JP2023021209A - Cyclone device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cyclone device that separates sand contained in a stabilization solution for efficiently measuring a percentage of sand contained in the stabilization solution for evaluation.

SOLUTION: An evaluating device 20 comprises a first specific gravity measuring part 21, a second specific gravity measuring part 22, and a control part 31. The first specific gravity measuring part 21 measures a first measurement value which is a specific gravity of a stabilization solution supplied to a cyclone device 25 which removes sand contained in the stabilization solution. The second specific gravity measuring part 22 measures a second measurement value which is a specific gravity of the stabilization solution having the sand ejected from the cyclone device 25 removed therefrom. The control part 31 calculates a percentage of sand in the stabilization solution, from a value based on a result of comparison between the first measurement value and the second measurement value.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a cyclone device for separating sand contained in a stabilizing liquid used in the construction of cast-in-place concrete piles and diaphragm walls.

A stabilizing liquid (bentonite mud) is used to prevent collapse of the wall of the drilled hole. Since the properties of the stabilizing liquid may affect the quality of the pile concrete built in the hole, the properties of the stabilizing liquid are measured. Generally, the viscosity, specific gravity and sand content of the stable liquid are measured using a funnel viscometer, mud balance and sand content meter respectively. Furthermore, there is also a technique for periodically measuring properties of a stable liquid (see, for example, Patent Document 1). In the method for measuring properties of muddy water described in this document, the specific gravity, viscosity and sand content of the stable liquid are measured. In this case, the sand content is determined by classifying the sand contained in the muddy water discharged from the muddy water measuring container and measuring the weight of the classified sand.

JP-A-8-35924

However, it takes time and effort to measure the properties of the stable liquid such as the sand content.

A cyclone device that solves the above problems is a cyclone device that separates sand contained in a stabilizing liquid, wherein a supply pipe through which the stabilizing liquid filled inside the hole is connected is connected, and through the supply pipe, The sand separated from the supplied stabilizing liquid is discharged from below, and the stabilizing liquid from which the sand is separated and removed is discharged through the discharge pipe connected to the upper part, and the stabilizing liquid to be removed is discharged. The peripheral speed and the inflow speed of the stabilizing liquid are adjusted according to the diameter of the sand particles and the viscosity of the stabilizing liquid.

ADVANTAGE OF THE INVENTION According to this invention, the sand content rate of a stable liquid can be measured efficiently and the property of a stable liquid can be evaluated.

Explanatory drawing explaining the system configuration|structure of the evaluation apparatus in embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing explaining the specific gravity difference in embodiment, Comprising: (a) shows the sand content meter currently used, (b) is explanatory drawing explaining the relationship between air, water, and a soil particle. FIG. 4 is an explanatory diagram for explaining the relationship between the sand content and the equivalent sand content according to the conventional method in the embodiment, where (a) is a measured value of each stable liquid and (b) is a graph showing the numerical value of (a).

An embodiment of a cyclone device will be described below with reference to FIGS. 1 to 3. FIG. Here, properties such as the sand content of the stable liquid discharged from the pile hole and collected are measured and evaluated.

As shown in FIG. 1 , the inside of the excavated pile hole 10 is filled with a stabilizing liquid 11 . A pump 15 is arranged at the bottom of the pile hole 10 . A recovery pipe 16 is connected to the pump 15 . The pump 15 is driven to discharge the stabilizing liquid 11 from the recovery pipe 16 to the outside of the pile hole 10 . Recovery pipe 16 is connected to plant 17 . The plant 17 comprises a plurality of water tanks for settling and removing sand from the stabilizing liquid. Then, the plant 17 causes sand in the recovered stable liquid to settle in each water tank, and supplies a good stable liquid from which the sand is removed to the pile hole 10 . This replaces the stabilizing liquid in the stake hole 10 with a good stabilizing liquid.

A supply pipe 18 is branched and connected to the recovery pipe 16 via a valve (not shown). This supply pipe 18 is connected to the evaluation device 20 and supplies part of the stabilizing liquid flowing through the recovery pipe 16 to the evaluation device 20 . Here, the supply pipe 18 is supplied with an amount of about 1/5 to 1/30 of the stabilizing liquid with respect to the flow rate flowing through the recovery pipe 16 . In this embodiment, the amount of the stable liquid flowing through the supply pipe 18 is set to about 1/15 of the amount of the stable liquid flowing through the recovery pipe 16 .

