JPH04102614A - Hardening method for poor subsoil by air force feeding - Google Patents

Abstract

PURPOSE:To facilitate cleaning for a short time by injecting the slurry of hardening agent in a cement series into poor subsoil during the period of time when poor subsoil is fed with pressure into a force feed pipe while being moved in a form of laminar flow, and subsequently in a form of wavy flow. CONSTITUTION:Poor subsoil which is kneaded by a screw conveyor 3 after it has been stored in a hopper 1, is loaded into a force feed tank 5. Loading is suspended at the time when the definite quantity of poor subsoil is loaded in the force feed tank 5. Compressed air is then fed into the force feed tank 5, so that poor subsoil within the force feed tank 5 is exhausted out of a force feed exhaust port 5a. On the other hand, a slurry supply pipe 13 is communicated with a feed pipe close to the down stream side of a force feed valve 9a, the slurry of hardening agent is pressurized by a pressure pump 11, much higher than pressure within a force deed pipe 9, so that the specified quantity of the slurry of hardening agent is thereby injected uniformly and continuously over the upper surface of poor subsoil flowing in a form of laminar flow within the period of time when poor subsoil is exhausted. Since then, poor subsoil is sufficiently mixed with the slurry of hardening agent during the period of time when it flows in a form of wavy flow in particular, it is throughly hardened at an early stage after it is delivered to its destination.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to dredging soft soil such as sludge and sand deposited on the bottom of blocked sea areas, rivers, lakes, dams, etc. This article relates to a method for rapidly solidifying solidified materials by pressure-feeding them to a location (hereinafter referred to as the destination).

[Conventional technology]

Conventionally, in order to transport dredged soft soil to its destination, the dredged soft soil is loaded onto a special transport vessel using excavation equipment such as a backhoe or grab bucket mounted on a barge, transported to a quay, and then temporarily stored and stored. This was then transferred to a truck or dump truck and transported to its destination.

However, according to this method, transshipment, etc. is time-consuming, and problems such as so-called dump truck pollution and the construction of construction roads occur during land transportation.

For this reason, recently, in addition to the excavation equipment, a pressure-feeding tank, a pressure-feeding device mainly consisting of an air compressor, and the necessary auxiliary equipment have been installed on a barge floating on the water surface to remove stone blocks, etc. from the dredged soft soil. Adds fluidity to the soft soil that has been mixed after removal,
This is put into a pressure tank, and compressed air is used to send it through a pressure pipe connected to the water surface or on land to the destination.
A dredging pressure system has been developed and implemented in which water is discharged from a discharge port at the tip of a pressure pipe at the destination.

According to this dredging and pumping system, dredged soft soil can be transported efficiently without the trouble of transferring soft soil or problems such as dump pollution.
(Can be pumped up to 000m).

The transported soft soil needs to be solidified at the destination depending on the purpose of use at this destination, but if it is particularly necessary to solidify it early, the soft soil may need to be solidified with a cement-based solidifying agent (
A solidifying agent (hereinafter referred to as a solidifying agent) is added and stirred and mixed to solidify.

However, in the past, the solidification agent was added and mixed manually or by using solidification processing equipment for each small area, which required a large number of personnel and equipment.

For this reason, the present inventor has developed a method that can quickly and efficiently solidify the soft soil pumped by a dredging pumping system according to the purpose.
No. 65 (see Japanese Unexamined Patent Publication No. 1262999).

In other words, this method injects a solidification agent slurry into the soft soil that is being put into a pressure transfer tank, and by continuously pumping the soft soil to which the solidification agent has been added in the form of a slurry to the destination, it is possible to achieve high efficiency. Moreover, it is an extremely rational method that can effectively solidify at an early stage.

[Problem to be solved by the invention]

However, although the above-mentioned solidification method is extremely effective, if the pumping of soft soil is interrupted for a long time (for example, when you take a break from work until the next morning after finishing the day's work), the solidification method may cause damage inside the pumping tank and pipes. The remaining soft soil will harden and interfere with the next work, so it is necessary to flush the inside of the pressure feed tank and pressure feed pipe with water to drain and remove the soft soil containing the solidifying agent.

In this case, the pressure feed pipe has a smooth inner surface and no protrusions, so it is easy to wash with water, but inside the pressure feed tank, multiple blades are attached to the rotating shaft to mix the soft soil and solidification agent slurry. Since the internal structure is complicated, cleaning the inside of the pressure-feeding tank, such as removing soft soil adhering to the blades and rotating shaft, is extremely difficult and requires a lot of effort.

The present invention solves the above-mentioned conventional problems, and when interrupting the work of pumping soft soil to which a solidifying agent has been added, cleaning the pumping tank, pipes, etc. by washing with water can be done easily in a short time without much effort. It is an object of the present invention to provide a method for solidifying soft soil by pneumatic pumping, which can achieve the same effect as the conventional method for solidifying soft soil that has been pumped.

