地裂缝活动环境下盾构隧道双层衬砌性状分析

 处于地裂缝活动环境下的盾构隧道，在地裂缝上下盘相对错动下，隧道衬砌在纵向将承受比正常情况下大得多的附加应力和变形，此时衬砌在结构强度和防水两个方面都可能失效，使隧道不能正常运营。基于此，考虑在盾构隧道混凝土管片衬砌内再作一层整体式现浇钢筋混凝土内衬形成双层衬砌结构，共同承担外力，以达到减小结构应力和变形的目的。为此，对双层衬砌结构在地裂缝作用下的受力和变形性状进行数值分析，主要考虑地裂缝上下盘错距、钢筋混凝土内衬厚度和强度等因素对衬砌受力和变形性状的影响，得出一些具有工程指导意义的结论，计算结果表明：管片内的整体式钢筋混凝土内衬能有效的减小隧道衬砌在地裂缝错动下的内力和变形；衬砌的内力和变形与地裂缝错距大致成线性正比关系；内衬厚度对衬砌受力和变形均有较大影响，衬砌越厚，应力和变形越小，但厚度超过300 mm后再增加厚度，效果明显减弱；内衬强度对衬砌受力和变形的影响较小，实际工程中采用C30混凝土即可。

ANALYSIS OF DOUBLE-LAYERED LINER BEHAVIORS OF SHIELD TUNNEL UNDER ACTIVE MOVING GROUND-FISSURES

The shield tunnel under the environment of moving ground-fissures will bear additional stress and deformation which are larger than those of normal condition when subjected to the relative moving of ground-fissures. so，the tunnel-lining will lose the function both in the aspects of strength and watertight. In this paper，a kind of double-layered lining which casts an integral reinforced concrete internal lining inside duct pieces，is developed to co-bear the additional loads and reduce the stress and deformation of structures. Numerical analysis is performed to analyze the double-layered lining behavior of stress and deformation subjected to the actions of ground-fissures. The relative moving distance，the strength and thickness of inner lining are the main influencing factors，and some conclusions with guiding significance to practical engineering are drawn. The results show that the integral reinforced concrete internal lining inside duct pieces can effectively reduce the stress and deformation of the tunnel-lining；the stress and deformation of the lining has linear proportion with the relative distance of ground-fissures；the thickness of the internal liner has great impact on the stress and deformation of the lining，and the stress and deformation of the lining become smaller when there is bigger thickness of the internal lining，but when the thickness of the internal lining exceeds 300 mm，there only exists weaker influence with the increase of the thickness；The strength of inner lining has smaller impact on the stress and deformation of the liner，and in the specific engineering C30 concrete is enough.