Study On The Impact Of Seepage On Compacted Loess Road Embankment

Loess is widely distributed in the northwestern part of China and has a deep cover.It can be used as both an embankment and a road construction material.The fill embankment is one of the main forms of highway construction in the loess area.However,the engineering properties of loess-filled embankments are special.Highway embankments are likely to cause ground subsidence,slope slippage,and road surface grouting under the influence of frequent water infiltration.The infiltration caused by rainfall infiltration and agricultural irrigation is undoubtedly the main form of water infiltration.In this paper,compacted loess is taken as the research object,and the seepage characteristics of compacted loess with different compaction coefficients and different saturations are studied through laboratory tests.On this basis,based on the theory of saturated-unsaturated seepage,a simplified model of the research problem is established,and the finite element analysis software is used to establish the model.The pore water pressure and effective stress in the compacted loess embankment are analyzed under rainfall and irrigation conditions.And the effect of displacement under self-weight conditions,combined with the research results,proposes preventive measures for weakening the embankment.The main research contents and understanding of the thesis are as follows:1.Through the basic physical property index test and seepage test on a loess in Lanzhou,the corresponding parameters are provided for subsequent numerical simulation.The experimental study obtained the compaction coefficient and the compacted loess under different saturations to obtain the relevant seepage law.It is found that when the compaction coefficient of compacted loess is higher than 0.85,there is an initial hydraulic gradient in the seepage in saturated compacted loess;when the saturation is low,the seepage does not occur when the loess is in the "water closed" state,mainly The water diffusion is dominant,and the seepage in the unsaturated compacted loess occurs only when the saturation is high and reaches the "double open" state.2.Apply the SEEP/W and SIGMA/W finite element software modules to establish the embankment model under rainfall conditions,and compare and analyze the different rainfall intensity,different embankment height,different embankment compaction coefficient and different embankment saturation conditions.Changes in displacement under water pressure,effective stress and self-weight conditions.According to the analysis and calculation,during the process of rainfall infiltration,the surface soil of the embankment is obviously affected by rainfall,and it has the greatest influence on the foot of the slope,and then gradually spreads into the interior of the embankment.Through the establishment of models,it provides a certain reference for the subsequent embankment optimization design and disaster prevention.3.Establish an analytical model for the impact of embankments on agricultural irrigation.Comparing the different sprinkler irrigation intensity,different irrigation types and the different distances of the sprinkler irrigation area from the embankment slope,the dynamic changes of pore water pressure,effective stress and vertical displacement of the embankment slope,combined with the research results,put forward effective preventive measures.After the analysis,it is concluded that the irrigation mainly affects the foot of the embankment on the water surface,and the influence on the vertical direction of the embankment slope is large.The effect of the pre-buried concrete block at the edge of the irrigated area is 1.5m.