JPH11117289A - Ground improved body creating method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly select impregnant liquids different in flash setting time by mixing and injecting two liquids according to the hardening time of two ground improving flash setting impregnant liquids, or switching passages to inject two liquids in the unmixed state. SOLUTION: When tens sec are required from the mixing to hardening of two flash setting impregnant liquids A, B, the liquids A, B are fed to a mixer 26 from tanks 22, 24 and mixed. The mixed liquid is immediately force-fed to the inner passage 16 of an injection rod 12 by a pump device 36 through a switching device 43 and a connecting port 66. When high-pressure air is required, the high-pressure air is force-fed to an outer passage 14 from a high- pressure air pump 28. When the flash setting liquids A, B' are used, the liquid A is force-fed to the outer passage 14 of the injection rod 12 from the tank 22 through a pump 32 and a switching device 41 without being mixed, and the liquid B' is likewise force-fed to the inner passage 16 from a tank 25. The liquids A, B' are mixed after being injected from a double nozzle. A one-liquid transfer system and a two-liquid transfer system are switched by a switching device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to improvement of soft ground,
The present invention relates to a ground improvement body creation method and a device for building a building foundation, supporting a ground, and the like.

[0002]

2. Description of the Related Art A number of ground improvement body construction methods for forming a consolidated body by injecting an injectable material into a target ground have been developed, but forcibly mixing and mixing the soil of the target ground with the injected material. As a method, for example, there are a method using high pressure injection and a method using low pressure or spontaneous discharge. The high-pressure injection is also called a jet grout method, and air or water may be injected at the same time in order to efficiently cut and agitate the target ground. In addition, the method using low pressure or discharge is also called a mechanical stirring method, and is performed while mechanically stirring with a stirring blade.

Further, the injection material is usually of a two-liquid type consisting of a liquid A and a liquid B. In the case of instantaneous setting, each liquid must be transferred through separate paths so as not to be hardened during the transfer. It has to be said. For example, in the case of high-pressure injection, two liquids are separately sent to the vicinity of the tip of the injection rod using a double pipe, and the two liquids are mixed and injected immediately after mixing.
There is a method of injecting the liquids separately and mixing the two liquids after the injection. As described above, the method of completely separating and transferring the two liquids is applied to a quick-setting injection material having a curing time of several tens of seconds or less.

[0004] On the other hand, in the case of a slow-setting injection material, two liquids A and B are sufficiently mixed in advance in a mixer installed on the surface of the ground, and then transferred to the vicinity of the tip of the injection rod in a single liquid state. Inject into the ground. This method is applied to an infusible material having a hardening time of several tens of minutes.

[0005]

However, in the system in which the two liquids are separately transferred and mixed immediately before or immediately after the injection in the instantaneous injection material, sufficient mixing of the two liquids is not guaranteed, and as a result, the formation is completed. There is a possibility that unevenness may occur in the improved body to be obtained.

[0006] The soil properties of the target ground are not always the same depending on the depth. Therefore, it may be preferable to selectively apply either one that cures literally instantaneously or one that cures in tens of seconds, depending on the soil properties, even if it is called the instantaneous setting. For example, do you need to stop water,
Whether countermeasures must be taken to prevent backflow of the injected material, whether the only purpose is to strengthen the ground, and so on. In places where an inappropriate type of injection material is used, a desired consolidated body may not be obtained, and as a result, uniform formation cannot be performed.

Further, depending on the depth condition of the target ground,
Alternatively, depending on the direction of construction (vertical, inclined, or horizontal), the use of air may or may not be suitable, and thus it is preferable that air supply and stop can be freely selected.

[0008] In view of the above problems, an object of the present invention is to provide a method for forming a ground improvement body by high-pressure injection in order to reliably form a uniform ground improvement body. It is to provide a method that ensures a sufficient mixing state of the material as much as possible, that can appropriately select the type of injection material having different instantaneous setting time, and that can also select the supply and stop of air. .

It is a further object of the present invention to provide a ground improvement body forming apparatus for realizing the above method.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for injecting a target ground using an injection rod having two flow paths and two injection nozzles communicating with the respective flow paths. In the ground improvement body forming method of forming a ground improvement body by rotating and moving the injection rod while injecting the material, a liquid A and a first liquid B of the two-part injection material are supplied before being pumped to the injection rod. After mixing to form a mixture, the mixture is injected under pressure from one of the injection nozzles by pumping the mixture to one of the flow paths of the injection rod,
A first step of supplying high-pressure air to the other of the flow paths and injecting the high-pressure air from the other of the injection nozzles; After mixing the liquid B with the mixed liquid to form a mixed liquid, the mixed liquid is pressure-fed to one of the flow paths of the injection rod to inject the mixed liquid from one of the injection nozzles, and to the other of the flow paths. A second step of stopping the supply of the high-pressure air, and injecting the A liquid of the two-liquid injecting material into one of the flow paths of the injection rod by pressure and injecting the A liquid from one of the injection nozzles. And a third step of injecting the second B liquid from the other of the injection nozzles by pressure-feeding the second B liquid to the other of the flow paths, wherein the first step and the second step The step or the third step is performed by selectively switching according to the target ground.

