JPH0362848B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention involves excavating the ground, forming a retaining wall on the wall surface, and applying a preload to the strut in order to support the retaining wall by the strut. Regarding the method of jacking up struts for feeding purposes.

<Conventional technology> In general, in deep underground excavation, in order to prevent subsidence of the surrounding ground, axial force is introduced in advance to all struts by jacking in response to the stress applied to the retaining wall at each stage of root cutting. The strut preload method is applied.

As shown in Fig. 6, the conventional method of introducing axial force into the strut by jacking is to form a retaining wall on the wall of the excavated ground 19 with H-shaped steel 21 and soil mortar 20, and to attach the retaining wall to the strut. After erecting uprights 22, 22 made of H-shaped steel along the sides so that the webs 22a, 22a are horizontal, and placing backfill concrete 23, 23 between them and the retaining walls, the intermediate section 25 is constructed.
Then, a large number of struts 24 made of H-shaped steel with screw jacks 26 (see Fig. 7) attached to the grooves are passed between the ribs 22 on both sides at appropriate intervals, and both ends of each strut are connected to the ribs 22 on both sides. It is fixed to the risers 22, 22 with bolts or the like. Then, reaction force receiving plates 27, 27, 27, 27 were attached to the struts 24a, 24b at both ends of the screw jack 26 with bolts, as shown in FIG. Hydraulic jacks 28, 28 to hydraulic pump 2
9 to apply a predetermined compressive axial force to the struts on both sides, and in this state, fully extend and tighten the screw jack 26 by hand, and remove the hydraulic jack 28 and the reaction force receiving plate 27.

However, in the conventional method described above, the four reaction force receiving plates 27, which are quite heavy, must be fixed to the strut 24 with bolts, and two hydraulic jacks 28 must be installed between the reaction force receiving plates, which makes the work difficult. The drawback is that it is time-consuming and does not improve efficiency.
Also, the position 25 of the screw bolt 26 on the strut 24
As shown in FIG. 6, this is not constant, so the work place must be moved frequently in the direction of the strut, which also has the disadvantage of not increasing efficiency. Furthermore, if the ribs 22, 22 on both sides are not parallel, a diagonal piece 30 (see Fig. 6) will be required to fill the gap between the connecting part of the strut 24 and the rib 22, and its fabrication and installation will be time consuming. It also has the disadvantage of being expensive.

<Object of the invention> Therefore, the object of the present invention is to easily and quickly install a hydraulic jack, and to efficiently introduce axial force to each strut without moving the work place in the direction of the strut.
To provide an economical method for jacking up a strut that does not require a diagonal piece even when the strut crosses obliquely.

<Structure of the Invention> In order to achieve the above object, the method for jacking up a strut according to the present invention is to apply a preload to a strut supporting a retaining wall by using an H-shaped steel with a web horizontally erected. Drill a hole in the flange on the strut side, place a jack between both flanges of this upright, insert the rod of this jack into the hole, extend this rod and press the end of the strut. , is characterized in that a preload is applied to the strut.

<Examples> Hereinafter, the present invention will be explained in detail with reference to illustrated examples.

FIG. 1 is a longitudinal cross-sectional view of the raised side of a general mountain stopper (see FIG. 6), and FIGS. 2 and 3 are cross-sectional views of FIG. 1, respectively.

In these figures, 1 is an H-shaped steel installed vertically as a retaining wall (see 21 in Fig. 6), and 2 is an H-shaped steel installed horizontally along the retaining wall with the web 2a. (See 22), 3 is backfill concrete poured between this raised wall 2 and the retaining wall (see 23), 4 is an end plate 5 joined to the end face, and 4 is approximately perpendicular to the raised face 2. H constructed by
Stray beams made of shaped steel (see 24), 6, 6,...
... are bolt holes drilled in two rows in the axial direction above and below the web 2a in the flange 2b on the strut side of the upright 2, and 7 and 8 are bolt holes 6 and 9 in the end plate 5. It is fitted, and the sill 2 and the strut 4
4 long bolts and nuts connecting 10, 10
11 is a steel spacer arranged on the upper and lower surfaces of the web 2b in contact with the flange 2c on the side of the retaining wall 1 of the above-mentioned upright 2; Hydraulic jacks 12, 12 are arranged between the long bolts 7, 7 in the direction of the strut, and a hydraulic jack 11 penetrates through the bolt holes 6, 6 and presses the center of the end plate 5 of the strut 4 (see Fig. 1).
It is a rod.

