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A utility tunnel is an infrastructure that consolidates multiple municipal pipeline systems into a shared underground passage. As long linear structures inevitably cross different soils, this paper aims to accurately assess the seismic damage to a shallow-buried utility tunnel in a non-homogeneous zone by employing a viscous-spring artificial boundary and deriving the corresponding nodal force equations. The three-dimensional model of the utility tunnel-soil system is established using finite element software, and a plug-in is developed to simulate the three-dimensional oblique incidence of SV waves with a horizontal non-homogeneous field. In this study, the maximum interstory displacement angle of the utility tunnel is used as the damage indicator. Analysis of structural vulnerability based on IDA method using PGA as an indicator of seismic wave intensity, which considers the angle of oblique incidence of SV waves, the type of seismic waves, and the influence of the nonhomogeneous field on the seismic performance of the utility tunnel. The results indicate that the failure probability of the utility tunnel in different soil types increases with the incident angle and PGA. Additionally, the failure probability under the pulse wave is higher than that under the non-pulse wave; Particular attention is given to the states of severe damage (LS) and collapse (CP), particularly when the angle of incidence is 30 degrees and the PGA exceeds 0.6g, conditions under which the probability of failure is higher. Additionally, the failure probability of the non-homogeneous zone is greater than that of sand and clay; the maximum interlayer displacement angle increases with the incident angle, accompanied by greater PGA dispersion, indicating the seismic wave intensity. The maximum inter-layer displacement angle increases with the incident angle, and the dispersion of the seismic wave intensity indicator (PGA) becomes greater. This paper proposes vulnerability curves for different working conditions, which can serve as a reference for the seismic design of underground structures.

期刊论文 2025-10-01 DOI: 10.1016/j.soildyn.2025.109537 ISSN: 0267-7261

Large-span corrugated steel utility tunnels are widely used owing to their large spatial spans and excellent mechanical properties. However, under seismic forces, they may experience significant deformation, making repair challenging and posing a serious threat to personal safety. To study the seismic performance of corrugated steel utility tunnels, an equivalent orthotropic plate was introduced, and a simplified three-dimensional refined finite element model was proposed and established. Considering the site conditions of the structure, the structural parameters, and different seismic input conditions, a detailed analysis was conducted using the endurance time analysis method. The results indicated that the simplified model agreed well with the experimental results. The seismic input conditions significantly affected the relative deformation of the structure. Under the action of P waves (compression waves) and P + SV waves (compression and shear waves), the deformation of the upper part of the structure was relatively uniform, whereas under the action of SV waves (shear waves), the deformation of the crown was more evident. The greater the burial depth of the structure, the stronger the soil-structure interaction, and the smaller the increase in relative deformation. In soft soil, the structure was more likely to be damaged and should be carefully observed. Additionally, increasing the corrugation profile of the steel plates during the design process was highly effective in enhancing the overall stiffness of the structure. Based on the above calculation results, the relative deformation rate was proposed as a quantitative index of the seismic performance of the structure, and corresponding values were recommended.

期刊论文 2025-09-01 DOI: 10.1016/j.soildyn.2025.109457 ISSN: 0267-7261

Probability-based seismic fragility analysis provides a quantitative evaluation of the seismic performance exhibited by structures. This study introduces a framework to perform seismic fragility analysis of utility tunnel and internal pipeline system considering wave passage effect of the ground motion spatial variation. The numerical model of a double-beam system resting on a nonlinear foundation is established to simulate the soiltunnel-pipeline interactions. 17 pairs of earthquake records are chosen and scaled as inputs at the outcrop. One-dimensional (1D) free-field analyses are conducted to obtain the ground motion time histories at the bottom slab of the utility tunnel, and then incremental dynamic analysis (IDA) is performed for the utility tunnel-internal pipeline system. The damage states (DSs) are defined by the maximum joint opening for the utility tunnel and maximum strain for the internal pipeline, and the peak bedrock velocity (PBV) is determined to be the most representative intensity measure (IM) for developing the seismic fragility curves. The seismic fragility curves of the system are constructed using the joint probabilistic seismic demand model (JPSDM) and Monte Carlo sampling method. The research findings indicate that: (1) the framework proposed in this study is suitable for the fragility assessment of long-extended utility tunnel-internal pipeline system; (2) the utility tunnel and internal pipeline as a system exhibit greater fragility compared to either one of the components, and the JPSDM and Monte Carlo sampling method for the system fragility analysis is more precise than the first-order bound method; (3) the proposed fragility curves in this study provide quantitative damage probabilities for the individual components and system under different seismic intensity levels. (4) The IM values corresponding to 50% exceedance failure probability of the whole system is 1%-3% lager than that of the upper bounds, and it is 3% to 5% less than that of the lower bounds. The conservative upper bound is a more suitable approximation for system fragility. (5) It should be noted that the obtained fragility curves are valid for the considered tunnel-pipeline structure and site conditions. For different tunnel structures and site conditions, the fragility curves can be constructed following the same steps outlined in this study.

