JP3856585B2 - Construction method of grid-like ground improvement body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of construction methods in which soft ground is improved into a continuous wall shape, and a grid-like ground improvement body is created in plan view, and more specifically, stress transmission performance and water shielding performance The present invention relates to a construction method for creating a high-quality grid-like ground improvement body having a sufficiently high necessary function.
[0002]
[Prior art]
Conventionally, for the purpose of liquefaction countermeasures, etc., as shown in FIG. 5, a wall-like ground improvement continuous to a soft ground (liquefied ground) P is performed, and a lattice-like ground improvement body 1 is created in plan view. This is disclosed in, for example, Japanese Patent Publication No. 4-54004 (Japanese Patent No. 1930164) of the present applicant and is well known. The grid-like ground improvement body 1 is formed to a depth that allows it to be embedded in a natural or artificial non-permeable bottom base (non-liquefied ground) Q, and ensures necessary functions such as stress transmission performance and water shielding performance.
[0003]
In order to obtain the necessary functions such as stress transmission performance and water shielding performance of the grid-like ground improvement body 1 sufficiently high, the two-way wall-like improvement bodies 1a, 1b, ... of the grid-like ground improvement body 1 are properly continuous. Of course, it is very important that the wall-like improvement bodies 1a... 1b.
[0004]
As a means for creating the lattice-like ground improvement body 1 described above, a mechanical stirring deep layer mixing method is generally used. The mechanical stirring deep mixing method is a method in which cement-based solidified material and raw ground are stirred and mixed by a processing machine, and soft soft ground is solidified to improve the ground. For example, (1) the ground improvement method described in Japanese Patent Publication No. 7-86225 uses an auger machine W provided with a single-axis or multi-axis rod R as a processing machine as shown in FIG. By the general mechanical stirring deep layer mixing method, the ground is improved to a continuous column wall shape, and a lattice-like ground improvement body is created.
[0005]
(2) The ground improvement method described in Japanese Examined Patent Publication No. 62-54929 improves the ground into a continuous column wall shape by a general mechanical stirring depth mixing method, as shown in FIGS. As described above, the construction order of every other preceding improved body a, a and intermediate succeeding improved body b is devised so that construction failure is unlikely to occur.
[0006]
(3) In the ground improvement method described in Japanese Patent Application Laid-Open No. 4-247114, the ground is improved into a flat plate wall by a mechanical stirring deep mixing method using a chain cutter type processing machine.
[0007]
In addition to the mechanical stirring deep layer mixing treatment method, it is also known that a jet stirring deep layer mixing treatment method is used as means for creating the lattice-like ground improvement body 1 described above. The injection-type agitated deep mixing method uses a processing machine to inject cement-based solidified material with water and air to the surrounding ground at high pressure, and stir and mix the solidified material with the original ground to solidify the soft original ground. This is a method of ground improvement. For example, as shown in FIG. 8, for example, a general jet-type agitation deep layer mixing method uses a boring machine M provided with an injection pipe K having a high-pressure injection nozzle S such as a solidified material at the tip. To do. For example, (4) In the ground improvement method described in Japanese Patent Application Laid-Open No. 10-237859, a high-pressure injection nozzle such as a solidifying material at the tip of the injection pipe is devised and constructed for the purpose of efficient discharge of in-situ soil. ing.
[0008]
(5) The ground improvement method described in Japanese Patent Laid-Open No. 10-18283 is an injection in which an injection nozzle such as a solidified material that swings in the wall thickness direction of a wall-like improvement body to be constructed is provided at the tip of the injection pipe. The ground improvement is made into a flat plate wall shape by the mixed stirring deep mixing method, and the lattice-like ground improvement body is created.
[0009]
[Problems to be solved by the present invention]
The general mechanical agitation deep mixing method used in the ground improvement method of the prior art {circle over (1)} has a feature that construction efficiency is good, but on the other hand, it is difficult to ensure construction accuracy. The rod of the processing machine used at the time of construction is soft when there is a large difference in hardness of the target original ground, such as the rigidity in the horizontal direction is low, and one of the grounds for stirring the holes is harder than the other. It progresses little by little toward the ground. For example, in the case of construction conditions in which a prior improvement body is constructed and a subsequent improvement body is constructed several days later, the preceding improvement body exhibits a considerable improvement strength, so that the tip of the rod is directed toward the soft ground. Lattice ground improvement body which is easy to displace and has been created by creating a gap which is poor construction between the preceding improvement body a and the subsequent improvement body b as shown in FIGS. This will cause deterioration of the water shielding performance and stress transmission performance.
