Underwater Tunnel Research Articles

Unges dialektbrug i bygden Sandur på Færøerne

In this article, dialect changes and variation among young schoolchildren in the island of Sandoy in the Faroe Islands are discussed. The fieldwork was made by a group of students at the University of the Faroe Islands in November 2019 under the guidance of this article’s author. The informants are two groups of 10 and 15 year old schoolchildren. By examining the young generation, we can get information about the ‘state of health’ of the dialect. Here three dialectal variables are examined: (i) The variation of definite and indefinite form of words for family members, for instance the dialectal form mamman ‘the mother’ and the Central Faroese form mamma ‘mother’; (ii) Personal and possessive pronouns in 1st and 2nd person plural in oblique case, for instance the dialect form [o:gʊn] ‘us’ and the Central Faroese form [ɔʰk:ʊn] ‘us’; (iii) The pronunciation of short ó with the dialectal variant [ɔ] and the Central Faroese form [œ], for instance [fɔlk] resp. [fœlk] ‘people’.
 The first variable shows clearly a tendency towards dialect change in the young generation: the indefinite forms are much more frequent than the dialect counterpart. The use of the pronouns shows a relatively high degree of variation: the dialect forms are more frequently used by the 10 than the 15 year old pupils. The pronunciation of short ó shows variation to a large extent. Here we see the same pattern as we saw for variable 2: the youngest pupils are more likely to use the dialect¬al form [ɔ] than the older ones. On the other hand, variation is much more common in the group of 15 year old pupils. 
 This study shows both stability and change in the dialect of children in Sandoy: Stability in use of the dialectal forms of the personal and possessive pro¬nouns, and variation and change in the two other variables. In a couple of years an underwater tunnel will connect the island of Sandoy with the central part of the islands. In a future scenario this dialect study opens the possibility for comparative studies of the dialect of Sandoy before and after the opening of the tunnel.

Research on the Construction Scheme of Jiangsu Taihu Intelligent Tunnel Based on Cloud Platform

Taihu underwater tunnel in Jiangsu province is an ultra-long and ultra-wide tunnel, both longer and wider than the Hong Kong-Zhuhai-Macao bridge. It is worth discussing how to guarantee the safety of underwater tunnel, give play to the application of intelligent transportation, make travellers get all-round comfortable service and managers get economical and efficient management. Starting from the cloud platform and taking Taihu tunnel as the background, this paper analyses the status quo of the tunnel at home and abroad, draws lessons from experience, and studies the structure and functions of the construction scheme of Taihu intelligent tunnel from the perspective of “safety, comfort and economy”.

Research on optimization of frozen wall thickness of underwater tunnel based on fluid-solid coupling theory

Research on optimization of frozen wall thickness of underwater tunnel based on fluid-solid coupling theory

Experimental study about the influence of cyclic load on the hydraulic conductivity of clay

The hydraulic conductivity k, one of the most important engineering properties of soft clay, plays a great role during the whole life cycle of underwater tunnel. Therefore, it is necessary to systematically study the responses of k to the dynamic load under the background of the great development of geotechnical engineering in the world. In this study, a series of seepage tests after cyclic loading were conducted on reconstituted kaolin clay using a modified hollow cylinder apparatus. The influence of cyclic load on the permeability characteristics of soft clay was illustrated in two aspects. The cumulative axial deformation of clay induced by cyclic loading resulted in the smaller hydraulic conductivity of the specimens, and also, the dynamic load reconstructed the microstructure of clay and made the number of large pores getting decreased and the small pores increased. There was a positive correlation between the deformation of soil and the change of hydraulic conductivity, but the reconstruction effect was irregular with the frequency of dynamic load. The measured k values got affected at the beginning, this phenomenon appropriately explains the positive correlation between the number of cycles of dynamic load and the change of hydraulic conductivity.

