现浇成型综合管廊不均匀沉降裂缝分析--以福州东南快速通道综合管廊为例

Analysis on Cracks of Cast-in-Place Utility Tunnel Induced by Uneven Settlement:a Case Study of Utility Tunnel of Fuzhou Southeast Freeway

城市综合管廊作为城市正常运作的生命线工程,其结构开裂不仅影响外观,而且会带来地下水渗漏问题,降低结构及相关设备的耐久性。以福州东南快速通道综合管廊为例,为研究管廊结构开裂的原因,对管廊施工期沉降监测数据进行分析,并采用有限元法及裂缝扩展有限元法进行数值模拟,得出结论:1)试验段管廊施工时,管廊地基土体出现流失,造成后期管廊不均匀沉降和变形缝错台,这是引起大里程段管廊开裂的根本原因;2)压重混凝土施工后,大里程段出现不均匀沉降,管廊中部K3+917位置附近顶板局部拉应力超过混凝土抗拉强度标准值,顶板出现初始裂缝;3)随着变形缝两侧管廊沉降差增大,变形缝错台,出现涌水涌砂,顶板裂缝向中墙和侧墙扩展。

Utility tunnels are typically regarded as lifelines of a city,whereas the cracks of the utility tunnel structure affect the appearance,cause groundwater leakage,and reduce the durability of the structures and related equipment.In order to explore the causes of cracking of the utility tunnel of Fuzhou Southeast freeway in China,the settlement monitoring data of the utility tunnel during construction are analyzed,and the finite element method of crack propagation is used for numerical simulation.Conclusions are drawn as follows:(1)During the construction of the utility tunnel in the test section,the soil loss occurred in the foundation,resulting in the uneven settlement of the utility tunnel and the dislocation of deformation joints,which is the root cause of the utility tunnel cracks in the large-mileage section.(2)After constructing the compacted concrete,an uneven settlement occurred in the large-mileage section,and the local tensile stress of the roof near section K3+917 in the middle of the utility tunnel exceeds the standard value of concrete tensile strength,resulting in roof cracks.(3)The deformation joints dislocated with the increase in the settlement difference of the utility tunnel on both sides of the deformation joint,causing water and sand gushing and the expansion of roof cracks toward the middle and sidewalls.