大厚度湿陷性黄土地层浸水条件下承载桩基对近距隧道的影响研究

发布时间：2018-08-04 21:45

【摘要】：承载桩基对近距隧道具有明显的附加荷载作用,对于水敏性的大厚度湿陷黄土地层其影响更加明显。为系统研究桩基对近距隧道的影响,基于改进的离心浸水试验系统开展考虑不同桩端荷载、不同桩距比和不同地层浸水厚度影响下,承载桩基对近距隧道影响的离心模型试验。试验结果表明:(1)桩基附加荷载致使衬砌结构受力重分布,桩周土体对荷载传递具有削弱作用,桩端荷载越大,削弱作用越明显;土层浸水降低了其承载力,加剧了桩隧间的荷载传递作用;随桩距比增大,桩基对隧道影响逐渐减小。(2)桩端荷载较小时隧道弯矩变化均匀,随荷载增加隧道向桩基方向发生扭曲,荷载进一步增加,隧道扭曲作用加剧;桩距比较小时,增大桩距比对弯矩变化影响减弱较明显,随桩距比增大,进一步增加桩距比对弯矩影响逐渐减小;土层浸水厚度较小时,受桩周土体的荷载削弱作用,桩基对隧道的影响较小,随浸水深度的增加,桩周土体承载力减弱,桩基对隧道的影响随之增加。(3)桩距比为1时,随桩端荷载的增加隧道最大下沉值达到16.7 mm,水平位移达到3.2 mm,随桩距比增加,隧道下沉和水平位移值均减小;随浸水厚度减小,隧道整体位移也减小,地基浸水导致的隧道位移主要表现为下沉,且浸水深度对隧道位移的影响弱于桩端荷载和桩距比。
[Abstract]:The bearing pile foundation has obvious additional load effect on the short-distance tunnel, especially on the large thickness of water-sensitive collapsible loess layer. In order to systematically study the influence of pile foundation on the short distance tunnel, the centrifugal model test was carried out based on the improved centrifugal immersion test system, which considered the influence of different pile end load, different pile-spacing ratio and different stratum immersion thickness on the influence of pile foundation on the short distance tunnel. The test results show that: (1) the additional load of pile foundation causes the stress redistribution of the lining structure, and the soil around the pile weakens the load transfer, the greater the load at the pile end, the more obvious the weakening effect, the lower the bearing capacity of the soil soaking, The influence of pile foundation on tunnel gradually decreases with the increase of pile-spacing ratio. (2) the bending moment of tunnel changes uniformly when the load at pile end is small, and the tunnel warps to pile foundation with the increase of load, and the load increases further. With the increase of pile-spacing ratio, the influence of moment on bending moment decreases gradually, and the influence of soil soaking is small, and the influence of pile spacing ratio on bending moment decreases gradually with the increase of pile-spacing ratio, and the influence of pile spacing ratio on bending moment decreases gradually when the pile-spacing ratio is small, and when the pile-spacing ratio increases, The influence of pile foundation on the tunnel is small due to the weakening of soil load around the pile. With the increase of the depth of flooding, the bearing capacity of the soil around the pile decreases, and the influence of the pile foundation on the tunnel increases. (3) the pile-spacing ratio is 1, With the increase of pile load, the maximum subsidence and horizontal displacement of the tunnel reach 16.7 mm and 3.2 mm respectively. With the increase of pile-spacing ratio, the tunnel subsidence and horizontal displacement decrease, and with the decrease of the immersion thickness, the overall displacement of the tunnel also decreases. The tunnel displacement caused by the soaking of the foundation is mainly shown as subsidence, and the influence of the depth of soaking on the displacement of the tunnel is weaker than that of the pile end load and pile-spacing ratio.
【作者单位】：长安大学公路学院;中铁第一勘察设计院集团有限公司;
【基金】：中铁第一勘察设计院科技项目(YK13 21 1)~~
【分类号】：U452.11

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