JP2881331B2 - Directional injection injection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses an injection pipe having one or a plurality of discharge holes in the circumferential direction of the injection pipe, and injects and permeates a chemical at a high speed from the discharge holes. Mainly related to a method of improving the ground.

[Conventional technology]

As a method of improving the ground with grout,
Splitting, agitated mixing, etc. are conceivable, but the problem that necessarily arises in performing these operations and construction is the pressure of the chemical (grout) for performing the injection, which is generally called the injection pressure. ing.

This injection pressure can be subdivided into the following: the pressure at which grout penetrates or splits into the ground, the pressure required for the grout to discharge or jet through the discharge holes (nozzles), and the resistance of the pipeline from the grout pump to the tip of the injection pipe. , Which are also commonly referred to as pump pressure or gauge pressure.

Therefore, although there are some unreasonable classifications of methods based on injection pressure such as high-pressure injection / low-pressure injection, etc., the high-pressure injection method refers to the stirring-mixing replacement method, and the low-pressure injection method refers to the permeation injection method. Is an imitation.

As the high-pressure injection method, the JSG method, the column jet method, the CCP method and the like are known. These injection pressures are 200 kgf / cm ² or more, and using an injection pipe having a single discharge hole, while continuously rotating the injection pipe in the circumferential direction, the discharge amount is 50 l per discharge hole. / min or more (however, in the case of the CCP method, about 20 l / min). With such a high discharge pressure and a large amount of grout, the soft ground is cut and destroyed and replaced with suspended grout such as cement. Or trying to mix is the basic technical idea of the construction method.

On the other hand, as a low-pressure injection method, it has long been inherited as a basic idea that the chemical solution is allowed to penetrate into the soil particles without disturbing the ground as much as possible with a slow-setting chemical solution or a flash-setting chemical solution. .

[Problems to be solved by the invention]

However, the former high-pressure injection method, although the improved diameter is large, the biggest disadvantage is that it consumes a lot of labor and cost in discharging and treating the slime, and it also disrupts the ground by cutting and breaking it, It may not be appropriate depending on the ground conditions.

On the other hand, the low-pressure injection method is advantageous in that there are no problems such as slime treatment and the cost is low.However, when a slow-releasing chemical is used, groundwater is present or the ground is uneven. A major problem is that the chemical liquid escapes to a place where the resistance is small, and the chemical liquid does not enter a predetermined position. Further, in consideration of economic efficiency, trying to improve the improvement efficiency by increasing the improvement diameter of one injection hole will promote escape of the chemical solution,
The need to perform injections at multiple locations is also a disadvantage.

The method of injecting the instantaneous drug solution is a method developed to improve inconvenient injection performance such as the escape property of the instantaneous drug solution. In other words, the gap between the injection pipe and the ground where the chemical solution easily escapes,
This is an effective use of the excellent property of instantaneously sealing the gap between strata.

However, splitting is likely to occur, and the deformation of the ground is larger than that of a slow-release chemical, which is disadvantageous in terms of injection management.

Therefore, an object of the present invention is to solve both of the drawbacks in the high-pressure injection method (injection-stirring method / injection-mixing method / injection-stirring replacement method) and the low-pressure injection method, thereby ensuring that the chemical solution can be reliably applied to the intended location. To inject into.

[Means for solving the problem]

Using an infusion tube having one or more discharge holes in the circumferential direction, the discharge pressure of 30 kgf / cm ² or more 200 kgf / cm less than ^2, the solution discharge amount of each of the unit discharge holes, 1~30l / min, the unit Injecting from the discharge hole with the total chemical liquid discharge amount of the discharge amount at the discharge hole being 60 l / min or less, and further stopping the injection pipe having a plurality of discharge holes in the circumferential direction without continuously rotating around its axis. In a state where the discharge direction with respect to the circumferential direction of the discharge hole is fixed, or while changing the circumferential position of the discharge hole of the fill tube at a time interval, At the circumferential position, the solution can be solved by moving the injection pipe in the axial direction to inject the chemical, and at the same time, penetrating the chemical into the ground around the entire injection pipe.

[Action]

The present invention is based on the fact that permeable chemical liquid (grout) is jetted into the ground with directivity from the discharge hole of the injection pipe to perform osmotic injection. The operation is as follows.

