基于地震变形控制的隧道地基注浆抗液化加固效果评价

ASSESSMENT OF ANTI-LIQUEFACTION GROUTING REINFORCEMENT EFFECT OF TUNNEL FOUNDATION BASED ON EARTHQUAKE-INDUCED DEFORMATIONS CONTROL

目前理论上主要有两种液化防治思路:一种是限制超孔隙水压力的产生与发展;另一种是减少液化产生的过大变形。目前,基于前一种设计思想的液化处理方法和研究较多,而对基于变形控制的处理方法实施效果的研究则相对有限。从后一种思路出发,基于Biot固结理论,利用循环弹塑性本构模型,通过数值模拟方法,对上海某电厂取排水隧道的地震液化问题进行模拟,建立一种平面应变条件下隧道地震液化变形的数值模拟方法,以评估其注浆预防液化的加固效果。其中重点分析了地震作用下加固前后该隧道地基的位移、加速度、超孔隙水压力等动力反应。结果表明,采用适当的抗液化处理措施可以较好地抑制地基液化变形,这为工程场地抗震设计及液化防治提供了科学依据,对类似工程的可液化场地处理具有良好的借鉴作用。

At present, there are two kinds of theories for anti-liquefaction, i.e. prevention of excess pore water pressure generation and development, and reduction of liquefaction-induced deformations. Up to now, most of researches have paid more attentions to the former, while the latter one has not been fully analyzed. Therefore, focused on the latter theory for anti-liquefaction, by using a cyclic elastoplastic constitutive model, liquefaction analysis of a water intake and outlet tunnel of a power plant in Shanghai is carried out by means of finite element method based on Biot＇s consolidation theory. A numerical simulation method for earthquake-induced liquefaction deformation is proposed under plane strain conditions to assess anti-liquefaction grouting effect. The dynamic responses including displacements, accelerations, and excess pore water pressures of tunnel foundation before and after reinforcement are analyzed. It is proved that the liquefaction deformations of the tunnel foundation can be effectively reduced by the proper anti-liquefaction measures. Some scientific suggestions for aseismic designs of this project are proposed based on the results of numerical simulation, and they can provide good references for liquefiable ground treatment of other similar projects.