暗涵墙体混凝土温度场与应力场仿真分析

为了研究暗涵墙体施工早期混凝土的开裂情况,从混凝土温度变形出发,对暗涵中墙裂缝成因进行了分析。根据稳态温度场理论,采用ANSYS有限元分析软件,混凝土热单元类型选用solid70,建立了求解中墙温度场的三维实体模型,研究了不同工况组合下的暗涵墙体温度场分布规律。根据暗涵墙体混凝土温度场进行温度应力的仿真,研究了暗涵中墙混凝土温度应力分布及变化规律。结果表明:暗涵中墙内外表面的压应力近似相等,与温度呈线性关系,中墙内外表面不存在拉应力;暗涵中墙中间截面的压应力与温度差成反比,而拉应力与温差近似成正比;最大拉应力为1.92 MPa,出现在中墙中间截面,其值在混凝土的抗拉强度范围内,故中墙几乎不会开裂。通过设置合理的边界条件与环境条件,可为相关混凝土施工温度裂缝控制提供参考依据。

Simulative analysis on temperature field and stress field of concrete for buried culvert wall

In order to study the cracking of the concrete for the wall body of buried culvert during the early stage of construction, the causation of the crack occurred at the middle wall of the buried culvert is analyzed from the aspect of the temperature deformation of the concrete. According to the theory of steady-state temperature field, a 3-D entity model for deriving the temperature field of the middle wall is established with the finite element analysis software-ANSYS, for which solid 70 is selected for the thermal element of the concrete, and then the laws of the temperature field distributions for the wall body of the buried culvert under various combinations of working conditions are explicated. Furthermore, the temperature stress distribution of the concrete for the middle wall of the buried culvert and its changing law are studied in accordance with the temperature simulation made on the temperature field of the concrete for the culvert wall. The result shows that the inner and outer surface compressive stresses of the middle wall of the buried culvert are approximately equal and linearly related to temperature, while no any tensile stresses are there on both the inner and the outer surfaces of the middle wall. The compressive stress on the intermediate cross-section of the middle wall of the buried culvert is inversely proportional to the temperature difference, while the tensile stress is proportional to the temperature difference. The maximum tensile stress is 1. 92 MPa and occurs at the intermediate cross-section of the middle wall, of which the value is within the tensile strength of the concrete, thus the middle wall is almost not to be cracked. Through setting up reasonable boundary conditions and environmental conditions for guiding the layout of temperature monitoring points, a reference basis can be provided for the temperature crack control during the relevant concrete construction.