Precast Concrete Tunnel Linings Research Articles

Contribution of Closed Ties to Shear Strength of GFRP-Reinforced Precast Concrete Tunnel Lining Segments: Experimental and Analytical Study

Contribution of Closed Ties to Shear Strength of GFRP-Reinforced Precast Concrete Tunnel Lining Segments: Experimental and Analytical Study

Precast CSA-based concrete tunnel lining segments reinforced with GFRP bars: Challenges and opportunities

This research study investigates the potential of using Calcium Sulfoaluminate (CSA) binder as a sustainable alternative to ordinary Portland cement (OPC) in the production of precast concrete tunnel lining (PCTL) segments. The effectiveness of CSA-based concrete, reinforced with Glass Fiber-Reinforced Polymer (GFRP) bars, was examined through an experimental program. Comparative analyses, including analytical, experimental, and Life Cycle Assessment (LCA) comparisons, were conducted with OPC-based segments reinforced with traditional steel. The results indicate that the proposed CSA/GFRP solution has the potential to improve sustainability in mechanized tunnelling and prefabrication. A case study is also presented to support these findings.

Effect of test parameters on the punching-shear strength of precast tunnel segments reinforced with GFRP bars

While assessing the load cases is crucial for designing the precast concrete tunnel lining (PCTL) segments, none of the tunnel-specific standards or codes explicitly consider punching-shear loads. This study aimed at determining the structural performance of full-scale precast concrete tunnel segments reinforced with glass fiber-reinforced polymer (GFRP) bars. The segments were constructed with a rhomboidal shape measuring 2100 × 1500 × 250 mm and subjected to point loading on their extrados surfaces until failure. Such loading simulates the geotechnical exposure conditions surrounding tunnels, such as rock expansion. The effects of concrete strength and GFRP flexural reinforcement ratio on the punching behavior were analyzed and are discussed herein. The load–deflection response, failure mode, punching strength, cracking behavior, reinforcement and concrete strain, deformability, and energy absorption were all evaluated in the experiments. The results reveal that increasing both the flexural reinforcement ratio and concrete strength enhanced the punching response and decreased crack width. In addition, using HSC in tunnel segments yielded higher pre-cracking stiffness, punching-shear capacity, and energy absorption. A theoretical investigation involving a comparison between predictions of the FRP-reinforced concrete slab design provisions and experimental results was performed to assess the applicability of the current punching equations for PCTL segments. The equations in the FRP-reinforced concrete codes predicted the punching capacities conservatively, while the researchers’ proposed equations overestimated. Moreover, CAN/CSA S806-12 showed the most accurate prediction of the punching capacity even if the concrete compressive strength exceeded 60 MPa.

Experimental and analytical investigation of precast fiber-reinforced concrete (FRC) tunnel lining segments reinforced with glass-FRP bars

A hybrid use of glass fiber-reinforced polymer (GFRP) reinforcement and fiber-reinforced concrete (FRC) could be a viable option for producing durable precast concrete tunnel lining (PCTL) segments. There is, however, a gap in the literature regarding the behavior of GFRP-reinforced FRC PCTL segments with typical amounts of reinforcement. This paper presents results obtained from both experimental and analytical studies on the behavior of GFRP-reinforced FRC PCTL segments under bending load (flexure). Four full-scale tunnel segment specimens were constructed and tested monotonically under three-point bending load. The influence of concrete type, reinforcement ratio, and tie configurations on the cracking behavior, deflection behavior, failure mechanism, load-carrying capacity, strain behavior, and deformability was evaluated. There is a limited analytical procedure available to predict the shear and flexural capacities of GFRP-reinforced FRC PCTL segments. Therefore, an analytical investigation was carried out in order to propose and evaluate different methods for predicting the flexural and shear capacities of such elements. The results indicate that the use of FRC significantly improved the cracking behavior and failure mechanism while also increasing the load-carrying capacity and deformability by 12% and 71%, respectively. Increasing the reinforcement ratio by 86% enhanced the post-cracking stiffness and peak load by 92% and 31%, respectively, while reducing the service-load crack width by 57%. According to the analytical investigation, the introduced direct method based on the stress–strain behavior of the FRC and the proposed simplified method based on ACI 440.1R-15 could predict the flexural capacity of GFRP-reinforced FRC PCTL segments with high accuracy. Furthermore, the method proposed to modify CAN/CSA S806-12, R2017 to consider the contribution of fibers in shear transferring mechanism yielded rational conservative values for the shear capacity of GFRP-reinforced FRC PCTL segments.

