JPH0548332B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> This invention relates to a recovery stem for high viscosity mud water in a mud water excavation method.

<<Background of the invention and its problems>> As is well known, in construction work in the field of urban civil engineering, underground walls, surrounding walls of tanks, foundations, etc. are constructed by the muddy water excavation method.

This construction method mainly consists of suspending clay such as bentonite in water, adding dispersants and thickeners, etc. to create muddy water, and filling the mud with it while excavating the ground in a trench or circular cross-section. After excavating to a depth of 1,000 yen, the muddy water inside is replaced with concrete, and the concrete is allowed to harden to construct walls and piles underground.

In this type of construction method, if the excavated ground is permeable, such as gravel ground, muddy water excessively seeps into the surrounding ground and flows out, making it difficult to constantly fill the excavation hole with muddy water.

Therefore, the present applicant has previously developed a muddy water consisting of a vegetable viscous substance dissolved in water and additives such as borax and boric acid, in place of the muddy water whose main component is bentonite.

The viscosity of the muddy water varies over a very wide range from tens of thousands of centipoises to several tens of centipoises by adjusting the hydrogen ion concentration (PH).

In other words, by adjusting the PH, when excavating ground with a large amount of sludge, such as a sand and gravel layer, mud is injected into the drilling hole in a highly viscous state to prevent sludge and reduce sludge. When excavating a small amount of ground, lowering the viscosity can improve excavation efficiency and promote separation of excavated soil.

By the way, in this type of muddy water drilling method, the muddy water used for excavation, including the highly viscous muddy water mentioned above, is reused, and when reusing it, it is necessary to separate the mixed earth and sand.

For separation, the muddy water filling the borehole is pumped up, stored in a recovery tank, and separated based on the difference in specific gravity between the muddy water and the muddy water.

However, especially in the case of soft muddy water with a high viscosity, the following problems occur when collecting the muddy water.

In other words, as mentioned above, muddy water mixed with vegetable viscous substances has an extremely high viscosity.
As with ordinary muddy water, pumping over long distances was extremely difficult and almost impossible.

For this reason, there was a restriction that the recovery tank had to be provided close to the excavation hole.

Furthermore, once excavated soil is mixed into the highly viscous muddy water, there is a problem in that the soil is not easily separated due to its high viscosity.

The present invention has been made in view of these problems, and its purpose is to provide a recovery system suitable for a muddy water excavation method using high viscosity muddy water.

≪Means for Solving the Problems≫ In order to achieve the above object, the present invention mixes a viscosity increasing agent into muddy water in which a viscous substance is dissolved in water to increase the viscosity, and in this state is poured into a borehole. In the mud drilling method, the concrete placed in the excavation hole is replaced with the high viscosity mud water. A connected muddy water recovery line, a viscosity reducing agent supply line connected to the muddy water recovery line, and a line mixer provided on the combined muddy water and viscosity reducing agent mixing line;
It is characterized by comprising a recovery tank connected to the terminal end of the mixing line on the discharge end side from the line mixer.

<<Operation>> According to the muddy water collection system having the above configuration, the viscosity of the muddy water is automatically reduced in the line for collecting the muddy water, so that it can be transported over long distances.

In addition, since the viscosity is lowered and stored in the collection tank, mixed earth and sand can be separated quickly and easily.

Furthermore, the supply amount of the viscosity-lowering agent can be automatically set according to the viscosity of the collected muddy water.

<<Example>> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The figure is an explanatory diagram showing a high viscosity muddy water supply/recovery system to which the present invention is applied. In the figure, 1 is an excavation hole, 2 is a mud water supply system for the excavation hole, and 3 is a recovery system for recovering the mud water in the excavation hole 1.

The supply system 2 is connected to a mixer 4 that mixes a viscous substance, water, and a preservative, a liquid tank 6 that stores muddy water mixed and stirred by the mixer 4, and an outlet side of the muddy water of the liquid tank 6. the muddy water supply line 8, the viscosity-increasing agent supply line 12 which connects the viscosity-increasing agent stored in the stirring tank 10 to the muddy water supply line 8, and the combined muddy water and viscosity-increasing agent mixing line 14. The discharge end of the line mixer 16 is connected to the excavated hole 1.

The recovery system 3 connects a recovery line 22 from a submersible pump 20 disposed in the excavation hole 1 with a supply line 26 for supplying the viscosity reducing agent stored in a storage tank 24, and connects this mixing line. A line mixer 16 is provided on the line mixer 16 in the same manner as above, and the end of the mixing line 28 is connected to the waste liquid tank 30 and the recovery tank 3 on the discharge end side of the line mixer 16.
It is connected to 2.

The supply system 2 operates when the borehole 1 is excavated, and stops operating when the borehole 1 is filled with high viscosity mud. In addition, collection system 3
is activated when the muddy water is replaced with concrete, and stops its operation when the muddy water in the excavation hole 1 is replaced with concrete.

