Rock Slope Stability Analysis With Carbonaceous Mudstone Interlayer Weak

Stability of rock slope with carbonaceous mudstone weak interlayer is one of the hot topics of current research.carbonaceous mudstone weak interlayer is one of the hot topics of current research.On the one hand strength of carbonaceous mudstone is greatly reduced due to soften with water;on the other hand creep properties of weak intercalation is very significant,instability phenomena of this type of slope happens very often both the two hands,and especially in highway construction,this show that stability problems of slope of carbonaceous mudstone with weak interlayer have become a major bottleneck in highway construction.To this end,relying on the highway of Yizhou to Liuzhai in Guangxi Province,mechanism of softening of carbonaceous mudstone,water to carbonaceous mudstone strength weakening effect,carbonaceous mudstone creep characteristics and sensitivity factor of slope stability are researched in this paper,stability of slope with carbonaceous mudstone weak interlayer is researched by laboratory experiments,numerical simulation and theoretical analysis,results in this paper are achieved as follow:1)X-ray diffraction experiments show that the highest content of carbonaceous mudstone mineral composition is quartz,kaolinite and montmorillonite are mainly clay minerals,the content of illite is very low;shear strength of carbonaceous mudstone is reduced with increase of water content,roughly exponentially,Flooding will cause it to soften and cause the shear strength decrease again.2)Carbonaceous mudstone interlayer weak rock slope stability is studied by numerical simulation with FLAC3 D,Weak interlayer sensitivity factors are analyzed by orthogonal method,the results show: factor of the degree of influence descending order is inclination of interlayer,internal friction angle of interlayer,cohesion of interlayer,thickness of interlayer;slope stability is worst when inclination of interlayer is 45°.3)The effects of moisture of carbonaceous mudstone shear surface on slope stability is researched,research shows: With the increase of water content of carbonaceous mudstone surface of shear,the slope stability decreases,slope is instability when the water content of carbonaceous mudstone shear plane reach 17%.4)Constitutive model is established based on the carbonaceous mudstone compression creep,slope stability of carbonaceous mudstone interlayer weak is studied base on method of strength reduction by numerical simulation with FLAC3 D,then comparison with elastoplastic model,research shows:the final amount of displacement of monitoring points of carbonaceous mudstone weak interlayer which consider rheological properties is about 2 to 2.5 times the amount of displacement of only considerring elastic-plastic properties;slope safety factor is 1.48 when its elastic-plastic only be considered,the safety factor of slope is 1.26 when basing on the compressive creep properties of carbonaceous mudstone,the safety factor of slope reduced by 15% compared to elastoplastic model,impact of weak creep properties of carbonaceous mudstone interlayer to slope stability is fully validated.