In other words, the injection pressure (discharge pressure) is such that the chemical is injected at a high speed in the direction of the discharge hole, and the chemical liquid penetrates the ground with directivity by the energy of the chemical. This action stops when the energy decays. However, there is no direct pressure on the ground in contact with the side of the chemical jet. The injected chemical liquid penetrates into the ground with directivity by such an action, and due to the peripheral surface of the space generated by the penetration of the chemical liquid, the chemical liquid comes into contact with the ground with a large area (independent of the injection) The space where the chemical solution contacts the ground in the case of the conventional low-pressure discharge hole is at most equivalent to the tip having the discharge hole). For this reason, the total area of the permeation surface on which the permeation action is performed is remarkably increased as compared with the conventional permeation area, and the permeability is improved. For this reason, it is possible to perform a reasonable and uniform permeation injection.

Here, considering the permeation limit discharge rate in the conventional low-pressure injection method, even at the ground where penetration conditions are favorable, 20 l / mi
The limit is about n, and if it exceeds this, splitting injection will be performed even with a slow-setting chemical, and the chemical will run toward the weak line almost independently of the gel time.

Even in such a case, if the permeation surface of the target ground through which the injected chemical liquid penetrates can be widened, the permeation injection can be easily performed because the critical permeation amount increases. If we compare this to a general phenomenon, the rain in the evening shower concentrates in a narrow area, so it can not penetrate into the soil and creates a flow on the ground surface, but if the same amount of rain falls over a large area, it will not flow. It will penetrate.

In addition, the flow rate (discharge amount) at which the chemical solution discharged by a pump or the like can penetrate varies depending on the ground conditions and the above-mentioned permeation area of the chemical solution. If the discharge amount exceeds a certain limit, a destructive effect on the ground may be caused depending on the condition. And also seepage without disturbing the gentle ground. Although these are common general knowledge, the present invention is based on these principles, and even if the discharge rate is less than the permeation limit and the alternating layers are uneven, the permeation area is forcibly increased by force. The purpose of the present invention is to dramatically improve the reliability of ground improvement accuracy and improve the efficiency of ground improvement.

The jet force required to penetrate the ground with directivity of the chemical solution is determined by the discharge amount of the pump and the cross-sectional area of the discharge hole. That is, the penetration force is determined by the flow rate and the flow rate of the chemical solution discharged from the discharge hole.

Therefore, when comparing the injection force or the like, it may not be accurate to express them as high pressure and low pressure.
In particular, the instantaneous liquid or suspension-type fluid has higher resistance when passing through the discharge hole than the water or the like due to its properties, and therefore increases the discharge pressure (injection pressure). Due to such a situation, it is impossible to compare the injection force based on only the gauge pressure, and it is not accurate.

The present invention, given that on these jet force, if the discharge pressure is less than 30 kgf / cm ² is small penetration force to the ground in the normal discharge rate of the injection, expansion of the penetration surface can not be expected, also Injection with a discharge pressure of 200 kgf / cm ² or more and a large discharge rate will severely destroy and agitate the ground, so that soil particles and chemicals must be discharged to the ground as slime (similar to the injection agitation replacement method) ), The discharge amount and discharge diameter are adjusted within the range of 1 to 30 l / min and 30 to 200 kgf / cm ² , and one discharge hole (nozzle) is provided according to the current state of the ground. Alternatively, it has been confirmed that the reliability of the injection effect and the injection efficiency can be improved by increasing the permeation area of the chemical solution by using an injection tube having a plurality of discharge holes to achieve more reliable permeation injection.

In the case of uneven ground, the chemical solution penetrates only into the soil layer that easily penetrates with low-pressure injection, and the chemical solution hardly enters other soil layers to be injected. According to the present invention, since the chemical liquid penetrates with directivity in the injection direction and further penetrates therefrom, it is possible to reliably solidify a predetermined area even on uneven ground.

In addition, even when the chemical solution is instantaneous, the directivity of the chemical solution is maintained and penetrates into the ground, and the tree-like injection vein with this penetration axis as a trunk and the penetrating part in contact with it have high reliability. Strong ground improvement is possible.

[Specific configuration of the invention]

 Hereinafter, the present invention will be described in more detail.

First, the experiment performed by the inventors and the results thereof will be analyzed.

As shown in Fig. 3, No. 3 sand with high permeability is used on the bottom of the acrylic cylindrical mold to observe the escape of the chemical.
And in order to observe the permeability in the center part, also use No. 3 sand,
The periphery is filled with small water-permeable No. 7 sand, an injection pipe is installed in the center, and a chemical liquid is injected from the tip in the axial direction at a low pressure (1 kgf / cm ² ) for injection nozzle (general name: metal crown) The same chemical solution is injected at high pressure (100k
gf / cm ² ) was replaced with a discharge hole, and injection was performed. After a certain period of time, injection was performed again by changing the circumferential position of the injection tube by 180 degrees. The used chemical solution is composed of an aqueous solution of No. 3 water glass as a main agent (solution A) and an aqueous solution of glyoxal and phosphoric acid as a curing agent (solution B), and has a gel time of 4 to 6 minutes. The injection speed was 10 l /
min.