The strut 4 extending substantially orthogonally to the upright 2 is
Screw the middle part in the longitudinal direction with 2 screws in the same way as shown in Figure 7.
6, but the conventional reaction force receiving plate 27
The other end has no hydraulic jack 28, and the other end has no hydraulic jack 28.
As shown in the figure, the entire surface of the end plate is brought into contact with the other side and fixed with bolts.

Using the above-mentioned components, jack up the strut 4 according to the following procedure.

First, pass the strut 4 approximately perpendicularly between the ribs 2 and 2 on both sides, and then tighten the screws 26 in the middle.
After manually extending the struts so that both ends of the struts come into contact with the ribs on both sides, the struts 4 and the ribs 2 are fixed with bolts and nuts. At this time, the other end (not shown) of the strut 4 is tightly fixed as described above with the above-mentioned bolts and nuts, but the one end is loosely connected with the long bolt 7 and nut 8 as shown in FIG. . Next, the hydraulic jacks 11, 11 shown in FIG. 3 are simultaneously driven by a hydraulic pump (not shown), and the rods 12, 1
2 to the flange 2c via steel spacers 10, 10.
is used as a reaction force receiver to project forward, press the center of the end plate 5 of the strut 4, and push it out to the position shown in FIG. 4, thereby introducing a predetermined compressive axial force into the strut 4. In this state, after driving the steel wedges 13 from the four corners into the gap l created between the flange 2b and the end plate 5, as shown in FIG. Tighten it fully. Next, the rod 12 is recessed, the hydraulic jacks 11, 11 and the steel spacers 10, 10 are removed, and reinforcing plates 15, 15 are fitted from above and below at positions corresponding to the webs 14 of the struts 4 of the upright 2. Finally, three sides around the gap 1 are appropriately closed, non-shrinkage mortar 16 is poured from above to fill the gap, and the jack-up is completed.

In the above embodiment, for example, the belly riser 2 is made of H-shaped steel 400
x 400, the strut 4 can be made of H-shaped steel 300 x 300, the hydraulic jack 11 has a capacity of 50 tons, the long bolt 7 has an outer diameter of 22 mm, and a length under the neck of 100 mm, and the gap l created by the jack is 5 to It is 20mm. Moreover, the compressive strength of the non-shrinkage mortar 16 is five times or more that of the introduced compressive stress, and has sufficient performance as a gap filler.

In the above embodiment, the rods 12 of the jacks 11, 11 are inserted into two rows of upper and lower bolt holes 6, 6, which are normally drilled for attachment in the riser 2 made of H-shaped steel.
12 penetrates and presses the center of the end plate 5 on the end face of the strut 4, so there is no need for drilling and it is extremely easy to set the jack. Even when a wedge-shaped gap is created between the flange 2b and the raised flange 2b, compressive axial force can be introduced into the strut without the need for a diagonal piece as in the conventional case, which improves work efficiency and is also economical.

<Effects of the Invention> As is clear from the above explanation, the method for jacking up a strut according to the present invention uses an H-shaped steel belly with a horizontally erected web when applying a preload to a strut supporting a retaining wall. A hole is drilled in the flange on the strait side of the upright, and a jack is placed so that it receives the reaction force from the flange on the stopper side, making effective use of the space between the flanges of this upright. A rod is inserted into the hole, and the rod is extended to press the end of the strut to apply a preload to the strut, so the jack can be easily and quickly attached to the riser. All you have to do is move the jack up work position along one side of the ramp, so even if the strut and the ramp are diagonal, jacking up is not difficult, greatly contributing to the efficiency and cost reduction of the strut preload construction method. do.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the belly riser used in the present invention, FIGS. 2 and 3 are cross-sectional views of FIG. 6 is a plan view showing the conventional strut preload construction method, and FIG. 7 is a detailed view of the part shown in FIG. 6. 1...Holding wall (H type steel), 2...Horizontal (H
(shaped steel), 3... Backfill concrete, 4... Stray beam (H-shaped steel), 5... End plate, 6, 9... Bolt hole, 7... Long bolt, 8... Nut, 10...
...Steel spacer, 11...Hydraulic jack, 12...
... Rod, 13 ... Steel wedge, 15 ... Reinforcement plate, 16 ... Non-shrink mortar.

Claims (1)

[Claims] 1. When applying preload to the strut supporting the retaining wall, a hole is drilled in the flange on the side of the strut, which is an H-shaped steel with a web installed horizontally, and a jack is placed between both flanges of the strut. A method for jacking up a strut, characterized in that a rod of the jack is inserted into the hole, and the rod is extended to press the end of the strut to apply a preload to the strut.