JPH04115905A - Density measuring method and casting controlling system of grout material - Google Patents

Abstract

PURPOSE:To measure grout density at a low cost and with high precision, by a method wherein a grout material is sent under a state where both pipe bodies are vibrated slightly by anti-phase resonant frequency through an excitation coil and a phase difference between those at entrance side and exit side of both the pipe bodies to be generated by feed of the grout material is detected by an optical sensor. CONSTITUTION:A grout material to be pressure-fed is entered into a device through an entrance side feed pipe 10, branches to vibration pipe bodies 11a, 11b provided by standing in a row, joined again and fed up to a predetermined casting position. The vibration pipe bodies 11a, 11b are vibrated slightly by anti-phase resonant frequency under a state where the grout material is not fed or stopped by an excitation coil 13 fitted to a protective pipe 14. Since the vibration pipe bodies 11a, 11b vibrating slightly under this anti-phase state do not receive Coriolis force, a fixed vibration state is kept on. However, since the grout material passes through within the vibration pipe bodies 11a, 11b, the vibration pipe bodies receives the Corolis force and a phase difference is generated in vibrations between those at their entrance side and exit side. The phase difference is detected by optical sensors 12a, 12b and a mess flow is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the density of grout and an injection management system for grout.

[Conventional technology]

In dam and tunnel construction, cement milk injection is used to fill gaps in bedrock with cement milk to prevent water leaks and springs, and to strengthen bedrock. Additionally, cement mortar is generally injected to fill cavities created in the foundations of structures due to ground subsidence, or to backfill tunnels and shields.

However, with this type of injection method, it is practically impossible to confirm the injection effect at all injection positions after injection. Therefore, it is necessary to control in advance whether the grout material to be injected has a predetermined density or the like.

Conventionally, as a density detection device for grout materials such as cement milk and mortar, for example, the Japanese Patent Publication No. 57-456
In Publication No. 48, radioisotope (hereinafter referred to as R1
Regarding a gamma ray densitometer using a gamma ray densitometer, a detection system with high counting efficiency is constructed by arranging multiple transmitted gamma ray detection units in the tube body part on the side opposite to the RI for a tube through which cement milk, etc. flows. discloses a density measuring device that significantly reduces leakage gamma rays, increases safety, and is easy to use.

[Problem to be solved by the invention]

However, although the RI type density meter described in Japanese Patent Publication No. 57-45648 is useful in that it can continuously measure the density of grout, the measuring device itself is expensive and uneconomical. It is difficult to ensure accuracy due to the transmission attenuation of the radiation source, and furthermore, in areas with low density, for example, when density ρ≦1.082 (g/c+++'), measurement accuracy is extremely reduced due to background noise. There was a problem.

Conventionally, when controlling the injection of grout using the RI type density meter, it is necessary to use an RI
When a type density meter is incorporated, there are problems such as its handling is special, so it has to rely on a specialist, and its management becomes indirect and complicated. In addition, since the RI density meter emits gamma rays that are harmful to the human body, the Radiation Hazard Prevention Act requires various procedures such as application for approval and notification of use, radiation dose management, and health management. Because of this, there are problems such as cumbersome procedures and management.

Furthermore, since the grout injection material detection control section F is installed by different companies and operators, it has two systems: a control section F for flowmeters and pressure gauges, and a control section F2 for the RI density meter. As a result, there are problems such as production and management being complicated and troublesome.

Therefore, the main object of the present invention is to provide a density meter for grout that is low cost, highly accurate, and easy to handle and manage.

[Means to solve the problem]

The above problem was solved by installing two pipes in parallel and using an excitation coil.
With both tubes being slightly vibrated at resonant frequencies with opposite phases, grout is fed to both tubes, and the phase difference between the inlet and outlet sides of both tubes caused by this grout feeding is corrected. This problem can be solved by measuring the grout density by detecting it with an optical sensor.

