JP2673039B2 - Viscosity measuring device for muddy water in shield machine - Google Patents

Description

The present invention relates to a viscosity measuring device for muddy water in a shield machine.

[Prior Art] As is well known, in the muddy water shield, the earth and sand taken into the chamber scraped by the cutter is agitated with the muddy water supplied through the mud pipe, and externally passed through the mud pipe. Is discharged to.

In such a muddy shield, it is necessary to make the muddy water function as a stabilizing liquid in the shield chamber and the drainage pipe. Therefore, for example, an additive containing bentonite fine powder as a main component is mixed in the muddy water supplied from the mud pipe to the shield chamber. As a result, the stable liquid (muddy water) supplied via the mud pipe functions to maintain the stability of the face in the shield chamber, and the stable liquid and the earth and sand shaved by the cutter are stirred and mixed. The slurry is discharged to the outside via a drain pipe. At this time, the stabilizing liquid functions to wrap the earth and sand particles, prevent ionization, and reduce the specific gravity thereof. Therefore, the slurried earth and sand flows satisfactorily without settling in the mud discharge pipe and is discharged to the outside.

By the way, the mud supplied to the shield chamber is
In order to function sufficiently as a stabilizer, the viscosity of the stabilizer must be
It is extremely important to control the specific gravity and the like to appropriate values according to the situation.

The conventional viscosity measurement was carried out by a measurer pumping mud water each time and using a funnel viscometer as shown in FIG.

In the measurement procedure at this time, first, a measurer places the funnel-shaped container 12 on the stand 10 and presses the lower opening 12a with a finger. Next, the stabilizing solution pumped up from the muddy water supply device was passed through a wire net of 0.25 mm to remove solid matter having a particle size of 0.25 mm or more,
Fill container 12 with 500cc.

Next, the finger of the lower mouth 12a held by the measurer is released. At this time, a stopwatch measures the time until all the 500 cc of muddy water flowing out from the funnel-shaped container 12 flows into the container 14 placed at the bottom. Then, the viscosity of the muddy water is obtained from the correspondence relationship between the viscosity of the muddy water and the measurement time.

[Problems to be Solved by the Invention] However, such a conventional viscosity measurement technique has the following problems.

First, in this conventional technique, the viscosity of the muddy water is manually measured by a measurer. For this reason, there is a problem that the measurement takes time and labor, and the measurement accuracy greatly varies depending on the measurer.

Moreover, in such a conventional technique, the viscosity of the muddy water supplied through the mud pipe cannot be continuously measured in real time. For this reason, when the properties of the stabilizing liquid suddenly deteriorate during the excavation by the shield excavator, there is a problem that this is detected in real time and the viscosity thereof cannot be controlled to an appropriate value.

Further, since the measurement work is performed on site, there is a problem that the measuring device is easily soiled, cleaning and storage are troublesome, and the stabilizing solution can be managed only by the funnel viscosity.

For this reason, the conventional viscosity measurement technique cannot automate the shield work and save labor, which has been a major obstacle to the centralized management of the shield machine by the computer.

The present invention has been made in view of such conventional problems, and an object thereof is a shield machine capable of automatically and accurately measuring the viscosity of mud water used as a stabilizing liquid in real time. To provide a viscosity measuring device for muddy water.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a shield excavation for supplying muddy water to a shield chamber via a mud pipe and discharging muddy water in the shield chamber via a mud pipe. In the machine, a pressure measuring device which is provided in at least one of the mud sending pipe and the mud sending pipe and measures the pressure of the mud water flowing in the pipe line at at least two points, and the differential pressure of the mud pressure and the mud viscosity in advance. And a viscosity calculating means for calculating the funnel viscosity of the muddy water based on the measured differential pressure of the muddy water pressure.

[Operation] The present invention focuses on the fact that when a fluid flows in a pipeline, a pressure difference is generated corresponding to the funnel viscosity of muddy water in the pipeline, and the funnel viscosity of the fluid is calculated from this pressure difference. It is characterized by doing. The funnel viscosity is the viscosity measured by the funnel viscometer shown in FIG. 11 as described above, and is often used as a management reference value for muddy water in the shield construction method.

