JPH04209294A - Viscosity controller of mud slurry in shielding excavator - Google Patents

Abstract

PURPOSE:To control viscosity of a mud slurry in a real time, by measuring the pressure difference of the mud slurry in a pipe to calculate the viscosity of the mud and feeding a viscosity-increase agent according to the calculated figure. CONSTITUTION:A viscosity controller 60 is provided in a slurry pipe 16 to a shield chamber 14. Next, pressure gauges 40a, 40b are provided in a slurry discharge pipe 18 or a pipe 16 to measure the difference pressure of the mud slurry 100. Next, a velocity/density detector 50 is provided on the same pipe to measure the velocity and the density of the mud slurry 100. And in accordance with these measured data, the viscosity of the mud slurry 100 is calculated almost in a real time. Moreover, in accordance with these data, the pump 64 of controller 60 is regulated to feed a specified volume of bentonite or the like within a viscosity-increase agent feeder 62 to the slurry pipe 16. In this way, the viscosity of the slurry 100 is controlled without time lag and the mud slurry is used to serve as a stabilizing liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for controlling the viscosity of mud in a seal l-excavation machine.

[Prior art] As is well known, in muddy water seals, sand is scraped off by a cutter and taken into a chamber, mixed with muddy water supplied through a mud feeding pipe, and then pumped outside through a mud draining pipe. is discharged to.

In a muddy water type shield like the second one, it is necessary to make the muddy water function as a stabilizing liquid in the shield chamber and the mud drainage pipe. For this reason, the muddy water supplied from the mud feeding pipe to the shield chamber and bar is mixed with an additive or a thickening agent, for example, containing fine hentonite powder as a main component. As a result, the stabilizing liquid (muddy water) supplied via the mud pipe functions to maintain the stability of the face inside the shield chamber, and the second stabilizing liquid and the earth and sand scraped off by the cutter are stirred and mixed. The slurry is then discharged to the outside through a slurry pipe. At this time, the stabilizing liquid functions to envelop the earth and sand particles, prevent ionization, and reduce their specific gravity. For this reason, the slurry-formed earth and sand flows smoothly in the mud draining pipe without settling and is discharged to the outside.

By the way, in order for the muddy water supplied to the shield chamber to function sufficiently as a stabilizing liquid, it is extremely important to control the viscosity, specific gravity, etc. of the stabilizing liquid to appropriate values depending on the situation.

For this reason, in conventional devices, the viscosity of the muddy water is measured using a funnel viscosity 81 as shown in Fig. 12 by pumping up the muddy water each time using a measuring device, and controlling the viscosity of the muddy water based on the measurement results. Ta.

The measurement procedure at this time is to first place the strawberry-shaped container 2 on the measuring tool stand 1 and press the lower opening 2a with a finger. next,
Stabilizing liquid pumped up from muddy water supply device at 0.25m+s
After passing through a wire mesh to remove solids with a particle size of 025I or more, the container 2 is filled with 500 cc.

Next, release the finger on the lower opening 2a that is being held down by the measuring tool. At this time, a stopwatch is used to measure the time taken for all 500 cc of muddy water to flow out of the container 2 and fall into the container 4 placed at the bottom. Then, the viscosity of the muddy water is determined from the correspondence between the viscosity of the muddy water and the measurement time.

[Problems to be Solved by the Invention] However, such conventional viscosity control technology has the following problems.

■ In this conventional technology, the viscosity of muddy water is measured manually using a measuring tool. For this reason, not only is the measurement time-consuming and labor-intensive, but the measurement accuracy varies widely depending on the measuring tool, and there is a problem that only accurate viscosity control is possible.

■ Furthermore, with such conventional technology, it is not possible to continuously measure the viscosity of mud water supplied through the mud pipe in real time. Therefore, when the properties of the stabilizing liquid deteriorate rapidly during excavation by the shield tunneling machine, there is a problem in that it is not possible to detect this in real time and control the viscosity to an appropriate value.

