Explore the vast range of titles available.

To make efficient use of land resources and minimize the seismic destruction of structures in the ground fissures zone, the shaking table tests and 3-dimensional numerical calculation of the soil were completed, based on the ground fissures site in Xi’an (Class II, with the shear wave velocity Vs ranging from 250 m/s to 500 m/s). Influence laws of ground motion characteristics and geological structure characteristics on seismic response spectra were revealed. Based on the statistics and analysis of seismic waves of the ground fissures site, standardized design response spectra and mathematical formula of the ground fissures site were determined. The findings indicated that: the ground fissure exerted an amplifying influence on seismic waves and changed their spectral characteristics. Moreover, the amplification effect increased with the increasing of the dip angle of ground fissure. These amplified seismic excitations heightened the response of the superstructure, with more pronounced effects observed on the hanging wall compared to the footwall, showing “hanging-wall/footwall effect”. Besides, the structural response was related to the spectral characteristics of seismic waves. Bedrock waves with rich high-frequency components were more likely to resonate with SDOF systems with short period, while Jiangyou waves and El Centro waves with more low-frequency components had more intense resonance responses. With the increasing of fault distance, the characteristic period T g increased, but platform value of response spectra β max decreased. The value of β max was between 2.52 and 3.62. The distributed patterns were respectively ∨-shaped and ∧-shaped. The research results of the design spectra can be used in the seismic design of the superstructure in the ground fissures site.

The ancient city of Xi’an, China, has been suffering severe land subsidence and ground fissure hazards since the 1960s, mainly due to the over-withdrawal of groundwater and large-scale urban construction. This has threatened and will continue to threaten the stability of urban infrastructure, such as the construction and operation of high buildings and subway lines. It is necessary to map the spatiotemporal variations of land subsidence over Xi’an, and to analyze their causes and the correlation with underground water level changes and ground fissure deformation. Time series of land subsidence were observed with the interferometric synthetic aperture radar (InSAR) technique, using multi-sensor SAR datasets from 2012 to 2018. Four land subsidence rate maps over Xi’an city were retrieved from TerraSAR-X, ALOS/PALSAR2, and Sentinel-1 data, each with different tracks. The InSAR derived results were then cross-validated with three independent SAR data stacks, and calibrated with GPS and leveling observations. Next, the spatiotemporal evolutions of three main regional land subsidence zones were quantitatively analyzed in detail, and the surface deformation of the Xi’an subway network was spatially analyzed. Third, the correlations between land subsidence and ground water withdrawal, ground fissure deformation, landforms, and faults were intensively analyzed. Finally, a flat lying sill model with distributed contractions was implemented to model the InSAR deformation over one typical subsidence zone, which further suggested that the ground deformation was mainly caused by groundwater withdrawal. This systematic research can provide sound evidence to serve decision-making for land subsidence mitigation in Xi’an, and may also guide land subsidence research in other cities.

The ground fissures caused by coal mining have seriously affected the ecological environment of the land. Timely and accurate identification and landfill treatment of ground fissures can avoid secondary geological disasters in coal mine areas. At present, the fissure identification methods based on deep learning show excellent performance on roads and walls, etc. Nevertheless, the automatic and reliable segmentation of ground fissures in remote sensing images poses a challenge for deep learning networks, due to the diverse and complex texture information included in the mining ground fissures and background. To overcome these challenges, we propose an improved YOLOv8 instance segmentation network to automatically and efficiently segment the ground fissures in coal mining areas. In detail, a model called FS_YOLOv8 is proposed. The DSPP (Dynamic Snake convolutional Pyramid Pooling) module is incorporated into the FS_YOLOv8 model to establish a multi-scale dynamic snake convolution feature aggregation structure. This module replaces the conventional convolution found in the SPPF module of YOLOv8 and aims to enhance the model's ability to extract features related to fissures with tubular structures. Furthermore, the D-LKA (Deformable Large Kernel Attention) module is employed to autonomously collect fissure context information. To enhance the detection capability of challenging samples in remote sensing images with intricate background and fissure texture, we employ a Slide Loss function. Ultimately, the ground fissure dataset of unmanned aerial vehicle (UAV) images in coal mine areas is subjected to experimental analysis. The experimental findings demonstrate that FS_YOLOv8 exhibits exceptional proficiency in segmenting ground fissures within intricate and expansive mining areas.