[Effect]

Conventionally, in the field of grouting work, the actual situation has been to rely only on adjusting the blending ratio of cement and water or fine aggregate during the mixing stage, and density control has not been achieved during the pumping of grout. Furthermore, even if density control is attempted during grout pumping, the lack of an appropriate method to continuously measure density during the grouting process is one of the reasons why density control during pumping is not carried out as mentioned above. be. However, in recent years, the importance of injection control at the injection stage has been reaffirmed, and the development of a useful density measuring device has been desired.

In recent years, in order to meet this demand, the special public service No. 57-45648
Although the RI type density meter described in the publication is disclosed, there are still many problems as mentioned above.

The present invention has been devised in view of the above problems. The inventors investigated various types of grout density meters that can be used to measure grout density at low cost and with high precision, and are easy to handle and manage. We investigated the possibility of measuring grout density using a Coriolis mass flowmeter that can measure mass flow rate and density.

A mass flowmeter is a measuring device that displays the amount of fluid flowing per unit time in terms of mass, but can also measure density. However, given the current situation in Japan, mass flowmeters have not yet become widely used, and it is not certain whether they can guarantee highly accurate density measurements for grout materials.

Therefore, based on tests in Examples described later, the present inventors confirmed that highly accurate density measurements of grout materials could be performed, and succeeded in putting the method into practical use.

In the Coriolis mass flowmeter, first, two tube bodies are arranged side by side, and both tube bodies are caused to vibrate slightly at resonant frequencies of opposite phases using an excitation coil. Note that in this state, the flow rate is zero or is in a stopped state, so the tube body is not subjected to the Coriolis force and continues to vibrate constantly. When the liquid to be measured is sent to both tubes in this vibrating state, the Coriolis force causes a phase difference between the inlet and outlet sides of the tubes. Since this phase difference is proportional to the mass flow rate, the density is measured by detecting this phase difference with an optical sensor.

As is well-known, the Coriolis force is an apparent force that acts only on a moving object in a rotating coordinate system.If the angular velocity ω of the coordinate system relative to the inertial frame is constant, this force, excluding the centrifugal force, Become. If the unit vector in the rotational axis direction is n, the mass of the object is m, and the speed seen from the rotational coordinate system is ■, then the Coriolis force is expressed as Fc=2mω[nv].

[Specific configuration of the invention]

Hereinafter, the Coriolis mass meter according to the present invention will be explained in detail.

FIG. 4 is a diagram showing a Coriolis mass flowmeter, and FIG. 5 is a diagram showing a grout feed pipe portion of the Coriolis mass meter shown in FIG. 4.

In Fig. 4, the grout material to be pumped enters the device from the inlet feed pipe 10, is divided into vibrating pipe bodies 11a and 11b provided in parallel in the device, and then joins again at the outlet side of the device. and is delivered to a predetermined injection location.

The vibrating tube bodies 11a, llb are the vibrating tube bodies 11a,
An excitation coil 13 attached to a protective pipe 14 surrounding the llb causes the grout to vibrate slightly at a resonant frequency of opposite phase when the grout is not being fed or is stopped, as shown in FIG. It has become.

The vibrating tube bodies 11a and 11 vibrate slightly in this opposite phase state.
b is not subjected to the Coriolis force, so a constant vibration state is maintained, but as the grout material passes through the vibrating tubes 11a, 11b, the vibrating tubes 11a, l
lb is subjected to the Coriolis force, and as shown in FIG. 7, a phase difference is generated in the vibrations at its input and output sides. Since this phase difference is proportional to the mass flow rate, the mass flow rate (kg/ll1in) is measured by detecting this phase difference using the optical sensors 12a and 12b.

〔Example〕

Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples.

FIG. 3 is a diagram showing the injection flow of grouting material for dam grouting and the like.

In FIG. 3, grout materials are mixed and mixed in a plant (not shown) and then placed in a grout container 1. The grout material contained in the grout container 1 is delivered via a transport pump 2 to a grout feed pipe 3 to an injection location.