Quasi-static cyclic behavior of precast high-strength concrete tunnel segments reinforced with GFRP bars

The cyclic behavior of fiber-reinforced polymers (FRP) reinforced precast concrete tunnel lining (PCTL) segments under quasi-static cyclic flexural loading has not yet been experimentally tested and reported on in the literature. This study investigated the cyclic behavior of glass-FRP (GFPR) reinforced precast high-strength concrete (HSC) tunnel lining segments. Full-scale segments measuring 3100 × 1500 × 250 mm were tested under quasi-static cyclic flexural loading. Two cycles of loading and unloading were applied at 1.25%, 2.5%, 5%, 10%, 25%, 50%, and 75% of the maximum displacement obtained from the static testing results, followed by a single cycle up to failure. The test parameters included concrete compressive strength, longitudinal reinforcement ratio and transverse reinforcement configuration (closed ties versus double U-shaped ties). The experimental findings of this study revealed that the GFRP-reinforced HSC PCTL segments exhibited stable hysteretic response until failure. In addition, the test results show that the GFRP-reinforced HSC PCTL segments were able to achieve adequate ductility indexes as well as deformability limits. A theoretical prediction according to the North American codes and design guidelines, including flexural capacities, cracking moment, and crack width, was made and the results compared to the experimental results. This research illustrates the advantages of using HSC for PCTL segments internally reinforced with GFRP bars under quasi-static cyclic flexural conditions.

Development of strength interaction diagrams for designing precast concrete tunnel lining segments reinforced with GFRP bars

Replacing conventional steel reinforcement with noncorroding glass fiber-reinforced polymer (GFRP) reinforcement can be an effective solution to mitigate the corrosion problem in precast concrete tunnel lining (PCTL) segments. PCTL segments should be effectively designed to withstand the applied load during production, transportation, construction, and service stages. The literature, however, offers limited design recommendations or guidelines for designing GFRP-reinforced PCTL segments. In this study, an experimental program was conducted to investigate the effect of reinforcement ratio and tie configuration on the behavior of GFRP-reinforced PCTL segments at the service and ultimate stages. Novel procedures and equations were developed to obtain axial load–bending moment interaction diagrams at the ultimate and service stages. In addition, interaction diagrams were developed to consider the creep-rupture stress limits in GFRP bars. Furthermore, axial load–shear-strength interaction diagrams were developed for GFRP-reinforced PCTL segments, as well as a simplified procedure to control cracking. Afterward, a parametric study was performed to evaluate the effect of concrete compressive strength, reinforcement ratio, and cross-sectional thickness on the axial load–bending moment interaction diagrams of GFRP-reinforced PCTL segments. The analytical results were compared to the experimental results from the current study and the literature. The comparison revealed that the proposed analytical procedure was suitable for designing GFRP-reinforced PCTL segments.

Structural performance of corroded precast concrete tunnel lining

Based on the material constitutive models obtained according to the static load test and the finite element simulation conducted by LS-DYNA, the structural performances of the precast concrete tunnel lining (PCTL) of Shanghai Metro under different loading and corrosion cases were analyzed. The results indicated that weakened stiffnesses of the corroded 8° joint, 73° joint, and 180° section led to the redistribution of the internal force, which in turn degraded the structural performance of PCTL. The deformability and unload-carrying capacity of the unloaded PCTL without corrosion were 60% and 30% of those of the overloaded PCTL, respectively, which meant that unloaded PCTL is more vulnerable. PCTL with corroded intrados side rebars and bolts is common in practice. Under this corrosion type, with the increase in corrosion degree (within 0.3), the deformability of PCTL had a maximum decrease of 55.8% (overloaded), and the load-carrying capacity of PCTL had the maximum decrease of 52.1% (overloaded) and 35.7% (unloaded). The corrosion of the intrados steel bars of the bottom segment and bolts of the 73° joint was the most unfavorable condition for the structural performance of PCTL. Regardless of overloaded or unloaded, the corroded PCTL is in a high-risk state. In this study, the water and soil load and the nonuniform space distribution of corrosion were not comprehensively considered, and the constitutive model of the corrosion-expanded concrete was not accurate enough, which needs to be improved in the future.

