Ground Fissures Research Articles

The origin and impact of the Shizhuang ground fissure, Yingxian area, Datong Basin, China

The Datong Basin is part of the regionally extensive Fenwei Graben System, a major tectonic zone impacted by active tectonics and the resulting damage to life and infrastructure. The basin also contains the Shizhuang ground fissure system. In this study, the likely origin, surface extent, and fissure subsurface characteristics are explored by traditional methods: surveying, mapping, trenching, drilling, and seismic exploration. The Shizhuang ground fissure is located at the intersection of the Xiaoshikou fault and the southern Liuleng margin fault in Yingxian County. It has a length of 2.1 km, excellent continuity, and semi-elliptical surface morphology. The dislocation of strata induced by the fissure increases significantly as the depth increases. The strata bend downward and form typical traction structures near the fissure plane, indicating that the fissure has prominent synsedimentary fault characteristics. The fissure causes serious damage to houses, farmlands, roads, and public facilities, featuring large tensile cracks and vertical dislocations. The resulting data and interpretations indicate that: (1) the ground fissures connect to two major subsurface active faults, which lay the tectonic foundation for the fissure; (2) accelerated groundwater extraction has reactivated the underlying faults and exacerbated fissure development; and (3) mitigation is best achieved by cessation of excessive groundwater pumping, appropriate engineering design, and local avoidance for placement of critical structures. This paper provides a heretofore generally unknown example, promotes research on the mechanisms of fissures, and has guiding significance for disaster prevention and reduction in this area.

Assessment of liquefaction susceptibility in Quaternary deposits: A case study from Jhapa Bazar area, eastern Nepal

Liquefaction is generally experienced in unconsolidated fine- grained sediments during the large earthquakes. In Nepal, the southern part of the country comprises Quaternary deposits called as Indo-Gangetic deposit. Sand and silts are dominant in this zone, where groundwater level is also relatively high. In eastern Nepal, several places have experienced ground fissures, sand boiling, and liquefaction during the large earthquakes in the past history. There are several factors including soil properties, groundwater level, grain size of sediments and ground acceleration that contribute to ground liquefaction. The eastern Nepal faced a devastating earthquake in 1934 (magnitude of 8.4), Udaypur earthquake in 1988 (magnitude of 6.6) and Sikkim-Nepal earthquake in 2011 (magnitude of 6.8) and there is still possibility of similar large earthquakes in future. Liquefaction was reported in many places during Nepal-Bihar earthquake that indicates possibility of liquefaction during similar earthquakes. Liquefaction potential values are calculated from sediment grain size, subsurface geology, groundwater level and standard penetration test (SPT)-N values. The epicenter, magnitude, and other parameters of Nepal-Bihar earthquake have been used to calculate the liquefaction potential. A liquefaction susceptibility map has been prepared in the study area that comprises low, medium, and high liquefaction potential zones. About 20% of the study area including Jhapa Bazar and its surrounding area seems highly susceptible to liquefaction.

Mechanism of Fuping ground fissure in the Weihe Basin of northwest China: fault and rainfall

The special geological conditions of the Weihe Basin, located in the southern Fenwei Graben System, are the cause of many of the ground fissures developing in this area. The Tingzi ground fissure in Fuping County is one of the typical and particular ground fissures found in the Weihe Basin. The ground fissure is famous for its sudden appearance after heavy rainfall. To explore the characteristics and mechanism of the fissure, some geological methods were carried out in the study area for this study, such as surveying, mapping, trenching, drilling, and seismic exploration. The main conclusions are as follows: (1) the fissure is located on the hanging side of the secondary fault of the Liquan–Pucheng–Heyang fault, with a NE40°–NE75° strike and a length of 2.7 km. (2) The fissure is steeply inclined and presents a “funnel” shape in the shallow strata. There are many secondary cracks near the main fissure. (3) The fissure is connected with underlying fault and possesses the characteristics of synsedimentary faults reflecting the historical stages of fissure activities. (4) The fissure destroys farmlands and houses along the fissure, and mainly causes tensile damage. (5) The fissure was controlled by regional extension and fault, and it was promoted and enlarged by rainfall and other influential factors.

