Research On Soil Pressure Of Culvert Area In High Embankment Based On Laboratory Model Test

Passage of high fill embankments in mountainous areas will inevitably hinder the normal development of existing waterways and traffic routes.In the event of adverse geology,waterways and traffic routes,culverts are usually adopted.The overlying load on the culvert of high fill embankment is relatively large.The lack of research on the factors affecting the soil pressure and stress in the culvert area will cause some culverts to be damaged to varying degrees in the later use of high-grade freeways,which will greatly increase the cost of restoration.However,the model test has the characteristics of high efficiency,strong intuitiveness,and can also study different working conditions under the condition of controlling single factor,and thus is widely used in laboratory research.This paper is based on the laboratory model test to study the soil pressure of the high fill embankment culvert area.This paper takes the high fill embankment culvert of Puyan freeway as the research object.Based on the results of field survey,sampling test and on-site monitoring,the laboratory model test of high fill embankment culvert is built using the similarity principle.Combined with on-site monitoring and theoretical calculation methods,the paper studies the distribution law of soil pressure in the culvert area of high fill embankment and analyses the boundary conditions and impact factors of the soil arch effect.Firstly,the field pressure and deformation characteristics of the culvert area were measured on the site of the high fill embankment culvert area of the Puyan freeway,and also the distribution of soil pressure around the culvert under the 16 m high embankment was obtained.The paper analyzed the stress characteristics of culverts and the factors affecting soil pressure.It is found that the soil pressure increases nonlinearly with the filling height after the fill in the study area reaches a certain height.The soil arching effect occurs above the culvert and the top earth pressure is smaller than the theoretical value.However the arch structure itself is a shear band,stress concentration obviously exists on both sides of culverts.From this analysis,the critical conditions of the soil arching effect are generated.Then based on the prototype of the culvert and embankment in the site,a laboratory model test of earth pressure in the culvert area was conducted using similar principles.Under the conditions of different heights of 12,16,18,20,and 24 m static load and 90% compaction,the soil pressure changes were monitored.Changing soil compaction on both sides of the culvert to 93% and continuing the test,the impact of changes in compaction on the soil pressure on both sides of the culvert was analyzed.The results indicate that a linear increasing trend is between the culvert earth pressure and filling height at first,and when the filling height reaches to a certain value,which shows a non-linear increase.The earth pressure of on the culvert top presents a parabolic distribution with increasing distance from the center of the culvert,and the lateral soil pressure also has a non-uniform distribution law.The pressure distribution on the side center is the smallest and the stress concentration phenomenon exists on the top corner of the culvert.For the culverts with the same filling height,increasing the soil compaction on both sides of the culvert can significantly reduce the concentration of soil pressure at the top of the culvert,which providing support for the reduction mechanism of the culvert area.Finally,under the consideration of stress concentration and soil arching effects,the theory of earth pressure calculation was deduced and optimized.The calculation model was validated using the laboratory test and field monitoring data,and the applicable conditions were analyzed.Putting forward the calculation theory of soil pressure at the top of the culvert and also the lateral.What's more,the boundary and the applicable conditions of the analytical expression are optimizated and supplemented.Through the above studies,the paper obtained the distribution and variation of soil pressure on the culverts of high fill embankments,and the various factors affecting the culvert stress were clearly defined.Combined with the actual condition,using of reasonable load shedding measures for the culverts,so that it was possible to avoid the occurrence of culvert diseases and improve the freeway' service life.On the other hand,it greatly reduces the construction cost of high fill culverts and avoids the waste of resources and difficulty of construction due to conservative designs,which has an important theoretical and engineering practical significance.