【摘要】 针对高填土荷载作用下沟槽式拱形明洞结构受力研究较少问题,文章首先通过室内模型试验研究了沟槽式高填黄土拱形明洞受力特性,得到了明洞周围土压力分布形式以及拱圈外侧应力随填土高度的变化规律。结果显示,明洞顶曲线段土压力呈"中间大、两边小"分布特征。当填土较低(<1.2倍洞径高度)时,明洞竖向等效均布荷载大于规范值。而当填土较高(≥1.2倍洞径高度)时,明洞竖向等效均布荷载小于规范值。随着填土高度的增加,明洞两侧水平土压力由"正梯形"分布向"矩形"分布转变。明洞底土压力呈"均布荷载"分布。随着填土高度的增加,拱肩截面外侧应力变化较小,而拱顶、侧墙及拱底截面外侧应力显著增加;然后对试验过程进行数值模拟分析。结果显示,明洞周围土压力平均相对误差为11.3%,外侧应力平均相对误差为14.5%,可验证试验数据的正确性及计算参数的合理性;最后进一步探讨了填土高度、沟槽边坡坡角、填料性质和沟槽与明洞宽度比等参数的敏感性对明洞衬砌结构内力的影响。结果表明,沟槽边坡坡角、沟槽与明洞宽度比影响最大,实际工程中应尽量提高边坡坡角,降低沟槽与明洞宽度比,以期改善明洞结构受力。更多还原

【Abstract】 As for few studies on the stress state of the arched open cut tunnel under high backfilling,the mechanical characteristics of high-filled open cut tunnels with arched cross-section in the cutting trench is studied through laboratory tests,the earth pressure distributions around open cut tunnel and stress variations outside tunnel arch ring along with backfilling height are obtained.The results show that the earth pressure distribution at the arched section on the top of open cut tunnel is in the shape of being large in the middle and small on both sides.When the backfilling height is low(less than 1.2 times of the tunnel height),the equivalent vertical uniform load is greater than the value specified in specifications,while being less than this value specified in specifications when the backfilling is high(equal to or greater than 1.2 times of the tunnel height).With the increase of backfilling height,the distribution pattern of earth pressure on both sides of open cut tunnel changes from "positive trapezoid" to "rectangular",and the earth pressure on bottom of open cut tunnel is uniformly distributed.With the increase of backfilling height,the external stress of the section at the spandrel varies little,but increases obviously at the vault,side wall and the bottom of the open cut tunnel.Subsequent numerical simulation analysis shows that the average relative error of earth pressure around open cut tunnel is 11.3%,and the average relative error of external stress is 14.5%,verifying the correctness of experimental data and the rationality of the numerical simulation parameters.Finally,the effects on the internal force of lining structure induced by sensitivity of the influential factors are discussed,such as the backfilling height,slope angle,backfill properties and the trench-width ratio.The results show that the slope angle and trench-width ratio have the most significant effect on the internal force of lining structure.To improve the mechanical properties of the open cut tunnel in the practical engineering,the slope angle should be increased,and the trench-width ratio should be reduced as much as possible.更多还原