围岩特性与衬砌厚度对隧洞衬砌混凝土温度应力的影响

为探明围岩特性与衬砌厚度对衬砌混凝土温度应力的影响,从而制定合理的温控标准,提出了技术可行、经济合理的温控措施,确保了白鹤滩水电站泄洪洞衬砌混凝土具有较高的抗裂安全性。根据白鹤滩水电站泄洪洞衬砌混凝土的结构和材料特性以及边界条件,利用ANSYS对衬砌施工过程中的温度场和应力场进行三维计算。结果表明:衬砌厚度越大,混凝土温度越高,最高温度出现时间越晚;围岩强度越高,衬砌厚度越大,产生的拉应力就越大;而围岩强度越差,衬砌厚度越大,对应的拉应力相对较小。围岩特性与衬砌厚度共同影响着衬砌混凝土温度和温度应力变化趋势,因此,为确保混凝土抗裂安全性,对不同围岩特性的地段应选择不同的衬砌厚度。研究结果可供类似工程参考。

Impacts of Surrounding Rock Behavior and Lining Thickness on Thermal Stress of Lining Concrete in Tunnel

In order to reduce cracks in the lining concrete of spillway tunnel of Baihetan power station, we discuss the impacts of surrounding rock behavior and lining thickness on thermal stress of lining concrete. On this basis, we make reasonable criteria of temperature control and put forward economical and feasible measures. According to the structure and material properties of lining concrete of the spillway tunnel as well as boundary conditions, we carry out three-dimensional simulation on temperature field and stress field during the construction of lining by using ANSYS. Results show that the larger the thickness of lining concrete is, the higher the concrete temperature is, and the later the maximum temperature comes; moreover, the higher the strength of surrounding rock is, and the larger the thickness of lining concrete is, the higher induced tensile stress is, and the reverse is true. Both surrounding rock behavior and lining thickness have effects on the temperature and thermal stress of lining concrete, so it is necessary to determine lining thickness according to surrounding rock behavior to ensure lining concrete safety on resisting cracks.