Study On Shear Strength Characteristics Of Soft Interlayers In Metamorphic Rocks Of Daba Mountain,qinling Mountains

The soft intercalation in rock slope is an important factor affecting the stability of rock slope,so the soft intercalation has always been a key problem in slope engineering.This paper first summarizes the research status quo of weak intercalations,found that most of the academic literature is all about weak interlayer on the study of slope stability and failure mechanism of slope,the study of metamorphic rock in weak layers is relatively small,so this article is based on typical regional highway slope in qinling dabashan mountain metamorphic rocks of the soft interlayer related research.The specific research results are as follows:This paper first introduces the engineering geological conditions of Zhushan metamorphic rock area in Qinba Mountainous area from the aspects of natural conditions,topography and landform,stratigraphic lithology and so on.Of metamorphic rock mass structure surface are classified in this paper,the genetic type and characteristics,pointed out the structural plane in metamorphic rock according to the different geological formation can be divided into primary structure planes,secondary structure and tectonic structural planes,weak interlayer is nature in weak rock mass and has a certain thickness of the weak structural plane,and the weak interlayer shear strength is a key factor to control the stability of slope.Sample configuration will be weak intercalated into the reshaping of the moisture content of different samples,and then using indoor medium-sized direct shear test in 100 kpa,200 kpa,300 kpa,400 kpa under the normal stress of shearing,test results,the stress-displacement curve,the curves of shear strength parameters,resulting in weak interlayer shear strength indexes under different moisture content.The particle flow software PFC2 D was used to simulate the direct shear test.First expounds on the basic theory of particle flow method,and then according to the macro test particles flow numerical model is established,using the control variable method respectively analysis select eight kinds of mesoscopic parameters influence on stress-displacement curve,then through the test algorithm for mesoscopic parameters calibration,finally will calibrate good mesoscopic parameters fitting with corresponding moisture content of weak intercalations,found that there is a certain rule.Through eight kinds of mesoscopic parameters and the fitting relationship between the moisture content,predict the moisture content was 28.34% of mesoscopic numerical model parameter values,resulting in weak layers under the moisture content of numerical simulation,the stress-displacement curve before the moisture content of indoor direct shear test,macro,stress-displacement curve obtained by mesoscopic condition analysis,found that the alignment is higher,shows that prediction of mesoscopic parameter values can be used to conduct numerical analysis,thus to some extent,get a kind of macro-the relationship between the mesoscopic parameters,it has very important significance and research value.Based on FLAC3 D of sampling in slope stability analysis,combining with the above only consider the weak intercalations under different moisture content influence on slope stability,will get the corresponding test and predict the moisture content of soft interlayer shear strength index in numerical calculation,get the slope of the horizontal displacement nephogram and shear strain increment contours as well as the safety factor,it can be seen that with the increase of moisture content of weak intercalations,gradually reduce the slope stability.