Underwater sound generated by motor vehicle traffic in an underwater tunnel

Underwater acoustic and environmental measurements were made adjacent to the Monitor-Merrimac Memorial Bridge-Tunnel in the James River in Virginia during a field experiment in April 2019. The observed sound field exhibited short time-scale and tidal time-scale variability due to passing marine vessels and tidally driven currents in the estuary; most interestingly, the sound field exhibited variability on a diurnal time scale, closely correlated to the temporal distribution of vehicular traffic in the underwater tunnel. During morning and evening rush-hour traffic periods, the amplitude of the traffic-induced underwater signal exceeded 10 dB at 40 Hz. Additional physics-based modeling and direct observation are required to verify the hypothesis that the signal is associated with the traffic-induced vibration in the tunnel roadbed.

A static risk assessment model for underwater shield tunnel construction

The shield method is widely used in underwater tunnel construction. However, the shield construction process faces many uncertain risk factors that increase the level of safety risk during shield tunnel construction. Therefore, risk assessment has become a necessary task in the early stages of tunnel construction. In this study, a new risk assessment model for underwater shield tunnel construction is proposed that combines a normal cloud model with an entropy weight method. The model contains 20 assessment indexes and gives the range of each index corresponding to different risk levels, which comprehensively reflects the influencing factors of risk. By using a normal cloud model, the fuzziness and randomness of risk assessment data are taken into account effectively, and the reliability of assessment results is increased. Based on an entropy weight method, the rules and characteristics of the evaluation data in the model are considered, and the weight coefficient of the evaluation index is determined to avoid the subjectivity of the expert weight method. The risk assessment model is applied using the Xiangjiang shield tunnel as an example. The results show that the overall construction risk level of the Xiangjiang tunnel is level II, which is consistent with the site risk situation and shows that the model can objectively and accurately evaluate the construction risk level of an underwater shield tunnel.

Experimental and numerical study on underwater noise radiation from an underwater tunnel

The hydro-acoustic noise radiating from underwater tunnels during vehicle passage may be harmful to aquatic fauna, and this is a particular concern for endangered species. Therefore, the effects of underwater noise radiation and propagation on aquatic biodiversity must be investigated. In this study, the dynamic response of the sediment and tunnel structure in the Yangtze River in China was explored by conducting a field test, and the associated noise radiation from the tunnel was recorded and investigated. A three-dimensional numerical model was then developed to simulate the vibration of the tunnel-sediment coupling system induced by random traffic-flow models. Next, a modal acoustic transfer vector-based method was used to predict underwater noise radiation by use of a three-dimensional finite-element acoustic model. Finally, the accuracy of the simulated results was verified by comparison with measurements. The results showed that the noise radiation induced by passing vehicles was approximately 14 dB greater than the background noise, with a main frequency range of 12–25 Hz. The random traffic-flow model had obvious influence of the simulated noise level above 20 Hz. Vehicle-induced underwater noise may thus have a direct effect on fish species that can perceive low-frequency sound pressure. The proposed method can be used for further investigation of methods to reduce the effect of underwater noise on aquatic fauna, especially endangered species.

A measure of control of submerging and surfacing of an Autonomous underwater vehicle for exploring underwater of rivers

Autonomous underwater vehicle (AUV) known, as a special purpose underwater research vehicle (SPURV) is really a pocket submarine that could be used in multipurpose such as meteorology, probing the pollution of stream, military spying, exploring an underwater tunnel or wrecked ships and other purposes. With the reason of the power of battery inside of AUV is limited, the aim of this paper is to represent an effect way of control the submerging and surfacing of an AUV in order to save energy for a longer time service or a deeper and further expedition under water. In fact, there are so many ways for saving energy of the battery of AUV and in this paper, the selection of keeping permanently the horizontal direction of the AUV in any operation as the situation of a real submarine is applied. The diving and surfacing of AUV are consigned to the motor of the pump that consumes a little of energy to keep the proportion of the weight and the Archimedes force by pumping water inside or outside of the AUV. The selection of volume of pumped water is considered as a dynamic ballast mass for maintaining the horizontal equilibrium of the AUV at the time of submerging and surfacing. In the other hand, the controlling of the gravity point of AUV for maintaining a fixed position of gravity of the AUV when submerging and surfacing are the main factors of the paper that is also investigated in this paper. Finally, the motor of the propeller or thruster that always spends a great energy has committed only for forward or backward motion of the AUV. In this measure, the motor of thruster does not confronted with a great consummation of energy when submerging and surfacing in an oblique direction as almost all popular measures of control of AUV.