[Means to solve the problem]

The present invention was made as a result of various studies in order to achieve the above object, and includes a step of charging dredged soft soil into a pressure feeding tank, and a process in which the soft soil charged into the pressure feeding tank is conveyed by compressed air through a pressure feeding pipe. In the dredging and pressure feeding system for soft soil, which comprises a step of pumping the soil to a location and solidifying it, when the soft soil discharged from the pumping tank is pumped through the pumping pipe, a laminar flow followed by a wavy flow is formed. While flowing,
This method is characterized by injecting a cement-based solidifying agent slurry into the soft soil.

[Effect]

Observation of the flow of soft soil being pumped through the pressure pipe
(This was done by observing the flow of soft soil inside the plastic pipe from the side).The soft soil does not flow over the entire length of the pipe, filling the cross-sectional area, but instead flows into the pressure tank. For a certain distance (approximately 20 to 30 m) from the vicinity where the water is discharged into the pressure pipe, there is a space above the pressure pipe, and the upper surface of the flow does not have much ups and downs, and flows continuously in a relatively calm state. It flows in a so-called laminar flow,
After that, although a space remains above the pressure-feeding pipe, the upper surface of the flow continues as a so-called wavy flow in a wavy state. And the distance N (approximately 2
After flowing (from 0 to 30 m), the flow becomes a plug flow in which the soft soil fills the cross-sectional area of the pressure pipe and flows intermittently with air, and from the discharge port, the soft soil and air flow in this state. was observed to be discharged in an alternating and intermittent manner.

Therefore, the present invention has been made by focusing on utilizing the above phenomenon. That is, the present invention injects a solidification agent in the form of a slurry between a laminar flow and a wavy flow following the second laminar flow in the flow of soft soil being pumped through a pressure pipe. Due to the existence of the upper space, the solidifying agent slurry can be poured evenly onto the flowing soft soil, and further, while the soft soil is flowing, especially while the top surface is waving in a wavy flow, the solidifying agent slurry can be poured evenly onto the flowing soft soil. and soft soil are mixed well. Therefore, at the destination, it can solidify quickly and exhibit sufficient strength.

In addition, since the solidifying agent slurry is injected into the pressure-feeding pipe beyond the pressure-feeding tank, cleaning at the time of interruption due to the completion of pressure-feeding work is extremely easy and quick by washing only the pressure-feeding pipe with water, regardless of the pressure-feeding tank. It is something that can be done on time.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, 1 is a hopper, which is equipped with a vibrating screen 2 above and a screw conveyor 3 below. 4 is a grab bucket that carries the dredged soft soil above the hopper 1, then opens the grab and drops it onto the vibrating screen 2. The dropped soft soil is transferred to hopper 1 after large solids are removed by vibrating screen 2.
It falls inside and is stored, and is transferred to the lower screw conveyor 3.
The mixture is kneaded, given a certain degree of fluidity, and then introduced into a pressure tank 5 installed below via a connecting pipe 6. A rotary shaft 7 having a plurality of blades 7a is installed in the lower part of the pressure-feeding tank 5 to knead the soft soil introduced from the screw conveyor 3 through the connecting pipe 6, and further improve its fluidity. Do well.

Further, an air pipe 8 for supplying compressed air is connected to the upper side of the pressure feeding tank 5 through a pressurizing valve 8a.
Furthermore, a butterfly valve 6a is provided in the middle of the connecting pipe 6.

Reference numeral 9 denotes a pressure feed pipe, which communicates with the pressure feed outlet 5a at the bottom of the pressure feed tank 5 through a pressure feed valve 9a, and is supported by a float floating on the water surface or a column erected in the water, and extends to land; It is further extended to the destination, and the discharge port at the tip is opened at the destination.

Reference numeral 10 denotes a supply pipe for pressurized compressed air, which opens toward the longitudinal axis of the pressurized pipe 9 in the vicinity of the pressurized discharge port 5a of the pressurized tank 5 with a pressurized air valve 10a interposed therebetween.

Reference numeral 11 denotes a slurry tank, in which, for example, a solidifying agent slurry produced by mixing a predetermined amount of solidifying agent and water in a land-based solidifying agent slurry production plant (not shown) is fed to a hose 1.
2. After being transported, it is stored for an hour. Note that, if necessary, a stirring device such as a rotary blade is provided inside to prevent solidification.

The slurry tank 11 and the vicinity of the downstream side of the pressure feed valve 9a of the pressure feed pipe 9 are communicated through a slurry supply pipe 13, and a pressure pump 14 and a slurry injection valve 13a are provided in the middle.

The above-mentioned parts, such as the hopper 1, the screw conveyor 3, the pressure tank 5, and the slurry tank 11, are all installed directly on a barge (not shown) floating on the water or via a machine frame, etc. Further, rotating parts such as the screw conveyor 3 and the rotating shaft 1O are driven by a drive device such as a motor speed reduction device, which is not particularly designated by a reference numeral.

Hereinafter, a method of pumping dredged soft soil to a target and solidifying it using the apparatus configured as described above will be explained.

