三峡库区砂质黏性紫色土强度劣化规律试验研究  

Experimental Study on Strength Deterioration of Sandy-Clayey Purple Soil in Three Gorges Reservoir Area

作　　者：肖雪 汪时机[1,2] 杨寻 李贤 黎桉君[1] 夏浩城[1] XIAO Xue;WANG Shiji;YANG Xun;LI Xian;LI Anjun;XIA Haocheng(College of Engineering and Technology,Southwest University,Chongqing 400715,China;Chongqing Engineering Research Center for Whole Life Cycle Health Inspection and Disaster Prevention of Buildings,Chongqing 408100,China)

机构地区：[1]西南大学工程技术学院,重庆400715 [2]重庆市建筑物全生命周期健康检测与灾害防治工程研究中心,重庆408100

出　　处：《西南大学学报（自然科学版）》2023年第10期149-159,共11页Journal of Southwest University(Natural Science Edition)

基　　金：国家自然科学基金项目(11972311);西南大学创新研究2035先导计划项目(SWU-XDPY22003)。

摘　　要：为揭示三峡库区周期性干湿交替作用对紫色土强度的影响机制,研究干湿循环次数、细颗粒(d<0.075 mm)含量以及质量含水率三因素对紫色土三轴抗剪强度特性的影响,通过试验数据回归分析,提出干湿循环作用下砂质黏性紫色土黏聚力劣化程度的定量表达式.试验结果表明:①干湿循环作用对黏聚力的影响远大于摩擦角,其中,第7次循环黏聚力下降24.87%,内摩擦角下降幅度为11.17%.在干湿循环达5次以后,强度参数基本保持不变,土体结构也基本趋于稳定.②随着质量含水率从18%降低至6%,试样黏聚力增加38.81%,内摩擦角增加32.85%,证明质量含水率对试样抗剪强度参数有重要影响.细颗粒含量对强度参数的影响较小,随着细颗粒含量的增加,黏聚力也逐渐增加,对摩擦角影响无明显变化规律,但总体呈下降趋势.③根据二次多元回归拟合及方差分析,三因素对抗剪强度以及参数均有影响作用,根据p值大小进行显著性分析,含水率的强度参数的影响高于另外两因素的影响,且三因素对试样黏聚力的影响高于摩擦角;该研究结果对揭示土体抗剪强度的劣化机制有重要参考意义.To reveal the mechanism of the influence of periodic wet and dry cycles on the strength of purple soil in the Three Gorges reservoir area,the effects of three factors,namely the number of wet and dry cycles,the content of fine particles(d<0.075 mm)and the water content in the soil,on the triaxial shear strength characteristics of purple soil were investigated,and the quantitative expressions for the degradation of the cohesion of sandy clayey purple soil under the action of wet and dry cycles were proposed by regression analysis of experimental data.The experimental results show that:(1)The effects of dry and wet cycles on the cohesion was much greater than that of the friction angle,in which the cohesion decreased by 24.87%in the 7th cycle and the internal friction angle decreased by 11.17%.After the wet and dry cycles reached 5 times,the strength parameters basically remained unchanged and the soil structure was basically stabilized.(2)As the water content decreased from 18%to 6%,the cohesion increased by 38.81%and the internal friction angle increased by 32.85%,which proved that the water content in the soil had an important effect on the shear strength parameters.However,the effect of fine particle content on the strength parameters was small,and the cohesion gradually increased with the increase of fine particle content.There was no obvious regularly change on the effect of friction angle.(3)According to the quadratic multiple regression fitting and ANOVA,the three factors have effects on the shear strength as well as the parameters.The significance analysis according to the size of p-value shows that the response value of the three factors on the strength parameters is quadratic,and the effect of the strength parameters of the water content is higher than the effect of the other two factors,which has certain guiding significance for the actual project.The results of this study are an important reference for revealing the deterioration mechanism of the shear strength of the soil.

关 键 词：强度指标 干湿循环 细颗粒含量 质量含水率 三轴剪切试验 强度劣化 

分 类 号：TU442[建筑科学—岩土工程]