超深基坑混凝土环梁及内衬浇筑温度效应研究

Research on Temperature Effect of Pouring Concrete Ring Beam and Lining in Super Deep Foundation Excavation

采用有限元分析模型对基坑环梁浇筑过程中的温度场进行了简化分析,通过与实测数据对比验证了模型的可靠性,并对相关参数进行了分析,进一步对内衬墙浇筑过程进行模拟,分析内衬混凝土水化放热升温以及后续的降温过程对已建地下连续墙的影响。研究表明,环形混凝土结构构件在浇筑后的降温过程以及温差影响下易产生残余温度应力和应变,生成温度裂缝;影响这种温度应力的主要因素包括混凝土自身的膨胀特性和变化温度场。同时,基坑内部环形支撑的浇筑会对已建的地下连续墙传递热量,引起局部地下连续墙的温度应力,具体表现为内衬浇筑区域一定纵向范围内,地下连续墙迎坑侧环向和竖向产生压应力,近地下连续墙侧环向和竖向均产生拉应力,且近地下连续墙侧的拉应力增长幅度显著小于迎坑侧的压应力增长。

In this paper, the finite element analysis model is used to simplify the analysis of the temperature field during the pouring process of the ring beam of the foundation excavation, and the reliability of the model is verified by the comparison and analysis of the measured data. Furthermore, the pouring process of the lining wall is simulated, and the influence of the hydration and exothermic heating of the lining concrete and the subsequent cooling process on the diaphragm wall is analyzed. The results show that the ring-shaped concrete structure members are prone to produce residual temperature stress and strain and temperature cracks during the cooling process after pouring and under the influence of temperature difference. At the same time, the pouring of ring support inside the foundation excavation will transfer heat to the built diaphragm wall and cause the temperature stress of local ground wall, which is specifically manifested in the longitudinal range of lining pouring area, the side facing the pit of diaphragm wall the ring and vertical compressive stress is produced, and the tensile stress is produced in the circumferential and vertical direction near the ground wall, and the increase range of the tensile stress near the ground wall is significantly less than that of the side facing the pit. At the same time, the numerical simulation results show that the tensile stress region will occur outside a certain longitudinal range of the inner lining pouring area.