Maximum Vertical Displacement Research Articles

Co-seismic rupture of the 2021, Mw7.4 Maduo earthquake (northern Tibet): Short-cutting of the Kunlun fault big bend

We report detailed field measurements of the 2021, Mw7.4 Maduo earthquake surface rupture south of the Kunlun fault, near the northern boundary of Tibet's Bayan Har block. In the field, the dominantly left-lateral surface rupture length was ∼151 km, along the poorly known Jiangcuo fault, with maximum horizontal and vertical displacements of ∼2.1±0.2 to 2.9±0.2 m (up to 3.6±0.2 m at one site) and ∼1.2±0.2 to 1.8±0.2 m, respectively. The rupture, which propagated bilaterally from a roughly central epicenter, terminated in well-defined, ∼20 km-long horsetail splays, as predicted by Coulomb stress failure, consistent with the very young age of the still growing Jiangcuo fault, which may be trying to bypass the Anyemaqen restraining bend in order to connect directly the Kokoxili and Maqen segments of the main Kunlun fault. 14C dating at one site (Cuoerjiala) implies long return times (≥6500 years) for M7+, Maduo-type earthquakes, in keeping with a slow horizontal slip rate of ∼0.55±0.03 mm/yr and the subdued geomorphic expression of the fault. In the broader Tibetan tectonics framework, the Jiangcuo fault may be better interpreted as a kinematic streamlining of the Kunlun fault bend, rather than a result of diffuse deformation across the Bayan Har terrane.

Dynamic response of pre-disintegrated carbonaceous mudstone embankment under multi-lane vehicle load.

The purpose of this study is to reveal the response of multi Lane pre disintegrated carbonaceous mudstone embankment under vehicle dynamic load. In this paper, the pre-disintegrated carbonaceous mudstone samples whose fractal dimension meets the requirements are obtained through the indoor disintegration test of carbonaceous mudstone. Geotechnical basic tests such as particle analysis experiments, compaction tests, and direct shear tests were carried out on the pre-disintegrated carbonaceous mudstone samples, and the physical and mechanical parameters of the pre-disintegrated carbonaceous mudstone were obtained. On this basis, a two-way 4-lane pre-disintegration carbonaceous mudstone embankment model of the expressway was established by ABAQUS numerical software. Three different working conditions are set up to study the dynamic response of multi-lane pre-disintegrated carbonaceous mudstone embankment under vehicle load. The results show that the stress change trend on the surface of the pre-disintegrated carbonaceous mudstone embankment without vehicles is the same as that on the side with vehicles. Under this condition, the vertical displacement of the pre-disintegrated carbonaceous mudstone embankment surface can be as high as 4.33mm, and the vertical displacement change of the embankment in the 0–0.6s phase is basically the same as the stress amplitude distribution. When a traffic jam occurs on one side, the maximum increase in vertical stress on the surface of the embankment on the normal driving side is about 170 kPa compared to condition one, and the vertical displacement at each depth of the embankment has been significantly increased. When a traffic jam occurs on one side, it can significantly increase the vertical stress on the surface of the pre-disintegrated carbonaceous mudstone embankment in this lane. The middle part of the stress time curve of monitoring points 3 and 4 in working condition three is more stable and significant than in working condition one, and the maximum vertical displacement is increased by about 1.70mm. The research results can reference the stability analysis of carbonaceous mudstone embankments and engineering practice.

Interactive effects of crossing tunnel construction on existing tunnel: Three-dimensional centrifugal test and numerical analyses

To study the influence mechanism of a new crossing tunnel on an existing tunnel, centrifugal tests and three-dimensional numerical analysis were performed considering the different excavation sequences of the new tunnel, formation loss, and the clearance between the old and new tunnels. The results indicate that a vertical stretching phenomenon occurs in the existing tunnel, regardless of the sequence in which new tunnel crosses it (above or below). Compared to the new tunnel excavation above the existing tunnel, the manner of under-pass has a more significant impact on the additional internal force and deformation of the existing tunnel. The maximum vertical displacement and longitudinal bending moment typically occur at the symmetry plane at the center. An increase in the clearance between the old and new tunnels leads to an increase in the minimum vertical stress ratio, which is conducive to the formation of load-bearing arches. However, this leads to an increase in the range of collapsed arch, which decreases the maximum values of the vertical displacement and induced bending moment of the tunnel as well as increases the range of deformation. When the construction of the new tunnel leads to a higher loss of formation, there is a significant increase in minimum vertical stress ratio and a clear reduction in the maximum vertical stress ratio, which cause a more marked structural response from the existing tunnel.

