection pumps for each container, which increases the cost of the equipment, but also requires multiple grout materials to be injected into the ground by simply merging them without mixing them. Apart from reactive grout materials that do not contain particles such as cement and are extremely easy to mix, they are unsuitable for injecting grouts that contain particles such as cement or even bentonite.

The purpose of this invention is to provide a grout concentration adjustment method and a grout concentration adjustment device that solve the above-mentioned problems. is temporarily stored in a storage tank, and the grout stock solution is conveyed in this order to a check valve, a mixer, and a grout pump, and is further diluted to a predetermined concentration with water supplied from between the check valve and mixer via a flow rate adjustment valve. The grout concentration adjustment device is characterized in that a grout pump is connected via a suction pipe to a storage tank that temporarily stores grout stock solution made in a mixing plant, etc. It is characterized in that a stop valve and a mixer are provided, a branch port is provided between the check valve and the mixer, and the branch port is connected to a water supply port via a flow rate regulating valve.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings, taking grout injection in dam construction as an example.

Figure 1 shows an example of a grouting system diagram, in which 1 is a storage tank equipped with an agitator 2, 3 is a suction pipe connected to the storage tank 1, and 4 is installed in the middle of the suction pipe 3. A check valve, 5 is a grout pump installed ahead of the check valve 4 in the suction pipe 3, 6 is a line mixer installed between the check valve in the suction pipe 3 and the grout pump 5, 7 is a reverse A flow rate adjustment valve provided on a water supply pipe 8 branched from between the stop valve 4 and the line mixer 6, and 9 a water flow rate detection provided between the flow rate adjustment valve 7 of the water supply pipe 8 and the water supply port 10. 11 is an injection pipe connected to the tip of the grout pump 5, 12
13 is a grout flow rate detector provided in the middle of the injection pipe 11, and 13 is a grout flow rate detector 1 of the injection pipe 11.
A grout pressure detector is attached to a branch beyond 2, 14 is an injection port, 15 is the ground, and 16 is a grout stock solution.

A grout stock solution 16 is prepared using a mixer not shown in FIG.
When the grout stock solution 16 in the storage tank 1 is activated,
reaches the check valve 4 through the suction pipe 3. On the other hand, the pressure water supplied from the water supply port 10 is sent to the flow rate adjustment valve 7 via the water supply pipe 8 and the water flow rate detector 9, and the amount of water is adjusted so that the grout has a predetermined concentration. The grout that flows in through the valve 4 is combined with the grout stock solution, mixed by the line mixer 6, and sucked into the grout pump 5. The grout discharged from the grout pump 5 passes through the injection pipe 11 and the grout flow rate detector 12 to the injection port. 14 into the ground 15.

Note that once the concentration of the grout stock solution is constant and the concentration of grout to be injected is determined, the supply of water is inevitably determined based on the value measured by the grout flow rate detector 12, so the flow rate of the water is automatically determined. Adjust and supply.

Figure 2 shows, as a reference, an injection system diagram for injecting grout at a predetermined concentration without diluting it with water. The sucked grout 16' is pressurized here and discharged into the injection pipe 11, passes through the grout flow rate detector 12, and enters the injection port 14.
It is injected into the ground 15. In addition, the injection pipe 11 includes
A return pipe 17 is provided from before the grout flow rate detector 12 via an automatic return valve 18, and the return pipe 17 is set according to the detection signals from the grout flow rate detector 12 and the grout pressure detector 13 and injection conditions. Flow pressure control device 19 based on the value
actuates the automatic return valve 18 to return excess grout 16' to the storage tank via the return pipe 17;
It is designed to maintain a predetermined flow rate and pressure.

In the above reference example, although it is possible to control the flow rate and pressure, it is not possible to inject grout with different concentrations as necessary. Therefore, a fixed displacement grout pump is used, and an automatic return valve is used to control the injection pressure and grout flow rate.
There is also a need for a method and apparatus that can perform grout injection while adjusting the concentration.

