基于FLAC3D的仰斜超前微桩复合土钉应用研究

Application of cross-span advanced micro-pile composite soil nailing based on FLAC3D

为了探索仰斜超前微桩复合土钉支护在黄泛区的适用性,运用FLAC3D软件,根据工程实际资料预先进行模拟分析其可行性,而后在某基坑实际施工过程中进行全过程监测并与数值模拟对比分析,得出工程中实测值整体偏大,坑顶水平位移模拟显示最大值为14.5mm,而实测值为16.9 mm;坑外地表沉降模拟最大值为18.6 mm,而实测值为21.5 mm,最大沉降位置均距坑边约10 m;开挖至-9.5 m后土钉轴力最大值出现在第3、4排且均距土钉头约4.5 m处;微桩弯矩实际值比模拟值略大,但仍小于其极限弯矩,微桩承担弯矩抑制了局部失稳现象的发生。仰斜超前微桩复合土钉支护体系能适用于黄泛区的基坑支护。

In order to explore the applicability of the composite soil nailing of oblique advanced support in the Flooded Area of the Yellow River by using FLAC3 D software,the feasibility of simulation analysis is carried out according to the actual engineering data,and then the whole process monitoring is carried out in the actual construction of a foundation pit and compared with the numerical simulation. It is concluded that the measured value of the project is large. Horizontal displacement simulation shows that the maximum value is 14. 5 mm,and the measured value is 16. 9 mm. The maximum settlement of the field table is 18. 6 mm and the measured value is 21. 5 mm,the maximum subsidence position is about 10 m from the pit edge. After excavation to-9.5 m,the maximum axial force of soil nails appears in the 3 rd and 4 th rows and is about 4. 5 m from the soil nailing head. The actual value of the moment of the pile is slightly larger than the simulation value,but it is still less than the limit moment,and the bearing force of the micro-pile restrains the occurrence of the local instability phenomenon. The composite soil nailing supporting system with the tilted forward micro-pile can be applied to flooded foundation pit support.