The present invention was made in view of such conventional problems, and its purpose is to accurately feedback control the viscosity of muddy water supplied to the shield chamber in real time so that it functions sufficiently as a stable liquid. An object of the present invention is to provide a device for controlling the viscosity of muddy water in a shield tunneling machine.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a shield excavation system that supplies muddy water to the shield chamber through a mud feeding pipe and discharges muddy water in the shield chamber through a mud draining pipe. In the machine, a pressure measuring means is provided in at least one of the mud feeding pipe or the mud draining pipe and measures the pressure of the muddy water flowing in the pipe at at least two places, and a viscosity calculation means for calculating the viscosity of the muddy water; and viscosity control means for controlling the viscosity of the muddy water supplied to the shield chamber based on the viscosity of the muddy water determined by the viscosity calculation means. [Function] The present invention focuses on the fact that when a fluid flows through a pipe, a pressure difference corresponding to the viscosity of muddy water is generated in the pipe, and the viscosity of the fluid is measured from this pressure difference.

Then, based on this measured value, the viscosity of the muddy water supplied to the shield chamber is accurately feedback-controlled in real time so that it functions sufficiently as a stabilizing liquid.

Such viscosity measurement may be performed using a predetermined hydraulic formula, or may be performed using a previously measured correlation between the differential pressure of the muddy water and the viscosity.

(a) Case in which viscosity is measured using a hydraulic formula.The case in which viscosity is measured using a predetermined hydraulic formula will be explained.

In the measuring device of the present invention, a pressure measuring device is provided in either the mud feeding pipe or the mud draining pipe in the shield chamber to measure the pressure of muddy water flowing through the pipe at at least two locations. Then, the viscosity calculating means measures the viscosity of the muddy water flowing in the pipe in real time from the pressure difference between the measured pressures (friction loss head h of the mud flowing in the pipe) using the following hydraulic formula. There is.

That is, the differential pressure of muddy water flowing in the pipe, that is, the friction head loss, is determined by the following equation (Darcy-Weisbach equation).

l v2 h-λ・□・□ (10) d 2g In addition, λ in equation (10) is the pipe friction coefficient, which generally changes depending on the Reynolds number Re and the surface roughness of the pipe wall. The value of − for turbulent flow in a hydraulically smooth circular pipe is
The following formula is proposed as a practical one.

■ Blasius formula (3X103≦Re≦105) λ=
0.3164Re-02″' ・(II)(2
' = Clara's formula (105≦Re≦3X106)λ
−0,0032+0.22] Re “0”’ −(
12) On the other hand, since the Reynolds number Re is defined by the following formula, v−d ■・d Re=−−ρ□ (13) ν μ friction jM By measuring the water loss head, the formula ( (10) is modified from (10)
), we can calculate the pipe friction coefficient λ under certain conditions.

d' 2g λ=□・・h ...(10') v2 From λ thus obtained, formula (11) or formula (12
), then the kinematic viscosity coefficient of this muddy water and the viscosity coefficient μ can be back calculated using the following equation.

-d =　　　　　　　　　・(+3’)Re Vφd μ＝ρ　□　　　・−(13’) Re In addition, r flow path length d: Pipe diameter ■＝Average flow velocity g Gravitational acceleration ρ is the fluid density.

In this way, the pipe friction coefficient is determined by substituting the differential pressure of the muddy water measured using a pressure measuring device, that is, the friction loss head, into the above (10), and this pipe Y friction coefficient is calculated as the above (+3').
, (13'), the kinematic viscosity coefficient and viscosity coefficient of muddy water can be calculated almost in real time.

(b) When measuring the viscosity using the correlation between the differential pressure of the muddy water measured in advance and the viscosity.
In addition to the case where the above-mentioned hydraulic formula is used, the correlation between the muddy water pressure differential and the muddy viscosity may be measured and stored in advance, and this correlation may be used.

For example, the relationship between friction loss head and funnel viscosity F is measured experimentally under certain design conditions, and the correlation is determined based on the measured mud water pressure difference, that is, the friction loss head. The funnel viscosity F may also be determined using In this case, it is extremely effective to define the funnel viscosity as a control reference value.

As explained in (a) and (b) above, according to the present invention, the viscosity of muddy water flowing through a mud feeding pipe or a mud draining pipe can be automatically measured in real time.

The apparatus of the present invention uses a viscosity control means to feedback-control the viscosity of the muddy water supplied to the shield chamber based on the measured values obtained as described above.

