JPH0978564A - Chemical injecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To infiltrate and inject a chemical over a wide range in a short time without cleaving the ground by installing a chemical injecting means on the object ground, and injecting the chemical into the object ground while dynamically controlling the injecting pressure of the chemical. SOLUTION: A injection pipe 1 is inserted into the ground, and a tank 4 is installed on the ground. A pressure control means is connected to the tank 4 so that the internal pressure of the tank 4 can be controlled. The injection pressure of the chemical 5 discharged to the surrounding from the tip of the injection pipe 1 is dynamically controlled. When the liquid pressure is quickly changed, the shearing strength generating no cleavage in the ground can be exerted, and cleavages are rarely generated by high-speed injection. The infiltration range of the chemical is widened, and the injection time can be sharply shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical injection method applicable to water stop works, ground reinforcement works, anchor works, etc. More specifically, the injection pressure or the injection speed is increased / decreased to dynamically move the chemical liquid into the ground. The present invention relates to a method for injecting a chemical liquid.

[0002]

2. Description of the Related Art As a chemical solution injection method, for example, a strainer injection method of injecting a curable chemical solution radially through a large number of injection holes formed in the peripheral surface of a strainer injection pipe,
An outer tube with a backflow prevention function is inserted in the boring hole, an inner tube with a double packer is inserted in the outer tube, and an arbitrary discharge is formed on the outer tube through a limited space area of the outer tube separated by the double packer. A soretanche liquid medicine injection method for discharging a liquid medicine from a hole is known. As the injection form, "penetration injection" that penetrates in all directions around the injection position,
It can be roughly divided into “split injection”, which penetrates radially from the injection position. "Cleavage injection" is ideally "penetration injection" because the chemical solution may be injected into a portion other than the intended improvement range. Regarding the injection conditions of the chemical liquid in the “penetration injection”, static injection is performed at a lower pressure and at a slower speed than in the “split injection”. However, in the “penetration injection”, not only the penetration takes time but also the penetration range is limited to a narrow range. This is more remarkable as the viscosity of the drug solution is higher. Although it is conceivable to increase the injection pressure or the injection speed as a solution to these problems, there is a limit to increase the injection pressure because cracking easily occurs. It is known by some verifications that even if infiltration injection is performed at a low pressure, there is a possibility of cracking in the ground in the ground such as cohesive soil.
In particular, there is always concern about the permeability because it is not possible to confirm the penetration status from the ground to the ground.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a chemical injection method capable of performing permeation injection in a wide range in a short time without splitting the ground. Another object of the present invention is to provide a chemical solution injecting method capable of suppressing the development of the splitting and penetrating the chemical solution into a target range even if partial cleavage occurs.

[0004]

According to the present invention, a chemical solution injection method is provided in which a chemical solution injection means is installed in a target ground and a chemical solution is injected into the target ground by the chemical solution injection means by dynamically controlling the injection pressure of the chemical solution. It is a chemical solution injection method characterized by injecting while. Further, the present invention is to install the chemical solution injecting means in the target ground, in the chemical solution injecting method of injecting the chemical solution into the target ground by the chemical solution injecting means, injecting while dynamically controlling the injection speed of the chemical solution, It is a chemical injection method. Furthermore, the present invention is a chemical solution injection method characterized in that the injection pressure or the injection rate of the chemical solution is repeatedly increased and decreased over time. Furthermore, the present invention is a chemical solution injection method characterized in that the injection pressure or the injection rate of the chemical solution is gradually increased with time.

[0005]

Embodiment 1 of the present invention will be described below with reference to the drawings.

<a> Principle of injection As a result of repeatedly performing various trials in order to improve the permeation performance in the ground, the inventor dynamically controls the injection speed or the injection pressure of the chemical liquid to prevent cracking. It turned out that injection can be performed efficiently. That is, to explain based on the conceptual diagram of the present invention shown in FIG. 1, the injection pipe 1 is inserted into the ground, and on the ground side there is an injection means for dynamically controlling and supplying the injection speed or injection pressure of the chemical solution. It is arranged. In this example, the injecting means is composed of the pump 3 which is operated by the drive source 2, and the rotation speed of the pump 3 is changed so that the injecting speed of the chemical solution 5 in the tank 4 connected to the pump 3 can be arbitrarily controlled. Has become. In addition, a pressure control means (not shown) is connected to the tank 4,
If the internal pressure of the tank 4 is controllable, the injection pressure of the chemical solution 5 discharged from the tip of the injection pipe 1 to the surroundings can be dynamically controlled. In this case, the pump 3 becomes unnecessary. The injection means in the present invention may include a known chemical liquid injection device according to the injection purpose and application, and may have a structure capable of dynamically controlling the rotational speed and the pressure feeding pressure of the drive source of these various injection means. Although only one tank 4 is shown in FIG. 1 in order to facilitate understanding of the invention, a plurality of tanks 4 actually exist depending on the number of materials constituting the chemical solution 5.