Numerical analysis on collapse performance of post-tensioned concrete frames with post-tensioning BFRP bars under an interior-column-removal scenario

Basalt fiber reinforced polymer (BFRP) bars are ideal substitutes for steel reinforcement due to their excellent mechanical performance, which could avoid energy consumption and carbon dioxide emission during the production of construction steel. Concrete structures reinforced with BFRP bars encounter the collapse risk under an occasional accident, such as losing one or several load-bearing members. To date, little research has been performed on the collapse behavior of post-tensioned concrete frames with bonded post-tensioning BFRP bars. This paper developed finite element (FE) models of frame substructures with post-tensioning BFRP bars to investigate their collapse behavior under an interior-column-removal scenario. Parametric analyses show that arranging post-tensioning BFRP bars at the top and bottom of the frame beams or increasing the post-tensioning BFRP bars at the beam bottom could effectively improve the collapse resistance and deformability of the substructures, with the 96.6% and 51.9% improvement at the most, respectively. Reducing initial effective prestress is helpful to the deformability of the frame beams, resulting in a 56.9% increase in ultimate vertical deformation. A mixed reinforcement of BFRP bars and steel reinforcing rebars in the beams is beneficial in preventing collapse. In most cases, the beams’ flexural mechanism and catenary action are essential in resisting the collapse load. The ratio of the maximum vertical displacement at the failed interior column to the net span of the frame beam varies between 0.051 and 0.1. The calculation model for equivalent dynamic increase factors (DIFs) of collapse load was proposed, which could provide a reference for determining DIFs when static collapse analysis is conducted. The DIFs of collapse load for the substructure models were discussed in the proposed method based on the analytical results, indicating that DIFs approached 2.0 at the initial collapse stage and varied between 1.26 and 1.70 at the final collapse failure.

A vertical coupling dynamic analysis method and engineering application of vehicle–track–substructure based on forced vibration

PurposeThis study aims to propose a vertical coupling dynamic analysis method of vehicle–track–substructure based on forced vibration and use this method to analyze the influence on the dynamic response of track and vehicle caused by local fastener failure.Design/methodology/approachThe track and substructure are decomposed into the rail subsystem and substructure subsystem, in which the rail subsystem is composed of two layers of nodes corresponding to the upper rail and the lower fastener. The rail is treated as a continuous beam with elastic discrete point supports, and spring-damping elements are used to simulate the constraints between rail and fastener. Forced displacement and forced velocity are used to deal with the effect of the substructure on the rail system, while the external load is used to deal with the reverse effect. The fastener failure is simulated with the methods that cancel the forced vibration transmission, namely take no account of the substructure–rail interaction at that position.FindingsThe dynamic characteristics of the infrastructure with local diseases can be accurately calculated by using the proposed method. Local fastener failure will slightly affect the vibration of substructure and carbody, but it will significantly intensify the vibration response between wheel and rail. The maximum vertical displacement and the maximum vertical vibration acceleration of rail is 2.94 times and 2.97 times the normal value, respectively, under the train speed of 350 km·h−1. At the same time, the maximum wheel–rail force and wheel load reduction rate increase by 22.0 and 50.2%, respectively, from the normal value.Originality/valueThis method can better reveal the local vibration conditions of the rail and easily simulate the influence of various defects on the dynamic response of the coupling system.