The evaluation device 20 includes a first specific gravity measuring section 21 , a second specific gravity measuring section 22 , a mud tank 23 , a cyclone device 25 and a viscosity measuring section 26 . The stable liquids supplied to the first specific gravity measuring unit 21 , the second specific gravity measuring unit 22 and the viscosity measuring unit 26 are accumulated in the mud tank 23 and then supplied to the plant 17 .

In the evaluation device 20, the supply pipe 18 is connected to a cyclone device 25 as a sand removing device. Further, a branch pipe of the supply pipe 18 is connected to the first specific gravity measuring section 21 via a valve 21v. The first specific gravity measuring unit 21 measures the specific gravity (first measured value) of the stable liquid flowing through the supply pipe 18 . The first specific gravity measuring unit 21 includes a cylindrical container 21c with an open upper surface and a constant capacity, and a pressure gauge 21a for measuring the weight of the stable liquid in the container 21c.

A branch pipe is connected to the lower end of the container 21c, and the stabilizing liquid is supplied to the container 21c from below. By this supply, the stabilizing liquid inside the container 21c flows upward and overflows from the upper opening of the container 21c. Further, below the container 21c of the first specific gravity measuring unit 21, a drain pipe 21d is provided via a valve for discharging the stable liquid inside the container 21c as required.

The pressure gauge 21a is mounted at a position (mounting position) a predetermined distance (for example, 1 m) below the upper surface of the container 21c. The pressure gauge 21a measures the weight (pressure) of the stable liquid in the container 21c above the mounting position, and transmits the measured value to the management unit 30 as the specific gravity of the stable liquid.

A branch pipe of the supply pipe 18 is connected to the viscosity measuring section 26 . This viscosity measuring unit 26 measures the viscosity of the stable liquid flowing through the supply pipe 18 . In this embodiment, a vibrating viscometer is used as the viscosity measuring unit 26 .

A cyclone device 25 connected to the supply pipe 18 is a centrifugal separator that separates sand (soil particles having a particle size of 0.075 mm or more) contained in the stable liquid. The cyclone device 25 discharges sand separated from the stable liquid flowing through the supply pipe 18 from below. The cyclone device 25 also discharges the stable liquid from which the sand is separated to the mud tank 23 through the discharge pipe 28 connected to the upper part. Details of the cyclone device 25 will be described later.

A branch pipe of the discharge pipe 28 is connected to the second specific gravity measuring section 22 via a valve. The second specific gravity measuring section 22 measures the specific gravity of the stable liquid flowing through the discharge pipe 28 . Here, the second specific gravity measuring section 22 has the same configuration as the first specific gravity measuring section 21 . The second specific gravity measuring unit 22 also includes a cylindrical container 22c having a constant capacity and a pressure gauge 22a for measuring the weight (pressure) of the stable liquid in the container 22c. Furthermore, below the container 22c of the second specific gravity measuring unit 22, a drain pipe 22d is provided via a valve.

Furthermore, the evaluation device 20 comprises a management unit 30 . The management unit 30 is connected to the first specific gravity measuring section 21, the second specific gravity measuring section 22, and the viscosity measuring section 26, and acquires the measured values measured by these.

The management unit 30 has a control section 31 and a display section 32 .
The control unit 31 calculates the sand content rate contained in the stable liquid. The sand content is the volumetric ratio of sand present in the muddy water (stabilized liquid). The control unit 31 acquires the specific gravity (first measured value) measured by the first specific gravity measuring unit 21 and the specific gravity (second measured value) measured by the second specific gravity measuring unit 22 . Then, the control unit 31 calculates the sand content rate using the first measured value, the second measured value, and a pre-stored sand content calculation formula (formula (2) described later). Details of the calculation of the sand content will be described later. Then, the control unit 31 stores the calculated sand content, the measured specific gravity of the stable liquid (first measured value), and the viscosity acquired from the viscosity measuring unit 26 in the memory.