期刊论文 2025-04-01 DOI: 10.1016/j.tust.2025.106441 ISSN: 0886-7798

This research combines scaled model experiments with theoretical analysis to investigate the impact of underground utility tunnels (UUTs) on foundation bearing capacity and to examine the interaction between soil-rock composite strata and the stress-strain responses of the tunnel. The findings indicate that UUTs alter the foundation mechanism by reducing soil depth, streamlining the load transfer path, and causing stress to converge at the tunnel's top. Additionally, the results reveal that the influence range of the tunnel on both sides is approximately 1.5 times its width and remains unaffected by the position of load application, the tunnel's burial depth, or the width of the composite stratum. Moreover, when the width of the soil-rock composite stratum equals the width of the tunnel, the tunnel experiences a laterally flexural stress state. Within this specific stratum context, the central axis area of the tunnel roof and the connection with the side panels represent the core sensitive areas for crack initiation and propagation. In the failure scenario, the tunnel roof displays typical characteristics of fracture and depression, with the damage degree decreasing from the load center towards both ends. Meanwhile, the side panels do not exhibit characteristics of plastic deformation. This research provides a theoretical framework for the design, construction, and maintenance of UUTs, emphasizing its practical significance in engineering.

期刊论文 2025-03-05 DOI: 10.1038/s41598-025-91893-1 ISSN: 2045-2322

Corrugated steel-plate culverts, particularly in horizontal ellipse form, are commonly used in large-span projects. Despite the guidelines on plate radius ratios, the impact of these ratios on mechanical properties remains unexplored. This gap highlights the need for research to guide utility tunnel design because existing studies mainly focus on round culverts compressed into elliptical shapes. Therefore, this study conducted backfill, simulated vehicle live load, and ultimate-load tests on two horizontal-ellipse corrugated steel utility tunnel structures with different top-side plate ratios to examine their response characteristics under various load conditions. Moreover, they were compared with those of existing design methods to offer new insights for the design analysis of soil-steel structures. The results demonstrated that the ratio significantly influenced bending moment distribution, and the critical was concentrated beneath the loading pad for live loads. The ultimate capacity varied with the ratio, with the higher ratio specimen reaching approximately 92.5 % of the capacity of its counterpart. Both specimens failed via tri-plastic hinge mechanisms, with reduced capacity as corrugations flattened. The Canadian Highway Bridge Design Code, which considers thrust force and bending moment, accurately predicted bearing capacity than the other methods in this study. These findings are vital for optimising design and ensuring safety in horizontal-ellipse corrugated steel utility tunnels.

期刊论文 2025-01-01 DOI: 10.1016/j.jcsr.2024.109159 ISSN: 0143-974X

A horizontal non-homogeneous field adversely affects the seismic resistance of both the utility tunnel and its internal pipes, with seismic waves obliquely incident on the underground structure causing more significant damages. To address these issues, this study, based on a viscous-spring artificial boundary, derives and validates the equivalent junction force formula for the horizontal non- homogeneous field. It then establishes a three-dimensional finite element model of the utility tunnel, pipes, and surrounding soil to obtain the acceleration and strain responses of the utility tunnel and its internal pipes under seismic loading. Finally, it investigates the impact of different incidence angles of shear waves (SV waves) on the response of the utility tunnel and its internal pipes. It was found that as the PGA increases from 0.1 to 0.4 g, both peak acceleration and strain of the utility tunnel and its internal pipes increase. The peak acceleration of the utility tunnel and pipes initially decreases and then increases with the angle of incidence, while the strain increases with the angle of incidence, reaching its peak value when the angle of incidence is 30 degrees. The acceleration and strain responses of the utility tunnel and pipe are higher in sand than in clay, with the peak acceleration strongly correlating with the angle of incidence of ground shaking. The findings of this study provide valuable insights into the seismic design of horizontal non-homogeneous field utility tunnel systems.

期刊论文 2025-01-01 DOI: 10.3934/geosci.2025004 ISSN: 2471-2132

As a long lifeline system of buried structures, the utility tunnel (UT) is vulnerable to earthquake invasion. For utility tunnels with inverted siphon arrangements crossing rivers, the seismic response is more complex due to the basin effect of acceleration in the topography and the influence of fluctuating hydrodynamic pressure, but there is currently a gap in targeted seismic response analyses and references. Based on a UT project in Haikou, this paper studied seismic responses of a cast-in-place UT considering the coupled model of water-soil-tunnel structure on ABAQUS software. Herein, the dynamic fluctuation of hydrodynamic pressure is simulated using an acoustic-solid interaction model. A viscoelastic artificial boundary was used to simulate the soil boundary effect, and seismic loads were equivalent to nodal forces. Considering seismic invading direction and varying water elevation, this paper investigates the dynamic response characteristics and damage mechanisms of river-crossing utility tunnels. This study shows that the basin effect causes the soil acceleration around the UT to show variability in different sections, and the amplification factor of the peak acceleration at the central location is almost doubled. The damage and dynamic water pressure of the UT are intensified under bidirectional seismic excitation, and the damage location is concentrated at the junction of the horizontal and the vertical section. Bending moments and axial forces are the main mechanical behaviors along the axial direction. Changes in river levels have a certain positive effect on the UT peak MISES, DAMAGEC, and SDEG, and it exhibits a certain degree of energy dissipation and seismic damping effect. For the aseismic design of cross-river cast-in-place utility tunnels, bidirectional seismic calculations should be performed, and the influence of river hydrodynamic pressure should not be neglected.

