盾构隧道环间纵向压力时变规律研究

盾构隧道断面上受到纵向压力的大小,一方面影响环缝止水垫的防水性能;另一方面影响环缝刚度,从而影响隧道纵向不均匀沉降的发展。目前实际工程中主要依据经验估测隧道中残留的纵向力。通过求解描述隧道受力变形特征的微分方程,建立了隧道任意断面纵向力随时间的变化关系,并将理论解与现场试验实测结果进行了对比,二者具有良好的匹配性。研究结果表明,隧道纵向力在波动中下降,最终残留的纵向力大小与混凝土徐变系数和周围土体的压缩模量有关,约为掘进阶段千斤顶顶力的20.4%~44%。

Temporal variation laws of longitudinal stress on cross section of shield tunnels

The longitudinal stress acting on the cross section of shield tunnels will affect the waterproof properties of the segments and the stiffness of the circumferential joints,which will thus affect the development trend of the longitudinal nonuniform settlements.At present,the longitudinal stress is estimated based on the experience in actual engineering.By solving the differential equation,the temporal variation laws of the longitudinal stress are proposed.The theoretical solution is also compared with meatured data from field experiments,and they matches well.The results show that the longitudinal stress decreases in fluctuations with time.The magnitude of the remaining stress is related to the creep coefficient of concrete and the compression modulus of formation.There is 20.4%~44%of the initial longitudinal stress left.