Analysis Of Vehicle Bump At Bridge Head And Study On Influencing Factors Of Settlement Control

Kunshan City is in the eastern part of the Yangtze River Delta.The soft soil in the area is dominated by lake and lake deposits.The silt soft soil is widely distributed,thick and easy to compress.With the increasing traffic volume,the bearing capacity of the old roadbed can't meet the requirements,and the treatment technology of the new roadbed lacks scientific guidance,so that the roads in Kunshan City generally suffer from bridgehead bounce disease.It is urgent to carry out the mechanism analysis and control measures of the abutment bumping diseases in Kunshan City to provide an important reference for the actual projectBased on summarizing the research results of domestic and foreign bridgehead jumping theory analysis,treatment measures,process improvement,etc.,combined with the geological conditions of Kunshan City,this paper investigates the current status of road and abutment bumping diseases in service.There are mainly pavement ladder settlements,pavement depressions,pavement cracks,staggered shoulders,and guardrail cracks.Based on the research background of the third bid section of Yuanfeng Avenue,a typical completed project,combined with the treatment technology of the bridgehead section,hydrogeological conditions and on-site investigations,the cause of vehicle bumping at the bridge approach of the newly built road is analyzed.The results show that the main causes of car jumping on Yuanfeng Avenue are:the foundation changes along the way,and the settlement after construction is inconsistent;the fill under the slab is hollowed out,the soft soil settlement is uneven,and the thickness of the slab is insufficient,resulting in the slab fracture;limited by the abutment,the compaction of lime soil behind the platform is not up to standard;the preliminary survey is insufficient,and the roadbed behind the platform has a quicksand layer,which leads to an increase in the settlement of the roadbedIn addition,relying on the Yushan-Zhangpu section of Provincial Highway 224 of the old road reconstruction project.Deploying points to monitor the post-construction settlement and the development of cracks in the bridge head section,combined with geological conditions and treatment techniques to accurately track the cause of vehicle jumping.The results showed that the 224 Provincial Highway caused vehicle jumping disease due to differences in road and bridge stiffness,deep soft soil layers,design defects,and process inversions.At the same time,there were also problems such as improper preloading treatment,rainwater leakage from expansion joints,and other problems of increased settlement.Finally,for the 312 national highway project that is planning to be built,PLAXIS finite element software is used to establish a typical bridge head section model.The original plan model is first established,and the rationality of the model is determined by comparing the settlement data with the specification.Further change the pile layout mode,the preloaded preloading mode and the transition step mode to obtain the subgrade settlement cloud map,and compare the model settlement data under a single variable to obtain the optimized scheme.The results show that the optimal spacing between square piles is 2.6m and the plum blossom shape is 2.8m;equal-load drainage preloading and overloading drainage preloading can greatly shorten the preloading time while ensuring the treatment effect;the bridge head section transition steps are reasonable.The setting can effectively solve the problem of uneven settlement in the transition section.For the Qingyang Port road project that is planning to be expanded,PLAXIS software is used to simulate the settlement cloud map of the lightweight concrete and lime soil in backfilling subgrade.The results show that compared with the lime soil subgrade,the weight of lightweight concrete is lighter and it can reduce settlement more effectively.