高地温隧洞温度场三维数值模拟分析

在高地温条件下,温度场是影响引水隧洞结构稳定的重要因素。为了研究不同工况下引水隧洞的温度场特性,以新疆布仑口—公格尔水电站高地温引水隧洞为依托,采用有限元仿真模拟的方法建立三维模型,对不同工况下高地温引水隧洞围岩及衬砌结构的稳态温度场特性进行了模拟计算,并取衬砌结构及围岩不同测点的温度场特性值进行对比分析。结果显示:受洞口及掌子面影响,围岩及衬砌温度随洞深增大可分为平缓段和骤升段两个阶段,且呈非线性变化。衬砌腰拱与顶拱内表面温差随洞深增大逐渐减小,且与工况有关,施工期最大值为1.26℃,运行期最大值为0.22℃。从模拟结果与实测结果的对比分析可知,实测与模拟所得围岩温度场分布特性相同。研究成果可为高地温引水隧洞热力耦合分析及其洞室稳定性提供了理论依据,同时也可为高地温区相关工程提供参考。

3-D numerical simulation analysis on temperature field of tunnel under high ground temperature

Under the condition of high ground temperature, temperature field is an important factor that impacts the structural stability of water diversion tunnel. In order to study the characteristics of the temperature field of water diversion tunnel under various working conditions, the characteristics of the static temperature fields of both the surrounding rock and the lining structures of water diversion tunnel with high ground temperature under various working conditions are simulatively calculated with a 3-D model established with the method of finite element simulation by taking the water diversion tunnel under high ground temperature of a hydropower station in Xinjiang as the basis, and then the characteristic values of the temperature fields taken from various observing points of both the lining structure and the surrounding rock are comparatively analyzed. The result shows that impacted by both the tunnel entrance and the working face, the increases of the temperatures of the surrounding rock and the lining along with the increase of the tunnel depth can be divided into two phases, i. e. gentle and sudden rising, with non-linear changes.The surface temperature differences at the arch waist and the lining gradually decreased along with the increase of the tunnel depth, which are related to the working condition, for which the maximum value during the construction period is 1. 26 ℃ and is0. 22 ℃ during the operation period. It is known from the comparative analysis made on the simulation result and the observed result that the characteristics of the surrounding rock temperature field distribution from both the observation and the simulation are same. The study result can not only provide a theoretical basis for the coupled thermo-mechanical analysis on the water diversion tunnel under high ground temperature and the stability of its cavern, but can also provide a reference for the relevant construction projects in high ground temperature regions.