摘要:
当今盾构隧道的建设规模愈发庞大，洞身穿越的地层复杂多变，单层管片衬砌结构往往难以满足隧道安全性和耐久性要求，由此双层衬砌结构得到了更加广泛的关注。为探究不同地层中盾构隧道双层衬砌结构的适用性，依托广深客运专线狮子洋盾构隧道工程，通过相似模型实验，以侧压力系数（0.5、0.6、0.7、0.8）为指标对比分析了不同地层条件下双层衬砌结构力学特性的变化规律。试验结果表明：地层侧压力系数增大，双层衬砌整体更加趋于静水压力场状态，管片衬砌与二次衬砌极限轴力值增大，弹塑性临界点与内力突变点滞后。当侧压力系数从0.5增至0.8时，双层衬砌的极限承载能力提升了66.39%，最大径向位移从15.17mm减小为9.45mm，管片衬砌侧向位移受限，二次衬砌辅助管片衬砌承载能力提升。高地层侧压力条件下管片衬砌裂纹发育程度下降，局部掉块现象减少，双层衬砌整体结构的可靠性提升。
Abstract:
Nowadays, the construction scale of shield tunnels is getting bigger and bigger, and the strata crossed by the tunnel body are complicated and changeable, so it is often difficult to meet the requirements of tunnel safety and durability with single-layer tube lining structure, and thus the double-layer lining structure has been more widely concerned. In order to explore the applicability of double-layer lining structure of shield tunnel in different strata, relying on the Shiziyang Tunnel Project on the Guangzhou-Shenzhen High-Speed Railway, the change rule of the mechanical properties of double-layer lining structure under different strata conditions is comparatively analyzed with the coefficient of lateral pressure (0.5, 0.6, 0.7, 0.8) as an index through similar model experiment. The test results show that: the stratum lateral pressure coefficient increases, the double-layer lining as a whole tends to be more hydrostatic pressure field state, pipe lining and secondary lining limit axial force value increases, elasticity and plasticity critical point and the lagging of the internal force mutation point. When the lateral pressure coefficient increases from 0.5 to 0.8, the ultimate bearing capacity of double-layer lining increases by 66.39%, the maximum radial displacement decreases from 15.17mm to 9.45mm, the lateral displacement of pipe sheet lining is limited, and the secondary lining assists in the improvement of bearing capacity of pipe sheet lining. The degree of crack development of pipe sheet lining under high stratum lateral pressure condition decreased, the phenomenon of localized falling block was reduced, and the reliability of the overall structure of double-layer lining was improved.
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