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多年冻土空间异质性和边界条件及土性参数的可变性,往往会导致了冻土变化预测的不确定性,全球气候变暖更加剧这一过程.以青藏高原沱沱河地区试验段冻土融化深度预测为例,提出了在全球气候变暖条件下,基于参数服从某一概率分布的确定性模型的概率分析方法,基于此方法进行了融化深度的概率预测.由含水量、干容重的概率分布和20组ATI(空气融化指数)可能值,经蒙特卡罗技术同Stefan公式应用模拟得到了未来100a内天然冻土融化深度,并得到失效概率曲线.结果表明:土体性质的不确定性和温度的可变性导致了冻土变化预测很大的不确定性,概率分析相比于传统确定性分析更加符合实际.在冻土区工程建设中设定冻土融深时,运用概率分析的方法预测融深相比于确定性分析更加安全.同时,气温持续升高对多年冻土区的基础可靠性有强烈影响,设计时应予以考虑.
The spatial heterogeneity of permafrost and the variability of boundary conditions and soil parameters often lead to the uncertainty of the predictions of permafrost changes and the intensification of global warming.Taking the experimental section of Tuotuohe area on the Qinghai-Tibet Plateau Taking the prediction of thawing depth of permafrost as an example, a probabilistic analysis method based on the deterministic model that obeys a certain probability distribution under the condition of global warming is proposed, and the probability of thawing depth is predicted based on this method. The probability distribution of bulk density and the possible values of ATI (air-melting index) of 20 groups, the melting depth of natural frozen soil in the next 100 years was simulated by Monte Carlo technique and the Stefan formula, and the failure probability curve was obtained. The results showed that: Uncertainty and variability of temperature lead to great uncertainty in predicting changes in permafrost. Probabilistic analysis is more realistic than traditional deterministic analysis. When setting permafrost depth in the construction of permafrost regions, Probabilistic analysis predicts thawing depth is safer than deterministic analysis, and the continuing increase in temperature has a strong effect on the basic reliability of the permafrost area and should be considered in design .