混凝土板下部土拱形成规律研究

Numerical research of soil arching effect under concrete pavement

土拱效应是岩土工程中的常见现象,地下穿越施工过程中开挖断面上部土体相互挤密,引起地层不均匀沉陷,在洞顶局部区域形成土拱.当表层存在刚性混凝土面板时,可对地表变形产生约束,改变原有应力传递路径和土拱影响范围.对此,采用ABAQUS有限元软件建立仿真分析模型,针对不同板厚、埋深和管径条件下的土拱形成规律进行研究,探讨地基沉陷与管顶覆土压力分布特征.研究结果表明,土拱效应导致地基内部主应力方向发生偏转,管顶两侧竖向应力有明显增加,刚性道面板板底未发生隆起变形,开挖断面覆跨比指标不是评价土拱效应的唯一指标,需结合具体参数条件进行讨论.

Soil arching effect （SAE） is a common phenomenon in geotechnical engineering. Since the foundation soil around excavation section is compacted during underground construction, soil arch will be generated at the top of cave accompanied by settlement and upheaval deformation of ground surface. Due to the existence of rigid concrete pavement, the surface deformation will be constrained which may affect the load transfer path and the level of SAE. In this paper, a numerical modal is established based on ABAQUS software. The rule of SAE with different pavement thickness, burial depth and pipe diameter are analyzed. The distribution of foundation displacement and overburden pressure are examined and compared. Research results indicated that SAE may alter the direction of max principle stress of foundation soil and increase the vertical stresses on the both two flanks of pipe crown. No upheaval deformation can be found at the bottom of pavement structure. The depth-span ratio of foundation soil above the excavation section may not be the only index to evaluate SAE, which is necessary to be discussed under specific parameter conditions.