Furthermore, the management unit 30 controls the opening and closing of the valves 21v and 22v of the first specific gravity measuring section 21 and the second specific gravity measuring section 22 and the valves of the drain pipes 21d and 22d.
The display unit 32 is a display that displays the specific gravity, viscosity, and sand content of the stable liquid.

<Cyclone device 25>
Next, details of the cyclone device 25 for removing sand will be described.
Here, in order to separate the sand, the sedimentation velocity of sand calculated from the effective diameter of the cyclone device 25 and the retention time of the stable liquid in the cyclone device 25 is considered.
The sedimentation velocity (V) of sand in the cyclone device 25 is expressed by the Stokes equation (equation (1) below).
V= ⁽ ρs-ρw) ^gD2 /18μ=(ρs-ρw) ^Vt2D2 /18μr (1)

where ρs is sand density (2.65×10 ³ kg/m ³ ), ρw is water density (1.00×10 ³ kg/m ³ ), g is gravitational acceleration (9.807 m/s ² ), μ is muddy water is the viscosity (Pa·s), D is the diameter of the sand particle (m), r is the radius of the centrifugal field (m), and Vt is the circumferential velocity (m/s).
As shown in the above formula (1), the sedimentation speed of sand is affected by the diameter, peripheral speed and viscosity of sand particles to be removed.

The grain size of sand is 0.075 mm to 2 mm. In the present embodiment, the cyclone device 25 is set so as to be able to remove the particle size of sand contained in the stabilizing liquid, taking into consideration the properties of earth and sand generated at the actual site. Also, during the work of replacing the stabilizing liquid in the pile hole 10, the peripheral speed of the cyclone device 25 is adjusted in consideration of the variation in the viscosity of the stabilizing liquid. Since this peripheral velocity is determined by the diameter (shape) of the cyclone device 25 and the flow velocity of the cyclone device 25, it is adjusted by the velocity (inflow velocity) of the stable liquid. If the viscosity of the muddy water is expected to further increase, the peripheral speed of the cyclone device 25 is further increased.

<Method for calculating sand content>
Next, a method for calculating the sand content ratio executed by the control unit 31 will be described with reference to FIGS. 2 and 3. FIG. Here, the sand content (%) calculated using the calculation method of the present embodiment is referred to as equivalent sand content.
The control unit 31 of this embodiment calculates the equivalent sand content x (%) by the following equation (2).
x = 140 x (ρi - ρf) / (2.65 - ρf) (2)
Here, ρi and ρf are the specific gravity of the stable liquid before passing through the cyclone device 25 (first measured value) and the specific gravity of the stable liquid after passing through (second measured value), respectively. The equivalent sand content is calculated from the difference in specific gravity and the difference in loss of sand content, assuming that the difference in specific gravity is mainly due to sand content.

Specifically, referring to FIG. 2(a), a conventional sand content measurement method using a sand meter 50 will be described. The sand meter 50 uses 100 mL of stabilizing liquid in it. The sand meter 50 removes particles of 75 μm or less in this with a sieve and washes them with water, and measures the lamination volume of the sand (soil particles of 75 μm or more) remaining in the water 51 to determine the sand fraction. get. For example, a sand content of 5% means that 100 mL of the stable liquid contained in the sand meter 50 contains 5 mL of sand.

The mass difference due to the difference in specific gravity before and after passing through the cyclone device 25 per 100 mL of the stable liquid is shown as follows.
Mass difference due to specific gravity difference = 100 x (ρi - ρf) (3)

Here, as shown in the configuration diagram of soil (sand) in FIG. Let V be the total volume of water and soil particles.
The difference in mass due to the loss of sand before and after passing through the cyclone device 25 is expressed by n (=Vv/V×100) as the porosity of the sand 52 in the portion where the sand accumulates in the sand meter 50, and as the density of the sand. ρs (=2.65 g/cm ³ ) is shown as follows.
Mass difference due to sand loss = (ρs - ρf) x x x (1 - n/100) (4)

Since the difference in mass due to specific gravity before and after passing through the cyclone device 25 is (generally) equal to the difference in mass due to loss of sand content, the following equation is obtained from equations (3) and (4) above.
100×(ρi−ρf)=(ρs−ρf)×x×(1−n/100)…(5)