Three-dimensional numerical study of the reactive powder concrete segments in tunnel lining

Abstract The tunnel lining systems act as lines of defence against the forces and geotechnical situations. The use of precast concrete tunnel linings (PCTLs) has been escalating due to its effective and economical installation process. The tunnels usually suffer from the premature deterioration due to corrosion of the reinforcement and thus need maintenance. Corrosion leads to the distress in PCTL leading to the cracking and finally the scaling of concrete. This study aims to assess the structural durability performance of reactive powder concrete (RPC) as the material of tunnel lining segments compared to reinforced concrete (RC) and high performance concrete (HPC). The numerical findings indicated that the maximum load capacity of PRC-PCTL segments was greater than that of the corresponding RC and HPC segments. Regarding the findings, PRC is a very significant option for conventional segments. The high strength of PRC can decrease the thickness of the PCTL segments, resulting in the decreased material cost. Also, PRC-PCTL segments can eliminate the laborious and costly production of RC segments and mitigate the corrosion damage and thus enhance the service life of lining segments.

A multi-criteria decision-making based approach to assess the sustainability of concrete structures

The use of sustainability assessment tools is gaining importance in the construction sector. There exist several methods with different approaches and scopes; however, there is still no consensus about which method should be used to deal with the sustainability assessment of concrete structures. Among these, the multi-criteria decision-making based approach called MIVES seems to be a suitable and flexible model that allows taking into account all those indicators and parameters (of economic, social and environmental nature) involved in the sustainability assessment of concrete structures. The objective of this research document is two-fold: (1) to expose the basis and concepts related with the MIVES model as a sustainability assessment tool and (2) to present 3 real study cases (wind precast concrete towers; steel fibre reinforced precast concrete tunnel linings and reinforced concrete pile-supported slabs) in which this model has been used to make decisions. The authors of this research consider that similar approaches should be included in future national and international structural concrete guidelines (as the Spanish Structural Concrete Code does) to perform sustainability analysis of new designed concrete structures.

ANALYSIS AND DESIGN OF MRT’S CIRCULAR TU

ABSTRACT Jakarta MRT was one of solution to solve the traffic jam in Jakarta. There are two physical constructions which serves as the main infrastructure of Jakarta MRT, elevated and underground track. It is not only the first MRT in Indonesia but also, the first large-scale underground works in Jakarta. The physical construction of underground structure became an interesting case to be researched. The use of precast concrete tunnel lining (PCTL) segment was necessary to hold the loads and to provide the space for underground track. In designing the tunnel lining, calculation of the member forces and safety check are necessary to determine the amount of rebar and the dimension, and also to know the value of safety, so, the tunnel lining can be used as the function. According to the guidelines for the design of shield tunnel lining issued by International Tunnelling Association (ITA, 2000), the member forces of tunnel lining could be calculated by (1) Elastic Equation Method, (2) Bedded Frame Method, (3) Finite Element Method (FEM). In this research, the member forces of tunnel lining are calculated using analytical method, without computer program. Therefore, method (1) is used to know the value of each member forces to be used for designing the reinforcement bars. The member forces are analysed for tunnel lining with 6.8 m outer diameters, 1.5 m width and 0.25 m thickness in Jakarta MRT CP106 (Bundaran HI). Based on research which has been done, obtained the maximum values for positive bending moment in the tunnel crown (I¸ = 0°) is 101.352 kN.m, for negative bending moment in the tunnel axis (I¸ = 90°) is -281.394 kN.m. In contrary, the value of maximum axial force is in the tunnel axis (I¸ = 90°) is 1094.538 kN, for minimum axial force is in the tunnel crown (I¸ = 0°) is 904.674 kN. While, the value of maximum shear force is in (I¸ = 120°) is 118.740 kN, for minimum shear force is in (I¸ = 30°) is -66.866 kN. The result of safety checks against member forces in tunnel lining, the value of nominal bending moment multiplied by reduction factor (I• · Mn) is 296.263 kN.m, bigger than the value of ultimate bending moment (Mu) is 281.394 kN.m. For the value of nominal shear force multiplied by reduction factor (I• · Vn) is 136.095 kN, bigger than the value of ultimate shear force (Vu) is 118.740 kN. While, safety check against thrust force of shield jack obtained the value of maximum compressive stress of concrete segment (𝜎𝑐) is 5.016 MN/m2, bigger than the value of allowable stress (𝜎𝑐𝑎) is 16 MN/m2. Keywords: Jakarta MRT, underground, tunnel lining, member forces, Elastic Equation Method.

