基于流固耦合的富水软岩地层隧道排水方案研究

为研究富水软岩隧道最优排水方案,以甘肃省道S304线关山隧道为研究对象,基于流固耦合分析理论,建立了应力场和渗流场作用下的隧道开挖模型。借助SoilWorks有限元软件对隧道全排水、全封堵及堵水限排三种施工方案进行了模拟,并对孔隙水压力及水位线、位移场及应力场、围岩塑性区的分布规律进行了研究。结果表明:富水软岩隧道开挖时,采用堵水限排方案可以有效减小对地下水位的影响,经济效益显著;三种施工方案中,堵水限排方案隧道的拱顶沉降、隧底隆起以及地表下沉量最小,但围岩的应力最大,仰拱最大拉应力为全排水方案的2.2倍;全排水方案与全封堵方案围岩塑性区主要产生在仰拱,堵水限排方案围岩塑性区主要产生在边墙两侧,塑性区的范围较小。研究结果可为富水软岩地层同类工程排水方案的确定提供借鉴。

Study on the drainage scheme of water2rich soft rock tunnel based on solid2fluid coupling

In or der t o determine the best drainage scheme o f wat er2rich soft rock tunnel, the excavation models of the Guanshantunnel in Gansu Pro vince wer e established under str ess and seepag e fields based o n t he co upling theor y of fluid and solid. T hecomplete dr ainage scheme, no n2dra inag e scheme, and co nt rolled dr ainage scheme w ere ana lyzed using the finite element analy sisso ftwa re SoilWo rks. The distributio n character istics of pore w ater pressure and water lev el, t unnel displacement and stress, andplastic zo ne o f sur rounding ro ck w ere studied. T he results showed that the co nt ro lled drainag e scheme can reduce the effect tounder gr ound w ater during the tunnel excavat ion; fo r the contro lled dr ainage scheme, the amo unts o f cr ow n set tlement, inv ert up2lift, and g round settlement are the smallest w hile the surr ounding r ock str ess is the larg est, and t he inver t max imum tensio nst ress fo r the contro lled dr ainage scheme is 2. 2 times of that for the complete dr ainage scheme; and the r ock plastic zone ismainly distributed in the invert area for the complete drainag e scheme and no n2drainag e scheme, and in the side w all fo r the con2tr olled dr ainage scheme. The results can pro vide refer ence for the select ion of drainag e scheme of w ater2r ich so ft ro ck tunnel.