大坳隧道隧址区渗流场与隧道涌水量数值模拟及预测

发布时间：2018-06-02 23:52

本文选题：大坳隧道 + 地下水渗流场　；参考：《成都理工大学》2014年硕士论文

【摘要】：隧道大流量涌水往往会造成比较严重的后果,它不仅影响隧道的正常施工,且会波及隧道建成后的安全运营。大坳隧道隧址区为典型的高山峡谷地貌,区内崇峰叠嶂,河谷深切,峭壁陡立。岩溶区隧道的涌水量预测一直是隧道开挖和运营过程中要解决的难题,准确预测隧道的涌水量对隧道开挖过程中人员及设备安全有极其重要的作用。为了揭示修建大坳隧道对该隧址区地下水环境造成什么影响、以及地下水环境的变化对隧道涌水有何影响,本文主要开展了以下研究工作： (1)对隧址区地质条件与水文地质条件进行调查分析；(2)建立水文地质概念模型；(3)采用数值模拟等方法,建立隧址区地下水渗流三维数值计算模型；(4)设计下列三维数值模拟方案,对该隧址区地下水渗流场进行三维数值计算研究：①天然状态下地下水渗流场模拟,②隧道开挖后完全排水条件下的地下水渗流场模拟,③隧道开挖后完全排水条件下涌水量模拟预测,并采用理论计算方法研究隧道涌水量,通过对比分析数值模拟与理论计算结果,综合得出隧道的涌水量；④隧道完全封堵条件下的地下水渗流场恢复情况模拟。本文取得的主要成果如下： (1)隧址区岩性为灰岩、砂岩为主。隧道进口段上部覆盖砂岩、砂质页岩,为典型的覆盖型岩溶区,出口段为岩溶发育的清虚洞组灰岩的裸露型岩溶区。隧址区内主要强富水岩组为寒武系清虚洞组灰岩,主要中等至弱富水岩组为寒武系下统金顶山组白云质灰岩和砂岩,相对隔水层为寒武系下统金顶山组砂质页岩。 (2)采用电阻率法,探讨了岩土渗透性与岩体完整性特征,隧道在垂直和水平方向电阻率有很大差异,特别是水平方向,隧道进口段电阻率较高,说明进口段岩性较完整,孔隙度较小,富水性较弱；隧道出口段电阻率低,说明出口段岩性破碎,岩溶裂隙发育,富水性强。采用电阻率方法,对隧道的涌水情况作出了定性分析。 (3)分析了隧址区水文地质条件,概化出了与本区水文地质条件相符的水文地质概念模型,确定了隧址区地下水渗流模型边界条件,并进行了模型的时间和空间离散,建立了大坳隧道隧址区天然渗流场的三维数值模型,通过水均衡拟合和观测水位的拟合,证明了三维数值模型的可信度。 (4)隧道完全排水在隧道周围形成与隧道平行的线状降落漏斗,同时在1个水文年内因降水量周期性变化还具有周期性,在夏季降雨量大的时候,出口段降深减小,可能导致出口段涌水量较大。从隧道进出口处的渗流场变化来看,渗流场在隧道出口段的变化比进口段大得多。从排水90天开始,隧道进口处的最大降深基本保持不变,进口处水位最大降深5m左右,原因可能是隧道进口段上覆砂岩及砂质页岩,渗透系数小,且埋深不大,位于地形顺坡处,涌水量不大；隧道中部由于地下水埋深较大,隧道通过地段水位较高,隧道排水对地下水的影响最大；隧道出口段岩溶较发育,渗透系数大,地下水与降雨关系密切,隧道排水对周围地下水渗流场影响范围较广。 (5)封堵90天后,渗流场恢复明显,隧道中部线性降落漏斗开始消失,隧道进口处与天然水位只相差约2m,出口处与天然水位相差约l0m,隧道中部相差约30m；封堵180天,隧道出口段渗流场迅速恢复,而隧道进口段则恢复较缓慢,隧道中部进口段降深约20m。封堵270天后,大部份区域基本恢复到天然状态的80%。封堵1年后,渗流场基本恢复到初始状态。总体来看,隧道出口段渗流场恢复较快,进口段恢复较慢。这是因为隧址区虽处岩溶区,但是进口段属于覆盖型岩溶区,岩溶发育程度不高,地下水循环较弱,难以得到迅速补给,所以进口段渗流场恢复较缓慢。而出口段岩溶发育,地下水循环迅速,渗流场恢复快。 (6)用数值模拟方法,对已分段的大坳隧道进行分段涌水量计算,并用理论计算方法(降雨入渗法、解析法、比拟法等)对隧道涌水量进行了计算,获得大坳隧道进出口分段涌水量的范围值,即：K97+860-K98+420为117.60～205.07m3/d；K98+420-K98+765为674.82～846.08m3/d。研究成果为该隧道的设计与施工提供了依据。
[Abstract]:The large flow of water in the tunnel often causes serious consequences. It not only affects the normal construction of the tunnel, but also affects the safe operation of the tunnel. The tunnel site area of the Da Ao tunnel is a typical mountain and Canyon landform. The peak is high in the area, the valley is deep and the cliff is steep. The prediction of the water inflow of the tunnel in the karst area is always the tunnel excavation and operation. In order to solve the difficult problem in the process, accurately predicting the water gushing quantity of the tunnel is very important for the safety of the personnel and equipment in the process of tunnel excavation.
In order to reveal the influence of the construction of the Da Ao tunnel on the groundwater environment in the tunnel site and the influence of the change of the groundwater environment on the water gushing of the tunnel, the following research work is carried out in this paper.
(1) to investigate and analyze the geological conditions and hydrogeological conditions of the tunnel site; (2) to establish the conceptual model of hydrogeology; (3) to establish a three-dimensional numerical calculation model of groundwater seepage in the tunnel site by means of numerical simulation, and (4) to design the following three-dimensional numerical simulation scheme for the three-dimensional numerical calculation of the groundwater seepage field in the tunnel site: (1) simulation of groundwater seepage field under natural condition, (2) simulation of groundwater seepage field under complete drainage condition after tunnel excavation, (3) simulation and prediction of water inflow under complete drainage condition after tunnel excavation, and the theoretical calculation method is used to study the water inflow of tunnel. Through comparison and analysis of numerical simulation and theoretical calculation, the water gushing of tunnel is synthetically obtained. The simulation of groundwater seepage field recovery under the condition of complete plugging.
The main achievements of this paper are as follows:
(1) the lithology of the tunnel site is limestone and sandstone mainly. The upper part of the tunnel entrance section covers sandstone and sand shale, which is a typical covered karst area. The exit section is the bare karst area of Qingxu cave limestone in karst development. The main strong water rich rock group in the tunnel site is the limestone of the Qingxu cave formation in the Cambrian system, and the main middle to weak rich water rich rock group is the lower Cambrian system. The dolomitic limestone and sandstone of the Jinding mountain group are relatively sandy aquifers of the Jinding formation in the lower Cambrian.