Specifically, for example, under a certain design condition, the correlation between the friction loss head h and the funnel viscosity F is experimentally measured, and based on the measured mud pressure difference, that is, the friction loss head h. The funnel viscosity F is obtained using the above correlation.

Thus, the funnel viscosity of the mud flowing in the mud pipe or the mud pipe can be automatically measured in real time.

In particular, in the recent shield construction method, the shield excavator is centrally managed by a computer. Therefore, the measuring device according to the present invention, which can accurately grasp the funnel viscosity of the muddy water supplied to the inside of the shield chamber in real time, is extremely favorable as the sensor part of the computer.

[Example] Next, an example of calculating the viscosity using a hydraulic formula, and an example of calculating the funnel viscosity using a correlation between the differential pressure of the previously measured muddy water and the funnel viscosity (implementation of the present invention) Example) will be described with reference to the drawings. FIG. 1 shows an example of a commonly used muddy water shield machine.

In this shield machine, as shown in FIG. 1B, a partition 12 is provided in the front part of the shield 10, and a sealed space isolated from the tunnel yard 24 is provided as a shield chamber 14 on the face 22 side of the partition 12. Is forming.

As shown in FIG.
The mud pipe 16 and the mud pipe 18 are connected. Then, the muddy water 100 sent from the muddy water treatment plant 30 provided outside the tunnel using the water feed pumps P ₁ and P ₂ is the mud pipe 16
Is supplied to the shield chamber 14 via. This muddy water
The muddy water delivered from the muddy water treatment plant 30 is mixed with an additive containing bentonite fine powder as a main component, for example, so that 100 functions as a stabilizing solution in the shield chamber.

FIG. 1C shows a part of the internal configuration of the muddy water treatment plant 30. This muddy water treatment plant 30 is a muddy water treatment device.
30a, adjusting tank 30b, fresh water supply device 30c, thickener supply device 30d
including. Then, the muddy water treatment device 30a removes sediment from the muddy water returning via the mud discharge pipe 18, and after performing various treatments such as adjusting the pH, the muddy water is adjusted in the adjusting tank 30b.
Supply to

The fresh water supply device 30c supplies fresh water to the adjusting tank 30b, and the thickener supplying device 30d includes the adjusting tank 3b.
Supply fine powder of bentonite etc. to 0b. Thus, in the adjusting tank 30b, the viscosity, specific gravity and other properties of the muddy water are adjusted so that the muddy water functions as a good stabilizing liquid, and the muddy water is supplied to the shield chamber 14 via the mud sending pipe 16.

The cutting face 22 is excavated by the rotary cutter 20 which is rotationally driven by a drive device (not shown). The earth and sand scraped off is taken into the shield chamber 14. In the chamber 14, the taken in sand and sand are stirred with the mud water 100 that functions as a stabilizing liquid, flow into the mud pipe 18 as slurry mud, and are further discharged by the functions of the mud pumps P ₃ and P _4. It flows in the mud pipe 18 and flows toward the mud water treatment plant 30. At this time, in the slurry muddy water 100, the particles of earth and sand are surrounded by the stabilizing liquid, their ionization is prevented, and the specific gravity is kept light.

For this reason, the sediment particles flow smoothly in the sludge pipe 18 without settling, that is, without causing the above.

What is important in this is to keep the viscosity of the muddy water 100 supplied to the shield chamber 14 through the mud pipe 16 at a value that sufficiently functions as a stabilizing liquid.

The feature is that when a viscous fluid flows in the pipeline, a certain pressure difference is generated in the pipeline, and by measuring this pressure difference, the viscosity of the muddy water 100 is automatically measured in almost real time. It is possible.

For this reason, at least two pressure measuring devices 40a and 40b are provided in the mud sending pipe 16, and the pressures Pa and pb of the mud water 100 are measured at at least two points in the pipe line 16.

