Luo R.-H.,China Railway Major Bridge Engineering Group Co.
Bridge Construction | Year: 2014
The main bridge of Yingwuzhou Changjiang River Bridge in Wuhan is a three-tower suspension bridge with span arrangement (200+2×850+200) m. The foundation for the north anchorage of the bridge is the gravity caisson foundation of "holed ring+crisscross partition walls". The external diameter of the caisson is 66 m and the height is 43 m. The foundation for the Tower No.1 is comprised of 44 nos. of φ2.0 m bored piles, for the Tower No.2 is of 39 nos. of φ2.8 m bored piles and for the Tower No.3 is of 20 nos. of φ2.8 m bored piles. The foundation for the south anchorage is the kind of the foundation of "circular rock-socketed diaphragm wall+lining". The diaphragm wall is the reinforced concrete structure, the external diameter of the wall is 68 m and the thickness is 1.5 m. In the light of the characteristics of the foundation works of the bridge, the caisson for the north anchorage was constructed by the caisson height extending and caisson sinking in 3 times. The pile foundation for the Tower No.1 was constructed by the scheme of artificial island and by the double-row protection bored piles. The foundation for the Tower No.2 was constructed by the scheme of constructing the steel cofferdam first and the working platform late, in which the cofferdam was launched to the river by the air bag method in integrity. The foundation for the Tower No.3 was constructed by the scheme of constructing the working platform first and the cofferdam late and by the single-row protection bored piles and the diaphragm wall for the south anchorage was constructed by the scheme of hydraulic trench cutter aided by percussion boring. ©, 2014, Bridge Construction. All right reserved.
Wang D.-H.,China Railway Major Bridge Engineering Group Co.
Bridge Construction | Year: 2016
The non-navigable span approach bridge of the Pingtan Straits Rail-cum-Road Bridge over the shallow water area (the water depth being less than 15 m) is a 48-m span prestressed concrete girder bridge. The foundations for the bridge are the bored piles that were constructed, using the cofferdams. A cofferdam for the construction of the piles is the steel boxed cofferdam structure that has the plan dimensions of 14.8×23 m and the height of 12.3 m and in the cofferdam, two tiers of the internal supports were arranged. Through the calculation of the load cases of anti-buoying of the cofferdam by pumping out the water and anti-sinking of the cofferdam after casting the concrete for the pile cap under the condition of base sealing of the cofferdam, it was determined that the depth of the base sealing concrete for the cofferdam should be 2 m. With reference to the sea condition characteristic of the Pingtan Straits and in thorough consideration of the wave force action and the great tidal difference influence, the cofferdam was integrally assembled and was integrally lowered to its designed elevation, using the jacks after the bored piles were constructed. In the cofferdam, 3 tiers of the guiding and limiting devices were also arranged in order to ensure the safety of the cofferdam at the time the cofferdam was being lowered into the water. After the base for the cofferdam was sealed and the water in the cofferdam was pumped out, the slinging system of the cofferdam was installed for the second time, the hangers and slinging corbels were installed again in order to accommodate the construction of the pile cap. The side plates and bottom plate of the cofferdam were connected by pins and the diagonal struts were welded to fix the side plates and bottom plate in order to resist the vibration caused by the wave forces. © 2016, Journal Press, China Railway Bridge Science. All right reserved.
Tao J.-S.,China Railway Major Bridge Engineering Group Co.
