[关键词]
[摘要]
红旗渠曙光渡槽多年运行后出现不同程度破损,存在一定安全隐患。基于ABAQUS软件,建立渡槽三维有限元计算模型,采用均质化理论对三维渡槽结构模型进行静力计算,分析渡槽结构的应力和位移,复核渡槽基础沉降,同时考虑差异荷载及温度荷载对渡槽结构的影响,综合评价该渡槽的结构安全。研究结果表明:各槽墩压应力最大值主要分布在墩台和槽墩的接触部位,拉应力最大值均出现在槽墩墩台底部,最大压应力和拉应力分别为2.90 MPa和2.29 MPa,槽墩局部范围出现应力集中;槽墩最大沉降值为1.57 mm,各相邻墩台沉降差最大值为1.07 mm,差异荷载造成的应力集中与温度荷载叠加效应会对槽墩中部产生一定影响。综合认定该渡槽结构安全为B级。
[Key word]
[Abstract]
To solve the problem of uneven distribution of water resources,numerous interbasin water transfer projects have been built in China,including a great number of large aqueducts.After decades of operation,the aqueduct structure is prone to aging and damage,which has certain potential safety hazards.Shuguang aqueduct is one of the important buildings of the third main channel of the Red Flag Canal.The aqueduct has a total length of 550.0 m,a maximum height of 16.0 m,a bottom width of 5.4 m,and a top width of 3.5 m.The aqueduct is a masonry aqueduct,and its main buildings include upstream approach canal,aqueduct body,arch structure,main arch ring,pier and abutment,and downstream approach canal.After more than 50 years' operation,the on-site inspection found that the jointing materials between masonry were aged and weathered,and the upper structure of the upstream approach canal,aqueduct,and downstream approach canal or trough body,especially the mortar in the top area,was seriously out of joint,which deserved attention.Based on ABAQUS software and homogenization theory,a three-dimensional finite element calculation model of the aqueduct was established to calculate the stress,deformation,and foundation settlement distribution of the whole structure of the aqueduct under different working conditions.Furthermore,the influence of differential load and temperature load on the aqueduct structure was presented.Finally,the structural safety of the aqueduct was comprehensively evaluated. Under different load conditions,the maximum compressive stress of each pier of the Shuguang aqueduct was mainly distributed at the contact position between abutment and pier.The maximum tensile stress of each pier appeared at the bottom of the abutment of the pier.The maximum compressive stress and tensile stress were 2.90 MPa and 2.29 MPa,respectively.The tensile stress of the pier exceeded the tensile strength of the masonry cementitious material but only occurred in a small local area.However,when the temperature dropped,the pier was greatly affected by tensile force,and the tensile stress in the middle of the pier and the bottom of the pier exceeded the tensile strength of masonry cementitious material,which had a great influence on the structure of the pier.Under the action of static load,the transverse displacement of the aqueduct was mainly located in the middle of the aqueduct,the longitudinal displacement was mainly distributed at both ends of the aqueduct structure.The settlement of the aqueduct was mainly located on the leeward side of the pier and abutment.The maximum settlement of pier foundation and settlement difference of adjacent pier foundation under each working condition appeared in Condition 6,with the maximum settlement value of 1.57 mm and the maximum settlement difference of 1.07 mm.The settlement difference of the aqueduct and adjacent pier was less than the allowable value of 100 mm and 50 mm,respectively,which can meet the requirements.The differential load and temperature load on the aqueduct pier would cause horizontal tensile stress in the middle of the pier,which caused longitudinal cracks.The sudden drop in air temperature induce surface temperature cracks in the aqueduct pier,but it did not affect the deep part of the pier structure.Two suggestions were proposed,including strengthening deformation monitoring in the middle of the pier and repairing the surface cracks. Through comprehensive analysis,it indicated that the structural safety of the aqueduct was recognized as Class B.The research methods and achievements can provide a reference for structural stress and deformation analysis and safety evaluation of similar aqueduct projects.
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