The mechanisms of tunnelling-induced ground movements are important for risk assessments of tunnelling beneath masonry buildings with shallow foundations, including ground collapse disasters. This paper presents results from five geotechnical centrifuge tests to investigate tunnelling-induced ground movements under the influence of the relative position between the tunnel and a masonry building in plain strain conditions. The tunnel eccentricity-to-building length ratio (e/L) ranges from 0 (tunnel directly below building centre) to 1/2 (tunnel directly below building edge). An advanced coupled centrifuge-numerical modelling (CCNM) method was employed, where the soil, tunnel, and strip foundation are represented in the experimental domain, and the masonry building is modelled in a numerical simulation running in parallel, with key vertical displacements/loads transferred between the domains at the shared boundary (i.e. beneath the building and above the strip foundation). The CCNM approach highlights the significance of building load redistribution on the ground response during centrifuge testing. Results demonstrate that surface and subsurface ground movements in tunnelling scenarios are altered by nearby building positions. It presents the changes in soil vertical and horizontal displacements, key parameters of settlement troughs, soil volume loss, and engineering shear and volumetric strains of the soil. This study provides insights into the mechanisms of tunnelling-induced ground movements under the influence of nearby buildings and serves as an important reference for risk assessments of the construction of new tunnels as well as for numerical and theoretical studies.

Türkey is located in a seismically active region where the Anatolia, Africa, and Arabia tectonic plates converge. The high seismic hazard causes the region to be repeatedly struck by major earthquakes. On February 06, 2023, a devastating Mw 7.7 earthquake struck Türkey at 04:17 a.m. local time (01:17 UTC). Around 9 ​h later at 10:24 a.m. local time, another destructive Mw 7.6 earthquake struck at a distance of 95 ​km towards the north of the first earthquake (www.tadas.afad.gov.tr). The strong ground motion from the Mw 7.7 event shows peak ground accelerations exceeding 1 ​g in the near-field region and affected 11 cities. The effect of the complex fault geometry on the observed high PGAs needs to be examined to understand the associated structural damage. The present study investigates the key characteristics of strong ground motions recorded from 40 stations located in the vicinity of 100 ​km which are commonly used intensity parameters for vulnerability and risk analysis. The complex interaction between fault segments significantly influenced the overall rupture process and the distribution of ground shaking and generated significant pulse-like ground motions in the near-fault region. These ground motions exhibited directivity effects, characterized by pulse-like velocities, high peak ground accelerations, and spectral accelerations. The response spectra are derived for ground motions from several stations for the present destructive/major earthquake and are observed to exceed code prescribed spectra corresponding to the 475-year and 2475-year return periods.

The evolution law of mechanical properties and damage characteristics of early-age flexible formwork filling concrete have a decisive influence on the stability control of surrounding rock of large deformation roadway. This study obtained the mechanical evolution characteristics of flexible formwork concrete filling body by using the standard ratio of engineering site and laboratory system test, clarified the time-space coupling mechanism of acoustic emission characteristic parameters and stress field evolution in the process of damage accumulation, and established a multi-parameter damage constitutive model of early-age concrete considering aging characteristics in combining with the theory of damage mechanics. The results show that: (1) Under the same curing age, the compressive strength of the filling body is significantly negatively correlated with the water-cement ratio, and the correlation decreases with the increase of the curing age, showing obvious strain softening behavior in the post-peak stage; (2) During the loading process, the concrete filling body presents a typical’ three-stage’ acoustic emission response characteristics, that is, the rising period of the initial micro-fracture accumulation, the active period of the main fracture development and the attenuation period after the failure; (3) At a certain curing age, with the increase of water-cement ratio, the total number of acoustic emission b-value signal points generated by the specimen during the test gradually decreases, and the b-value curve changes, and the minimum value appears near the peak stress point; and (4) The pre-peak and post-peak complete damage constitutive equations are established, which can accurately predict the mechanical response of concrete backfill under different curing times and water-cement ratios. The research results provide a basis for selecting the support time and support parameters for large deformation roadway.

Nondestructive sensing technologies are essential for assessing the condition and structural integrity of concrete linings and their surrounding rock. This study utilized ground-penetrating radar (GPR SIR-3000) to detect defects, specifically a dry sand-filled void embedded within a concrete lining. Recognizing that accurate characterization of GPR signals is crucial for understanding the interface between concrete linings and rock mass, the researchers employed the finite-difference time-domain (FDTD) method to simulate electromagnetic wave propagation through concrete models. This approach allowed them to investigate defects in the form of internal thin layers or voids within concrete structures. By combining experimental measurements with forward simulations, the study focused on determining defect thickness using the amplitude ratio method, which enhances measurement accuracy. The experimental findings were found to be consistent with the simulation predictions. Further signal processing techniques, including time delay analysis and spectral analysis, were also applied. The results of this research demonstrate the potential of GPR technology for characterizing defects at the interface between concrete linings and rock mass, or within the surrounding rock mass itself, providing valuable insights into defect thickness and the electromagnetic properties of the materials filling these voids.

The change in size (transverse section and longitudinal length) of a tunnel will result in variation in the temporal and spatial distribution characteristics of the tunnel temperature field, particularly in the cold region. Understanding the size effect on the temperature field is crucial for the prevention of freeze-thaw disasters in large tunnels in high-altitude frozen soil areas. This study investigates the distribution of the tunnel temperature field, considering traffic wind through numerical simulations. The research explores how changes in size affect both the temporal and spatial distribution of tunnel temperatures and freeze-thaw depths. The findings reveal that traffic wind significantly influences tunnel temperature fields, with larger amplitudes observed when accounting for traffic wind compared to no-traffic wind conditions. Additionally, peak temperature of surrounding rock decreases logarithmically with increasing tunnel diameter and depth, while freeze-thaw depth decreases logarithmically with increased section size. Furthermore, the peak temperature of surrounding rock and the freeze-thaw depth are inversely proportional to the tunnel length. Based on these observations regarding section size and length's impact on temperature fields, a mathematical relationship between freeze-thaw depth within surrounding rock and tunnel dimensions is established to elucidate the size effect on temperature fields. These research results could provide theoretical guidance for the design, construction, and disaster prevention of tunnels in alpine regions.

Rockbursts have become one of the most serious disasters in underground engineering around the world, which seriously threaten the construction safety of underground engineering. The effective prediction of rockbursts is of great significance for the safe production management of deep engineering. In this study, the uniaxial compression tests were carried out on sandstone and granite specimens with different shapes and sizes. A multi-index fuzzy comprehensive evaluation model was established based on the acoustic emission (AE) characteristic parameters to quantitatively evaluate the possibility of rock failure. In the fuzzy comprehensive evaluation model, the exponential distribution function in reliability theory was introduced, and the membership function was constructed by Gaussian distribution. The analytic hierarchy process (AHP) and entropy weight method (EWM) were utilized to determine the subjective and objective weights of each index respectively, and the distance function was employed to obtain the synthesized weight. Thereafter, the comprehensive prediction results were obtained by variable fuzzy pattern recognition (VFPR). The results show that for both sandstone and granite specimens with different shapes and sizes, the time advance (Δt) of rock failure forecasting is in the range of 145-491 ​s, and the forecasting point is 0.761-0.889 of the total loading time of rock failure. The prediction results are mainly affected by lithology, while the impact of rock shape and size is relatively insignificant. The sensitivity of fuzzy comprehensive evaluation index is: granite ​> ​sandstone. This research can provide a useful reference for the prediction of rockburst.