帕隆藏布流域冰碛物斜坡结构及稳定性评价方法
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摘要
帕隆藏布流域是我国海洋性冰川最重要的发育区,大量的冰碛物形成了数量众多的松散堆积体,孕育着密集的地质灾害。通过大量案例调查及现场测试工作,总结出冰碛物堆积体斜坡3种不同的斜坡结构及其可能发生的破坏方式,包括浅表冰碛层降雨蠕滑型、较厚冲洪积物覆于冰碛层之上的水岩作用控制型以及冰碛层夹湖相沉积差异风化型。针对研究区最常见的浅层破坏模式,以测窗法面含石率及泥沙含量来描述宽级配特征,以超重型动力触探锤击数表示固结程度,以坡长与高度对数比表示地形要素,考虑植被覆盖及松散层厚度影响,采用最小二乘曲线拟合,建立并验证了稳定性计算公式。通过对公式的实用化进行探索,得到不同冰碛物斜坡高度所对应的坡度值,当冰碛物斜坡高度小于10 m时,坡度可达70°以上。
The Parlung Zangbo River Basin is the largest region of oceanic glaciers in China,where a large amount of moraine form substantial loose deposits and numerous geological hazards develop. Through a lot of case investigation and field tests,three different slope structures of moraine deposits and their possible failure modes are summarized,i. e.,the rainfall-caused creep failure of shallow moraine,the water-rock interaction controlling failure of moraine layer covered with thicker alluvial deposits,differential weathering failure of moraine layer intermingled with lake deposits. In view of the shallow failure mode,most common shallow in the study area,the characteristics of wide gradation are described by the stone content and sediment content in per unit area by sampling window method,the consolidation degree is expressed by the hamming number of super-heavy dynamic penetration test,and the topographic elements are represented by the logarithmic ratio of slope length to height,so the stability calculation formula is established and verified by the least square curve with the consideration on the influence of vegetation cover and loose layer thickness. By practicality analysis of the formula,the slope values corresponding to the different moraine slope height are obtained. When the moraine slope height is less than 10 m,the slope can reach more than 70 °.
The Parlung Zangbo River Basin is the largest region of oceanic glaciers in China,where a large amount of moraine form substantial loose deposits and numerous geological hazards develop. Through a lot of case investigation and field tests,three different slope structures of moraine deposits and their possible failure modes are summarized,i. e.,the rainfall-caused creep failure of shallow moraine,the water-rock interaction controlling failure of moraine layer covered with thicker alluvial deposits,differential weathering failure of moraine layer intermingled with lake deposits. In view of the shallow failure mode,most common shallow in the study area,the characteristics of wide gradation are described by the stone content and sediment content in per unit area by sampling window method,the consolidation degree is expressed by the hamming number of super-heavy dynamic penetration test,and the topographic elements are represented by the logarithmic ratio of slope length to height,so the stability calculation formula is established and verified by the least square curve with the consideration on the influence of vegetation cover and loose layer thickness. By practicality analysis of the formula,the slope values corresponding to the different moraine slope height are obtained. When the moraine slope height is less than 10 m,the slope can reach more than 70 °.
引文
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[2]尚彦军,杨志法,廖秋林.雅鲁藏布江大拐弯北段地质灾害分布规律及防治对策[J].中国地质灾害与防治学报,2001,12(4):31-40.
[3]袁广祥,丁仁伟,尚彦军,等.川藏公路帕隆藏布段沿线第四纪堆积体的成因及其分布规律[J].地质与勘探,2012,48(1):170-176.
[4]曾庆利,杨志法.川藏公路102滑坡群地段基覆界面问题研究[J].水文地质工程地质,2008,35(3):1-6.
[5]袁广祥,曾庆利,尚彦军.川藏公路然乌—鲁朗段冰碛高边坡稳定性分析[J].中国地质灾害与防治学报,2001,12(4):31-35.
[6]张惠霞,郑书彦.帕隆藏布滑坡侵蚀特征及稳定性分析[J].公路,2004(9):90-92.
[7]陈仁容,周尚哲.末次冰期冰碛垄系列的形态特征及其形成探讨—以帕隆藏布江谷地为例[J].冰川冻土,2012,34(4):837-846.
[8]丁继新,周圣华,杨志法.川藏公路南线然乌—鲁朗段工程地质分区[J].自然灾害学报,2005,14(5):155-160.
[9]徐鼎平.某露天铁矿冰碛土台阶边坡可靠性[J].岩土工程技术,2007,21(1):12-14.
[10]徐鼎平,汪斌,江龙剑,等.冰碛土三轴数值模拟试验方法探讨[J].岩土力学,2008,29(12):3467-3480.
[11]李骅锦,冯文凯,许强,等.四川理县小歧村冰碛物角砾土抗剪强度特性研究[J].人民长江,2015,46(12):38-41.
[12]冯俊德,李建国,汪稔.云南某铁路冰碛土大型直剪强度特性试验研究[J].岩土力学,2008,29(12):3206-3210.
[13]木勋,马伟杰,刘宏.西南某机场冰碛土工程特性研究[J].水利科技与经济,2016,22(1):18-20.
[14]吕士展,汪稔,胡明鉴,等.玉龙雪山西麓原状冰碛土CT扫描试验研究[J].岩土力学,2014,35(6):1594-1598.
[15]谢春庆.川西冰碛层工程勘察方法研究[J].勘察科学技术,2002(5):16-19.
[16]刘昌.西藏巴河冰碛物的工程特性[J].水力发电,1998(8):14-16.
[17]尼伧娜.浅析波堆水电站坝址区及其工程右岸冰碛物的形成特性[J].西藏科技,2014(7):71-74.(编辑:刘媛)