| As the impervious component,the asphalt concrete core wall plays an important role in maintaining the stability of the rockfill dam structure.In recent years,more and more asphalt concrete core rockfill dam are being built in alpine region with complicated geological condition and high potential of earthquake.The safety and sustainability of such super high dams relies on high-standard construction quality.To yield a desirable output of asphalt concrete core wall construction,it is very critical to take effective measures to control paving and compaction processes.Therefore,further study of quality control technology for asphalt concrete paving and compaction is of great necessity,which will exert an important theoretical and practical significance on the dam construction quality assurance,and provide guarantee for lean construction and long-term safety operation.Based on quality control requirements of paving and compaction in core wall asphalt concrete construction,a real-time thickness monitoring system was developed to enable the automatic,accurate,and visualized control of the paving process.The applicability of traditional compaction quality real time monitoring index in asphalt concrete core wall was analyzed,based on which an improved monitoring index was proposed to represent compaction quality of asphalt concrete core wall construction.In addition,a fuzzy comprehensive compaction quality evaluation method was proposed by considering both the compaction parameters during compaction and compaction quality index after compaction.This method would provide a new approach to timely quality assurance and assessment of asphalt concrete core rockfill dam.Major research achievements of this thesis are as follows:(1)A lift thickness calculation method of asphalt concrete core wall based on paver attitude was proposed.A three-dimension spatial model for real-time calculation of the lift thickness was set up.The specific calculation algorithm was developed by using the quaternion to describe the orientation of the paver rigid body.A calibration method based on adaptive t distribution mutation-firework algorithm(ATM-FWA)was proposed to achieve precise calibration of model parameters.The proposed method provides a new way to calculate lift thickness of asphalt concrete core wall in the condition of continuous monitoring,and builds the theoretical foundation for subsequent development of asphalt concrete real-time lift thickness capture device.(2)An asphalt concrete core wall lift thickness real-time monitoring system was developed.A lift thickness real time capture device was developed based on the abovementioned calculation method.An overall framework and a data flow of lift thickness real time monitoring were designed based on the quality control requirements.This paper also presented a method for monitoring information integration based on the method of three-dimensional web-based visualization and the ActiveX technology.The application process of the system was proposed and the corresponding function was developed.The case study validates the efficacy of the developed system,which can not only realize the real-time,continuous,and remote monitoring of the paving process,but also intuitively indicate the position coordinates of the regions to guide quality remedies.In addition,it is helpful to building up an integrative quality management mode of "constructors-supervisors-owners" by combining the jobsite constructors and the remote superintendents.This integrative mode will improve the efficiency of asphalt concrete core wall paving quality management.(3)Applicability of traditional compaction quality index in core asphalt concrete construction was analyzed,based on which an improved monitoring index was proposed to represent compaction quality of asphalt concrete core wall.Since core asphalt concrete is different from road asphalt concrete in the aspects of aggregate graduation and asphalt aggregate ratio,several real-time monitoring indexes based on steel wheel vibration performance were introduced,and correlation between different compaction monitoring indexes and the state of compaction was analyzed through compaction simulation experiment.The monitoring index CV,which is applicable to asphalt concrete core wall,was introduced.A vibration frequency-coupling model with CV was put forward to evaluate asphalt concrete core compaction quality after analyzing the influence of frequency on CV by experiment data.The experiment results indicated that correlation between the frequency-coupled CV and compactness was superior to using CV alone.CV with vibration frequency could reduce the error of compaction quality evaluation induced by unstable vibration frequency,which would lead to a more precise and robust representation of the real-time asphalt concrete core wall compaction quality.(4)Considering the disadvantages brought by only conducting the process parameters evaluation or after-compaction analysis,a fuzzy comprehensive evaluation method of earth-rock dam compaction quality was proposed.Based on compaction parameters eligibility fuzzy evaluation,with the real time monitored compaction index at any position of the work zone,the compaction quality rockfill materials was evaluated by fuzzy assessment.Finally,a fuzzy comprehensive method for compaction quality evaluation was proposed based on Dempster-Shafer evidence theory,which takes both the compaction parameters and the compaction monitoring value into account.In addition,the spatial distribution of weak area for compaction quality was evaluated quantitatively and a control criterion was set up by the means of densitybased spatial clustering of applications with noise(DBSCAN)to ensure that no obvious continuous weak area exists in the work zone.The presented method can realize quality comprehensive evaluation of the entire construction process,and avoid biases brought by only conducting the process parameters evaluation or after-compaction analysis,and improves the accuracy of compaction quality assessment for earth-rock material. |
