Application of Spray-on Waterproofing Membrane in Tunnels

2010 ◽  
Vol 168-170 ◽  
pp. 822-826 ◽  
Author(s):  
Jian Qin Ma
Keyword(s):  
Water Pressure ◽  
Surface Condition ◽  
Underground Structures ◽  
Water Ingress ◽  
Waterproofing Membrane ◽  
Sprayed Membrane ◽  
New System ◽  
Single Shell

Waterproofing is one of the key problems of underground structures. Spray-on waterproofing membrane is a new system in tunnels with single shell linings. The conditions of the application of this system are analyzed in terms of the deformation and surface condition of the first layer of the shotcrete shell, water ingress and water pressure behind the waterproofing membrane. The results show that the applications of a spray-on waterproofing membrane in a tunnel is possible if the deformation of the shotcrete and water pressures behind the sprayed membrane is properly controlled, as well as the ingress water is piped or tightened with practical measures. Proposals of measures to meet the conditions are presented for the application of the spray-on waterproofing membrane in tunnels.

scholarly journals Investigation of Groundwater Withdrawal and Recharge Affecting Underground Structures in the Shanghai Urban Area

2019 ◽  
Vol 11 (24) ◽  
pp. 7162 ◽  
Author(s):  
Yong-Xia Wu ◽  
Tian-Liang Yang ◽  
Pei-Chao Li ◽  
Jin-Xin Lin
Keyword(s):  
Land Subsidence ◽  
Urban Areas ◽  
Water Pressure ◽  
Underground Structure ◽  
Pressure Head ◽  
Groundwater Withdrawal ◽  
Underground Structures ◽  
Groundwater Head ◽  
Increased Risk ◽  
Confined Aquifers

In this paper, the hydrogeological features of Quaternary deposits in Shanghai as well as the characteristics of groundwater withdrawal and recharge in urban areas are investigated. One phreatic aquifer and five confined aquifers (AqI to AqV) are present in Shanghai, and these aquifers are separated by five aquitards. Groundwater withdrawal from confined aquifers has resulted in land subsidence in Shanghai. To control land subsidence, the groundwater withdrawal volume has been decreased, and the groundwater recharge volume has been increased since 1965. Correspondingly, the pressure head in confined aquifers has risen. The groundwater head increases in shallow aquifers may impact underground structures and lead to the following issues: i) an increased risk of water in-rushing hazards caused by confined water pressure during structural excavations and ii) an increased instability risk caused by groundwater buoyancy. Both excavation anti-uprush and underground structure anti-floating are discussed in this paper. Based on the risk possibilities, the anti-uprush of the excavation is divided into six regions, and the structural anti-floating is divided into five regions in urban areas. To avoid geohazards caused by the rise in groundwater head, real-time monitoring of the pressure head in AqII is recommended.

Research of Seepage Influence on the Lateral Water-Earth Pressure in Underground Structures

2013 ◽  
Vol 838-841 ◽  
pp. 1663-1666
Author(s):  
Dai Kui
Keyword(s):  
Force Field ◽  
Pressure Field ◽  
Water Pressure ◽  
Earth Pressure ◽  
Underground Structures ◽  
Seepage Force ◽  
Foundation Pit ◽  
Field Coupling ◽  
Pressure Water ◽  
Supporting Structures

Earth pressure field and hydrostatic water pressure field are usually considered for classical earth pressure theories. Nonconsideration of groundwater seepage field is one of the main reasons why measured values of water-earth pressure on supporting structures are generally very different from those calculated values.Under the action of seepage,seepage force changes soil effective stress and affects soil shear strength.Through calculating the interraction of the hindering force field and seepage force field,a multi-field coupling problem is solved, a new calculation expressions on the foundation pit is presented.Key words : multi-field coupling; seepage ; lateral pressure ; water-earth pressure ; hindering force

scholarly journals Research on Ground Liquefaction and Structural Force Characteristics of Underground Utility Tunnels Under CLC Stratigraphic Model

2021 ◽  
Author(s):  
Tian Tian ◽  
aijun Yao ◽  
Yifei Gong ◽  
Yaozhen Guo
Keyword(s):  
Pore Water Pressure ◽  
Numerical Study ◽  
Water Pressure ◽  
Volumetric Strain ◽  
Sine Wave ◽  
Burial Depth ◽  
Underground Structures ◽  
Underground Engineering ◽  
Stratigraphic Model ◽  
Structure Height

Abstract Damages to underground structures due to liquefaction of the soils caused by cyclic loads such as earthquakes have always been an important issue in geotechnical underground engineering practices. This paper presents a numerical study of the utility tunnels at different burial depths in "Coh-Liq-Coh" horizontally layered liquefiable grounds using the finite-difference program FLAC3D. "Finn-Byrne" cyclic load volumetric strain increment model simulates the fluid-solid coupling of saturated sand and the increase in pore water pressure during vibration. The numerical model was loaded using an acceleration sine wave for dynamic calculations. The numerical results showed that the burial depths have a strong influence on the liquefaction of the soil beneath the utility tunnels and on the forces and deformations of the structures. Under the numerical simulation conditions in this paper, the greater the burial depth, the greater the liquefaction of the soil beneath the structure, the greater the shear stress on the side walls and the smaller the settlement difference between the structure and the surrounding soil. In the numerical simulations in this paper, a reasonable burial depth for utility tunnels was 0.8 to 1.1 times of the structure height.

scholarly journals Reduction of Groundwater Buoyancy on the Basement in Weak-Permeable/Impervious Foundations

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Jikai Zhou ◽  
Chenghuan Lin ◽  
Chen Chen ◽  
Xiyao Zhao
Keyword(s):  
Pore Water ◽  
Groundwater Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Laboratory Model ◽  
Test Results ◽  
Underground Structures ◽  
Significant Difference ◽  
Reduction Coefficient