Land Subsidence and Ground Fissures in Beijing Capital International Airport (BCIA): Evidence from Quasi-PS InSAR Analysis

Land subsidence is a global environmental geological hazard caused by natural or human activities. The high spatial resolution and continuous time coverage of interferometric synthetic aperture radar (InSAR) time series analysis techniques provide data and a basis for the development of methods for the investigation and evolution mechanism study of regional land subsidence. Beijing, the capital city of China, has suffered from land subsidence for decades since it was first recorded in the 1950s. It was reported that uneven ground subsidence and fractures have seriously affected the normal operation of the Beijing Capital International Airport (BCIA) in recent years before the overhaul of the middle runway in April 2017. In this study, InSAR time series analysis was successfully used to detect the uneven local subsidence and ground fissure activity that has been gradually increasing in BCIA since 2010. A multi-temporal InSAR (MT-InSAR) technique was performed on 63 TerraSAR-X/TanDem-X (TSX/TDX) images acquired between 2010 and 2017, then deformation rate maps and time series for the airport area were generated. Comparisons of deformation rate and displacement time series from InSAR and ground-leveling were carried out in order to evaluate the accuracy of the InSAR-derived measurements. After an integrated analysis of the distribution characteristics of land subsidence, previous research results, and geological data was carried out, we found and located an active ground fissure. Then main cause of the ground fissures was preliminarily discussed. Finally, it can be conducted that InSAR technology can be used to identify and monitor geological processes, such as land subsidence and ground fissure activities, and can provide a scientific approach to better explore and study the cause and formation mechanism of regional subsidence and ground fissures.

Deformation Activity Analysis of a Ground Fissure Based on Instantaneous Total Energy.

This study proposes a novel instantaneous total energy method to perform an activity analysis of ground fissures deformation, which is calculated by integrating the extreme-point symmetric mode decomposition (ESMD) method and kinetic energy based on the time-series displacement acquired by shape acceleration array (SAA) sensors. The proposed method is tested on the Xiwang Road fissure in Beijing, China. First, to fully monitor the hanging wall and footwall of the monitored ground fissure, a 4 m-long SAA in the vertical direction and an 8 m-long SAA in the horizontal direction were embedded in a ground fissure to obtain an accurate time-series displacement with an accuracy of ±1.5 mm/32 m and a displacement acquisition frequency of once an hour. Second, to improve the accuracy of the activity analysis, the ESMD method and Spearman’s rho are applied to perform signal denoising of the original time-series displacement obtained by the SAA sensors. Finally, the instantaneous total energy is obtained to analyze the activity of the monitored ground fissure. The results demonstrate that the proposed method is more reliable to reflect the activity of a monitored ground fissure compared to the time-series displacement.

Monitoring subsurface ground movement using fibre optic inclinometer sensor

The monitoring of subsurface ground movement is important for the prevention and control of geological disaster including land subsidence, ground fissure, surface collapse, and landslides. Inclinometer and extensometer are examples of the conventional geotechnical instruments for monitoring the subsurface ground movement. However, most conventional geotechnical instruments for subsurface monitoring are limited to discrete sensing, high cost, and susceptible to various reading errors. This paper presents the advancement of technology mechanism to monitor horizontal ground movements as well as the data processing technique involved. Distributed optical fibre inclinometer is developed through laboratory pipe bending tests whereas the data is corroborated with conventional instruments. This system was installed on site, measuring the performance of the sensors as well as to monitor the associated ground movements. A simple cost comparative study between fibre optic inclinometer and conventional geotechnical instrumentation indicates the new technology is cost-effective for applications in ground monitoring particularly when monitoring a large number of borehole points and measurement arrays.

Effects of mining speed on the developmental features of mining-induced ground fissures

Shallow coal seam exploitation not only causes serious surface subsidence but also induces extensive ground fissures, which severely threaten the safety of underground mining and the surface eco-environment. We use the Daliuta coal mine of the Shendong mining district in China as a case study to investigate and characterize the influence of underground coal mining on the development of ground fissures. A new comprehensive impact parameter K of geology and mining for ground fissure development is introduced to explain the effects of mining speed on the developmental features of ground fissures. The results show that ground fissures often develop in the surface tensile zone ahead of the working face advancing position and show an inverted C-shape on the surface, which is similar to periodic fracturing of the basic roof. The ground fissure angle increases linearly with mining speed and logarithmically with K, while the developmental cycle decreases linearly with mining speed. We propose a technical measure to control ground fissure disasters by adjusting mining speed, which provides a theoretical reference for eco-environmental governance in shallow coal seam mining districts.