Further, the present invention includes an injection rod having two flow paths and two injection nozzles communicating with the respective flow paths, and rotates the injection rod while injecting the injection material to a target ground. And a ground improvement body forming apparatus for forming the ground improvement body by moving forward and backward, wherein a mixer for mixing the liquid A and the first liquid B of the two-component injection material before being fed to the injection rod; Means for pressure-feeding the mixture to one of the flow paths of the rod and injecting the mixture from one of the injection nozzles; and supplying high-pressure air to the other of the flow paths to supply the high-pressure air to the other of the injection nozzles. A first mechanism having a means for injecting air, a mixer for mixing the liquid A and the first liquid B of the two-part injectable material before being pumped to the injection rod, and the mixer of the injection rod from the mixer. To one of the channels A second mechanism comprising means for injecting the liquid mixture to inject the mixture from one of the injection nozzles, and means for stopping the supply of high-pressure air to the other of the flow paths; A means for injecting the liquid A of the two-component injection material into one of the paths and injecting the liquid A from one of the injection nozzles, and a means for injecting the second liquid B into the other of the flow paths and the injection nozzle And a third mechanism having means for injecting the second B liquid from the other one of the first mechanism, the second mechanism, or the third mechanism, corresponding to the target ground. And a switching device for switching.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of an apparatus 10 for implementing a ground improvement body forming method according to the present invention. In this method, an injection rod basically having two isolated flow paths is used. As an example of the embodiment, a case where a double tube injection rod 12 is used will be described. An outer flow path 14 and an inner flow path 16 are provided concentrically on the injection rod 12 of the double pipe. As such a double-pipe injection rod, a rod used for a conventional two-liquid quick-set injection material can be applied as it is. A swivel 62 is provided at the proximal end of the double tube injection rod 12, and the swivel 62 has an outer flow path 14 and an inner flow path 1 inside the injection rod.
Connection ports 64 and 66 for connecting the device 6 to the outside are provided respectively. The supply hose 52 is attached to the connection port 64, and the supply hose 54 is attached to the connection port 62. The supply hose 52 is connected to the switching device 41, and the supply hose 54 is connected to the switching device 43.

In the present invention, when using a two-liquid instantaneous injection material, as shown in FIG.
The tanks 22, 24, 25 connected by 43, the high-pressure pump devices 32, 34, 36 for each injection material, the mixer 2
6, and the high-pressure air pump device 38 is arranged.

[0014] Here, in the two-component flash-setting injection material,
Some cure literally instantaneously, while others cure in tens of seconds (specifically, 20 to 60 seconds). In the latter case, there is room for the time to mix and transfer as one liquid on the ground, and the present invention utilizes this point.

First, as a two-component flash-injecting injection material, a liquid A and a liquid B requiring about several tens of seconds from mixing to curing (this liquid B is referred to as a “first liquid B” in this specification). Will be described. The liquid A is prepared in the tank 22, and the liquid B is prepared in the tank 24. The liquid A is, for example, cement milk, and the liquid B is, for example, a curing accelerator such as water glass or a polymer. Tank 2 by switching device 42
2 and the mixer 26, and the tank 24 and the mixer 26. Thereby, the A in the tank 22
The liquid and the liquid B in the tank 24 are respectively sent to the mixer 26, where they are mixed to form a mixed liquid. The mixed solution is immediately sent to the mixed solution pump device 36, and the mixed solution pump device 3
From 6 through the switching device 43, the supply hose 54 and the connection port 66, it is pressure-fed to the inner flow path 16 of the injection rod. at the same time,
High-pressure air is sent from the high-pressure air pump device 28 to the other connection port 64 of the swivel 62 via the switching device 41 and the supply hose 52, and is sent to the outer flow path 14 of the injection rod by pressure.

