JPS5945047B2 - Method for creating underground hardened layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for creating a hardened layer in the ground by injection, making use of the characteristics of water glass, a solution hardening agent, and a suspension hardening agent.

Conventionally, in order to create a hardened layer, after polling, a solution hardening agent mainly composed of sodium silicofluoride or sodium bicarbonate, a suspension hardening agent such as water glass or cement milk, and an injection liquid of either water glass are used. However, the former has good permeability but lacks strength and is expensive; the latter has good strength and is inexpensive, but lacks permeability. This is a major drawback from the viewpoint of widening the permeation range as much as possible, and has an even greater drawback that homogeneous injection cannot be expected.

Many attempts have been made to harmonize these two types of curing agents, but since both of them are instant-setting, if they are injected at the same time through one injection tube, the injection will quickly become clogged. If one is injected and then the other is injected using another injection tube, the desired effect cannot be achieved because one has already hardened.

In addition, solution-based hardeners are extremely superior to suspension hardeners in terms of permeability, so they have no choice but to be widely used. The biggest drawback is that it reduces the volume of the hardened part and creates a gap between it and the impermeable soil layer.

On the other hand, suspension hardeners can compensate for the above-mentioned drawbacks because they absorb syneresis water using the reaction heat generated by the reaction between cement particles and water. Therefore, a hardened layer can be created.

The present invention aims at harmonically injecting a solution hardening agent and a suspension hardening agent into a geological formation with a relatively high porosity, and achieved this purpose by the method described below.

That is, with an injection pipe having three flow paths and an injection nozzle,
The water glass, solution hardening agent, and suspension hardening agent are each introduced into the ground separately, and the water glass and suspension hardening agent are first injected into the ground, and then the water glass and the suspension hardening agent are injected into the ground. If you switch over and inject this, the penetrating suspension hardener, which has a slower reaction rate than a solution-based hardener, will first be sent into the surrounding ground, and then immediately after that, The jet of solution-based hardener, which has a fast reaction rate and excellent permeability, guides the suspended hardener already in the ground and diffuses into it, and the suspended hardener that is guided and diffuses into the ground is exposed to the heat of reaction. It absorbs the syneresis water of the solution-based curing agent induced by the method and increases the strength of the permeable layer.

This switching timing and injection ratio are calculated from the soil quality, porosity, and reaction rate of the hardening agent, but it is important to move the injection nozzle to the mixing trajectory range of the injection agent and increase the injection pressure of the hardening agent that will be injected later. By doing so, it is possible to increase the induced diffusion of the previously injected permeable layer and create a complex mixed layer, and it is possible to achieve even greater effects depending on the purpose and target stratum.

The above-mentioned production method can only achieve its purpose by pumping the reactive curing agent into each part separately using an injection pipe with three flow passages, and quickly switching the liquid delivery.
An embodiment of the injection tube used in the present invention will be described below with reference to the accompanying drawings.

Of course, it goes without saying that the present invention can be practiced with injection pipes other than those in this embodiment as long as they have three-flow passages.

Reference numeral 1 denotes an injection tube consisting of a triple tube consisting of an inner tube 2, an outer tube 3, and a middle tube 4 interposed between the inner tube 2 and the outer tube 3. A spring 5 is applied to the lower end of this injection tube 1. A head 7 having a built-in differential pressure valve 6 and a downwardly directed injection hole 11 is installed, and the injection hole 11 of this head 7 is connected to the inner pipe 2 via the differential pressure valve 6, and each inner Injection nozzles 8.9.10 provided on the side wall of the injection tube 1 are connected to the respective passages of the tube 2, the outer tube 3, and the inner tube 4, so that injection can be performed separately from each nozzle.

In addition, a pit can be attached to the lower end of the head 7.
A screw 12 is threaded so that water is injected from the injection hole 11 through the differential pressure valve 6 when polling is performed.

In the present invention, the ground is polled using the above-mentioned injection pipe 1. When polling is performed, water is injected into the inner pipe 2, and the water is poured into the injection hole 11 while the differential pressure valve 6 is kept open.
While injecting water from the pit, polling is performed using the pit, and when the desired depth is reached, water injection is stopped and switched to water glass.
This is supplied to the inner tube, and a suspension curing agent is also supplied to the passage formed by the inner tube 2 and the middle tube 4, and suspended with water glass from injection nozzles 8 and 9 provided on the side wall of each injection tube 1. A fixed amount of the hardening agent is injected into the injection tube 1 while rotating it, this injection is temporarily stopped, and the solution hardening agent supplied to the passage in the outer tube 3 is further injected into the injection liquid in the same manner as above. Nozzle 1
A certain amount is injected from 0, stopped, and then the injection pipe 1 is
The water glass and suspension curing agent are injected while rotating and raised over a certain range, and the above operations are repeated sequentially to perform intermittent injection.

In addition, if the injection nozzle is moved within the injection trajectory range, the injection tube can be moved to a film-like trajectory or a semicircular trajectory, thereby making it possible to create hardened layers of various shapes.

Since the present invention is constructed as described above, there are no gaps between the hardened layers in the ground or the generation of syneresis water, which conventionally occur after the hardened layer is created, and the ground and the hardened layer are in close contact with each other, creating a stable hardened layer. Furthermore, there is no need to perform the conventional cement injection work after forming the hardened layer, which improves work efficiency and saves labor.

[Brief explanation of the drawing]

The drawing shows an embodiment in which a part of an injection pipe used for forming a hardened layer according to the present invention is partially cut away. 1...Injection tube, 2...Inner tube, 3...
... Outer pipe, 4 ... Middle pipe, 5 ... Spring, 6 ... Differential pressure valve, 7 ... Head, 8, 9, 10. ...Injection nozzle, 11...
...Injection hole, 12...screw.

Claims (1)

[Claims] 1. An injection pipe having a ball flow passage and a tip injection nozzle that communicates with each flow passage is inserted into the ground to a predetermined depth, and water glass is suspended through the flow passage through the water glass and its Mihara passage. After simultaneously injecting a predetermined amount of a turbid hardening agent, a predetermined amount of water glass is further simultaneously injected from the leading path and a predetermined amount of a solution hardening agent from the ball flow path to form a hardened layer in the same injection portion. A method for creating an underground hardened layer characterized by: 2. In the method for creating a hardened underground layer as set forth in claim 1, the injection pipe is rotated or raised or rotated and raised so that the injection nozzle is moved to the area where the injection agent has been mixed, and the first step of injection is performed. The injection pressure during the second stage injection was made higher than the injection pressure during the second stage injection.