At present, groundwater buoyancy is directly calculated by Archimedes’ principle for the antifloating design of underground structures. However, this method may not be applicable to weak-permeable/impervious soils, e.g., clayey foundations, because there is a significant difference between the groundwater buoyancy obtained from field measurements and that calculated by Archimedes’ principle. In order to determine whether the method of calculating groundwater buoyancy in weak-permeable/impervious soil layers by Archimedes’ principle is reasonable, this paper investigated the groundwater buoyancy on the basement in such foundations through laboratory model tests. The following factors that may influence the magnitude of groundwater buoyancy were investigated: change of groundwater level, duration of pore water pressure, and buried depth of the basement. In this study, model test results show that the groundwater buoyancy obtained from measurements is evidently lower than that calculated by Archimedes’ principle. Reduction extent can be expressed by a “reduction coefficient,” which can be calculated by a fitting formula. Moreover, experimental groundwater buoyancy increases with the increase in the groundwater level, and it almost does not change with the growth of duration of pore water pressure. Reduction coefficient ranges between 0.25 and 0.52 depending on different buried depths of the basement. In general, experimental groundwater buoyancy decreases with the increase in the buried depth of the basement.

Influence of Soil Consolidation History on Seismic Response of Underground Structure in Layered Liquefiable Ground

2013 ◽  
Vol 639-640 ◽  
pp. 670-677
Author(s):  
Zhi Fan Xia ◽  
Yan Ling Zheng ◽  
Guan Lin Ye
Keyword(s):  
Constitutive Model ◽  
Pore Water ◽  
Yield Surface ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Underground Structure ◽  
Soil Consolidation ◽  
Underground Structures ◽  
Excess Pore Water Pressure ◽  
Excess Pore

It is shown that liquefaction induced uplift is one of the most typical disasters for underground structures in liquefiable zone. Though a lot of researches were conducted to investigate the uplift phenomenon of underground structures in the past years, further studies need to be carried out to discover its mechanism because the seismic responses were correlated with many factors. In the paper, a fully coupled dynamic analysis was performed to investigate the dynamic responses of underground structure in layered saturated ground. The soils were simulated by a cyclic mobility constitutive model, which adopted some important concepts such as stress induced anisotropy, subloading yield surface, and superloading yield surface. It was verified that the constitutive model can perfectly describe the dynamic character of both liquefiable sand and non-liquefiable clay. Simulated results were obtained for excess pore water pressure and deformation of soil deposit and uplift of underground structure. Special emphasis was given to discuss the influence of soil consolidation history on the seismic responses of underground structure. Simulation indicated that with the occurrence of liquefaction, soils at lateral sides of underground structure flowed toward the bottom of the structure, which led to the uplift of structure. Results also showed that the excess pore water pressure ratio of liquefiable soil decreased with the increasing of soil pre-consolidation pressure. Then the liquefied zones diminished, and the uplift of underground structure reduced.

The Uplift Behavior of Large Underground Structures in Liquefied Field

2011 ◽  
Vol 90-93 ◽  
pp. 2112-2118 ◽  
Author(s):  
Xi Wen Zhang ◽  
Xiao Wei Tang ◽  
Qi Shao ◽  
Xu Bai
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Geometrical Nonlinearity ◽  
Soil Layer ◽  
Ground Surface ◽  
Soil Liquefaction ◽  
Underground Structures ◽  
Liquefiable Soil ◽  
The Stability ◽  
Updated Lagrangian

Soil liquefaction due to the earthquake causes serious damages and engineering problems, such as the reduction of the soil strength, large settlement of the ground surface, the flow of liquefied soil and the uplift behavior to the underground structures, and the large deformation induced by the uplift force threatens the stability and safety of the structures. In this paper, a FE-FD coupled method is used in the simulation, the cyclic elasto-plastic constitutive model and the updated lagrangian formulation are applied to deal with the material and geometrical nonlinearity of liquefied soil. The results show that after the earthquake, the exceed pore water pressure will still exist for some time and the structure has an obvious vertical uplift displacement related to the liquefied area and the flow of liquefied soil. The uplift displacement will decrease as the thickness of the upper liquefiable soil layer is reduced. The results can be regarded as a guidance and reference for the design of the large underground structures.

scholarly journals High Water Ingress during TBM Tunnelling under Andheri Kurla Road, Marol Naka, Mumbai, India.

2019 ◽  
Vol 4 (11) ◽  
pp. 70-73
Author(s):  
Vinay Kumar Pandey ◽  
Satya Prakash
Keyword(s):  
Transport System ◽  
Water Body ◽  
Water Pressure ◽  
High Water ◽  
Geophysical Investigation ◽  
Water Ingress ◽  
High Water Pressure ◽  
Grade Iii

For surface space limitations in metro cities, tunnel is the best option worldwide for the development of modern transport system, utilities and other infrastructures. But tunnelling is full of surprises depending on geological and hydrological factors. Underground Mumbai Metro line -03 is also full of surprises. In this paper we are going to discuss the encountered high water pressure during the Up line mining underneath the Andheri – Kurla road & elevated Mumbai Metro line -01 at Marol Naka. Pressure of water was observed to be 4.5 bars to 5 bars, geotechnical instruments showing no settlement but tunnel always filled with muck and progress were affected badly apart from taking precautions during the mining. As per geology, grade III basal and breccia were encountered. Team tried to find out the source/causes of this high water ingress but even after searching various options such as utility damage, recharging with water body, geological & geophysical investigation options, it was unable to conclude the confirm source. It was very astounding that no high water ingress was observed during the down line TBM mining. In this paper, all options have been discussed in details and also suggesting for taking high precautions during construction of cross passage in this area.

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

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