Figure 3 is a grouting system diagram 1 that meets the above requirements.
For example, 1 is a storage tank equipped with an agitator 2, 3 is a suction pipe connected to the storage tank 1, 4 is a check valve installed in the middle of the suction pipe 3, and 5' is a suction pipe. 3
6 is a line mixer installed between the check valve 4 of the suction pipe 3 and the constant displacement grout pump 5', and 7 is a check valve. A flow rate adjustment valve 9 is provided in the water supply pipe 8 branched from between the valve 4 and the line mixer 6, and 9 is the flow rate adjustment valve 7 of the water supply pipe 8 and the water supply port 1.
11 is an injection pipe connected to the end of the grout pump 5', 12 is a grout flow rate detector provided in the middle of the injection pipe 11, and 13 is a grout in the injection pipe 11. Flow rate detector 12
A grout pressure detector is installed by branching further forward, 14 is the injection port, 15 is the ground, 16 is the grout stock solution, and 17 is a grout pressure detector branched from the injection pipe 11 before the grout flow rate detector 12 and installed in the line mixer 6. Return pipe connected to storage tank 1 side, 18 is return pipe 17
19 is a flow rate pressure that controls and drives the automatic return valve 18 based on detection signals from the grout flow rate detector 12 and grout pressure detector 13 and set values determined by injection conditions. It is a control device.

A grout stock solution 16 is prepared by a mixer not shown in FIG. 16 reaches the check valve 4 via the suction pipe 3.
On the other hand, the pressure water supplied from the water supply port 10 is sent to the flow rate adjustment valve 7 via the water supply pipe 8 and the water flow rate detector 9, and the amount of water is adjusted so that the grout has a predetermined concentration. The grout that flows in through the valve 4 is combined with the grout stock solution, mixed by the line mixer 6, and sucked into the fixed displacement grout pump 5'.The grout that is discharged passes through the injection pipe 11 and reaches the automatic return valve 18, and the grout is The automatic return valve 1 is operated so that the flow rate and pressure are set in advance by the flow rate pressure control device 19 based on the values measured by the flow rate detector 12 and the grout pressure detector 13.
8, the excess grout is returned to the line mixer 6 via the return pipe 17, and an appropriate amount of grout is sent to the ground 1 via the grout flow rate detector 12 and the injection port 14.
Injected into 5.

In the above embodiment, the flow rate of excess grout is independent of the water flow rate detector 9 and the grout flow rate detector 12, and there is no difference in concentration adjustment when using a variable displacement grout pump as shown in FIG.
Either a variable displacement grout pump or a fixed displacement grout pump can be used, and the grout flow rate and pressure can be controlled.

In the embodiment described in FIGS. 1 and 3,
It is convenient to set the concentration of the grout stock solution to the highest concentration of the grout used, and if the suction pipes of multiple grout pumps are connected to the storage tank 1, grout can be poured from multiple injection ports. Can be injected into the ground. It goes without saying that other mixers may be used in place of the line mixer.

The method and apparatus for adjusting the grout concentration using the flow rate adjustment valve 7 have been described above, but the method for automatically controlling the flow rate adjustment valve will be described below.

FIG. 4 shows the grout pump 5 in FIG.
FIG. 5 shows the relationship between the suction flow rate and the discharge flow rate of the constant displacement grout pump 5' in FIG.
is the water flow rate, 22 is the grout flow rate, and 23 is the return grout flow rate. Here, the grout stock solution concentration, cement specific gravity, bentonite specific gravity, and ratio of bentonite to cement are known, and the water flow rate is 2.
If the ratio between 1 and the grout stock solution flow rate 20 is known, the grout concentration can be determined. However, the value of the water flow rate 21 is determined by the water flow rate detector 9, and the value of the grout flow rate 22 is determined by the water flow rate detector 9.
Since the value of is determined by the grout flow rate detector 12, the grout concentration at that time can be determined by calculation, and the flow rate regulating valve 7 may be controlled so that the value approaches the required concentration, that is, the set concentration. Such a grout concentration control device can be made compact and inexpensive with high performance by using a microcomputer.

