Study On The Development Law Of Temperature Field Of The New The Freeze-Sealing Pipe Roof Under Seepage Condition

The new pipe curtain freeze technique utilizes the benefits of pipe curtain technique and freeze technique and is applied to some advanced geologic environments.However,there square measure few studies on the new pipe curtain freeze technique below flow conditions.supported the particular project of Gongbei Tunnel of Hong Kong-ZhuhaiMacao Bridge,this paper establishes a numerical model of pipe curtain freeze of Gongbei Tunnel below flow conditions and calculates it.The pertinency of the model is verified by examination the numerical simulation analysis results with the measured knowledge of Gongbei Tunnel.The temperature field variation law of the pipe curtain freeze technique of Gongbei Tunnel below flow conditions is analyzed.The influence of groundwater flow on the pipe curtain freeze technique of Gongbei Tunnel is analyzed by symmetrical points.Then,per the pertinency of COMSOL numerical simulation technique,the numerical geometric model of the new pipe roof freeze technique below flow condition is established on the premise of the pipe roof freeze model of Gongbei tunnel.The temperature field variation law of the new pipe roof freeze technique below flow condition is studied by analyzing the cloud and isogram changes of various sections.Finally,the influence of various factors on the temperature field of the new pipe roof freeze technique below flow condition is studied.Finally,per the results of single issue influence,completely different optimisation schemes square measure planned,and also the freeze impact of the new pipe curtain freeze technique before and when optimisation is compared.the most conclusions square measure as follows :(1)By comparing the measured data and numerical simulation results of Gongbei tunnel tube curtain freezing method,the cooling curve of the two is not much different,and the temperature difference in the freezing process is about 2°C,so the correctness of the hydrothermal coupling model can be verified.(2)The formation of frozen soil curtain will hinder the flow of groundwater.There is no groundwater flow in the area enclosed by the pipe curtain freezing method,and groundwater will flow around the frozen soil curtain.By analyzing the cooling curves of temperature measurement points in different paths,it is found that groundwater has a great influence on the water surface,and the frozen soil curtains of the four paths are all greater than 3m,which meets the requirements of construction excavation.(3)The new pipe curtain freezing method will intercept the flow of groundwater after the formation of the frozen soil curtain,and weaken the flow velocity of the water surface.At the same time,the groundwater flow causes the temperature change of the temperature measurement point at the symmetrical position of the upper and lower reaches of the freezing pipe to be inconsistent,and the final freezing temperature is different.At the same time,the farther the monitoring point is from the freezing pipe,the greater the influence of groundwater flow.The larger the seepage velocity is,the longer the intersection time of frozen soil curtain is.When the seepage velocity is greater than 4.27m/d,the intersection time of frozen soil curtain increases explosively.When the seepage velocity reaches5.27m/d,the frozen soil curtain begins to not close.When the initial temperature is higher,the time of forming the frozen soil curtain is also increasing,and the final temperature of the frozen soil curtain is higher.With the increase of salt content,the average temperature of frozen soil curtain formed by the new pipe curtain freezing method under seepage condition also increases.(4)According to the influence of seepage velocity on the new pipe curtain freezing method,different numbers of freezing pipes are added to the water surface of the new pipe curtain structure.Three different optimization schemes are set up and numerical simulation is carried out.The following results are obtained : In the original scheme,when the seepage velocity is 4.27 m/d,the time of the frozen soil curtain is 83 d,and the thickness of the frozen soil curtain is 4.08 m;after the optimization of the first scheme,the intersection time is shortened to 60 days,and the thickness of the frozen soil curtain is 4.35 m,an increase of0.27 m.After the optimization of the second scheme,the intersection time of the frozen soil curtain is shortened to 47 days,and the thickness of the frozen soil curtain is increased by0.16 m.After the optimization of scheme three,the intersection time of frozen soil curtain is shortened to 43 days,and the thickness of frozen soil curtain is increased by 0.62 m.After the optimization of the scheme,the time of forming the frozen soil curtain by the new pipe curtain freezing method under the seepage condition is reduced,and the thickness is also increased.After data comparison,the optimization effect of scheme three is better than that of scheme two,and scheme one has the smallest optimization effect.