缓慢复活型滑坡滑带土的蠕变性质与特征强度试验研究_蒋秀姿

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1、第36卷第2期岩土力学Vol.36No.22015年2月RockandSoilMechanicsFeb.2015DOI：10.16285/j.rsm.2015.02.027缓慢复活型滑坡滑带土的蠕变性质与特征强度试验研究蒋秀姿，文宝萍（中国地质大学（北京）水资源与环境学院，北京100083）摘要：锁儿头滑坡是甘肃省舟曲县城附近、体积约72.85×106m3的一个巨型老滑坡。20世纪70年代末滑坡开始复活，至今一直处于缓慢活动之中，显示滑坡活动具有典型的蠕动特点。滑带力学特性是控制滑坡活动机制的关键因素之一，为了弄清该滑坡滑带物质的蠕变性质以及控制滑坡活动

2、的强度指标，通过滑带土残余状态下的直剪蠕变试验，研究了滑坡滑带土的蠕变特性，比较了滑带长期强度和残余强度的关系。研究发现，滑带土蠕变特性与应力状态相关，滑带进入加速蠕变的临界剪应力和剪切速率均与正应力线性正相关。该滑坡应力状态指示其已具备进入加速蠕变的条件。残余状态下该滑坡滑带土的长期与残余强度基本等价，前者略大于后者，且增大量值与正应力有负相关关系。关键词：滑带土；残余蠕变试验；长期强度；残余强度中图分类号：TU457文献标识码：A文章编号：1000－7598(2015)02－0495－08Creepbehaviorofslipzoneofreacti

3、vatedslow-movinglandslideanditscharacteristicstrengthJIANGXiu-zi,WENBao-ping(SchoolofWaterResourcesandEnvironment,ChinaUniversityofGeosciences(Beijing),Beijing100083,China)Abstract:TheSuoertoulandslide,agiantoldlandslidewithavolumeof72.85×106m3inZhouqucounty,GansuprovinceofChina,

4、hasbeenreactivatedwithasmallratesince1970’s.Theslow-movingcharacterindicatesthetypicalrheologicalbehaviorofthelandslide.Itiswellknownthatmechanicalcharacteristicofslipzoneplaysanimportantroleinlandslideactivities.Inordertoclarifythecreepbehaviorofslipzoneandtherelationshipbetween

5、long-termstrengthandresidualstrength,aseriesofdirectedcreepsheartestsunderresidualstateisemployed.Itisfoundthatthecreepbehaviorofresidualslipzoneisstronglydependentonnormalandshearstress,withtwocriticalshearstressesandtwocriticalinitialstrainrates.Moreover,itcanbefoundthatthecrit

6、icalshearstressandstrainrate,whenthecreepdevelopsintoacceleratedstage,havealinearrelationshipwithnormalstressseparately.Basedonthelinearrelationshipbetweencriticalshearstressandnormalstress,itcanbespeculatedthattheshearstressconditionoftheSuoertoulandslidehasbeeninacceleratedcree

7、pstatealready.Meanwhile,therelationshipbetweenlong-termstrengthandresidualstrengthisanalyzedandcompared.Itisfoundthatlong-termstrengthofthelandslide’sslipzoneisslightlygreaterthanitsresidualstrength,andthemagnitudeoftheirdifferenceisnegativelycorrelatedwithnormalstress.Keywords:s

8、oilatslipsurface;residualcreeptest;longt