高速公路拓宽方式对路基沉降的影响

为了研究高速公路拓宽方式对路基沉降的影响,结合西潼高速公路改扩建工程,针对单侧拓宽和双侧对称拓宽方式建立了路基沉降数值模型,利用有限元方法分析了路基顶面沉降、差异沉降与坡脚水平位移的变化规律,并选定试验段进行双侧对称拓宽方式下的数值模拟分析和分层总和法计算,同时进行了路基沉降观测。分析结果表明:拓宽相同宽度时,双侧拓宽的旧路基中心沉降减小幅度较单侧拓宽增加15.2%;两侧各拓宽2车道时,路基差异沉降是单侧拓宽4车道时的24.3%;随着拓宽宽度的增加,旧路基中心沉降增量逐渐减小,最大沉降位置在距新建路基边缘内侧3～5m处。数值模拟、分层总和法计算及现场观测最大沉降分别为18.40、18.74、16.06mm,表明数值模拟方法可靠,模拟结果与观测结果基本相符。

Influence of widening modes on subgrade settlement of expressway

In order to research the influence of widening modes on subgrade settlement for expressway,the numerical models of subgrade settlement on the unilateral and bilateral symmetry widening modes of Xitong Expressway were set up,the change rules of top surface settlement,differential settlement and horizontal displacement of slope toe for subgrade were analyzed by using the finite element method,and the comparison result of numerical simulation values,layer-wise summation method’s computation values and observation values for subgrade settlement in bilateral symmetry widening mode was analyzed.Analysis result indicates that when the widening widths are same,the decrease amplitude of settlement for old subgrade center in bilateral widening mode is 15.2% larger than the value in unilateral widening mode.The difference of subgrade settlement in widening 2 lanes on both sides is 24.3% of the value in broadening 4 lanes on one side.With the increase of widening width,the center settlement increment of old subgrade decreases gradually,and the displacement of the maximum settlement to the inside of new subgrade edge is 3-5 m.The maximum settlements from numerical simulation,layer-wise summation method and field observation are 18.40、18.74 and 16.06 mm respectively,which indicates that the numerical simulation method is reliable,and the simulation conclusion and the observation result are consistent.