It is preferable that these pressure measuring devices 40a and 40b are provided at a predetermined interval l in the straight pipe portion of the mud pipe 16 as shown in FIG. 3 (A). In the embodiment, 1 is set to 10 m.

FIG. 3 (B) shows a pressure measuring device used in this embodiment.
Forty specific configurations are shown. Example pressure measuring device
Reference numeral 40 includes a flange 42 sealed by liquid sealing, a detecting unit main body 44 including a pressure detecting unit, and a tube 46 for conducting the sealed liquid between the two.

The flange 42 has a diaphragm 41 attached to the mud water 100 flowing in the mud pipe 16 so that the pressure of the mud water 100 flowing in the mud pipe 16 changes with the pressure of the enclosed liquid via the diaphragm 41. Appears, and this is detected by the pressure detection unit of the detection unit main body 44 via the tube 46. This pressure detecting section is preferably formed using a strain gauge made of silicon or the like.

In the embodiment, as shown in FIG. 3 (A), in order to equalize the pressure loss in the tubes 46a, 46b of the pressure detectors 40a, 40b, the respective detection bodies 44a, 44b are provided with the flange 42.
It is located almost in the middle of the installation position of a and 42b. As a result, even if there is a pressure loss in the tubes 46a and 46b, this is uniformly canceled, and the differential pressure between both measurement points can be accurately obtained.

Between the pressures Pa and Pb measured using the two pressure measuring devices 40a and 40b configured in this way and the head loss h per unit length of the muddy water 100 in the pipe line 16 is represented by the following formula. I have a relationship.

h = (Pa−Pb) / l (10 ″) l; The distance between the pressure measuring devices 40a and 40b provided in the straight pipe portion.

Therefore, by substituting the pressures Pa and Pb detected by the pressure measuring devices 40a and 40b into (10 ″), the head loss h (differential pressure) of the muddy water 100 in the mud pipe 16 can be accurately obtained. .

The head loss h is generally expressed by the following equation in the horizontal portion of the straight pipe.

Therefore, if the velocity v of the muddy water 100 and the inner diameter d of the muddy water pipe 16 are known, the pipe friction coefficient λ of the muddy water pipe 16 can be obtained from the equation (10).

The pipe friction coefficient λ has the relationship shown by the following equation with the Reynolds number Re of the muddy water 100 described above.

Brasius equation (3 × 10 ³ ≤ Re ≤ 10 ⁵ ) λ = 0.3164Re ^−0.25 (11) Nikulase equation (10 ⁵ ≤ Re ≤ 3 × 10 ⁶ ) λ = 0.0032 + 0.221Re − ^0.237 (12) Therefore, When the pipe friction coefficient λ of the mud pipe 16 is obtained from the above equation (10), the Reynolds number Re of the mud water 100 is obtained from the above (11), (1
2) It can be calculated backward from the equation.

Also, the Reynolds number R of 100 muddy water thus obtained
e is generally represented by the following equation.

Re: Reynolds number v: Flow velocity (m / s) d: Inner diameter of pipe (m) ν: Kinematic viscosity (m ² / s) Therefore, Reynolds number Re of muddy water 100 can be calculated from Eq. (11) or (12) above. Find this Reynolds number Re and muddy water 100
By substituting the flow velocity v and the inner diameter d of the mud pipe 16 into the equation (13), the kinematic viscosity coefficient ν of the muddy water 100 can be obtained.

At this time, between the kinematic viscosity coefficient ν and the viscosity coefficient μ of the muddy water 100, there is a relationship expressed by the following equation using the muddy water density ρ as a parameter. This is shown in the diagram in FIG.

ν: Dynamic viscosity coefficient (m ² / s) μ: Viscosity coefficient (kgf * s / m ² ) ρ: Fluid density (kgf / m ² ) Therefore, obtain the kinematic viscosity coefficient ν and muddy water density ρ. Thus, the viscosity coefficient μ of the muddy water 100 can be calculated.

As described above, by measuring the pressure of the muddy water 100 flowing in the mud pipe 16 with the pressure measuring devices 40a and 40b at at least two points, the viscosity of the muddy water 100 can be calculated in real time.

