JP3052106B2 - Construction method of prestressed underground continuous wall - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a continuous underground wall in which a vertical prestress is introduced to improve the tensile strength of concrete.

[0002]

2. Description of the Related Art Conventionally, a method of introducing prestress into a continuous underground wall by a post tension method is disclosed in, for example,
It is known from US Pat. That is, as shown in FIG. 11, a PC steel material 4 having a fixing part 3 at a lower end is disposed near an excavation side ground 2 a in an excavated trench 1, and is replaced with a stable liquid such as muddy water to concrete 5. After the concrete is hardened, tension is applied to the PC steel material 4 to introduce a vertical prestress to the concrete underground wall 6, so that after excavation of the excavation side ground 2a, the back soil of the retaining side ground 2b is excavated. The pressure prevented the basement wall 6 from sagging (the concave portion on the hill side and the convex side on the excavation side). In the figure, 7 is a guide wall, 8 is the ground surface, and 9 is an excavation plan surface of the excavation side ground 2a.

[0003]

However, in such a prior art, the wall surface of the underground wall 6 is in direct contact with the excavation side ground 2a and the retaining side ground 2b, and prestress is introduced in the vertical direction. At the time, a large frictional force was generated between the wall surface of the underground wall 6 and the ground, and it was difficult to effectively introduce prestress. In other words, when prestress is applied to the ground 2a on the digging side of the underground wall 6, the concrete near the ground 2a on the digging side is contracted by the tension of the PC steel material 4. The concrete could not be sufficiently shrunk due to a large frictional force generated in the opposite direction between the side ground 2a.

[0004] It is an object of the present invention to effectively apply a prestress to a continuous underground wall without introducing a frictional force between the wall and the ground when the prestress is introduced into the underground continuous wall. It is in.

[0005]

The construction method according to the present invention comprises:
Installing the partition plate 16 in the groove excavated together with the reinforcing cage 13 together with the reinforcing cage 13;
A step of inserting the steel member 22 into the groove inside the reinforcing rod cage 13, between the partition plate 16 and the excavation side ground 15 a, and between the element separating steel member 18 at both ends of the reinforcing rod cage 13 and the inner surfaces of both ends of the groove. Leave a stable liquid such as muddy water,
6, a step of placing concrete 31 while replacing it with a stable liquid such as mud water only in a region surrounded by the steel material 18 at the both ends of the ground and the retaining ground 15b, and a PC steel material after the concrete 31 is hardened. The method includes a step of introducing a prestress at 22 and a step of solidifying the remaining stable liquid such as muddy water.

[0006]

[Function] The stable liquid remaining between the partition plate and the ground serves as a lubricant between the concrete basement wall and the ground when prestressing the poured concrete with PC steel. Also, it does not generate frictional force due to the ground against the underground wall. Since the partition plate serves as a formwork material at the time of placing concrete, the concrete surface can be finished finely, and the underground wall can be used as it is as an outer wall of an underground structure. The remaining stabilizer is solidified after the introduction of the prestress, so that it does not hinder the subsequent work.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. First, as shown in FIG.
After filling with muddy water (stabilizing liquid) 11 and excavating to a predetermined depth with an excavator 12 as in the prior art, a reinforcing rod cage 13 is suspended by a wire 14 with a base and built in a groove 10 as shown in FIG. Put in. In this case, a partition plate 16 large enough to cover the entire surface thereof is vertically attached to the side of the reinforcing bar 13 facing the excavation side ground 15a, and the partition plate 16 is attached to the groove 1 along with the reinforcing bar 13.
Set in 0. 17 is a guide wall, 15b
Is the mountain on the mountain side.

FIG. 3 (plan view) shows the reinforcing bar 13 and the partition plate 1.
6 is shown in an enlarged manner. The partition plate 16 is made of the reinforcing bar 1
3 is attached to the element partition steel member 18 (only one side is shown) at both ends, and is fixed to the rebar basket 13 by using a fixing member 19 for concrete formwork, a round steel 20 and a separator 21 for formwork. .

Next, as shown in FIG. 4, the PC steel material 22 inserted into the whole linear sheath is temporarily fixed to the upper end portion thereof with the suspending steel material 23 horizontally, and is suspended with the wire 24 together therewith. As shown in FIG. 5 (a plan view of one element), the PC steel material inserted into the inside of the reinforced cage 13 and at a plurality of places near the excavation side ground 15a of the underground wall of one element to be constructed and inserted into the sheath 22 is suspended on the guide wall 17 by the suspension steel material 23.

FIG. 10 shows an example of the PC steel material 22 inserted into a set of sheaths. PC steel material 2 inserted in the sheath of this example
2 is to insert a plurality of unbonded PC steel materials 25 into a steel sheath 26 having a circular cross section connected by screws and to project only the upper and lower ends, and to fill the sheath 26 with grease for the purpose of preventing corrosion or the like. The upper end of the sheath 26 is closed by a lid 27 so that concrete does not enter, and a fixing member 28 for concrete is connected to the lower end. The fixing member 28 has a flange 30 larger than the outer diameter of the sheath 26 in a short steel pipe 29 penetrating the lower end of the PC steel material 25.
Is provided.

After the PC steel material 22 inserted into the sheath is installed as described above, as shown in FIG. 6, between the partition plate 16 and the excavation ground 15a, and between the element steel 18 at both ends and both ends of the groove 10. The muddy water 11 is left between the inner surface and the concrete 31 while the muddy water is replaced only in a region surrounded by the partition plate 16, the retaining ground 15 b, and the element steel 18 between the elements.