Localization and characterization of the southern Ulsan fault (UF) using geo-electrical imaging: Implication for seismic hazard assessment in an urbanized area

In seismic hazard assessment, subsurface geophysical surveying has gained popularity in recent years towards fault mapping and determining seismic deformation parameters such as fault offset, recurrence, and depth of fault, locating proper trench sites based on the subsurface information. In the present study, electrical resistivity tomography (ERT) was used to (1) locate the trace of the southern segment of the Ulsan fault, (2) to test the applicability of ERT techniques for active fault mapping in a close to the highly urbanized and complex geological environment with a slow tectonic activity. We have applied the ERT technique at five sites. At one place, we used the Wenner array, Schlumberger array, Dipole-Dipole array, and Seismic-profiling techniques to know which method provides a better result in complex geological conditions like Korea. Out of these methods, the Dipole-Dipole array provided high-resolution results and was used for the other two sites. The ERT result shows high and low resistivity zones interpreted as bedrock (mainly Tertiary and Cretaceous formations) and coarse fluvial sediment layer, respectively. The maximum vertical displacement recorded along the fault varies from 6 m to 12 m. Based on the ERT results, two trenches were excavated to directly investigate the deformation pattern associated with the southern segment of the Ulsan fault. The ERT and trench survey results support that the southern Ulsan fault has slipped multiple times since Quaternary. Using this multi-approach, ~5 km long active fault map was prepared for the southern Ulsan Fault. It is found from this study that the integrated approach is highly beneficial where contrasting sub-lithological units exist in terms of their physical properties, even though human activity or the ongoing urbanization process has modified the surface morphology. This study argues for judicious use of ERT techniques to delineate the shallow subsurface geology across various active faults in the Korean peninsula and similar tectonic settings.

Central Load-Bearing Control in the Construction Process of the Concrete Spherical Joint Nandu River Swing Bridge: A Case Study

The rotating mechanism is a significant procedure in swing bridges. In this paper, the Nandu River swing bridge is taken as an engineering case study to exhibit the critical technology of the monitoring process and the construction method of the swing bridge. The research focuses on the central load-bearing control system used to guarantee the security of the construction process. The mechanical problems during the construction process are discussed. Simultaneously, the cable tension and gravity center test are introduced. The non-Hertz contact theory is utilized to calculate the stress distribution of the spherical joint. Furthermore, the overturning moment is computed to monitor the stability of the rotating system based on the stress distribution calculation of the spherical joint. The monitoring process of central load-bearing control is entirely exhibited and discussed. Concurrently, the calculating result of the real-time overturning moment reflects the stability of the rotating construction process, and adjustments are made to ensure the safety of construction. The results show that, during the cable tension process, the middle position of the main arch exhibited 162.3 mm maximum vertical displacement. Meanwhile, the fraction moment was greatly larger than the unbalanced moment. Furthermore, the maximum overturning moment value was 2094.38 kN·m, which was smaller than the resistance of the overturning moment. The present research demonstrates that the non-Hertz contact theory fits the calculation of spherical joint stress distribution. Simultaneously, the middle position of the main arch should be monitored to control the vertical displacement at the cable tensioning stages. The gravity center test and stability control of the rotating construction are the key steps to reaching central load-bearing control.

Frost heave and thawing settlement of the ground after using a freeze-sealing pipe-roof method in the construction of the Gongbei Tunnel

The port section of the Gongbei Tunnel of the Hong Kong Zhuhai Macao Bridge is constructed by the freeze-sealing pipe-roof method, a new construction method that combines the pipe-roof and artificial ground freezing techniques. If the frost heave and thaw settlement of the ground are not effectively predicted and controlled during tunnel construction, then the surrounding environment of the tunnel will be adversely affected. In this study, thermophysical and mechanical parameters such as frost heave ratio and thawing settlement coefficient are obtained by the laboratory test of frozen-thawed soil. Then, the frost heave and thawing settlement laws of the ground are simulated by the full-coupled analysis method of transient temperature and displacement according to the secondary development technology of the ABAQUS finite element software considering the orthotropic deformation characteristics of frozen soil during the construction of the Gongbei Tunnel. The numerical simulation results show that the maximum vertical frost heave displacement of the stratum is 164.47 mm and the maximum horizontal frost heave displacement of the stratum is 53.80 mm, while the maximum vertical thawing settlement displacement of the stratum is −69.45 mm and the maximum horizontal thawing settlement displacement the stratum is −43.89 mm. Moreover, the error of the maximum vertical frost heave displacement between numerical simulation and field measurement is only 5.89 mm, which shows that the numerical simulation method proposed in this paper has high prediction accuracy.

