Ground Fissures Research Articles

Monitoring and mechanisms of ground deformation and ground fissures induced by cut-and-fill mining in the Jinchuan Mine 2, China

As an advanced mining technology, cut-and-fill mining was successfully applied in the Jinchuan Nickel Mine over 18 years until the end of 1999 when ground fissures occurred above the ore body. Since the first field investigation of the ground fissures in 2000 and the establishment of GPS monitoring network in 2001, ground deformation and damage has been continuously monitored and researched for the last 10 years. By the end of 2010, the maximum vertical displacement reached 1,720 mm and accompanied by the rapid development of ground fissures. This study considers the effects of large-scale stress adjustment and redistribution, hysteretic backfill, low strength of filling body, unfilled void space, as well as repeated mining activities concurrently caused ground deformation and ground fissures. Besides, the hysteretic mechanisms of ground response relative to the mining operations and the mechanisms of displacement variations are discussed from different perspectives. The results provide invaluable information on designing and building mines with the cut-and-fill method.

Research on tectonic causes of numerous ground fissures development mechanism and its unbalance distribution between eastern and western of Weihe basin

Based on the high precision GPS monitoring data from 2001 to 2008, the finite ELEMENT dynamic model of Weihe basin is established, combined with its tectonic characteristics Using above model the regional crustal stress field characteristics is studied, and the intrinsic relationship between the tectonic stress field and numerous ground fissures of Weihe basin is also analyzed thoroughly. For the first time the inherent dynamic relationship between the tectonic stress field and numerous ground fissures of Weihe basin is revealed quantitatively by the spatial geodetic, And the root causes of its unbalanced distribution between eastern and western of Weihe Basin is also revealed .. The results show that the present crustal stress fields of Weihe basin have significant difference, the eastern part mainly shows extension stress field with NW-SE direction while the western part mainly shows compression stress field with NE-SW direction, and overall showed relatively sinistral movement trend, which has good inheritance with the regional previous long-term tectonic deformation. The analysis discloses that the regional tensional stress field with NW-SN direction is the power source mechanism of numerous ground fissures development in the central and eastern of Weihe basin, while the differences of tectonic stress fields is also the fundamental reason for cracks unbalanced development in the eastern and western of Weihe Basin. Further analysis shows that the ground fissures in the Weihe Basin have strong tectonic characteristic, they are shaped by active faults with creep slipping ruptured soil under above power source mechanism. It is believed that the results in this paper could provide important information for the prevention of basin ground fissures disasters and city safety constructions.

Mechanism Analysis of Tectonic-Type Ground Fissures in Shanxi down-Faulted Basin

Shanxi downed-faulted basin mainly consists of Datong basin, Taiyuan basin, Linfen basin and Yuncheng basin, having thick quaternary stratum. Affected by geological structure, topography, stratum conditions and other factors, ground fissure disasters are well developed. Using the development and evolution of tectonic-type ground fissures in the faulted basin as research objects, from the two aspects of horst-graben structure and basal activity of fault belt, this study explored the causes of quaternary ground fissures in Shanxi down-faulted basin. Studying the distribution characteristics, formation mechanism and the disaster-causing effects has the theoretical significance of a better summary and understanding on ground fissures and other geological disasters, as well as providing theoretical basis for prediction and prevention means of the disasters.

Numerical Simulation Analysis of Buried Ground Fissures’ Propagation in Xi’an

Ground fissure disasters are main environmental geological hazards in Xi’an. Therefore, carrying out researches on causes of cracks and mechanisms of hazard-formative, as well as setting economical and effectively countermeasures are major geological disaster puzzles to be solved.According to the key issues existing in the ground fissure researches, we use numerical simulation analysis method to solve them. Numerical simulation analysis shows that, it is reasonable that we use elastic breaking theory to describe its rupture propagation process. This paper introduces smeared crack model and explains the fracture morphology and process of sample which has microcracks inside it. Results show that such sample’s tensile strength is greatly weakened and its tensile failure is brittle fracture. Differential subsidence movement on both sides of the buried ground fissure (fault) not only leads to upwards propagation of existing cracks, whose tendency are opposite to the existing ones, but also leads to the development of nearly vertical crack belt, which is located on the uplift block and develop from top to down. Because of width of buried ground fissures’ affected zone depends on many factors, there are still lots of work to be done on the division of buried ground fissure’s deformation zone.