The muddy water collected in the collection tank 32 is added to the muddy water supply line 8 via the pump 34 in a state in which mixed sand and gravel are sedimented and separated. If the slurry has deteriorated due to multiple uses, the recovered muddy water is not sent to the recovery tank 32 but is transferred into the waste liquid tank 30.

Therefore, after the supply/recovery systems 2 and 3 are in operation, the mixer 4 mixes enough mud to replenish the loss of mud in the borehole 1 or the loss due to wastewater separation, and pumps the liquid through the pump 36. All that is required is to replenish the tank 6.

Here, the viscous substance may be a plant viscous substance such as guar gum or locust bean gum, used alone or in combination, which becomes a viscous liquid when dissolved in water. and,
This muddy water is made even more viscous by a viscosity-enhancing agent, that is, an alkalizing agent, increasing the viscosity to tens of thousands of centipoise. is used. Furthermore, the viscosity reducing agent is an acidifying agent, such as aluminum sulfate, aluminum chloride, dilute sulfuric acid, dilute hydrochloric acid, and the like. Therefore, the muddy water stored in the liquid tank 6 and the recovery tank 32 is neutral or weakly acidic, and is stored in a low viscosity state. This low viscosity muddy water is pumped through the submersible pump 38 in the liquid tank 6.
Alternatively, it is sent to the muddy water supply line 8 by the submersible pump 34 in the recovery tank 32. The sent mud is made to have a high viscosity by adding a viscosity increasing agent and mixing by the line mixer 16, and then enters the drilling hole 1.
Exhale inside.

When the drilling hole 1 is filled with high viscosity muddy water, the supply system 2 receives the detection output from a liquid level gauge (not shown).
operation will cease.

Then, the recovery system 3 is driven from the time when concrete is placed in the excavated hole 1.

That is, by driving the pump 20 to pump up high-viscosity muddy water in the excavation hole 1, this high-viscosity muddy water is sent into the recovery line 22.

Immediately before the line mixer 16, the viscosity reducing agent in the storage 24 flows through the supply line 26 into the recovery line 22.

Supply line 26 includes pump 40 and valve 4.
Depending on the discharge pressure of the pump 40, the viscosity-lowering agent enters the line mixer 16 together with the collected muddy water, and is completely mixed as it travels through this interior, and the viscosity-lowering agent passes through the mixing line 28. The mud is sent into the waste liquid tank 30 or the recovery tank 32 or to the waste liquid tank 30. A pressure gauge 46 is provided on the mixing line 28, so that the discharge pressure can be checked at all times. Further, a pair of switching valves 48 and 50 are provided at the tip side of the mixing line 28, and by switching the respective valves 48 and 50, the recovered mud water is switched to the waste liquid tank 30 side or the recovery tank 32 side and the slurry is fed. It's summery.

Note that the pressure indicated by the pressure gauge 46 indicates the pressure after the viscosity has decreased. Therefore, by proportionally controlling the opening degrees of the valves 42 and 44 according to this value, appropriate viscosity management can be achieved. In other words, the optimum value of the degree of viscosity reduction is determined, and the valves 42 and 4 are adjusted according to this value.
By setting the opening degree of 4, it is possible to feed mud without the liquid being too biased towards the acidic side or causing difficulty in feeding mud.

<<Effects of the Invention>> As explained in detail in the examples above, according to the present invention, in the method of turning a viscous substance into high viscosity slurry using a viscosity increasing agent and injecting it into an excavation hole,
Since the collected mud water can be continuously fed into the collection tank in a state where the viscosity is immediately reduced, there is no difficulty in transporting it, and it is suitable, for example, when there is no collection tank near the excavation site. In addition, since the liquid properties can be controlled during mud feeding, it is easy to reuse it after collection.

[Brief explanation of drawings]

The figure is an explanatory diagram showing a high viscosity muddy water supply/recovery system according to the present invention. 1...Drilling hole, 3...Mud water recovery system, 16
... Line mixer, 20 ... Pump, 22 ...
Mud water recovery line, 26... viscosity reducing agent supply line, 28... mixing line, 16... line mixer.

Claims (1)

[Claims] 1 Mix a viscosity increasing agent into muddy water in which a viscous substance is dissolved in water to increase the viscosity, and in this state pour it into an excavation hole, and then pour concrete into the excavation hole into the high viscosity muddy water. In the muddy drilling method, a pump sucks up high viscosity muddy water in the borehole, a muddy water recovery line connected to the discharge end of the pump, and a viscosity reducing agent connected to the muddy water recovery line. Consisting of a supply line, a line mixer installed on the mixing line of the combined muddy water and viscosity reducing agent, and a recovery tank connected to the end of the mixing line on the discharge end side from the line mixer. High viscosity mud water recovery system for mud drilling method featuring: