JPS6114303A - Road widening method and hollow prestressed concrete plate used therein - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a road widening method and a hollow prestressed concrete plate used therein.

BACKGROUND OF THE INVENTION The present applicant has disclosed an invention described in Japanese Unexamined Patent Publication No. 71904/1983 as a road widening method using a tensioning method.

In this invention, an overhanging girder is mounted with a part of it overhanging the widening side end of the existing road by being supported on a support platform cast at the widening side end of the existing road, and the mountain side end of the overhanging girder is used for reaction force. It is fixed with anchors, and the floor slab is placed on the overhanging girder via a longitudinal girder in the direction of road travel.

The projecting and widening road has the advantage that it does not require the labor of cutting and filling soil during construction, and also has the extremely large effect of providing a stable structure due to the support piles and anchors.

Problems to be Solved by the Invention The problem with the above-mentioned construction method is that the work is laborious and takes a long time, which significantly impedes road traffic.

In other words, the longer the construction time, the longer the road traffic will have to be stopped, and if the heights of the existing road and the new widened passageway are significantly different, additional construction work will have to be carried out to bridge the height gap between the two. As a result, the amount of time required for road traffic to stop has increased.

It is conceivable to use precast concrete plates to widen the road for this reason, but since they protrude far from the existing road, they must be highly strong.

Means for Solving the Problems The road widening method according to the present invention involves placing a hollow prestressed concrete plate on an existing road, making a part of it stick out, and supporting the hollow prestressed concrete plate with support piles. However, the above problem is solved by tensioning and fixing the reaction anchor to apply a downward prestress force to the mountain side end of the hollow prestressed concrete plate.

Furthermore, the hollow prestressed concrete plate according to the present invention is manufactured by using a cement mixture obtained by adding water to a mixture of 50 parts by weight of cement and adding 50 parts by weight or less of siliceous powder to make a total of 100 parts by weight. This solves the above problems.

EXAMPLE The present invention will be described in detail below based on an example shown in the drawings.

(1) Support pile driving Support piles 1 are driven at predetermined intervals along the widening side edge of the existing road. As the support pile 1, a PC pile or the like can be used, and a known driving method can be used by using an earth auger or the like.

A pedestal 2 is placed on the support pile 1.

(2) Installation of reaction force anchors Reaction anchors 4 are installed at predetermined intervals corresponding to the support piles 1 along the mountain side edge of the existing road. ′
First, a hole 5 is formed in the ground, and a prestressed steel material 6 is inserted. P
The lower half of the C steel material 6 is fixed in the drilled hole 5 by injecting a grouting material 7, and the upper end is made to protrude above the ground surface.

A leveling girder 8 made of H steel or the like is installed on the ground surface adjacent to the drilled hole 5 in parallel to the road traveling direction.

(3) Leveling of existing roads Leveling mortar, leveling concrete, etc.9 on the surface of existing roads
has been poured. It is also possible to level the surface using dry mortar, dry concrete, or hardening powder.

(4) Hollow Prestressed Concrete Plate In this invention, a hollow prestressed concrete board 10 is particularly used.

The hollow prestressed concrete plate 10 is a precast concrete plate produced in a factory, and has a hollow portion 11 penetrated in the width direction. A plurality of hollow portions 11 are formed at appropriate intervals in the longitudinal direction. A PC steel material is buried in the hollow prestressed concrete plate 10 in parallel with the hollow part 11 and is tensioned to apply a prestressing force.

Hollow prestressed concrete plate 1o is made of cement 50
A cement mixture is produced by adding water to a mixture in which 50 parts by weight or less of siliceous powder is added to 100 parts by weight or more, and kneading the mixture with water.

As the cement, ordinary, early strength, ultra early strength, or white Portland cement is generally used. Additionally, mixed cement mixed with blast furnace slag and expanded cement can also be used.

The siliceous powder is preferably silica dust (silica fume) or siliceous dust produced as a by-product during the production of silicon, silicon-containing alloys, and zirconia.Fly ash 1. Contains a lot of 810, including sandstone, silicate clay, volcanic ash, diatomaceous earth, fired clay, etc., and is highly active and C.
It is a powder of a phoson substance that easily combines with a (OH). The amount of siliceous powder used in the present invention is based on 100 parts by weight of the mixture (cement + siliceous material).
At most 50 parts by weight in 10% of the inside, preferably 4 parts by weight inside.
It is 0 to 2 parts by weight. If it exceeds 50 parts by weight on the inside, the strength will decrease, and if it is less than 2 parts by weight, the effect of the siliceous material will not be exhibited.

