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三峡工程竣工后,库水每年将在145 m和175 m水位之间或缓慢或快速的升降,在库水位大幅度涨落的情况下,库岸边坡部分岩体处于“饱和-风干”的循环动态,水-岩循环作用将造成岩体性质劣化。据此,以三峡库区库岸边坡变幅带的砂岩为研究对象,设计了“饱和-风干”循环作用试验。试验结果表明,与常规浸泡试验相比,水压力的升、降变化和“饱和-风干”循环作用对岩体的损伤有累积放大作用,浸泡时水压力变化越大,对离子浓度和次生孔隙的影响越大,而且,“饱和-风干”循环次数越多,岩体的损伤越严重。提出了基于离子浓度变化计算岩石中次生孔隙率变化规律的方法,与实测次生孔隙率变化规律基本一致。因此,可以把这种方法应用到现场监测中去,通过长期监测离子浓度的变化来推测岩体中水化学反应发生的程度,以及次生孔隙率的发育情况。分析成果为研究库岸边坡岩体在“饱和-风干”循环过程中的岩体性质劣化规律奠定了一定的基础。
After completion of the Three Gorges Project, the reservoir water will move slowly or rapidly between 145 m and 175 m of water level every year. With the drastic fluctuations of reservoir water level, part of the rock mass on the bank slope will be in a “saturated-air-dried” Of the cycle of dynamic, water - rock cycle will result in deterioration of rock quality. Based on this, taking the sandstone in the amplitude band of reservoir bank slope of the Three Gorges Reservoir as the research object, the “Saturation - Air Drying” cycle test was designed. The experimental results show that compared with the conventional immersion test, the increase and decrease of water pressure and the cycle of “saturation-air-drying” have a cumulative amplification effect on the damage of rock mass. The greater the change of water pressure during immersion, The greater the influence of secondary porosity, and the more “saturation-drying” cycle, the more serious the damage of rock mass. The method of calculating the variation rule of secondary porosity in rock based on the variation of ion concentration is proposed, which is basically consistent with the measured variation of secondary porosity. Therefore, this method can be applied to on-site monitoring to predict the degree of water chemical reaction in rock mass and the development of secondary porosity by monitoring the change of ion concentration over a long period of time. The results of the study laid a solid foundation for the study of the law of rock mass degradation in the “saturation-air-drying” cycle of bank slope rock.