（1西安科技大学建筑与土木工程学院， 西安 710054; 2 陕西建工控股集团有限公司， 西安 710054；3 信息产业部电子综合勘察研究院， 西安 710054）

［摘要］为探究黄土地区复合土钉超深基坑适用性与受力特征，以陕西渭南某复合土钉超深基坑工程为背景，依据现场实测数据，判断复合土钉应用于黄土深基坑的支护效果，探究支护结构受力规律； 基于数值模拟手段，对比纯土钉与复合土钉受力变形差异，并提出相应优化建议。结果表明：复合土钉能有效抑制黄土超深基坑变形，适用性良好； 土钉最大轴力点位置随着基坑开挖向土钉尾部移动，因此可依据土钉轴力监测判断基坑安全性； 与纯土钉支护结构相比，复合土钉支护可降低土钉轴力52.3%，同时由于锚杆（索）限制了基坑水平位移作用，使得土钉最大轴力点位置前移，滑裂面规模减小； 由于基坑顶部土钉轴力较小，且基坑顶部水平位移量较小，土钉+锚索支护体系可优化为仰斜式挡土墙+锚索支护，基坑上部支护能力未完全发挥，有一定优化空间。所得结论可为复合土钉超深基坑支护结构的应用提供理论设计参考。

［关键词］复合土钉； 超深基坑； 支护结构； 锚索； 受力分析

中图分类号：TU444文献标识码：A文章编号：1002-848X(2020)21-0126-07

Mechanical analysis and optimization suggestions of composite soil nail super-deep foundation pit support in loess area

ZHI Bin1, WU Lihele2, WANG Shengbo3, JIAO Hang1, WANG Shuai1

(1  School of Architecture and Civil Engineering, Xi′an University of Science and Technology, Xi′an 710054，China；2 Shaanxi Construction Engineering Holding Group Co., Ltd., Xi′an 710054，China； 3 Ministry of Information Industry Electronics Comprehensive Survey Research Institute, Xi′an 710054，China)

Abstract:In order to explore the applicability and mechanical characteristics of composite soil nail super-deep foundation pits in  loess area, a composite soil-nailed super-deep foundation pit project in Weinan, Shaanxi was used as a background, and based on field measured data, It was judged that the supporting effect of composite soil nail used in loess deep foundation pits, and the force law of supporting structure was explored. Based on the numerical simulation method, the difference between the force and deformation of pure soil nail and composite soil nail was compared, and corresponding optimization suggestions were put forward. The results show that composite soil nail can effectively restrain the deformation of super-deep foundation pits in loess area, and have good applicability; the position of the maximum axial force point of soil nails moves to the tail of the soil nail along with the excavation of the foundation pit, so the safety of the foundation pit can be judged based on the monitoring of the axial force of soil nails; compared with the pure soil nail support structure, the composite soil nail support can reduce the soil nail axial force by 52.3%, and at the same time, because the anchor rod (cable) restricts the horizontal displacement of the foundation pit, the position of the maximum axial force point of the soil nail is moved forward and the scale of the sliding surface is reduced; due to the small axial force of the soil nails on the top of the foundation pit and the small horizontal displacement of the top of the foundation pit, the soil nail + anchor cable support system can be optimized as an inclined retaining wall + anchor cable support, and the supporting capacity of the upper part of the foundation pit has not been fully utilized, and there is certain space for optimization. It can provide theoretical design reference for the application of composite soil nailing super-deep foundation pit supporting structure.

Keywords:composite soil nail; super-deep foundation pit; support structure; anchor cable; mechanical analysis

*陕西省重点研发计划项目（2018SF-397）。

作者简介：郅彬，博士，副教授，Email:xianzhibin@163.com； 通信作者：武李和乐，硕士，Email:sdaaddeff520@qq.com。