Research on Spatiotemporal Land Deformation (2012–2018) over Xi’an, China, with Multi-Sensor SAR Datasets

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.

Study and application of sequential extraction method of ground fissures based on object

Study and application of sequential extraction method of ground fissures based on object

Study on Tensile Strength and Tensile-Shear Coupling Mechanism of Loess around Lanzhou and Yanan City in China by Unconfined Penetration Test

Tensile strength is an important but seldom noticed parameter that reveals the constitutive relations of soil. For the loess, the tensile strength can be used to explain earthwork-induced damages such as tension cracks in cut slopes and corresponding slope failures, or natural disasters such as ground fissures. The present study chose an indirect method, particularly the unconfined penetration (UP) test, to measure the tensile strength of remolded loess and undisturbed Q2 and Q3 loess obtained from different districts in China. The results indicated that the tensile strength of the undisturbed loess was primary determined by the void ratio. In addition, multiple correlations were observed between the void ratio and the degree of saturation. The tensile linear stiffness exhibited an exponential increase following an increase in the tensile strength. The mechanism of the tensile-shear coupling strength criterion was proposed. Linear relations between the mechanical parameters were deduced under the tensile-shear coupling condition and were verified by the remolded and undisturbed loess, respectively. Both the unconfined compressive strength and cohesion decreased under the tensile-shear coupling condition. Comparisons with other strength models validated the suitability of the tensile-shear coupling strength criterion for the loess. This study aims to present a more comprehensive understanding on the tensile strength of loess and offer parameter guidance for stability calculations in practical engineering.

Evolution characteristics of spontaneous combustion in three zones of the goaf when using the cutting roof and release pressure technique

AbstractThe changes associated with the cutting roof and release pressure mining method in the three zones that are susceptible to spontaneous combustion in the goaf with “Y” type ventilation system were studied. For the investigated underground coal mine working face, its three zones of spontaneous combustion have a “U” type ventilation system for the traditional mining method and a “Y” type ventilation system for the cutting roof and release pressure mining method. These systems were monitored using a beam tube method, and the evolution characteristics of spontaneous combustion of the three zones was analysed. The monitoring data showed that when using a traditional mining method with a “U” type ventilation system, the scattered tropical zone converts into the oxidation heating zone after 68.5 m in the goaf, and the suffocative zone presents after 85.5 m. For the cutting roof and release pressure mining method together with a “Y” type ventilation system, the scattered tropical zone converts into the oxidation heating zone after 84 m in the goaf, and the suffocative zone appears after 198.8 m. Compared to traditional mining, the width of the oxidation heating zone increases when using the cutting roof and release pressure method. To prevent spontaneous combustion of the goaf, the comprehensive techniques of the pressure balance for fire control, ground fissure sealing, working face sealing, retained roadways guniting and inert gas fire extinguishing have been used in the studied coal mine. The CO concentration of the goaf is less than 300 ppm during the mining process. Safe mining of the tested working face shows that the cutting roof and release pressure technique can be applied to control the coal seam spontaneous combustion.

Overview of ground fissure research in China

Ground fissures in China have garnered increasing international attention in recent years due to their areal extensiveness, large scale, and high hazard potential. These fissures, especially those in the Fen-Wei Basin and North China Plain, severely restrict planning and construction in big cities, threaten the operation of underground and above ground railways, and cause serious economic loss. Recent research shows that ground fissures in China occur mainly in sedimentary basins and develop along active faults and at the edges of groundwater cones of depression. Most of these fissures are caused by the combined action of tectonic stress and hydrodynamic force. Effective ground fissure disaster reduction technologies are developed and they include pumping control, reasonable avoidance, adaption to deformation, and local strengthening. This paper provides an overview on ground fissure studies in China and demonstrates how research results can serve economic development and geohazard mitigation.