FIG. 2 shows the double tube injection rod 1 shown in FIG.
FIG. 2 is a schematic cross-sectional view near the tip of No. 2; A pair of double nozzles is provided at an opposite position on the outer periphery near the tip of the injection rod 12. One double nozzle is the core nozzle 17a
And the surrounding nozzle 18a, and communicates with the inner flow path 16 and the outer flow path 14, respectively. Another double nozzle,
It has a core nozzle 17b and a surrounding nozzle 18b, and is also in communication with the inner channel 16 and the outer channel 14. Therefore, when a mixed liquid of the liquid A and the liquid B is pressure-fed to the inner flow path 16 and high-pressure air is pressure-fed to the outer flow path 14, the mixed liquid is injected at a high pressure while being surrounded by the high-pressure air. At this time, the supply of the high-pressure air to the target ground that does not need to use the high-pressure air can be stopped by the switching device 41 or the appropriate valve device 44 in FIG.

Next, a liquid A and a liquid B '(literally, B' in the present specification) which are literally instantaneously cured as a two-part instantaneous injection material.
The liquid is sometimes referred to as “second liquid B”). These liquids, without mixing,
It must be pumped to the outer flow path and the inner flow path of the injection rod 12, respectively. The solution B ′ is prepared in a tank 25 different from the solution B. The liquid A is, for example, cement milk, and the liquid B 'is an instantaneous hardening material for instantly hardening. In this case, the tank 22 and the A liquid pump 32 are
And the switching device 41 is used to connect the A liquid pump 32
And the connection port 64 are connected. As a result, the liquid A is pumped to the outer flow path 14 of the injection rod 12. On the other hand, solution B '
The liquid is supplied from the B ′ liquid tank 25 to the B ′ liquid pump 34. The switching device 43 connects the B ′ liquid pump 34 to the connection port 66.
, The B ′ liquid is pumped to the inner flow path 16 of the injection rod 12. In FIG. 1, the liquid A at this time,
The path of the B 'liquid is indicated by a broken line. At this time, the supply of the high-pressure air is stopped by the switching device 41 or 44. Thus, the solution A and the solution B 'are isolated and the injection rod 1
2 and are mixed at the time of injection from the double nozzle. When one of the liquid B and the liquid B 'is used, the other is stopped from supplying the liquid. Although this switching can be performed by the switching device 43, separate switching devices 45, 46 and the like may be provided to surely perform the switching.

In summary, according to the ground improvement body forming apparatus according to the present invention, it is possible to apply the two-liquid quick-setting injectable material in one of the following three modes using one apparatus. (1) A high-pressure injection of a mixed liquid obtained by mixing a two-liquid injection material (liquid A and liquid B) which cures in several tens of seconds is surrounded by air. (2) In the above (1), only the mixture is injected at a high pressure without surrounding with air. (3) Separately transfer the two-component injection material (liquid A and liquid B ') which is instantaneously cured, and inject high pressure with one surrounded by the other.

The above three aspects can be changed at any time and in any order in the injection material injection step of the construction. That is, it is selectively switched to any one of the three modes as needed. For example, it is possible to design an optimum construction for the soil in accordance with the soil data (such as a column diagram) of the target ground that has been surveyed in advance. Preferably, the switching of each switching device is automatically controlled based on the construction design. Further, it is preferable that the automatic control of the switching device is performed comprehensively together with the rotation rod drive control of the injection rod.

In the above embodiment (1), even the instantaneous injection material is mixed by a special mixer, so that a uniform mixing state can be ensured. Although the mixing time is short, it is possible to reliably form a good compact as compared with the case where the two liquids are separately transferred and mixed at the time of injection.

The mode (2) can cope with a situation where air is unnecessary or air should not be used. For example, there is a case where the air lift effect rather induces air retention in horizontal construction or the like. In addition, since no air is used, sludge can be minimized.

The above-mentioned embodiment (3) corresponds to a situation where instantaneous hardening is required, such as when the purpose is to stop water, or when the injected injected material is formed on a soil which is likely to flow backward. it can.

Finally, a basic construction example of the ground improvement body forming method according to the present invention will be described. First, the target ground is drilled to a predetermined depth. When the injection rod 12 shown in FIG. 2 is also used as a drilling rod, drilling is performed by a cutting bit 78 provided at the tip of the rod. At the same time, the surrounding ground may be cut and stirred by injection of high-pressure water and / or air. When the predetermined depth is reached, the injection rod 12 is rotated and advanced and retracted, and the injection material is injected at a high pressure in any of the above-mentioned planned modes (1) to (3) to form a desired consolidated body. I do. Generally, the injection rod is often moved while being retracted. However, the rod may be moved forward halfway, so that the forward and backward movements are collectively referred to as “forward and backward movement”.

