交通荷载作用下低路堤动力特性试验研究

结合连盐高速低路堤,对路堤进行了动应力、振动响应等现场测试,分析了路基中附加动应力及振动位移的变化规律.并且通过应力控制的室内动三轴试验,采用一定的动应力频率、不同的循环应力比来模拟交通荷载,研究了在循环荷载作用下,连盐高速公路饱和软粘土的轴向累计应变、孔隙水压力和轴向周期应变软化的变化规律.实验结果表明:路堤中动应力和振动位移随行车速度和车重的增加而增加,随深度的增加而降低,有效影响深度达2.5 m;原状土的临界循环应力比远大于重塑土,承受循环应力能力高于重塑土.因此,要加强浅层路基强度,同时要减少对底部下卧层软粘土的扰动.其结果可为在软土地基上设计和施工低路堤高速公路提供有益的参考.

Experimental study on dynamic response of low embankment under traffic load

The field tests of dynamic stress and vibration response were conducted at Lianyan expressway with low embankment.The additional dynamic stresses and vibration displacement in roadbed were analyzed.In addition,in laboratory tests using dynamic triaxial test machine with stress controlled,definite dynamic stress frequency and different cyclic stress ratio were adopted to simulate the traffic load,and the axial strain,pore water pressure and axial strain softening under cyclic load were studied.The results show that the dynamic stress and vibration displacement increase with the increase of traffic velocity and weight,and decrease as the depth increases,the effective influence depth being about 2.5 m.Critical cyclic stress ratio of undisturbed soil is bigger than disturbed one.Dynamic shear strain of undisturbed soil exceeds that of disturbed one.Therefore,the strength of shallow subgrade needs to be reinforced and the disturbance of the subsoil during construction needs to be reduced.The result is useful for designing and constructing expressway with low embankment on soft clay.