The viscosity control at this time can be performed within the muddy water treatment plant, but as the excavated tunnel becomes longer, the distance between the chamber and the muddy water treatment plant also becomes longer and the responsiveness of the control decreases.

For this reason, it is preferable that the viscosity control means is formed to supply a thickening material that increases the viscosity of muddy water to the mud feeding pipe or the shield chamber, as described in claim (2). Based on the value, it becomes possible to feedback control the viscosity of the muddy water in the chamber with good responsiveness.

In addition, when the thickener is supplied to the slurry pipe, claim (3)
), a mixer is installed directly in the mud pipe or by bypassing a part of the pipe, and the thickener supplied from the thickener supply device is mixed with the muddy water flowing inside the pipe. It is preferable to form the mixture by stirring.

This makes it possible to automatically and almost real-time feedback control the viscosity of the muddy water supplied to the shield chamber so that it functions sufficiently as a stabilizing liquid.

[Embodiments] Next, preferred embodiments of the present invention will be described in detail with reference to the drawings.

Figures 1 and 2 show a preferred example of the muddy shield excavation method to which the present invention is applied, with Figure 1 showing a schematic view of the tunnel tip, and Figure 2 A schematic diagram of the entire system is shown.

The shield excavator of the embodiment is provided with a partition wall 2 at the front of the shield 10, and a shield chamber 14 is provided on the face 22 side of the partition wall 12 to provide a sealed space isolated from the tunnel premises 24.
It is formed as

The shield chamber 14 is connected to a mud water treatment plant 30 provided outside the tunnel via a mud feed pipe 6 and a mud discharge pipe 18. This muddy water treatment plant 30
and other parts are controlled by a central control unit 32.

Then, from the muddy water treatment plant 30, a mud pump P
The muddy water]00 sent out using the mud feeding pipe]00 is supplied to the shield chamber 14 via the mud feeding pipe]6.

At this time, a viscosity control device 60 is provided in the mud feeding pipe 16 so that the muddy water 100 functions sufficiently as a stable liquid.

This viscosity control device 60 includes a thickener supply device 62, a pump 64, and a mixer 66.

The thickener supply device 62 is formed, for example, as a thickener tank filled with an additive mainly composed of fine hentonite powder, and the thickener filled in this tank is supplied to the pump 6.
4 to the mixer 66. At this time, the supply amount of the thickener is set to a desired amount by controlling the pump 64.

The mixer 66 is connected in series with the mud feeding pipe 16, and mixes the thickening material supplied by the pump 64 with the muddy water 100 and outputs the mixture. In the embodiment, the mixer 66 has a pipe structure in which plates twisted 180 degrees are arranged inside so that the left and right sides are twisted alternately, and one plate and the next plate are arranged to intersect at 90 degrees. It is formed. The muddy water passing through the pipe is divided into two parts by each pipe, and is given a swirling motion by the twisting of the plate, so that it is completely mixed with the supplied thickening material. Specifically, such a mixer is manufactured by Noritake Co., Ltd.
o,,1. A static mixer made by trJ or the like may be used.

Then, the shield excavator excavates the face 22 by rotating the rotary cutter 20 by a drive device (not shown). The earth and sand scraped off at this time is
4 and stirred with muddy water that functions as a stabilizing liquid to form a slurry. The slurry water flows into the pipe IP' 8, and then the slurry pump P2
．． P,,P.

The mud flows through the mud removal pipe 18 toward the mud water treatment plant 30.

At this time, in the slurry-formed muddy water 100, the earth and sand particles are surrounded by a stabilizing liquid, preventing their ionization and keeping their specific gravity low. For this reason,
The earth and sand particles flow smoothly through the mud drain pipe 8 without settling or causing clogging.

What is important here is to maintain the viscosity of the muddy water [00] supplied to the shield chamber 14 via the mud feeding pipe [6] at a value that allows it to function sufficiently as a stabilizing liquid.

For this reason, the apparatus of the present embodiment is equipped with a pressure measuring device 40 and a speed/density detector 50 in the mud drainage pipe]8, and based on the measured values, the viscosity of the muddy water]00 is measured almost in real time. Then, based on the measured value, the viscosity control device 60 is controlled, and the viscosity of the muddy water 100 is feedback-controlled to a value that allows it to function sufficiently as a stable liquid.