On the outlet side of the transport pump 2, a grout feed pipe 3 is provided.
A return pipe 4 returning to the container 1 is provided with a three-way valve 5.
is provided. Further, on the downstream side of the three-way valve 5,
An electromagnetic flowmeter 6, a pressure gauge 7, and a Coriolis mass flowmeter 8 (hereinafter simply referred to as a mass flowmeter) as a density meter are provided in close proximity, and constitute a detection section F.

Measurement data from the electromagnetic flowmeter 6, pressure gauge 7, and mass flowmeter 8 of the detection section F is sent to a recorder 9 and recorded.

With the grouting equipment as mentioned above, the water-cement ratio,
That is, the grout density measurement accuracy and the flow rate measurement accuracy using a mass flowmeter were tested while varying the density.

The test was carried out using a grouting pressure crab P = 10 kg/c.
Under the condition of m2, Case 1 is the case of only water (ρ=
Ig/ci+3), and in case 2, the water-cement ratio is W/
When C=8/1 (ρ=1.045 g/cm”),
Case 3, where the water-cement ratio is W/C=2/1 (
Three types of grout materials with ρ = 1.255 g/cm”) were pumped, and the measured values with an electromagnetic flowmeter were 0.5, 10, and 20.
．． The mass flow rate and density measurement value measured by the mass flow meter at the time of 301/win were plotted.

The test results are shown in FIGS. 1 and 2. In FIG. 1, the vertical axis shows the density value (g/cm3) measured by the mass flowmeter, and the horizontal axis shows the flow rate value (i/win) measured by the electromagnetic flowmeter. In addition, in Figure 2, the vertical axis is the measured value by the mass flowmeter (
kg/■in), and the horizontal axis shows the flow rate measured by an electromagnetic flowmeter (j!/win).

Regarding the accuracy of density measurement, as is clear from FIG. 1, it was found that the grout density value always showed a substantially constant value regardless of the change in flow rate and could be measured with high accuracy.

On the other hand, regarding the mass flow rate accuracy shown in FIG. 2, the mass flow rate value should originally be the volumetric flow rate x density, but this relational expression is not satisfied for the grout material.

However, since the mass flow rate at each flow rate value is plotted on a straight line, it is possible to measure the mass flow rate by multiplying by a correction coefficient.

〔Effect of the invention〕

As described in detail above, according to the present invention, grout density can be measured at low cost and with high precision by density measurement using a Coriolis mass meter, and at the same time, it does not require the troublesome handling and management of the RI density meter. It becomes possible to measure grout density without feeling it.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the test results in the example, Figure 3 is a diagram showing the grout injection flow in the example, Figure 4 is a diagram showing a Coriolis mass meter, and Figure 5 is a diagram showing the grout injection flow in the example. Figure showing the vibrating tube part of the Coriolis mass meter, No. 6
The figure is a diagram showing the state of vibration of the vibrating tube when the pumping of grout material is stopped, and FIG. 7 is the diagram of the state of vibration of the vibrating tube when the pumping of grout material is stopped. 1... Grout container, 2... Transport pump, 3...
Grout feed pipe, 4... Return pipe, 5... 3-way valve, 6... Electromagnetic flow meter, 7...-Pressure gauge, 8... Coriolis mass flow meter, 9... Record total, lla, llb・
... Vibration tube body, 12a, 12b... Optical sensor, 13.
...Exciting coil, 14...Protection pipe Patent applicant Front Engineering Co., Ltd. candle

Claims (2)

[Claims] (1) Two tubes are arranged in parallel, and an excitation coil causes both tubes to vibrate slightly at resonant frequencies in opposite phases, and then feeds grout material to both tubes. A method for measuring the density of a grout material, characterized in that the grout density is measured by using an optical sensor to detect the phase difference between the inlet side and the outlet side of both the pipe bodies. (2) In the detection unit for grout injection management consisting of a flow meter, a pressure gauge, and a density meter arranged adjacent to the middle of the grout injection line, a Coriolis mass flow meter is used as the density meter. Features a grout injection management system.