Next, in order to improve workability, it is advantageous to increase the water/mixture ratio, but the compressive strength is 1o o o K9
In order to obtain ultra-high strength of /cd1 or more, a water/mixture ratio of 0.35 or less is required, and a more preferable range is 0.35 or less.
20 to 0.30. It is also possible to add a high performance water reducing agent to improve workability. A high-performance water reducing agent is a surfactant that has a high dispersion ability without causing too much delay in setting or excessive air entrainment even when added in large quantities.
Specific examples include salts of melamine sulfonic acid formaldehyde condensates, salts of naphthalene sulfonic acid formaldehyde condensates, high molecular weight lignin sulfonates, polycarboxylate salts, and the like as main components. The amount of high-performance water reducing agent to be used is 10 parts by weight or less, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the mixture. adversely affects curing.

As the aggregate, the usual aggregate used for mortar or concrete is used, but if even higher strength is required, any one with a Mohs hardness of 6 or more, preferably 7 or more, or a Knoop indenter hardness of 700 KP/m or more is used. It is preferable to use hard aggregate selected according to these criteria. The reason for setting the selection criteria for aggregate as described above is that the matrix of mortar and concrete hardened material (hereinafter referred to as "hardened material") is composed of cement hydrate, so the matrix strength is extremely high physical properties. However, if the hardened material is viewed as a composite of matrix and aggregate, fracture will occur from the weak parts, so if stress concentration is taken into account, if weak aggregate is used, the matrix strength will decrease. It is not possible to take advantage of this, and destruction occurs from the aggregate part. Therefore, not only the matrix strength but also the durability or strength of the aggregate is important.

Usable in the present invention that satisfies the above criteria
Examples of hard aggregates include sandstone, pyrite, hematite, magnetite, yellow jade, lawsonite, corundum, zenasite,
Spinel, beryl, full curb stone, tourmaline, granite, andalusite,
Examples include crossstone, zircon, calcined bauxite, boron carbide, tungsten carbide, ferrosilicon nitride, silicon nitride, fused silica, fused magnesia, and silicon carbide.

Further, it is generally desirable to use concrete as a composite material in combination with a reinforcing material, and it is preferable that the hollow prestressed concrete plate of the present invention is also reinforced with a reinforcing material.

As the reinforcing material, reinforcing bars and/or fibers are used. Rebar ores used in conventional concrete products are sufficient.

The long fibers are rovings, and the material used is at least one of inorganic fibers such as iron, carbon, and alkali-resistant glass, and organic synthetic fibers such as polyvinyl alcohol, polyester, and polypropylene.

The short fibers can also be made of the same material as the long fibers.

Next, the method for molding the cement mixture kneaded with the above composition is the usual pouring method, molding method using a vicon,
Pressure molding method, vacuum pressurization method, vacuum degassing method, centrifugal molding method, vibratory centrifugal molding method, etc. are used.

A method for curing the cement mixture formed by the above method will be explained.

The curing used in the present invention may be ordinary curing, but high-temperature and high-pressure curing, such as autoclaving and sealed mold curing, are shown as methods for obtaining high strength. The curing conditions are 2 ox5
i/c11 (214°C) or less is preferred, particularly preferably 6Kp/m (164°C) to 15Kp/d (
200°C). If it exceeds 20 Kf/m, the strength will not increase as desired due to the influence of high temperature and high pressure. In addition, when autoclave curing is used, pre-curing and steam curing are required, whereas when curing in a sealed form, pre-curing is not required and high-temperature and high-pressure curing can be performed immediately after pouring.

(5) Installation of prestressed concrete plate This hollow prestressed concrete plate 10 is placed on the existing road so that the hollow part 11 is perpendicular to the road traveling direction, and a part of the plate is extended toward the valley side. The widthwise middle of the hollow prestressed concrete plate 10 is placed on a pedestal 2 and supported by a support pile IK.

The mountain side end of the hollow prestressed concrete plate 10 is placed on the leveling girder 8.

The PC steel material 5 of the reaction anchor 4 is made to protrude onto the hollow prestressed concrete plate 10 and is tensioned by jacking. Then the bearing plate 120. It is fixed with a wedge or nut 13 in the hole. After fixing the reaction anchor 4, a grouting material 7 is injected into the upper part of the side hole 5.

