摘要
为探明山区沟谷地形对高填方盖板涵受力特性和填土沉降变形特性的影响,通过离心模型试验,选用自主研发的能够反映地形-涵洞-填土相互作用的模型试验平台,分析了不同沟谷宽度B和不同沟谷坡度α下盖板涵的涵-土界面土压力、涵顶填土沉降变形、涵洞结构内力以及涵顶垂直土压力集中系数K_s的变化特征,并提出了相关的工程技术建议。研究结果表明:涵-土界面土压力、涵顶垂直土压力集中系数K_s与沟谷宽度呈正相关,与沟谷坡度呈负相关;盖板涵涵顶土体沉降变形呈W形分布,随沟谷宽度的增大,涵顶土体内外沉降差δ逐渐增大;随沟谷坡度的增大,涵顶土体内外沉降差变化为δ→0→-δ;沟谷宽度为1.5D～5D时(D为涵洞计算跨径),对应等沉面高度变化范围为12.2～13.7 m;沟谷坡度为0°～60°时,对应等沉面高度变化范围为12.5～13.7 m,提出可用等沉面高度界定高填方涵洞,可取14 m作为其界定高度;盖板涵盖板下缘、涵底上缘中部受拉应力,盖板下缘为盖板涵结构受力最不利位置;高填方盖板涵施工时应充分利用原有地形,在确保边坡稳定的前提下,尽量保留边坡,或人为反开挖施工,增加沟坡、减小沟宽,坡体以沟谷宽度B≤3D、沟谷坡度α≥45°为宜。
To study the influence of the gully topography on the stress of high fill slab culverts and settlement characteristics of the fill, a centrifugal model test was carried out, using a self-developed model test platform which can reflecting the interactions among the topography, culvert, and fill. The variation characteristics of the earth pressure of the culvert-soil interface, fill settlement, internal force of the culvert structure, and the vertical soil pressure concentration coefficient K_s under different valley widths B and different valley slopes α were analyzed. Furthermore, relevant engineering technical recommendations were presented. The results show that the earth pressure of the culvert-soil interface and the vertical soil pressure concentration coefficient K_s are positively correlated with the valley widths, and are negatively correlated with the valley slopes. The settlement of the fill at the culvert top shows a W shaped distribution. With an increase in the valley widths, the difference between the internal and external settlements of the soil increases gradually. Further, with an increase in the valley widths, the settlement δ of the fill gradually increases. With an increase in the slopes of the valley, the settlement difference between the inside and outside of the fill is δ→0→-δ. When the gully width is 1.5D to 5D, where D is the culvert span, the range of change in the equal settlement section height is 12.2 to 13.7 m. When the gully slope is 0° to 60°, the range of change in the equal settlement section height is 12.5 to 13.7 m. Moreover, the equal settlement section height is used to determine whether the culvert is a high fill culvert, and 14 m is taken as the defined height. The lower edge of the cover plate and the middle of the upper edge of the culvert floor are subjected to a tensile stress, and the lower edge of the cover plate is the most unfavorable position of the slab culvert structure. The construction of high fill slab culverts can make full use of the original topography. Under the premise of slope stability, to retain the gully as far as possible, or to apply anti-excavation construction methods, artificially increase the gully gradient and reduce the gully width. A gully width of B≤ 3D and a gully slope of α≥45° are advisable. 3 tabs, 17 figs, 26 refs.
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