Mechanical Behavior of RC and SFRC Precast Tunnel Lining Segments under Chloride Ions Exposure

AbstractThe structural integrity of precast concrete tunnel lining (PCTL) segments largely depends on its durability performance. The ingress of chloride ions into PCTL segments can induce reinforc...

Exploratory study of ultra-high performance fiber reinforced concrete tunnel lining segments with varying steel fiber lengths and dosages

Ultra-high performance fiber-reinforced concrete (UHPFRC) is an emerging material exhibiting superior mechanical and durability properties. However, its application in precast concrete tunnel linings is lagging due to lack of experimental data and adequate design provisions. This study is a preliminary investigation of UHPFRC tunnel lining segments incorporating various steel fiber lengths and dosages. The mechanical performance of UHPFRC tunnel lining segments was investigated. Flexural and edge-point load tests were conducted on 1/3-scale UHPFRC tunnel lining segments to evaluate its bending and thrust load resistance. The main studied variables were the steel fiber lengths and dosages. Results showed that UHPFRC tunnel lining segments incorporating shorter steel fibers exhibited higher cracking and peak loads compared to that of similar segments made with longer fibers. Furthermore, the shorter fibers enhanced the strain hardening phase, leading to more stable multiple micro-cracks and higher resistance to growth of macro-cracks. Conversely, longer steel fibers better improved the post-peak strain softening of the lining segments, achieving more ductile failure. The load carrying capacity of UHPFRC lining segments linearly increased with higher fiber dosage and followed the rule of mixtures. Moreover, steel fibers enhanced the cracking behavior under both thrust load and concentrated load compared to that of segments without fibers.

Chloride Ion Penetration in RC and SFRC Precast Tunnel Lining Segments

Steel corrosion induces distress in concrete structures, resulting in the cracking and spalling of the concrete cover, which accelerates further damage. Chloride ions (Cl–) and carbonation are the primary causes of steel corrosion in concrete. This study investigates the effects of Cl– in precast concrete tunnel lining (PCTL) segments through conducting various tests on cylindrical cores extracted from conventional reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) segments. The full-scale PCTL segments were fabricated and cured at an industrial precast plant. Experimental results show that the external specimens (extrados and intrados faces) of both the RC and SFRC PCTL segments exhibited lower Cl– penetration due to surface treatment using a cement slurry. The Cl– diffusion coefficient was a function of the exposure period and concentration of the salt solution for both the RC and SFRC segments. SFRC PCTL segments better resisted the ingress of Cl– than control RC segments due to a barrier effect induced by steel fibers (SF), which helped inhibiting the penetration of Cl– into the hardened concrete. This study demonstrates the potential of SFRC as a more durable alternative for precast segmental tunnel linings compared to conventional RC.

Mechanical Performance of RC and SFRC Precast Tunnel Lining Segments: A Case Study

Tunnels play a key role in facilitating the movement of people, goods, and services. The functionality of tunnels depends on the structural and durability performance of its lining system. Tunnel lining systems act as lines of defense against large overburden loads and complex geotechnical surrounding conditions. In this study, the structural behavior of precast concrete tunnel lining (PCTL) segments from a subway extension tunnel project in Canada was investigated. Flexural monotonic and cyclic load tests were performed on full-scale conventional reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) PCTL segments to evaluate their bending resistance. Moreover, a thrust load test was conducted to simulate the thrust loading action during tunnel boring machine operation. As expected, flexural test results indicate that the peak load-carrying capacity of RC segments was higher than that of the SFRC segments. However, SFRC segments exhibited higher cracking load and more stable post-peak cracking behavior compared to that of RC segments. RC and SFRC segments exhibited similar behavior during thrust load tests. Both types of segments satisfied the design flexural capacity and thrust loading criteria for monotonic and cyclic loads. The SFRC crack control capability supports its potential as an alternative for conventional RC tunneling segments.