The feature of this embodiment is that the pressure measuring device 40.functions as a sensor portion as described above. The reason is that the flow rate/density detection device 50 and the viscosity control device 60 for supplying the thickener to the muddy water 00 are located relatively close to the shield chamber 14. This makes it possible to detect changes in the viscosity of the muddy water in the shield chamber 14 almost in real time, and to feedback control the detected value to an appropriate value. This is the pressure measuring device 40. velocity/density detector 50,
If the viscosity control device 60 is located far from the shield chamber 14, it will be difficult to detect changes in viscosity within the shield chamber 14 without time delay, and even if the thickener is mixed into the muddy water 100, it will be difficult to detect the change in viscosity within the shield chamber 14. This is because a time delay occurs until reaching 14, which is not preferable in terms of performing appropriate viscosity control.

In this embodiment, the pressure measuring device 40. Velocity/density detector 50. The viscosity control device 60 is configured as a control unit 200 as shown by a dashed line in FIG. shall be. In the control unit 200, telescopic tubes 34 and 36 whose lengths are adjustable are connected in series to the sludge feeding tube 16 and the sludge draining tube]8.

As the shield excavator excavates the face 22 and moves to the left in Figure 1, the trolley 26 also moves to the left in the figure, and the control unit 2
00 is always located within a certain distance. This makes it possible to always quickly respond to changes in the viscosity of the muddy water 100 within the shield chamber 14 and to perform feedbank control of the viscosity.

In this embodiment, the valves 38a and 38b are closed every time the telescoping pipes 34 and 36 extend a certain distance, and the telescoping pipes 34 and 36 are closed.
A new vibrator is connected between the telescopic pipe 36 and the valve 38a, and between the telescopic tube 36 and the valve 38b, so that the trolley 26 can move further forward (move to the left in the figure).

Next, the pressure measuring device 40 and the velocity/density detector 50
The principle of measuring the viscosity of muddy water using the following will be explained.

A feature of the present invention is that when a viscous fluid flows through the pipe, a predetermined pressure difference is generated in the pipe, and by measuring this pressure difference, the viscosity of the muddy water 100 can be determined in almost real time. The reason is that automatic measurement is possible.

For this reason, at least two pressure measuring devices 40a and 40b are provided in the mud draining pipe 18, and the pressure Pa of the muddy water 100 is measured at at least two points in the pipe line 18.

We are measuring pb.

It is preferable that these pressure measuring devices 40a and 40b be provided at a predetermined interval 1 in the straight pipe portion of the mud removal pipe 8, as shown in FIG. 3(A). In the example,! =] is set to Om.

FIG. 3(B) shows a pressure measuring device 4 used in this embodiment.
The specific configuration of () is shown. Example pressure gauge 1
The meter 40 has a flange 42 sealed by liquid filling.
, a detection section main body 44 including a pressure detection section, and a tube 46 through which sealed liquid is conducted between the two.

The flange 42 is connected to the mud draining pipe]00
It has a diaphragm 4 attached facing the sludge pipe 8, whereby the pressure of muddy water flowing inside the mud drain pipe 8 appears as a pressure change in the sealed liquid via the diaphragm 41,
This is detected by the pressure detection section of the detection section main body 44 via the tube 46. Preferably, this pressure detection section is formed using a strain cage made of silicon.

In addition, in the embodiment, as shown in FIG. 3(A), the tube 46a of each pressure detector 40a, 40b.

In order to equalize the pressure loss within 46b, each detection body 44a, 44b has a flange 42a.

It is arranged approximately in the middle of the installation position of 42b.

As a result, even if there is a pressure loss within the tubes 46a, 46b, this is uniformly canceled and the differential pressure between the fixed points on both sides can be accurately determined.

Two pressure measuring devices 40a configured in this way.

There is a relationship between the pressures Pa and Pb measured using the pipe 40b and the head loss per unit length of the muddy water 100 in the pipe line 16 as shown in the following equation.

hi (Pa-Pb) /l - (10')l
; The interval between the pressure side regulators 40a and 40b provided on the straight pipe portion.

Therefore, the detected pressure Pa of the pressure measuring devices 40a, 40b
, Pb into the above (10'), the head loss h (differential pressure) of the muddy water]00 in the mud removal pipe 18 can be accurately determined.

