| As a kind of hydraulic structure,aqueduct is widely used in water transmission project,which plays an important role in maintaining water consumption for residents and transferring water across regions.With the increase of service life,the aqueduct suffers from the erosion of natural environment,and the aqueduct aging is increasingly serious.Its safety,reliability and durability decline year by year with time.Therefore,it is urgent to evaluate the structural safety of the aqueduct whose structure is aging in the 1970 s and 1980 s.This paper takes Shangwu aqueduct of Yiwu City as an example to scientifically evaluate the structural safety of existing aqueducts in China,which can effectively avoid the possible safety accidents caused by structural instability and failure of Shangwu aqueduct,and also provide theoretical basis for the safety assessment of existing similar aqueducts.It not only has important scientific value,but also has a wide range of engineering application prospects.Based on the field measurement data of the aqueduct,this paper establishes the static indefinite element model of the aqueduct,quantifies the underlying indicators of the aqueduct,establishes the AHPS-fuzzy comprehensive analysis evaluation system,studies the carbonization reliability of the aqueduct,establishes the carbonization evaluation model,and integrates the above three methods to reasonably evaluate all aspects of the aqueduct.The main research work and conclusions of this paper are as follows:(1)This paper firstly summarizes the aging and diseases of the structure of Shangwu aqueduct,and conducts field measurement on the disease forms of Shangwu aqueduct.According to the data measured in the field at Shangwu Aqueduct,the concrete of the aqueduct is seriously aging,the steel bars of some components are seriously rusted,and the compressive strength of the concrete has not met the existing regulations.(2)The statically indeterminate structure of single section of aqueduct was analyzed with ABAQUS software to analyze the safety state of each working condition of aqueduct under constant wind load and different water pressure.According to the finite element calculation results,under normal and normal working conditions,the deflection of each member of the groove body is-1.612 mm and-6.795 mm respectively,which meet the requirements of the specification.However,when the groove body is in the ultimate working condition,the deflection of the tie rod part is-15.52 mm,which is greater than the allowable deflection of the tie rod specified in the specification.The stress level of steel wire mesh and steel bar under various working conditions is very low,which is much lower than the allowable value of the current code,indicating that the groove still has a great potential of overload.From the calculation point of view,the trough structure can meet the bearing capacity demand,but the maximum principal stress of concrete is large,the trough concrete may be tensile damage,structural cracks.Under normal working conditions,the concrete maximum principal strain meets the requirements.Under normal working conditions and ultimate working conditions,the concrete maximum principal strain exceeds the specified value.Under the three working conditions,the maximum principal strain of the aqueduct reinforcement meets the requirements.(3)The scientific evaluation of Shangwu aqueduct is carried out by AHP-entropy weight method and fuzzy comprehensive evaluation.Each index is divided according to the hierarchy,weight calculation is carried out,and the weight of experts is considered,and the combined weight based on AHP-entropy weight method is obtained.Finally,combined with the fuzzy comprehensive evaluation method,the optimal vector value of the overall evaluation B of Shangwu Aqueduct is calculated as 0.5900.The results show that the current state of Shangwu aqueduct is grade 1,and the safety state of the aqueduct is poor.It is consistent with the results of static analysis in Chapter 4,so it can be seen that the conclusion of AHP fuzzy comprehensive evaluation method is scientific and reliable(4)The theoretical model of concrete carbonation reliability was established,and the carbonation life of the groove body and the shelf of Shangwu Aqueduct was determined to be 44 years and 70 years respectively according to the data of concrete strength and concrete carbonation of the shelving column of Shangwu Aqueduct.The service life of the groove body was insufficient.The concrete surface of the aqueduct is carbonized seriously,the steel bar has been damaged,and the structure is in a dangerous state.The aqueduct is not suitable for normal irrigation and drainage,so it needs to be strengthened and repaired,and the reinforcement method of the aqueduct body should be optimized.Figure [46] table [35] reference [80]... |
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