Estimating light-duty vehicles' contributions to ambient PM2.5 and PM10 at a near-highway urban elementary school via elemental characterization emphasizing rhodium, palladium, and platinum

The primary objective of this research is to accurately estimate light-duty vehicles' (LDVs') emissions of PM2.5 and PM10 over the course of a year within the property line of an inner-city school located adjacent to a heavily-trafficked interstate highway by measuring platinum group elements (PGEs – Rh, Pd, and Pt) along with 49 other major and trace elements. Amongst PGEs, ambient Pd concentrations were the highest, averaging 11 pg/m3 in PM10 and 4.0 pg/m3 in PM2.5 followed by Pt (3.5 pg/m3 in PM10 and 1.4 pg/m3 in PM2.5), and Rh (1.6 pg/m3 in PM10 and 0.52 pg/m3 in PM2.5). Simultaneous three-component variations in Rh, Pd, and Pt in both PM size classes at this surface site closely matched the composition of (i) a mixed random lot of recycled autocatalysts obtained from numerous LDVs and (ii) PM inside a proximal underwater tunnel open only to light-duty vehicles. Additionally, quantitative estimates of LDV contributions to ambient PM calculated by chemical mass balance modeling (CMB) were strongly correlated with PGE abundances. Therefore, PGEs predominantly originated from gasoline-driven motor vehicles validating them as unique LDV tracers. Further, CMB estimated that vehicles contributed 37% on average (12–67%) to PM10 and 49% on average (25–73%) to PM2.5. Evidence is also presented for a subset of other trace metals; i.e. Cu, As, Mo, Cd, and Sb to also be relatively strong LDV tracers. Results highlight the importance of measuring PGEs in addition to numerous other elements in PM to accurately apportion aerosols emanating from LDVs, which will better isolate public health and environmental impacts associated with the transportation sector.

Comparative Analysis of Underground Underwater Tunnel

Comparative Analysis of Underground Underwater Tunnel

The Analysis on Seepage Field of Grouted and Shotcrete Lined Underwater Tunnel

Groundwater control in underwater tunnels by drilling and blasting method is generally carried out by grouting ring, shotcrete lining (primary lining), and concrete lining. The permeable grouting ring and shotcrete lining have an important impact on seepage field. However, the currently published research models of related results are for homogeneous and isotropic single-layer unlined tunnels, ignoring the important effects of tunnel grouting circles and primary lining. If the conclusions of the relevant literature are directly used to guide the tunnel design, large errors may occur. Therefore, on the basis of previous studies, this article extends the tunnel seepage research model and incorporates the tunnel grouting ring and primary lining into the research model. The research model is more in line with actual working conditions. Based on the principle of mirror method, the seepage field of a drainage tunnel in an infinite aquifer is superposed with that of a water supply tunnel in an infinite aquifer, and the analytical solution to the seepage field of an grouted and shotcrete lined underwater tunnel in a semi-infinite aquifer is obtained, which is further verified by numerical analysis and experiment. In addition, the influence of grouting ring and primary lining parameters on seepage field is discussed by using partial differential analysis. The results show that the seepage flow of tunnel can be significantly alleviated by either reducing the permeability coefficient of grouting ring and primary lining or increasing the thickness of grouting ring and primary lining, but the water pressure of grouting ring and primary lining will increase.

Settlement behaviors investigation for underwater tunnel considering the impacts of fractured medium and water pressure

Settlement behavior plays an important role for the stability of underwater tunnel due to the different responses of fractured surrounding rock to external load. In contrast to the traditional analysis method based on continuum mechanics, the presented numerical model using improved hybrid finite element was performed to study the settlement behaviors of structure, and structural health monitoring system (SHMS) was introduced for field verification. The Nanjing Yangtze River tunnel, a typical underwater shield tunnel was selected as a case study for numerical simulation and real-time monitoring. First, an improved numerical model was developed on the basic of our previous research, which considers the impact of natural geological fractures on structure stability. Then, numerical investigation was applied to study the displacement of settlement under different boundary conditions. The differences between intact and fractured surrounding rock were discussed, which denote the response of fractured surrounding rock is significantly larger. To verify the numerical results, SHMS was employed in this project to monitor its mechanical behaviors. On the basis of the mass monitoring data, the analytical method was introduced to investigate the response of tunnel settlement to water pressure, which agreed well with the results obtained from the model of fractured surrounding rock.

