考虑隧道周围土体自重应力,建立饱和土体二维非线性固结控制方程,使用交替隐式差分法对方程进行求解.通过将退化解与已有解析解比较,以及将计算结果与工程实测数据对比,验证了解答的正确性.在此基础上,进一步探究了土体自重应力及固结系数变化对隧道周围土体非线性固结特性的影响规律.结果表明:忽略土体自重应力不仅会导致土层的超静孔压偏大,固结沉降速率偏小,还会使地表沉降终值偏小;在自重应力影响下,压缩指数与渗透指数之比C_c/C_k越小,土体固结沉降速率越慢,但地表沉降终值不会改变;当C_c/C_k=1.0时,土体重度越小,其固结速率受初始有效应力分布形式的影响越大,同时地表沉降终值也越大;C_c/C_k >1.0时渗透系数在固结过程中起主导作用,固结速率随重度增大而减小,而C_c/C_k <1.0时体积压缩系数的影响效果增强,固结速率变为随重度增大而增大,但两种情形下的地表沉降终值均随土体重度增大而减小.

Considering the self-gravity stress of the soil around the tunnel, a two-dimensional nonlinear consolidation control equation for saturated soil was established, and solved using the alternating implicit difference method. The correctness of the solution was verified by comparing the degenerate solution with an existing analytical solution, and by comparing the calculated results with measured data. On this basis, the influence of changes in soil self-gravity stress and consolidation coefficient on the nonlinear consolidation characteristics of the soil around the tunnel was further explored. The results indicate that neglecting the self-gravity stress of the soil leads to a higher excess pore pressure and a lower rate of consolidation settlement, and leads to a lower final surface settlement. Under the influence of self-gravity stress, a smaller ratio of compression index to permeability index C_c/C_k results in a slower consolidation settlement rate of the soil, but does not affect the final surface settlement. When C_c/C_k=1.0, a smaller soil self-gravity results in a greater influence of the initial effective stress distribution on the consolidation rate and a higher final surface settlement. When C_c/C_k>1.0, the permeability coefficient plays a dominant role in the consolidation process, and the consolidation rate decreases as the gravity increases. In contrast, when C_c/C_k<1.0, the volume compression coefficient becomes more influential, and the consolidation rate increases with the increase of gravity, though the final surface settlement in both cases decreases with increasing gravity.