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Open accessJournal ArticleDOI: 10.1080/1064119X.2019.1703126

Development and assessment of a water pressure reduction system for lining invert of underwater tunnels

04 Mar 2021-Marine Georesources & Geotechnology (Informa UK Limited)-Vol. 39, Iss: 3, pp 365-371
Abstract: To efficiently reduce the secondary lining external water pressure on underwater tunnels, the feasibility of a novel bottom-up drainage and water pressure reduction system for reducing has been val...

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Topics: Underwater (52%)

5 results found

Journal ArticleDOI: 10.1016/J.TUST.2020.103658
Fei Ye1, Nan Qin1, Xing Liang1, Aohui Ouyang1  +2 moreInstitutions (1)
Abstract: The number and length of highways in China far exceed those in other countries. Therefore, to better understand the defects that have occurred in Chinese highways that are currently in service, we collected data on the defects in 90 such tunnels. Using these data, we conducted a systematic study on the causes of such defects. Based on the characteristics thus obtained, the defects could be divided into seven categories: structural deformation, structural damage, material deterioration, water leakage, frost damage, construction defects, and others (accessory facility defects). The results reveal that lining cracks and water leakage are the most common defects in the highway tunnels of China. These tunnel defects can be categorized based on their risk, correlations, visibility, regional characteristics, and progressive nature. Human activities are the primary cause of highway tunnel defects. The treatment measures for such tunnel defects in China can be categorized as additional, repair, and replacement measures; these measures are selected based on actual requirements of addressing the defects. Lastly, corresponding preventive measures and disposal procedures are established based on the abovementioned analyses. The results of this study are expected to serve as a reference and provide significant guidance for the prevention and treatment of road tunnel defects.

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7 Citations

Open accessJournal ArticleDOI: 10.1155/2020/1686753
Weiwei Liu1, Jianxun Chen1, Yanbin Luo1, Zhou Shi1  +2 moreInstitutions (1)
Abstract: Environmental pollution and energy conservation in urban tunnels have become important issues that affect the scientific design and sustainable development of urban tunnels. The carbon monoxide (CO) concentration in urban road tunnels is regarded as a direct reflection and a useful tracer of the intensity of anthropogenic transportation activities. Previous studies in recent years have paid more attention to pollutant emission factors, but less to the calculation parameters of ventilation design for tunnels. This paper aims to study a reasonable annual reduction rate of CO base emission factors. Therefore, a detailed field measurement was carried out in the four typical urban road tunnels, Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel in Shenzhen, China, from March 29 to September 16, 2014. Measurement results showed that the traffic flow of the four urban tunnels had been approaching the design value, or even beyond the limit. The average daily air velocities in the four tunnels were all within 5 m/s, whereas the maximum air velocity had exceeded the limit of 10 m/s. The CO concentrations in Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel were 17 ppm, 7 ppm, 39 ppm, and 8 ppm, respectively. Moreover, it was found that the average CO emission factors of Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel were 1.075 g/(km·veh), 1.245 g/(km·veh), 4.154 g/(km·veh), and 1.739 g/(km·veh), respectively. Based on the statistical data, the CO emission factors of mixed traffic and passenger cars decrease by an average of 16.4% and 33.3%, respectively, per year through the regression method and by an average of 17.4% and 29.0%, respectively, per year through the extremum method. Finally, when considering the safety factor of 20%, it is more reasonable for the CO base emission to adopt 4% as an annual reduction rate for ventilation design in urban tunnels.

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Topics: Environmental pollution (52%)

