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以G214公路高原多年冻土区姜路岭隧道浅埋段热棒群防护工程为例,通过对隧道天然工况下和热棒群防护下的隧道围岩地温变化特征及冻融圈变化规律的研究,评价了利用热棒群对高原多年冻土区隧道浅埋段进行主动热防护的工程效果。研究表明:天然工况下隧道施工产生的冻融圈范围大于2.2 m;冻融圈回冻时间大于4 a;在热棒群防护下姜路岭隧道出口左洞洞侧人为冻土上限抬高0.5 m;隧道洞顶冻融圈的回冻时间为1 a,洞侧冻融圈回冻时间为2~3 a;地温总体上呈现出类似于正余弦曲线的变化形式,暖季地温较大,寒季地温相对较小,且随着时间推移,同期地温在逐渐降低;评价认为利用热棒群对多年冻土区隧道浅埋段进行主动热防护可以快速消除施工给隧道冻土围岩带来的热干扰,维持洞周冻土围岩的稳定,同时在洞周形成冻土防渗帷幕,阻隔冻结层上水向隧道结构方向的渗入,是一种有效保护隧道多年冻土环境的工程措施。
Taking the hot rod group protection project of shallow section of Jiangliling tunnel in permafrost zone of G214 plateau as an example, through the study of the change characteristics of the surrounding rock temperature and the variation law of the freezing and thawing ring under the tunnel natural conditions and the hot rod group protection, The effect of active thermal protection on shallow sections of tunnels in permafrost regions of the plateau was evaluated using hot sticks. The results show that the range of the freezing and thawing ring produced by tunnel construction is greater than 2.2 m under natural conditions and the thawing time of the freezing and thawing ring is more than 4 a. Under the protection of hot rod group, The thawing time of tunnel freezing and thawing ring was 1 a, and the time of thawing and thawing was about 2 ~ 3 a on the tunnel side. The geothermal temperature generally showed a variation similar to the sine and cosine curves. The seasonal temperature is relatively small, and with the passage of time, the geothermal temperature is gradually reduced over the same period; evaluation that the use of hot rod group of permafrost tunnel shallow buried active thermal protection can quickly eliminate the construction of tunnel permafrost caused by rock Thermal interference to maintain the stability of the surrounding rock permafrost in the tunnel, while the formation of permafrost in the hole around the curtain to block the frozen layer of water infiltration into the direction of the tunnel structure is an effective measure to protect the permafrost tunnel environment engineering measures.