FIG. 6 shows an example of a circuit system diagram of the above-mentioned grout concentration control device, in which 24 is a constant setting circuit;
5 is an arithmetic circuit, 26 is a comparison circuit, 27 is a concentration setting circuit, and 28 is a flow rate adjustment valve drive circuit. Here, the concentration of the grout stock solution K _O , the cement specific gravity d _C , the bentonite specific gravity d _B , and the ratio α of bentonite to cement are set in the constant setting circuit 24.
The concentration of grout to be injected is set in the concentration setting circuit 27. Grout stock solution concentration K _O , cement specific gravity d _C , bentonite specific gravity d _B , ratio of bentonite to cement α set in constant setting circuit 24, water flow rate value q _W obtained by water flow rate detector 9, and The value q of the grout flow rate obtained by the grout flow rate detector 12 is input to the arithmetic circuit 25, and the concentration of the grout being injected is determined by arithmetic processing, and this value is sent to the comparison circuit 26. circuit 26
Since the grout concentration K to be injected is inputted from the concentration setting circuit 27, the comparison circuit 26 compares the calculated grout concentration and the preset grout concentration K to be injected, and determines that the values are equal. An instruction to operate the flow rate adjustment valve 7 is sent to the flow rate adjustment valve drive circuit 28, and the grout concentration is determined by driving the flow rate adjustment valve 7 and adjusting the opening degree of the valve. Adjust to the desired grout concentration.

Note that the comparison circuit 26 automatically receives instructions for injection concentration based on the grout concentration switching conditions, grout flow rate, and pressure information specified by construction specifications, etc., rather than the grout concentration input from the concentration setting circuit 27. A concentration instruction from a grout concentration switching indicating device (not shown) may be input, and in this case, the operator may input the concentration instruction from the concentration setting circuit 2 each time.
It is possible to automatically perform injection that satisfies the given grout concentration switching conditions without setting the concentration to 7.

In this invention, the water supply pipe 8 is provided with a flow rate adjustment valve, and the suction pipe 3 is also provided with a flow rate adjustment valve, and the two flow rate adjustment valves may be controlled to adjust the grout concentration. A three-way valve is installed at the branch port where the grout solution and water side ports meet, and the grout concentration is adjusted by adjusting the three-way valve. Good too.

This invention is constructed as described in detail, and if an attempt is made to open the flow rate adjustment valve and pressurize water in an amount greater than the suction capacity of the grout pump, the check valve will not open and only water will be discharged from the grout pump. This not only makes it possible to carry out water pushing or water permeability tests that are carried out prior to grout injection, but also allows the grout concentration to be adjusted at any time, eliminating the need for discarding the grout that has gone to great lengths as in the past. This method has many effects, such as better and more efficient grout injection, less expensive equipment since only one grout pump is required, and a large reduction in labor and materials.

[Brief explanation of drawings]

Attached drawings Figures 1 to 3 are diagrams showing three examples of grout injection system diagrams, Figures 4 and 5 are diagrams showing the relationship between the suction amount and discharge amount of a grout pump, and Figure 6 is an example of a control circuit. FIG. 1... Storage tank, 2... Stirrer, 3... Suction pipe,
4... Check valve, 5, 5'... Grout pump, 6
... Line mixer, 7 ... Flow rate adjustment valve, 8 ...
Water supply pipe, 9... Water flow rate detector, 10... Water supply port, 11... Injection pipe, 12... Grout flow rate detector, 13... Grout pressure detector, 14... Inlet, 15... Ground, 16... Grout stock solution, 17
... Return pipe, 18 ... Automatic return valve, 19
...Flow rate pressure control device, 20... Grout stock solution flow rate, 21... Water flow rate, 22... Grout flow rate, 2
3...Return grout flow rate, 24...Constant setting circuit, 25...Arithmetic circuit, 26...Comparison circuit, 27
... Concentration setting circuit, 28 ... Flow rate adjustment valve drive circuit.

Claims (1)

[Scope of Claims] 1. A grout stock solution made in a mixing plant or the like is temporarily stored in a storage tank, and the grout stock solution in the storage tank is transported in this order to a check valve, a mixer, and a grout pump, and the above-mentioned check valve A grout concentration adjustment method characterized by diluting the grout to a predetermined concentration with water supplied from between the mixer and the mixer via a flow rate adjustment valve and conveying the diluted grout. 2. A grout pump is connected via a suction pipe to a storage tank that temporarily stores grout stock solution made in a mixing plant, etc., and a check valve and a mixer are installed in the middle of the suction pipe, and a check valve and a mixer are installed in the middle of the suction pipe. A grout concentration adjusting device, characterized in that a branch port is provided in between, and the branch port is connected to a water supply port via a flow rate regulating valve.