JPH04198532A - Box culvert and its extending direction integrally-forming construction - Google Patents

Abstract

PURPOSE:To improve the shearing resisting strength of a box culvert by arranging positional-shift-proof projection sections with elastic bodies fitted on, at the one end of a main body, and by forming recessed sections to be fitted on the projection sections, at the other end, to provide the recessed sections with PC steel wire inserting holes. CONSTITUTION:A box culvert is formed by arranging positional-shift-proof projection sections at the one-side end of a main body, recessed sections 4 to be fitted on said projection sections, at the other end, and PC steel wire inserting holes 7. Then, the projection sections 3 are formed in taper shapes at each angle of about 5-30 degrees, and on the dimension, the member is set to be of about 150mm, and the projection width (l) is set to be about 100-200mm, and the projection height (t) is set to be about 20-50mm, and the elastic bodies 8 of rubbers or the like are fitted on the whole surface. After that, a plurality of the box culverts with the projection and recessed sections formed on are laid, and they are horizontally fitted on each other. As a result, a shearing force due to a load is dispersed, and the culverts can be prevented from being positionally shifted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a precast box culvert used for sewers, underground passages, etc., and a construction method for integrating the box culvert in its extension direction.

[Conventional technology]

Conventionally, the joint structure of precast box culverts has been improved and various construction methods have been used to prevent joints from separating or shifting after installation.

As a joint structure, for example, as shown in FIG. 8, there is a structure in which a notch a is provided in a portion of the left and right or upper and lower wall end faces so that box culverts can be fitted into each other. This joint structure allows the thick portion of the joint to resist displacement in the horizontal or vertical direction.

Another method is to introduce a relatively low prestress in the extension direction of the box culvert that has been laid to prevent the joints from separating or shifting due to bending moments.

[Invention or problem to be solved]

However, with the above joint structure, the thickness of the joint can only be about half of the maximum thickness of each member. Particularly in the case of vertical displacement, the fact that only half the thickness of the top or bottom plate is sufficient to resist the shear forces acting on the cross joint.

Furthermore, in the conventional prestress introduction method, the amount of prestress introduced is low, making it difficult to sufficiently counter bending stress. However, if a prestress that is sufficient to withstand bending stress is introduced, there is a problem in that manufacturing errors in the box culvert end face may cause local bearing stress failure or concrete falling off around the end face due to hoop cheekbones.

On the other hand, as a method to prevent the joint from shifting or separating, in addition to method 1, it is also possible to strengthen the foundation ground by installing pile foundations or reinforced concrete foundations, which may prolong the construction period. It also requires a large amount of expense.

Therefore, in order to solve the above-mentioned conventional problems, the present invention has developed a box culvert that can be fully integrated in the extension direction by introducing appropriate prestressing, and a box culvert that can be integrated in the extension direction using this hook culver 1. The purpose is to provide an integrated construction method.

[Means to solve the problem]

In order to achieve the above object, the box culvert of the present invention has a plurality of trapezoidal convex portions having a tapered surface on one end surface of the box culvert main body, and a recessed portion that can fit with the convex portions on the other end surface, The present invention is characterized in that a plurality of insertion holes for inserting prestressing steel materials are provided in the longitudinal direction of the box culvert body, and an elastic pad is attached to one end surface of the box culvert.

In addition, in the box culvert integrated construction method in the extension direction using the box culverts described above, when laying box culverts in succession, after laying the box culverts on the excavated and leveled ground, When laying ＼-1.
The method is characterized in that after the box culvert is laid while the concave or convex portions of the box culvert that will be laid later are interlocked and in close contact, a tensioning PCM material is inserted into the insertion hole to introduce prestress.

[Effect]

In the present invention, a plurality of trapezoidal convex portions and concave portions having tapered surfaces that can be fitted into each other are formed on the end face of the box culvert. Therefore, when a plurality of box culverts are laid, the front and rear hockskarno\-1 or the rear culverts do not fit into each other. The uneven mating parts move to resist the forces that tend to shift at the seams due to their own weight or external forces. At this time, by providing a plurality of fitting parts, it is possible to disperse the shearing force due to the load.

