scholarly journals Dynamic Change Characteristics of Groundwater Affected by Super-Long Tunnel Construction in the Western Mountainous Area of China

2019 ◽  
Vol 11 (8) ◽  
pp. 2329
Author(s):  
Zhiqiang Zhang ◽  
Peng Xu ◽  
Heng Zhang ◽  
Kangjian Zhang
Keyword(s):  
Fault Zone ◽  
Dynamic Change ◽  
Water Inrush ◽  
Water Inflow ◽  
Economic Losses ◽  
Tunnel Construction ◽  
In Situ Observation ◽  
Mountainous Area ◽  
Linear Cavity ◽  
Change Characteristics

The problem of groundwater is very prominent in super-long tunnel construction, which brings serious potential safety hazards and economic losses to the project. The knowledge of dynamic change characteristics of groundwater and prediction of water inflow is the key to ensure rational design and safe construction in super-long tunnel. In this paper, numerical simulation and in situ observation are conducted to investigate dynamic change characteristics of groundwater and the prediction of water inflow based on the Daxiangling tunnel in Sichuan Province of China. The results show that the numerical model established with detailed geological data and validated with field monitoring data can effectively analyze dynamic change characteristics of groundwater, as well as predict water inflow. The initial state of groundwater is steady when the tunnel is unexcavated. Tunnel excavation has a significant influence on the distribution of groundwater. The flow direction of groundwater will change, and the contour lines of groundwater will be intensive at the tunnel face. These changes will be more obvious and dramatic when the tunnel is excavated into the fault zone, which is a signal that the water inrush is more likely to occur in the fault zone because of a lot of joints and fractures. A connected linear cavity is formed with tunnel holing-through and groundwater begins to flow vertically downwards to the tunnel. As far as the prediction of water inflow is concerned, the numerical method can more precisely calculate the value of water inflow with less than 15 percent relative error compared with the groundwater dynamics method.

An Innovation Simulation Method for Flow State Evolution Laws of Water Inflow and Inrush in Course of Tunnel Excavation (Part II: Applications)

2011 ◽  
Vol 261-263 ◽  
pp. 1104-1108 ◽  
Author(s):  
Zhen Hao Xu ◽  
Shu Cai Li ◽  
Li Ping Li ◽  
Shao Shuai Shi
Keyword(s):  
Water Flow ◽  
Water Pressure ◽  
Water Inrush ◽  
Water Inflow ◽  
Economic Losses ◽  
Flow State ◽  
Tunnel Excavation ◽  
State Evolution ◽  
Evolution Laws ◽  
Karst Conduit

In order to avoid heavy casualties and economic losses, and to get an insight into flow state evolution laws of water inflow and inrush in course of tunnel excavation, simulations were done with COMSOL Multiphysics. By coupling and linking different kinds of sub domain governing equations with boundary conditions and possibly initial conditions, three kinds of water flow state, Darcy’s law for water flow in the limestone aquifer, Brinkman equations for fast fluid in the karst conduit; and incompressible Navier-Stokes equations for freely moving of water in the excavated tunnel, are interacted and coupled with each other. Water pressure and velocity were studied and analyzed in course of tunnel excavation. It is proved that there will be no disastrous water inrush when the seepage deformation of the karst conduit is small, and that it is of vital importance to protect and support the clastic medium of karst conduit, and to strictly guard against any change of the permeability of the karst fillings.

scholarly journals Water Inrush Analysis of the Longmen Mountain Tunnel Based on a 3D Simulation of the Discrete Fracture Network

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Ziming Xiong ◽  
Mingyang Wang ◽  
ShaoShuai Shi ◽  
YuanPu Xia ◽  
Hao Lu ◽  
...  
Keyword(s):  
Water Inrush ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Water Inflow ◽  
Tunnel Construction ◽  
Construction Technology ◽  
Mountain Area ◽  
Groundwater Dynamics ◽  
Discrete Fracture ◽  
Mountain Tunnel

AbstractThe construction of tunnels and underground engineering in China has developed rapidly in recent years in both the number and the length of tunnels. However, with the development of tunnel construction technology, risk assessment of the tunnels has become increasingly important. Water inrush is one of the most important causes of engineering accidents worldwide, resulting in considerable economic and environmental losses. Accordingly, water inrush prediction is important for ensuring the safety of tunnel construction. Therefore, in this study, we constructed a three-dimensional discrete network fracture model using the Monte Carlo method first with the basic data from the engineering geological map of the Longmen Mountain area, the location of the Longmen Mountain tunnel. Subsequently, we transformed the discrete fracture networks into a pipe network model. Next, the DEM of the study area was analysed and a submerged analysis was conducted to determine the water storage area. Finally, we attempted to predict the water inrush along the Longmen Mountain tunnel based on the Darcy flow equation. Based on the contrast of water inrush between the proposed approach, groundwater dynamics and precipitation infiltration method, we conclude the following: the water inflow determined using the groundwater dynamics simulation results are basically consistent with those in the D2K91+020 to D2K110+150 mileage. Specifically, in the D2K91+020 to D2K94+060, D2K96+440 to D2K98+100 and other sections of the tunnel, the simulated and measured results are in close agreement and show that this method is effective. In general, we can predict the water inflow in the area of the Longmen Mountain tunnel based on the existing fracture joint parameters and the hydrogeological data of the Longmen Mountain area, providing a water inrush simulation and guiding the tunnel excavation and construction stages.

