摘要
西南某水电站块石料场弃渣堆积体边坡于2004年形成,堆积规模约21×10~4 m^3。该边坡前缘未设支挡结构措施,后期受2008年"5.12"汶川特大地震、2013年"4.20"芦山强烈地震影响,以及在降雨作用下,后部推移变形,并严重威胁坡脚居民安全。本文采用现场勘察、原位双环渗透试验等手段,分析了弃渣堆积体边坡的变形破坏机制。结果表明:弃渣体的饱和渗透系数(k)远大于下伏老堆积土体,弃渣体表层k值高达1.41×10^(-1) cm/s,1m深时为2.00×10^(-2) cm/s;老堆积土体表部k值为1.88×10^(-3)cm/s,1m深时为5×10^(-4)cm/s。两者渗透系数的巨大差异,使得弃渣体与下伏老堆积体之间形成富水带,产生较大的孔隙水压力,进而对弃渣堆积体边坡形成浮托力,导致其推移变形。稳定性计算结果显示堆积体稳定性系数随降雨时长的增加而减小,但减小速率逐渐趋于平缓。
A waste slag accumulation slope at a certain hydropower station in southwestern of China was first formed in 2004,and the accumulation size of it is about 21×104 m3.As there was no retaining measures for the front edge of the slope,the rear part of it deformed in the later period under the influence of the devastating earthquake of＂5.12＂Wenchuan in2008 and the strong earthquake in Lushan in 2013,as well as persistent rainfall.And the deformation seriously threaten the safety of residents at the toe of the slope.Geological field work and in-situ double loops infiltration test,etc.are presented to analyze the failure mechanisms of the slope.The result suggests that the saturated permeability coefficient（k）of the waste slag body is much larger than that of the old accumulation body.The kof waste slag body on surface is up to 1.41×10-1 cm/s,while on 1 mdepth is 2.00×10-2 cm/s.The kof old accumulation body on surface only can be 1.88×10-3 cm/s,while on 1 mdepth is 5×10-4 cm/s.The large difference in the permeability of the two causes the formation of a water-rich zone between the waste slag body and the underlying old accumulation body,resul-ting in a large pore water pressure,which in turn creates a floating force on the waste slag accumulation slope,resulting in its deformation.The calculation of the stability shows that the stability coefficient of the slope decreases with the increase of the rainfall duration,but the decrease rate gradually tends to be gentle.
作者
潘一茜
胡卸文
PAN Yi-xi;HU Xie-wen(Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University,Chengdu 610031 ,China;Aseismic Engineering Technology Key Laboratory of Sichuan Province, Southwest Jiaotong University,Chengdu 610031 ,China)
出处
《地质灾害与环境保护》
2018年第2期107-112,共6页
Journal of Geological Hazards and Environment Preservation
关键词
弃渣堆积体
变形破坏机制
渗透系数
降雨
waste slag field
failure mechanisms
hydraulic conductivity
rainfall
