天山北坡乌——库公路沿线自然灾害特征及其对公路的影响

The Characteristics of Natural Disaster and Its Influence on Urumqi-Kuerle Highway,in North Slop of Tianshan Mountain

塌方和泥石流主要集中在海拔1500m以上的中山带,其每年暴发的高峰期同降水的最大期一致,暴发频率与公路两侧山坡的风化程度、碎屑含量、基岩状况及支沟状况有密切关系,热融沉陷发育在冻土区,每年4月冻土开始融化、稀如泥浆,使路面下沉翻浆,其沉陷速度在天山北坡为3.0cm/年,11月冻结,南坡为向阳坡,春季气温回升快,冻土首先沉陷;夏季温度高,季节融化层厚度大;秋季阳坡降温慢,融化层冻结慢,其危害程度取决于季节融化层的厚度,由于老公路修筑在富含冰的新冰碛垄上,原有的稳定结构被破坏,冰体融化造成公路大规模的沉陷和坍塌,公路完好率仅10％～20％。

Highway was often get strong destroy by the various natural disasters in mountain area. Collapse and debris flow concentrate in middle mountain.which elevation is more than 1500 metres. High peak period of their burst is simultaneous with the maximum period of precipitation in every year. Frequency of its burst has close relation with weathering degree, content of debris, condition of bed rock and tributary situation in flank hillside of highway. Thaw sinking developed in frozen regions. Every year frozen ground begin thawing and like slush in April. The road surface is muddy and sink,which rate is 3. 0 cm/yr in north slope of Tianshan. It is frozen in November. The temperature of south slope (the sun-slope) rise quickly in spring and the frozen ground was sinking first. In summer seasonally thawing layer was thicker with higher temperature. The temperature of sun-slope fall slowly in autumn,so ihe thawing layer freeze later. Harm degree of thaw sinking depened on the thick of seasonally thawing layer. Because old highway was built on the new moraine.which has more ice. its original steadiness condition was brokon and the ice thaw. It cause the highway sinking and collapse on a large scale. The intact ratio of highway is only 10—20 percent.