深埋TBM隧洞渗流动态演化机制

来源期刊:中南大学学报(自然科学版)2016年第12期

论文作者:苏凯 周亚峰 伍鹤皋

文章页码:4231 - 4240

关键词:TBM隧洞;渗流;孔压;时间效应;二次开发

Key words:TBM tunnel; seepage; pore water pressure; time effect; secondary development

摘    要:针对TBM隧洞动态掘进特征,采用与时间相关的动态边界条件模拟隧洞开挖、管片支护以及豆砾石灌浆等施工过程,结合管片衬砌在高(内、外)水压作用下渗透系数随着充排水过程而不断变化的特点,采用基于立方定理和管片接缝张开度的等效渗透系数来反映结构变形对渗透系数的影响,进而提出管片衬砌的等效耦合模型,并将其在大型有限元软件ABAQUS中进行二次开发得以实现,开展深埋TBM隧洞从施工开挖、管片衬砌支护、充水运行到放空检修全过程周期的仿真模拟分析。研究结果表明:在TBM隧洞动态掘进过程中,洞周孔压先随着开挖掌子面的推进而降低,并在衬砌支护后有所回升,在距离隧洞5倍洞径范围内孔压变化剧烈,开挖影响范围在25倍洞径范围左右;在考虑管片衬砌渗透系数随充水、排水过程的逐渐变化特性后,隧洞渗流场体现了明显的动态变化特征,在充水和排水过程中衬砌外孔压均呈现先减小后增大的规律。

Abstract: Given the dynamic tunnelling characteristics of TBM tunnel, the construction process of tunnel excavation, segments support and pea gravel grouting was simulated under the dynamic hydraulic boundary condition along with time. Considering that the permeability of segment lining changes with the high internal and external water pressure during the water filling and drainage process, an equivalent permeability based on the cubic law and the opening between lining segments was introduced to reflect the influence of structural deformation on the seepage property of segment lining. Thus an equivalent coupled model was proposed and developed by the secondary development in the finite element software ABAQUS. The simulation analysis of deep-buried TBM tunnel during the whole process of the tunnelling, segment lining support, water filling operation and drainage maintenance period were carried out. The results show that during the dynamic tunnelling process, the pore water pressure around the tunnel decreases with the excavation of the tunnel face firstly, and then increases gradually after the segment lining support. Furthermore, the pore water pressure changes dramatically in the scope of 5 times tunnel diameters, and the range of excavation impact is about 25 times tunnel diameters. After considering the variation of the segment lining permeability along with the water filling and drainage process, the seepage field shows obvious dynamic varying characteristic and the pore water pressure presents the pattern of increasing first and then decreasing.

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