scholarly journals Analysis of Tunnel Water Inrush Considering the Influence of Surrounding Rock Permeability Coefficient by Excavation Disturbance and Ground Stress

2021 ◽  
Vol 11 (8) ◽  
pp. 3645
Author(s):  
Helin Fu ◽  
Pengtao An ◽  
Long Chen ◽  
Guowen Cheng ◽  
Jie Li ◽  
...  
Keyword(s):  
Permeability Coefficient ◽  
Water Pressure ◽  
Water Inrush ◽  
Surrounding Rock ◽  
Water Inflow ◽  
Calculation Error ◽  
External Water Pressure ◽  
Ground Stress ◽  
External Water ◽  
Inflow Prediction

Affected by the coupling of excavation disturbance and ground stress, the heterogeneity of surrounding rock is very common. Presently, treating the permeability coefficient as a fixed value will reduce the prediction accuracy of the water inflow and the external water pressure of the structure, leading to distortion of the prediction results. Aiming at this problem, this paper calculates and analyzes tunnel water inflow when considering the heterogeneity of permeability coefficient of surrounding rock using a theoretical analysis method, and compares with field data, and verifies the rationality of the formula. The research shows that, when the influence of excavation disturbance and ground stress on the permeability coefficient of surrounding rock is ignored, the calculated value of the external water force of the tunnel structure is too small, and the durability and stability of the tunnel are reduced, which is detrimental to the safety of the structure. Considering the heterogeneity of surrounding rock, the calculation error of water inflow can be reduced from 27.3% to 13.2%, which improves the accuracy of water inflow prediction to a certain extent.

Water-Inrush Mechanism while Fault Zone Secondary Activated in Mining

2012 ◽  
Vol 524-527 ◽  
pp. 799-802
Author(s):  
Shi Guo Sun ◽  
Shao Jie Feng ◽  
Jia Hao Lei
Keyword(s):  
Fault Zone ◽  
Fracture Zone ◽  
Rock Fracture ◽  
Water Inrush ◽  
Mining Area ◽  
Water Conductivity ◽  
Sublevel Caving ◽  
Discontinuous Deformation ◽  
Height Increase ◽  
The Impact

As many different size faults in the fully-mechanized sublevel caving mining area overlying rock, undermine the continuity of rock deformation, and the occurrence of different conditions, the impact properties vary widely. This paper studies the impact of faults on the water inrush with specific examples of project, obtained the discontinuous deformation on both sides of fault zone induce the fault zone secondary activate and result in it’s water transmitting ability dramatic increase; with the mining geometry increases, the water flowing-fracture zone height increase and lead to the water conductivity channel of faults connect with rock fracture zone, so as to constitute water inrush channel and likely to cause water inrush accident, so to explore the influence of fault for underground work safety has important theoretical significance and application value.

scholarly journals Study on Early Warning Method for Water Inrush in Tunnel Based on Fine Risk Evaluation and Hierarchical Advance Forecast

Geosciences ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 392 ◽  
Author(s):  
Sheng Wang ◽  
Shucai Li ◽  
Liping Li ◽  
Shaoshuai Shi ◽  
Zongqing Zhou ◽  
...  
Keyword(s):  
Early Warning ◽  
Risk Evaluation ◽  
Water Inrush ◽  
Entropy Method ◽  
Design Stage ◽  
Tunnel Construction ◽  
Evaluation Theory ◽  
Strongly Nonlinear ◽  
Advantages And Disadvantages ◽  
And Control