Ground deformation and fissure activity in Datong basin, China 2007–2010 revealed by multi-track InSAR

abstarctThe Datong basin is one of the complex geologic environments in China. Several faults are distributed in the basin, and a number of hidden faults have been discovered within the basin. Ground fissures (GFs) and land subsidence occur in this region. In the past, ground subsidence at Datong basin has been studied using groundwater level records, intermittent small-scale levelling measurements and field investigations. However, due to the low spatial resolution and temporal sampling of these records, detailed ground deformation within the basin remains poorly understood. In this study, we exploited Envisat ASAR and ALOS PALSAR images to map the ground deformation between 2007 and 2010. Most of the deformation within the basin occurred at rates of <20 mm/year. In addition to the subsidence due to coal mining in the western mountainous areas, at least four large subsidence zones could be detected. Our analysis indicates that the ground subsidence is affected by groundwater extraction and the distribution of faults. Additionally, the vertical deformation is much larger than the deformation in the east–west direction. Obvious deformation gradients occurred on individual GFs and the activity of the GFs varied spatially. Finally, Interferometric synthetic aperture radar (InSAR) observations related to groundwater exploitation and GFs were modelled and discussed.Abbreviations: GFs: ground fissures; SAR: Synthetic Aperture Radar; ASAR: Advanced Synthetic Aperture Radar; ALOS: Advanced Land Observing Satellite; PALSAR: Phased Array type L-band Synthetic Aperture Radar; InSAR: Interferometric Synthetic Aperture Radar; ESA: European Space Agency; JAXA: Japan Aerospace Exploration Agency; SBAS: Small Baseline Subsets; SRTM: Shuttle Radar Topography Mission; DEM: Digital Elevation Model; DORIS: Dopper Orbitography and Radiopositioning Integrated by Satellite instrument; MCF: minimum cost flow; LOS: line-of-sight2D/3D: two-dimensional/three-dimensional

Activity Characteristics and Safety distance of Gaoliying Ground Fissure in Beijing

In all ground fissures in Beijing, Gaoliying Ground Fissure has characteristics of highly activity, and it cause serious damages on constructoins. With the distribution as well as the development of land subsidence and the change of the groundwater level, a series of work has been conducted to explain the mechanism of the formation of Gaoliying Ground Fissure. For example, field damage investigations and trench observations were used to define the affected distance of ground fissure; three-dimensional deformation was monitored to determine active characteristic of ground fissure. This paper points out that Gaoliying ground fissure is controlled by Huangzhuang-Gaoliying Fault, which mainly moves in the vertical direction. The rapid decrease of the ground water level greatly increases the development of ground fissure. The distance of damaged zones affected by ground fissure in the hanging-wall of the fault reaches 49.5m, and the distance of damaged zones in the footwall of the fault is 17.5 m. A suggested safety distance of type-one and type-two buildings is 100 m. For type-three buildings, the suggested safety distance is 80 m.

Physical Modeling and Numerical Simulation of the Seismic Responses of Metro Tunnel near Active Ground Fissures

Ground fissures pose serious hazards to underground, as well as aboveground, structures. In underground railways, which are near ground fissures, the potential for disasters is even higher since tunnels face threats from fissure activities. To determine the interaction between a tunnel and ground fissure in the event of an earthquake, field surveys and data analysis were applied to study the activity and damage caused by the fissure. Shaking table tests and a numerical simulation model were used to understand the dynamic response of the fissure site and tunnel. The fissure site had a clear hanging wall effect, where the acceleration amplification was larger in the hanging wall than that in the footwall both on the surface and at the middle of the fissure site. The zone of influence was also wider in the hanging wall. The acceleration magnification factor increased with the burial depth and peak acceleration of the input earthquake. The peak ground acceleration (PGA) decreased with the burial depth on both sides of the fissure. The greatest PGA coefficient was obtained at the surface of the site. The vertical soil pressure was influenced by the metro tunnel and fissure. The vertical soil pressure was larger in the hanging wall, especially in the zone near the fissure, but was less near the tunnel. The horizontal soil pressure above the tunnel was less than that near the fissure. The results of this study are essential for the safe design of underground railway systems.

Geo-environmental Quality Evaluation Based on GIS in Shiyan-Wudang Mountain Area

The Shiyan-Wudang Mountain area is located in the Danjiangkou Reservoir Area, the upper reaches of the Han River, the hinterland of the Qinba Mountain Range. The main geological environmental problems in the region include collapse, landslides, debris flow, ground collapses, and ground fissures, which seriously restrict local economic development. Based on the analysis and summary of the distribution, development characteristics, formation conditions and influencing factors of geological disasters in this area, the multiple comparisons is used to select the formation complex, slope, distance from the fault zone, water yield property, distance from surface water system, average annual rainfall, mountain disaster point density, soil erosion, and human engineering activity intensity as the evaluation indicators, the geological environment quality evaluation index system of Shiyan-Wudang Mountain area was established; Geographic information system (GIS) technology is used to carry out hierarchical management of basic maps, and establish a spatial database of geological environment conditions. The analytic hierarchy process is used to determine the weight of the index system. The evaluation module developed by MapGIS platform is used to evaluate the geological environment quality of the study area. Respectively, the area of geological environment with best quality, good, poor and worst areas accounted for 56.805%, 22.800%, 16.474%, and 3.921%. The results show that the geological environment quality of the study area is generally good, and some areas are poor, and very few are bad. The calculated evaluation map is compared with the current geological disaster points, and the results verify the accuracy and scientificity of the evaluation process and results. The research results of this paper can provide a basis for regional geological environment management, planning, disaster prevention and mitigation.