This head loss is generally expressed by the following formula in the horizontal section of a straight pipe.

p v 2 h −λ □ ・ □ (m) ・−(1
0) 6 2g h: Head loss of straight pipe (m) λ: Pipe friction coefficient d: Inner diameter of pipe (cm) □: Velocity head (rn) g g: 9.8 (m/s) Therefore, If the speed V and the inner diameter d of the mud removal pipe 8 are known, the pipe friction coefficient λ of the mud removal pipe 18 can be determined from the above equation (10).

This pipe friction coefficient λ has a relationship with the Reynolds number Re of the muddy water 100 described above as shown in the following equation.

■ Blasius equation (3X103≦Re≦105) λ-
0,31 [i4Re-025-(If)■ Nicklase formula (105≦Re≦3X1.06)λ-0,0032
+0.221. Re-0°"' - (12) Therefore, from the above formula (]O), the pipe friction coefficient λ of the lido main pipe]8
, we can calculate the Reynolds number Re of 100 muddy water by the above (1
・It is possible to calculate backwards from formula I) and (+2).

Further, the Reynolds coefficient Re of the muddy water 100 thus obtained is expressed by the following equation.

dv-d Rem--ρ□... (13) ν μ Re: Reynolds number V: Flow velocity (m/s) d: Inner diameter of the pipe (m) C: Kinematic viscosity coefficient (I/s) Therefore, (11) ) or muddy water 100 from equation (12)
Find the Reynolds number Re, and use this Reynolds number Re as
The flow velocity V of the muddy water 100 and the inner diameter d of the mud removal pipe 18 are as follows (13
·) By substituting into the equation, the kinematic viscosity coefficient ν of the muddy water 100 can be determined.

At this time, there is a relationship between the kinematic viscosity coefficient ν and the viscosity coefficient μ of the muddy water 100 as shown in the following equation using the muddy water density ρ as a parameter. This is illustrated in FIG. 4.

μ] v−d C□ −・・・・(2) ρ ρ
Re: coefficient of kinematic viscosity (ba/s) μ: coefficient of viscosity (kg r*s/rd) ρ: density of fluid (kgr/rT?) Therefore, find the coefficient of kinematic viscosity ν and the density ρ of muddy water. Accordingly, the viscosity coefficient 71 of muddy water]00 can be obtained by calculation.

Thus, according to the present invention, the pressure measuring devices 40a, 40
By measuring the pressure of the muddy water 100 flowing in the mud drainage pipe 18 at at least two points using b, the viscosity of the muddy water 100 can be calculated in real time.

By the way, among the coefficients in each of the above equations, the inner diameter d of the mud removal pipe 18
,′/? The flow velocity V, density ρ, etc. of the S water 100 can be determined in advance by measurement.

However, the flow velocity V and density ρ of the muddy water 100 are not always constant. In this embodiment, in order to enable more accurate measurement, the flow velocity/density measuring device 50 is provided in the deadhead pipe 18 as described above, and the flow velocity V and density ρ of the muddy water 100 flowing inside the mud removal pipe 8 are measured. Detected in real time. Therefore, by substituting the flow velocity V and density ρ of the muddy water 1[]0 obtained in this way into each of the above equations, the muddy water 1.00
It becomes possible to measure the viscosity of

FIG. 5 shows a specific configuration of the flow velocity/density measuring device 50. As shown in FIG. The measuring device 50 of the embodiment includes a pair of ultrasonic transmitters and receivers 52 and 54 that are disposed on the side wall of the mud drainage pipe 18 to face each other at a predetermined angle θ with respect to the flow direction of the muddy water 100 flowing inside the pipe, and and a calculation unit 56 that calculates density.

Then, the calculation unit 56 uses the pair of ultrasonic transceivers 52 and 54 to calculate the muddy water flowing inside the mud removal pipe 18]00
The propagation velocity C of ultrasonic waves in a stationary liquid will be a constant value if the type, temperature, and pressure of the liquid are determined, but if the liquid is flowing, the flow velocity V will be measured as follows. It changes depending on the direction and flow velocity. For example, if the flow direction and the ultrasonic propagation direction are in the forward direction, the propagation velocity of the ultrasonic wave increases by the flow velocity, and if the flow direction is in the opposite direction, it decreases by the flow velocity.