When putting the soft soil stored in the hopper 1 and mixed by the screw conveyor 3 into the pressure feeding tank 5, except for opening the butterfly valve 6a in the connecting pipe 6, all other valves 8a, 9a, 10a and 13a are closed.

When a certain amount (approximately 273 of the internal capacity) of soft soil is charged into the pressure feeding tank 5, the butterfly valve 6a is closed to stop the feeding. Note that the rotating shaft 7 in the pressure-feeding tank 5 starts rotating before the start of charging, and continues to rotate for a necessary time even after stopping the charging to provide sufficient fluidity.

Next, the pressure feed valve 9a in the pressure feed pipe 9 is opened, and the pressure valve 8a in the air pipe 8 is opened, and the compressed air (for example, 7
kg/cm'') into the pressure-feeding tank 5, and the soft soil in the pressure-feeding tank 5 is discharged from the pressure-feeding outlet 5a, and at the same time, the pressure-feeding air valve 10a is opened to open the supply pipe 10.
Pressurized air is supplied into the pressure feeding pipe 9, and the pressure feeding of the soft soil by the pressure feeding pipe 9 is started.

As described above, the soft soil flowing through the pressure-feeding pipe 9 due to this pressure-feeding is approximately 2
After flowing as a laminar flow A for 0 m, the flow changes to a wavy flow B, and further becomes a plug flow C, which is forced to the discharge port and discharged.

However, in this embodiment, the slurry supply pipe 13 is communicated near the downstream side of the pressure feed valve 9a, and the solidifying agent slurry is pressurized by the pressure pump 14 to a higher pressure than the pressure inside the pressure feed pipe 9, and the slurry is injected. By opening the valve 13a, a specified amount of the solidifying agent slurry was continuously and evenly injected onto the upper surface of the flowing soft soil in a laminar flow within the time that the soft soil was being discharged.

The soft soil into which the solidifying agent slurry has been injected must be sufficiently mixed with the solidifying agent slurry while flowing, especially during the flow in a wavy flow, and be quickly and sufficiently solidified after being discharged at the destination. was completed.

That is, a total of 80,000 m'' of reclamation work was carried out using the above method, and all of the reclamation work was solidified in two days to a strength sufficient to allow construction machinery such as bulldozers to run on it.

In addition, each of the above-mentioned valves 6a, 8a, 9a, 10a, 1
Opening/closing 3a or operating/stopping the pressurizing pump 14, etc.
By controlling all of them electrically, they can operate automatically in conjunction with each other.

Further, in the above embodiment, an example was described in which one pressure-feeding tank 5 was installed, but by installing a plurality of tanks and operating them alternately, it is possible to continuously perform pressure-feeding of soft soil.

Furthermore, in the above embodiment, the slurry supply pipe 13 is connected to the vicinity of the downstream side of the pressure-feeding valve 13a, but it may also be connected to the vicinity of the boundary between the laminar flow and the wavy flow a little further downstream, or within the wavy flow. It is effective. However, it is preferable to inject the solidifying agent slurry preferably in laminar flow.

Next, the amount of solidifying agent (generally available on the market) to be added is determined by the nature of the soft soil, water content ratio, purpose of use of the destination, number of solidification days, etc., but in order to obtain high strength, it is generally necessary to increase the water content ratio. If the softness is large, a large amount of solidifying agent must be added.

〔Effect of the invention〕

As described above, in the present invention, the solidifying agent slurry is injected while the soft soil being pumped through the pumping pipe flows in a laminar flow followed by a wavy flow. It mixes well with the agent slurry, solidifies quickly at the destination where it is pumped, and exhibits sufficient strength.
Since there is no soft soil containing a solidification agent in the pressure tank when the pressure feeding operation is interrupted, there is no need to clean the inside of the pressure tank very carefully. Since it is smooth, cleaning the pressure tank and the pressure pipe when the pressure feeding operation is interrupted does not require much effort, and can be easily and quickly cleaned.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention. 1: Hopper, 2: Vibrating screen, 3 Nigelabu conveyor, 4 Nigelab packet, 5: Pressure feeding tank, 6:
Connecting pipe, 6a: Butterfly valve, 7: Rotating shaft, 7a: Vane, 8: Air piping, 8a: Pressurizing valve, 9: Pressure feeding pipe, 9a: Pressure feeding valve, 11 Nislary tank, 13 Nisslary supply pipe,
13a Nislary injection valve, 14: Pressure pump.

Claims (1)

[Claims] In a dredging and pressure-feeding system for soft soil, comprising a step of charging dredged soft soil into a pressure-feeding tank, and a step of pumping the soft soil charged into the pressure-feeding tank with compressed air to another location via a pressure-feeding pipe and solidifying it. When the soft soil discharged from the pressure feeding tank is pumped through the pressure feeding pipe, a cement-based solidifying agent slurry is injected into the soft soil while flowing in a laminar flow followed by a wavy flow. A method of solidifying soft soil using air pressure.