Research on development characteristics and failure mechanism of land subsidence and ground fissure in Xi'an, monitored by using time-series SAR interferometry

The development characteristics of land subsidence of Xi'an by an advanced InSAR technique are investigated based on Envisat, Radarsat-2 and Sentinel-1 satellites, and it can be found that there still have been five typical land subsidence bowls with maximum subsidence rates beyond 40 mm/year in Xi'an. In 2012, the land subsidence took on slightly slowing down with a ground rebound area of up to 6.3 km2. But in 2003–2010, 2016 and 2017, there was more serious land subsidence and especially in 2017 the maximum velocity reached up to −137 mm/year. Yuhuazhai-Nanyaotou subsidence bowl as the greatest subsidence bowl, its area that rate was below 50 mm/year in 2017 was up to 10.64 km2. Moreover, these land subsidence bowls mainly concentrate upon tectonic depression area due to huge thickness clay soil and are spatially and temporally coincident with confined aquifer depression cones, suggesting that over-exploitation groundwater plays a decisive role for land subsidence. Ground fissure belts are generally controlled by normal faults in Xi'an, but asymmetry settlement of land surface can also give rise to the abnormal activities of ground fissure belts, which have caused serious threat or damage to building structures. In addition, it could also be found that surface uplift area in 2012 involves in both the tectonic depression area and loess ridge in terms of their same thickness sand layer.

Dynamic Characteristics of Metro Tunnel Closely Parallel to a Ground Fissure

Shaking table model test and numerical simulation model were conducted on scaled tunnel model to investigate the mechanism and effect of seismic loadings on metro tunnel which is closely parallel to an active ground fissure. Key technical details of the experimental test were set up; for example, similarity relations, boundary conditions, sensors layout, and modelling methods were presented. Synthetic wave, El Centro wave, and Kobe wave were adopted as the input earthquake waves. Results measured from shaking table model and numerical model were compared and analyzed. It is found that the fissure increased the dynamic response features as accelerations and strains of the tunnel, especially in the part close to the fissure. Average incremental percentage of acceleration amplifying coefficient was 8.33% from the wall close to fissure than the symmetrical one. The short distance to fissure led to serious circumferential dynamic strain, while the distance to fissure influenced the axial dynamic strain less. The numerical analysis results have a good correspondence with those of the shaking table model test. The waves at the top of tunnel have more scattering and emission effect. The fissure increases the dynamic response of the tunnel close to it.

Experimental study on Su-Xi-Chang earth fissures induced by repeated groundwater pumping and impounding

Surface subsidence and fissures, especially surface fissures, are typical geological disasters related to groundwater activities in the Su-Xi-Chang area, China. In this study, we first analysed the geologic background and hydraulic features of earth formation in the area and constructed a physical model and its related experimental system in the laboratory. Based on the model and the system, we further experimentally studied and theoretically analysed the mechanism of ground fissure formation. The results showed that development of the earth fissures obviously undergoes the following stages. First, under self-gravity, the soil (artificial sand) layers in the model box with larger void ratios are gradually compacted, leading to uneven surface subsidence. Second, although the excess pore-water pressure could cause the surface to rise locally and macroscopically, water impounding on the aquifer lowers the friction among sand grains to certain degree depending on the strength of seepage in the horizontal direction, resulting in surface deformation and subsidence. Third, strong water pumping instantaneously releases excess pore-water pressure, resulting in soil consolidation in the vertical direction. Therefore, repeated groundwater impounding and pumping together with unique geological conditions lead to the formation of earth fissures in the Su-Xi-Chang area.

Factors that trigger the development of mining-induced ground fissures, and standards to treat them in shallow coal mining areas

Factors that trigger the development of mining-induced ground fissures, and standards to treat them in shallow coal mining areas