期刊论文 2024-11-01 DOI: 10.3390/buildings14113434

The rapid development of underground utility tunnels has led to the formation of a large number of interchange utility tunnels. Due to significant differences in the lateral resisting stiffness in orthogonal directions, coupled with the close relationship between soil deformation and the depth of the utility tunnel, the seismic response mechanism of the interchange utility tunnel is complex. This paper proposes a method for transverse seismic analysis of the underground interchange utility tunnel based on the response displacement method. A load- structure analysis model of a certain underground cross-type interchange utility tunnel is first established. Then, the different conditions corresponding to maximum relative deformation between layers of the interchange node are discussed, and the proposed method is validated via the time-history analysis method. Based on the proposed analysis method in this paper, seismic response analysis is performed on the interchange utility tunnel considering the condition of vertical incidence of three different input seismic waves. Discussions are conducted in terms of internal forces, inter-story displacement angles, and damage responses under seismic excitations in different principal axis directions. The results show that under major earthquakes, the maximum inter-story displacement angle of the interchange node exceeds the standard limit by up to approximately 184 %, while the tensile damage can reach up to 0.985, significantly surpassing the tensile damage limit. Accordingly, the interchange node is the weakest part of the interchange utility tunnel. There exists deformation inconsistency between the interchange node and standard segments due to significant stiffness differences, with the influence range of the interchange node on internal forces, inter-story displacement angles, joint deformations and damage of the utility tunnel is approximately 7, 6, 8, and 6 prefabricated standard segments, respectively. Since the maximum relative deformation between layers of the interchange node does not occur simultaneously, for double-layered and multi-layered interchange utility tunnels, it is necessary to comprehensively consider the maximum inter-story displacement angle between each layer to determine their most unfavorable condition. The analytical method and related research conclusions presented in this paper can provide references for the transverse seismic design of interchange utility tunnels.

期刊论文 2024-10-01 DOI: 10.1016/j.istruc.2024.107112 ISSN: 2352-0124

Excavation of foundation pits can cause deformation and differential settlement to nearby pipe gallery structures, potentially resulting in significant issues such as seepage and structural damage. Based on a deep foundation pit construction project for a residential building plot adjacent to the Wuhan-Jiujiang utility tunnel, a three-dimensional finite element analysis model with cement-soil mixed wall (SMW) and trench cutting remixing deep wall (TRD)-drilled pile is established to study the impact of the excavation process on the utility tunnel. The results indicate that as the foundation pit excavation depth increases, the lateral deformation of the drilled pile support structure shows an initial increase followed by a subsequent decrease, and the maximum lateral deformation occurs at the point approximately one-third from the bottom of the foundation pit. Besides, the surface settlement exhibits an initial increase, followed by a subsequent decrease and eventual stabilization. The deformation of the utility tunnel structure causing by excavation is always within specified limit of 15 mm. Compared to the structure before excavation, the maximum values of axial force, shear force, and bending moment of the utility tunnel increases by 0.09%, 0.14%, and 4.88%, respectively. The stress variation is small, which satisfies the safety requirements for its usage, the feasibility of the TRD-drilled pile support structure is demonstrated. This study can serve as a reference for safety assessment of comparable engineering projects.

期刊论文 2024-08-01 DOI: 10.1061/PPSCFX.SCENG-1395 ISSN: 1084-0680

A buried utility tunnel can effectively protect internal pipes by preventing or mitigating corrosion, external damage, and facilitating maintenance. During an earthquake, the energy from seismic waves is transmitted through the soil to the utility tunnel, then to the support structure, and ultimately to the pipe, making the support's interaction with the pipe crucial. In this study, scaled utility tunnel system undergoes shaking table tests at a horizontally non-homogeneous site. Various supports within the tunnel are modeled dynamic elements to assess energy dissipation. The attenuated seismic waves are then applied directly to the pipe to evaluate its response and validate the results against the tests. The study reveals that greater sliding between the tunnel and pipe leads to more energy dissipation and reduces the likelihood of significant pipe deformation. Situations with increased sliding of the side-wall angle steel support exhibit smaller strain peaks. Longitudinal sliding becomes more pronounced only when peak ground acceleration exceeds 0.8 g in longitudinal loading. The transverse sliding response under longitudinal loading is not influenced by the input acceleration peak. Additionally, modeling the internal pipe's interaction with the support as a simplified dynamic element yields more accurate responses, offering a foundational calculation for the design of shock absorption and vibration isolation in utility tunnel supports.

期刊论文 2024-08-01 DOI: 10.1007/s10706-024-02824-2 ISSN: 0960-3182
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