Evaluation of rock-mass permeability tensor and prediction of tunnel inflows by means of geostructural surveys and finite element seepage analysis
Evaluation of rock-mass permeability tensor and prediction of tunnel inflows by means of geostructural surveys and finite element seepage analysis
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DOI：
10.1016/j.enggeo.2008.05.002
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发表时间：
2008-10-17
影响因子：
7.4
通讯作者：
Boerio, V.
中科院分区：
文献类型：
--
作者：
Coli, N.;Pranzini, G.;Boerio, V.
本文提出了一种新的评价复杂裂隙岩体导水系数和隧道涌水量的实用技术方法。本研究旨在评估从Firenze诺德门至Barberino di Mugello（托斯卡纳）的新公路项目沿线规划的沿着隧道的水流。通过野外调查、地质和水文地质研究，以岩体详细而全面的地质构造特征为基础，从野外调查的不连续性出发，采用Kiraly方程计算了条形张量下的渗透率（K），并引入了有效水力裂隙开度（e）。使用专门为此目的开发的自动化软件脚本计算每个地质结构测量站的杆下张量（K）的主方向。还收集并分析了来自吕荣试验的可用K数据，由于其结构性，结果不能完全代表岩体（水力）可变性。为了评估计划在地下水位下开挖的隧道中的水流（共8个），对38个横向于隧道路径（α平面）的代表性地质剖面进行了有限元渗流分析。每个剖面都是最近的、地质学上最相容的地质构造站。通过三角变换将杆张量下（K）的主方向投影到α平面上。然后，对长期稳定状态以及隧道开挖后立即进行的初始状态进行了评价。根据开挖上方水头的变化，将每个单元段计算的流入量值扩展到隧道的地质均匀长度，然后将每个隧道的整个长度相加。与其他流入评价方法相比，与FE渗流分析得到的流入值。(C)2008 Elsevier B.V.保留所有权利。
In this paper, a new practical technical approach for the evaluation of hydraulic conductivity and tunnel water inflow in complex fractured rock masses is presented. This study was performed in order to evaluate water flow into tunnels planned along the new highway project from Firenze Nord gate to Barberino di Mugello (Tuscany). The results are based on detailed and comprehensive geostructural characterization of rock masses, by means of field surveys, geological and hydrogeotogical studies.Starting from discontinuities properties surveyed in the field, the permeability (K) under bar tensor was calculated using the Kiraly equation, integrated with the introduction of the effective hydraulic opening of fissures (e). Principal directions of tensor (K) under bar were calculated for each geostructural survey station using an automated software script especially developed for this purpose.Available K data from Lugeon tests were also collected and analyzed with results that do not fully represent the rock mass due to its structural (hydraulic) variability.In order to evaluate water flow into tunnels planned for excavation under the water table (for a total number of eight), a finite elements seepage analysis was performed on 38 representative geological sections transverse to tunnel paths (alpha-planes). Each section referred to the nearest and geologically most compatible geostructural station.Principal directions of (K) under bar tensors were projected on the alpha-planes by means of trigonometric transformations. Unitary water inflows were then evaluated for long-term steady-state, as well as for initial state immediately after tunnel excavation. Inflow values calculated for each unitary section were extended to geologically homogeneous lengths of the tunnel, according to the variability of the water head above excavation, and then summed up for the whole length of each tunnel. Inflow values obtained with FE seepage analysis were also compared to other inflow evaluation methods. (C) 2008 Elsevier B.V. All rights reserved.