超长混凝土地下室墙体中预应力作用计算与分析

Calculation and analysis on prestressing action of the super-long concrete underground wall

超长混凝土墙体在降温、收缩等过程中,温度收缩应力超过混凝土的抗拉强度是引起墙体开裂的重要原因。以"地基上的长墙"作为计算模型,利用温度应力和预压应力在离开端部较远处为均布应力的假定,推导了预应力与温度、混凝土收缩共同作用下的墙体中应力计算公式。并用有限元软件ABAQUS进行了大量计算,验证了理论公式的可靠性和精确性。在应力计算公式的基础上,用极限变形的概念推导了裂缝间距的计算公式,此间距可作为施工缝和后浇带间距的计算依据。最后,根据后浇带的间距计算得到了一般情况下预应力筋的合理分段长度,可为今后超长混凝土墙体结构的理论分析和工程实践提供参考。

In the process of cooling and shrinkage,temperature shrinkage stress of super-long concrete wall exceeding the tensile strength of concrete becomes an important reason for the cracking of the wall. ＂The long wall on the foundation＂was taken as a model,it was also assumed that the temperature stress and pressure stress far from the ends are uniform stresses,then,wall stress calculation formula was deduced under the combined action of the prestress,temperature and concrete shrinkage. The finite element software ABAQUS was used to conduct a large number of calculations to verify the reliability and accuracy of the theoretical formula. Based on the formula of stress calculation,the calculation formula of crack spacing was derived by using the concept of limit deformation,further the spacing of construction joint or post casting strip could be calculated. Finally,according to the spacing calculation of the post casting strip,the reasonable subsection length of the pre-stressed reinforcement was obtained for general condition. It can provide reference for the theoretical analysis and engineering practice of the super-long concrete wall structures in the future.