Visualization of localized deformation of external thermal insulation composite systems during aging

• The deformation at different hygrothermal aging stages is tested. • The localized non-uniformity of displacement and strain field is highly correlated with the initiation and evolution of cracks in the finish layer. • The influence of temperature and rainfall on the crack expansion and contraction and local non-uniform deformation of the finish layer is analyzed. The localized deformation of finish coat materials occurs due to hygrothermal aging under harsh service conditions, which adversely impacts the thermal performance and safety of the external thermal insulation composite systems (ETICS). In this study, digital images of the ETICS finish coat were obtained using an industrial digital camera under artificially generated harsh aging environment. Both local deformation field and strain field as well as the surface crack initiation and evolution process of the ETICS finish coat were assessed by the digital image correlation method. The calculation results revealed that the phenomena associated with the occurrence of a localized non-uniform displacement field and strain field of the ETICS finish coat during aging are very significant especially at the cracks, with obvious regional boundaries. The localization of the strain field is highly correlated with the initiation and evolution of cracks with a significant local distribution band. The maximum horizontal displacement and vertical displacement during the resting phase after being exposed to rain were reduced by 77.14 and 57.69%, respectively compared with those at high temperature. The massive expansion and shrinkage resulted in the cracking of the finish coat. When the cracked finish coat expands at high temperature or shrinks when exposed to rain, the cracks also expand or shrink accordingly, so that the localized non-uniformity level of the displacement field decreases or increases, and the strain on the reference line presents uniform change or sudden change. The non-uniform deformation of the finish coat caused by the cyclic action of aging factors such as high temperature and rainfall eventually becomes more and more significant. The characteristic index for non-uniform deformation was proposed and its evolution laws with the aging time were systematically analyzed. Taken as the next research focus, it can provide a reference for analyzing the deformation and deterioration process of the ETICS and ensuring the operation safety.

Assessing the deformation response of double-track overlapped tunnels using numerical simulation and field monitoring

The unprecedented rate of metro construction has led to a highly complex network of metro lines. Tunnels are being overlapped to an ever-increasing degree. This paper investigates the deformation response of double-track overlapped tunnels in Tianjin, China using finite element analysis (FEA) and field monitoring, considering the attributes of different tunneling forms. With respect to the upper tunneling, the results of the FEA and field monitoring showed that the maximum vertical displacements of the ground surface during the tail passage were 2.06 mm, 2.25 mm and 2.39 mm obtained by the FEA, field monitoring and Peck calculation, respectively; the heaves on the vertical displacement curve were observed at 8 m (1.25 D , where D is the diameter of the tunnel) away from the center of the tunnel and the curve at both sides was asymmetrical. Furthermore, the crown and bottom produce approximately 0.38 mm and 1.26 mm of contraction, respectively. The results of the FEA of the upper and lower sections demonstrated that the tunneling form has an obvious influence on the deformation response of the double-track overlapped tunnel. Compared with the upper tunneling, the lower tunneling exerted significantly less influence on the deformation response, which manifested as a smaller displacement of the strata and deformation of the existing tunnel. The results of this study on overlapped tunnels can provide a reference for similar projects in the future.