Water inrush is one of the most frequent and harmful geological disasters in tunnel construction. In order to effectively prevent and control the occurrence of water inrush, an early warning method based on fine risk evaluation and hierarchical advanced forecast is proposed. Water inrush is a complex dynamic coupling factors system, the relationship between influencing factors and water inrush is strongly nonlinear. Therefore, the efficacy coefficient model, which has the advantages of standardization, conciseness, and freedom from subjective factors, is improved nonlinearly. The fine risk evaluation theory and method based on the improved efficacy coefficient model consisted of two parts: one is static evaluation used in design stage, and the other is dynamic evaluation applied in the construction stage. The index weights are determined scientifically and reasonably by Analytical Hierarchy Process (AHP) and the entropy method. According to the fine risk evaluation results, combined with the advantages and disadvantages of various forecasting methods, a multistep hierarchical detection method of disaster resources for water inrush is proposed to identify the occurrence characteristics and failure level of disaster sources. The theory has been successfully applied to the #3 inclined well of Yuelongmen Tunnel in Cheng-Lan Railway. The evaluation results had good agreement with the actual excavation data, which indicates that the model is of high credibility and feasibility. The method could improve the prediction accuracy of water inrush and explore geometric characteristics and filling of disaster-causing structures. It is of great significance for avoiding water inrush and guiding the rapid and safe tunnel construction.

scholarly journals Direct and Indirect Economic Losses Using Typhoon-Flood Disaster Analysis: An Application to Guangdong Province, China

2020 ◽  
Vol 12 (21) ◽  
pp. 8980
Author(s):  
Zhuoqun Gao ◽  
R. Richard Geddes ◽  
Tao Ma
Keyword(s):  
Computable General Equilibrium ◽  
Economic Impacts ◽  
Cumulative Risk ◽  
Reference Value ◽  
Guangdong Province ◽  
Economic Losses ◽  
Mountainous Area ◽  
Industrial Sectors ◽  
Flood Disasters ◽  
Indirect Economic Losses

Guangdong Province is one of China’s largest and most developed regions. It is home to more than 113 million people and features unique geographical and climatic characteristics. Typhoons that pass through often result in heavy rainfall, which causes flooding. The region’s risk of typhoon and flood disasters, and the resulting indirect economic impacts, have not been fully assessed. The purpose of this paper is to introduce a method for assessing the spatial and temporal cumulative risk of typhoon-induced flood disasters, and the resulting indirect economic impacts, in order to deal with the uncertainty of disasters. We combined an analytic hierarchy process (AHP) and spatial analysis using a geographic information system (GIS) to produce a comprehensive weighted-risk assessment from three different aspects of disaster, vulnerability, and resilience, with 11 indicators. A new method for computing risk based on spatial and temporal cumulative patterns of typhoon-induced flood disasters was introduced. We incorporated those direct impacts into a computable general equilibrium (CGE) model to simulate indirect economic losses in alternative scenarios according to different risk levels. We found that the risk in the coastal area is significantly higher than that in the northern mountainous area. The coastal areas of western Guangdong, Pearl River Delta, and Chaoshan Plain face the greatest risk. Our results indicate that typhoon and flood disasters have negative effects on the real GDP, residents’ income, consumption, and several other macroeconomic indicators. We found differing disaster impacts across industrial sectors, including changes in the output, prices, and flow of labor among industries. Our estimates provide scientific support for environmental planning, spatial planning, and disaster-risk management in this important region. They are also of reference value for the development of disaster management strategies in similar climatic regions around the world.

Temporal-spatial dynamic change characteristics of evapotranspiration in arid region of Northwest China

2017 ◽  
Vol 37 (9) ◽  
Author(s):  
邓兴耀 DENG Xingyao ◽  
刘洋 LIU Yang ◽  
刘志辉 LIU Zhihui ◽  
姚俊强 YAO Junqiang
Keyword(s):  
Arid Region ◽  
Dynamic Change ◽  
Northwest China ◽  
Spatial Dynamic ◽  
Change Characteristics

scholarly journals Land Subsidence Caused by Urban Metro Tunnel Construction

2015 ◽  
Vol 2 ◽  
pp. 29
Author(s):  
Yang Hao
Keyword(s):  
Land Subsidence ◽  
Rapid Development ◽  
Economic Losses ◽  
Tunnel Construction ◽  
Safety Hazards ◽  
Tunnel Excavation ◽  
Excavation Process ◽  
Potential Safety ◽  
Metro Tunnel ◽  
And Control

<p>With the development of urban transportation, city buses are unable to accommodate daily ground transportation for the public in life, work and study; therefore, urban metro gains rapid development. However, metro tunnel construction would initiate land subsidence issues which bring significant potential safety hazards and economic losses. In order to reduce irrelevant economic losses, this paper discusses the land subsidence issues from three perspectives: analysis of land subsidence, land subsidence safety judgment and control and shallow tunnel excavation method in tunnel construction used to control land subsidence. The paper indicates that there are major geotechnical engineering issues encountered during urban metro tunnel excavation process. The individuals in charge of implementation should optimize tunnel construction regulations and ensure all works are implemented scientifically, regularly and orderly in order to reduce the impacts on land subsidence caused by tunnel construction.</p>

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