As a result, in the case of low-pressure injection (discharge resistance 1 kgf / cm ² ), as shown in FIG. 4, only the highly permeable No. 3 sand solidifies into a cylindrical shape before injection, and a consolidation rate of 55% When the body is obtained and the injection is performed with directivity, it hardens to the small water-permeable No. 7 sand outside the No. 3 sand, and the consolidation rate is 80 with the same injection amount.
%, And a mushroom-like compact as shown in FIG. 5 was obtained. The results show that a large improved diameter can be obtained by injection injection even on such uneven ground. In this case, in the injection injection, a high-pressure chemical solution penetrated the discharge layer formed of No. 3 sand and penetrated to the No. 7 sand portion, and a good solidified body was visually observed. In addition, in the case of low pressure injection, outflow of the chemical solution was observed from the discharge layer on the lower surface through No. 3 sand during the injection, whereas the outflow of the chemical solution in the case of injection injection was extremely small.

On the other hand, as shown in Fig. 6, various types of mixed soil from 1: 1 to 9: 1 of Kibushi clay in No. 7 sand and No. 7 sand in order from the bottom,
On top of this, No. 7 sand was filled in layers using a vibrator, and various experimental injections were performed on the simulated ground with various layers of mixed soil and No. 7 sand. An example of an experiment using a mixed soil consisting of No. 7 sand and Kibushi clay 1: 1 is considered as follows: (1) an injection pipe with a discharge hole with an upper opening, and (2) a radial direction around the tip. (3) using an injection pipe having four discharge holes formed at a position 90 degrees in the circumferential direction radially around the distal end of the injection pipe having a single discharge hole, Is 10l / min, 1kg
f / cm ² discharge port, 10 l / min, 12
With a discharge hole of 0 kgf / cm ^{2 and} a discharge hole of 10 l / min and 60 kgf / cm ² in (3), the same chemical solution as in the above-mentioned experiment was used and the gel time was similarly set to 4 to 6 minutes.

In each of the experiments, the characteristics of the state of injection into the mixed soil layer can be seen, but a hamburger-shaped consolidated body as shown in FIG. 7 was obtained, regardless of the discharge pressure of the discharge holes. When observing the cross section of the mixed soil part in Fig. 7,
When the injection is performed through the low-pressure discharge hole using the injection pipe (1), the injection is performed at a low pressure without jetting, and as shown in FIG. 8, the drug solution escapes along with the randomly generated cleavage vein, and only the cleavage vein of the homogel is removed. On the other hand, as shown in FIG. 9 when the injection pipe having the injection / discharge port of (2) is used, and as shown in FIG. 10 when the injection pipe of (3) is used. It was observed that it was injected with directionality and also penetrated around the homogel.

Furthermore, when the bond strength between No. 7 sand and the mixed soil at the layer boundary was examined, an increase in the strength was observed in the case of injection. Also, if the permeability of the central mixed soil is large,
Although there was almost no difference in the total consolidation rate, it was found that when the permeability of the mixed soil was small, the total consolidation rate was higher in the case of injection.

Through a series of these experiments, the effects of the present invention can be easily estimated. The effects can be listed again: (a) The ground can be improved with directivity (it can be reliably injected into a target area).

(B) Even when the ground is uneven, the escape of the chemical solution is small, and accurate injection is possible.

(C) Since osmotic injection is used, no slime is generated by injection. Therefore, slime treatment for injection is unnecessary.

(D) Infiltration into the target area can be performed regardless of the flow of groundwater.

(E) The bonding strength at the layer boundary can be increased.

(F) The consolidation rate can be increased with respect to the ground or the layer having a small hydraulic conductivity.

On the other hand, the present invention is typically performed according to the embodiments shown in FIGS.

That is, the injection pipe 1 having a plurality of discharge holes 2, 2,... In the circumferential direction, for example, as in the embodiment, and having the discharge holes oriented in the radial direction is used. First, the gap between the ground and the injection pipe is sealed. Therefore, the required amount of the instantaneous solution is injected.

In addition, since this method is not an injection stirring replacement method using water or chemicals, the gap between the injection pipe and the ground must always be sealed, so when the installation of the injection pipe is completed or when it is moved, an appropriate amount of instantaneous grout is used. Is preferably injected.