The effects of 3-D Screw on the nasomaxillary complex in skeletal class III malocclusion

Aim of the study is to evaluate the Stress distribution and displacement of various structures of nasomaxillary complex with 3- D screw in skeletal class III malocclusion. An analytical model was developed from a human skull of a 15-year-old male. CT scan images of the skull were taken in axial direction parallel to the F-H plane, which was processed using Mimics software, required portion of the skull & 3-D screw appliance was converted into geometric model using reverse engineering technique. ANSYS software was used to solve the mathematical equation. Contour plots of the displacement and stresses were obtained from the results of the analysis performed. Maximum transverse displacement was 3.18mm at the permanent first maxillary teeth. Maximum antero-posterior displacement was 1.26mm at the anterior part of zygomatic bone and 1.35mm of displacement frontozygomatic suture. maximum vertical displacement was 2.81 mm representing the inferior and medial portion of the nasal bone and indicating downward displacement. Pyramidal displacement of maxilla was evident. Apex of pyramid faced towards nasal bone and base was located on the oral side. There was downward, forward movement of maxilla with a tendency toward posterior rotation. Maximum von Mises stresses were found along midpalatal, zygomaticomaxillary, nasomaxillary, frontozygomatic sutures.

Load Deformation Effect of CBD Ground Cluster in Zhengzhou City

With the increase of the number of urban cluster buildings, it is bound to cause land subsidence near cluster buildings. Based on Farrell’s load deformation theory, this paper studies the surface deformation and geoid change caused by Zhengzhou CBD cluster buildings. The results show that the maximum horizontal displacement of the International Convention and Exhibition Center is 0.1 mm, the maximum vertical displacement is 0.33 mm, and the maximum geoid fluctuation is 17.4 mm; the maximum inclination of geoid is 1.89 s. In addition, the influence of independent single buildings on ground deformation is centered on the single building and diffuses outward; the influence of cluster load buildings on the ground deformation of a single building is nonlinear attenuation and superimposed with each other.

Multi-Temporal SAR Interferometry for Vertical Displacement Monitoring from Space of Tengiz Oil Reservoir Using SENTINEL-1 and COSMO-SKYMED Satellite Missions

This study focused on the quantitative assessment of the vertical displacement velocities retrieved using Sentinel-1 and Cosmo-SkyMed synthetic aperture radar images for the Tengiz oilfield. Tengiz oilfield was selected as a study area because of its historically reported continuous subsidence and limited up-to-date studies during recent years. The small baseline subset time-series technique was used for the interferometric processing of radar images acquired for the period of 2018–2020. The geospatial and statistical analyses allowed to determine the existing hotspots of the subsidence processes induced by oil extraction in the study area. Ground deformation measurements derived from the Sentinel-1 and COSMO-SkyMed satellite missions showed that the Tengiz oilfield continuously subsided during 2018–2020 with the maximum annual vertical displacement velocity around −77.4 mm/y and −71.5 mm/y, respectively. The vertical displacement velocities derived from the Sentinel-1 and the COSMO-SkyMed images showed a good statistical relationship with R2≥0.73 and RMSE ≤3.68 mm. The cumulative vertical displacement derived from both satellites for the most subsiding location also showed a good statistical relationship with R2 equal to 0.97 and RMSE = ± 4.69. The observed relative differences of measurements by both satellites were acceptable to determine the ongoing vertical surface displacement processes in the study area. These studies demonstrated a practical novelty for the petroleum industry in terms of the comparative assessment of surface displacement measurements using time-series of medium-resolution Sentinel-1 and high-resolution COSMO-SkyMed radar images.

Three-Dimensional Surface Displacements of the 8 January 2022 Mw6.7 Menyuan Earthquake, China from Sentinel-1 and ALOS-2 SAR Observations

The 8 January 2022 Mw6.7 Menyuan earthquake was generated in the transition zone between the western Lenglongling fault and the eastern Tuolaishan fault, both being part of the Qilian–Haiyuan fault system with an important role in the adjustment of the regional tectonic regime. In this study, four pairs of SAR (synthetic aperture radar) data from Sentinel-1 and ALOS-2 (Advanced Land Observation Satellite-2) satellites were used to derive the surface displacement observations along the satellite line-of-sight (LOS) and azimuth directions using the differential interferometric SAR (InSAR, DInSAR), pixel offset-tracking (POT), multiple aperture InSAR (MAI), and burst overlap InSAR (BOI) methods. An SM-VCE method (i.e., a method for measuring three-dimensional (3D) surface displacements with InSAR based on a strain model and variance component estimation) was employed to combine these derived SAR displacement observations to calculate the 3D co-seismic displacements. Results indicate that the 2022 Menyuan earthquake was dominated by left-lateral slip, and the maximum horizontal and vertical displacements were 1.9 m and 0.6 m, respectively. The relative horizontal surface displacement across the fault was as large as 2–3 m, and the fault-parallel displacement magnitude was larger on the southern side of the fault compared with the northern side. Furthermore, three co-seismic strain invariants were also investigated, revealing that the near-fault area suffered severe deformation, and two obviously expanding and compressed zones were identified. We provide displacements/strains derived in this study in the prevailing geotiff format, which will be useful for the broad community studying this earthquake; in addition, the SM-VCE code used in this study is open to the public so that readers can better understand the method.