By the way, among the coefficients of the above equations, the inner diameter d of the mud pipe 16 is
The flow velocity v, density ρ, and the like of the muddy water 100 can be obtained in advance by measurement.

However, the flow velocity v and the density ρ of the muddy water 100 are not always constant. In this embodiment, in order to enable more accurate measurement, the mud pipe 18 is provided with a flow velocity / density measuring device 50.
The flow velocity V and density ρ of the muddy water 100 flowing in 16 are detected in real time. Therefore, by substituting the flow velocity V and the density ρ of the muddy water 100 thus obtained into the above equations, the viscosity of the muddy water 100 can be measured more accurately.

FIG. 4 shows a specific structure of the flow velocity / density measuring device 50. The measuring device 50 of the embodiment is a pair of ultrasonic receivers arranged on the side wall of the mud transport pipe 16 so as to face each other at a predetermined angle θ with respect to the flow method of the muddy water 100 flowing therein.
52 and 54, and a calculation unit 56 that calculates the flow velocity and the density.

The computing unit 56 includes the pair of ultrasonic transceivers.
52, 54 is used to measure the flow velocity v of the muddy water 100 flowing in the mud pipe 16 as follows. That is, the propagation velocity C of ultrasonic waves in a stationary liquid is
If the liquid type, temperature, and pressure are fixed, it will be a constant value,
When a liquid flows, it changes according to the direction of the flow and the flow velocity. For example, if the flow direction and the ultrasonic wave propagation direction are forward, the ultrasonic wave propagation velocity increases by the flow velocity, and if the flow direction is opposite, it decreases by the flow velocity.

Therefore, the arithmetic unit 56 is configured to include the pair of ultrasonic transceivers.
52 and 54 are mutually driven to transmit and receive an ultrasonic pulse, and a forward propagation time t ₁ and a backward propagation time t ₂ with respect to the flow of the muddy water 100 are measured. Propagation time obtained at this time
It is known that t ₁ and t ₂ have the following relationship with the flow velocity V of the muddy water 100.

From equations (6) and (7) However, v = flow velocity (m / s) L = distance between transmitter and receiver (m) θ = angle formed by ultrasonic propagation axis and central axis of pipe C = propagation velocity of ultrasonic waves in stationary mud (m / s) The calculation unit 56 substitutes the measured propagation times t ₁ and t ₂ into (8) to calculate and output the flow velocity v of the muddy water 100 flowing in the mud pipe 16 in real time.

In this case, as can be seen from the equations (8), the relationship between the reciprocal of the propagation time and the flow velocity is linearly proportional, and its linearity is very good. ), Since the term of the ultrasonic wave propagation velocity C included in the equation (7) is deleted, the flow velocity v can be obtained regardless of the type, temperature and pressure of the muddy water.

In addition, the calculation unit 56 of the embodiment measures the density ρ of the muddy water 100 flowing in the mud pipe 16 as follows using the pair of ultrasonic transceivers 52 and 54.

That is, when a harmonic wave is transmitted and received between the pair of ultrasonic wave receivers 52 and 54, the transmitted ultrasonic wave is attenuated due to scattering and viscosity at the particle interface of the muddy water 100 and internal friction of the particles.

FIG. 5 (A) shows a rectangular pulse of ultrasonic waves transmitted from the ultrasonic transmitter / receiver 52 to the muddy water 100, and FIG. 5 (B) shows ultrasonic waves received by the ultrasonic transmitter / receiver 54. The transmission waveform of is shown. As shown in the figure, it can be understood that the ultrasonic wave transmitted toward the muddy water 100 is received after being attenuated in the muddy water.

At this time, since the density ρ of the muddy water 100 and the attenuation amount of the ultrasonic wave have a predetermined correspondence relationship, the density ρ of the muddy water 100 can be obtained by measuring the attenuation amount of the received ultrasonic wave.

