水库运行期消落带红层砂岩强度劣化的物理化学机制研究

The strength of Red-Bed sandstone in drawdown area of reservoir bank slope will degrade easily under cyclic wetting-drying conditions during the course of reservoir operations. When the strength decreases to a certain degree, the bank slope will deform or even fail. Jurassic Red-bed sandstone in Three Gorges Reservoir Area is selected as research object. It will be established that the laboratory method to simulate the stress condition and cyclic wetting-drying physicochemical environment in drawdown area during the course of reservoir operations. Experiments and tests will be carried out to study the changes of microstructures, material compositions and mechanical strengths of the sandstone specimens under the stress condition on bank slope and cyclic wetting-drying physicochemical environment. By physical, chemical and mechanical analysis on the results of the experiments and tests, it will be obtained that the relationships between the content of grains, content of cements, distribution parameters and geometric parameters of pores and cracks, porosity in the sandstone specimens and physicochemical environmental variables of drawdown area during the course of reservoir operations. The Mineral petrology, quantum chemistry, rock mechanics, structural chemistry and the software for crystal bond calculation will be adopted to analyze the micro nature of the evolution of pores and cracks, loss of grains and cements, damages of cement bonds among grains in the sandstone specimens during the course of degrading process of strengths of the sandstone specimens. The physicochemical mechanism of strength degradation of Jurassic Red-bed sandstone in drawdown area during normal reservoir operations will be revealed, which will give theoretical basis for controlling the degrading process of the strengths of the sandstone during the course of reservoir operations by chemical grout.

水库运行期消落带红层砂岩在周期性“湿干”交替作用下其宏观力学强度易发生劣化，当劣化发展到一定程度后，容易引起岸坡变形，甚至导致岸坡失稳。项目以三峡库区典型红层砂岩为研究对象，建立科学的室内试验方法，实现对水库运行期消落带所处岸坡应力和周期性“湿干”交替共同作用的物理化学环境条件的合理模拟；开展砂岩在岸坡应力和周期性“湿干”交替共同作用的物理化学条件下物质组成及含量、微细观结构、孔隙度和宏观力学强度测试试验研究，建立砂岩碎屑矿物与胶结物含量、孔隙裂隙分布与几何特征参数、孔隙度和强度与水库运行期消落带物理化学环境变量之间的数理关系；运用矿物岩石学、量子化学等理论和晶体成键计算软件，分析砂岩强度劣化过程中孔隙与裂隙演化、碎屑矿物与胶结物流失、碎屑矿物间胶结键破坏的微细观本质，揭示水库运行期消落带红层砂岩强度劣化的物理化学机制，为研制干预水库运行期消落带红层砂岩强度劣化进程的灌浆材料提供理论依据。

水库运行期消落带红层砂岩在周期性“湿干”交替作用下其宏观力学强度易发生劣化，当劣化发展到一定程度后，容易引起岸坡变形，甚至导致岸坡失稳。项目以三峡库区典型红层砂岩（马家沟岸坡侏罗系红砂岩）为研究对象，建立科学的室内试验方法，实现了对水库运行期消落带所处岸坡应力和周期性“湿干”交替共同作用的物理化学环境条件的合理模拟；开展了三峡库区马家沟岸坡砂岩在岸坡应力和周期性“湿干”交替共同作用的物理化学条件下物质组成及含量、微细观结构、孔隙度和宏观力学强度测试试验研究，建立了砂岩碎屑矿物与胶结物含量、孔隙裂隙分布、孔隙度和强度与水库运行期消落带物理化学环境变量之间的数理关系；运用矿物岩石学、岩石力学、水化学等相关理论，分析了砂岩强度劣化过程中孔隙与裂隙演化、碎屑矿物与胶结物流失、碎屑矿物间胶结键破坏的微细观本质，揭示了水库运行期消落带红层砂岩强度劣化的物理化学机制，为研制干预水库运行期消落带红层砂岩强度劣化进程的灌浆材料提供理论依据；基于此，初步研制出了一种能干预岸坡消落带红砂岩在水库运行期劣化进程的化学加固材料，有望应用于水库岸坡消落带红砂岩的化学加固。