Experimental Study On Mechanical Properties Of Hydraulic Engineering Asphalt Concrete

As the anti-seepage system of earth-rock dams,asphalt concrete core wall hasbeen widely used around the worldwide.However,as the new anti-seepage structure ofhydrostructure and the main structure of the dam anti-seepage,the requirements ofsecurity and stability of the asphalt concrete core wall must be paid much moreattention.So it is impotant to study basic mechanical properties of the asphalt concretecore wall material.In this paper,we have studied strength and deformationcharacteristics of asphalt concrete core wall materials under different conditionsthrough the static triaxial tests. Through the study, we have got some regularitymechanical properties of asphalt concrete core wall, and also recognized the workmechanism of asphalt concrete core wall.The main research results as follows:1. As the earth-rock dams with asphalt concrete core is the thesis of this paper,the present situation of design and construction is introduced systematical andmeanwhile, summarized the previous results and the lack of research on themechanical properties of asphalt concrete aspects.On this basis,we made a series oftriaxial tests in different shaping method,different temperatures and different loadingrate to study basic mechanical properties of asphalt concrete, and laid the foundationfor engineering applications.2. This paper used orthogonal test method to deal with the factors,which usedfewer experiments to get the best proportion and the primary and secondaryrelationships of various factors. And the use of poor analysis of the test results wereanalyzed to obtain a test target mix, the introduction of asphalt concrete primariesratio test for the orthogonal algorithm provides a scientific basis.3. The mechanical properties of asphalt concrete is rather sensitive totemperature,confining pressure,etc.Under the same test conditions, the testtemperature is lower, the breakdown strength of asphalt concrete is higher, and theinitial tangent modulus is greater, the axial failure strain is smaller; the confiningpressure is higher, the breakdown strength of asphalt concrete is higher, the dilatancyof sample is less.4. Under the conditions in the same asphalt concrete mix,test temperature andconfining pressure,the isostatic shaping sample’s peak intensity of the (σ1-σ3)～ε1curve is higher than compaction shaping sample’s.And also the initial tangentmodulus is greater, the dilatancy of sample is more pronounced.5. Effect of shear rate on the asphalt concrete triaxial tests showed a similarregularity under different confining pressure test conditions: the shear rate is faster,the breakdown strength of asphalt concrete is higher; breakdown strength almost has asame growth rate with the confining pressure growing under different confiningpressures;and the sample dilatancy is more obvious with the shear rate increasing.6. The asphalt concrete core wall is a hidden structure as the impervious body. Atpresent, the study of the impact of the mechanical properties of asphalt concrete undercyclic conditions of the natural environment temperature variation for asphaltconcrete core wall is also less.In this paper, we simulatied the conditions oftemperature in the thermal cycling on asphalt concrete samples,and reflected the changes of the mechanical properties of asphalt concrete samples by triaxial shear test.The test results showed that asphalt concrete samples’s breakdown strength has bothbeen reduced after temperature cycling.7. Finally Duncan-Chang model,Feng Jia ji correction hyperbolic model andNanshui nonlinear model was adopted to describe the characteristics of thestress-strain relationship of the asphalt concrete and compared with eachother.Thecomparative results indicated that the Nanshui nonlinear model seemed better todescribe the stress-strain relationship of the asphalt concrete.