水库消落带岩石崩解过程中所处湿干交替作用环境模拟研究

水库运行期水库岸坡防洪限制水位及正常蓄水位之间消落带内的岩石,由于库水位的周期性变化而处在湿干交替作用的环境中.针对目前在研究水库运行期岸坡消落带软岩崩解机理过程中消落带湿干交替作用环境模拟不合理的问题,选取三峡库区三叠系巴东组中风化紫红色泥岩为研究对象,将泥岩置于室内周期性湿干交替作用的环境中,对湿化和干燥过程中泥岩崩解物的宏观质量、物质组成及微细观结构和湿化溶液的化学成分的变化进行测试.测试结果表明:崩解物的质量在湿干交替作用5个周期后不再增加;随着湿干交替作用次数的增加,黏土矿物中含量较大的蒙皂石矿物的含量在减少,第1次湿干交替作用后减少最为明显,4次后趋于稳定;随着湿干交替作用次数的增加,阳离子交换量在5个周期后变化很小.根据测试结果,确定了水库运行期消落带三叠系巴东组中风化紫红色泥岩在湿干交替作用过程中的湿化和干燥的模拟时间,即一个湿干交替作用周期的湿化时间为4天、干燥为2天;泥岩在湿干交替作用5个周期后不再崩解.研究成果为揭示水库岸坡消落带软岩崩解机理提供了消落带湿干交替作用环境的合理模拟方式.

Study on the simulation of cyclic wetting-drying conditions for rocks in the process of disintegration in drawdown area in reservoirs

Due to the cyclic fluctuation of reservoir water level,rocks in drawdown area are in the cyclic wetting-drying conditions during the course of reservoir operation.In the light of unreasonable simulation of the conditions at present,this paper made moderately weathered purple mudstone from Triassic Badong group in Three Gorges Reservoir under cyclic wetting-drying conditions,measured the masses of matters disintegrating form the mudstone and tested the microstructures of the mudstone and the changes of chemical compositions in soak solution after cyclic wettings for the mudstone The results show that the masses increases no longer after fifth wetting-drying cycle;with the increase of number of wetting-drying cycles,smectite is in decline,which is most obvious in the first wetting-drying cycle and then stable after fourth wetting-drying cycle;the cation ex-change capacity almost does not change after the fifth wetting-drying cycles.According to the test results,the simulation time for wetting and drying is determined for the mudstone in drawdown area,namely the wetting time is 4 days and the drying time is 2 days;the mudstone hardly disintegrates after the fifth wetting-drying cycle.Research results can provide reasonable simulation method for cyclic wetting-drying conditions in draw-down area in order to reveal the disintegration mechanism of rocks in drawdown area.