摘要
在基础建设过程中,以粉细砂为填筑材料的地基在上覆荷载作用下可能发生软化现象。为探究饱和粉细砂应变软化规律,基于自动环境三轴试验系统开展合肥粉细砂固结不排水三轴剪切试验,分析不同围压下粉细砂应变软化特征,揭示其软化机理。研究结果表明:合肥粉细砂不排水剪切应力-应变曲线呈明显驼峰型软化特征;围压对于其应力-应变曲线影响显著,其峰值偏差应力及对应的峰值应变与固结围压呈正相关,偏差应力峰值与固结围压关系可用线性函数(σ1-σ3)p=0.637σ3+255.5拟合表述,拟合决定系数R2达到0.983,应变峰值与固结围压关系可用线性函数εp=0.0031σ3+5.45拟合表述,拟合决定系数R2达到0.982;剪切过程粉细砂试样产生剪胀现象,使得土体结构逐渐破坏,进而发生应变软化现象。通过在沈珠江院士提出的驼峰形双曲线型公式上添加新的边界条件以简化模型参数,构建了合肥粉细砂应变软化修正双曲线数学模型。该模型对合肥粉细砂应力-应变软化曲线的拟合效果良好,为安徽地区地下工程设计与施工提供重要依据。
During the process of foundation construction,the foundation made of fine sand may experience liquefaction under the action of overlying loads.In order to explore the strain softening characteristics of saturated fine sand,unconsolidated undrained triaxial shear tests on Hefei fine sand are conducted using an automatic environmental triaxial testing system.The strain softening characteristics of fine sand under different confining pressures are analysed and its softening mechanism is revealed.The research results indicate that the unconsolidated undrained shear stress-strain curve of Hefei fine sand exhibits a significant peak-type softening characteristic.Confining pressure has a significant influence on its stress-strain curve,with the peak deviator stress and corresponding peak strain positively correlated with the consolidation confining pressure.The relationship between peak deviator stress and consolidation confining pressure can be expressed by a linear function(σ1−σ3)p=0.637σ3+255.5,with a fitting determination coefficient R2 reaching 0.983.The relationship between peak strain and consolidation confining pressure can be expressed by a linear functionεp=0.0031σ3+5.45,with a fitting determination coefficient R2 reaching 0.982.During the shear process,the fine sand specimen exhibits shear dilation,leading to gradual destruction of the soil structure and subsequent strain softening.By adding new boundary conditions to the hyperbolic formula proposed by Academician Shen Zhujiang to simplify the model parameters,a modified hyperbolic mathematical model for strain softening of Hefei fine sand is constructed.This model fits well with the stress-strain softening curve of Hefei fine sand and provides important basis for the design and construction of underground engineering in Anhui Province.
作者
许宇浩
彭世龙
曹广勇
张挺
XU Yuhao;PENG Shilong;CAO Guangyong;ZHANG Ting(School of Civil Engineering,Anhui Jianzhu University,Hefei 230601,China;Anhui Key Laboratory of Building Structure and Underground Engineering,Hefei 230601,China)
出处
《四川轻化工大学学报（自然科学版）》
CAS
2024年第3期94-100,共7页
Journal of Sichuan University of Science & Engineering(Natural Science Edition)
基金
国家自然科学基金项目(52004003)
安徽建筑大学科研项目(2020QDZ16)。
