颗粒组分对泥石流形成形态影响研究  

Influence of Grain Size Distribution on the Formation of Debris Flow

作　　者：周健[1,2] 王连欣[1] 贾敏才[1,2] 李业勋[1] 

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《湖南大学学报（自然科学版）》2014年第1期8-14,共7页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(41272296)

摘　　要：利用自主设计的小比例尺模型槽，采用粗砂（1~2 mm）和细砂（0.075~0.25 mm）按照不同质量比例制作模型，在人工降雨条件下研究了不同的颗粒组分对砂性土泥石流形成形态的影响.模型试验研究发现，随着细砂含量由20%增加至100%，泥石流破坏形态由分级块体滑落向整体流滑型转变.利用GeoDog软件分析位移场，利用孔压计测量孔压变化.研究发现：分级块体滑落破坏过程存在明显的潜在滑动面的发展，孔压随裂缝的产生而耗散、随雨水渗入裂缝而升高，呈波浪式下降；整体流滑型突发性强，破坏前没有明显滑动面出现，孔压呈一次性陡降.通过测定启动过程单位时间启动量发现，流滑型破坏单位时间启动量大于分级块体滑落型.分层块体滑落形成机理为土体渗透系数大，雨水快速渗透破坏坡脚，使上部土体失去支撑而分层坍塌；流滑型破坏机理为土体渗透系数小，后部高度饱和呈流态化推动坡脚土体快速下滑.基于室内模型试验，初步分析了缩尺试验条件下降雨诱发泥石流形成形态机理，为降雨诱发泥石流的进一步研究提供参考.An experiment of debris flow was carried out to study the influence of grain size distribution on starting progress mode by using the self-developed small-scale model flume under the condition of artificial rainfall.By using coarse sand （1~2 mm）and fine sand （0.075~0.25 mm）,the model was made according to the quality ratio.Model test study finds that,with fine content increasing from 20%to 100%,failure pattern changes from layered and clumpy slide to fluidized flow.By using GeoDog software to analyze displacement and a pore pressure gauge to measure pore pressure changes,we have found sliding plane developing in layered and clumpy slide,and pore pressure decreasing with crack generation,and increasing with water seeping into crack.There is no crack development in fluidized flow, and pore pressure momentarily drops to a small value when damage occurs.The average volume of the starting for flu-idized flow is bigger than that for layered and clumpy slide.The formation mechanism for layered and clumpy slide is that water penetrates quickly,causing slope foot damage,and the slope collapses for losing support.For fluidized flow,the permeability coefficient is small,the soil of the back is highly saturated,and liquid causes the slope to de-cline rapidly.Based on the indoor model test of rainfall-induced debris flow,the formation mechanisms of debris flow modes were summarized.

关 键 词：泥石流 颗粒组分 降雨 

分 类 号：P64[天文地球—地质矿产勘探]