Study On Filling Compactness Monitoring Of Rock-Filled Concrete Dam

Rockfill concrete dam is a new type of dam with patent right in China and is widely used in hydraulic engineering construction.Domestic and foreign scholars on the mechanical properties of concrete,temperature characteristic,a lot of work on filling characteristics,the filling density of research with laboratory test and numerical simulation is given priority to,less filling compactness of the actual project evaluation,mainly because of the dam construction site environment is complex,the stone space structure is difficult to predict.In this paper,based on the whole process construction of Guangshan reservoir rockfill concrete gravity dam,a variety of concrete quality testing measures are carried out,and monitoring instruments are used to monitor the filling compactness of unit engineering rockfill concrete pouring process.The influence of particle size distribution and structure of rockfill on flow filling of self-compacting concrete is studied,and the key points of quality control of rockfill are pointed out.At the same time,the core sample detection of the dam section and the casting rate of some silo surface are analyzed.The research results will provide reference for improving the filling quality and pouring rate of rockfill concrete dam,which is beneficial to quality control of rockfill concrete technology in practical engineering.The main conclusions are as follows:(1)This paper proposes a new test method for flow filling compactness monitoring of self-compacting concrete,that is,a wired or wireless sensor is embedded in the gap of rockfill structure and signals of sound,light,current or temperature are emitted to judge whether there is flow of self-compacting concrete.According to laboratory simulation test and actual engineering monitoring test,it is proved that this method can monitor and judge the flow filling compactness of self-compacting concrete.(2)Through the monitoring test of the filling compactness of rockfill concrete dam on the surface of unit engineering warehouse,it is found that the partial filling of self-compactness concrete is not compactness in the structure,which mainly occurs in some special rockfill structures,such as the concentration of loose diameter blocks and the narrow throat of rockfill.It is suggested to strengthen the quality control of the loose diameter block stone concentrated at the height of 1.1m or so on the construction warehouse surface and the narrow stone throat.(3)According to the distribution test of small-diameter block stones,if the small-diameter block stones in the range of about 10 cm-20 cm are concentrated and stacked at a certain height,it is easy to lead to local holes in the stone-filled concrete structure,and self-compacting concrete may not be densely filled.In addition,there is no significant influence on the flow filling compactness of self-compacting concrete due to the proper amount of rosson-diameter blocks distributed on the top surface of the rockfill.(4)After the construction of Guangshan reservoir,a large number of hardened rockfill concrete core samples were obtained by drilling and core-taking tests in the dam section.The quality evaluation of rockfill concrete by core sample appearance quality evaluation method,core sample bulk density calculation method and core sample evaluation method has verified that the filling effect of rockfill concrete dam of Guangshan reservoir is good.Through data measurement and statistics,it is concluded that the average net casting rate of unit project of Guangshan Reservoir is about 47.28%,and measures should be taken to improve the rock-filling rate of unit project with rock-filling concrete volume less than 300 m~3.