Therefore, the calculation unit 56 alternately drives the pair of ultrasonic transceivers 52 and 54 to transmit and receive ultrasonic pulses, and the propagation time t in the forward direction with respect to the flow of muddy water]00.
The propagation time t2 in the opposite direction is measured. The propagation time tl + t2 obtained at this time is the flow velocity V of the muddy water 100,
It is known that the following relationship exists.

1, = □ ・(6) C+vcosθ 12= □ ・・(7) C−vcosθ (Left below) From equations (6) and (7), L ] ]v
= −(−m−)−<8) 2 cosθ 1. 1
Also, ■ = flow velocity (m/5) L = distance between transmitter and receiver (m) θ - angle between the ultrasonic propagation axis and the central axis of the pipe C - propagation speed of ultrasonic wave in stationary mud water (m /s) and the calculation unit 56
is a fixed propagation time of 1 bale, 1, . By substituting 12 into the above (8), the flow velocity V of the muddy water]00 flowing inside the mud removal pipe 18 is calculated and output in real time.

In this case, as can be seen from each equation (8) above, the relationship between the difference in the reciprocal of the propagation time and the flow velocity is a linear proportional relationship, and its linearity is very good. )
, (7) is eliminated, the flow velocity V can be determined regardless of the type, temperature, and pressure of the muddy water.

Further, the calculation unit 56 of the embodiment uses the pair of ultrasonic transmitters and receivers 52 and 54 to generate the muddy water 10 flowing inside the p1 mud pipe 18.
(The density ρ of 1 is measured as follows.

That is, when ultrasonic waves are transmitted and received between a pair of TFI sound wave transmitters and receivers 52 and 54, the transmitted ultrasonic waves are transmitted through muddy water 100.
is attenuated by scattering at particle interfaces and internal friction of the viscous particles.

In FIG. 6(A), muddy water 100 is transmitted from the ultrasonic transmitter/receiver 52.
The rectangular pulse of the transmitted ultrasonic wave is shown in the direction shown in the same figure (
B) shows the received waveform of the ultrasound received by the ultrasound transmitter/receiver 54. As shown in the figure, it will be understood that the ultrasonic waves transmitted toward the muddy water are received after being attenuated in the muddy water.

At this time, since there is a predetermined correspondence between the density ρ of muddy water]00 and the amount of attenuation of the ultrasonic wave, the density ρ of muddy water 1.00 can be found by measuring the amount of attenuation of the received ultrasonic wave. .

7 and 8 show measurement data of the concentration of solids contained in muddy water and the attenuation rate of ultrasonic waves passing through this muddy water. FIG. 7 shows data when kaolin is mixed into muddy water, and FIG. 8 shows data when lime and gypsum are mixed into muddy water.

As is clear from these measurement data, the amount of attenuation of ultrasonic waves has a proportional relationship with the solid matter concentration in muddy water. Therefore, as shown in FIG. 6, by transmitting and receiving ultrasonic waves in the muddy water roller 0, the muddy water 10
The density ρ (volume concentration of the amount of dry sand contained in muddy water) can be measured in real time. At this time,
Is it possible to accurately measure the concentration of muddy water without being affected by the color, pH, conductivity, etc. of muddy water, or even when it contains heterogeneous suspended particles such as solids or emulsified particles? It becomes possible.

Next, in order to verify the effect of the present invention, the pipe diameter d = 20c
Muddy water is poured into a circular pipe of m at a flow rate of v = 1.82 m /sec (approximately 3.4 m '7 m1n in terms of flow foot)] 00 (
The following explanation assumes that a stabilizing liquid) is supplied, the interval is set to f' = 10 cm, and the pressure inside the pipe is constant.

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

By substituting each of the above constants into equation (10') and (13), λ and ν are expressed by the following equation.

20 2x980 λ-□×□ ・h +000 (182) 2 -1.1834X ] O-'X h ν=I82 x20/Re = , l, v, ρ), λ and Re can be determined by measuring the head loss h, that is, the differential pressure of the muddy water flowing in the pipe, and from this it is possible to back-calculate the kinematic viscosity coefficient and viscosity coefficient. It is understood that

According to the test results, within the range of practical design conditions, the head loss and logv had a nearly linear relationship as shown in Figure 9.

