Mechanical Characteristics Research Of High Fill Slab Culverts In Southern Mountainous Area

With the extension of the highway to the mountainous area,the number of high fillslab culverts built in mountainous regions has gradually increased.On the one hand,the gullies in the mountain areas are well-developed and complex.Soft soils and high liquid limit soils are widely distributed,and the bearing capacity of the foundations is low,so putting forward high requirements for the construction of high fill slab culverts in the mountains.On the other hand,due to the lack of systematic understanding by some designers on the mechanical characteristics of high fill slab culverts,the calculation method of top soil pressure of culverts only considers H/D in current norms.and there is a large error between the calculated results and the actual stress,so the disease of culverts are common in the operating process.In fact,the fill-culvert-foundation is the unity of coordinated deformation.The mechanical characteristics of high fill slab culverts are closely related to the factors such as filling,foundation conditions,gully topography,and structure type and dimensions.Therefore,the stress characteristics of high fill slab culverts are worth studying under complex mountain conditions.This article relies on the practical projects of high fill slab culverts in the Bao Mao highway(Guangdong section),combined with the characteristics of southern mountainous areas,using geotechnical centrifugal model tests,numerical simulations,and other methods.Studying the mechanical properties of high fill slab culverts under the influence of factors such as filling height and modulus,foundation modulus,gully topography,structural size,etc.The main results obtained are as follows.(1)Under the influence of different filling height and modulus,foundation modulus,gully width and slope,and structure size,the middle of the lower margin of the cover plate and the middle superior margin of the base are all subjected to large tensile stress.These are the weak parts of the culvert,and the middle of the lower margin of the cover is the most unfavorable position of the structure.(2)The vertical earth pressure at the top of the culvert,the base reaction,and the K_s increase with the increase of the foundation soil modulus,the gully width,and the filling height.(3)Reducing the filling modulus on the top of the culvert or increasing the gully slope can obviously reduce the vertical earth pressure on the top,the base reaction and the K_s,and the effect is more obvious than the modulus of the foundation,the gully width and the size of the structure.It is suggested to reduce the earth pressure on the top of the culvert by changing the gully slope and the bury way of the culvert top.(4)Combined with the research results,the calculation formula of the vertical earth pressure coefficient Ks on the culvert top applied to the high fill slab culvert in the southern mountain area is proposed,as well as the design and construction technology suggestions.Based on the research results of the mechanical characteristics of high fill slab culverts in southern mountainous areas,this paper can provide reasonable suggestions for the design and construction of high fill slab culverts to ensure the safe and reliable operation of culverts in late stage operation.It has important reference significance and application value.