运用有限元分析软件 PLAXIS,对采取桩锚与土钉墙联合支护的银川市天玺国际中心项目深基坑变形进行了数值模拟计算。计算模型采用15结点三角形单元模拟土体,土体按照实际情况分为7层,用注浆体模拟混凝土面层,用板单元模拟排桩,用点对点锚杆和土工格栅的组合来模拟土钉。计算结果表明:排桩与土钉墙联合支护结构中,在2种支护形式交接处变形量较大,说明基坑支护材料的刚度对基坑变形影响显著;随着基坑的开挖,边坡的变形量逐渐增大,且坡顶最终变形量大于坡底。将模拟结果与现场监测数据进行了对比分析,得出了类似深基坑变形的一般性规律及以控制变形为目的的改进支护加固方案。

The deformation of deep excavation pit supported by row piles and soil nailing at Tianxi International Center of Yinchuan was simulated by using PLAXIS software. The calculation model was established by using a 15-node triangular element to simulate the soil that was divided into seven layers, and the concrete surface layer was simulated with grouting element, the row of piles was simulated with plate element and the soil nail was simulated by using the combination of point anchor and geo-grid. Calculation results showed that large deformation was found at the junction of two supporting forms, which indicated that the rigidity of the support structure had remarkable influence on the deformation of the excavation pit. The deformation of pit slope increased gradually with the increasing of excavation depth, and the final deformation at top of slope was greater than that of the bottom.Through comparison between simulation result and monitored result, some common laws of foundation pit deformation were concluded.