3 Citations

Journal ArticleDOI: 10.1007/S10064-020-01865-0
Jinxi Dou1, Guijin Zhang1, Mengxia Zhou, Zhilin Wang  +5 moreInstitutions (3)
Abstract: The Baihetan super-high arch dam is constructed under complicated geological conditions, including large-scale columnar jointed basalt (CJB) with closely spaced joints and multiple interlayer and intralayer shear belts at the lower part of dam base, which may increase a risk of seepage in adjacent dam foundations. Therefore, curtain grouting is used to reduce the permeability of dam foundations. Lugeon and grouting field tests and geological exploration were carried out to investigate curtain grouting characteristics of the dam foundation. The findings were as follows: (1) the permeability coefficient of the first type of CJB and breccia lava without unloading is 2 × 10−5 ~ 5 × 10−5 cm/s; that of the second type of CJB without unloading is 2.5 × 10−5 ~ 5 × 10−5 cm/s; and that of the unloaded third type of massive basalt is 1 × 10−5 ~ 3 × 10−5 cm/s. (2) The rock core shows that the slurry caused repeated splitting of the rock mass and widened the cracks of the rock mass, which resulted in plastic deformation of the rock mass. The P ~ Q curve of the five-point Lugeon test shows that the curve shape is turbulent and that the maximum Lugeon value appears at the highest pressure. (3) The phenomenon of low-permeability conditions with a large grout take can be frequently observed. The proportion of the hole stages with a water permeability less than 1 LU and grout take greater than 50 kg/m ranges from 12.5 to 37.5%. The proportion of holes with permeability greater than 10 Lu and grout take greater than 50 kg/m is 0 to 12.5%. The findings from this case study can provide a reference for engineering construction.

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Topics: Arch dam (61%), Grout (55%), Rock mass classification (53%)

2 Citations

Journal ArticleDOI: 10.1016/J.TUST.2021.103989
Yiguo Xue1, Binghua Zhou1, Shucai Li1, Daohong Qiu1  +2 moreInstitutions (1)
Abstract: It is difficult to comprehend the deformation rule and mechanical characteristics in the construction process of subsea tunnel crossing weathered trough owing to the complex tunnel structure and unfavorable geological conditions. In this study, a geomechanical model test and a numerical model system for the excavation of subsea tunnel were developed based on Haicang Subsea Tunnel to investigate the characteristics of the tunnel displacement, stress, and seepage. After subsea tunnel excavation, the displacement, stress, and hydraulic pressure distribution of surrounding rocks were similar, with the release of stress and lower hydraulic pressure often accompanied with the growth of its displacement. Generally, multiple-physical monitoring information was interactional. In addition, the influence of seawater on the weathering trough was mainly concentrated in an area approximately twice the diameter of the hole, and the influence of water on the vault was greater than that of the sidewall. These results could serve as reference for the construction of subsea tunnel crossings and warning mechanisms of weathered trough.

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Topics: Subsea (55%), Trough (geology) (51%)

1 Citations

Journal ArticleDOI: 10.1080/1064119X.2021.1961954
Abstract: For a subsea tunnel, the changeable high water pressure is of great significance in the soil-water-tunnel interaction. In this study, a series of parametric studies were conducted to investigate th...

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Topics: Pore water pressure (58%), Subsea (54%), Lateral earth pressure (53%) ... show more

24 results found

Journal ArticleDOI: 10.1016/J.APPLTHERMALENG.2018.05.074
Lifeng Fan1, Jingwei Gao1, Zhijun Wu2, Sheng-Qi Yang  +1 moreInstitutions (3)
Abstract: The thermal effects on micro-properties of granite were experimentally studied. The volumetric porosity was observed by the X-ray Computed Tomography (CT) technique and three-dimensional (3D) image reconstruction. Two indexes (heterogeneity coefficient and anisotropy coefficient) were proposed to describe the micro-properties of granite. The thermal effects on these two indexes were discussed. The results shows that micro-porosity increases as temperature increases between 400 °C and 800 °C. It is slightly influenced by temperature beyond this range. Both of the heterogeneity and anisotropy of thermal treated granite increase to their maximums as temperature increases to 500 °C, than decrease to constants as temperature further increases. The heterogeneity and anisotropy of granite are mainly dominated by the initial cracks below 200 °C. The thermal induced cracks are mainly in the regions of lower density mineral grains below 400 °C. Boundary cracks and trans-granular cracks generate significantly above 500 °C.

