摘要
在花岗岩风化层中盾构施工时采用压气法可阻止地下水向隧道内渗流,提高掌子面的稳定性,但存在土仓气压稳定控制等问题,因此有必要对压气法盾构施工中空气注入量进行预测。以广州地铁某压气法施工隧道为背景,根据土仓气体超压向前方地层渗透而引起气-水运移和土体气相(液相)饱和度的变化特点,考虑非饱和土中空气和水的传导函数强非线性,利用TOUGH2软件建立了分层均质、各向同性土层的三维有限元模型进行渗流分析,揭示了压气法盾构施工过程地层中的气-水运移基本规律。研究结果表明:超压气体在地层中形成非饱和区并逐步发展,直至与地表联通并形成漏斗状稳定渗流通道;并将模拟的空气损失量和现场实测分析数据进行对比,验证了模型的合理性;最后,通过改变土体固有渗气系数,得到土体固有渗透系数与渗气量呈指数关系,并建议了不同保气土层工况气体注入量。
Tunneling in completely weathered granite and its residual soil ground with compressed air can pre-vent seepage of groundwater into the tunnel and improve the stability of tunnel face. However, some problemsexist such as the air pressure control in head chamber, and it is necessary to evaluate the rate of air loss withshield method using compressed air. In view of compressed air tunneling for a subway tunnel in Guangzhou, according to the characteristics of gas and soil movement in the soil and considering the strongly nonlinear of airand water conduction function in unsaturated soil, a three-dimensional finite element seepage model of layeredhomogeneity and isotropic soil was established by using TOUGH2 software. The basic rule of gas and water mi-gration in the stratum with A-EPB shield method was revealed. The research results show that an unsaturatedzone has been formed and this zone progressively develops with time until it connects with the surface and formsa funnel shaped steady seepage channel. The calculated air losses are within the range from the field date, whichverifies the rationality of this model. Finally, an exponential relationship has been conducted between permeabil-ity coefficient of soil and quantity flow of air seepage, and the air injection quantity of different soil layers hasbeen suggested.
作者
刘训华
赵昱
夏杰
Liu Xunhua;Zhao Yu;Xia Jie(Hongrun Construction Group Co.,Ltd.,Shanghai 200232,China;Key Laboratory of Road and Traffic Engineeringof the Ministry of Education,Tongji University,Shanghai 201804,China)
出处
《华东交通大学学报》
2018年第5期85-93,共9页
Journal of East China Jiaotong University
关键词
盾构隧道
压气法
两相渗流
数值模拟
shield tunnel
tunneling with compressed air
two-phase flow
numerical simulation
