Study On Real-time Monitoring Indexes And Quality Control For Concrete Face Rockfill Dam Compaction

For rockfill dams which mainly rely on vibration rolling to improve compactness,compaction quality is an important part of construction quality control.The real-time dam compaction quality monitoring technology provides powerful technical support for rockfill dam compaction quality control.However,it is found that the real-time compaction monitoring indicators are affected by many factors in practical applications,and different compaction monitoring indicators have different precision in characterizing the compaction status of different dam materials.The concrete face rockfill dam includes cushion zone,transition zone,rockfill zone,sub-rockfill zone and other dam zones.The composition and particle size of filling materials in different zones are often quite different.The applicability of monitoring indicators for various materials of concrete face rockfill dam needs further study.At the same time,how to use real-time monitoring indicators to effectively control the compaction quality of rockfill dam basing on current construction code of concrete face rockfill dam is also a key problem to be solved.In this paper,the real-time monitoring index analysis and compaction quality control of concrete face rockfill dam were studied with a practical project,Jiayan Project.The main achievements are as follows:(1)Combined with field rolling test,the influence of rolling direction and vibration mode on compaction monitoring index was analyzed.And it is found that rolling vibration frequency is the main influencing factor.At the same time,the applicability of monitoring index to different dam materials was analyzed,and it is found that the index CCV which including more harmonic components of wheel acceleration is more adaptive for face rockfill dam with various dam materials.Based on the above analysis,a CCV index with coupling vibration frequency was proposed to represent the compaction quality of different dam materials for CFRD,which provides a reasonable and applicable index for real-time control of CFRD compaction quality.(2)This text proceeds with time-domain analysis on roller drum acceleration angle,the change law of time-domain eigenvalues(effective value,peak value and peak factor)of wheel acceleration under different vibration modes are given,and the change mechanism of time-domain eigenvalues with dam material compaction is explained through combining with resonance compaction theory.Based on the analysis of the time-domain monitoring index,the variation of foundation reaction with the compaction of rockfill dam materials under different vibration modes,it is found that the lag phase angle has an important influence on the foundation reaction index.(3)According to the requirements of current construction codes for rockfill dams,a method which considering spatial homogenization is presented to evaluate the compaction quality of the whole storehouse surface of rockfill dams.The requirements for quality control are put forward from three aspects: the qualified rate of compaction,the uniformity of compaction and the control of weak areas.The validity of the method is verified by engineering examples.This method can provide an effective way for compaction quality control of rockfill dam.