摘要
针对桥梁重力锚布设对碎石土堆积体稳定性的影响问题,以西香高速泸沽湖特大型桥梁为例,围绕该处碎石土的力学特征与变形参数,采用室内大型三轴试验与PFC(particle flow code)-FLAC(fast Lagrangian analysis of continua)耦合的数值仿真技术,建立柔性边界条件下的三轴试验模型,分析该碎石土的变形破坏特征以及力学机制变化规律。结果表明:在三轴试验中围压与初始弹性模量E i呈正相关性,随着碎石土试样中粗颗粒料含量增加,内聚力会减少而内摩擦角增加;拟合得到该处碎石土试样破坏强度σ_(cre)与围压σ_(3)的线性关系式:σ_(cre)=2.95σ_(3)+176.105;三轴试样在低围压下,上下锥形区域持续压密吸收能量,碎石土试样内部出现两条剪切带,整体呈“X”形,随着围压的增加,能量出现冗余并向剪切带外扩散,产生新的裂隙,掩盖了剪切带的区域化特征,导致剪切带逐渐减少并在围压达到400 kPa时消失。研究成果对碎石土堆积体稳定性问题具有一定的参考价值和指导意义。
The impact of gravity anchor deployment on the stability of gravel soil accumulation in bridges can be seen in the case of the Lugu Lake Super Large Bridge of Xixiang-Shangrila Expressway.The impact of gravity anchor reinforcement on the stability of the gravel soil accumulation body was examined.The deformation and failure characteristics of the gravel soil and the changes in its mechanical mechanisms were analyzed by establishing a triaxial test model under flexible boundary conditions through large-scale indoor triaxial tests and numerical simaulations using the particle flow code(PFC)-fast Lagrangian analysis of continua(FLAC)coupling technique.The results show that the initial elastic modulus E i was positively correlated with the confining pressure in the triaxial tests.The cohesion decreased while the internal friction angle increases as the content of coarse particles in the gravel soil sample increased.Through fitting,a linear relationship between the failure strengthσ_(cre) of the gravel soil sample in that area and the confining pressureσ_(3) was obtained:σ_(cre)=2.95σ_(3)+176.105.Under low confining pressure,the upper and lower conical regions of the triaxial sample continuously absorb energy,and two shear bands appear inside the gravel soil sample,forming an overall"X"shape.However,with the increase in confining pressure,the energy becomes redundant and spreads outside the shear bands,creating new cracks that mask the localized characteristics of the shear bands.As a result,the shear bands gradually decrease and disappear when the confining pressure reaches 400 kPa.The research results have certain reference value and guiding significance for the stability issues of gravel soil deposits.
作者
郑达
周赛
周鸿轲
ZHENG Da;ZHOU Sai;ZHOU Hong-ke(College of Environment and Civil Engineering,Chengdu University of Technology,Chengdu 610059,China)
出处
《科学技术与工程》
北大核心
2024年第12期5104-5113,共10页
Science Technology and Engineering
基金
国家自然科学基金(42293353)
西藏自治区自然资源厅(藏财采【2020】0890-1)。
关键词
碎石土
大型三轴试验
PFC-FLAC耦合
柔性边界
变形特征
力学机制
gravel soil
large-scale triaxial test
particle flow code(PFC)-fast Lagrangian analysis of continua(FLAC)coupling
flexible boundary
deformation characteristics
mechanical mechanism
