Papers by Keyword: Tunnel

Abstract: Subsurface geophysical investigations are useful for minimization and optimizing the association of conventional direct investigation methods, resulting in faster and effective advancement of underground development systems. Geophysical techniques provide expensive and cost-effective ways to enhance data obtained by direct exploratory techniques such as borehole drillings, trial test pits and in situ testing, confirming local anomalies that may not be distinguishable by other methods of investigations.In the present study, the operation of Seismic Refraction Method (SRT) in urban tunnelling is investigated during the planning phase (before construction). The lithology interpreted using the SRT technique is compared to a nearby executed borehole log and found to be comparable. A cost and duration comparison between the direct system (boring) and the seismic refraction method for a 1.0 km tunnel stretch is also carried out. It is revealed that the use of SRT required only 2.5 days, whereas borehole drilling takes a much longer duration, 17 days, to perform and complete the same task. The use of SRT reduces exploration duration by over 7.0 times compared with the boring method. The cost required for conducting SRT is 425,000 INR, whereas the borehole drilling technique is 2,800,000 INR, which is almost 6.5 times less than the boring method. This demonstrates that SRT is significantly more efficient in time and cost than borehole drilling.

Abstract: For the creation of underground works such as road and railway tunnels, critical infrastructure facilities, collectors, multi-purpose halls, it is necessary to excavate rock material from the massif. This generates surplus and unnecessary rock material, which in most cases ends up as waste in a nearby stockpile or waste dump. Often this material can meet the quality requirements for construction aggregate. Therefore, this material can be reused as a source of aggregate, thereby reducing construction costs in a circular economy. The article briefly describes the methodology of the evaluation and testing of waste rock from tunnels for various purposes of its reuse as aggregate.

Abstract: There is an intensive construction of sewage collectors in the cities. The main structural material used in the construction of collector tunnels is reinforced concrete. Services engaged in the operation of sewage systems, increasingly began to face the destruction of concrete of non-pressure sewer collectors as a result of gas corrosion. Concrete corrosion takes place only in non-pressure manifolds, in the protruding part of the water pipeline or tunnel. The maximum intensity of corrosion is observed in the area, adjacent to the axis of the arch. Сorrosion damage can occur intensively on the walls and in the zone of variable water level. The article analyzes the causes leading to corrosion of reinforced concrete in tunnels.

Abstract: Construction of the Považský Chlmec Tunnel on the D3 Highway in the stretch Žilina (Strážov) – Žilina (Brodno) is being finished and the last structure before installation of the technological equipment has been a concrete pavement and construction works related to design and construction of the pavement. The paper describes not only the issue of road structural layers according to the regulation TP098 Design of Cement Concrete Pavements on Roads, but especially on a specific example of a tunnel already built we demonstrate general particularities of road surfaces in road and highway tunnels. These are, in particular, engineering requirements on the subgrade and possibilities of its drainage, design of joints of the cement concrete pavement in relation to the tunnel lining design, ensuring the necessary long-term roughness of the road surface, design of entries of utility lines (cables, drains) below the road surface, structural details connected with placement of kerbs and channel drains, lay-bys, impacts of use of self-extinguishing road drainage components in the load bearing system of the tunnel lining and other seemingly independent structures, which, however, in the confined tunnel space influence each other substantially. The paper focuses also on construction of the individual road courses with a recommendation for measures to adopt in order to eliminate damage to the tunnel structures completed (in particular, pavements, channel drains and kerbs), coordination of the other works in the tunnel ensuring safety of all workers, logistics (transport of pavers and cement concrete mix) and other apparently tiny details, which result in safe and fast work when placing the road courses in a restricted tunnel space. In the paper, the authors have taken into account requirements of the road engineering segment and also geotechnical requirements and particularities of the tunnel construction and point out the necessity of a multi-professional approach to the design to achieve an optimal solution. Based on their own experience, at the end of the paper, the authors give recommendations on amending the standards and regulations, which in some cases do not allow for construction of road surfaces in tunnels (i.e. deep under the ground).