Next, the discharge pressure is set to 30 to 200 fkg / cm ² , the discharge amount of the chemical from each unit discharge hole is set to 1 to 30 l / min, the total discharge amount of the chemical from each unit discharge hole is set to 60 l / min or less, The injection is performed in a certain step without continuously rotating 1 around its axis.

When the injection in this step is completed, as in the embodiment, the step is raised to the next step, and the injection is performed again in that step.

On the other hand, an injection tube having one injection hole may be used,
In this case, in a certain step, after performing injection in a certain radial direction, in the same step, injection is performed while changing the circumferential position, and if necessary, injection in another direction is performed. When the injection in one step is completed, the same injection is performed in the next step. This method can also be adopted when an injection pipe having a plurality of discharge holes is used.

The discharge pressure in the present invention is 30 to 20 in consideration of the permeation limit discharge amount (injection speed) and injection force for various ground conditions.
0 fkg / cm ² . If the discharge pressure of the discharge hole is low, the reach of the chemical solution will be short, and if the discharge amount is too large, the ground will be disturbed, and the slime of the chemical solution and soil particles will break the seal between the injection pipe and the ground and break the ground or stratum boundary. Escape to etc. For this reason, depending on the condition of the ground, the discharge amount of the chemical solution from each unit discharge hole is 1 to
30l / min, total amount of chemical solution discharged from each unit discharge hole is 60l
/ min or less.

In the conventional low-pressure injection method, even in the ground with good conditions for chemical injection, if the injection speed is at a discharge rate of 20 l / min or more, the pressure of the chemical exceeds the permeation limit to the ground,
Runaway of chemicals or deformation of ground.

However, according to the present invention, since the permeation area can be increased instantaneously and simultaneously with the start of injection, the discharge amount (injection speed) reaching the permeation limit pressure is several times that of the low-pressure injection method. Quantity. However, in consideration of the certainty of the improvement effect, the total chemical solution discharge amount is basically 60 l / min or less. The discharge amount from each unit discharge hole is 1
If it is less than / min, the work efficiency is poor and there is a problem in economy.

As the chemical solution used in the present invention, a solution suitable for permeation injection is used, and the most suitable one is a water glass type solution type. However, depending on the conditions of the target ground, a fine particle type or suspension type chemical may be appropriate. As the gel time, both slow setting and instantaneous setting can be used, but generally, about 2 seconds to 60 minutes is preferable.

Further, if necessary in the present invention, an injection pipe having a plurality of injection holes in the axial direction of the injection pipe can be used.

Next, an example of an apparatus suitable for practical work performed based on the above-described injection theory will be described with reference to FIGS. 11 and 12. FIG.

In order to perform injection, the discharge hole of the injection pipe must be set at the target position on the ground, but the penetration installation by press-fitting and hitting is limited to extremely soft ground, and is generally installed by drilling work with water. You. In the practice, it is desirable to perforate by the injection pipe itself in terms of work efficiency.
Therefore, water for piercing is discharged downward from the tip of the injection pipe, and at the time of injection, in the case of this method, a mechanism is required for discharging and jetting a chemical solution in the circumferential direction of the pipe. For this reason, in this embodiment, an injection swivel having a rotating mechanism and withstanding a high pressure constituted by three flow paths, a detachable injection pipe including three flow paths, and blocking of each flow path by a chemical solution are prevented. 3 to do
Check valve for flow path, and discharge water from below if necessary,
We have developed a tip device that can close the downward water circuit at the time of injection and spray the chemical solution in the circumferential direction of the tube, and can also change the instantaneous connection and loose connection arbitrarily.

Next, the structure will be described together with the construction process. The pumping flow path of the perforated water necessary for the installation work of the injection pipe extends from one or two injection pumps, through the injection hose, the swivel and the three flow path injection pipes, to the tip device section in FIG.

In the case of perforation, the perforated water is pumped using the A channel 11 and the B channel 21. The perforated water in the A and B channels 11 and 21 are A and B respectively.
The liquid B flows downward while pushing the check valves 1 and 2 against the urging force of the spring.
Inside, the liquid A and the liquid B that have passed through the communication hole 40a merge. The combined liquid passes through the filter 41 and goes to the tip. The combined drilling water enters the spool valve operating chamber 43 through the communication hole 42, passes through the shaft hole 44a as it is without depressing the spool valve 44, and from the discharge port 46 through the through hole 45a of the seat 45. Discharged and used for rotary perforation of injection tubes.

