土钉支护加固机理的数值分析

采用摩擦-接触型界面单元模拟钉土界面真实的变形协调情况,建立了基坑开挖土钉支护的数值分析模型,并通过和工程实测对比验证了模型的可靠性.借助动态仿真分析支护系统内力、钉土界面剪应力以及土体应力状态和应力路径随开挖、支护的不断推进而发展变化的全过程,定量揭示了支护系统的加固机理:单根土钉发挥应力分担、扩散以及传递的锚固作用,分别改善土钉头部、中部和尾部土体的应力状态,并提高土体抗剪强度;群钉系统发挥整体加固作用,增加土体刚度;土体强度、刚度增加且应力减小,双重抑制了边坡位移和塑性区的发展.

Numerical Analysis of the Reinforcement Mechanism of Soil-Nailing Support

By using a friction-contacting interface element which can simulate the interface's actual distortions such as closure,opening and slippage,a finite element model for the soil-nailing system was built,and its reliability and precision were validated by comparison with field measurements.With the development of the supporting system's inner force,interface's shear stress and the stress state of a point in the soil,the reinforcement mechanism of the supporting system was quantitatively revealed as follows: single nail played an anchoring role such as stress sharing,stress dispersion and stress passage,and group nails played a reinforcing role,which improved the soil's stress state,and simultaneously increased its shear strength and rigidity,then greatly decreased the displacement and plastic region.