青藏公路多年冻土区路基病害易发性概率模型

Probability model for subgrade hazards susceptibility of Qinghai-Tibet Highway in permafrost regions

为研究青藏公路多年冻土区路基病害的分布规律,探究路基病害与其影响因素之间的相互关系,定量计算各因子对路基病害的影响权重,最终达到预测路基病害易发性概率的目的,以青藏公路西大滩至唐古拉山约470km范围内多年冻土段作为评价路段,选取体积含冰量、年平均地表温度、路堤高度、路堤走向、天然地表植被覆盖度、地表径流6个影响因子,通过已有图件地理信息提取、路基设计资料数据统计分析以及现场调查的方式,充分收集各因子的原始属性数据。同时,制作评价路段所在工程走廊内的径流分布图,通过图件与实地调查相结合的方式明确径流与公路相交的地点,并获取2014年青藏公路评价路段路基沉降面积的实测资料,以影响因子为自变量,以实测路基病害数据为因变量,引入Logistic模型进行回归分析,建立多年冻土区公路路基病害易发性的概率模型,计算评价路段内每个评价单元的路基病害易发性概率。研究结果表明:该概率模型回归结果的正确率为76.3%;易发性概率小于15%的路段占28.62%,易发性概率大于50%的路段占5.59%;易发性概率高的路段主要位于北麓河至风火山之间(K3064~K3066、K3070~K3071)、风火山至雅玛尔河之间(K3084~K3086)、沱沱河至开心岭之间(K3161~K3165)、开心岭至通天河之间(K3171、K3176~K3182、K3185)、雁石坪至唐古拉山之间(K3246)。

In order to analyze the distribution characteristics of subgrade distresses of the Qinghai-Tibet Highway（QTH）in permafrost regions,explore the relationship between influencing factors and diseases,quantitatively calculate the weight of each factor on diseases and ultimately forecast theprobability of susceptibility of subgrade diseases,this paper selected permafrost sections in the range of about 470 km along the QTH from Xidatan to Tanggula Mountain as evaluation section.Six factors were selected as influence factors, which were volumetric ice content,annual mean ground surface temperature,embankment height,embankment trend,vegetation coverage and surface runoff.According to the extraction of geographic information through the existing map,statistical analysis of design data and field investigation,the original data of each factor was adequately collected.Runoff distribution map of the engineering corridor was drawn.The location where runoff intersected with the QTH was checked by field investigation and maps,and the measured data of subgrade settlement of the QTH evaluation section in 2014 were obtained.The Logistic model was introduced to conduct regression analysis,in which influencing factors were set as independent variables and the measured data of subgrade diseases was set as dependent variable.This paper established a probability model for subgrade diseases susceptibility of the QTH in permafrost regions,and calculated the probability of subgrade diseases in each evaluation unit within the evaluation section.The results show that accuracy of the calculation results is 76.3%.Among all the evaluation sections,the sections in which the probability of susceptibility is less than 15% occupies for 28.62%,and the sections in which the probability of susceptibility is larger than 50% occupies for 5.59%.The sections which are the most probable to develop subgrade diseases distribute from Beilu River to Fenghuo Mountain（K3064 to K3066,K3070 to K3071）,Fenghuo Mountain to Yamaer River（K3084 to K3086）,Tuotuo River to Kaixin Mountain（K3161 to K3165）,Kaixin Mountain to Tongtian River（K3171,K3176 to K3182,K3185）,Yanshiping to Tanggula Mountain（K3246）.