下穿隧道围岩蠕变对地下人防工程底板受力及变形影响研究

随着城市地铁建设进程加快,地铁隧道下穿人防工程时有发生,隧道和人防工程之间的相互影响成为目前迫切需要解决的问题。由于岩土体具有蠕变特性,研究其蠕变条件下的长期稳定性成为研究热点。采用D-P屈服准则耦合时间硬化率蠕变模型的有限元软件,研究了隧道不同埋深和直径以及穿越地下人防工程时围岩蠕变变形以及人防工程底板弯矩变化规律,弥补了弹塑性分析的不足。人防工程的存在减小隧道拱顶下沉;隧道衬砌减小隧道沉降以及人防工程底板弯矩。隧道埋深越大,隧道与人防工程底板净距值越大,人防工程底板弯矩越小;隧道直径越大,人防工程底板弯矩越大。一定埋深情况下,配筋率越大,最大允许隧道直径越大。埋深15~30 m,直径10~14 m时,隧道拱顶下沉随隧道埋深或直径增大而增大,增幅约为埋深或直径每增大1 m,沉降增加约0.018 m。不同隧道埋深或直径下,隧道拱顶下沉与人防工程底板弯矩呈线性关系。

Stress and deformation of underground engineering floor under effect of surrounding rock creep of tunnel beneath underground engineering

With the construction of urban subway increasing, tunnel cross underground engineering would appear. The mutual influences between tunnel and underground engineering become the urgent problem need to be solved. Due to the creep feature of geotechnical engineering, the long-term stability of underground engineering with creep has become a research hotspot. Drucker-Prager yield criterion couple time hardening model is used to study creep deformation law of the surrounding rock and bending moment of underground engineering in different buried depth and diameter of tunnel cross through underground engineering, modifying the elastoplastic analysis. The existence of underground engineering decreases settlement of tunnel vault. The lining supports structure decreases settlement of tunnel and bending moment of underground engineering. With the buried depth of tunnel increasing, the bending moment of baseboard of underground engineering decreases; with the diameter of tunnel increasing, the bending moment of baseboard increases. In a definite buried depth, the bigger the reinforcement ratio is, the bigger the maximal allowed tunnel diameter is. The settlement of tunnel vault increases with buried depth and diameter increasing. Every 1meter the buried depth or diameter increasing, the settlement of tunnel vault increases 0.018meter, when the depth and diameter are between 15 and 30 meters, 10 and 14 meters, respectively. The relationship between settlement of tunnel vault and bending moment of underground engineering is linear in different buried depth or diameter.