Study On Strength Characteristics Of Weak Interlayer Soil And Its Influence On Slope Stability In Typical Area Of Clastic Rock In Guangxi

It is very important to study the strength variation of weak interlayer soil under different factors,which can be used to analyze and judge the stability of clastic rock slope with weak interlayer and slope protection in Guangxi.Supported by the Guangxi Zhuang Autonomous Region Land and Resources Department of major scientific research project "The study of geological disasters online early-warning technology of clastic rock area in Guangxi",the weak interlayer soil in the typical clastic rock slope was set as the research object to study its physical properties,shear strength and the corresponding strength parameters change with three factors variation(water content,fines content,dry-wet cycle times)and consolidated shear creep characteristics.On the basis of experimental results,numerical simulation of clastic rock slope stability with weak interlayer was conducted to reflect the influence of weak interlayer soil strength changes on slope stability.The main research contents and results of this paper are as follows:1.Study on the engineering geological conditions of the clastic rocks in Guangxi.The clastic rocks distribution,landslide development characteristics in clastic rock region and weak inter layer types in Guangxi were studied firstly,then Xilin County of Baise City was selected as the typical study area based on the above results.For Xilin County,we explored the geological foundation of the weak interlayer,illustrated the potential effect of weak interlayer on slope stability,and analyzed the strength change regulation of weak interlayer by theoretical analysis,which could provide theoretical guidance for the following experiments.2.Experimental study on the physical and mechanical properties of weak interlayer soil in clastic rock slope in Xilin County,Guangxi.The basic physical properties tests and X-ray diffraction test were used to study the parameters of weak interlayer.Results show that the weak interlayer soil has the characteristics of high clay content,poor water resistance and easy to be softened by water.The indoor direct shear tests show that the strength of weak interlayer soil are all reduced in different degree by the change of the water content,fines content and dry-wet cycle times.The influence of water content on weak interlayer soil's strength is the most of all.3.Experimental study on the long-term strength of weak interlayer soil in clastic rock slope in Xilin County,Guangxi.The shear creep test of weak interlayer was conducted by using ZLB-1 type triple rheometer,the whole process creep curves,respectively loading creep curves and stress-strain isochronous curves of weak interlayer soil were obtained,and its long-term strength was also determined.The results show that the creep characteristics of weak interlayer soil is obvious in clastic rock area in Xilin,and the creep curves develop in a nonlinear way.With the increase of shear stress,the creep rate in creep steady is higher,the displacement is larger,and the time up to creep steady increases.Under natural condition,the long-term strength of weak interlayer soil has a great damage compared with peak strength under different vertical pressures.It shows that the long-term load would seriously reduce the shear strength of weak interlayer soil,the deterioration rates are about 52.12%?55.29%,and we should pay full attention to the strength loss problem caused by the creep characteristics of weak interlayer soil in practical engineering.4.Numerical simulation on clastic rock slope stability of weak interlayer soil with different strength in Xilin County,Guangxi.The stability of clastic rock slope with weak interlayer under different weak interlayer soil strength condition was calculated by using Geo-Studio software.Results show that the strength loss of weak interlayer soil caused by the change of water content,fines content,dry-wet cycle times and creep characteristics,will directly lead to the decrease of slope stability,or slope failure under certain conditions.With the increase of water content,the slope stability decreases with the inverse S pattern,and it decreases exponentially with the increase of fines content and dry-wet cycle times.What's more,the creep characteristics of weak interlayer soil will seriously undermine slope stability,and often make slope sudden fail.