Analysis and prediction of the mechanical behavior of corrugated plate as primary support in tunnels with elastoplastic constitution

Compared to the traditional primary support mainly made of shot concrete, new-type corrugated-plate support, which has been maturely used in pipes and culverts, has many advantages like good flexibility and high efficiency. To study its mechanical characteristics in tunnels, several finite-element models with different constitutions, sizes, loads and yield stresses were built and simulated. And for its correctness and utility, a verification experiment and 2 kinds of neural networks were also carried out. The result shows that: firstly, 90% of the result in the simulation is in accord with the experiment. Then, in the elastoplastic model, for vertical displacement, the maximum is at the vault. For Von-Mises stress, the stress is higher at the vault and invert (241 MPa as an example), while it is relatively lower at part of the haunch (7 MPa as an example). Next, in terms of the increase of d (maximum vertical displacement), there are 2 phases: elastic phase and plastic phase. In the former phase, d increases steadily, while in the latter phase it surges rapidly. In terms of s (maximum Von-Mises stress), there are 3 phases: elastic phase, transition phase and plastic phase. In elastic and plastic phase, s ascends normally. But in the transition phase, s increases slowly until all the structure turns plastic. Moreover, as for the bearing capacity, the influence of t is the biggest, followed by h and w. Finally, for prediction, neural networks are a good choice. Meanwhile, different settings are needed for predicting different values. For predicting d, LM (Levenberg-Marquardt) algorithm with appropriate number of neurons is efficient (13 s for each training, MSE (Mean Squared Error) = 2.24). For predicting s, BR (Bayesian Regularization) algorithm is better with enough neurons (120 s for each training, MSE = 0.7). Since the conditions are finite, within an applicable scope, this research provides some innovative suggestions for applying new-type corrugated-plate support and neural networks in tunnelling field.

Particulate Projectiles Driven by Cavitation Bubbles.

The removal of surface-attached particles with cavitation bubbles is usually attributed to the jetting or shear stresses when bubbles collapse. In this Letter, we report an unexpected phenomenon that millimeter-sized spherical particles made of heavy metals (e.g., stainless steel), when initially resting on a fixed rigid substrate, are suddenly accelerated like projectiles through the production of nearby laser-induced cavitation bubbles of similar sizes. We show experimentally and theoretically that the motion of a particle with radius R_{p} is determined by the maximum bubble radius R_{b,max}, the initial distance from the laser focus to the center of the particle L_{0}, and the initial azimuth angle φ_{0}. We identify two dominant regimes for the particle's sudden acceleration, namely, the unsteady liquid inertia dominated regime and the bubble contact dominated regime, determined by R_{b,max}R_{p}/L_{0}^{2}. We find the nondimensional maximum vertical displacement of the particle follows the fourth power and the square power scaling laws for respective regimes, which is consistent with the experimental results. Our findings can be applied to nonintrusive particle manipulation from solid substrates in a liquid.