(2) the resistivity method is used to discuss the permeability of rock and rock and the characteristics of rock integrity. The resistivity of tunnel in vertical and horizontal direction is very different, especially in the horizontal direction. The resistivity of the inlet section of the tunnel is high, which indicates that the inlet section is relatively complete, the porosity is small, the water rich is weak, and the resistivity of the tunnel exit section is low, indicating the lithology broken in the exit section. The karst fracture develops and the water is strong. A qualitative analysis is made of the water gushing condition of the tunnel by means of resistivity method.
(3) the hydrogeological conditions of the tunnel site are analyzed, and the hydrogeological conceptual model which is consistent with the hydrogeological conditions in this area is generalized. The boundary conditions of the groundwater seepage model in the tunnel site are determined, and the time and space discretization of the model is carried out. The three-dimensional numerical model of the sky natural seepage flow field in the Great Depression tunnel is established, and the water equilibrium is fitted and fitted by the water balance. Fitting the observed water level proves the credibility of the three-dimensional numerical model.
(4) the tunnel is fully drained around the tunnel to form a linear landing funnel parallel to the tunnel. At the same time, in the 1 hydrological years, the periodic variation of the precipitation is periodic. When the rainfall is large in the summer, the depth of the exit section decreases, which may lead to a large flow of water in the exit section. The variation of the tunnel exit section is much larger than that of the inlet section. From 90 days of drainage, the maximum depth of the inlet of the tunnel remains unchanged, and the maximum depth of the inlet water level is about 5m. The reason may be that the tunnel inlet section is covered with sandstone and sand shale, and the permeability coefficient is small, and the depth is not large. The water inflow is small, and the middle part of the tunnel is located in the middle of the tunnel. The underground water depth is larger, the water level in the tunnel through the tunnel is higher and the tunnel drainage has the greatest influence on the groundwater; the tunnel exit Duan Yanrong is more developed, the permeability coefficient is large, the groundwater is closely related to the rainfall, and the tunnel drainage has a wide influence on the surrounding groundwater seepage field.
(5) after 90 days, the seepage field is restored obviously, the linear landing funnel in the middle of the tunnel begins to disappear, the inlet of the tunnel is only about 2m, the difference about the natural water level is about l0m, the difference about the middle part of the tunnel is about 30m, and the seepage field of the tunnel exit section is quickly restored for 180 days, while the entrance section of the tunnel is slowly restored and the entrance of the tunnel is imported. After 270 days of depth reduction for 270 days, the seepage field is basically restored to the initial state after 1 years of recovery of most of the region to the natural state of 80%. plugging. In general, the seepage field of the tunnel exit section is faster and the entrance section is slower. This is because the tunnel site is located in the karst area, but the entrance section is covered by the karst area and the degree of karst development. Not high, the groundwater circulation is weak, it is difficult to get the rapid recharge, so the seepage field of the inlet section is slowly restored, and the karst development of the exit section, the rapid circulation of the groundwater and the rapid recovery of the seepage field.
(6) the numerical simulation method is used to calculate the water gushing amount of the segmented big depression tunnel, and the water inflow of the tunnel is calculated by the theoretical calculation method (rainfall infiltration method, analytic method, analogy method, etc.). The range of the water inflow of the great deao tunnel is obtained, that is, K97+860-K98+420 is 117.60 to 205.07m3/d, and K98+420-K98+765 is 67. The research results from 4.82 to 846.08m3/d. provide a basis for the design and construction of the tunnel.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U452.11

【参考文献】