不同埋深下墙脚缺陷对砂性地层隧道影响研究

Study on the influence of wall foot defects on tunnel in sandy stratum under different buried depths

隧道墙脚在施工中容易形成质量缺陷,可能会对隧道结构造成损害,为研究在不同埋深砂性地层条件下墙脚缺陷对隧道结构的影响程度,基于模型试验结果结合数值模拟手段确定缺陷对衬砌结构的弱化程度,并在此基础上拓宽埋深范围,进一步分析缺陷对隧道结构受力以及结构安全状态的影响。结果表明:墙脚缺陷对衬砌结构受力影响有限,墙脚以及仰拱受到的影响大于隧道其他位置;随着隧道埋深的增加,墙脚缺陷处弯矩值由负变正,同时拱脚、拱底的弯矩增幅明显;隧道埋深由2.5倍洞径增加到3倍洞径时,衬砌各个位置的安全系数出现不同程度的减小,其中仰拱的安全系数减幅最大,使之成为隧道结构破坏的重点区域。

Tunnel footing is prone to form quality defects during construction, which may cause damage to the tunnel structure. In order to study the influence of wall foot defects on tunnel structure under different buried depths of sandy stratum, the weakening degree of defects on lining structure is determined based on model test combined with numerical simulation. On this basis, the buried depth range is widened, and the influence of defects on tunnel structure stress and structural safety state is further analyzed. The results show that the influence of wall foot defects on the lining structure is limited, and the influence of wall foot and inverted arch is greater than that of other locations of the tunnel. With the increase of tunnel depth, the bending moment of wall foot changes from negative to positive, and the bending moment of arch foot and arch bottom increases obviously. When the buried depth of the tunnel increases from 2.5 times the hole diameter to 3 times the hole diameter, the safety factor of each position of the lining decreases in varying degrees, and the safety factor of the inverted arch is the largest, which makes it the key area of the tunnel structure damage.