富水大断面软岩隧道支护结构受力性能试验

Experiment on Mechanical Properties of Soft Rock Tunnel with Large Section of Water-rich

富水大断面软岩隧道施工具有很大的风险,其支护结构荷载与安全一直是学术界、工程界关注的关键科学问题。以石太客运专线石板山隧道为依托,采用现场试验和三维有限元模拟相结合的方法,研究富水环境下Ⅳ级、Ⅴ级围岩隧道初期支护围岩压力、钢拱架受力、二次衬砌背后水压和接触压力分布特征。研究表明:富水大断面软岩地层隧道围岩压力分布不均匀,传统的普氏理论、泰沙基理论、谢家烋公式、比尔鲍曼公式、铁路隧道设计规范计算公式均不适用于富水环境隧道。现场实测支护承受的水压、接触压力均明显不对称,拱脚和墙脚成为关键安全控制部位,建议加强该部位参数和非对称支护设计。富水软岩环境下隧道钢拱架架设后能够立即承载,是控制富水软岩隧道稳定性的有效手段。

Construction of large section tunnel in water-rich soft rock environment has high risks;the safety along with the load acting on support structures has been a key scientific problem in academic and engineering fields.Based on Shibanshan tunnel of Shitai passenger dedicated line,the distribution characteristics of ground pressure,mechanical behavior of steel ribs,contact pressure and water pressure are analyzed by field test and three-dimensional finite element simulation.The results show that the pressure distribution of surrounding rock of tunnel in soft rock stratum with rich water and large cross-section is uneven,and the typical theories like Promojiyfakonov’s theory,Terzaghi’s theory,Xie Jiaxiu’s theory,and Bierbaumer’s theory together with current Chinese Code for Design of Road Tunnel are not suitable for predicting ground load in saturated ground.Field measurements show that the water pressure and contact pressure of the support are obviously asymmetrical,arch foot and wall foot become the key safety control parts,it is suggested that the parameters of this part and the design of asymmetric support should be strengthened.Steel arch can bear load immediately after erection in water-rich soft rock tunnel,and it is an effective method to control the stability of water-rich soft rock tunnel.