兰州某基坑变形监测与数值模拟

Monitoring and Numerical Simulation of a Foundation Pit Deformation in Lanzhou

结合兰州某什字立交改造工程基坑的特点，对基坑围护桩顶水平位移、周围地表沉降、周边建（构）筑物沉降等监测结果进行了分析，采用FI。AC3D软件模拟基坑开挖过程，对排桩加钢支撑支护下的基坑变形规律及变形影响因素进行了研究．结果表明：1）基坑固护桩顶位移、基坑周边地表沉降等随着基坑开挖深度增加而同步变化．围护桩顶水平位移最大为15．8mm，桩顶竖向位移最大为11．5mm．2）敞开段地表沉降呈三角形分布．离基坑越近沉降越大，最大为11．4mm；暗埋段地表沉降呈抛物线形分布．离坑边5～8ITI处沉降较大，最大为15．7mm，坑边和较远处沉降较小．3）将数值模拟结果与监测结果进行对比，两者变化趋势基本一致且较接近，说明数值分析结果可靠、支护结构支护效果理想．

In combination with the characteristics of the foundation pit of a reconstruction project in Lanzhou,the monitoring result of displacement of pile top, the settlement around the founda- tion pit and the settlement of surrounding building are analyzed. The deformation rules and the influencing factors of the pile-steel support foundation pit are analyzed by using FLAC3D soft- ware to simulate the excavation process of foundation pit. The results show as follows： 1） the horizontal displacement of foundation pit and the foundation settlement increase with the increase of the excavation depth of the foundation pit,and the maximum value of the horizontal displace- ment of pile top is 15.8mm and the maximum value of settlement of pile top is 11.5ram; 2） the ground surface settlement of the opening section is triangular distribution： the closer the section is,the greater the ground surface settlement is,and the maximum value is 11.4mm; the ground surface settlement of the buried section is parabolic distribution： the ground surface settlement is maximum around the pit at about 5~8m and the value is 15.7ram while the ground surface settle- ment is small at both the edge of the pit and far away from the pit; 3）the simulating result and the actual monitoring result are similar ,and their variation rules are almost the same, so the simu- lating result is reliable and the supporting effect of the pile-steel support structure is ideal.