| Rock-fill dam with asphalt concrete core is one of the main dam type.While in the traditional type of rock-fill dam with asphalt concrete core,the core wall and dam shell are both straight.So at runtime,the core will produce elongation distortion under pushed by horisontal water pressure pointing to the downstream,and there are tensile stress and tensile stress areas among asphalt concrete core.It is easy to cause core wall hydraulic fracturing under the upstream water pressure,which is harm to the safety of the dam.In order to reduce or eliminate the tensile stress areas in core and improve the stability of the dam,it is necessary to study the measures of improving mechanical properties of rock-fill dam with asphalt concrete core.（1）Based on the dual trigonometric series solution of the small deflection bending rectangular thin plate with four edges simply supported,winkler elastic foundation beam solution and the theory of elastic foundation curved beam,respectively analyze core wall plate radial displacement along the axis direction of the straight core wall plate and curved core wall plate under the active earth pressure of upstream rockfill,upstream water pressure and passive earth pressure of downstream rockfill.The study shows that the straight core wall under pushed by the upstream water pressure along river,the axis of straight core wall is elongated.Thus the core wall plate exists tensile stress besides compressive stress.While the curved core wall plate under pushed by the upstream water pressure along river,the axis of core wall is compressed.That is to say,the cure core wall is compressed integrally,then the interal tensil stress is reduced or even eliminated.And it is advantageous to the dam body stability.（2）Study the displacement and stress variation characteristics and distribution of the core wall with different proportion of asphalt core wall elastic modulus to rockfill elastic modulus,for straight dam straight core dam type that is traditional asphalt concrete core wall dam under pushed by the horizontal water pressure.The results show that when the asphalt concrete core wall elastic modulus is small,the stress concentration of core wall is weak after forced,which is soft core wall having some ability to release stress.The heart wall is almost entirely internal compressive stress.But with the increasing of elastic modulus of the core wall,the core wall stress concentration is increasing and asphalt concrete core wall near the top of the downstream face gradually appears tensile stress.And the larger the proportion of asphalt core wall elastic modulus to rockfill elastic modulus the greater tensile stress and tensile stress area are.（3）Selecting asphalt concrete core wall elastic modulus 10 times of the rockfill elastic modulus,for three new types of dam that are straight dam with cure core wall(the curvature of core wall is k=8.27×10-4),cure dam with cure core wall(the curvature of dam body is k=8.27×10-4)and cure dam with cure core wall(the curvature of dam body is k=2.46×10-3),study the displacement and stress variation characteristics of the core wall different arching radians under pushed by the horizontal water pressure to determine which the type of dam is most significant on improving the mechanical characteristics of the core wall.The study shows that the dam type of straight dam with cure core wall(the curvature of core wall is k=8.27×10-4)and cure dam with cure core wall(the curvature of dam body is k=8.27×10-4)both have some effects.Due to the arching radians are not enough,the effect of improving the mechanical properties of the core wall is not obvious.For the dam type of cure dam with cure core wall(the curvature of dam body is k=2.46×10-3),the effect of reducing the value of tensile stress and tensile stress area is very remarkable.Under pushed by the horizontal water pressure,the core wall is integrally compressed without tensile stress.At the same time,it can reduce stress concentration phenomenon and arching effect at the bottom of the core wall. |
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