In addition, P is inserted into the insertion hole provided in the box culvert body.
By inserting and tightening Cf14 I'll, prestress is introduced in the longitudinal direction, and separation due to opening of the joint part due to bending moment or displacement in the longitudinal direction can be prevented. At this time, by pasting rubber or resin material on the end face, even if more prestress than before is introduced, the compressive force applied to the end face is evenly distributed, and the end face concrete is prevented by the local bearing pressure caused by the problem of end area degree. It is possible to prevent the crushing of the concrete or the falling off of the end face concrete I due to the hoop tenon.

In this way, the present invention makes the box culvert itself a structure that is effective against slippage, and by further introducing prestress into the box culvert, it becomes possible to integrate the box culvert in the extension direction, which was previously difficult.

〔Example〕

Next, the present invention will be specifically explained based on embodiments shown in the drawings.

Figure 1 is a front view of the box culvert of this embodiment, Figure 2
The figure is a side view thereof, FIG. 3 is a plan view thereof, and FIG. 4 is an enlarged view of a fitting portion.

Referring to FIGS. 1, 2, 3, and 4, the hook carver 1 of this embodiment has a protrusion for preventing slippage on one end surface 2 of the hook carver I/main body 1. 3 and the other end face 4
A recess 5 that can be fitted thereto is formed in the holder. The shape of the convex part 3 was made into a tapered shape with a tapered surface 6 provided on the side surface of the convex part, as shown in FIG. 4, in consideration of ease of fitting during installation.

In addition, the taper angle α is set in consideration of working effectively against misalignment, workability at the time of installation, and to prevent extreme increased stress from occurring in the prestressing steel material due to the horizontal component of the vertical load when the design load is applied. Alternatively, the angle may be approximately within the range of 5 to 30 degrees.

Also, as for the size of the protrusion, it is desirable that it has sufficient resistance against shearing force.For a box culvert with a thickness of 150 mm, the width of the protrusion should be +00+n.
m -200mm, height t of protrusion is 2Onon-50m
A value of about m is appropriate. It is desirable to arrange as many of these protrusions as possible on the side walls of the box culvert, and to arrange about 1 to 3 protrusions on the upper and lower floorboards depending on the situation. Additionally, it is desirable to reinforce the areas around the convex portions and concave portions with reinforcing bars or the like.

7 is a PC steel material 9 for introducing prestress that penetrates from one end surface 2 to the other end surface 4 of the box culvert l.
This is the insertion hole. In this embodiment, four locations are provided, but the number can be increased or decreased depending on the conditions, or the cross-sectional area of the PC steel material can be increased or decreased.

Reference numeral 8 denotes an elastic body that is attached to one end surface 2 of the box culvert in order to disperse the prestress force over the entire cross section. This elastic body is made of rubber or resin, and may be, for example, a sandwich of a raw rubber layer sandwiched between sponge rubber layers, or a raw rubber layer alone. The thickness of the elastic body is approximately 5 mm to 15 mm before being integrated by prestressing, and 3 mm to 5 m after being integrated.
It is desirable that the elasticity of the material be approximately 100 m and maintain its elasticity over a long period of time. This elastic body 8 is applied over almost the entire thickness of the box culvert member and around the entire circumference.

The bending moment or shear force acting on a box culvert increases or decreases depending on the length of the span set during design.

Therefore, if the shear strength of the above-mentioned convex part is lower than the shear force of the design load, or if it is lower than the bending tensile stress due to the introduced prestress or the bending moment when the design load is applied, this design span should be You can either shorten it or increase the thickness of the box culvert.

Next, with reference to FIGS. 5(a), (+)), and (C), the method of integrating the box culvert in the extension direction will be explained.

First, as the first step, as shown in (al), the buried position of the box culvert 1 is excavated and the ground surface 11 is leveled. In some cases, sacrificial concrete 12 is placed in consideration of the properties.