The following equation is obtained by transforming this equation (5) with respect to the equivalent sand content x.
x=100(ρi-ρf)/((ρs-ρf)×(1-n/100))…(6)

Here, the value of the equivalent sand content x is expressed by the following equation, where α is a coefficient that takes into consideration the characteristics of the evaluation device 20 and the void ratio of the sand 52 . This coefficient α can be set individually for each usage condition of the evaluation device 20 .
x=α×(ρi−ρf)/(ρs−ρf)
This time, from the correlation of the measured values at the time of the experiment, α = 140 and the specific gravity of sand is 2.65, and converted by the following formula.
x = 140 x (ρi - ρf) / (2.65 - ρf)

<Relationship between sand content and equivalent sand content according to the conventional method>
FIG. 3(a) shows the sand content measured by the sand meter 50 (according to the conventional method) and the equivalent sand content of the present invention for stable liquids having different properties. Further, FIG. 3(b) shows a graph in which the value of the sand content by the conventional method is plotted on the horizontal axis and the converted sand content is plotted on the vertical axis. According to this, the sand content ratio and the equivalent sand content obtained by the conventional method almost correspond to each other, indicating that the equivalent sand content has almost the same accuracy as the conventional method.

<Measurement processing of the evaluation device 20>
Next, measurement processing in the evaluation device 20 shown in FIG. 1 will be described.
First, the pump 15 arranged in the pile hole 10 is driven to discharge the stable liquid in the pile hole 10 to the plant 17 through the recovery pipe 16 . Furthermore, in the plant 17 a conditioned stabilizing liquid is supplied to the pile hole 10 .

Here, part of the stabilizing liquid in the recovery pipe 16 is supplied to the cyclone device 25 of the evaluation device 20 via the supply pipe 18 . In this case, since the valve 21v is open, the stable liquid is supplied from the supply pipe 18 to the first specific gravity measuring section 21 . In the present embodiment, adjustment is made so that a portion (for example, 30% or less) of the flow rate of the stabilizing liquid flowing through the evaluation device 20 flows to the first specific gravity measuring section 21 . This stabilizing liquid is supplied from the bottom of the container 21c of the first specific gravity measuring unit 21, and causes the stabilizing liquid in the container 21c to flow upward and overflow the container 21c. The pressure gauge 21a of the first specific gravity measuring unit 21 periodically (for example, every 5 seconds) measures the pressure (specific gravity) of the stable liquid in the container 21c. The pressure gauge 21 a transmits the measured value (first measured value) of the stable liquid to the management unit 30 .

Furthermore, the stabilizing liquid is supplied to the viscosity measuring section 26 via the branch pipe of the supply pipe 18 . The viscosity measurement unit 26 measures the viscosity of the stable liquid periodically (for example, every 5 seconds) and transmits the measured value (viscosity) to the management unit 30 .

Also, the stable liquid from which sand has been removed by the cyclone device 25 is discharged to the mud tank 23 through the discharge pipe 28 . In this case, the valve 22 v is opened to supply the stable liquid in the discharge pipe 28 to the second specific gravity measuring section 22 . In the present embodiment, adjustment is made so that the stable liquid flows to the second specific gravity measuring section 22 at substantially the same flow rate as the first specific gravity measuring section 21 . Since this stabilizing liquid is gradually supplied from below the container 22c of the second specific gravity measuring unit 22, the stabilizing liquid in the container 22c slowly flows upward and overflows from the top of the container 22c. The pressure gauge 22a of the second specific gravity measuring unit 22 periodically (for example, every 5 seconds) measures the pressure (specific gravity) of the stable liquid in the container 22c, and measures the measured value of the stable liquid (second measured value). to the management unit 30 .

The control unit 31 of the management unit 30 calculates the sand content rate using the obtained first measured value and second measured value and the sand content calculation formula. The control unit 31 associates the calculated sand content with the specific gravity (first measured value) and viscosity of the stable liquid obtained at the same time, and stores them in the built-in memory. Then, the control section 31 of the management unit 30 displays information (sand fraction, specific gravity and viscosity) on the stable liquid on the display section 32 . The administrator monitors the measured values (such as the sand content of the stable liquid) displayed on the display unit 32 .

