Stability Evaluation Of Dujiang Landslide In Sandu County,Guizhou Province

The thesis studies the stability evaluation of dujiang slope in Shui nationality in Sandu county,Guizhou Province.The thesis analyzes the stability of the slope under the current condition data collection and collation and studies the hydrogeologial condition and engineering geology condition and environmental geology condition and engineering exploration drilling and buried deep displacement monitoring equipment and data gathering.The thesis also uses the monitoring results of deep displacement and the transfer coefficient method,to analyze the stability of the slope under the current condition uses.The two analyses were compared and draw the following conclusions:1?The underlying area in the study area is the modified tuff and silty SLATE of qingbaikouxiajang group qingshuijiang formation?Pt31dq?,with no weathering.The middle part is the granular structure of strong weathering layer and medium weathering layer with developed joints and fissures.The middle weathering layer is stratiform structure,block structure,relatively developed joints and fractures,broken rock mass,and the core is mostly block.The soft rocks in this layer are easily softened when exposed to water.The top is the mixed fill of quaternary?Q?macadam soil and the strong weathering layer of variable tuff and silty sslte.This rock formation has loose structure,large porosity,strong water permeability,low strength,strong compressibility,expansibility and plasticity,and is prone to landslides,debris flows and other geological disasters.The average pore ratio of soil layer was 0.88,specific gravity 2.68,severe 18.0 KN/m³,cohesion 22.3 kPa,and internal friction Angle 6.8°.2?The slide surface of dujiang landslide is generally continuous and stable with slight fluctuation.The slide bed is a middle weathering bed of qingshuijiang formation(Pt₃^1dq)in xiajang group of qingshuijiang formation.The slide bed is thin to medium thickness.It has a layered structure and massive structure.The joints and fractures are developed,the rock mass is broken,and the core is mostly blocky.The rock is easy to weathering,water after softening disintegration.The sliders are mainly artificial fill gravel soil and subterraneously weathered tuff and silty slate.The thickness of the slide is between 15.8m and 25.0m.Under the condition of long-term soaking such as rainstorm,it is easy to soften and form unstable landslide.3?The main causes of slope failure in the study area are as follows:Unreasonable piling and drainage of historical human engineering activities and change the original landslide stress state.During the construction of the resettlement project,the foot of the slope is excavated to form a face with a large slope,which changes the original stress field.The shear strength of the slide body is very low and the porosity is large.4?The data analysis of deep displacement monitoring and the method of transfer coefficient show the stability analysis of landslide systematically.The monitoring point sj1-1 has deformation and instability in the monitoring process,and the retaining wall project is adopted.After the support,there is still a 26.0mm cumulative displacement deformation,which indicates that the support project did not make the slope of this section stable,and this section is still in a deformation state.The maximum cumulative displacement and deformation of sj2-1 monitoring point is117.7mm,and the cumulative displacement and deformation of 14.0m and 8.0m buried deep at this point is 4.8mm and 6.8mm.At present,no deformation signs have been found on the surface of this point,and it is in a creep state.The maximum cumulative displacement and deformation of the other five monitoring points ranged from 1.1mm to 31.0mm,and no deformation signs have been found on the surface.According to the transfer coefficient method,the stability coefficient of 1-1natural condition is 1.0067,and the slide body is in an understable state.The stability coefficient was 0.9742 under the condition of+50 years of heavy rain?condition 2?,which was lower than the safety coefficient of 1.15 under the design condition.The1-1 section was in an unstable state as a whole.