2000 年易贡乡扎木弄沟滑坡型泥石流主控因素分析

为进一步查明 2000 年 4 月 9 日扎木弄沟滑坡型泥石流的成因, 有必要分析内外动力条件对该次滑坡型泥石 流的影响。基于1950- 2000 年的地震活动和气温资料, 以及 2000 年 3 月- 4 月的降雨资料, 分析地震活动、冻融循 环和干湿循环与 2000 年滑坡型泥石流的时空耦合关系。结合花岗岩岩体结构特征, 分析内外动力条件对 2000 年 滑坡型泥石流的影响机制。研究结果包括两方面内容: ( 1) 极端的冻融循环、干湿循环和地震活动是 2000 年滑坡型 泥石流的主控因素, 其中灾前 Ms 41 8 的地震是 2000 年滑坡型泥石流形成的直接诱发因素。( 2) 长期的地震活动、 冻融循环和干湿循环增加了向南倾的流域源头花岗岩岩体的脆弱性, 也增加了流域源头岩体地表裂隙, 受后续降水 和冰雪融水渗流的影响, 流域源头岩体饱水强度衰竭, 在 41 8 级地震诱发作用下, BH01 崩滑体发生崩滑, 2000 年滑 坡型泥石流发生。 The landslide2trig g ered debris flow that occurred on April 9th, 2000 ( 2000 LTDF) in Zhamunong g ully had a volume of 3@ 108 m3 . We st udied the effects of inter nal and exter nal dynamic conditio ns o n the cause o f the 2000 LTDF. Based o n the ea rthquake data and temperature data fr om 1995 to 2000 and rainfall data from Mar ch to April 2000, we ana lyzed the spatio2 tempo ral co upling r elatio nship of the 2000 LTDF w ith seismicit y, freeze2thaw cy cle, and dry2w et cy cle. Based o n the structural char acteristics of g ranite r ock, w e analyzed the mechanism o f internal and ex ternal dy namic conditio ns on the cause of the 2000 LT DF. The results included two aspects. Firstly, the main facto rs of the 2000 LTDF wer e long2term fr eeze2thaw cycle, dry2wet cy cle, and seismicity. Earthquake of Ms 4. 8 w as the dir ect inducing facto r of t he 2000 LT DF. Seco ndly , t he long2term effect of seismicity, freeze2thaw cycle, and dry2wet cycle increased the vulnerability as well as t he surface fr act ur e of BH01 gr anite r ock mass. Due to the inf luence of the subsequent seepage of rain and melt water, the strength o f gr anite ro ck mass w as exhaust ed. Under the effect of the Ms 4. 8 earthquake, t he BH01 landslide occurr ed in 2000 and trig ger ed the debris f low 国家自然科学基金( 41861134008; 41661134012; 41671112) ; 四川省安全生产科技项目( aj20170601105926) ; 桥梁无损检测与工程 计算四川省高校重点实验室项目( 2016QYY02) ; 四川理工学院人才引进项目( 2018RCL09)