JP2012246730A - Method for constructing earth retaining wall - Google Patents

Abstract

The present invention relates to a method for constructing a retaining wall and the structure thereof. In the conventional retaining wall construction method, the retaining wall has a double structure, which increases the construction period and costs. Is to solve it.
SOLUTION: A retaining wall for soft ground is drilled into a soft ground by a deep mixing method, and a solidified material slurry 1b is sprayed and mixed in-situ to mix and mix in the drilled hole. This is a method for constructing a retaining wall in which a reinforcing core material 5 is inserted into the hole before the soil cement is solidified.
[Selection] Figure 1

Description

  The present invention relates to a method for constructing a retaining wall in soft ground.

  Conventionally, a retaining wall constructed for ground excavation in soft ground is a passive resistance as shown in FIG. For the purpose of enhancing the safety, a safe and inexpensive mountain retaining is adopted by combining the ground improvement as the leading beam by the deep mixed processing method.

JP 2010-144469 A

  However, in the conventional method of constructing the retaining wall, as shown in FIGS. 7 to 8, the ground improvement body is arranged in a flank shape in parallel with the retaining wall, and further, the improved flank shape is improved. The improved body is arranged in a beam shape perpendicular to the body. Therefore, since the double improvement body of the soil cement column wall and the uplifted improvement body is constructed in the retaining wall portion, and they are constructed by separate heavy machinery, the construction period becomes longer. The cost will increase. The construction method and structure of the retaining wall according to the present invention have been proposed in order to solve such problems.

  The gist of the construction method of the retaining wall according to the present invention and the purpose of achieving the object by solving the above problems of the structure is to drill the retaining wall for the soft ground by the deep mixed processing method. The solidifying material slurry is jetted and stirred and mixed in-situ, and the reinforcing core material is inserted into the drilled hole before the stirred and mixed soil cement in the drilled hole is solidified.

In the agitation / mixing, an appropriate amount of a retarder is added together with the solidifying material slurry and then applied.
In addition, a beam-like improvement body is provided in a direction orthogonal to the mountain retaining wall, and the improvement body is formed inside the mountain retaining wall in a lattice shape in plan view.

According to the method of constructing the retaining wall of the present invention, it becomes possible to construct a single construction heavy machine by the deep mixing treatment method, and as shown in FIG. 4, the time required for assembly and removal of the construction heavy equipment is shortened, Compared with the conventional construction period, the construction period is significantly shortened, resulting in cost reduction.
In addition, there is an excellent effect that the active side pressure is reduced by the presence of a certain width of the improved body by the deep mixing treatment method on the back surface of the mountain retaining wall, and the size of the core material of the mountain retaining wall can be reduced. .

Sectional drawing (A) which shows the principle of the deep mixing processing method in the construction method of the retaining wall which concerns on this invention, Sectional drawing which penetrates a stirring blade into a soft ground, and a top view (B) of a drilling hole, A stirring blade It is sectional drawing (C) of the state which pulled up and the improvement construction was completed. It is sectional drawing (A) which shows the structure of the mountain retaining wall by the construction method of the mountain retaining wall of the same invention, and a partial enlarged plan view (B) of the mountain retaining wall. It is characteristic curve figure (A), (B), (C) which shows the penetration resistance value of a sample by the difference in the addition amount of a retarder, a table flow value, and vane shear strength. It is the figure which compared the construction period of the mountain retaining method which concerns on this invention, and the mountain retaining method which concerns on a prior art example. It is a top view of the retaining wall by the retaining method according to the present invention. It is sectional drawing of the mountain retaining wall by the mountain retaining method concerning a prior art example. It is a partially expanded plan view of the retaining wall by the retaining method according to the conventional example. It is a top view of the mountain retaining wall by the mountain retaining method concerning the same prior art example.

  As shown in FIG. 1, the method for constructing a retaining wall according to the present invention constructs a retaining wall by a deep mixed processing method instead of a soil cement column wall, and further embeds a core material in the retaining wall. Is the method.

  As shown in FIG. 1 (A), it is a construction method for constructing a retaining wall for soft ground according to the present invention, in which a soft ground is drilled by a high-speed, low-displacement deep mixing method (SDM method), and a solidified material. Spray the slurry and stir and mix in situ.

