库水波动带岸坡原位声波测试及劣化特性研究

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

为了揭示库水波动带内岩体在库水位周期性升降,干-湿循环条件下,其物理力学性质变化特征,掌握不同岩性的劣化改造过程和差异性。选择消落带内变形破坏强烈的侏罗系库岸斜坡,在宏观调查的基础上,运用单孔、跨孔声波测试方法进行原位试验测试,同时进行原位样品试件采集,运用干湿循环、力学测试、耐崩解等手段进行室内试验测试。原位单孔声波测试KV值为0.2~0.51,跨声波测试KV值为0.46~0.91,表明岩体横向完整性差,纵向完整性相对较好,并且消落带内岩体随着高程的降低,其岩体完整性呈下降趋势;试件力学测试结果表明,20次干-湿循环后其强度平均下降30%~45%,且摩擦系数和黏聚力参数均呈逐渐降低趋势;耐崩解性试验表明,干-湿循环条件下,岩石耐崩解性逐渐降低,5次干-湿循环后,试件耐崩解性指数降低量达3.1%~20.2%。试验结果均证实了消落带内岩体受库水影响强烈,岩体长期在干-湿循条件下,其物理力学性质呈降低趋势,不同岩性劣化程度不同,岩体总体向破碎、解体的趋势发展,并且具有渐进性和累积性。

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 KVvalue 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-wetcycles,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.