[0010]
The problem in ensuring the accuracy of construction is that, at the stage of ground improvement in a continuous wall shape in one direction, the advancement improvement body is not developed so much in the advancement improvement body, such as the next day or the next day at the longest. Since it is only necessary to devise and deal with the construction order as in the ground improvement method described in (2) above, it does not matter much. However, the construction of the intersection 1c of the grid-like ground improvement body 1 shown in FIG. 5 is different from each construction condition such as the number of processing machines used for the ground improvement and the scale of the ground improvement work. The construction plan must be formulated so that the entire improvement of the grid-like ground improvement body can be successfully constructed before the advanced improvement body exhibits much improvement strength according to the conditions or only by devising the construction sequence. The degree of freedom is small. In addition, there are many cases where it is very difficult to make a good construction plan according to the above conditions, such as when the ground improvement work is large, and as a result, poor construction is likely to occur. As the construction depth increases, the problem in securing the construction accuracy becomes more serious, and in particular, in the case of large-depth construction, construction defects are more likely to occur, and it is more difficult to create a high-quality grid-like ground improvement body. It becomes.
[0011]
The mechanical stirring deep mixing method used in the ground improvement method of the above prior art (3) is a unique method that uses a chain cutter type processing machine to improve the ground into a flat wall shape. When converting, there is the hassle of having to build a chain cutter after drilling with a boring machine or earth drill, etc., and it is an inefficient and unsuitable method to build the whole lattice-like ground improvement body . It is a construction method with good construction efficiency only when long straight ground improvement is performed.
[0012]
The jet type agitated deep mixing method used in the ground improvement method of the above prior art (4) has the feature that construction failure is less likely to occur, but on the other hand, the construction efficiency is poor and it is not economical. It can be said that this method is unsuitable for applying to all construction work in the ground improvement work. In addition, the wall thickness of the columnar wall-shaped ground improvement body to be constructed is unnecessarily large, which necessitates useless solidifying material and is also uneconomical.
[0013]
The ground improvement method of the prior art {circle over (5)} has the same problems as the ground improvement method of the prior art {circle around (4)} because it uses the jet-type stirring deep mixing method. In addition, a thick injection pipe with a nozzle for injection of solidified material that swings in the wall thickness direction of the wall improvement body to be constructed must be inserted into the ground, so use a boring machine or earth drill. Holes must be drilled in advance, which is more inefficient.
[0014]
Therefore, the object of the present invention is the respective characteristics of both methods by functionally combining both the mechanical stirring deep mixing method with good construction efficiency and the jet stirring deep mixing method with good construction accuracy. It has good construction efficiency and good construction accuracy, and can create a high-quality grid-like ground improvement body with sufficiently high necessary functions such as stress transmission performance and water shielding performance. In the same way, it is possible to create a high-quality grid-like ground improvement body with sufficiently high necessary functions such as stress transmission performance and water shielding performance, as well as the number of processing machines used for ground improvement and ground improvement work. It is an object of the present invention to provide a method for constructing a grid-like ground improvement body that is easy to devise a construction plan according to each construction condition such as a scale and has a high degree of freedom in the construction plan.
[0015]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the construction method of the grid-like ground improvement body according to the invention of claim 1 is:
In the construction method in which the ground improvement is performed in a continuous wall shape of the soft ground P , and the lattice-shaped ground improvement body 1 is created in plan view,
The intersection 1c of the grid-shaped ground improvement body-out removal, longitudinal and lateral walls shaped improved body 1a, and 1b and construction by machine械式stirred Deep Mixing Method,
The intersection 1c is to ground improvement by jet stirring Deep Mixing Method, the longitudinal and lateral walls shaped improved body 1a, that mutually lattice-like ground improvement body 1 with integrated 1b to complete formation Features.