6 and 7 show measurement data of the concentration of solid matter contained in the muddy water and the attenuation rate of ultrasonic waves passing through the muddy water. FIG. 6 shows the data when kaolin is mixed in the muddy water, and FIG. 7 is the data when lime and gypsum are mixed in the muddy water.

As is clear from these measurement data, the amount of ultrasonic attenuation has a proportional relationship with the solid concentration in mud water. Therefore,
By transmitting and receiving ultrasonic waves in the muddy water 100 as shown in FIG. 5, the muddy water 100 is calculated based on the attenuation of the received ultrasonic waves.
The density ρ (volume concentration of the amount of dry sand contained in 100 muddy water) can be measured in real time. At this time, the concentration of muddy water is accurately measured without being affected by the color, pH, conductivity, etc. of the muddy water, or even when it contains heterogeneous suspended particles such as solids and emulsified particles. It becomes possible.

Next, in order to verify the effect of the present invention, the pipe diameter d = 20 cm
The circular tube path, v = 1.82m / sec (approximately at a flow rate in terms of 3.4 m ³ / min)
Muddy water 100 (stabilizing liquid) was supplied at the flow rate of
An explanation will be given assuming that the pressure in the pipe is measured by setting the interval.

First, set an appropriate value of h and calculate λ and Re back,
The case where the kinematic viscosity coefficient ν is calculated by substituting this into the equation (13) will be described.

Substituting each of the above constants into equations (10 ') and (13), λ,
ν is represented by the following equation.

With this, if the design conditions (d, l, v, ρ) are determined, λ, Re can be determined by measuring the head loss h, that is, the differential pressure of the mud flowing in the pipe, and by this, the kinematic viscosity can be determined. It is understood that the coefficient and the viscosity coefficient can be calculated back.

According to the test results, within the range of practical design conditions, the loss head h and logv had a substantially linear relationship as shown in FIG.

FIG. 8 shows a specific circuit configuration of the shield machine of this embodiment.

In the present embodiment, the pressures Pa and Pb of the muddy water 100 detected by the two pressure measuring devices 40a and 40b and the velocity v and the density ρ of the muddy water 100 detected by the flow velocity / density measuring device 50 are respectively calculated by the viscosity calculation circuit 60. Is output to.

In this case, the correspondence between the differential pressure h of the muddy water 100 and its viscosity is remarkable in the direct portion of the mud pipe 16. For this reason, the pressure measuring devices 40a and 40b of the embodiment are provided in the straight line portion of the mud pipe 16 at a constant interval l.

The viscosity calculation circuit 60 includes a differential pressure calculation unit 62, a memory 64, and a viscosity calculation unit 66.

The memory 64 stores constants shown in the equations (10) to (14), that is, data such as the distance 1 between the pressure measuring devices 40a and 40b and the inner diameter d of the mud pipe 16.

Then, the differential pressure calculation unit 62 substitutes the detected pressures Pa and Pb of both pressure measuring devices 40a and 40b and the constant l read from the memory 64 into the formula (10 ″), and flows in the mud pipe 16. The head loss h of muddy water is calculated, and the calculation result is output to the viscosity calculation unit 66.

Then, the viscosity calculation unit 66 uses the data stored in the memory 64 and the head loss h, the flow velocity v, and the density of the muddy water 100 that are measured in real time using the pressure measuring devices 40a and 40b, the flow velocity / density detection device, and the like. By substituting ρ into the equations (10) to (14), the viscosity coefficient μ of the muddy water 100 flowing in the mud pipe 16 is calculated in real time, and the calculated value is output to the central control unit 70. .

The central control unit 70 compares the viscosity coefficient μ of the muddy water 100 thus measured in real time with a desired reference value,
It is judged whether the viscosity coefficient μ of the muddy water 100 is appropriate.

Then, the viscosity of the measured muddy water 100 is always the optimum value, the fresh water supply device 30c of the muddy water treatment plant 30 and the thickener supply device 30b are controlled, and an additive added to the muddy water 100, for example, bentonite fine. The amount of powder is feedback controlled.