Abstract: With the rapid growth of cities it is considered that around 75% of the world’s population will live in cities by 2050. Estimates are that the population moving to cities are approximately 172,800 persons per day [1]. This increased demand on cities has resulted in further technological advancement in terms of infrastructure. Although the rail industry has significantly advanced in terms of driverless capability, open gangway train systems and real time monitoring it is important that our awareness of fire safety advances at the same rate.In the past, tunnel and operational fire strategies considered assisted evacuation for persons with reduced mobility (PRM) by on-board staff members, while allowing able bodied persons the ability to self-evacuate to a point of safety outside the incident tunnel. As we move into a future with further automation and less on-board train staff, it may be time to re-evaluate our current thinking in terms of tunnel evacuation strategies for Persons with Reduced Mobility.The aim of this paper is to open the discussion in terms of fire safety in tunnel systems, in particular provision of walkways and the effect on egress within tunnels. The widths of walkways are key factors in the pace at which passengers can disembark from a train onto a walkway.Although there is an active effort to improve walkway provisions within tunnels, the minimum acceptable width limit is still open for debate. This ultimately comes down to a balance between cost (monetary, environmental) and level of acceptable risk.

Abstract: This paper covers design diagrams and algorithms for determining the strain state of soil mass in case of its underworking. When tunnels are constructed in restrained urban conditions peculiar to megapolises, there is an acute problem related to the assessment of their influence on the existing above-and underground facilities. The strains of buildings and structures that occur as a result of underground construction work may have an impact on the operation reliability of these facilities. Russian regulatory documents in the area of underground urban construction strictly govern the basic parameters of the subsidence trough, such as maximum vertical subsidence, curvature, inclination, etc., for most of the existing underworked structures. Such facilities include both buildings and structures of various purposes above ground and different types of utilities (roads and railways, pipelines, cable lines, etc.). The method described in the paper offers the use of an integral quantity of "volume loss" when tunneling is performed by tunnel-boring machines. The "volume loss" term shall be understood to mean the distance between tunnel lining and soil mass, which initially occurs due to the difference between rotor diameter and lining outside diameter. There are also a number of other technology factors affecting the increase of this parameter, and their quantitative assessment is given in this paper. The method proposed in this paper makes it possible to promptly assess the impact of tunneling operations on the existing underworked structures with account of basic influencing factors.

Abstract: In the heart of the processes of formation of physical and mechanical properties of secondary lining of underground structures is the residual water-cement ratio, which indicates the extraction of the mixing water of the concrete mixture under the action of external pressure forces. This article examines the nature of the redistribution of the mixing water in the concrete lining of the tunnels. Under the influence of radial and axial forces from laid concrete mix there is an increase in water-cement ratio in the direction from the sole to the vault head of the tunnel. This leads to deterioration of physical and mechanical properties of the lining in the roof part of the tunnel. When calculating the strength and water resistance of the secondary concrete tunnel lining the characteristics of the concrete type by strength and waterproof, adjusted by the weakest part of the lining – its roof part – should be taken into account. The analysis of influence on the technology of erection of the lining is given.

Abstract: The article is involved with study of fire resistance of concrete for tunnel linings. It summarises the problems of present knowledge of concrete resistance in tunnels and deals with behaviour of concrete particular parts at exposure to high temperatures. Further possibilities of fire resistance improvement for production of concretes together with fire prevention are described in this paper.

Abstract: In the year 2013 the modernization of a railway track between the cities Rokycany and Plzeň had began. This project, which is part of the third Czech Railway Transit Corridor includes partly reconstruction of the existing track and partly construction of a completely new track. Because of this, in the part between Ejpovice and Plzeň, new structures like bridges, culverts as well as tunnels have to be done. Two tunnel tubes under the hills Homolka and Chlum will be excavated by S-799 Herrenknecht tunneling machine and after its completion they will be the longest railway tunnels in the Czech Republic. The complete length will be 4150 meters. Tunnel lining segments are made of fiber-reinforced concrete.

Abstract: In some tunnels of railway lines located in water-rich region, due to the long-term water leakage and erosion, the foundation of railway lines showed large uneven settlement deformation, so the above concrete roadbed slabs also experienced uneven settlement accordingly. The smoothness of railway tracks diminished, and the speed of passing trains had to be limited to ensure safety. To restore the smoothness of the tracks, a dedicated polymer injection technology for quick uplift rehabilitation of uneven settlement concrete roadbed slabs was studied on site just within the specified daily skylight time (about 3 hours every day) of the railway lines. A hydrophobic polymer with low-viscosity, quick-setting and high-strength properties was used for injecting, filling and uplifting the concrete slabs in water-rich foundations. The high-precision electronic levels were adopted to monitor rising height of the tracks in real time. After rehabilitation, the filling quality of polymer injection under roadbed slabs was examined using Φ50 mm core samples and the strength of hardened polymer was verified by compressive strength test. Results indicated that the polymer could uplift the concrete roadbed slabs effectively and restore the smoothness of railway tracks accurately even in the water-rich environment. The research can provide some valuable references for quick rehabilitation of uneven settlement concrete roadbed slabs in water-rich tunnels.