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On May 12, 2008, a strong earthquake with a magnitude of 8.0 (Ms) struck Wenchuan town, in the eastern Sichuan area of west
China. Following the earthquake on May 18, the Southwest Jiaotong University organized a damage survey team and dispatched
it to the affected area for the investigation into the damage and collection of information and data. T...
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... Underground structures have been considered to have good performance in seismic scenarios. However, several earthquakes have caused serious damage to tunnels, such as the 1985 Mexico City earthquake in Mexico (Anderson et al., 1986), the 1995 Kobe earthquake in Japan (Suzuki et al., 1996), and the 2008 Wenchuan earthquake in China (Wang et al., 2009), making the seismic safety of tunnels a major public concern. ...
The tunnel crossing soil-rock strata is a common scenario in engineering construction, and it is more vulnerable to earthquake impact than that in uniform ground conditions, while related studies on this topic are scarce. This paper investigates the seismic characteristics of a segmental tunnel crossing soil-rock interface by 1g shaking table test. Regarding the ground-tunnel relative stiffness as a dominant parameter, materials of model soil and model rock are selected. A refined model tunnel is designed to reproduce the segmental feature of the prototype tunnel. An artificial earthquake wave is input from the shaking table along the transverse direction. Seismic performances of the model tunnel, including the acceleration, sectional deformation and longitudinal joint extension, are analyzed to evaluate the soil-structure interaction (SSI). The discrepant seismic responses of the tunnel portions in the two different strata are revealed by the acceleration data. Due to the spatial variation caused by the soil-rock ground condition, significant joint extension near the interface and large sectional deformation at the soil deposit are observed, while deformations of the tunnel portion in rock are negligible. This work presents part of the test data, and it could be used to verify the numerical model, which is aimed at analyzing the seismic performance of the very same segmental tunnel in soil-rock strata.
... Underground structures suffer damage or even collapse not only in the site of soft soil, but within the strata of the rock mass during strong earthquakes. The investigated damage of mountain tunnels after the 1999 Chi-Chi earthquake [1] and the 2008 Wenchuan earthquake [2][3][4][5] have attracted the attention of practitioners and academics. Surveying the underground powerhouses after Wenchuan earthquake revealed a large area of cracking and spalling [6]. ...
A jointed rock mass (JRM) is the usual case in practical engineering, which has significant effects on its mechanical performance. To clarify the difference in the seismic responses of underground structures in JRM sites or homogeneous rock mass (HRM) sites, two models were prepared to take shaking table tests in a structural laboratory. The HRM site was prepared following the similitude relations of material; meanwhile, underground structures of a metro station were embedded during the casting of the models. The JRM site and structure were made with the same material but produced random joints after the natural drying process. Different frequencies of harmonics were used to excite along the two models in the transverse or the longitudinal direction, respectively. The dynamic effect was evaluated by time-frequency and frequency-domain analyses. The test results compared with the HRM model indicated that the JRM model had a 22% reduction in the transverse fundamental frequency, but the dynamic response of the ground surface was enhanced due to the effect of the joints. Under harmonic excitations of the same intensity, the JRM model produced a greater energy response to the station structure and reduced the acceleration response of the platform in the high-frequency region. Meanwhile, the JRM model produced a peak tensile strain at the connections of the main and subsidiary structures that was 31% larger than that of the HRM model, and the range of tensile strains observed at the platform connecting the horizontal passage was 1.5 times larger than that of the HRM model.
... For example, the Great Hanshin earthquake in 1995 caused the complete destruction of more than 30 columns in the Daikai subway station in Kobe City, resulting in the collapse of and damage to the overall structure [3]. In addition, the Wenchuan earthquake and the Chi-Chi earthquake caused damage to numerous urban underground structures and mountain tunnels [4,5]. In response to the complete collapse of the Daikai subway station in the Great Hanshin earthquake, scholars around the world have carried out research work from theoretical analysis, model tests, and numerical simulations [6][7][8][9][10]. ...
The behavior of center columns in shallow-buried underground subway station structures resembles that of high-rise buildings. In both cases, these columns experience significant vertical loads during earthquake events and are susceptible to brittle failure due to inadequate deformation capacity. In this study, the design concept of split columns, commonly employed in high-rise structures, is adapted for application in a two-story, two-span subway station. Initially, a comparative analysis was conducted using quasi-static pushover analysis to assess the horizontal deformation characteristics of traditional and split columns under high axial loads. Subsequently, a comprehensive quasi-static pushover analysis model encompassing the soil–structure interaction was formulated. This model was employed to investigate differences in seismic performance between traditional and innovative underground structures, considering internal forces, deformation capacity, and plastic damage of crucial elements. The analysis results demonstrate that the incorporation of split columns in a two-story, two-span subway station enhances the overall seismic performance of the structure. This enhancement arises from the fact that split columns mitigate excessive shear forces while effectively utilizing their vertical support and horizontal deformation capacities.
