为了研究垂直荷载下浅基础模型试验变形场及破坏模式,以数字图像相关技术(DIC)为基础,编制相应的位移场分析程序,并通过实例对该程序的可靠性和精度进行验证。浅基础模型试验结果表明:利用编制的DIC程序获得了浅基础下土体的全场位移;浅基础在加载过程中先后出现两道滑动面,第一道滑动面与按极限平衡理论所推得的滑移面相似,在极限荷载条件下,最终出现第二道滑动面,滑动面在地表处趋于收敛;基底下的土在整个加载过程中不发生破坏,处于弹性平衡状态。随着离开基础中心线距离的增加,最大水平位移先增加后减小,在基础边缘处,最大水平位移达到最大值;在极限荷载下,基础沉降影响深度约为(1.5~2.0)B。
In order to study the displacement field and failure pattern of soil beneath laboratory shallow foundation subjected to vertical loading,based on the digital image correlation technique,an analysis procedure was worked out.Reliability and precision of the procedure were validated by an example,and the results show that it is feasible to analyze the displacement field of soil beneath shallow foundation.There are two slide surfaces existing in the soil during the loading process.The first continuous slide surface likes the slip-surface deduced by limit balance theory.The second slide surface is generated beneath the shallow foundation at the ultimate load phase,and the shallow foundation presents the general shear failure.The soil just beneath shallow foundation does not fail and keeps elastic equilibrium state.The two slide surfaces have the trend of convergence near the earth's surface.As the increasing of horizontal distance from footing centerline,the maximum horizontal displacement first increases,then reduces.The maximum horizontal displacement approaches the footing edge.The depth of influence zone is approximate 1.5B to 2.0B at the final failure stage.