The Linfen–Yuncheng Basin is located on the southern edge of the Fenwei Fault Zone, influenced by intense tectonic activity, thick Quaternary sedimentation, and anthropogenic disturbance, it exhibits prominent characteristics of ground subsidence and fissure development. However, uncertainties still exist regarding the primary controlling factors of subsidence. This study employs multi-temporal InSAR data, combined with small baseline subset (SBAS–InSAR) technology to invert the high-precision ground line of sight deformation fields, and conducts time-series decomposition analysis using the Seasonal Trend Decomposition (STL) method. The results show that from 2017 to 2025, subsidence was mainly concentrated in the central and southern regions of the basin, with a maximum cumulative subsidence exceeding 200 mm and an average annual subsidence rate of −40 mm/year. Its spatial distribution is highly consistent with major structural zones such as the Zhongtiao Mountain Front Fault and the Linyi Fault, indicating that fault activity exerts a significant controlling effect on subsidence patterns. Groundwater level fluctuations are positively correlated with overall ground subsidence, and the response rate of different monitoring points is constrained by differences in aquifer depth and permeability. Groundwater aquifer points exhibit rapid and reversible subsidence response, while confined aquifer points are affected by low-permeability or compressible layers, showing a significant lag effect. The research results indicate that time-series analysis based on InSAR can not only effectively reveal the subsidence evolution process at different scales, but also provide a scientific basis for groundwater resource regulation, geological disaster prevention and control, and sustainable regional land utilization.

In this study, the Beibu earth fissure site in the northeastern part of Weihe Basin, which contains four nearly parallel earth fissures, was studied. A long straight microtremor measuring line, containing 49 measuring points across four earth fissures, was established to investigate the dynamic response of this site using Fourier spectrum, response acceleration spectrum, Arias intensity, and HVSR analyses. The main results are as follows: (1) The fundamental frequencies of 44 measuring points obtained from HVSR analysis are concentrated within 1.67 Hz–2.25 Hz, and the existence of the earth fissures has little effect on the fundamental frequency changes. (2) There is an amplification effect near a single earth fissure. The dynamic responses are large at the measuring points near the earth fissure, and the values decrease with increasing distance from the earth fissure. In areas between two adjacent earth fissures, these values decrease and are even lower than those in sites without amplification effects. (3) In this earth fissure site, the general area (or less affected area) and affected areas were delineated based on the amplification effect. In engineering applications, construction design should avoid these affected areas and existing structures should be reinforced to satisfy the seismic fortification requirements.

Evidence of a mine-water impact on groundwater in the karst aquifer downstream of the actively draining West Rand Goldfield can be traced back to the early 1980s. This is attributed to the dewatering of ‘fissure water’ encountered during mining, and its discharge into the Bloubank Spruit catchment. Rewatering of the subsurface void following the cessation of mining in the late 1990s culminated in mine-water issuing from various point sources (shafts and boreholes) in 2002. The past 6 hydrological years have periodically produced the greatest volume and worst quality of mine-water discharge, causing widespread concern for the receiving aquatic environment. In this regard, the proximal Cradle of Humankind World Heritage Site attracts a much sharper focus than the distal, regionally important Hartbeespoort Dam. Objectivity requires that an assessment of the mine-water impact on the receiving surface water resources must recognise both the subregional and regional scales. The evaluation presented in this communication examines the temporal mine-water impact at both scales, and interprets the results in terms of the influence exerted by the natural hydrosystem in mitigating adverse impacts on the water resources environment. An analysis of the respective contributions of each of the major drainages to the quantity and quality of water impounded in Hartbeespoort Dam indicates that the median total dissolved solids (TDS) load delivered by the Bloubank Spruit system amounted to ~26 kt/a in the past 6 hydrological years. This is ~12% of the regional median total of ~224 kt/a entering the impoundment in the same period. By comparison, the preceding long-term record dating back 30 years to 1979 reflects a 66% lower median annual contribution of 8.6 kt, representing ~10% of a regional median total of ~89 kt/a. Proportionally, therefore, the recent 6-year period of high volume and poor-quality discharge from the Bloubank Spruit catchment represents only a marginally greater TDS load contribution to Hartbeespoort Dam than that which characterises the previous 30 years.