青海八大山滑坡群形成机制及稳定性评价研究
摘要
在对青海八大山滑坡群进行现场勘查、室内试验和相关论证的基础上,阐述该滑坡群的基本特征和形成机制,并运用极限平衡分析法和数值模拟对该滑坡群在预设不同工况下的稳定性进行计算和评价;同时,对与750kV官亭—兰州东输电线路塔基稳定性关系密切的滑坡H3,H4,H5进行重点研究。研究结果表明,天然状态下,滑坡H3,H4,H5的整体稳定性系数均大于1.10,处于基本稳定及稳定状态,该状态下的20#,21#,22#塔基稳定性可满足要求;在暴雨工况下,滑坡H3的稳定性系数略小于1.05,处于欠稳定状态,滑坡H4处于基本稳定状态,而滑坡H5仍然处于稳定状态。受此影响,20#塔基安全性受到威胁,而21#,22#塔基仍可满足稳定要求;在烈度为VII度地震状态下,滑坡H3,H4,H5的稳定性系数均小于1.0,处于不稳定状态,20#,21#,22#塔基的稳定性也因此而无法得到保障。此外,敏感性分析结果表明,滑体内摩擦角是影响滑坡群稳定性的最敏感因素。最后,基于滑坡形成机制和定量评价结果,提出为提高滑坡稳定性应采取的工程加固措施,为输电线路的安全运行提供了物质保障,具有较高的实践和理论意义。
Based on field investigation,indoor test and related studies of Badashan landslide group,the basic characteristics and formation mechanism are elaborated. According to different presupposed working conditions, the stability is calculated and evaluated by adopting limit equilibrium analysis method and numerical simulation. At the same time,landslides H3,H4 and H5,which are closely related with tower ground stability of 750 kV transmission line from Guanting to Lanzhou are mainly considered. The results show that coefficients of integral stability of landslides H3,H4 and H5 are all greater than 1.10,and therefore these landslides are under steady state in natural state. As a result,stabilities of towers No.20,21 and 22 can be satisfied. Under rainstorm state,stability coefficient of landslide H3 is slightly less than 1.05 and therefore it is under metastable state. In addition, landslides H4 and H5 are under stable state. As a result,stabilities of towers No.21,22 except for 20 can besatisfied. Under seismic loading with magnitude VIII,stability coefficients of landslides H3,H4 and H5 are all less than 1.0 and therefore they are unstable. As a result,stabilities of towers No.20,21 and 22 can not be satisfied. What′s more,sensibility analysis of stability influencing parameters on landslides H3,H4 and H5 is carried out. The analytical result shows that internal friction angle of landslide mass is the most sensitive factor that influences the landslide stability. Finally,relevant engineering strengthening measures are provided based on formation mechanism;and quantitative evaluation results of the landslides group to guarantee safe operation of the transmission line are presented. Therefore,the results are of great significance in practice.
Based on field investigation,indoor test and related studies of Badashan landslide group,the basic characteristics and formation mechanism are elaborated. According to different presupposed working conditions, the stability is calculated and evaluated by adopting limit equilibrium analysis method and numerical simulation. At the same time,landslides H3,H4 and H5,which are closely related with tower ground stability of 750 kV transmission line from Guanting to Lanzhou are mainly considered. The results show that coefficients of integral stability of landslides H3,H4 and H5 are all greater than 1.10,and therefore these landslides are under steady state in natural state. As a result,stabilities of towers No.20,21 and 22 can be satisfied. Under rainstorm state,stability coefficient of landslide H3 is slightly less than 1.05 and therefore it is under metastable state. In addition, landslides H4 and H5 are under stable state. As a result,stabilities of towers No.21,22 except for 20 can besatisfied. Under seismic loading with magnitude VIII,stability coefficients of landslides H3,H4 and H5 are all less than 1.0 and therefore they are unstable. As a result,stabilities of towers No.20,21 and 22 can not be satisfied. What′s more,sensibility analysis of stability influencing parameters on landslides H3,H4 and H5 is carried out. The analytical result shows that internal friction angle of landslide mass is the most sensitive factor that influences the landslide stability. Finally,relevant engineering strengthening measures are provided based on formation mechanism;and quantitative evaluation results of the landslides group to guarantee safe operation of the transmission line are presented. Therefore,the results are of great significance in practice.
引文
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[11]Itasca Consulting Group Inc..User′s manual(version3.0)of FLAC3D[R].[S.l.]:Itasca Consulting Group Inc.,2005.
[2]王家鼎,惠泱河.黄土地区灌溉水诱发滑坡群的研究[J].地理科学,2002,22(3):305–310.(WANG Jiading,HUI Yanghe.Landslides in crows induced by irrigated water in loess area[J].Scientia Geographica Sinica,2002,22(3):305–310.(in Chinese))
[3]王家鼎.高速黄土滑坡的一种机制——饱和黄土蠕动液化[J].地质论评,1992,38(6):532–538.(WANG Jiading.A mechanism of high-speed loess landslides—saturated loess creeping liquefaction[J].Geological Review,1992,38(6):532–538.(in Chinese))
[4]蒋定生,李新华,范兴科,等.黄土高原土壤崩解速率变化规律及影响因素研究[J].水土保持通报,1995,15(3):20–27.(JIANG Dingsheng,LI Xinhua,FAN Xingke,et al.Research on the law of soil disintegration rate change and its effect factors on the loess plateau[J].Bulletin of Soil and Water Conservation,1995,15(3):20–27.(in Chinese))
[5]张萍,田斌.滑坡稳定性评价研究进展[J].三峡大学学报(自然科学版),2004,26(3):254–257.(ZHANG Ping,TIAN Bin.Research advance of evaluation of landslide stability[J].Journal of China Three Gorges University(Natural Sciences),2004,26(3):254–257.(in Chinese))
[6]SCHUSTER R L,KRIZEK R J.Landslides analysis and control[M].Washington,D.C.:National Academy of Sciences,1978:186–187.
[7]张均锋.三维简化Janbu法分析边坡稳定性的扩展[J].岩石力学与工程学报,2004,23(17):2876–2881.(ZHANG Junfeng.Extension of three-dimensional simplified Janbu′s method for slope stability analysis[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(17):2876–2881.(in Chinese))
[8]陈祖煜.土质边坡稳定分析——原理·方法·程序[M].北京:中国水利水电出版社,2003.(CHEN Zuyu.Soil slope stability analysis—theory,methods and programs[M].Beijing:China Water Power Press,2003.(in Chinese))
[9]BISHOP A W.The use of the slip circle in the stability analysis of slopes[J].Geotechnique,1955,5(1):7–l7.
[10]程谦恭,彭建兵.高速岩质滑坡动力学[M].成都:西南交通大学出版社,1999:85–86.(CHENG Qiangong,PENG Jianbing.Dynamics for high-speed rocky landslide[M].Chengdu:Southwest Jiaotong University Press,1999:85–86.(in Chinese))
[11]Itasca Consulting Group Inc..User′s manual(version3.0)of FLAC3D[R].[S.l.]:Itasca Consulting Group Inc.,2005.
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