考虑施工过程的土钉支护土钉轴力计算及影响参数分析

结合土钉支护边开挖边支护的特点,分析土钉支护施工中的开挖效应,阐述讨论土钉力增量的变化对土钉支护施工过程分析的意义。定义开挖影响面为施工过程中土体开挖时边坡内部土体滑动趋势最明显且土钉轴力增加最多的面,定义开挖土压力为以开挖影响面为边界的土块体作用在土钉支护上且由土钉承担的力,建立以开挖影响面及其上土钉力增量为主要研究对象的施工阶段土钉支护分析模型,给出施工过程中土钉轴力的计算方法。与应用其他方法计算得到的Clouterre项目1号墙建造过程中土钉力及量测值进行比较,计算结果与量测结果吻合较好。此外,利用该方法对土性、基坑剖面几何形状和土钉设置等影响因素进行分析。分析表明,所提方法符合施工过程中土钉受力的变化规律,是一种可行的、实用的土钉轴力分析方法。

Analysis of the axial forces of soil nails during construction

The excavation effects of soil nailing are analyzed by considering its construction feature-excavation and support alternatively.The role of incremental nail forces in the analysis of the construction process is addressed.The Excavation Influential Surface(EIS)is defined as the most likely slip surface intersecting the nails at the places where the incremental tensile forces of nails are maxima,provided that the latest stage of excavation surface remains temporarily unsupported and the new row of nails is not yet installed.The earth pressure due to the soil wedge separated by the EIS from the main body is defined as Excavation Earth Pressure(EEP),and assigned to all nails.Incorporating EIS and soil nail incremental forces,a new phenomenological model is formulated for the analysis of soil nailing.The core of the model is to determine the EIS and the nail incremental forces at the intersecting points of EIS and the nails.Based on this model,calculation methods for the nail tensile forces are presented.The measured nail forces of Experiment 1(Clouterre Program)are compared with the calculation results obtained by the proposed method and others.Finally,the influences of soil parameters,the soil nailing profile and nail arrangements on the nail forces are discussed.Analyses indicate good agreement between the model predictions and the observations.