Study On Earth Pressure Distribution And Deformation Characteristics Of High Fill Cover Culvert

With the development of China's high-grade highways in the mountainous area,the high-filled roadbed of the high-grade highways in the mountainous areas and the corresponding high-filled cover culverts are more.High-loading,culvert and foundation are the unified body of coordinated deformation.Under the mountainous terrain,the mechanism of filling-culvert-foundation is complex and variable,and the culvert often produces different degrees of stress concentration,resulting in“Ten culvert and nine cracks”.On the one hand,the existing calculation theory of earth pressure in high-fill culverts neglects that the filling,culvert and foundation are the whole of the system coordination work,and the formation mechanism of the earth pressure distribution characteristics of the high-fill culvert is not detected.On the other hand,the existing soil pressure calculation model and method for high-fill culverts do not consider the distribution characteristics of culvert earth pressure,and generally consider it as a uniform load,resulting in a large error in the calculation results and the inevitable culvert actual force.Therefore,the study on the pressure distribution and deformation characteristics of culvert with high fill cover is carried out.Based on the K13+198.5 high fill cover culvert entity project of Baomao Expressway(Guangdong District),the pressure distribution and deformation characteristics of the high fill cover culvert were studied by field test.The effects of different fill properties,foundation soil properties and gully topography on the humey pressure and fill deformation of the cover were analyzed by numerical simulation software.The calculation model of high fill cover culvert considering the distribution characteristics of culvert earth pressure is established,and the calculation formula of culvert pressure of high fill cover is derived.The main research results are as follows:(1)The vertical earth pressure between the culvert and the base is“saddle-shaped”and“reverse saddle-shaped”along the span of the culvert.The horizontal earth pressure is“3-shaped”along the vertical direction of the side wall,and the earth pressure of the culvert shows unevenness.The vertical earth pressure between the culvert and the base is greater than the calculated value of the current standard soil column method,and the horizontal earth pressure of the side wall is less than the static earth pressure.(2)The difference between the culvert and the filling stiffness and the topography of the culvert caused by the factors such as the difference between the culvert and the filling of the culvert is the intrinsic cause of the concentration,uneven distribution and eccentric load of the culvert.(3)The vertical vertical earth pressure of the culvert is positively correlated with the internal friction angle of the fill,the Poisson's ratio of the fill,the modulus of the soil,the internal friction angle of the foundation,and the Poisson's ratio of the soil.It is negatively correlated with the fill modulus.The vertical ground pressure of the basement is positively correlated with the internal friction angle of the fill,the soil modulus of the foundation,the friction angle of the foundation soil,and the Poisson's ratio of the soil.It is negatively correlated with the fill modulus.The horizontal soil pressure of the side wall is positively correlated with the filling modulus,internal friction angle and Poisson's ratio,and negatively correlated with the soil modulus.The cohesive force of the fill and foundation soil has no obvious influence on the earth pressure of the culvert,and may not be considered in the theoretical calculation.(4)The vertical earth pressure between the culvert and the base is positively correlated with the width of the valley,and negatively correlated with the slope of the valley.The horizontal soil pressure of the side wall shows the opposite trend.After the width of the valley reaches 5D,the earth pressure of the culvert changes little,and it can be approximated that the force state of the culvert is the same as that of the culvert without the valley.When the slope of the valley is 90°,the culvert has the best load shedding effect.(5)The calculation model of the culvert pressure of the high fill cover plate takes into account the distribution characteristics of the vertical earth pressure of the culvert“large in the middle and small on both sides”,which better reflects the actual stress state of the culvert.The vertical soil pressure and K_s variation calculated by the formula in this paper are in good agreement with the field test results,and the error is less than 20%.