  The deep mixing treatment method is a method in which a mechanical stirring method and a high pressure injection method are used in combination, and a three-point pile driver is used for the construction method. This deep mixing treatment method uses a special auger screw to suppress soil displacement during construction by performing soil removal while improving soft ground. An improved diameter of about 2 m and a large-diameter improved body are obtained, low displacement construction, and shortening the work period by high-speed mass processing.

  The deep mixing treatment method is not limited to the SDM method, for example, by spraying the solidified material slurry at an ultrahigh pressure while interlocking with compressed air from the tip of the NJP special stirring blade attached to the double tube rod, Includes air-enhanced ultra-high-pressure jet agitating ground improvement method (NJP method: registered trademark) that creates a large-diameter improved body in a short time.

  In addition, as a mechanical agitation method, there is a mechanical agitation method (CDM method) in which a cement-based solidifying material slurry and in-situ soil are agitated and mixed in a soft ground using a processing machine and solidified to a predetermined strength. In addition, as a high-pressure injection type, by adding compressed air from a monitor attached to the tip of a double tube rod and injecting, rotating, and pulling a super high-pressure cement-based hardener in the horizontal direction, Double tube high-pressure jet agitation method (JSG method), which creates a cylindrical solid body, and simultaneously injects ultra-high pressure water in the upper stage and ultra-high pressure hardened material from the lower stage to discharge the slime to the ground. It includes various deep-mixing processing methods such as a method (JEP method) in which particles and a hardener are mixed and stirred to create a large-diameter and high-quality improved body.

  A core material that bears stress before the solid cement or the like in which the agitated / mixed solidifying material slurry is mixed with the in-situ soil in the hole is solidified is inserted into the hole. The core material is H-shaped steel or the like, and is inserted into the soil cement by a vibro method or free fall. One core material is inserted for each hole.

  In the construction of the core material, it is necessary to insert it before the soil cement is solidified after the drilling operation. Even if one of the drilling operations is completed and the core material is immediately inserted, the second set of drilling operations is completed, and the second set of drilling operations is completed. After that, the first set of core materials is inserted. Therefore, since time has passed since the first set of drilling operations (specifically, about 3 to 4 hours), it is necessary to prevent the soil cement from solidifying.

  Therefore, when stirring and mixing the solidifying material slurry and the in-situ soil, an appropriate amount of retarder is added together with the solidifying material slurry as necessary. In determining the addition amount of this retarder, an appropriate amount of the target ground is tested and determined in advance.

  For that purpose, as shown in FIGS. 3 (A) to 3 (C), the retarder (Geoliter 10 manufactured by Floric) is made into 4 types of 0%, 2%, 4% and 6%, and kneaded. 1, 2, 3 and 4 hours after the rise, a penetration resistance test, a table flow test (based on JIS Z5201), and a vane shear test were performed. The temperature of the soil cement sample is 15.8 ° C. From the viewpoint of workability and expression strength, 2% is optimal as the amount of retarder added.

  Further, as shown in FIGS. 2B and 5, a beam-like improved body is provided in a direction orthogonal to the retaining wall, and the improved body is arranged in a lattice shape in plan view on the inner side of the retaining wall. Form. Further, as shown in FIG. 2 (A), assuming that the working side pressure acts up to the intersection of the working slip line and the improved range, there is an improved soil (improved body 4), so the range in which the working side pressure acts. Reduce.

  As shown in FIGS. 1B and 1C, the three-point pile driver 1 is installed on the soft ground 2 and the special auger screw is rotated by the drive motor 1a by the deep mixing method according to the present invention. Then, it is made to penetrate into the soft ground 2, and the solidified material slurry 1b is injected at a high pressure from the tip of the screw, and the soil 3 is simultaneously discharged.

  Then, together with the solidifying material slurry 1b, a required amount (for example, about 2%) of a retarder is contained and injected.

