Study Of Uplifting Mechanism For Toe Slab Grouting In Zipingpu Hydroelectric Project

Usually, The thickness of toe slab of concrete-face rockfill dam is 0.6～1.2m, and its width is 6~8m. Generally, the consolidation of river bed monolith and curtain grouting are conducted on the toe slab. The application of higher grouting pressure has been confined because of the narrow space and adverse conditions in this area. At the same time, without grouting gallery and conditions for repair and supplemental grouting, this kind of grouting does not have qualifications to use higher pressure grouting and requires higher grouting quality, especially in durability, so this kind of grouting is a special one.Due to poor geologic conditions, weak and complicated formation, a large quantity of injected grout, grout emitting and foundation uplifting are easily occurred during toe slab grouting at Zipingpu project. During the construction process of grouting, many places of slab toe are uplifted. The uplifting in the construction of prophase riverbed slab toe grouting is especially large. The maximum value reaches 15mm, which is much larger than the required 0.2mm in the regulation. Although anchorage and other strengthening measures have been adopted to slab toe, the construction uplifting deformation is still very big. The grouting orifices at each slab toe in each time have to be reduced, which will seriously restrict the construction progress and affect the grouting quality. In order to study the uplifting mechanism of slab toe grouting of Zipingpu dam, according to statistical principle and Monte Carlo method, simulation of jointed rock mass system is conducted, and jointed fractured network system for simulation of grouting process and calculation analysis is established in this thesis. According to the simulated jointed fractured network system, calculation model is established. Calculation analysis of slab toe grouting is conducted by using Finite Element Analysis Calculating Software -ANSYS. According to slab toe grouting experiment and construction achievements of Zipingpu dam, the calculation results are validated. Then some supplements and analysis to slab toe grouting experiment and construction of Zipingpu project are conducted. Through analyzing the calculation results, grouting mechanisms are explained and studied.