Highway bridge expansion joints and bridge design specifications junction bridge joints in order to reduce the occurrence of jumping, must develop detailed construction standards for road and bridge construction. Accordance with the "Design and Construction of Highway Embankment technical specifications" of standards, regulations and permitting subsidence highway after highway built for: ordinary road no more than 30cm, embankment and bridge abutment connection is not more than 10cm. Early in the design should be detailed reconnaissance geological conditions under the bridge foundations, abutments provided on the basis of soil bearing capacity, by broadening the base of the foundation pile or fabric for reinforcement, which can significantly reduce the amount of embankment subsidence. However, due to the foundation side after filling station segment is not as reinforcement, easily lead to soil base consolidation compression, causing subsidence differences. According to the survey, when the highway was wrong at the time of NTU 1.5cm, it may lead to jumping. So must carefully analyze the differences between the two, try to avoid jumping occurs at the junction. Repair of roads and bridges designed bridge expansion joints at the junction of Bridge jumping phenomenon has occurred for road, you want to make the repair design. Repair of roads and bridges construction, though not change the overall design, but by means of a certain construction, such as the backfill material, backfill compaction way station, station construction methods backfill handling design and selection, can effectively improve the subgrade stiffness, reducing the roadbed sink, reducing the incidence of bridge jumping. Therefore, the relevant departments should strengthen the repair of construction design concern, the effect has been to achieve the best repair. In the current project, grouting reinforced concrete back filling fast repair technique is a common road and bridge repair technology, which is the use of cement and polymer slurry stirred formation ways not only simple, but also can effectively subgrade foundation bearing capacity and strengthen the abutment at. Bump 50 ~ 70m away from the bridge at the beginning of every 1.5 ~ 2.0m, marked diameter 7.5cm, depth ranging from 10 ~ 25m Plum type hole, and then the slurry is injected into the hole, so you can enhance the soil, increasing foundation bearing force, Plum hole size, depth and spacing should be designed according to the actual settlement and exploration results pavement. 3. The design of bridge expansion joints bridge expansion joints 3.1 functionality and variety of joints (also known as the bridge expansion) includes displacement control system and force support system, through the support structure of the vehicle to achieve horizontal and vertical load transfer to the beam of , and can adapt to the bridge beam end warping angle changes, and vertical and horizontal displacement. Joints based on the use of different materials and can be divided into: composition, plate, pure style and modulus of rubber expansion joints. Modular expansion joints made of steel pallets and rubber plates, can be used to stretch the amount of ordinary ≤120mm bridge; plate made of rubber expansion joints, angles or steel plates can be used for expansion joints <60mm of ordinary bridge; Modular components more , according to some arbitrary group fight modulus, widely used in a variety of wide, oblique, sloping, curved bridge. Factors that affect the joints highway bridge expansion joints designed to influence the design of the bridge expansion joints including the location of the bridge, structure and load rating, the flatness of expansion joints, the scope of waterproofing and structural characteristics of the economy and expansion joints maintainability, and quality control measures in the construction environment. The basic factors affecting the amount of stretching highway bridge expansion joints (1) vertical slope. When the displacement of bridge bearings, expansion joints occur level of its displacement and vertical displacement, multiplied by the size of longitudinal horizontal displacement value. (2) concrete creep and shrinkage of concrete creep and shrinkage is a random phenomenon, is a property of the concrete itself. Creep and shrinkage of concrete affected by temperature, cement type, water-cement ratio, relative humidity, slump, mix and concrete strength, age and duration of load factors greater impact. For prestressed and reinforced concrete bridge, to consider the creep and shrinkage. Joints have occurred during the installation of creep and shrinkage, it must start to follow the installation start time, in order to subtract concrete creep and shrinkage. (3) Rao degrees. Bridges affected by various loads will cause the ends of angle change occurs, leading to expansion joints occur horizontal, vertical and angular displacement, when the beam is high also lead to shock. (4) temperature. Changes in the amount of the main factors bridge stretching from the temperature, temperature changes, including linear and non-linear, in which the main factors affecting the amount of stretching is linear temperature changes. Under certain conditions of ambient temperature, the internal temperature of the bridge will be unevenly distributed, due to changes in the thermal properties of the material can cause the ends of the beam is angularly displaced. General L≤8m span bridge, its linear expansion coefficient is negligible; but in the long-span bridge design temperature effects must be considered. (5) earthquake. Affected by the earthquake telescopic device is not yet clear when the earthquake on the level of the bridge pier moving, rotating, tilting and subsidence can be calculated, should try to join consideration. 

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