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盾构隧道施工引起的环境土工效应分析一直是隧道及地下建筑工程领域中研究的热点问题。由于目前该领域较少考虑饱和土质以及隧道衬砌与土体间界面排水工况所带来的影响,尤其是较少针对隧道施工长期变形影响以及衬砌应力进行解析分析。由此基于隧道开挖椭圆化变形模式,考虑衬砌界面完全排水以及完全不排水两种工况,提出了饱和土中浅埋隧道开挖引起的地层长短期变形和隧道衬砌应力计算方法。结果表明:椭圆化变形模式对地层短期变形和长期变形的影响均较明显,在此条件下得到的位移曲线与实测值吻合较好。在计算衬砌内力时,衬砌轴力和弯矩整体关于90°/270°轴即隧道竖轴线严格对称,其中轴力沿圆周呈上大圆下小圆的倒“8”字形分布;而弯矩沿圆周呈上下圆基本一致的“8”字形分布,其中下圆稍大。土质和界面排水条件显著影响衬砌内力值的大小,其中饱和土长期排水工况下衬砌内力值一般大于不排水工况解,且其与饱和土短期不排水解相比差距明显。分析成果可为正确预估饱和土浅埋盾构开挖变形提供一定的理论依据。
Environmental geotechnical analysis caused by shield tunnel construction has always been a hot issue in the field of tunnel and underground construction. At present, the influence of the saturated soil quality and drainage conditions at the interface between the tunnel lining and the soil body is less considered in this field, especially the analysis of long-term deformation and longwall deformation of the tunnel construction and the stress of the lining are seldom analyzed. Based on the oval deformation mode of tunnel excavation and considering the complete drainage of the lining interface and the completely undrained conditions, the stratigraphic short-term deformation and the stress calculation of the tunnel lining caused by the excavation of the shallow buried tunnel in saturated soil are proposed. The results show that the effect of the elliptical deformation mode on the short-term deformation and long-term deformation of the formation is obvious. The displacement curve obtained under this condition is in good agreement with the measured value. In calculating the lining internal force, the lining axial force and bending moment are strictly symmetrical with respect to the 90 ° / 270 ° axis, that is, the vertical axis of the tunnel. The axial force is distributed in the shape of “8” Moment along the circumference of the upper and lower circle is basically the same “8 ” glyph distribution, which round slightly larger. Soil and interface drainage conditions significantly affect the lining internal force values, of which the lining internal force value of saturated soil under long-term drainage conditions is generally larger than that under undrained conditions, and the difference between them is not significant compared with that of saturated soil under short-term undrained conditions. The results of the analysis can provide a theoretical basis for correctly estimating the deformation of shallow-buried shield excavations in saturated soils.