Then, as a second step, as shown in (b), the ground surface 11
Discarded concrete constructed on top or on ground surface 11
Lay mortar 13 on top of 1 and 12, and install box culvert 1 on top of 1 and 12. At this time, the concave part 5 of the box culvert 1b to be installed later is engaged with the convex part 3 formed in the previously installed box culvert la, and the box culvert is laid in close contact.

Finally, as the third step, insert Pcl material 9 for tension into the insertion hole 7.
is inserted, and the installation is completed by applying a predetermined prestress and integrating. The prestress value at this time must be such that the combined stress with the bending compressive stress caused by the design bending moment generated in the extension direction of the box culvert will not cause compressive failure of the concrete.

In addition, as a tensioning method, as shown in Fig. 5 (C1), the entire section may be tensioned at once, or as shown in Fig. 6, the fixing tool 10a is It is also possible to provide partial tension in each short section.The latter is better from the viewpoint of construction accuracy, but in terms of workability and the ability to introduce prestress over the entire section, the former is better. It is more convenient. When selecting the tensioning method, it is sufficient to use one of them, taking into account the situation at the site.

In addition, an elastic material such as rubber or resin is sandwiched between the joint surfaces.
It is possible to disperse the stress when the press 1 is introduced. Therefore, it is possible to prevent end face breakage due to bearing stress. In addition, by increasing the thickness of the elastic body, it is possible to give flexibility to the integrated box culvert, which prevents joint displacement due to ground subsidence, even in locations with weak ground support such as soft ground. It becomes possible to follow.

As mentioned above, according to the box culvert integration method of the present invention, integration in the extension direction can be ensured, so in the case of a ground with normal bearing capacity, it can be installed directly on the ground or on a crushed stone foundation.

A box culvert can be laid on a foundation as simple as waste concrete. Furthermore, in soft ground with low bearing capacity, it is possible to reduce the number of piles 14 in the pile foundation and adopt an independent foundation type as shown in FIG. 7. Therefore, construction can be carried out economically and quickly, and it can be used even at sites where precasting was previously thought to be impossible from the viewpoint of economy and structural function.

〔Effect of the invention〕

As shown in the above, the box culvert of the present invention has a concavo-convex portion with a fitting relationship formed on the end face, so it can significantly improve shear strength with a simple structure and prevent the occurrence of misalignment. By introducing prestress into this box culvert, complete integration can be achieved. At this time, since the stress generated by the elastic material sandwiched between the end faces is smoothly dispersed, it is possible to prevent bearing pressure failure or local shear failure due to the finishing accuracy of the end face.

[Brief explanation of the drawing]

Figure 1 is a front view of the box culvert of this embodiment, Figure 2
The figure is a side view, FIG. 3 is a plan view, FIG. 4 is an enlarged view of the fitting part, FIG. The figure is a side view to explain partial tension, Figure 7 is a side view to explain the pile foundation situation when this method is used, and Figure 8 is a cross section of the bottom plate showing the joint of a conventional box culvert. It is a diagram. 1. Bosculpart body 2 End face 3, convex part 4, other end face 5: Recessed part 6 Tapered surface 7. Insertion hole 8 Elastic body 9: PC steel material 10 Notch part 10a Anchor 11 Ground surface 12, Discarded concrete 13: Mortar 14. Piles □ Patent applicant Mizutani Construction Co., Ltd. Agent Masu Kobori Figure 7 Figure 8

Claims (1)

[Claims] 1. A plurality of trapezoidal convex portions having a tapered surface are formed on one end surface of the box culvert body, and a recessed portion that can fit with the convex portions is formed on the other end surface, and the box culvert body A box culvert, characterized in that a plurality of insertion holes are provided for inserting prestressing steel materials in the longitudinal direction, and an elastic material is attached to one end surface of the box culvert. 2. When consecutively laying the box culverts according to claim 1, after laying the box culvert on excavated and leveled ground, when laying the next box culvert adjacent to this, The concave or convex portions of the box culvert that will be laid later are interlocked with the convex or concave portions formed on the box culvert, and then the tensioning PC steel material is inserted into the insertion hole provided in the longitudinal direction of the box culvert body. Insert
A construction method that integrates the extension direction of box culverts, which is characterized by the introduction of prestress.