深基坑开挖对邻近古建筑影响实测分析

Analysis on Monitoring Data of the Influence of Deep Foundation Pit Excavation on Adjacent Ancient Building

基坑开挖对坑外地表及周边浅基础古建筑等有重要影响。结合佛山地铁三号线大良站基坑开挖工程,对基坑地连墙结构、坑外地表及古建筑(慈善会)的变形进行了监测分析。结果表明:随基坑开挖深度增大,地连墙的水平位移最大值位置逐渐向下移动,最大水平位移约为14 mm;地连墙顶部位移逐渐由坑内指向坑外,变形呈“下凸上凹”型;周边地表沉降规律表现为凹槽型,沉降槽点在0.2~0.3H(H为基坑深度)之间;古建筑累计沉降随基坑开挖深度的增大而增大,且其邻近基坑侧更大,最大值约为15 mm,不均匀沉降值约为7 mm;在同一工序下,古建筑沉降趋势与地表沉降趋势相同,前者沉降变形更大,且相对滞后。基于分析结果:基坑开挖过程中加强横撑、适时回灌、及时施作封底等措施对减少邻近古建筑变形具有重要工程意义。

Foundation pit excavation has an important influence on the surface outside the pit and the surrounding shallow foundation ancient buildings.Combined with the excavation project of Daliang station foundation pit of Foshan Metro Line 3,the deformation of diaphragm wall structure,ground surface outside the pit and the ancient building(Charity)were monitored and analyzed.The results show that:With the gradual increase of the excavation depth of the foundation pit,the maximum horizontal displacement of the diaphragm wall near the ancient building is about 14mm.The maximum position of the displacement of the diaphragm wall into the foundation pit gradually moves downward with the increase of the excavation depth,and the displacement of the top of the diaphragm wall gradually points from the inside of the pit to the outside of the pit,and the deformation is"convex down and concave up".The surrounding surface settlement law is of groove type,and the settlement groove point is between 0.2~0.3H.The cumulative settlement of adjacent ancient buildings increases with the increase of excavation depth of foundation pit,and the settlement of adjacent foundation pit side is larger.The maximum settlement of ancient buildings is about 15 mm,and the uneven settlement value is nearly 7 mm.Under the same process,the settlement trend of ancient buildings is the same as that of surface settlement,with the former having greater settlement deformation and relatively lagging.Based on the analysis results:It is of great engineering significance to reduce the deformation of adjacent ancient buildings by strengthening transverse bracing,timely recharge of groundwater and timely construction of bottom sealing concrete in the process of foundation pit excavation.