A Toe Slab Foundation Treatment Of The Unloading Fissure Concrete-faced Rockfill Dam

LIZIPING Concrete face rockfill dam is high of77.5m, which is a medium heightdam. The angle of this dam foundation rock mass is gentle and unloading crack veryprosperous. The toe board is the kneading board in coupling structure between faceplateand groundsill, and simultaneously also is the connection body for guarding againstinfiltrates into curtain, it is most essential spot which the kneading board dam links thepreceding with the following.The excavation and seepage control of dam foundation is an important part, whichimpact the dam stable, settlement, deformation and safe operation. In view of thegeologic environment of LIZIPING and the dam security, it is necessity to study the toeBoard foundation treatment of concrete face rockfill dam in LIZIPING. After thefoundation rock for the toe board of the consolidation grouting effect and to theimprovement of the foundation rock for the toe board quality is worthy of research andanalysis meanwhile Hydro-geologic conditions in the system are summarized in thispaper, based on geological features and the toe slab of the area, according to thegeological survey and test data, established the geological model for the toe board of theconcrete-faced rockfill dam deformation and stress of the surface, etc.The main conclusions of this paper are as follows:①Based on the characteristics of geological rock (body) of foundation rock areclassified: direct used rock mass, the excavation and utilization of rock mass and theexcavation to remove rock mass. According to the concrete-faced rockfill damspecification and its ability to resist erosion, toe board foundation excavation depthshould be to weak unloading rock mass(Vp≥3000m/s).Limited by conditions, unable todig to weak lower part of unloading rock mass, the suggested structure measures aretaken such as setting and consolidation grouting anchor for processing, in order toimprove the quality of foundation rock for the toe board.②According to the geological survey data to establish finite element model andthe toe slab of the dam, under different conditions on the stress, deformation anddisplacement analysis, get the scope of its plastic deformation, stress distribution, thedirection of the maximum displacement, the results of the analysis to the toe slab of theconcrete dam choice below.③In view of the foundation rock for the toe board of the inclination of smooth,various types of geological defects, post-processing difficult to wait for a characteristic, the research adopted the "uniform consolidation curtain cloth groove type", effectivelyimprove the toe board foundation shallow grouting pressure, to meet the requirementsof the safe operation of the dam.4Research suggests that the toe board of the concrete face rockfill damfoundation grouting, consolidation grouting effect is not only improving the integrity ofthe foundation rock and uniformity, but more important is to enhance the toe boardthickness and density of the shallow foundation anti-seepage curtain body, reduce waterseepage gradient force.Meanwhile, this paper has expound the geological conditions, the basis ofLIZIPINH concrete face rockfill dam engineering rock mass characteristics, engineeringgeological conditions of the system, rich in content, conform to the actual content,involved the accumulation of experience and methods to deal with problems, could beused as a reference for the other similar projects.