  As shown in FIG. 2 (B) with the three-point pile driver 1, after the first set of drilling and ground improvement, the second set of drilling is continuously performed along the outer peripheral wall. When the second set of holes and the ground improvement are completed, the three-point pile driver 1 is moved to the position of the third set, and the H-shaped steel 5 is inserted into the first set of holes. The insertion pitch of the H-shaped steel 5 is, for example, 1200 mm and the length in the penetration direction is about 9 m. In the conventional SMW method, the insertion pitch is 900 mm. Therefore, the core material weight is reduced by about 25% in the method of the present invention.

  The insertion of the H-shaped steel 5 into the improved hole 4 can be made to be sufficiently inserted even by the dead weight of the H-shaped steel 5 and the vibro hammer by adding a retarder. Since the hardening of the improved body 4 also proceeds, the H-shaped steel 5 may be inserted by starting a vibro hammer.

  Thereafter, the work for inserting the H-shaped steel 5 is delayed by two sets of the drilling holes of the three-point pile driving machine 1. Thus, as shown in FIGS. 2 (B) and 5, the mountain retaining wall is constructed along the outer wall by the high speed low displacement deep mixing method (SDM method), and then in a direction perpendicular to the mountain retaining wall by the improved body 4. The cut beam-shaped improvement body 6 is constructed in a lattice shape at appropriate intervals.

  As shown in FIG. 2A, the improved body 6 is formed by drilling with the three-point pile driving machine 1 and high-pressure jetting the solidifying slurry 1b while pulling up to a required height. Then, it is pulled up by just stirring with the stirring blade of the three-point pile driving machine 1 to make it empty.

  Thereafter, excavation of the soft ground 2 is started. As shown in FIG. 2B, excavation is performed along the excavation surface so that the flange surface inside the H-shaped steel 5 is exposed. As shown in FIG. 2 (A), a lateral sheet pile 7 is inserted into the empty portion at the top of the H-shaped steel 5. Thereafter, the inner part of the improved body 4 is excavated.

  When excavating the improved body 4, the water stoppage is maintained by taking care not to crack the improved body 4 by cutting a working machine such as a bucket or a giant breaker. Depending on the progress of the excavation work, one or more stages of cut beams 8 are constructed according to the excavation depth. Drill to the root cutting bottom 9.

  As described above, the mountain retaining wall 4 is constructed on the soft ground 2. As shown in Fig. 4, as in the upper construction period showing the conventional construction method, there is an assembly of heavy machinery, etc. due to the mixing of the SMW construction method and the deep mixing treatment method, and there is an overlapping work of moving and carrying out, but the construction period is lengthened. As shown in the lower construction schedule showing the construction method of the present invention, the duplication work is eliminated and only the deep mixing treatment construction method is used. Therefore, the construction period of the retaining wall is greatly shortened, and the construction cost is 1 compared to the conventional construction cost. It is reduced by about a percent.

  The mountain retaining wall 4 is used as a formwork for the outer side of the outer wall for new construction, an inner formwork is formed inside the improved body 4, and concrete is placed between them, and is cast as an underground outer wall of the new building. You may make it use it integrally with construction concrete.

  The method for constructing a retaining wall according to the present invention constructs a retaining wall by using an improved body and a core material (H-shaped steel 5 or the like) for soft ground.

1 three-point pile driver, 1a drive motor,
1b Solidified material slurry,
2 soft ground,
3 Earth removal,
4 Improvements,
5 Core material (H-shaped steel, etc.)
6 Cut beam improvement body,
7 Horizontal sheet pile,
8 Cut beams,
9 Root cutting bottom,
10 SMW.

Claims (3)

The retaining wall for the soft ground is drilled into the soft ground by the deep mixing method, and the solidified slurry is sprayed and mixed in-situ. The stirred and mixed soil cement in the hole is solidified. Inserting a reinforcing core material into the drilling hole before construction,
The construction method of the retaining wall characterized by this. When stirring and mixing, add an appropriate amount of retarder together with the solidifying material slurry,
The method for constructing a retaining wall according to claim 1. Providing a beam-like improvement body in a direction perpendicular to the retaining wall, and forming the improvement body in a lattice shape in plan view on the inner side of the retaining wall;
The method for constructing a retaining wall according to claim 1 or 2.

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