The Drying-wetting Cycle Effect On Properties Of Soft Rock Filling For Subgrade

Soft rock is a kind of natural material which can easily soften in water, anddisintegration and sludging will happen to it easily especially under load coupling function.With the growing importance of national road infrastructure construction and environmentprotection, problems come that so much soft rock distributing in some areas cannot be useddirectly, but also cannot be abandoned casually. Thus, based on sericite schist andmudstone, the article studies the performance evolution of soft rock embankment fillerunder the cycle effect of atmosphere. Also, the degradation mechanism of soft rockembankment filler performance is revealed. And Midas-GTS is used to simulate thedeformation response discipline of mudstone embankment under vehicle loading, and thenthe reasonable range of soft rock embankment filler is determined. Main results are asfollows:(1) When the biggest particle size ranges from10to20mm, the CBR of sericite schistwill be greater. The effect of dry-wet cycle on CBR of sericite schist will be less if thebiggest particle size is less than10mm. When sericite schist of particle size of10mm ischosen to fill the embankment, not only the strength of embankment can be ensured, butalso the effect of particle disintegration on its structure stability can be reduced. Thus, thereasonable greatest filling particle size is10mm.(2) The essential effect of dry-wet cycle function is to destroy the particle structure.Compared to original condition, it enhances cohesion of mudstone disintegration at anincrease of95.8%, but it reduces the internal friction angle at a decrease of26.5%. But as awhole, it weakens the strength of mudstone.(3) Although restricted by the overlying load, alternate dry and wet function still canlead to the repeated expansion and contraction behavior of the soil.Thus, the compressibility of mudstone is enhanced almost at an increase of35.5%.Mesoscopic porosity analysis shows that the sizes of pore compressed mainly distributebelow1μm。(4) When the initial density of mudstone specimens is smaller, overlying load andwet-dry cycle function mainly cause the soil compressing. With the times of dry and wetcycle growing, mudstone specimens will be tighter and tighter.The compression deformation mainly happens in the stage of dry-wet cycle.Comparedto the origin, compression coefficient decreases about40.1%and the mesoscopic porosity analysis shows that the sizes of pore compressed mainly distribute above1μm.(5) According to the calculation conditions, the influence of thickness of outsourcingsoil on subgrade settlement deformation is very small, but it plays a significant role inlimiting the horizontal displacement of subgrade. The thickness of outsourcing soil shouldbe controlled at2m. If the Filling range of mudstone is limited below the pavement morethan3m, the replacement layer can be in the core area which lane load has an effect on,and the settlement deformation of mudstone subgrade can also be delayed efficiently.