FIG. 2 shows an example of a control waveform for dynamically controlling the injection pressure (or injection speed) of the chemical liquid. 2A shows a case where the injection pressure is continuously increased and decreased, and FIG. 2B shows a case where the injection pressure is repeatedly increased and decreased within a range set in a sawtooth shape. C) shows a case where the pulse is gradually increased. These control waveforms are examples, and the present invention is not limited to these waveforms. When controlling either the injection rate or the injection pressure, the pitch, amplitude, and
The cycle or the like has a property of being appropriately selected in consideration of the properties of the liquid medicine and the target ground.

In the prior art, pressure fluctuation can occur during the injection of the chemical solution, which is a phenomenon that results when the injection speed is kept constant. Therefore, the essence of the conventional pressure fluctuation phenomenon is different from that of the present invention.

<B> Reason why splitting does not occur As described above, according to the present invention, penetration injection can be performed without causing splitting by dynamically controlling injection. It is generally said that the ground splitting occurs when an external force exceeds the shear strength of the ground, and the shear strength of the ground is known to have velocity dependence. The present invention was made by paying attention to the material properties of the ground that the shear strength of the ground is improved when the rate of change of load (external force) is fast, and cracking of the ground is caused by changing the hydraulic pressure quickly. By exhibiting shear strength that does not occur, splitting is less likely to occur even by high-pressure injection. Furthermore, the present invention is so controlled that the injection pressure of the chemical liquid drops even if a small-scale splitting occurs partially, and because the chemical liquid functions as a caulking material, even if the pressure rises again, It is possible to avoid the injection pressure from concentrating on the split. Even if a small split occurs like this,
The possibility of developing this cleavage is extremely low, and therefore, the medicinal solution can be penetrated into the intended range.

[0010]

Example 1 The following test was conducted to prove the permeability of the present invention. <A> Test method Using Silas No. 6 (Gs = 2.65, D50 = 0.32, Uc = 1.62), a model ground having a relative density of 40% was manufactured by the underwater drop method. A water glass solution type chemical was used as the chemical. Table 1 shows the formulation of the drug solution (gel time 30 seconds).

[0011]

[Table 1]

The dynamic injection was carried out by setting the maximum injection rate to 5.0 liters per minute and the minimum injection rate to 1.0 liters per minute, and repeating the interval in a certain cycle. Average infusion rate is every minute
It is 3.0 liters. There were two types of injection rate cycles, 15 seconds and 30 seconds. Static injection was also performed for comparison. The above test cases are summarized as follows.

<B> Test Results FIG. 3 shows changes with time in the injection rate in each of the cases 1 to 3, and FIG. 4 shows changes with time in the injection pressure. Regarding Cases 1 to 3 which are conventional static injections, in Cases 1 and 2, the behavior that the injection pressure rapidly rises was not observed. In Case 3, the injection pressure increased about 40 seconds after the start of injection. As a result of visually inspecting the solidified body after the injection of Case 3,
Some homogel was found around the injection hole. On the other hand, looking at Cases 4 and 5 according to the present invention, the maximum value of the injection pressure in each cycle was 300 kPa from the start of injection to 100 seconds.
The maximum value of the injection force in each cycle gradually increases with the degree. The minimum value of the injection pressure in each cycle is 30 in Case 5.
While kPa is about the same as in case 1, in case 4 it is only about 100 kPa.

FIG. 4 shows the relationship between the work (cumulative product of the injection pressure and the injection speed at each time) and time in each of the cases 1 to 5. It can be seen that in Cases 1 to 3 which are static injection, the work increases as the injection speed increases. Further, it can be seen that the period of 15 seconds (Case 5), which is the dynamic injection, is smaller than that of the period of 30 seconds (Case 4), and is about the same as the case 3. Therefore, it is presumed that the effectiveness of the dynamic injection is improved if the cycle is shorter than 15 seconds.

