Experimental Research on Incoordinate Deformation Between Existing Subgrade and the Widening One

The incoordinate deformation between the existing subgrade and the widening one essentially results in many distresses in road widening engineerings.So how to control this deformation is the key point in these subgrade treatments.During the laboratory test,a certain thick layer of soluble ammonium sulphate was placed at the bottom of the widening subgrade.After filling was completed,this layer was dissolved,thus simulating this incoordinate deformation.During the test,a certain thick of the common subgrade layer was constructed,and two layers of geogrid were laid.The test shows that a common layer between the existing subgrade and the widening one distinctively alleviates this discrepant after-construction settlement,and the geogrid-reinfocing treatment evidently decreases the soil pressure on ground base surface,consequently it reduces the incoordinate deformation.