Also, the management unit 30 periodically (for example, every 30 minutes) closes the valves 21v and 22v and opens the valves of the drain pipes 21d and 22d. As a result, the stable liquid in the containers 21c, 22c is discharged from the lower ends of the containers (21c, 22c) of the first and second specific gravity measuring units (21, 22). After a predetermined time (for example, several seconds) has passed, the valves of the drain pipes 21d and 22d are closed, the valves 21v and 22v are opened, and the containers (21c and 22c) of the first and second specific gravity measuring units (21 and 22) are After filling with the stabilizing liquid, the specific gravity of the stabilizing liquid is measured again. As a result, the evaluation device 20 is calibrated at regular time intervals.

<Specific example>
Here, the sand content of the recovered liquid will be explained.
For example, assume that the measured value (first measured value) of the first specific gravity measuring unit 21 and the measured value (second measured value) of the second specific gravity measuring unit 22 are the values shown in Table 1 below. In this case, the converted sand content is equal to or higher than the judgment value (1.0%), so the work of replacing the stabilizing solution is continued. Then, when the converted sand content becomes smaller than the judgment value, the replacement work of the stabilizing liquid is stopped.

According to this embodiment, the following effects can be obtained.
(1) In the present embodiment, an expression including the specific gravity (first measured value) of the stable liquid supplied to the cyclone device 25 and the specific gravity (second measured value) of the stable liquid from which sand has been removed in the cyclone device 25 , the sand content of the stable solution is calculated. Thereby, the sand content of the stable liquid can be efficiently measured.

(2) In the present embodiment, part of the stable liquid recovered from the pile hole 10 to the plant 17 is flowed into the evaluation device 20, and the evaluation device 20 evaluates the properties of the stable liquid. Thereby, the properties of the stable liquid flowing from the pile hole 10 to the plant 17 can be efficiently evaluated.

(3) In the present embodiment, a branch pipe of the supply pipe 18 is connected to the lower ends of the containers (21c, 22c) of the first and second specific gravity measuring units (21, 22). As a result, the stabilizing liquid is supplied to the containers 21c and 22c from below and flows upward. The specific gravity of the flowing stable liquid can be continuously and efficiently measured without causing Furthermore, the stable liquid flows in several seconds from the supply pipe 18 to which the first specific gravity measuring section 21 is connected to the discharge pipe 28 to which the second specific gravity measuring section 22 is connected. As a result, the first specific gravity measuring unit 21 and the second specific gravity measuring unit 22 can measure the specific gravity of almost the same stable liquid almost simultaneously with almost no delay.

(4) The first and second specific gravity measuring units (21, 22) of the present embodiment are provided with pressure gauges 21a, 22a provided at positions 1 m from the opened upper end of the container (21c, 22c). As a result, the pressure gauges 21a and 22a measure the pressure inside the containers 21c and 22c, so that the specific gravities of the stable liquids inside the containers 21c and 22c can be efficiently measured.

(5) In the present embodiment, the control section 31 of the management unit 30 displays the measured values of the specific gravity, viscosity, and sand content of the stable liquid measured at the same time on the display section 32 . Thereby, a plurality of properties required for property management of the stable liquid can be grasped at the same time.

(6) In this embodiment, the control section 31 of the management unit 30 periodically opens the valves of the drain pipes 21d and 22d of the first specific gravity measuring section 21 and the second specific gravity measuring section 22 . Thereby, the calibration of the evaluation device 20 can be performed at regular time intervals.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
In the above embodiment, the specific gravity difference obtained by subtracting (subtracting) the second measured value measured by the second specific gravity measuring unit 22 from the first measured value measured by the first specific gravity measuring unit 21 is calculated from the specific gravity of sand (2.65). The sand content was calculated by dividing the second measured value by the subtracted specific gravity difference and multiplying by a factor (140). The sand content of the stable liquid is not limited to this coefficient (140) or the calculation method. For example, the value obtained by dividing the first measured value by the second measured value is used to calculate the sand content using the corresponding conversion table. It is sufficient if the sand content can be measured using the result of comparison between the first measured value and the second measured value. Furthermore, it may be calculated by adjusting the sand content according to the measured viscosity. Specifically, the value obtained by comparing the first measured value and the second measured value is corrected using a correction value corresponding to the measured viscosity value, and the sand content is calculated according to this correction value.