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Topics: Anisotropy (52%)

101 Citations

Journal ArticleDOI: 10.1016/J.TUST.2008.10.006
Abstract: This study deals with the effect of drainage conditions on porewater pressure distributions and lining stresses in drained tunnels. Firstly, simple closed-form analytical solutions for the steady-state porewater pressure are re-derived within a common theoretical framework for two different boundary conditions (one for zero water pressure and the other for a constant total head) along the tunnel circumference by using the conformal mapping technique. The difference in porewater pressure distributions among the analytical solutions is investigated. The numerical simulation of a drained circular tunnel under the steady-state groundwater flow condition is made to investigate the effect of porewater pressure distributions on lining stresses. Secondly, the case study of the planned South Blue Line Extension subway tunnel under the steady-state groundwater flow condition is performed for four different drainage conditions (sealed, fully-drained with zero water pressure or a constant total head, and invert only-drained) along the tunnel circumference. The effects of different drainage conditions on porewater pressure distributions, flow nets, and lining stresses are investigated.

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Topics: Water flow (54%)

59 Citations

Journal ArticleDOI: 10.1007/S12517-017-3297-1
Junling Qiu1, Yongli Xie1, Haobo Fan1, Zhichao Wang1  +1 moreInstitutions (1)
Abstract: A great concern for the safety of large cross-section tunnels, which are being or to be built in the loess strata of China, is attracted. Generally, loess is a multi-phase porous medium and develops complex stress and strain variation while executing a tunnel project. Another problem is that the soil surrounding both tunnel arches is subjected to a complex loading due to the double excavation. To obtain an in-depth knowledge of the mechanism of tunnel deformation induced by the twin-tunnelling, we conducted comprehensive centrifuge tests, which can simulate and reproduce strictly the action process of twin-tunnelling. Through the model tests, the response of twin-tunnelling on loess stratum deformation was obtained. The investigations showed that with the increase of tunnel spacing, the stratum deformation distribution near the vault changes from a single-peak V shape to a double-peak W shape. Additionally, the height of the stratum pressure arch effect increases significantly. The settlement of the preceding tunnel is slightly larger than that of the latter tunnel, and the twin-tunnelling effect gradually decreases with the increase of tunnel spacing. Through comparative analysis of the different combinations of tunnel spacing and tunnel interval, the interaction between two tunnels with different spacing and interval during tunnelling was investigated, further optimizing the reasonable tunnel spacing and construction steps, as well as providing reference for tunnel route selection in the loess strata.

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48 Citations

Journal ArticleDOI: 10.1016/J.TUST.2007.10.004
Wang Xiuying1, Zhongsheng Tan1, Mengshu Wang1, Mi Zhang1  +1 moreInstitutions (1)
Abstract: To reduce environmental effects due to free tunnel drainage, a controlled drainage scheme is proposed for tunnels under high water level, for which there is no code provision for tunnel design. A suitable structure form is suggested and the distribution of water pressure on tunnel lining is studied by theoretical analysis, indoor test and field measurement. The study indicates that the grouting zone cannot reduce water pressure on lining with complete waterproofing, only when drainage measure is taken can the grouting zone be effective in reducing water pressure on lining. It is also shown that there exists an optimum size for grouting zone, increase of the size of grouting zone may not unlimitedly reduce the water pressure on lining.

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Topics: Drainage (52%), Waterproofing (50%)

45 Citations

Open accessJournal ArticleDOI: 10.1155/2019/8541959
Junling Qiu1, Yiwen Qin1, Jinxing Lai1, Ke Wang  +3 moreInstitutions (2)
11 Feb 2019-Geofluids
Abstract: The reasons, prevention, and control of loess disaster are of great concern in practice. In recent years, Xi’an city, China, has taken the leadership in large-scale construction of subway lines in the loess strata. To study the structural response of the tunnel in loess region under local hydrodynamic environment, an experimental testing in 1g as well as a numerical simulation were performed, in which the achieved results were verified and were found to be in good agreement. Furthermore, the results showed that when the water outlet point is above the lining, the overall stress of the lining is “peanut shell,” as the water pressure of the outlet point decreases, the tensile stress of the top and bottom of the lining increases, while the compressive stress on both sides decreases; the channel form of the flow to the lining changes with the variation of the position of the water outlet point. It is worth mentioning that in the process of water gushing, the closer to the water source, the greater surface subsidence is, and there is a positive correlation between water pressure and surface subsidence. This study is of significant benchmark for the construction, maintenance, and prevention of tunnel in loess strata under the influence of water environment.

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39 Citations

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