摘要
针对库岸消落带岩石长期处于干湿循环状态导致岩石劣化损伤威胁库岸稳定的工程问题,以白鹤滩水电站库区小坝组红层砂岩为研究对象,对不同干湿循环次数下“自然浸水”和“真空吸水”两种饱水方式的小坝组砂岩岩样进行单轴压缩试验、吸水试验、CT扫描试验、波速试验,研究了干湿循环作用下小坝组砂岩力学特性、空隙特性及损伤特性的变化规律。结果表明:干湿循环次数n相同条件下真空吸水砂岩岩样的强度参数普遍低于自然浸水砂岩岩样,砂岩的单轴抗压强度σ_(c)在干湿循环次数n为10~15次之间出现拐点;小坝组砂岩的总开空隙率n_(0)、大开空隙率n_(b)与n呈线性关系,大开空隙在砂岩强度劣化中起主要作用;随干湿循环的进行小坝组砂岩单轴抗压破裂面的分形维数增大;小坝组砂岩的纵波波速v_(p)、横波波速v_(s)与n的变化规律和σ_(c)与n的变化规律呈现出一致性,真空吸水加速,加深了砂岩强度劣化;定义了小坝组砂岩的纵向和横向损伤变量,干湿循环作用对砂岩的纵向损伤大于横向损伤。该研究结果可为白鹤滩大型水电工程库岸消落带岩体差异风化和岩体稳定性评价提供依据。
Because the rock located in the reservoir water-level-fluctuating zone has been affected by wetting-drying cycles for a long time,it is easy to deteriorate and therefore causes the slope to lose stability.Taking the sandstone of Xiaoba formation red layer in Baihetan hydropower station reservoir region as the research object,this paper carries out the uniaxial compression test,water absorption test,CT scanning test and wave velocity test on the sandstone of“natural immersion”and“vacuum absorption”under different dry-wet cycles to explore the mechanical,porosity and damage characteristics change law of the sandstone under wetting-drying cycles.The results show that the strength parameters of vacuum absorption sandstone samples are generally lower than those of natural immersed sandstone samples under the same cyclic number.The uniaxial compressive strengthσ_(c)of sandstone shows an inflection point between the number n 10 to 15 cycles.There is a linear relationship between total open porosity n_(0)and large open porosity n_(b)of sandstone and n.The large open porosity plays a major role in the strength degradation of sandstone.The fractal dimension of fracture surface in the sandstone increases with the wetting-drying cycles.The trend of longitudinal wave velocity v_(p)and transverse wave velocity v_(s) and n are same with uniaxial compressive strengthσ_(c)and n.Vacuum absorption accelerates the deterioration of sandstone.The longitudinal and transverse damage variables of rock samples are defined,and the longitudinal damage of sandstone is larger than the transverse damage.The research results can provide a basis for the differential weathering of the rock mass and the stability evaluation of the rock mass in the water-level fluctuation zone of the reservoir.
作者
于越
李长冬
洪望兵
孟杰
付国斌
YU Yue;LI Changdong;HONG Wangbing;MENG Jie;FU Guobin(Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan 430074,China;Badong National Observation and Research Station of Geohazards,China University of Geosciences(Wuhan),Wuhan 430074,China;Zhejiang Huadong Construction Engineering Co.,Ltd.,Hangzhou 310014,China)
出处
《安全与环境工程》
CAS
CSCD
北大核心
2022年第4期24-32,54,共10页
Safety and Environmental Engineering
基金
国家自然科学基金优秀青年科学基金项目(41922055)
国家自然科学基金重大项目课题(42090054)
浙江华东建设工程有限公司科研项目(KY2019-HDJS-07)。
关键词
小坝组红层砂岩
干湿循环
单轴抗压强度
空隙率
损伤变量
Xiaoba formation red sandstone
wetting-drying cycle
uniaxial compressive strength
void fraction
damage variable
