| As an important part of highway engineering,culvert has always been an important subject studied by scholars at home and abroad.The earth pressure calculation theory of culvert is also the core content of many scholars in the culvert field.In order to obtain the calculation method of the earth pressure on the culvert top and the optimal load reduction scheme,two indoor model tests are carried out in this paper,which are respectively the load reduction model test of culvert with EPS and the settlement model test of similar soil culvert with aluminium bar.The load reduction model test of culvert with EPS is the model test of rigid culvert and flexible culvert filled with sand filling.The influence of thickness and layers of EPS laid on culvert top on earth pressure and displacement of fill is studied,and the distribution and variation law of earth pressure and displacement around culvert under different filling heights are clarified.The settlement model test of similar soil culvert with aluminium bar is a model test of artificial settlement of three kinds of mixed aluminium bar with different particle sizes.The soil arch evolution law of filling under different relative settlement Δs and different filling height H is studied.The shape and height of soil arching effect in filling soil and the variation law of culvert top equal settlement surface height are obtained,and the calculation method of vertical earth pressure on culvert top considering soil arching effect is put forward.Through model test and theoretical analysis,the main conclusions are as follows:(1)When the thickness of EPS laid on the top of culvert is the same,the load reduction effect of two-layer EPS is better than that of single-layer EPS.Under the condition that each layer has the same thickness of EPS,the load reduction efficiency of two layers of EPS is also higher than that of single layer and multi layers.Compared with the rigid circular culvert,the load reduction effect of flexible circular culvert is more significant.And the test results can provide reference for the protection of culvert structure and uneven settlement of embankment in practical engineering.(2)The soil arch on the top of culvert varies with the relative settlement of the central and lateral soil prism and the height of the filling.In this process,three elliptical soil archs with different shapes will be formed in the top of culvert and the filling soil on both sides.Because of the relative displacement of the central and lateral soil prism,sliding failure occurs.Two inclined shear planes will be formed on both sides of the culvert top soil arch,and an equal subsidence surface will be formed above the culvert top soil arch.Two inclined shear planes and one equal subsidence surface form a trapezoidal soil arch area.With the change of the shape of soil arch,the inclination angle of shear plane and the height of equal settlement surface also change.(3)According to the data obtained from the load reduction model test of culvert with EPS,the formula for calculating the non-linear earth pressure is fitted by regression analysis,and compared with the current formula for calculating the earth pressure of culverts,it is concluded that the value of the earth pressure calculated by the non-linear earth pressure calculation method is closer to the actual engineering.According to the results of settlement model test of similar soil culvert with aluminium bar,and the stage analysis of soil arching effect on culvert top is carried out,the calculation method of soil pressure on culvert top at different stages is studied.The research results can provide reference for the calculation of earth pressure on culvert top. |
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