Monitoring of Ground Fissures Induced by Underground Mining

Aim to analyze the development trend of ground fissures, new type of deformation monitoring device was developed. The device was used to measure the deformation of ground fissures in metal mine. The results showed it was feasible to monitoring the three-dimensional deformation. This study could provide reference for the similar condition mine.

Geoseismological investigation of the January 26, 2001 Bhuj earthquake in western peninsular India

Of the intraplate seismic events, the January 26, 2001 Bhuj earthquake (Mw 7.7) would be remembered as one of the deadliest, in which 13,805 human lives were lost, 0.177 million injured and a total of 1,205,198 houses were fully or partly damaged in 16 districts of Gujarat state with an estimated overall loss of Rs. 284, 23 million. The brunt of the calamity was borne by five districts, namely Kachchh, Ahmadabad, Rajkot, Jamnagar and Surendranagar, where 99 % of the total casualties and damage occurred. In the neighbouring parts of Sindhh Province of Pakistan, 40 human casualties were reported, and some buildings cracked in the Karachi city as well. In the Kachchh district of Gujarat state, the telecommunication links and power supply were totally disrupted, road and rail links partially impaired and water supply snapped at many places. The Bhuj airbase had to be closed for some time due to damage to the infrastructure. The macroseismic survey carried out by the Geological Survey of India in an area as large as 1.2 million sq km indicated an epicentral intensity as high as X on the MSK scale in an area of 780 sq km in the central part of Kachchh rift basin. Apart from damages to civil structures, the January 26 earthquake induced conspicuous terrain deformation in the form of liquefaction features, structural ground deformation and low-order slope failures that were mainly prevalent within the higher intensity isoseists. Liquefaction occurred in an area of about 50,000 sq km. The extensive plains of Rann of Kachchh, the marshy tracts of the Little Rann and the shallow groundwater table zones of Banni Land provided the most conducive geotechnical environments for the development of seismites. The liquefaction activity was profuse in seismic intensity zones X and IX, widespread in intensity VIII, subdued in intensity VII and stray in intensity VI. The common forms of liquefaction were sand blows/boils, ground fissures, craters, lateral spreading and slumping. Ground deformation of tectonic origin was witnessed in the epicentral tract. Such features, though much less subdued in comparison with the 1819 large earthquake (Mw 7.8) in region, occurred along the Kachchh Mainland fault (KMF) and along a transverse lineament, referred to as Manfara–Kharoi fault. The manifestations were in the form of fractures, displacement of strata, linear subsidence, upheaval, formation of micro-basins/micro-ridges, ripping off of rock surface, and at places violent forms of liquefaction. The localities where coseismic deformations were observed include Bodhormora, Sikra, Vondh, Chobari, Manfara and Kharoi. The 2001 event has demonstrated the role of local geology in influencing the ground motion characteristics and, therefore, the hazard estimation.

Case Study of Ground Fissures Generated by Liquefaction Following the Wenchan Earthquake

Ground failure caused by liquefaction is a major cause of earthquake damage and casualties during many history earthquakes. The gravels liquefaction extensively occurred following the 2008 Wenchuan Ms8.0 Earthquake, and 70-80% liquefied sites generated lots of 100 meter to hundreds kilometer long and 5 centimeter to 50 centimeter wide ground fissures, which intersected house, farmland, etc. and caused serous damage. The mechanism of the building damage and ground fissures were investigated by borehole drilling and Multi-Channels Electricity Resistance Test. The detailed in-situ tests and comparison show that: (1) The building, whose foundation intersected by liquefaction, suffered more severe damages than its surrounding buildings; (2) The abundant ground fissures were generated by gravels liquefaction rather than the raptures or secondary faults; (3)The fundamental conditions for the generation of ground fissures by liquefaction are: flat ground surface (slop less than 3%), horizontal non uniform distribution of liquefiable soils.

