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Treatment Technique of Tunnel Disaster Caused by Groundwater

Author: GeHongLiang
Tutor: GeKeShui
School: Chinese Geology University (Beijing)
Course: Underground construction
Keywords: Groundwater Mountain tunnel Formation Mechanism Disaster Treatment
CLC: U457.5
Type: Master's thesis
Year: 2011
Downloads: 193
Quote: 1
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Abstract

Tunnel due to the infiltration of surface water, groundwater seepage, karst hydrocephalus likely to cause the side of the tunnel excavation Yang slope slump depletion of shallow groundwater, surface subsidence, water inrush, landslides, surrounding rock deformation intrude limit, lining concrete corrosion Tunnel disaster. Serious consequences of these disasters, great harm to delay the construction period, reduce economic efficiency, resulting in adverse social impact, it will result in serious loss of life and property. Therefore, it is necessary to conduct a careful analysis of the relationship between groundwater and tunnel common disasters, and propose effective prevention and control measures to achieve during the tunnel construction and operation of disaster prevention, mitigation, governance disaster of purpose. This paper combines the project on the basis of limestone, sandstone and mudstone area long highway tunnel inflow prediction and Treatment Research to participate in the on-site data compilation, the typical Chongqing Fu Feng Shi Expressway fruit trees tunnel, Jianfengling tunnel and cedar floor tunnel background, theoretical results from domestic and foreign researchers, for different geological characteristics of the tunnel entrance section with shallow and deep burial section analysis of the groundwater to the different stages of the tunnel construction is prone to disasters induced effect, asked the Treatment of a system under different stages of the program, used to guide the design and construction. Specific summarized as follows: a lower water table unsaturated Yang slope, rainfall infiltration edge Yang a transient increase in the water pressure of the unsaturated zone above the groundwater level in the slope, the matric suction decreases, reducing the unsaturated soil shear strength; same time, in some regions more than stabilize water tables may appear transient saturated zone, resulting in transient additional water load. In fact, this transient groundwater sub-movement and transient additional water load often become Unsaturated side slope controlling factor in the instability of the rainy season. Tunnel gushing due to the excavation of the tunnel, the man-made destruction in which the original water in fractured rock groundwater seepage field and ground stress field of dynamic equilibrium system. Water in fractured rock in order to maintain their own stability, groundwater seepage movement, with the coupling between the water in fractured rock in groundwater seepage field and ground stress field, so that the stored energy from the new groundwater bodies seepage paths to fluid The high-speed transport in the form of instant release. With rock pore water pressure increased, the surrounding rock plastic damage range to expand in a non-stable equilibrium state when the pore water pressure in the tunnel surrounding rock close to the critical water pressure tunnel surrounding rock; groundwater seepage on the soil skeleton etc. the effectiveness of the role will affect the strength of the foundation soil; addition coupled with insufficient water swelling clay, and support parameters superimposed, causing the surrounding rock deformation value may exceed the design reserved. 4. Groundwater as an important geological forces, and the rock mass between interaction, on the one hand, to change the physical, chemical and mechanical properties of the rock mass; the other hand, changing the groundwater itself the physical and mechanical properties and chemical composition . Movement of groundwater and rock mass produce three kinds of role that the role of the physical, chemical and mechanical, these effects often tunnel collapse plays a decisive impact. 5 of tunnel entrance strata strong weathering, since the stability difference between the geological conditions; human brush slope, destruction of the natural balance of the construction method; combined with rainwater infiltration, deterioration of the cover layer, activate a potential slip crack surface, by effectively lead row surface water, prevent stormwater infiltration by anti-slide pile of bracing, from the fundamental solution to the hole upward Slope slump. 6. Tunnel section with shallow coverage thin arch initial deformation and relaxation scope excavation caused by the surrounding rock is easy to extend to the surface, the stress field and seepage field by rain and coordinate depth than self and other characteristics, by increasing the bearing capacity of foundation, consolidation of surrounding rock, and measures to improve the support parameters up water grouting can effectively prevent the occurrence of surface subsidence, water gushing disasters. Tunnel buried deep segment unknown adverse geological more frequent changes in the level of surrounding rock, once the disaster personnel mechanical greater impact fracture water strengthening the surrounding rock, facilities for closure by radial grouting the temporary invert retaining arch shorten construction spacing between the two the lining with early lining encryption ahead anchor and construction short pipe roof measures paragraph buried deep large deformation, the effects of disasters such as landslides, water gushing significant. The innovation of this paper is to summarize Fu Feng Shi Expressway project is the construction of three tunnels, and into the hole for the tunnel construction section with shallow, buried deep segment the different characteristics of groundwater disasters, the development and evolution of its seepage field system numerical simulation and theoretical analysis, and field test results caused by groundwater in a system for tunnel construction to the various stages of geological disasters prevention measures, and thus of the the Fu Feng Stone project tunnels and similar items tunnel construction provides guidance.

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CLC: > Transportation > Road transport > Tunnel project > Tunnel maintenance, repair,and technological innovation > Natural disasters and measures
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