膨胀岩公路隧道结构设计与施工稳定性分析

Analysis on Design and Construction Stability of Swelling Rock Highway Tunnel

膨胀岩是遇水发生物理及化学反应,引起岩石含水量及岩性发生变化,且体积发生膨胀的一类岩石。为研究公路隧道在膨胀性围岩段的结构稳定性,依托大华岭特长公路隧道,对膨胀岩隧道的膨胀岩等级判别、结构设计和施工稳定性等方面进行了综合分析。通过对隧道施工过程的数值模拟分析,结果表明,结构的薄弱部位为分步开挖的交接处,尽管应力集中现象及围岩塑性区没有影响结构的安全性能,但在结构设计和施工中仍然要注意设置锁脚锚杆,并严格控制钢架接头的质量及喷射混凝土的厚度。如今该隧道已成功运营,进一步说明文中论述的结构设计参数及施工方案是合理的。

There is a physical and chemical reaction of the swelling rock in case with water. As a result,the water content and lithology of the rock will be changed and the rock will be expanded. In order to study the stability of tunnel in swelling rock,the grade identification,structure design and construction stability in swelling rock highway tunnel were analyzed comprehensively for Dahualing Tunnel. Through the numerical simulation,the results show that the weakest structure lies at the juncture of the step excavations. Although the stress concentration phenomenon and the plastic zone in surrounding rock mass would not affect the safety of the structure,the anchor rods should be set during the design and construction. At the same time,the steel arch connection and the thickness of shot concrete should be stringently controlled. Now,the tunnel is open to traffic successfully. This further verifies that the structural design parameters and the construction scheme are all reasonable.