公路隧道下穿铁路路基的沉降行为研究

对公路隧道下穿铁路路基拓宽改造后新老路基的沉降行为和路面结构变形机制进行了研究。结果表明,公路隧道下穿铁路路基拓宽改造后的路径不同区域的路基沉降在位移达到16~20 cm时基本趋于稳定,柔性位移计监测得到的土工格栅位移伸缩量(约2 mm)远小于破坏极限值;加土工格栅对路基路面沉降效果影响较小,但是可以对基层的附加应变起到抑制作用,从而缓解差异沉降。无论是上面层、中面层还是下面层,无荷载、静荷载、动荷载和卸载后的应变都随着距离旧路基中心线距离的增加而先增加至峰值而后逐渐减小,且应变峰值都未出现在新旧路基连接处,而是在距离路基连接处约1 m位置。

Study on Settlement Behavior of Highway Tunnel Passing Through Railway Subgrade

The settlement behavior of the new and old subgrade and the deformation mechanism of the pavement structure after the widening and reconstruction of the railway subgrade under the highway tunnel are studied.The results show that the settlement of Subgrade in different areas of the road tunnel under the Railway Subgrade after widening and reconstruction basically tends to be stable when the displacement reaches 16-20cm,and the displacement and expansion of geogrid(about 2mm)monitored by the flexible displacement meter is far less than the damage limit value;geogrid has little effect on the settlement of subgrade and pavement,but it can restrain the additional strain of the base.So as to alleviate differential settlement.No matter the upper layer,the middle layer or the lower layer,the no-load,static load,dynamic load and the strain after unloading all increase to the peak value first and then decrease gradually with the increase of the distance from the center line of the old subgrade,and the peak value of strain does not appear at the connection of the new and old subgrade,but at about 1m from the connection of the subgrade.