On April 18, Guangdong Communications Group announced that on the evening of the 17th, after the load test of 136 large trucks with a total weight of about 5,000 tons, the Lingdingyang Bridge of Shenzhong Channel completed the dynamic and static load test, which is the world's first load test completed on a super-large span suspension bridge in the whole offshore sea.
Previously, the load test of Zhongshan Bridge and non-navigable hole approach bridge of Shenzhong Passage has been completed. The bridge project of the Shenzhen-Zhongshan Corridor successfully passed the "big test", and it is a key step towards having the conditions for opening to traffic in June this year.
Lingdingyang Bridge load test site of Shenzhong Passage (photo by Shen Zhong)
136 heavy trucks were crushed
A comprehensive physical examination for the bridge of the Shenzhen-Zhongshan Channel
The Shenzhen-Zhongshan Corridor is a world-class "bridge, island, tunnel and underwater interconnection" cross-sea cluster project, with a total length of about 24 kilometers. Among them, the total length of the bridge project is about 17 kilometers, including Lingdingyang Bridge (suspension bridge), Zhongshan Bridge (cable-stayed bridge) and non-navigable hole approach bridge.
The load test is a "whole body physical examination" before the bridge is opened to traffic, which is divided into static load test and dynamic load test. By simulating the load after the opening of traffic, the reaction data of each part of the bridge is tested on the spot, and whether the bearing capacity of the bridge meets the design requirements and relevant specifications, so as to provide the original data for delivery and acceptance, and also provide scientific basis and support for future maintenance and management decisions.
In order to scientifically evaluate the impact of tens of thousands of vehicles passing through the bridge every day, we calculated through the influence line method, and arranged 9 to 136 test vehicles in a variety of loading conditions, arranged in the most unfavorable position of the bridge deck, and tested the internal force, displacement and stress of the bridge structure on the spot, and comprehensively evaluated the working performance of the bridge. Chen Huanyong, engineer of the Shenzhong Channel Management Center of Guangdong Communications Group, introduced.
Lingdingyang Bridge load test site of Shenzhong Passage (photo by Shen Zhong)
In order to minimize the influence of interference factors, the load test was carried out between 21:00 and 6:00 the next morning when the wind was low, the temperature was constant, and there were few temporary vehicles.
The maximum loading condition in the static load test of Lingdingyang Bridge is that 136 large trucks with a total weight of about 5,000 tons are loaded on the bridge in batches, and 17 rows × 8 columns of squares are parked at the pre-demarcated stops on the bridge deck for graded loading. Engineers measure the displacement and strain of the main girders, towers, cables, and slings and compare them with theoretical values to evaluate the working performance of the bridge.
In the dynamic load barrier-free driving test, engineers arranged for two trucks with a total load of 70 tons, equivalent to the weight of about 45 cars, to drive on the bridge at a constant speed ranging from 10 to 60 kilometers per hour. Using the sensors, engineers test the dynamic response of the structure under driving loads and analyze the impact coefficient of the bridge.
The bridge is equipped with a "CT" machine
Multiple verifications ensure accurate data
The Lingdingyang Bridge of Shenzhong Passage is a three-span steel box girder suspension bridge with a main span of 1666 meters, which affects each other and is highly sensitive to temperature changes.
In order to ensure more accurate test results, the project load test uses multiple means to verify each other, and for the first time, a health monitoring system is introduced as a reference. "In the displacement test of the main beam, we used three systems at the same time: total station, connecting tube and series-parallel camera for data acquisition, analysis and comparison. The system is fast and accurate to the millimeter, allowing for better validation. Chen Huanyong, who comprehensively compared the data on the spot, explained that similar to the CT machine used in human physical examination, by taking the above-mentioned comprehensive measurement measures, collecting and analyzing images, calculating the relative displacement data of the camera and the target, and reflecting the displacement of the bridge structure in real time and dynamically.
Lingdingyang Bridge load test site of Shenzhong Passage (photo by Shen Zhong)
"Judging from the data currently available, the measured values of the Lingdingyang Bridge, Zhongshan Bridge and non-navigable hole approach bridge of the Shenzhen-Zhongshan Channel are all smaller than the theoretical values, and most of the indicators are surplus. This means that the bridge project of the Shenzhen-Zhongshan Corridor has not only passed the 'physical examination', but can also be said to have achieved good results in the 'physical fitness test'. Yao Zhi'an, deputy director of the Shenzhen-Zhongshan Channel Management Center of Guangdong Communications Group, said.
At present, the electromechanical, traffic safety, pavement, housing construction and other ancillary projects of the Shenzhen-Zhongshan Corridor are in full swing to sprint for the opening of traffic in June. After the completion and opening of the project, the driving time between Shenzhen and Zhongshan will be greatly shortened from the current about 2 hours to 30 minutes.
Reporter / Liu Weitong