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在基坑土钉支护设计中,一般用坑壁侧压力来估算土钉的间距、内力和长度,因此侧压力大小及分布的合理确定对设计有显著影响。通过应用三维非线性有限元方法,并采用能够在一定程度上反映基坑开挖过程中土体变形特点的本构模型,对土钉支护结构进行受力分析。计算分析表明:土钉支护中相应坑壁侧压力分布与经典土压力分布差别较大,其合力值在主动土压力与静止土压力之间;现行规程中建议的侧压力分布与有限元计算结果存在差异;对坑壁非竖直的情况,不同土质条件下用不同方法推导得出的侧压力折减系数与有限元结果的吻合程度有一定的差别。
In the design of soil nailing for foundation pit, the pit wall pressure is generally used to estimate the pitch, internal force and length of soil nail. Therefore, the reasonable determination of the lateral pressure and its distribution have a significant impact on the design. By applying the three-dimensional nonlinear finite element method and using the constitutive model that can reflect the deformation characteristics of soil during excavation to a certain extent, the force analysis of soil nailing structure is carried out. The calculation and analysis show that the distribution of pressure at the corresponding pit wall in soil nailing differs greatly from the distribution of the classic earth pressure, and its resultant force is between the active earth pressure and the rest earth pressure. The proposed lateral pressure distribution and the finite element calculation The results are different. For non-vertical pit wall and different soil conditions, the deduction of lateral pressure by different methods has some differences with the finite element results.