Research on drivers’ visual characteristics in different curvatures and turning conditions of the extra-long urban underwater tunnels

In order to study driver’s visual characteristics under different curvatures and turning conditions in extra-long urban underwater tunnels, fixation and saccade were herein regarded as the main research objectives. In this study, we carried out real vehicle testing on curved sections with 5 different radii and straight sections of the extra-long urban underwater tunnels. The driver’s fixation characteristics were studied by using fixation distribution, fixation time, fixation frequency, fixation time ratio, and frequency ratio. The driver’s saccade characteristics were investigated by selecting the saccade angle, saccade time, saccade frequency, saccade time ratio, and frequency ratio. Accordingly, mathematical models of the driver’s fixation time, fixation frequency, saccade time, and saccade frequency under different curvatures and turning conditions in the extra-long urban underwater tunnel were established. Combined with the change of visual distance, sight distance, and sight zone, driver’s visual characteristics in the extra-long urban underwater tunnel were further analyzed. The results demonstrated that the smaller the radius of the tunnel, the more focused driver’s fixation time, the greater the psychological pressure, and the lower the safety when driving. Under the same radius, driver’s tension and risk factors were higher during turning left, while driver’s driving mentality was more relaxed and driving situation was further stable in the right-turn.

Drivers’ Saccade Characteristics in Curves of Extra-Long Urban Underwater Tunnels

Traffic accidents in extra-long urban underwater tunnels are characterized by high numbers of causalities and severe traffic congestion. Analyzing drivers’ saccade characteristics under different curvature conditions in urban underwater tunnels can provide solutions to reduce the rates of such accidents and increase traffic safety. This paper reports real vehicle tests conducted in extra-long urban underwater tunnels, on curved sections of radii of 400, 680, 1,000, 1,500, and 3,000 m, and also on straight sections. Indicators of drivers’ saccade behavior, such as saccade angle, time, and frequency, and the saccade time ratio were evaluated. The coefficient of variation was used to analyze the discreteness of the saccade angle. The driver’s saccade characteristics, such as saccade time and frequency, were explored by combining the visual distances for different curved sections. The results demonstrated that (a) small angles in the range of [0, 10°] constituted the main distribution section of the driver’s saccade angle in extra-long urban underwater tunnels, and the saccade angle discreteness increased with increase in the radius, (b) the driver’s average saccade time increased while the average saccade frequency decreased with the increase of the radius, (c) the driver’s visual load was higher for long straight sections and small-radius curves, (d) the driver’s safety was generally higher on right-curving sections than on left-curving sections.

Analytical solution for steady seepage and groundwater inflow into an underwater tunnel

Solutions of the water pressure and groundwater inflow distribution along the tunnel perimeter in a half-infinite aquifer were investigated considering the conditions of the constant head and constant water pressure. It is assumed that the circular tunnel is buried in a fully saturated, homogeneous, isotropic and half-infinite space. Coordinate transformation technique was adopted, the problem of solving the control equations of water pressure in the Cartesian coordinate was transformed to that in the bipolar coordinate system, which can significantly simplify the derivation procedure of the water pressure and inflow distribution. The validation results show the accuracy and advantage of the proposed approach.

An Analytical Continuous Upper Bound Limit Analysis of Pore Water Effect on the Tail Stability of Underwater Shield Tunnels during Construction

An analytical continuous upper bound limit analysis is developed to analyse the effects of seepage on the transverse stability of underwater shield tunnels. The approach is based on an analytical continuous upper bound limit analysis method for cohesive-frictional soils. It employs the complex variables solution of the displacement field due to tunnel deformation and movement, and the analytical solution of the pore water pressure field for steady state seepage due to pore water influx at the tunnel perimeter. The most critical slip line position and the minimum required tunnel support pressure are determined by using a particle swarm optimization scheme for various generic situations. The method is verified via finite element simulation and comparison with the solution from using rigid block upper bound limit analysis. The parametric analysis revealed among other things that both the infimum of the necessary tunnel support pressure and the most critical plastic zone increase when the hydraulic head at the ground surface increases, but decrease when the tunnel influx increases due to the fact that pore water pressure at the tunnel perimeter decreases with the tunnel influx.

