铁路隧道复合衬砌脱空的危害分析与防治

The Hazard Analysis and the Treating Measures of the Voids in the Composite Linings of Railway Tunnels

铁路隧道复合衬砌脱空和支护厚度不足占隧道缺陷、病害的比例极高。以200km.h-1客货共线双线隧道为例,采用ANSYS有限元分析软件,按"共同变形"受力模型计算分析脱空对结构承载能力的影响。初支脱空时,在不同级别围岩变形压力的作用下,初支拱顶部位向内侧压弯呈增大趋势,这是初支向内压裂(碎)乃至坍塌的主要原因之一;衬砌脱空时,导致衬砌拱顶部位向外侧或向其对应的空洞边缘外侧压弯呈增大趋势,造成衬砌向外压裂甚至可能引起脱空水平投影范围外沿侧纵向开裂。严重的脱空可能导致隧道结构在施工阶段或运营阶段发生压溃、侵限、放射状开裂和坍塌,而且初支脱空的危害性比衬砌脱空更大。通过分析脱空的形态和成因,结合工程实践经验,从施工和施工管理角度提出了脱空防治的具体措施和建议。

The voids in the composite lining of railway tunnel and the deficiency of the support thickness take up very high proportion of tunnel defect and disease.Taking a double-track tunnel of 200 km·h-1 passenger and freight railway as an example,using ANSYS finite element analysis software,the influence of the voids on the structural bearing capacity is calculated and analyzed according to the ＂common deformation＂ force model.When there are voids between the primary support and the surrounding rocks,under different deformation stress of surrounding rock,the inward compression bending at the vault of the primary support tends to increase,which is one of the main causes resulting in the inward crack（crush） and even the collapse of the primary support.When there are voids between the primary support and the secondary lining,the outward compression bending at the vault of the secondary lining or at its corresponding void edge tends to increase,which gives rise to the outward crack of the secondary lining and even may lead to the lateral and longitudinal crack at the outer zone of the void horizontal projection area.Serious voids may result in the crushing,beyond-limit deformation,radial crack and collapse of the tunnel structure during construction or service stage,and the harmfulness of void between the primary support and the surrounding rocks is more serious than that of the void between the primary support and the secondary linings.By analyzing the forms and causes of voids,in association with the experiences of engineering practices,concrete measures and suggestions for the prevention and treatment of voids are put forward from the angles of construction and construction management.