[0016]
The construction method of the grid-like ground improvement body according to the invention of claim 2 is:
In the construction method in which the ground improvement is performed in a continuous wall shape of the soft ground P , and the lattice-shaped ground improvement body 1 is created in plan view,
The wall-like improvement body 1a (or 1b) in either the vertical or horizontal direction when viewed in plan from the grid-like ground improvement body 1 is a continuous state that crosses or crosses the intersection 1c by a mechanical stirring deep mixing method. The other wall-like improvement body 1b (or 1a) is also applied by the mechanical stirring deep mixing method until the position approaching the intersection 1c with the one wall-like improvement body,
The intersection 1c is to ground improvement by jet stirring Deep Mixing Method, the longitudinal and lateral walls shaped improved body 1a, that mutually lattice-like ground improvement body 1 with integrated 1b to complete formation Features.
[0017]
Embodiments and Examples of the Invention
As shown in FIG. 5, the construction method of the grid-like ground improvement body according to the present invention is to improve the ground into a continuous wall shape of the soft ground P, and to create a grid-like ground improvement body 1 in plan view. It is suitably implemented as a construction method when doing.
[0018]
An embodiment of a method for constructing a grid-like ground improvement body according to the invention of claim 1 will be described with reference to FIGS. As shown in FIG. 1A, first, except for the intersecting portion 1c of the grid-like ground improvement body, the wall-like improvement body 1a in the lateral direction as viewed in plan is preliminarily applied by the mechanical stirring depth mixing method. . Subsequently, as shown in FIG. 1B, the wall-like improved body 1b in the vertical direction as viewed in plan is applied by the same mechanical stirring depth mixing method. Of course, the construction order of the wall-like improvement bodies 1a and 1b in the vertical and horizontal directions may be reversed.
[0019]
As an example of the mechanical stirring deep layer mixing method, a method using the auger machine shown in FIG. 6 as a processing machine is performed as an example.
[0020]
Finally, as shown in FIG. 1C, the intersecting portion 1c is constructed by a jet-type agitation deep mixing method. As an example of the jet-type agitation deep mixing method, a method using the boring machine shown in FIG. 8 as a processing machine is performed as an example.
[0021]
1A to 1C are developed in the vertical and horizontal directions, and as shown in FIG. 2, a grid-like ground improvement body 1 in which the wall-like improvement bodies 1a, 1b,. Created.
[0022]
The construction plan of the construction method of the grid-like ground improvement body according to the invention of claim 1 is, for example, using two auger machines and one boring machine, and the construction of the lateral wall-like improvement body 1a. The construction of the vertical wall-shaped improvement body 1b... Is individually assigned to separate auger machines, and the sequentially formed intersection portions 1c are processed by a boring machine. In this way, it is possible not only to prevent mistakes such as forgetting simple construction, but also to perform construction efficiently.
[0023]
Next, an embodiment of the construction method of the grid-like ground improvement body according to the invention described in claim 2 will be described with reference to FIGS. As shown in FIG. 3A, first, the wall-like improvement body 1a in the lateral direction when the lattice-like ground improvement body is viewed in plan is constructed in a continuous state crossing the intersecting portion 1c by the mechanical stirring deep mixing method. . Subsequently, as shown in FIG. 3B, the vertical wall-shaped improvement body 1b is constructed by the same mechanical stirring depth mixing method until a position approaching the intersection 1c with the horizontal wall-shaped improvement body 1a. . Of course, the construction order of the wall-like improvement bodies 1a and 1b in the vertical and horizontal directions may be reversed. If the longitudinal direction of the grid-like ground improvement body 1 to be constructed is constructed in a continuous state crossing the intersecting portion 1c like the wall-like improvement body 1a, the construction efficiency can be improved. As an example of the mechanical stirring deep layer mixing treatment method used for the construction of the vertical wall-shaped improvement body 1b, a construction method using the auger machine shown in FIG. 6 as a processing machine is carried out as an example. In the mechanical stirring deep layer mixing processing method used for the construction of the lateral wall-shaped improvement body 1a, a method using the auger machine shown in FIG. 6 as a processing machine is also implemented as an example. Alternatively, use a chain cutter type processing machine to improve the ground in the form of a flat plate wall, as in the mechanical agitation deep mixing method used in the ground improvement method of Prior Art 3 , which is suitable for improving the long straight ground. Construction methods can also be implemented.
[0024]
Finally, as shown in FIG. 3C, the intersecting portion 1c is constructed by a jet-type agitated deep mixing method. As an example of the jet-type agitated deep mixing method, a method of using the boring machine shown in FIG. 8 as a processing machine is performed as an example.