Liquefaction Macro-Characteristics in Chengdu Region in Wenchuan Ms8.0 Earthquake

In Wenchuan earthquake, liquefaction phenomena and relevant damage in Chengdu region was extensive. Through field investigation, macro-liquefaction characteristics in Chengdu region are outlined, i.e., (1) Liquefaction zones (belts) mainly were located in Dujiangyan city; (2) Liquefaction has been observed in seismic intensities VI, VII, VIII, IX and X, but mainly concentrated in intensities VII and VIII; (3) Heights of liquefaction water-jet mostly ranged in 1m to 3m, and the highest was more than 10m; (4) The ejected materials in liquefied sites covered many soil categories, nearly 67% of fine sand and 11% of gravel; (5) Liquefaction generally caused ground fissures, but obvious ground subsidence were not detected. Although the ejected materials mainly were fine-grained soil, the actual liquefaction was prevalent gravel soil

Liquefaction Macro-Characteristics in Chengdu Region in Wenchuan Ms8.0 Earthquake

In Wenchuan earthquake, liquefaction phenomena and relevant damage in Chengdu region was extensive. Through field investigation, macro-liquefaction characteristics in Chengdu region are outlined, i.e., (1) Liquefaction zones (belts) mainly were located in Dujiangyan city; (2) Liquefaction has been observed in seismic intensities VI, VII, VIII, IX and X, but mainly concentrated in intensities VII and VIII; (3) Heights of liquefaction water-jet mostly ranged in 1m to 3m, and the highest was more than 10m; (4) The ejected materials in liquefied sites covered many soil categories, nearly 67% of fine sand and 11% of gravel; (5) Liquefaction generally caused ground fissures, but obvious ground subsidence were not detected. Although the ejected materials mainly were fine-grained soil, the actual liquefaction was prevalent gravel soil

Case Study of Ground Fissures Generated by Liquefaction Following the Wenchan Earthquake

Case Study of Ground Fissures Generated by Liquefaction Following the Wenchan Earthquake

Performances Analysis of Tall Concrete Frames on the Ground Fissure Field

Through predict activities trend of ground fissures, given to the ground surface subsidence curve on the topper side in the next 50 years. Established a tall concrete frame construction model, using SAP2000 finite element programs, take a distance of the building depart from the fissure as analytical variables, in considering the dead load, live load, horizontal seismic action and combine with foundation differential settlement working conditions, analyze the elastic displacement and internal forces of the structure. The results showed that，in the topper side area near to the fissure, affected by the avoidance distance, the displacements and internal forces of the frame structure change remarkably. The growth and redistribution of internal forces performance are the most serious in the building base floor of framework， the internal forces change in ends of both beam and column will cause a change in the direction of bending moment， but also an inflection point of the column will change with the internal forces growth and regression.

Finite element numerical simulation of land subsidence and groundwater exploitation based on visco-elastic-plastic biot's consolidation theory

The land subsidence due to groundwater exploitation has an obvious hysteretic nature with respect to the decrease of the under groundwater level, and the uneven settlement often causes ground fissures. To study these important features, a visco-elastic-plastic constitutive relationship with consideration of the coupling of seepage and soil deformation is proposed, and a finite element model with variable coefficients based on the Biot's consolidation theory is built. With the groundwater exploitation and the land subsidence control in Cangzhou City, Hebei Province as an example, the variations of the under groundwater level and the development of the land subsidence due to the groundwater exploitation are simulated and ground fissures are predicted by the horizontal displacement calculation. The results show that the lag time between the land subsidence and the under groundwater level descent is about a month, and the simulated results of fissures agree well with the observed data. The model can well reveal the characterization of the interaction between the land subsidence and the groundwater exploitation.