After the concrete 31 has hardened and has sufficiently developed strength, the upper end of the PC steel material 25 is tightened with a jack on the top end surface of the concrete wall, and when a predetermined tension is obtained, as shown in FIG. The upper end of the PC steel material 25 is fixed by the fixing tool 32 to introduce prestress. When tension is applied to the PC steel 25 in this way, concrete 3
1 is compressed in the vertical direction, but since the muddy water 11 remaining between the partition plate 16 and the excavation ground 15a acts as a lubricant, the excavation ground 15a No frictional force acts, and a desired prestress can be introduced without hindrance. As the fixing device 32, a nut-type fixing device is preferably used so that the PC steel material 25 can be re-tensioned and released.

After the introduction of the prestress, as shown in FIGS. 8 and 9, a steel pipe 33 is inserted and fixed in the vicinity of the partition steel member 18 at both ends, that is, between both ends of the partition plate 16 and the excavation ground 15a. Partition plate 16 and excavation ground 15
The muddy water 11 is confined and solidified by a known muddy solidification method to obtain solidified mud 11a. The steel pipe 33 is pulled out when the self-supporting of the solidified mud 11a is confirmed. 8 and 9, reference numeral 34 denotes a steel material 18 for partitioning the element 18 at both ends in order to secure an area for placing the concrete 31.
It is an iron plate which seals between the hill side ground 15b.

[0014]

According to the present invention, a partition plate is installed together with a steel cage in an excavated trench, concrete is poured, and a stable liquid such as muddy water remains between the partition plate and the ground. PC
After the prestress is introduced by applying tension to the steel material, the remaining stable liquid such as muddy water is solidified, so that the following effects are obtained.

When the stabilizing liquid left between the partition plate and the ground gives prestress to the poured concrete with PC steel, the role of the lubricant between the concrete basement wall and the ground is obtained. However, since no frictional force due to the ground is generated on the underground wall, prestress can be effectively applied. As a result, the following effects can be expected.

(1) The wall thickness can be made thinner than the conventional prestressed underground continuous wall, and the construction cost is reduced. (2) Large underground continuous walls require a long period of time for preparation work, excavation work, rebar basket building work, etc., but the work days can be shortened by slimming down the wall thickness. (3) Since the amount of deflection of the underground continuous wall is significantly reduced by the effective introduction of prestress, the settlement of the surrounding ground is small, and the influence on the nearby structures is also reduced. (4) As the wall thickness is reduced, the amount of waste muddy water or mud disposal becomes smaller, which is effective as a measure for treating industrial waste. (5) Since the wall strength is large, it is also possible to increase the vertical interval of the shoring support, and the work efficiency of excavation work and frame work is improved.

Since the partition plate serves as a formwork material at the time of placing concrete, the concrete surface can be finely finished, and the underground wall can be used as it is as an outer wall of an underground structure.

The remaining stabilizer is solidified after the introduction of the prestress, so that it does not hinder subsequent operations.

Since the partition plate is attached to the reinforcing bar cage and installed in the groove together with the reinforcing bar cage, the partition plate can be efficiently installed and positioned.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an excavation step in an example of a construction method according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a step of installing a reinforcing rod cage.

FIG. 3 is an enlarged cross-sectional view of the same.

FIG. 4 is a longitudinal sectional view showing a step of installing a PC steel material inserted into a sheath.

FIG. 5 is a transverse sectional view of the same.

FIG. 6 is a longitudinal sectional view showing a concrete placing step.

FIG. 7 is a longitudinal sectional view of a prestress introducing step using a PC steel material inserted into the sheath.

FIG. 8 is a vertical cross-sectional view showing a process of solidifying muddy water left between the partition plate and the excavation ground.

FIG. 9 is an enlarged cross-sectional view of the same.

FIG. 10 is a side view of a PC steel material inserted into the sheath.

FIG. 11 is a longitudinal sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Groove 11 Mud 13 Reinforcing cage 15a Excavation side ground 15b Retaining side ground 16 Partition plate 22 PC steel material inserted in sheath 31 Concrete

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E02D 5/18-5/20 E02D 5/34-5/46 E02D 5/58

Claims (1)

(57) [Claims] 1. A method of placing concrete in a dug trench by replacing it with a stable liquid such as muddy water, and then applying tension to a PC steel buried in the concrete to introduce prestress in a vertical direction. In the method of constructing a stress-introduced underground continuous wall, a step of attaching a partition plate 16 to a reinforcing bar cage 13 together with the reinforcing bar cage 13 in the groove, and a PC inserted into a sheath.
A step of inserting the steel member 22 into the groove inside the reinforcing bar cage 13, a step of inserting the steel member 1 between the partition plate 16 and the excavation side ground 15 a, and between the element bars at both ends of the reinforcing bar cage 13.
8 and a stable liquid such as muddy water remain between the inner surfaces of both ends of the groove,
A step of placing concrete 31 in a region surrounded by the partition plate 16, the retaining ground 15 b, and the element steel 18 at both ends while substituting a stable liquid such as muddy water,
A step of introducing a pre-stress in the PC steel material 22 after the concrete 31 is hardened, and a step of solidifying the remaining stable liquid such as muddy water, etc. Law.