- In the above embodiment, the controller 31 of the management unit 30 displays the calculated sand content, the measured specific gravity, and the viscosity on the display 32 . In addition to this, the control unit 31 may determine whether or not the calculated sand content exceeds the reference value, and indicate the determination result. Furthermore, the management unit 30 may manage information other than the sand content, specific gravity, and viscosity, such as the pH of the stable liquid and the amount of filtered water, which are information related to the properties of the stable liquid. Furthermore, a communication section may be provided in the management unit 30 to transmit the sand content, specific gravity and viscosity to the terminal of the manager.

- In the above embodiment, the administrator monitors the sand content displayed on the display section 32 of the management unit 30 . Alternatively, the control section 31 of the management unit 30 may automatically stop the recovery and supply of the stabilizing liquid when the sand content ratio becomes equal to or less than the criterion value. In this case, the recovery pipe 16 and the supply pipe are provided with valves. Then, when the sand content ratio becomes equal to or less than the judgment reference value, the control unit 31 outputs an instruction signal to close these valves to control the supply and recovery of the stable liquid.

- In the above-described embodiment, the collected liquid flowing from the pile hole 10 to the plant 17 was evaluated. The stable liquid to be evaluated is not limited to the recovered liquid recovered from the pile hole 10 and may be the feed liquid supplied to the pile hole 10 . In this case, the evaluation device 20 is attached to the pipeline that supplies the stabilizing liquid from the plant 17 to the pile hole 10 via a supply pipe. For example, as shown in Table 2 below, when the sand content in the stabilizing liquid to be supplied is equal to or lower than a reference value (for example, 1.0%), the stabilizing liquid is continued to be supplied.

An alarm may be displayed on the display unit 32 when the sand content rate contained in the supplied stabilizing liquid is equal to or higher than a reference value (for example, 1.0%). Furthermore, this alarm may be sent to the administrator's terminal.
Furthermore, the evaluation device 20 may be provided in each of the pipeline for the recovered liquid flowing from the pile hole 10 to the plant 17 and the pipeline for the feed liquid supplied from the plant 17 to the pile hole 10 .

- In the above embodiment, the stable liquid supplied to the evaluation device 20 through the supply pipe 18 is temporarily accumulated in the mud tank 23 and then returned to the plant 17 . Instead of temporarily accumulating the stable liquid in the mud tank 23, the stable liquid supplied to the evaluation device 20 may be returned to the downstream side of the pipe line (recovery pipe 18 in the above embodiment) connected to the supply pipe 18. good.
- In the above embodiment, the cyclone device 25 is used as the sand removal device. The device is not limited to the cyclone device 25 as long as it can remove sand.

DESCRIPTION OF SYMBOLS 10... Pile hole, 11... Stabilizing liquid, 15... Pump, 16... Recovery pipe, 17... Plant, 18... Measurement supply pipe, 20... Evaluation device, 21... First specific gravity measuring unit, 21a, 22a... Pressure gauge, 21c , 22c... container, 21d, 22d... drain pipe, 21v, 22v... valve, 22... second specific gravity measuring unit, 23... mud tank for measurement, 25... cyclone device, 26... viscosity measuring unit, 28... discharge pipe, 30 ... property management unit, 31 ... control unit, 32 ... display unit, 50 ... sand content meter, 51 ... water, 52 ... sand.

Claims (1)

A cyclone device for separating sand contained in a stabilizing liquid,
A supply pipe through which the stabilizing liquid filled inside the hole flows is connected,
discharging sand separated from the stable liquid supplied through the supply pipe from below;
Discharge the stable solution from which the sand is separated and removed through the discharge pipe connected to the upper part,
A cyclone device characterized by adjusting a peripheral speed and an inflow speed of the stabilizing liquid according to the diameter of sand particles to be removed in the stabilizing liquid and the viscosity of the stabilizing liquid.

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