Aerodynamic loads and bridge responses under train passage: case study of an overpass steel box-girder cable-stayed bridge

Increased train speeds have led to significant train-induced wind problems. This paper describes a numerical study of the aerodynamic loads produced when a train passes under a bridge and the bridge dynamic response based on a steel box-girder cable-stayed bridge. The results indicate that the wind pressure on the bottom plate and the maximum lift on the beam sections increase as the train speed increases or as the clearance under the bridge decreases. Changes in the intersection angle are found to have a greater impact on the 1/4-span and 3/4-span regions. The effects of the various influencing factors are basically the same in the construction and operation stages. As the train speed increases or the clearance under the bridge decreases, the bridge responses exhibit an upward trend. As the intersection angle decreases, the vibration displacement tends to increase, but the effects on the vibration acceleration and maximum counter-force of the temporary pier are not consistent. Compared with the construction stage, the dynamic responses of the main girder are smaller in the operation stage due to the larger overall rigidity and the support constraints. In the parameter ranges investigated in this study, the absolute values of maximum vertical bridge vibration displacement and acceleration decrease from 4 to 16 mm and from 85 to 400 mm/s2, respectively, in the construction stage to 1–5 mm and 42–174 mm/s2 in the operation stage. Moreover, the counter-force falling on the temporary pier after the main girder turns does not exceed the 2000-kN positive force or 300-kN negative force limits. In the operation stage, the bridge vibration responses will not affect the comfort of pedestrians.

Multi-objective optimization-based prediction of excavation-induced tunnel displacement

This paper proposes an inverse method for improving the prediction of tunnel displacements during adjacent excavation. In this framework, staged data assimilation and parameter identification are conducted using the multi-objective particle swarm optimization algorithm. Recent monitoring data are assumed to be more informative and assigned more weights in the multi-objective optimization to improve the prediction accuracy. Then, an empirical formula is applied to correct the time effect of tunnel displacement. The Kriging method is introduced to surrogate the finite element model to reduce computational cost. The proposed framework is verified using a typical staged “excavation nearing tunnel” case. The predictions using the updated parameters are in good agreement with the measurements. The identified values of underlying soil parameters are within the typical ranges for the unloading condition. The updated time effect indicates that tunnel displacements may develop excessively in the three months after the region S1-B is excavated to the bottom. The maximum vertical tunnel displacement may increase from the currently measured 12 mm to the calculated 26 mm if the later construction is suspended long enough. Subsequent constructions need to be timely conducted to restrain the time effect and control tunnel displacements.

Damping characteristics of the architectural coated fabric and its influence on the vibration response of membrane structures

The influence of material damping is ignored in the current membrane structure design. Based on the damping characteristics of coated fabric obtained by the dynamic mechanical analyzer, the applicability of classical Maxwell model, generalized Maxwell model, three-parameter liquid model, fractional derivative Maxwell model, and fractional derivative Kelvin model to describe the viscoelastic properties of coated fabric were discussed. The free-falling body excitation vibration test of plane tensioned membrane structure is carried out and the dynamic response of plane membrane structure under impact load was studied. The reasonable viscoelastic damping constitutive model is obtained through a systematic comparison of the existing models then implemented in Abaqus software and subsequently validated with the data obtained from the vibration test. Taking saddle-shaped and umbrella-shaped membrane structures as research objectives, the dynamic response of membrane structures under dynamic wind load considering material damping performance is discussed. The results show that the damping property of the coated fabric significantly affects the dynamic characteristics of the membrane structure. Due to the existence of material damping, the modal frequency of the overall structure is greater than the result of the elastic model. The reduction factor of maximum vertical displacement can reach 67.14%, and the reduction factor of maximum principal stress can reach 68.93%, which makes the structural design safety factor high.

Collapse Resistance Model and Deformation Mechanism of Shear Wall Replacement

Structural elements can be damaged or defective due to man-made and natural disasters, which will result in structural resistance below the design value. Component replacement can effectively improve the safety of the structure and does not affect its later use. However, this construction process must dismantle defective components. If the process is not properly operated, it will cause progressive collapse of the structure. There are few studies on progressive collapse resistance based on field tests. In this paper, the alternate load path method is used to study the deformation mechanism of reinforced concrete shear wall structures when partial members fail. The maximum vertical displacement and strain of the beam end near the failure walls are obtained, and load transfer laws are analyzed. Based on the component replacement construction of a high-rise shear wall structure, the progressive collapse resistance mechanism of the shear wall structure is verified, which provides theoretical guidance for component replacement construction.