Abstract:
The artificial ground freezing method is characterized by good waterproof, high strength of frozen strata, and strong adaptability to construction layers, which is widely applied in the construction of water-rich formations.However, groundwater seepage has a significant impact on the freezing temperature field.Based on a sequential freezing project of parallel tunnels in Nanchang, in-situ tests on the freezing temperature field were conducted, at the same time a coupled hydraulic-thermal model was established to investigate the influence of groundwater seepage velocity on development of the temperature field.The results show that: ① the measured temperature in each monitoring hole was in agreement with simulated results, verifying effectiveness of the model.② The freezing pipes in the upstream seepage zone reduced the temperature of groundwater.The cold energy was carried downstream with water flow.The formation of the freezing wall on the left-side upstream area reduced the groundwater flow velocity in the right-side downstream strata.③ Local frozen bodies were first formed on the upper, lower, and right sides of the single freezing pipe loop, and it gradually developed until a closing freezing wall was formed on the left side of the pipe loop.④ When the groundwater seepage velocity exceeded 1.0 m/d, the difference of loop-closing time between the left and right lines magnified with the increase of seepage velocity.⑤ For the sequential freezing engineering in strata of groundwater seepage, it is suggested to complete upstream freezing construction first, which can effectively improve construction efficiency.