FIG. 6 shows the relationship between the injection efficiency (injection amount per unit time) and work in each of Cases 1-5. In Cases 1 to 3, which are static injections, the injection efficiency increases as the injection speed increases. On the other hand, in cases 4 and 5 of dynamic injection, the period is 30 seconds (case 4).
It can be seen that the injection efficiency is better in the case of the cycle of 15 seconds (case 5). In addition, the injection efficiencies of Cases 4 and 5 were about the same as those when the injection rate was 3.0 liters per minute. Therefore, if the injection period is shorter than 15 seconds,
Dynamic injection has been found to be more effective.

[0016]

Example 2 Next, the same test as in Example 1 was conducted under different conditions. The test case for this example is as follows. The change in injection pressure with time in each case is as shown in FIG.

<A> Cross-sectional shape of the solidified body FIG. 8 shows a cross-section of the solidified body of each of the cases 6 to 10. Cases 6 to 8 which are conventional static injections were as follows. [Case 6] Since the injection was performed at a low pressure, the permeation range was the smallest in the case, and the distance from the injection center varied. [Case 7] Although the penetration range was the largest among Cases 6 to 8, the center of the solidified body was displaced from the injection center. [Case 8] A homogel was found around the injection tube, probably because the pressure after the injection was started was rapidly increased. On the other hand, as for the cases 9 and 10 which are dynamic injection, both the cases 9 and 10 had little variation in the distance from the injection tube, and the case 10 had the widest permeation range.

<B> Volume of Solids FIG. 9 shows the volume of solids in each of the cases 6 to 10 described above. In cases 6 to 8 that are static injection, the volume of the solidified body becomes smaller as the injection pressure is higher, but in cases 9 to 10 that are dynamic injection, the case of dynamic low pressure injection is used. The volume was almost the same as that of No. 6. From this, it was proved that the dynamic injection can obtain the same permeation performance as the conventional low pressure injection.

<C> Compressive Strength FIG. 10 shows the test results when the uniaxial compressive strength was tested in the conventional static injection cases 6 to 8 and dynamic injection case 10. According to the figure, in the case of static injection, it was confirmed that the compressive strength decreases when the limit injection pressure is exceeded as in case 8. Further, it has been proved that the case 10 of dynamic injection has a markedly improved compressive strength as compared with the case 7 of static injection at the same pressure.

[0020]

As described above, the present invention can obtain the following effects by dynamically controlling the injection pressure or the injection rate. <B> Since high-pressure injection is possible without cracking,
Compared with conventional static injection, the permeation range of the drug solution is expanded, and the injection pitch and the number of injections can be reduced. <B> Since splitting does not easily occur even if the injection pressure is increased,
The injection time can be greatly reduced. <C> Repeated rapid changes in the injection pressure or the injection rate can suppress the development of the split even if the split occurs, and the chemical solution can efficiently permeate into the target range. <D> By performing dynamic control according to the characteristics of the chemical liquid and the target ground, it is possible to perform permeation injection over a wide range even with a cement-based highly viscous chemical liquid. <E> The strength of the solid body dynamically controlled and constructed is improved as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an injection principle according to a first embodiment of the present invention.

FIG. 2 is a waveform model diagram for dynamically controlling the injection pressure or the injection rate.

FIG. 3 is a diagram showing changes over time in the injection rate in each case in Example 1.

FIG. 4 is a diagram showing changes in injection pressure with time.

FIG. 5 is an explanatory diagram showing the relationship between work and time.

FIG. 6 is an explanatory diagram showing the relationship between injection efficiency and work.

FIG. 7 shows changes in injection pressure with time in each case in Example 2.

FIG. 8 is a sectional view of a solid body in each case of static injection and dynamic injection.

FIG. 9 is a diagram showing a volume result of a solid in each case of static injection and dynamic injection.

FIG. 10 is a diagram showing uniaxial compressive strength of a solid body in each case of static injection and dynamic injection.

Claims (4)

[Claims] 1. A chemical solution injection method in which a chemical solution injection unit is installed on a target ground and a chemical solution is injected into the target ground by the chemical solution injection unit, wherein injection is performed while dynamically controlling the injection pressure of the chemical solution. , Chemical injection method. 2. A chemical injection method in which the chemical injection means is installed on the target ground and the chemical is injected into the target ground by the chemical injection means, injecting while dynamically controlling the injection speed of the chemical. , Chemical injection method. 3. The chemical liquid injection method according to claim 1, wherein the chemical liquid injection pressure or injection speed is repeatedly increased and decreased over time. 4. The chemical liquid injection method according to claim 1, wherein the chemical liquid injection pressure or injection speed is gradually increased with time.