FIG. 10 shows a specific circuit configuration of the shield tunneling machine of this embodiment.

In this embodiment, there are two pressure measuring devices 40a.

The pressures Pa and Pb of the muddy water detected by the muddy water 40b and the velocity V and density ρ of the muddy water 100 detected by the flow velocity/density measuring device 50 are respectively outputted to the viscosity calculation circuit 7 [ ].

In this case, the correspondence between the differential pressure of muddy water]00 and its viscosity is remarkable in the straight portion of the mud draining pipe 18.

For this reason, the pressure measuring devices 40a and 40b of the embodiment are provided on the straight portion of the mud removal pipe 18 at a constant interval E.

The viscosity calculation circuit 70 includes a differential pressure calculation section 72. memory 74
and a viscosity calculating section 76.

The memory 74 stores the constants shown in equations (10) to (14), that is, the distance between the pressure measuring devices 40a and 40b! , data such as the inner diameter d of the sludge drain pipe] 8 are stored.

The differential pressure calculation unit 72 includes pressure measuring devices 40a and 4r.
Substituting the detected pressures Pa and Pb of lb and the constant p read from the memory 74 into the above equation (4fl'), calculate the head loss of the muddy water flowing inside the mud drainage pipe]8, and calculate the head loss of the muddy water flowing inside the mud drainage pipe]8, and calculate the head loss of the muddy water flowing inside the mud drainage pipe 8. The signal is output to the calculation unit 76.

The viscosity calculation unit 76 uses the data stored in the memory 74 and the pressure ml determiner 40a.

40b, head loss h, flow velocity V and density ρ of muddy water 100 measured in real time using a flow velocity/density detection device etc.
By substituting and into equations (+o) to (14) above, the viscosity coefficient μ of the muddy water 100 flowing in the υF mud main pipe 8 (as it is measured at a position close to the shield chamber 14,
4) is calculated in real time, and the calculated value is output to the viscosity control circuit 80.

The viscosity control circuit 80 compares the viscosity coefficient μ of the muddy water 00 measured in real time with a desired reference value to determine whether the viscosity coefficient μ of the muddy water 100 is appropriate.

Then, the rotation speed of the pump 64 of the viscosity control device 60 is controlled so that the measured viscosity of the muddy water [OC] is always at the optimum value, and a thickening agent, such as fine hentonite powder, is added to the muddy water]00. The amount of additives as the main component is controlled by one foot.

In this way, the viscosity of the muddy water supplied to the shield chamber 14 is automatically controlled in real time, and the viscosity of the muddy water 100 supplied to the shield chamber 14 is kept constant/controlled.
This can be controlled so that the viscosity is always optimal.

In particular, in this example, Shield Chan!・Since the viscosity of the muddy water]00 is measured near -14 and the thickening material is mixed and stirred, even if the viscosity of the muddy water]00 in the seal chamber 14 changes suddenly, this will not occur. Accurately track the value to a good value without time delay! ...can be controlled.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible within the scope of the invention.

For example, when measuring the viscosity of muddy water, it is necessary to measure and store the correlation between the differential pressure of muddy water and the viscosity of muddy water in advance, and use this correlation. You can go.

Figure 11 shows the correlation between the friction loss head determined in this way and the funnel viscosity F. As shown in the figure, the correlation between the two is almost linear, and the regression line is as follows: Passes the old calculated value for Shimizu. In this case, if d, l, and v change, it is expected that a corresponding straight line of f-αh+β will be formed.

Therefore, the funnel viscosity F can be determined by measuring the V friction loss head in the pipe and using the above correlation based on the measured friction loss head.

In addition, in the above embodiments, explanations have been made taking as an example the case where a thickener mainly composed of bentonite fine powder is used, but the present invention is not limited to this, but other stabilized liquids using thickener H 1) For example, it can also be applied to the case of measuring the viscosity of polymer-based stabilized liquids mainly composed of CMC water-soluble polymers (polymers).

Further, in the above embodiments, the viscosity measuring device is provided in the cane main pipe, but the present invention is not limited to this, and the device may be provided in the mud feeding pipe, for example, if necessary.

