巴东组紫红色泥岩干湿循环强度弱化特性的试验研究  

Experimental Study on Strength Weakening of Purple-red Mudstone in Badong Formation Based on Cyclic Wetting and Drying Test

作　　者：苗亮 韩松 申培武 何成[2] 申兴月 MIAO Liang;HAN Song;SHEN Peiwu;HE Cheng;SHEN Xingyue(Hubei Urban Construction Design Institute Co.,Ltd.,Wuhan 430051,China;Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan 430074,China;Wuhan Construction Engineering Group Co.,Ltd.,Wuhan 430056,China)

机构地区：[1]湖北省城建设计院股份有限公司,湖北武汉430051 [2]中国地质大学(武汉)工程学院,湖北武汉430074 [3]武汉建工集团股份有限公司,湖北武汉430056

出　　处：《安全与环境工程》2019年第6期85-93,共9页Safety and Environmental Engineering

基　　金：国家自然科学基金项目(41807263)

摘　　要：三峡库区发育有大量三叠系巴东组第四段紫红色泥岩(T 2 b 4,简称为巴东组紫红色泥岩),受库水位升降的影响其强度易弱化而影响库岸边坡的稳定性,开展三峡库区巴东组紫红色泥岩强度弱化特性的研究可为相关工程地质条件的评价提供参考。首先,依次开展了干湿循环试验和三轴压缩试验,分析巴东组紫红色泥岩的强度弱化特性,并通过CT扫描试验观察试样表面与内部的细观损伤特性;其次,基于CT扫描重构模型,开展了考虑试样内部初始损伤的三轴压缩条件下数值模拟试验;最后,基于岩石的变形特征,提出考虑岩石变开过程压密阶段的能量消耗的一种新的能量耗散模型。试验结果表明:0~10 kPa预应力下的干湿循环试验只对试样表面粗糙度有轻微的影响;干湿循环条件下,试样的峰值强度和残余强度与干湿循环次数呈负线性相关;基于CT扫描重构模型的试样三轴压缩数值模拟试验结果与室内三轴压缩试验结果具有较好的一致性,能体现试样内部的初始损伤特性,更符合实际;改进后的能量耗散模型适合于分析考虑岩石压密阶段的变形过程。There are abundant purple-red mudstones in the fourth member of Badong Formation of the Triassic(T2b4,abbreviated as purple-red mudstone of Badong Formation)in the Three Gorges Reservoir area.The related periodic fluctuation of reservoir water level in the Three Gorges Reservoir area has adverse effects on the stability of reservoir slopes comprised of red-bed mudstone.Thus it’s of great significance to conduct a research on the strength weakening of weak rocks in the Three Gorges Reservoir area for further reference of slope stability evaluation.This paper first conducts the cyclic wetting and drying test,CT scanning test and triaxial compressive test on purple-red mudstone in Badong formation to study the deformation,strength weakening of the mudstone.Besides,the paper observes the mesoscopic damage characteristics of the surface and interior of the samples by CT scanning test.Secondly,based on the CT scanning model,the paper carries out the triaxial compression numerical simulation test considering the initial damage inside the specimen.Moreover,the paper proposes an energy dissipation model considering the dissipation in initial compaction process to analyze the failure process of the mudstone.The results imply that the cyclic wetting and drying weathering has slight effect on the surface roughness of samples,the peaking stress and residual stress of samples display negative linear relations versus cycles.The numerical simulation test results based on CT modeling are consistent with the indoor triaxial compression test,which can reflect the initial damage characteristics inside the sample,which is more realistic;the improved energy dissipation model is suitable for analyzing the rock deformation process in compaction stage.

关 键 词：巴东组紫红色泥岩 强度弱化 能量耗散 干湿循环试验 CT扫描试验 三轴压缩试验 数值模拟试验 

分 类 号：X43[环境科学与工程—灾害防治] TU443[建筑科学—岩土工程]