Silty Clay Tunnel Deformation Characteristics Due to Water Content Variation
To study the influence of water content variation on the deformation characteristics of silty clay tunnel,the Dayingpo tunnel on Yangliu-Xuanwei expressway was taken as the study object.First,on the basis of investigating site disaster,the soil samples were taken from the construction site.The unconsolidated undrained triaxial compression tests were carried out on the remolded soil samples according to the different water contents.The physical and mechanical parameters of soil samples were obtained.Second,the numerical simulation method was used to analyze the deformation characteristics of silty-clay-stratum highway tunnel surrounding rock with different water contents and tunnel burry depths.Finally,the deformation characteristics were revealed according to the field monitoring data,and were verified with the numerical simulation result.The result indicates that the water content has the significant effect on the failure type and final failure mode of soil.When the water content is less than 30%,the failure mode of silty clay in the area is shear failure,showing strain softening characteristics.When the water content reaches 35%,the silty clay does not produce shear failure,and the soil sample deforms in drum-shaped,showing rheological properties.The surrounding rock deformation increases with the increase of burry depth.When the water content is less than 25%,it increases linearly.When the water content reaches 30%,it increases exponentially.At the same burry depth,the surrounding rock deformation increases with the increase of water content,and increases sharply when the water content is over 25%.The surrounding rock deformation has the characteristics of large deformation,fast deformation speed,mainly vertical deformation,and significant influence by construction disturbance.The deformation mainly occurs after the excavation of support to upper bench,when the surrounding rock deformation speed is the fastest.When the initial support is closed into a ring,the surrounding rock deformation basically converges.
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