Further, in the apparatus of this embodiment, the viscosity control device 60 is provided in the mud feeding pipe 6, but the present invention is not limited to this. For example, the thickening material is directly supplied to the shield chamber 14. Alternatively, the muddy water treatment plant 30 may be configured to control the viscosity of the muddy water, although the responsiveness of the control will be reduced.

In addition, in this embodiment, the viscosity control device 60 attached to the mud feeding pipe 16 is used to control the viscosity of the muddy water 100. However, the present invention is not limited to this, for example, in a muddy water treatment plant. A certain amount of thickening agent is always mixed into the muddy water 100 supplied from the mud feeding pipe 6 through the mud feeding pipe 6.
muddy water using the viscosity control device 60 installed at 0]00
The thickening agent is added in response to minute fluctuations in viscosity.
It may also be configured to perform twitch control.

[Effects of the Invention] As explained above, according to the present invention, the viscosity of the muddy water supplied to the shield chamber can be precisely measured and feedback controlled so that the muddy water can function sufficiently as a stabilizing liquid. It's effective.

In particular, according to the present invention, by installing the pressure measuring means and the viscosity control means in a position relatively close to the seal channel, even if the viscosity of the muddy water in the seal channel fluctuates by 1%, this can be controlled. It becomes possible to accurately detect the viscosity without time delay and feedback control the viscosity to an appropriate value.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a preferred example of a seal excavator to which the present invention is applied, Fig. 2 is an overall explanatory diagram of the seal excavation method of this embodiment, and Figs. 3 (A) and (B) are , Fig. 4 is a characteristic diagram showing the relationship between the kinematic viscosity coefficient and the viscosity coefficient of the fluid, and Fig. 5 is an explanatory diagram showing the specific configuration of the pressure measuring device used in this embodiment. Flow velocity/density meter used in the example] An explanatory diagram showing an example of a meter; Figure 6 is an explanatory diagram of the waveform of ultrasonic waves transmitted and received toward muddy water; (B) is an explanatory diagram of the waveform of ultrasonic waves attenuated in muddy water. Figures 7 and 8 are examples of the correlation between muddy water density and ultrasonic attenuation rate. FIG. 9 is an explanatory diagram showing the relationship between Reynolds number and pipe friction coefficient, head loss and viscosity coefficient calculated using hydraulic formulas. FIG. FIG. 11 is an explanatory diagram showing the relationship between head loss and funnel viscosity F. FIG. 12 is an explanatory diagram showing an example of a conventional viscosity measuring device. 40a, 40b-pressure measuring device, 50... flow rate/density measuring device, 60 viscosity control device, 62... thickening tank supply device, 66...
... mixer, 70 viscosity calculation circuit, 80 ... viscosity control circuit. Agent Patent attorney Yuki Fu (and 2 others) Fig. 3 (A) (B) 42 flange 40 pressure J'J (see Fig. 4 and a half '1' main (SeC) Fig. 5□-/ A decay rate (dB/cm) Danpachi ← 1 Temporary Figure 12

Claims (3)

[Claims] (1) In a shield excavator that supplies muddy water to the shield chamber through a mud feeding pipe and discharges muddy water from the shield chamber through a mud draining pipe, the mud feeding pipe or the mud draining pipe is provided with a pressure measuring means for measuring the pressure of the muddy water flowing in the pipeline at at least two places; a viscosity calculating means for calculating the viscosity of the muddy water based on the pressure difference between the measured muddy water pressures; A viscosity control device for a shield excavator, comprising: viscosity control means for controlling the viscosity of mud water supplied to a shield chamber based on the viscosity of mud water supplied to a shield chamber. (2) In claim (1), the shield excavator is characterized in that the viscosity control means includes a thickener supply device that supplies a thickener that increases the viscosity of the muddy water to the mud pipe or the shield chamber. Mud water viscosity control device. (3) In claim (2), the viscosity control means includes a mixer installed directly on the mud feeding pipe or so as to bypass a part of the mud feeding pipe, and the viscosity control means includes a mixer installed in the mud feeding pipe directly or so as to bypass a part of the mud feeding pipe, and the thickening agent supplied from the thickening material supply device. A device for controlling the viscosity of muddy water in a shield excavator, which is characterized by stirring and mixing sticky material with muddy water.