... Noteworthy examples of earthquake-induced damage to typical underground civil defense structures include the Tangshan earthquake in China in 1976 (Yu, 2001), the extensive destruction of underground facilities like subway stations, shopping malls, and pipelines in Japan in 1995 (Iida et al., 1996), and the damage to numerous tunnels, particularly those close to the epicenter, during the Sichuan earthquake in China in 2008 (Li, 2008;Wang et al., 2009). These cases vividly illustrate the potential for severe damage or even collapse of underground civil defense structures when subjected to powerful earthquakes, leading to significant economic losses and casualties that ultimately impact social stability and national security (Wang et al., 2001). ...
... Since underground infrastructures can suffer significant damage during severe earthquakes, it is necessary to evaluate their post-seismic performance to minimize the impact of seismic events on such systems. This is a particularly challenging task that requires a fully multidisciplinary approach that takes into account geological, stratigraphic, petrologic, petrophysics, geomechanics and seismotectonic aspects (Hashash et al., 2001;Wang et al., 2009). ...
The strong 1980 M6.81 Irpinia earthquake in Southern Italy critically damaged the Pavoncelli hydraulic tunnel. Based on geological, petrophysical and geomechanical investigations and seismological data, a multi-scale geological model was inferred. The detrital mode and key petrophysical properties (porosity, permeability, and nanopore volumes) data have been used for defining the water-reservoir potential of the arenitic successions, with a focus on defining the hydrogeological model. The model was then used to perform a novel back-analysis of the spatial distribution of the peak ground acceleration (PGA) caused by the 1980 earthquake accounting for site-effects in a robust manner. This analysis, which accounts for site-effects in a robust manner, shows high PGA values along the length of the Pavoncelli tunnel, which is located between the causative fault of the 1980 earthquake in the vicinity of the epicenter. The main outcomes of the study are that: (1) the multi-scale and interdisciplinary approach developed in this study can be used in future studies in this and other areas, (2) the spatial 2D-3D geological model must be accounted for when analyzing distributed systems, (3) the hydrogeological model coupled with porosity data allows for reservoir analyses and (4) the complex tectonic environment in the area hosting the Pavoncelli tunnel plays a strong role in the analysis of the spatial distribution of PGA, creating the need for site-specific seismic microzonation studies and the evaluation of near-fault effects.
... Recent earthquakes, such as the 1999 Chi-Chi, 1999 Kocaeli, and 2008 Wenchuan earthquakes, have caused significant destruction to tunnels despite their higher earthquake resistance than surface buildings [34][35][36][37][38][39][40]. Seismic research indicates that faultcrossing regions are highly seismically active, causing significant damage to tunnels [41][42][43][44][45][46]. Therefore, investigating mitigating strategies is crucial for these areas [47][48][49][50]. ...
The tunnel boring method (TBM) is a widely used and effective tunneling technology in various rock mass quality circumstances. A “faulted rock mass” can range from a highly fractured rock mass to a sheared weak rock mass, making the ground conditions challenging for tunneling, especially for TBMs. “Faulted rock” significantly affects hard rock TBMs, primarily due to the TBM’s high geological risk and poor flexibility. TBMs require careful planning and preparation, starting with preliminary assessments. This study investigates the impact of establishing an isolation material between a circular tunnel and the adjacent faulting rock on seismic response. The two parts of the parametric analysis for the isolation material utilized in the model look at how changes in the mechanical characteristics of the material, such as the shear modulus of the rock and the fault, affect the stresses created in the tunnel. The second section examines how changes in the isolation width concerning the fault width affect the stresses and displacements produced in the tunnel. Additionally, the effectiveness of isolating the tunnel during sudden changes in the characteristics of the rock was investigated under seismic loading perpendicular to the tunnel and parallel to the tunnel. The finite element approach was utilized to model the TBM tunnel and the neighboring rock with a fault or sudden change in the rock using Midas/GTS-NX, simulating the interactions between the rock and the tunnel. Time-history analysis using the El Centro earthquake was conducted to calculate the stresses in the tunnels during seismic events. Peak ground accelerations between 0.10 g and 0.30 g were utilized for excitation. A time step of 0.02 s and a length of 10 s for the seismic event were used in the analysis, with traditional grout pea gravel vs. the isolation layer. Comparisons were made between the absolute stresses (the greatest possible values) in the normal tunnel section (Sxx) and those induced in the tunnel with traditional grout and with isolation. Furthermore, the study of vertical displacement was taken into consideration. The seismic isolation method is highly effective in improving the seismic safety of bored tunnels. The results show that the significant values of the ratio between the shear modulus of isolation and the surrounding soil should be between 0.2% and 0.4%. Where parts of the tunnel run through a fault, the effective length of isolation should be between one and two times the fault width. The dynamic behavior of the tunnel with isolation is better than that with traditional grout. Generally, when isolation is used for any length, it reduces the stresses at the area of sudden change. Consequently, engineering assessments from both structural and geotechnical engineering viewpoints are now required for these unique constructions. An underground structure’s safety should be evaluated by the designer to ensure that it can sustain various applied loads, taking into account seismic loads in addition to construction and permanent static loads. Tunnels may be especially vulnerable in areas where the composition of the soil or rock varies.
