Study On The Lateral Earth Pressure Of Positive-Buried Culvert

With the rapid development of national economy, infrastructure and the key projects, such as the Middle Route in the South-to-North Water Transfer Project and Shanxi large-scale water conservancy network which require crossing mountains are increasing vigorously. This makes culvert of underground structures which has a low cost relatively appear more and more in construction projects. However, the buried position of culvert is concealed, it’s difficult to detect and overhaul timely which will result in disastrous accidents. Therefore, the importance of design and construction of these projects is self-evident. At present, the culvert theory of earth pressure is still not mature, the formulas are numerous and there is no unified theory, and even the algorithm, standards and scope of application in various specifications are different. Hence it causes the results have great difference, either conservative which results in waste of resources or unsafe which causes hidden trouble. Therefore, further study of earth pressure theory of culvert has a strong practical significance.Based on the experiment described in the literature [47][48], ANSYS was used to simulate and analyze the vertical soil pressure distribution of ditch culvert in rigid foundation under the influence of the trench width and slope factors in this paper. Also, the vertical earth pressure coefficient changes were obtained, the results are in good agreement with the results of model experiment. On this basis, the influence on lateral earth pressure of different nature of filling in the rigid foundation and the different ratio of foundation elastic modulus in the flexible foundation were explored further and the variation of lateral earth pressure coefficient was obtained by the establishment of numerical model. The relationship between plane of equal settlement and lateral earth pressure of positive-buried culvert and change regularity of distribution shape of lateral earth pressure were also obtained. The results show that:under the condition of rigid foundation, with the increase of filling height, the distribution shape of lateral earth pressure changes from trapezoid to the inverted trapezoid gradually, When H/D is constant, the greater the Eo, the lower the plane of equal settlement, the greater the lateral earth pressure; When Eo is constant, the greater H/D, the lower the plane of equal settlement, the greater the lateral earth pressure; Lateral earth pressure coefficient increases firstly and then tends to a fixed value with the increase of filling height; The impact of Eo which is more than30MPa on lateral earth pressure and coefficient of lateral earth pressure is less. Under the conditions of the flexible foundation, when the ratio of foundation elastic modulus is less than50, the distribution shape of lateral earth pressure is trapezoidal; When the ratio of foundation elastic modulus is more than50, the distribution shape of lateral earth pressure becomes rectangular gradually; When the ratio of foundation elastic modulus is more than100, the distribution shape changes little; When H/D is constant, the greater the ratio of foundation elastic modulus, the higher the plane of equal settlement, the smaller the lateral earth pressure; When the ratio of foundation elastic modulus is constant, the smaller the H/D, the higher the plane of equal settlement, the smaller the lateral earth pressure. Lateral earth pressure coefficient decrease firstly and then tends to a fixed value with the increases of filling height under the flexibility foundation, which is different with rigid foundation.In this paper, the finite element method is mainly used to simulate and analyze the impact of the backfill nature and the ratio of foundation elastic modulus on the lateral earth pressure of Culverts, which has great significance for improving the Computation Theory of culvert further, some conclusions and recommendations that can guide design and construction are obtained also, but this still requires test of actual project.