SONIC WAVE TEST AND DEGRADATION CHARACTERISTICS OF RESERVOIR BANK SLOPE WITHIN WATER FLUCTUATION BELT

This paper attempts to reveal the variation of physical and mechanical properties of the rock mass in the reservoir water level under the condition of periodic fluctuation of the water level in the reservoir. It tries to master the process and the difference of the deterioration of the rock mass. It chooses the Jurassic slope with deformation and destruction seriously in water level-fluctuating zone. On the basis of macroscopic investigation, single hole and cross hole sonic wave testing method is used for in-situ test. Meanwhile, the samples are collected and tested by dry-wet circulation, mechanical and disintegration tests. In-situ single-hole acoustic wave test K_V value is 0.2~0.51 and its cross-hole value is 0.46~0.91. It shows that the integrity of rock mass is poor in transverse and better in the longitudinal. The integrity of the rock mass decreases with the decrease of elevation. Mechanical test results show that the specimen strength decreases 30%~45% on average after 20 times dry-wet circulation. The coefficient of friction and cohesion parameters is gradually decreased. The disintegration resistance test shows that under the condition of dry wet cycle, the disintegration resistance of the rock decreases gradually, after 5 cycles of dry-wet cycles, the index of disintegration resistance decreases by 3.1%~20.2%.The experimental results show that the rock mass is affected by reservoir water strongly in water level-fluctuating zone. The physical and mechanical properties of rock mass are decreased under the condition of dry-wet cycle for a long time. Different lithology deterioration degree is different. The trend of rock mass develops to break and disintegration, which has progressive and cumulative features.