... Previous studies have shown that these complex geological conditions such as soft-hard stratum junction, fault fracture zone, and other conditions make the structure more susceptible to damage due to large deformation under earthquakes (Zhang et al. 2017;Zhong et al. 2020). The evidence of tunnel damage can be found in Kobe, Chi-Chi, and Wenchuan earthquakes (Hashash et al. 2001;Iida et al. 1996;Wang et al. 2001Wang et al. , 2009. ...
This paper investigates the dynamic responses of bottom karst caves on the shield tunnels under oblique SV waves according to the project of Dalian Metro Line 5. The viscous-spring artificial boundaries are employed and validated to assure the accuracy of seismic input. The characteristics of deformation and stress, damage evolution process and damage state of the tunnel are discussed, such as under different filling conditions of karst caves, incident angles of SV waves, the elastic modulus of grouting materials, and the combination of multiple karst caves. According to the relationship between tensile damage value and crack width, the damage state classification is divided. The results show that the tunnel’s displacement and stress increase and the damage state is from no damage to severe damage with the increasing incident angle. When the incident angle is 30°, the tunnel’s displacement and stress reach to the maximum, and the axial cracks width higher than 0.2 mm appear on the outer surface of the vault and bottom. The filling conditions of the bottom karst caves can influence the tunnel’s circumferential damage. The structural dynamic response does not change significantly when the elastic modulus of the grouting material is greater than 10 GPa. Compared with one single cave, the damage severity of the inner surface under the multiple karst caves with a large clear distance is weakened and tends to be averaged.
... Therefore, underground structures have long been known to have the ability to withstand earthquake excitations. Nevertheless, in recent large earthquakes, such as the 1995 Kobe earthquake (Iida et al., 1996), the 1999 Chi-Chi earthquake (Wang et al., 2001), the 2008 Wenchuan earthquake (Wang et al., 2009) and the 2016 Kumamoto earthquake (Zhang et al., 2018), a large number of underground structures suffer serious structural damage which significantly challenge this traditional opinion. The post-earthquake rehabilitation and reconstruction of underground structures, especially for subway stations located in populated regions, are much more difficult compared with those of aboveground structures. ...
... In 1999, the Chi-Chi earthquake in Taiwan [2] reported that more than 40 tunnels suffered various forms of structural damage, such as concrete spoil, lining cracks, exposure and buckling of steel bars,and road surface deformation. During the Wenchuan earthquake in 2008 [3], 56 nearby tunnels and subway stations suffered different degrees of damage, mainly including tunnels and surrounding rock collapse, tunnel lining cracking and uplift, and entrance landslides. ...
Seismic intensity measure is an significant parameter that affects the accuracy of structural seismic risk assessment, and plays an important role in the performance-based earthquake engineering research framework. Taking a two story, three span, and shallow buried subway station as the research object, a two-dimensional finite element analysis model of soil structure underground in a typical engineering site was established using ANSYS. Ten earthquake records were selected from PEER as input, and the structural seismic fragility analysis method based on incremental dynamic analysis (IDA) method was introduced into the subway station structure. The maximum story drift angle was used as the structural damage index, and three typical seismic intensity measures were selected, the exploration is conducted on the seismic intensity measures applicable to shallow buried subway stations and the variation pattern of seismic response of subway stations with increasing seismic amplitude. The seismic fragility curve of shallow buried subway station structures is established to obtain the failure probability of the structure at different seismic intensity levels. The analysis results indicate that for shallow buried subway stations, PGA is the most suitable seismic intensity measure, and the comparison with existing empirical fragility curves shows that the vulnerability analysis method is feasible and can quantitatively provide the failure probability of structures at different performance levels, providing reference for seismic design of underground structures.
... Yashiro et al. (2007) classified the damage patterns into three types: damage to shallow tunnels, damage to tunnels in poor geological conditions, and damage to tunnels by fault slide. Wang et al. (2009b) illustrated eight major patterns of seismic damages: portal failure, longitudinal crack, transverse crack, inclined crack, shear failure of lining, pavement cracks, lining spalling, and groundwater inrush. Li (2012) classified the damage characteristics into six types: opening collapse, portal cracks, damage to the lining and surrounding rock, lining cracks and dislocation, invert damage and uplift, and primary supporting cracks and deformation. ...
