| The soil moisture field in the reclamation area will change significantly at the same time and after a long time,which will bring about the change of the physical and mechanical properties of the soft soil in the reclamation area,and its direct influence is the engineering geological hazards,such as surface subsidence,cracking and sliding,which harm the safety of the surface construction.In road works,such as pavement cracks often occur along the water level of the road surface.In this paper,combined with the practice of Highway Engineering in coastal areas,the influence of soil moisture field change on the stress and deformation of subgrade is systematically carried out by the combination of theoretical research,indoor test and numerical simulation.The main contents of this study include the following aspects.First,based on the discussion of the theory of deformation of marine soft soil,the shrinkage mechanism,shrinkage process and shrinkage factors of soft soil are analyzed.The indoor shrinkage experiment was carried out on the soft soil samples in the coastal reclamation area of Taizhou,Zhejiang,and the time correlation of the soft soil evaporation shrinkage was discussed.The difference between the horizontal and vertical shrinkage deformation of the soft soil was compared,and the proposed value of the shrinkage characteristic curve and the shrinkage coefficient for different initial water content was given.The experimental results show that the linear shrinkage of muddy soft soil increases linearly with the increase of time under certain evaporation conditions.The ratio of maximum vertical line shrinkage to maximum lateral line shrinkage of silt soft soil is a certain value,and the shrinkage of silt soft soil line is divided into linear contraction phase,curve transition stage and near horizontal linear stage with the shrinkage characteristic curve of water content,and the line shrinkage of the linear contraction phase is independent of the initial water content.Secondly,through the investigation of soil moisture content in the soil base surface in the reclamation area,the curves of the curve variation of the near surface and certain depth of soil moisture in the near sea and the vertical direction of the coastline are obtained,which is used as the engineering basis for loading the initial moisture field of soil foundation.Based on the natural conditions of the coastal soil foundation and the actual condition of the road,a soft soil subgrade finite element analysis model including the pavement structure is established.The evolution law of the moisture field of the soft soil under the conditions of evaporation and dry and wet cycle is analyzed by using the SEEP/W finite element software.The results show that in the short term,the humidity of the soil foundation and subgrade soil decreases rapidly under extreme evaporation.Under dry and wet conditions,after 5 years of dry and wet action,the depth of soil moisture disturbed zone is approximately 6m below the surface,and the decrease of humidity slows with the increase of depth.Subgrade soil is affected by water seepage on both sides of subgrade,which is slightly higher than its initial humidity.Finally,according to the similarity between the humidity stress field and the temperature stress field,the soil foundation subgrade finite element model is established by Abaqus,and the relationship between the soil moisture field and the longitudinal relative position of the subgrade is considered,and the influence of the soil base variable humidity field on the subgrade,including the stress and deformation of the pavement structure is studied by numerical simulation.The results are as follows:(1)The decrease of the whole soil humidity field caused the change of the humidity stress field of the soil foundation,which caused the soil foundation to be towed towards the inland low humidity direction;(2)The region of the road structure with larger bottom tensile stress distribution is distributed in the local area on both sides of the subgrade cross section,showing a "double hump" type;(3)The position of the maximum tensile stress occurs near the boundary of the lateral lane and the shoulder of the earth;(4)When the roadbed and humidity field are skewed at a large angle,the lateral maximum additional tensile stress of the roadbed and pavement structure in high humidity area will increase significantly. |