When the drilling operation is completed and the chemical solution is injected, the main agent of the chemical solution is pumped into the A flow path and the curing agent is pumped into the B flow path. As in the case of the perforation, mixing is performed once at the tip side of the check valve 2. After
At this time, when a chemical liquid having a flow rate larger than the perforated water is pumped, the spool valve 44 has a tip end which is opposed to a biasing force of the spring due to the pumping pressure.
It is moved to the distal end side until it is press-fitted to the valve seat 47 contained in 45.

By the movement of the spool valve 44, the inlet of each nozzle 48 communicates with the inside of the valve chamber 49. As a result, the chemical solution is exhausted from each nozzle 48 in a direction orthogonal to the axis of the injection pipe because the shaft hole 44a is closed by the valve seat 47, so that there is no place to go.

At this time, the diameter of the discharge hole (nozzle) is set according to the required chemical liquid ejection force (discharge pressure) and discharge amount. In addition, when it is necessary to inject a quick-setting chemical solution for sealing the injection pipe with the ground or improving the soft ground, etc., an additive which has a quick-setting property to the slow-setting chemical solution of the main agent A + the hardener B is used. Add the solution through the C channel.

The liquid C enters the joint 50 while pushing down the check valve 3 against the urging force of the spring, and then passes through the conduit 51 and is mixed with the liquids A and B at the outlet of the nozzle 48. In this way, instantaneous setting of the chemical solution is performed.

Using the above-mentioned mechanism, as an execution work, first, at the time when the drilling operation is completed, the required amount of instantaneous injection is performed, and the injection pipe and the ground are sealed. Next, the pressure-supply of the additive for instantaneous setting is stopped to perform slow-setting injection. The method of injection in the working process can be selected as appropriate, and the selection of each chemical solution for instantaneous or slow binding is free.

In this example, the flow rate of the fluid (discharge amount of the pump)
Since the spool valve is operated to change the flow path of the drilling water and the chemical solution, the discharge amount of the drilling water is small,
It may be inconvenient for slime discharge. In such a case, smooth discharge of slime can be achieved by air or water, or alternate discharge of air and water from the C flow path. In addition, as a supply flow path of perforated water,
A or B channel alone may be used. Further, a double pipe can be used without using a three-flow pipe as in the above example.

In addition, as shown in FIGS. 13 and 14, the number of injection nozzles can be one or three or any other appropriate number.

According to the present invention using this type of apparatus, ground improvement with much higher precision can be performed as compared with the conventional infiltration method.

On the other hand, in a more preferred embodiment of the present invention, the discharge pressure is 40 to 170 kgf / cm ² , and the discharge amount of the chemical liquid from each unit discharge hole is 1.5 to 15 l / min.

〔The invention's effect〕

As described above, according to the present invention, the disadvantages of the conventional high-pressure injection mixing method and the ordinary low-pressure injection method are solved, and the advantages (a) to (f) are obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a typical embodiment of the present invention, FIG. 2 is a transverse sectional view thereof, FIGS. 3 to 10 are schematic views showing experimental conditions and results, and FIG. FIG. 12 is a longitudinal sectional view of an example of the structure of the tip portion, FIG. 12 is a transverse sectional view of the nozzle portion, and FIGS. 13 and 14 are transverse sectional views of other examples of the nozzle portion. 1 ... injection pipe, 2 ... discharge hole (nozzle).

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mineo Murata 2-30-18 Nishiaraihonmachi, Adachi-ku, Tokyo (56) References JP-A-60-203726 (JP, A) (58) Fields surveyed (Int. Cl. ⁶ , DB name) E02D 3/12 101 E02D 3/12 102

Claims (1)

(57) [Claims] [Claim 1] with an infusion tube having one or more discharge holes in the circumferential direction, the discharge pressure of 30 kgf / cm ² or more 200 kgf / cm less than ^2, the solution discharge amount of each of the unit discharge hole, 1～30L / min, the total amount of liquid discharged in each unit discharge hole is set to 60 l / min or less, and the liquid is ejected from the discharge hole, and the injection pipe having a plurality of discharge holes in the circumferential direction is continuously rotated around its axis. Without stopping, and in a state in which the discharge direction with respect to the circumferential direction of the discharge hole is fixed, or the injection pipe having one or more discharge holes in the circumferential direction, the circumferential position of the discharge hole of the injection pipe is changed at time intervals. The directional injection injection is characterized in that the injection pipe is moved in the axial direction at a plurality of circumferential positions to inject the drug solution, and that the drug solution penetrates the ground around the entire injection pipe. Method.