The configuration of the ground improvement body forming apparatus of the present invention shown in FIG. 1 is merely an example, and any apparatus capable of realizing a mechanism capable of executing the injection material injection modes (1) to (3) above. I just need. Therefore, the specific configuration of the tanks for the liquids A, B, and B ', the high-pressure air pump device, the mixer, the high-pressure pump device for the injection material, and the connection between the connection ports of the injection rod and the switching of those connections Can be considered many.
Further, in the embodiment, a double pipe injection rod having a concentric flow path is used. However, the present invention can be similarly applied to an injection rod in which two flow paths are arranged in parallel.

[0025]

As described above, according to the method and apparatus for preparing a ground improvement body according to the present invention, by using a double pipe injection rod, a two-component flash-injection having a curing time of several tens of seconds is used. After the materials are mixed by the mixer, they are transferred to the injection rod as one liquid, and the supply and stop of high-pressure air can be selectively performed. Thereby, a sufficient mixing state of the two liquids can be ensured, and a favorable ground improvement body can be created. further,
By the switching device for controlling the supply of the injection material, the instantaneous setting injection material which hardens instantaneously can be separately transferred to the injection nozzle. By appropriately switching the one-liquid transfer method and the two-liquid transfer method with a switching device, it is possible to design a construction suitable for the soil of the target ground. As a result, a favorable ground improvement body can be created, and the apparatus cost can be reduced and the working efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for implementing a ground improvement body forming method according to an embodiment of the present invention.

FIG. 2 shows a double tube injection rod 12 according to an embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view of the vicinity of the tip of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ground improvement body preparation apparatus 12 Double pipe injection rod 14 External flow path 16 Internal flow path 17a, 17b Nuclear nozzle 18a, 18b Surrounding nozzle 22 A liquid tank 24 B liquid tank 25 B 'liquid tank 26 Mixer 28 High pressure air pump 32 A liquid Pump 34 B 'liquid pump 36 Mixed liquid pump 41, 42, 43, 44, 45, 46 Switching device 52, 54 Supply hose 62 Swivel 64 Connection port 66 Connection port 78 Cutting bit

Claims (2)

[Claims] An injection rod having two flow paths and two injection nozzles respectively communicating with each flow path is used to rotate and advance / retreat the injection rod while injecting an injection material to a target ground. In the ground improvement body forming method for forming an improved body, the liquid A and the first liquid B of the two-part injectable material are mixed to form a mixed liquid before being fed to the injection rod, and then the injection rod is mixed with the liquid. The mixed liquid is pressure-fed to one of the flow paths to inject the mixed liquid from one of the injection nozzles, and high-pressure air is supplied to the other of the flow paths to inject the high-pressure air from the other of the injection nozzles. A first step, and before the pressure feeding to the injection rod, after mixing the liquid A of the two-liquid injection material and the first liquid B to form a mixed liquid, the liquid is injected into one of the flow paths of the injection rod. Inject the mixture from one of the injection nozzles by pumping the mixture And a second step of stopping supply of high-pressure air to the other side of the flow path, and pumping the A liquid of the two-part injection material to one side of the flow path of the injection rod to perform the injection. A third step of injecting the liquid A from one of the nozzles, and forcing the second liquid B to the other of the flow paths to inject the second liquid B from the other of the injection nozzles, A method for forming a ground improvement body, wherein the first step, the second step, or the third step is selectively performed according to the target ground. 2. An injection rod having two flow paths and two injection nozzles communicating with the respective flow paths, wherein the injection rod is rotated and moved forward and backward while injecting an injection material to a target ground. In a ground improvement body forming apparatus for forming a ground improvement body, a mixer for mixing a liquid A and a first liquid B of a two-part injectable material before being fed to the injection rod, a flow of the injection rod from the mixer. Means for injecting the liquid mixture to one of the paths to inject the liquid mixture from one of the injection nozzles, and supplying high-pressure air to the other of the flow paths to inject the high-pressure air from the other of the injection nozzles A first mechanism having a means, and a mixer for mixing the liquid A and the first liquid B of the two-component injection material before being pumped to the injection rod, one of the flow paths of the injection rod from the mixer. Pump the mixture to A second mechanism including means for injecting the mixed liquid from one of the injection nozzles and means for stopping supply of high-pressure air to the other of the flow paths; and two liquids to one of the flow paths of the injection rod. Means for injecting the liquid A of the injectable material and injecting the liquid A from one of the injection nozzles, and feeding the second liquid B to the other of the flow passages and injecting the second liquid from the other of the injection nozzles And a switching device for selectively switching the first mechanism, the second mechanism, or the third mechanism in accordance with the target ground. An improved ground improvement device.