In this way, the viscosity of the muddy water 100 supplied to the shield chamber 14 can be automatically measured / controlled in real time and feedback-controlled so that the viscosity is always optimum.

Next, an example in which the funnel viscosity is calculated by using the correlation between the differential pressure of muddy water and the funnel viscosity measured in advance, that is, an example of the present invention will be described.

FIG. 10 shows the correlation between the friction loss head h and the funnel viscosity F thus obtained, and the correlation between the two is almost linear as shown in FIG. The calculated value in the case of passes. In this case, if d, l, and v change, it is expected that a straight line of f = αh + β will be obtained.

Therefore, the friction loss head h in the pipe can be measured, and the funnel viscosity F can be obtained by using the correlation based on the measured friction loss head h.

Further, in the above-mentioned example, the case where the one containing bentonite fine powder as the main component was used as an additive to muddy water was described as an example, but the present invention is not limited to this, and stability using an additive other than this It can also be applied to the case of measuring the viscosity of a liquid, for example, a polymer-based stabilizing liquid containing CMC water-soluble polymer as a main component.

Further, in the above embodiment, the case where the viscosity measuring device is provided in the mud pipe is described as an example, but the present invention is not limited to this,
If necessary, for example, it may be provided in the sludge pipe.

[Effects of the Invention] As described above, according to the present invention, the viscosity measurement of mud water in a muddy water shield machine capable of automatically and in real time measuring the funnel viscosity of muddy water supplied as a stabilizing liquid. The effect is that the device can be obtained.

In particular, in the recent shield construction method, the shield machine is centrally controlled by a computer. However, a measuring device capable of accurately grasping the funnel viscosity of the supplied mud water in real time as in the present invention is used as a sensor part of the computer. It will be extremely effective.

[Brief description of the drawings]

1 (A), (B), and (C) are explanatory views showing an example of a commonly used mud-water shield excavator, and FIG. 2 shows the relationship between the kinematic viscosity coefficient of a fluid and the viscosity coefficient. The characteristic diagram shown in FIGS. 3 (A) and 3 (B) is an external view showing the specific structure of the pressure measuring device used in the present embodiment, and FIG. 4 is the flow velocity used in the present embodiment. FIG. 5 is an explanatory diagram showing an example of the density measuring device, FIG. 5 is a waveform explanatory diagram of ultrasonic waves transmitted / received to muddy water, and FIG. 5 (A) is an explanatory diagram of ultrasonic pulses transmitted to muddy water, FIG. 6B is an explanatory diagram of the waveform of ultrasonic waves attenuated in muddy water, FIGS. 6 and 7 are explanatory diagrams showing an example of the correlation between the muddy water density and the ultrasonic wave attenuation rate, and FIG. FIG. 9 is an explanatory diagram showing a concrete circuit configuration of the present embodiment, and FIG. 9 is a Reynolds number calculated by using a hydraulic formula, a pipe friction coefficient, and a head loss. And FIG. 10 is an explanatory diagram showing the relationship between the head loss h and the funnel viscosity F, and FIG. 11 is an explanatory diagram showing an example of a conventional viscosity measuring device. 40a, 40b ... pressure measuring device, 50 ... flow velocity / density measuring device, 60 ... viscosity calculation circuit, 100 ... muddy water.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Iwai 1-514, Honda-cho, Chiba-shi, Chiba (56) Reference JP-A-1-116193 (JP, A) JP-A-61-57833 (JP, A) JP-A 64-26123 (JP, A)

Claims (1)

(57) [Claims] 1. A shield machine for supplying mud water to a shield chamber via a mud pipe and discharging mud water from the shield chamber via a mud pipe. At least one of the mud pipe and the mud pipe. A pressure measuring instrument installed in the pipe to measure the pressure of the muddy water at least at two points, and the correlation between the differential pressure of the muddy water and the funnel viscosity of the muddy water is stored in advance, and the measured muddy pressure is measured. A viscosity measuring device for a shield machine, comprising: viscosity calculating means for calculating the funnel viscosity of the muddy water based on the differential pressure of the muddy water.