Engineering geological study on underground surge chamber construction in toppling slopes
The surge chamber of Zhala Hydropower Station is constructed in a toppling slope,so a systematic study on the sta-bility of this slope and surrounding rock mass is crucial.Based on differences in rock mass structure and types of deformation and failure,the in-situ area was divided comprehensively using qualitative factors,such as rock mass structure,bedding angles,and weathering,combined with the quantitative factor of wave velocity ratios.Through unconventional in-situ tests and inversion cal-culations,suitable shear strength parameters of the rock mass for each zone were proposed.Numerical analysis was used to simu-late the deformation and failure modes of the toppling slope,and multiple analytical methods were employed to verify its stability.Results indicated that the toppling rock mass of the slope can be divided into three zones:bedded flexural zone,fractured tensile zone,and loose collapsing zone.The primary failure modes of the plant-rear toppling slope are tensile cracking-sliding-shear-ing failure and block unloading collapse.In evaluating the stability of the topping slope,the safety factor should be taken to the higher limits of the range specified by current technical standards,which is favorable to ensuring the stability of the toppling slope and the deformation control of rock mass of the cavities.The findings have effectively addressed prominent contradictions between geological conditions and hydraulic structure requirements,and it is pioneering in China's hydropower construction and providing reference for engineering construction in toppling slopes.
toppling slopeunderground surge chambergeological characteristicssurrounding rock mass stabilityin-situ testsnumerical analysis of stress-strainZhala Hydropower Station