Analysis of Present Tectonic Stress and Regional Ground Fissure Formation Mechanism of the Weihe Basin

In this paper, the crustal horizontal velocity fields of the Weihe Basin and the Xi'an area are determined using high-precision GPS campaign measurements, which in turn provide constraints to calculate tectonic stress fields. A finite element dynamic model is employed for the Weihe Basin and an elastic block model for the Xi'an area. It is suggested that the ground fissures in the Weihe Basin are shaped by active faults under the effect of a NW-SE regional tension stress field. Fault motion is the fundamental factor influencing the ground fissures and controls their directions and distribution, though the excessive extraction of underground water might be another major factor that accelerates the development of ground fissures. It is believed the results obtained in this study can provide important information for the prevention of basin ground fissure disasters and aid urban construction.

A Study on the Formation Mechanism and Preventive Measures of Coal-Mining Ground Fissures in the South-West of Pingyao

According to the basic characteristics of geological environment in Pingyao mining area, we analyzed the relationship between coal mining and the ground fissure disasters in recent years. The result shows that the mine goaf is the essential factor for the formation of ground fissure, and the precipitation and groundwater drainage accelerates its development. Based on a systematic analysis of classification of goaf as well as the distribution characteristics and the formation mechanism of ground fissure, we found that the ground fissure in this area is non-tectonic, and thus proposed corresponding prevention and control measures. Research results would provide basis for the improvement of local environmental conditions and the control of geological disasters.

Safety Analysis of Tunnel in Gob of High Steep Thick Coal Seam (I) - 2-D Numerical Simulation for Response

Taking Wusongshan Tunnel in Tongling City as an example, two-dimensional numerical simulation of new large span highway tunnel directly through gob of steep coal seam were carried out to study the response of surrounding rock induced by mining. The actual location and scale of the ground fissure consistent well with the simulation results, which verified the analysis. The results showed that, different from those in gob of horizontal or gently inclined coal seam, the response of surrounding rock in gob of steep coal seam have the following characteristics: (1) shallow mining affects significantly on the values of settlement of earth surface and the tunnel, and deep mining on the scope; (2) in the shallow layer, a small scale coal being reserved or being effective filled after excavation can benefit greatly to the safety of structure and stability of the surrounding rock; (3) sharper uneven settlement would occour at the floor than the roof of coal seam, which can threaten the tunnel structure and should attract more special attention; (4) for this project, deep faults affect the safety of structure of tunnel and stability of surrounding rock also. Based on these results, treament plan were developed of Wusongshan Tunnel, which can also be refered for other similar projects.

Identification of Loriya Fault, Its Reactivation Due to 2001 Bhuj Earthquake, (Using Remote Sensing Data) and Its Bearing on the Kachchh Mainland Fault, Kachchh District, Gujarat

The 2001 Bhuj earthquake (Mw 7.7), one of the most severe earthquakes in the recent history of India, reactivated various existing active faults. It is manifested in the form of coseismic ground fissures/cracks and upheaval of land in the form of bumps. Identification and reactivation of Loriya Fault is established by 1—Geomorphic changes with the help of digital imagery (LISS III images). 2—Coseismic changes through ground checks and 3—Geophysical signatures through magnetic and gravity survey. A lineament cutting the north-western part of the Pur River alluvial fan has been revealed by satellite imagery. The streams flowing along the lineament add to the evidences of a weak plane, while the occurrence of coseismic ground fissures confirms the existence of an active fault. No dip slip movement is recorded in the trenches made across the Loriya active fault while the en-echelon pattern of ground fissures suggest strike slip movement along the fault due to 2001 earthquake.