Bridge Construction | Year: 2016
The main bridge of the Qingshan Changjiang River Highway Bridge in Wuhan is a cable-stayed bridge with double pylons, double cable planes and with span arrangement (350+938+350) m. The foundation for the pylon pier No. 20 of the bridge is comprised of 60 nos. of φ2.5 m bored piles and was constructed, using the semi-floating dumbbell-shape double-wall steel cofferdam. The length of the cofferdam is 103.8 m, the diameter of the part of a cylinder is 43.4 m, the total height of the cofferdam is 37 m and the wall thickness is 2 m. Vertically, the cofferdam is divided into 3 parts of the bottom lift, middle lift and top lift, of which the height of the bottom lift is 18.2 m. The bottom lift of the cofferdam was manufactured in the shipyard and was assembled and welded into an integrity on the horizontal building berth also there. By the aid of 44 sets of the rail trolleys, the lift of the cofferdam was shifted from its assembling place to the support changing area of the wedge type launching cradles and was synchronously jacked up apart from its existing steel stands by the jacks on the rail trolleys to start the horizontal transverse shifting. After the supports of the lift of the cofferdam were changed at the comb type building berth, the lift of the cofferdam was then carried by 13 sets of the wedge type launching cradles, was synchronously slid down along the slope slipway and was finally steadily launched to the river and floated there. © 2016, Journal Press, China Railway Bridge Science. All right reserved.
Li L.-S.,China Railway Major Bridge Engineering Group Co.
Bridge Construction | Year: 2016
The main bridge of the Qingshan Changjiang River Highway Bridge in Wuhan is a cable-stayed bridge with double pylons, double cable planes and with span arrangement (350+938+350) m. The foundation for the main pier No. 19 of the bridge is the one that is comprised of 60 nos. of the variable diameter bored piles (the diameters of the upper 25 m of the piles being 3.0 m while those of the lower 67 m being 2.5 m) and the length of the piles is 92 m. In comprehensive consideration of the various factors of the topography, hydrology, geology and construction time schedule in connection with the construction of the piles, it was determined that the piles should be constructed, using the scheme of the “hydraulic reclamation island platform+rotary boring machine”. The reclamation island platform (the plan dimensions of the platform being 118 m×71 m) was used as the boring construction platform and the construction over the river was thus transformed to that on the land. After the reclamation island platform was well constructed, the steel casings for the piles were inserted and driven, using the resonance-free electrical vibration hammer aided by the 500 t caterpillar crane. The holes of the piles were bored by the large rotary boring machine, the high-quality slurry and circulating system were provided in the boring and the bored holes were cleared by the air-lifting reverse circulation. When the holes were cleared off, the reinforcement cages (a cage being 93.7 m long and being fabricated on the jig by the method of the long line match and a few joints) were lowered into the holes, the C40 tremie concrete was cast through the tremie ducts and at this stage, the construction of the bored piles was completed. The ultrasonic inspection of the completed piles of the main pier No. 19 proved that the shafts of the piles were all up to the Class I piles. © 2016, Journal Press, China Railway Bridge Science. All right reserved.
Liu Y.-H.,China Railway Major Bridge Engineering Group Co.
Bridge Construction | Year: 2015
The non-navigable span bridge of Contract CB05 of the Hong Kong-Zhuhai-Macao Bridge is a 85-m span steel and concrete continuous composite girder bridge. The foundations for the piers of the bridge are the ones of steel pipe composite piles. At each pier, 6 composite piles are provided and there are totally 372 piles for the whole bridge. In the light of the structural features and construction difficulties of the bridge, the construction schemes of a common boring platform of the "steel pipe piles+sectional steels" structure (Scheme 1) and an integral boring platform of the "integral steel truss type" structure (Scheme 2) were proposed for construction of the foundations. Through comparison of those aspects of the civilization construction, safety, environment protection, construction efficiency and construction cost, it was determined that the Scheme 2 should be selected. For the Scheme 2, the components of the boring platform were all fabricated in workshop following the standardization requirements and were welded into the integral steel truss structure. The steel truss structure was then transported by ship to the pier site where the structure would be installed or integrally removed for repeated usage at other pier sites by floating crane and at this stage, the construction of the boring platform was completed. The selected Scheme 2 can effectively shorten the time interval of shifting the platform from pier site to pier site and has advantages of high efficiency, safety, environment protection, energy saving and fast speed. ©, 2015, Wuhan Bridge Research Institute. All right reserved.