An attempt has been made to examine numerically, based on an elasto-plastic finite elements (FE) analysis, soil unit weight-ground displacement response due to laying of single and twin circular tunnels which are supported by an internal isotropic pressure (${\sigma }_{\text{i}}$); the case ${\sigma }_{\text{i}}\text{= 0}$ implies an unsupported tunnel. The soil mass has been assumed to be linearly elastic and perfectly plastic obeying the Mohr-Coulomb (MC) yield criterion and an associated flow rule. The stability numbers, corresponding to ultimate collapse, based on lower and upper bound finite elements limit analysis (FELA) have also been separately evaluated. The effects of cover (H) to diameter (D) ratio, spacing (S) to diameter ratio of the tunnels and soil internal friction (ϕ) angle on the results have been examined in detail. The study clearly reveals that the value of the non-dimensional loading parameter, $\frac{\gamma \mathit{\text{D}}}{\mathit{\text{c }}\text{+}{\sigma }_{\text{i}}}$, corresponding to given surface vertical settlement (s_v) and that at ultimate collapse, with an assumption that the elastic and plastic material parameters do not vary with depth, increases continuously with an increase in the values of S/D as well as ϕ, but decreases with an increase in the magnitude of H/D. The obtained computational results were found to compare well with the data reported in literature. It is expected that the study will be useful for stability evaluation and estimating vertical ground settlements for single and twin tunnels.

已尝试基于弹塑性有限元 (FE) 分析数值研究由于铺设由内部各向同性压力支撑的单圆和双圆隧道引起的土壤单位重量-地面位移响应。${\sigma }_{\text{一世}}$); 案子${\sigma }_{\text{一世}}\text{= 0}$意味着一个不受支持的隧道。土体被假定为线性弹性和完美塑性，遵守莫尔-库仑 (MC) 屈服准则和相关的流动规则。基于下限和上限有限元分析 (FELA) 的与最终坍塌相对应的稳定性数字也已单独评估。详细研究了覆盖层（H）与直径（D）比、隧道间距（S）与直径比和土壤内摩擦（φ）角对结果的影响。研究清楚地表明，无量纲载荷参数的值，$\frac{\gamma \mathit{\text{D}}}{\mathit{\text{C }}\text{+}{\sigma }_{\text{一世}}}$，对应于给定的表面垂直沉降 ( s _v ) 和在最终坍塌时，假设弹性和塑性材料参数不随深度变化，随着S / D和ϕ值的增加而连续增加，但随着H / D大小的增加而减小。发现获得的计算结果与文献中报道的数据很好地比较。预计该研究将对单隧道和双隧道的稳定性评估和估计垂直地面沉降有用。