路桥过渡段填料中动荷载传递特性

为研究动荷载在路桥过渡段级配碎石填料中的传递规律,在路桥过渡段填筑过程中分别布设了3层土压力盒,各层均按梅花形布设,对压路机往返压实过程与液压夯夯击过程中各点应力进行实时监测,分析了压路机的振动荷载与液压夯的冲击荷载在同一填筑平面的传递特征; 进一步将竖直方向的各层测点元件拟定为对应的荷载传递路径,以此分析了各条路径中动荷载竖向传递规律。结果表明:填料的压实或夯击遍数直接影响动荷载的传递特性,随着压实或夯击遍数的增加,压力盒测得的应力值逐渐增大; 随着夯击遍数的增加,同一深度处填料的相对应力增加量均呈台阶状递增; 压路机与液压夯产生的动荷载在填料中的荷载衰减量随着深度增加逐步递减; 填料经过压路机与液压夯的6遍压实与夯击后,同一深度处的冲击荷载增加量为振动荷载增加量的4倍左右,液压夯处理路基填料的效果尤为显著; 试验结果为今后级配碎石填筑路桥过渡段提供了现场测试方案,为后续施工提供了理论指导,使现场测试环节更加完善。

Characteristics of Dynamic Load Transfer in Packing at Bridge-subgrade Transition Sections

In order to study the rules of dynamic load transfer in graded gravel packing at bridge-subgrade transition sections, 3 layers of earth-pressure cells during the filling process at the bridge-subgrade transition section were set up, each layer was arranged according to quincunx type. Through real-time monitoring of the stress at different points during the road roller compacting process and the hydraulic rammer tamping process, the transfer characteristics of vibrating load and impact load of the road roller were analyzed on the same filling plane. By further fixing the cells on each layer in the vertical direction as the corresponding path of load transfer, the rules of vertical transfer of dynamic load in each path were also studied. The results show that the compaction degree of filler or the number of tamping directly affect the transmission characteristics of the dynamic loads. The stress value measured from the pressure cell increases with the compaction degree or the tamping number increasing. The increments of relative stress make a stepladder like increase with the number of tamping increasing at the same depth of the filler. The load attenuation of dynamic load generated by roller and hydraulic rammer in the filling decreases with the depth. After six times of compaction by roller and hydraulic rammer, the increase of impact load at the same depth is about four times of the increase of vibration load, and the effect of hydraulic ramming on subgrade filling is particularly significant. The experiment provides an on-site test plan for future bridge-subgrade transition sections filled with graded gravel, and a theoretical guide for subsequent construction, it will further complete on-site testing.