Experimental study on settlement and punching behavior of full-scale RC and SFRC precast tunnel lining segments

The overall stability of a segmental tunnel lining ring is highly dependent on the structural integrity of its individual precast segments, which provide protection against the surrounding exposure conditions. In this study, the settlement and punching behavior of full-scale conventional reinforced concrete (RC) and steel fiber-reinforced concrete (SFRC) precast tunnel lining segments fabricated for a subway tunnel in Canada were investigated. Precast concrete tunnel lining (PCTL) segment specimens were subjected to mid-span load on their intrados faces. Such loading can be induced as a result of vehicular accidents inside the tunnel and/or soil settlement underneath the PCTL segments. Moreover, a punching test was conducted to replicate the expansion of rocks or other geotechnical surrounding conditions above or underneath the tunnel segments. The experimental results showed that the peak load carrying capacity of the RC segments was higher than that of the SFRC segments for both the settlement and punching behavior. However, SFRC segments exhibited higher initial cracking load, more stable post-peak cracking pattern compared to that of the RC segments and significant reduction in crack width. This makes SFRC attractive for the fabrication of segmental tunnel linings where the initial cracking is a governing criterion. Furthermore, it was confirmed that both the tested RC and SFRC PCTL segments satisfied common settlement and punching loads design criteria.

STOREBAELT EASTERN RAILWAY TUNNEL: CONSTRUCTION.

Keywords AS STOREBAELTFORBINDELSEN, MT GROUP, MONBERG & THORSEN, DYCKERHOFF & WIDMANN, CAMPENON BERNARD, SOGEA, KIE TUNNELS, RAILWAYS, CONSTRUCTION, BORING, CROSS PASSAGES, HAND, MINING, METHODS, CUT AND COVER, CIVIL ENGINEERING, WORKS, GEOLOGY, WATER, PRESSURE, EARTH, BALANCE, MACHINES, MACHINERY, TBM, TUNNELLING, MODIFICATION, UNDERSEA, SUBMARINE, DEWATERING, CRYOGENICS, FREEZING, JUNCTIONING, GLACIAL, TILL, GROUND, TREATMENT, ONSITE, MANUFACTURING, HIGH, STRENGTH, DURABILITY, CONCRETE, LININGS, EPOXY, COVERED, COATED, REINFORCEMENT, CAGES, PROJECTS, MANAGEMENT, CONTRACTS, BORED, JOINT VENTURES, BEHAVIOUR, ALIGNMENT, SURVEYS, MUCK, DISPOSAL, SEABED, WATER, CON STOREBAELT, EASTERN DENMARK, SCANDINAVIA... Show All

Robots used for Hong Kong mass transit railway repair

The repair of tunnel linings on the Hong Kong Mass Transit Railway by means of a unique robotic system was the subject of the British Tunnelling Society Meeting at the Institution of Civil Engineers on November 24, 1994. Inspections during the mid 1980s revealed the need for repair in certain tunnels, particularly where aggressive sea water penetrating the ground was slowly percolating through the precast concrete tunnel linings, causing extensive spalling. A repair method had to be devised, which could be executed within the daily 5 o'clock shut down period to avoid disruption to railway operation. The concept eventually established after considerable research and trials was: To seal existing leaks; To remove cover concrete to the inside face reinforcement; To remove the corroding near face reinforcement wherever possible; To replace the existing cover concrete with a thicker (75 mm) layer of high density, low permeability (<1 x 10 (-12m/s) shotcrete to induce saturation of the existing lining to create a nil oxygen environment, thereby stabilizing corrosion.

Development and use of precast concrete tunnel linings : McCusker, T G Proc 1989 Rapid Excavation and Tunnelling Conference, Los Angeles, 11–14 June 1989P369–384. Publ Littleton: SME, 1989

Development and use of precast concrete tunnel linings : McCusker, T G Proc 1989 Rapid Excavation and Tunnelling Conference, Los Angeles, 11–14 June 1989P369–384. Publ Littleton: SME, 1989

Comparisons, experiences and development of the use of precast concrete tunnel linings in Europe, North America and the Far East : Hart, A J R Proc 1987 Rapid Excavation and Tunnelling Conference, New Orleans, 14–17 June 1987V1, P423–431. Publ Littleton: Society of Mining Engineers, 1987

Comparisons, experiences and development of the use of precast concrete tunnel linings in Europe, North America and the Far East : Hart, A J R Proc 1987 Rapid Excavation and Tunnelling Conference, New Orleans, 14–17 June 1987V1, P423–431. Publ Littleton: Society of Mining Engineers, 1987

Precast concrete tunnel linings — A review of current test procedures : Lance, G A Construction Industry Research and Information Association technical note 104, May 1981, 60P

This note describes 28 tests on complete rings, individual segments and joints of precast concrete for tunnel linings. Strength tests have been reported on behaviour in compression, bending, combined bending and compression, and resistance to ram loading and pullout. It is concluded that there is not at present an economic case for constructing a full scale test rig. (TRRL)