Application of Micro Earth Pressure Cells to Geomechanical Model Tests of Arch Dams

Abstract

Geomechanical model tests are important in the evaluation of the stability of engineering rock masses, and they play a key role in the stability studies on arch dam abutments. To further analyze the instability failure process and mechanical characteristics of dam abutment rock masses, this study employed a stress monitoring system in the traditional strain and displacement monitoring to improve the comprehensiveness of test results. With their advantageous properties, including their small volume, high sensitivity, and strong stability, micro earth pressure cells can directly monitor stress changes in arch abutment rock mass during geochemical model tests. On the basis of the overloading method, this study applied micro earth pressure cells to a 2D geomechanical model test on the Yebatan arch dam to investigate the working performance of the arch dam and arch abutment at EL.2 750 m. In the test, the surface displacement monitoring system and micro earth pressure cells on both sides of the deep unloading belts of the left and right dam abutments were arranged to study the pressure changes at the arch abutment and the influence of the geological structure. The results showed that the measured stress value near the arch abutment was large and that the measured stress value greatly decreased after passing through the deep unloading belt. Class IVs of strongly relaxed rock masses in the left abutment exerted an obvious attenuation effect on the arch thrust while fault f29 (f74) greatly influenced the right abutment. The results were verified by the displacement test data. The application of micro earth pressure cells facilitated the direct observation and analysis of dam abutment stress and improved the completeness of the test results. Thus, the proposed approach provides a new idea for geomechanical model tests.