摘要
通过试验确定了非饱和黏土层的土-水特征曲线和强度参数,通过理论分析建立了非饱和堤岸渗流-应力耦合模型。在此基础上,利用耦合计算程序分析了非饱和土堤岸在河水位变动时的非稳定渗流场特征,结合强度折减有限元法分析了河水位反复升降后非饱和堤岸稳定性的变化。结果表明:水位快速上升时,堤脚渗透流速下降后又逐步上升并趋向稳定,河水位快速上升使堤岸边坡的稳定性降低,随着渗流场中孔隙水压力的调整,堤岸边坡的安全系数又有所回升;河水位骤降时,黏性土层饱和度变化相对滞后,水位骤降加大了堤岸的渗透流速,边坡的稳定性迅速降低,水位下降约120 h后堤岸边坡进入较危险时段;非饱和土的基质吸力提高了堤岸边坡整体稳定性,河水位反复升降降低了堤岸边坡整体稳定性,且河水位越低,水位反复升降对堤岸稳定性产生的影响越大。
Through tests the soil-water characteristic curves and strength parameters of unsaturated soil are determined;and then by way of theoretical analysis a model of seepage-stress coupling model is built.After that,coupling calculation is introduced to analyze the unsteady seepage flow of the unsaturated embankment due to the change of water level and then by using the shear strength reduction FEM to analyze the stability of the unsaturated slope because of the repeated rise and fall of the water level.The results indicate that when the water level rises,the seepage velocity at the bottom of embankment slope decreases,and then increases and grows steady.With the rapid rise of the water level,the global stability of embankment decreases;with adjustment of pore water pressure in seepage field,the safety factor of the slope stability increases to some extent.When the water level falls too quickly,the degree of saturation in clayey soil changes relatively slowly;the sudden fall of the water level accelerates the seepage velocity of embankment,and so the stability of the slope decreases fast.What＇s more,about 120 hours after the fall of the water level the embankment enters a dangerous period.In addition,the matric suction of unsaturated soil increases the global stability of the slope and the repeated rise and fall of the water level decreases the global stability of the slope.What is more,the lower the river water level,the more severely the stability of the embankment will be affected.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2011年第5期1561-1567,共7页
Rock and Soil Mechanics
基金
广东省水利科研及技术推广项目(No.2008-17)
广东水利科技创新项目(No.ysk2009-01)
关键词
堤岸
非饱和土
渗流
稳定性
强度折减有限元法
河水位升降
embankment
unsaturated soil
seepage
stability
strength reduction FEM
rise and fall of water level
