The highway bridge widened technology research
Shandong Oriental bridge construction corporation, shandong linyi
Along with the development of the cause of China's transportation, highway traffic growth, some highway original rank oneself can not meet the requirement of use, because this wants to have widened transformation. Therefore, we need to make full use of the original bridge for the widening, this paper summarized the domestic main bridge of widening idea, method, classification and characteristics, the thorough research of the design of the system and widen bridge construction method respectively, the precast concrete box girders, pre-cast hollow slab bridge several characteristic were analyzed, and the uneven subsidence analyzed the influence of the bridge widened, according to the bridge technique conditions, conclude and put forward reasonable targeted measures to widen.
Keywords: bridge widened stitching technique, the uneven settlement influence, not even on even mode, the design scheme
1. The introduction
Along with the social economy into the fast lane development, in order to meet the needs of economic development, the countries each year spending a large amount of money to new many road, such as the 2003 annual new highway 63000 kilometers, among which, highway 4952 kilometers. But, just rely on new roads, and cannot effectively relieve the problem of shortage of highway capacity. Because of this country in the new roads, but also to develop the expansion of original highway, in order to improve its capacity, meet the needs of the transportation. Highway expansion project, often need in the original highway both sides or one side of widened, this involves the original highway bridge expansion of problems. Generally speaking, the highway expansion often make original highway bridge load on the standard improve, the need to reinforce and expand the original bridge, that brings us broaden the joining together of the structure of the new and old bridge linking problem.
Based on the collection of reconstruction projects in both of the evaluation of the bridge and widened technical aspects of the relevant information, on our country's existing bridge basic condition investigation and analysis and so on many kinds of analysis method of research work. This paper on the highway bridge the theory of both widened to summarize, based on some examples make calculation analysis, according to the calculated results of the analysis of the reconstruction projects widened bridge construction proposals put forward.
2. The type of connection bridge widened
The new and old structures bridge widen the connection between the way is the main factor of the bridge widened success or failure, from the domestic has succeeded the highway bridge widened connection mode, can provide three ways to choose from:
1. Are not even up and down the spell wide mode
New and old bridge between the lower and upper structure between structure are not connected. No connection between the top and bottom structure, only in. The new and old bridge is a seam between work, then bridge asphalt concrete pavement for paving. The connection to the new and old bridge is clear, no influence their stress, simplified the construction procedures, avoid connection of the technical problems.
2. All of the connection and spell wide mode
New and old bridge between the upper structure and the supporting structure are connection between. The new and old bridge is the upper correspondence between horizontal position through the plant steel casting wet juncture, connecting the corresponding pier hat, the department also plant steel beam through connection, then placement to form the whole. The connection to the new and old bridge is form the whole, a smaller load both joint distortion.
3. The upper connection not connect the spell wide mode
New and old bridge connection between the upper structure, the supporting structure between the connection, a combination of these two connections and the advantages and disadvantages of the way, can the comprehensive up new, old bridge is the upper connection, and at the bottom not connect the modes of the connection. This way is new and old Bridges foundation separation, the upper plate beam structure are connected. Cut the old bridge concrete beam pick arm, preserve the steel bar and reinforced or planting new bridge hinged or just answer. Pouring wet juncture and laid bridge deck pavement reinforced continuous and encryption, form the upper deck of the continuous structure.
Through above three widened form of contrast, not even on even the bridge widened joining together in engineering application way a broader, this scheme is more suitable for settlement of new old bridge is influencing the region, this paper mainly on not to even even this widening joining together the way.
3. The highway bridge widened joining together design research
3.1 hollow slab bridge widened joining together implementation plan
3.1.1 widened section
The hollow slab of original structure according to widen type joining together. Due to the highway hollow slab board, prefabricated wide and high cantilever etc feet. "there is some difference. First a 20 m board, 16 m board recently built than early built high 10 cm respectively, 5 cm, the rest of the composite board the same high. The original bridge half width have and two, after half range have widened bridge 20.25 m and 20.49 m two width.
3.1.1&3.1.2 joining together plan: wet juncture connection
The original bridge between bridge and widened by cast-in-situ concrete will be connected to the wet juncture overall, in the hollow plate at each end set a 50 CM beam, strengthen its integrity. Widening bridge set up months, then wet juncture connection, reduce shrinkage and creep and the influence of the base settlement.
Wet juncture wide, respectively, in 25, 37.5, 50 cm.