As described above, the reaction anchor 4 applies a downward prestress force to the mountain side end of the hollow prestressed concrete plate 10.

(6) Other configurations It is also possible to use unbonded PC steel material as the reaction force anchor 4.

Function: Experimental examples of hollow prestressed concrete plates according to the present invention are shown below.

With the concrete mix shown in Table-1, φ10m x 20c1
A cylindrical specimen of n was prepared, preheated for 6 hours, and heated at a rate of 20°C.
After steam curing at a maximum temperature of 65° C./hr for 4 hr, autoclave curing at 10 KP/m (183° C.) for 10 hr, and a compression test at 28 days old, the results are also listed.

(Note) Each component in the table is as follows.

Cement: Ordinary Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Siliceous powder: Ferrosilicon by-product siliceous dust
Average particle size: 0.5 μ High performance water reducing agent: FT-”5oo manufactured by Denki Kagaku Kogyo Co., Ltd.
(Added in terms of active ingredients) Fine aggregate: Hard sandstone from Ome (specific gravity λ65, Mohs hardness approx. 6)
．． 51 particle size 51L11 or less) Coarse aggregate: Hard sandstone from Ome (specific gravity 2.65, soce hardness approx. 6.59 particle size 5 to 25 companies) With the formulation of Example 4 shown in Table 1, autoclave 28 of φ10cm×20α cylindrical specimen when curing conditions were changed
The results of the compressive strength test are shown in Table 2.

The pretreatment and steam curing were the same as in Example 4.・Night-2 Effects of the Invention Since this invention has the force structure described above, it is possible to obtain the following effects.

■ Since it is an overhanging method, there is no need for cutting or filling, which greatly reduces the amount of earthwork and shortens the construction period.

■ There is no need to cut the mountain side, so there is no damage to the existing slope. Therefore, there is no need to carry out new slope protection work.

■ Support piles will be installed at the end of the existing road, resulting in a more stable structure than one created by state-side land reclamation. There is also no need to worry about contaminating rivers, etc.

■ If a live load acts only on the overhanging part, the reaction force can be taken by the anchor installed at the mountain end, resulting in a stable structure.

■ Since hollow prestressed concrete plates are simply transported to the site and placed, the construction period can be shortened and the impact on road traffic can be minimized.

■Hollow prestressed concrete plates have hollow parts, are relatively lightweight, and are easy to transport.

■ Because hollow prestressed concrete plates are produced in factories, we can be confident in their quality, and even though they are relatively thin, they maintain a certain level of strength. There is no need to change the height significantly, there is little incidental work, and the impact on road traffic can be minimized.

■ The concrete block of the present invention has a compressive strength of 10
Since it has an ultra-high strength of 0.9/d or more, a large prestress can be introduced, making it ideal for use as an overhanging board for widening roads.

■ Ultra-high-strength concrete plates with excellent abrasion resistance are used for the road plates, making them extremely durable and highly reliable as public structures.

[Brief explanation of drawings]

Figure 1 is a perspective view of the widened road constructed according to this invention;
FIGS. 2 to 4 are longitudinal cross-sectional views of the construction sequence. 1. Support pile, 2. pedestal, 4. reaction anchor, 5.
・Drilling holes, 6.・PC steel material, 7.・Gouting material, 8.・Leveling girder, 9.・Leveling concrete, 10.・Hollow prestressed concrete plate, 11.・Hollow part, 12.・・Bearing plate, 13...Natsuto.

Claims (2)

[Claims] (1) Support piles are driven at predetermined intervals along the widening side of the existing road, reaction anchors are constructed at predetermined intervals on the mountain side, and support piles are installed on the existing road at right angles to the direction of road travel. A hollow prestressed concrete plate having a hollow part in the direction is placed, a part of which extends to the valley side from the existing road, the hollow prestressed concrete plate is supported by the support pile, and the reaction anchor is tensioned and fixed. A road widening construction method characterized by applying downward prestress force to the mountain side end of a hollow prestressed concrete plate. (2) For 50 parts by weight or more of cement, 5 parts by weight of siliceous powder
It is manufactured by adding water to a mixture made by adding 0 parts by weight or less to make a total of 100 parts by weight, and kneading the cement mixture, and having a hollow part penetrating in the width direction, and a prestress force applied in parallel to the hollow part. Hollow prestressed concrete plate given.