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为得到多年冻土区公路隧道围岩温度场和融化圈的发展规律,建立了围岩融化圈的计算方法,对融化圈深度和围岩温度的计算值与实测值进行了对比,采用有限元法分析了支护对融化圈的影响。分析结果表明:围岩温度平均误差不超过0.6℃,融化圈深度误差不超过10%,计算值与实测值吻合较好;每延迟1d施作喷射混凝土,融化圈深度增大10cm,喷射混凝土厚度每增加5cm,融化圈深度增加约10cm;一次模筑混凝土入模温度为15℃时的融化圈深度比入模温度为5℃时大了约10cm;当保温板厚度从5cm增加到20cm时,融化圈深度减小2/3,保温板及二次模筑混凝土水化热对融化圈深度有较大影响;洞内风速为3.0 m·s~(-1)时的融化圈深度比洞内风速为1.0m·s~(-1)时减小了10~20cm;施作喷射混凝土30、60、90、120d后,洞内气温为8℃时的融化圈深度为洞内气温为2℃时的1.25、1.31、1.35、1.40倍。可见,洞内气温宜控制在3℃~5℃,围岩开挖后应尽早施作支护,宜选用低热或中热水泥以降低混凝土释放的水化热。
In order to get the law of temperature field and melting circle of surrounding rock in permafrost region, the calculation method of surrounding rock melting circle was established. The calculated value and measured value of melting zone depth and surrounding rock temperature were compared. Analysis of the impact of support on the melting circle. The results show that the average temperature error of surrounding rock does not exceed 0.6 ℃, the depth error of melting circle does not exceed 10%, and the calculated value agrees well with the measured value. When the sprayed concrete is delayed by 1d, the depth of melt ring increases by 10cm, For each increase of 5cm, the depth of the melting circle increased by about 10cm. When the temperature of the mold-forming concrete was 15 ℃, the melt ring depth was about 10cm larger than that of the mold temperature of 5 ℃. When the thickness of the insulation board increased from 5cm to 20cm, The depth of the melt ring is reduced by 2/3, the heat of the insulation board and the secondary mold concrete hydration heat have a greater impact on the depth of the melt ring; the depth of melt ring when the wind speed is 3.0 m · s ~ (-1) When the wind speed is 1.0m · s -1, it decreases by 10 ~ 20cm. After the sprayed concrete is applied for 30, 60, 90 and 120d, the depth of the melt ring at the temperature of 8 ℃ is 2 ℃ At 1.25, 1.31, 1.35, 1.40 times. Can be seen that the temperature inside the cave should be controlled at 3 ℃ ~ 5 ℃, rock excavation should be implemented as soon as possible after the support should be selected low heat or moderate heat cement to reduce the heat of hydration concrete release.