Design and construction example of inadequate embedded depth of retaining piles in ventilation tower basement excavation of underwater tunnel

The ventilation tower basement excavation of Haicang Tunnel in Huli District of Xiamen City is taken as an example in this article. Owing to design alteration, the analysis of inadequate embedded depth of retaining piles is executed. Result reveals that measures of shotcrete-bolt support system, steal arch system and divisional digging method can successfully ensure the safety of the changed excavation structure. Thoughts and consideration of the calculating method of this design change is described in the end, which may be helpful to familiar constructions.

Research on Fire Smoke Controlling Effect of Submarine Road Tunnel Based on FDS

Taking submarine road tunnel as the research objective, numerical calculation model of fire smoke controlling in rectangular underwater tunnel was established by FDS. The adaptability of lateral concentrated exhaust mode in tunnels of variable widths is obtained according to analysis of smoke distribution and smoke exhausting efficiency under different working conditions. The results are as follows: The increase of width results in the decrease of smoke exhausting efficiency. In the four-lane dual-directional tunnel, the smoke exhausting efficiency is 83.4%; while that of twelve-lane dual-directional tunnel is only 55.2%. The wind velocity is higher in the area near the lateral exhaust valves; and which is lower in the area far from the exhaust valves. The influence of wind velocity for lateral exhaust valves is limited. With the increase of width, the wind velocity of cross-section decreases dramatically. In a four-lane dual-directional tunnel, the wind velocity of the right wall decreases by 32%, and that in twelve-lane dual-directional tunnel decreases by 59.6%. For large-span rectangular tunnels of eight-lane dual-directional or even wider ones, the lateral centralized exhaust mode shows poor fire smoke controlling effect.

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

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 validated by conducting laboratory evaluations. Critical factors of underwater tunnels, including the surrounding environment, lining, bottom drainage system, and other supplementary components have been represented by such system to investigate the drainage mechanism and efficiency of the designed system. The drainage system has been further optimized by analyzing the measured water pressure and flow rate. Experimental results indicate that the designed draining system is feasible for reducing the secondary lining external water pressure in the bottom of tunnels and the water pressure has been reduced significantly with high efficiency. The capacity of the proposed system to control the rapid water inflow in tunnel construction regions can be guaranteed. The factors affecting the performance of the system such as the diameter of the drainage pipe and the inlet water pressure are also discussed.

Performance-based design of joint waterproofing of segmental tunnel linings using hybrid computational/experimental procedures

Precast segmental linings of underwater tunnels, excavated by tunnel boring machine (TBM), are key components of infrastructure that is inevitably subjected to a relatively high-water table head. Many underwater tunnels experience various degrees of water leakage issues at the tunnel joints. A rigorous joint waterproofing design is indispensable to guarantee the normal operation of tunnels. However, to date, little attention has been devoted to gaining a better understanding of the water leakage behavior of joints and the associated design method. In this paper, a combined experimental- and computational-based design framework for joint waterproofing is presented, in compliance with the most recent guidelines. The proposed step-by-step design procedures incorporate the identification of design parameters and criteria, pre-test finite element (FE) analysis, experimental evaluation, and post-test FE analysis. The gasket assembly ability refers to the shear capacity check of the gasket groove during the construction stage, while the joint waterproof capacity consists of both the short- and long-term waterproof capacities of the joints in the most unfavorable deformation state during the service stage. A pre-test analysis is performed to evaluate the preliminary gasket profiles and is followed by experimental testing of the short-term waterproofing performance of the joint. A post-test FE analysis is performed to check the groove shear capacity and to predict the long-term waterproofing performance of the joint. A design case study of a recently built underwater tunnel in China is presented to illustrate the implementation of the proposed design procedures into practice. Finally, recommendations on the contribution of the governing variables on the waterproofing performance of the joint are provided, outlining crucial aspects that may be considered by engineers in the design of underwater tunnels.