基于HSS模型的管廊基坑支护结构受力探究

Stress analysis of the foundation pit supporting structure of the autility tunnel based on HSS model

以某综合管廊基坑为例,基于HSS模型,运用有限元软件,对基坑支护结构受力进行数值模拟,探究综合管廊基坑内力、变形发展规律。研究结果表明:受支撑刚度影响,随开挖深度增加,围护桩整体变形由悬臂式转变为内凸式,桩体最大水平位移位于坑底附近。与HSS模型相比,MC模型计算得到的桩体底部水平位移值偏大,约是前者的1.60倍。地表沉降曲线呈抛物线形分布,最大沉降发生在距基坑10 m左右。MC模型计算出的沉降在坑边产生较大土体隆起。钢板桩于内支撑处产生弯矩突变,位于基坑底面偏上处;2种土体本构模型计算出的弯矩值及分布形式相差不大。当基坑支护有两道内支撑时,第一道支撑轴力先增后减;第二道支撑在安装后,轴力逐步增大,逐渐成为主受力支撑。

Taking a foundation pit of autility tunnel as an example,the finite element software was used to simulate the stress of the foundation pit supporting structure based on the HSS model,and explore the law of internal force development and deformation development of the foundation pit.The results showed that under the influence of the stiffness of supporting structures,the overall deformation of retaining piles changed from cantilever type to inner convex type with the increase of excavation depth.The maximum horizontal displacement of piles was located near the bottom of the foundation pit.Compared with the HSS model,the horizontal displacement at the bottom of the pile calculated by the MC model was larger,which was about 1.60 times that of the former.The surface settlement curve was parabolic distribution.The maximum settlement occurred at about 10m from the foundation pit.Based on MC model,the large uplift of soil occurred at the edge of the foundation pit.the bending moment of steel sheet pile at the internal support changed suddenly,which was located above the bottom of the foundation pit.Bending moment value and distribution form calculated by two soil constitutive models were similar.When the foundation pit had two internal supports,the axial force of the first support first increased and then decreased;After the second support was installed,the axial force gradually increased and becomed the main bearing support.