[0025]
3A to 3C are expanded in the vertical and horizontal directions, and as shown in FIG. 4, both of the wall-like improvement bodies 1a, 1b,. 1 is created.
[0026]
The construction plan of the method for constructing the grid-like ground improvement body according to the invention of claim 2 is the same as the construction plan of the construction method of the grid-like ground improvement body according to the invention of claim 1, for example, two augers. Using a machine and one boring machine, each of the auger machines specializes in the construction of the horizontal wall-like improvement body 1a ... and the vertical wall-like improvement body 1b ... The formed intersection 1c is processed by a boring machine. If it carries out like this, it will be possible not only to prevent mistakes, such as a simple forgetting construction, but also to construct efficiently, as with the construction plan of the construction method of the grid ground improvement object concerning the invention of the above-mentioned claim 1.
[0027]
[Effects of the present invention]
The construction method of the grid-like ground improvement body according to the present invention is a two-way method by functionally combining both a mechanical stirring depth mixing treatment method with good construction efficiency and a jet type stirring depth mixing treatment method with good construction accuracy. It is possible to create a high-quality grid-like ground improvement body having sufficiently high necessary functions such as stress transmission performance and water shielding performance, which has both good construction efficiency and good construction accuracy.
[0028]
In addition, the construction method of the grid-like ground improvement body according to the present invention uses a spray-type agitated deep mixing method that is flexible in the improvement range for the ground improvement at the intersection. If the ground is improved, it is possible to create a high-quality grid-like ground improvement body having sufficiently high necessary functions such as stress transmission performance and water shielding performance even in the case of deep construction.
[0029]
Moreover, the construction method of the grid-like ground improvement body according to the present invention is easy to devise a construction plan according to each construction condition such as the number of processing machines used for ground improvement and the scale of ground improvement work. Great freedom of planning.
[Brief description of the drawings]
FIGS. 1A to 1C are explanatory views showing in plan a construction procedure of a construction method of a grid-like ground improvement body according to the invention of claim 1;
FIG. 2 is a plan view showing an outline of a construction result of a construction method of a grid-like ground improvement body according to the invention of claim 1;
FIGS. 3A to 3C are explanatory views showing the construction procedure of the construction method of the grid-like ground improvement body according to the invention of claim 2 in a plan view; FIGS.
4 is a plan view showing an outline of a construction result of a construction method of a grid-like ground improvement body according to the invention of claim 2. FIG.
FIG. 5 is a perspective view showing an outline when a grid-like ground improvement body is created on soft ground.
FIG. 6 is a side view showing a processing machine used in a mechanical stirring deep layer mixing method.
FIGS. 7A to 7C are a plan view, a front view, and a bottom view showing a construction result of a conventional ground improvement method. FIGS.
FIG. 8 is a front view showing a processing machine used in a jet-type stirring deep mixing method.
FIGS. 9A to 9C are a plan view, a front view, and a bottom view showing a construction result when construction failure occurs in the mechanical stirring deep layer mixing method.
[Explanation of symbols]
P Soft ground 1 Lattice ground improvement body 1a, 1b Wall improvement body 1c Intersection

Claims (2)

In the construction method to improve the ground into a continuous wall shape of soft ground, and to create a grid-like ground improvement body in plan view,
Except the intersections of the grid-like soil improvement material, the longitudinal and lateral walls shaped improved body and construction by machine械式stirred Deep Mixing Method,
The intersection is to ground improvement by jet stirring Deep Mixing Method, characterized in that complete forming a grid soil improvement material obtained by integrating the wall-like improvement of the longitudinal and lateral directions to each other, the grating Construction method of the ground improvement body. In the construction method to improve the ground into a continuous wall shape of soft ground, and to create a grid-like ground improvement body in plan view,
When the grid-like ground improvement body is viewed in plan, either the vertical or horizontal wall-like improvement body is constructed in a continuous state that crosses or crosses the intersecting portion by a mechanical stirring deep mixing method, and the other wall. The shape improvement body is constructed by the same mechanical stirring deep layer mixing method up to the position approaching the intersection with the one wall shape improvement body,
The intersection is to ground improvement by jet stirring Deep Mixing Method, characterized in that complete forming a grid soil improvement material obtained by integrating the wall-like improvement of the longitudinal and lateral directions to each other, the grating Construction method of the ground improvement body.

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