The safe thickness of water-barrier rock wall during excavation of karst tunnel

2011 ◽  
Author(s):  
Jinshan Sun ◽  
Guangli Xu ◽  
Jinping Fan ◽  
Lu Zhang
Keyword(s):  
Karst Tunnel ◽  
Rock Wall ◽  
Water Barrier ◽  
Safe Thickness

Study on Safe Thickness of Comparatively Intact Rock Ahead of Karst Tunnel Face

2011 ◽  
Vol 90-93 ◽  
pp. 2456-2459 ◽  
Author(s):  
Jia Qi Guo ◽  
Lian Wei Ren ◽  
Xi Liang Liu
Keyword(s):  
Mechanical Model ◽  
Water Pressure ◽  
Water Inrush ◽  
Intact Rock ◽  
Tensile Fracture ◽  
Karst Tunnel ◽  
Tunnel Face ◽  
Rock Wall ◽  
Safe Thickness ◽  
Tension Strength

Under the effect of water pressure in karst cave before tunnel face, water inrush happens when excavation face enters into the minimal value of safe thickness. Aiming at comparatively intact rock ahead of karst tunnel face, rock wall often appears to be tensile fracture. With some hypotheses, a mechanical model of water inrush for tunnel face instability has been established, furthermore, the analytical expression to calculate safe thickness of rock wall has been given based on the criteria of tension strength through elastical theories. Combined with Maluqing tunnel in Yiwan line, applicability and reliability of formula is discussed.

scholarly journals The Minimum Safe Thickness and Catastrophe Process for Water Inrush of a Karst Tunnel Face with Multi Fractures

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 686 ◽  
Author(s):  
Jiaqi Guo ◽  
Yuan Qian ◽  
Jianxun Chen ◽  
Fan Chen
Keyword(s):  
Rock Mass ◽  
Water Pressure ◽  
Water Inrush ◽  
Karst Water ◽  
Karst Tunnel ◽  
Tunnel Face ◽  
Measuring Point ◽  
Karst Cavity ◽  
Study Results ◽  
Safe Thickness

Water inrush of tunnel face is one of the most common geological disasters during tunnel construction in China. Aiming at the rock mass with multi fractures in water-resistant strata ahead of karst tunnel, the compressive-shear cracking property is analyzed by fracture mechanics theory and the change law of rock bridge shear strength with branch crack propagated length under karst water pressure and geo-stress is studied according to Mohr-Coulomb strength criterion. Moreover, the critical water pressure of water-resistant strata with multi fractures under tension-shear failure is deduced. The safe thickness of water-resistant strata with multi fractures ahead of karst tunnel is established based on two band theory and critical water pressure, and the influence of karst water pressure, initial crack length, crack spacing, array pitch of cracks, lateral pressure coefficient and the angle between the crack and the maximum principal stress on the minimum safe thickness of water-resistant strata are discussed. A 3 Dimension Distinct Element Code (3DEC) considering the fluid-solid coupling effect and structural characteristics of rock mass is adopted to study the catastrophe process and the influence of karst cavity scale on displacement and seepage field in water-resistant rock mass ahead of tunnel in the process of sequential excavation. The numerical simulation results show that: The transition from the single effect of unloading on the extrusion displacement of karst tunnel face to combined action of unloading and karst water pressure occurs with the tunnel face advance; The displacement at each measuring point in water-resistant strata continues to increase in the process of tunnel excavation; The extrusion displacement and water flow velocity in tunnel face suddenly increase when the water inrush pathway is about to form; With the increase of karst cavity size, the minimum thickness of water-resistant strata, the displacement of measuring point and pore pressure of crack increase. The study results provide a reference for early warning and prevention of water inrush in karst tunnel face.

Model Validations and Predictions for Water Barrier Defense

1998 ◽  
Author(s):  
William G. Szymczak ◽  
Charles E. Higdon
Keyword(s):  
Water Barrier

THE GUSHING WATER HAZARD ASSESSMENT OF KARST TUNNEL IN THE PLATEAU OF EASTERN YUNNAN，CHINA

2018 ◽  
Author(s):  
Mo Xu ◽  
◽  
Yanna Yang ◽  
Yanna Yang ◽  
Qiang Zhang ◽  
...  
Keyword(s):  
Hazard Assessment ◽  
Karst Tunnel ◽  
Water Hazard

scholarly journals Radial Water Barrier in Submarine Cables, Current Solutions and Innovative Development Directions

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2761
Author(s):  
Leszek Resner ◽  
Sandra Paszkiewicz
Keyword(s):  
Moisture Absorption ◽  
Wind Farms ◽  
High Moisture ◽  
Water Barrier ◽  
Operational Factors ◽  
New Challenges ◽  
Submarine Cables ◽  
Further Development ◽  
Lead Aluminium

With wind turbines increasing in size, installed at greater distances from the mainland, and greater depths, submarine cables are facing new challenges. Materials and technologies used so far for the production of submarine cables with lead, aluminium, or copper sheaths make them unsuitable or even obsolete for modern solutions such as floating wind farms. The article discusses types of submarine cables, their construction, working conditions, and operational factors, with emphasis placed on the role of the radial water barrier. The focus has been placed on dry and semi-dry designs. The article is also devoted to a discussion regarding directions of further development, possible materials, and constructions that may appear in the future. Current research and results regarding the use of multi-layer coatings with the use of thermoplastic block copolymers for the layer with high moisture absorption are also presented.

Sign in / Sign up

Export Citation Format

Share Document