3.1.3 pruning the implementation steps
A. demolished the original bridge outside the guardrail, chiseled in bridge deck pavement dismantled as shown in figure a scope, the original bridge outside side boards are cantilever, need to the cantilever resection.
B. the original bridge cantilever plate roots and steel roof implants.
C. installation widened bridge hollow slab, widened bridge deck hinge joints and cast-in-place layer construction.
D. four months later, half range closed, half of traffic, chiseled in closed the bridge deck pavement side.
E. transfer traffic, according to a procedure, construction of bridge and the other half wet juncture in joining together deck cast-in-situ layer and the road engineering and construction bridge asphalt concrete pavement.
Wet juncture connection 3.1.4 radar echoes captured characteristics
1. Good entirety and ensure that new new old structure overall stress together
2. Wet juncture joint DuDu just bigger, and in the board at the end of the set to strengthen beams, ensure sufficient strength to resist the enough for shrinkage and creep and base settlement from additional internal and deformation.
3. Avoid demolished the original department under the bridge.
4. The bridge deck is beautiful, after widened driving comfort.
5. Later maintenance costs low.
3.2 precast box girder bridge widened joining together implementation plan
Widened section 3.2.1
New widened precast concrete box girders of the original structure type joining together. 30 meters high beams are precast concrete box girders of 1.6 meters. The box of roadbed width of 24.5 m, width to widen roadbed after 41 meters.
3.2.2 joining together plan: concrete weak just answer
The concrete hinge transverse coupling, processing measures the bridge cantilever is the cutting off by the regulation, hair cut in the concrete surface, the specified position in plant steel and besmear interface glue, widening embedded steel and plant steel welding, casting steel fiber express hard shrinkage-compensating concrete form wet juncture.
3.2.3 weak rigid connection meet features:
The scheme has advantages:
1. Good entirety and ensure that new JiuTi joint force.
2. The bridge deck is beautiful, driving after widening convenience.
3. Later maintenance cost is low.
Main shortcoming for connection, widen the bridge and the original bridge produce born the uneven settlement, to widen the bridge and the original bridge great influence, to the uneven settlement request is higher.
4. Bridge widened the main design engineering research
According to the preceding chapters discuss plans by the analysis, we can see that the foundation of relative settlement control in a range is an important technology of the relationship between the quality of joining together.
Through the calculation examples of bridge settlement, found that usually happens when the foundation uneven subsidence, settlement produced by the horizontal part of tensile stress the same basic. This is because the meters across a hollow slab structure stress simple, so when basic settling, structure brings its own the most unfavorable effects occur in new old bridge is connected areas, in this case, the old bridge is part of the new bridge and ground seam will happen craze, so in view of the above may appear, put forward the following Suggestions:
1. The new bridge in widening the design, the construction process, the foundation design whether meet the requirements and construction quality stand or fall of xinqiao partial foundation must be in the size of the settlement has the most direct impact, so in the foundation design process, must be carefully in the textual research in geological conditions, choose appropriate pile diameter, the pile length. The construction process of strict control construction quality.
2. Such widened the bridge, xinqiao base settlement of the influence of inevitable, so for the new old bridge is connections must adopt corresponding measures, such as bearings in the settlement of new old bridge is connection plate should be implanted into a lot of reinforced to combat support when the lateral stress produced settlement in connection to other parts of the board should also be implanted into a certain amount of reinforced add new old bridge is integrity, will base settlement caused by ignore influence to the minimum.
3. In widening the construction process, must be the original hollow slab of ground sew to replace, xinqiao hollow slab in construction process should also ensure that ground seam quality of construction, thus make the load in the bridge of the lateral evenly transfer, improve the integrity of the whole bridge.
5. Research conclusion
Bridge widened joining together project is a more complicated engineering. As China's economic construction and the development of the cause of the highway bridge, such project will more and more on in front of us, how in safe, beautiful, economy, the principle of applicable to widen bridge reconstruction work, the builders of the bridge before an important issue.
Expansion of bridge reinforcement and new matching, including several aspects. So in both Bridges to evaluate and after checking, can take corresponding measures to rebuilding both Bridges. This project on domestic several typical splicing scheme in the summary, puts forward the joining together of bridge, implementation method and construction scheme and the matters needing attention of typical bridge the joining together calculation, for the next stage of the work provides reference. At the same time the project on the concept of bridge reinforcement, the goal and the basic requirements has summarized, and to all the problems both Bridges targeted brings forward the reinforcement method.
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