Experimental study of two saturated natural soils and their saturated remoulded soils under three consolidated undrained stress paths

In this paper, an experimental investigation is conducted to study the mechanical behavior of saturated natural loess, saturated natural filling in ground fissure and their corresponding saturated remoulded soils under three consolidated undrained triaxial stress tests, namely, conventional triaxial compression test (CTC), triaxial compression test (TC) and reduced triaxial compression test (RTC). The test results show that stress-strain relation, i.e. strain-softening or strain-hardening, is remarkably influenced by the structure, void ratio, stress path and confining pressure. Natural structure, high void ratio, TC stress path, RTC stress path and low confining pressures are favorable factors leading to strain-softening. Excess pore pressure during shearing is significantly affected by stress path. The tested soils are different from loose sand on character of strain-softening and are different from common clay on excess pore water pressure behavior. The critical states in p′-q space in CTC, TC and RTC tests almost lie on one line, which indicates that the critical state is independent of the above stress paths. As for remoulded loess or remoulded filling, the critical state line (CSL) and isotropic consolidation line (ICL) in e-log p′ space are almost straight, while for natural loess or natural filling, in e-log p′ space there is a turning point on the CSL, which is similar to the ICL.

Morphometry of eyes, antennae and wings in three species of Siagona (Coleoptera, Carabidae)

In carabid beetles, physiological and behavioural characteristics reflect specific habitat demands and there is a strong correlation between body form and habit in species with different life style. In this study, we compared the morphometry and compound eye characteristics of three species of the genus Siagona: Siagona jenissoni, Siagona dejeani and Siagona europaea. These carabids have a stenotopic lifestyle in Mediterranean clayey soils, inhabiting the ground fissure system formed during the dry season. All species have a Mediterranean distribution and are nocturnal olfactory hunters, and are strict ant predators. For morphometric measurements, we considered body length (mm), wing length (mm), antenna length (mm), head width (mm), trochanter length (mm), number of ommatidia, eye surface area (mm2), ommatidia density (number of ommatidia/mm2 of eye surface area), head height (mm), thorax height (mm) and abdomen height (mm). The data revealed intersexual and interspecific differences. The three species differ in relative length of the antennae, density and number of ommatidia and relative trochanter length. Significant differences occurred in wing sizes, which are well developed in Siagona europaea, the only species capable of flight. When eye size is compared with other ground beetles of various lifestyles, Siagona shows pronounced “microphthalmy” an adaptation to subterranean life in clayey crevices of tropical and subtropical climates with a marked dry season.

Study on Interaction between Soil and U-Shaped Subway Tunnel in the Environment of Ground Fissures

The interaction mechanism, between soil and U-shaped Subway tunnel, is studied by numerical simulation in the environment of ground fissures. The Subway Line 2 through the ground fissures in Xi’an. The analysis results show that the soil mass influenced by the relative displacement and the vertical displacement gradually increases with the relative displacement increasing of ground fissures movement. The deformation area of tunnel lies in the two sides of presupposed ground fissure, and the area enlarge with vertical relative displacement increasing. The tunnel structure damages at the ground fissures when the relative displacement reaches to 100mm. The footwall part is in tension and the hanging wall part is under pressure on the top of tunnel structure at the ground fissure. The footwall part is under pressure and the hanging wall part is in tension on the bottom of tunnel structure at the ground fissure. In the practical projects, the sectional type tunnel should be employed when the Subway tunnel through the ground fissures.

The Active Mechanism of Xi’ an Ground Fissures and Discussion on a New Material for the Ground Fissure Disaster Prevention

The genesis of Xi’ an ground fissures and the recent activity characteristics and tendency have been introduced firstly. The architectural damage caused by ground fissures and current hazard prevention methods have been described secondly. The applications of a new material used in controlling underground engineering and coal mine disaster have been introduced. The mechanical properties of the new material have been stated also. As a result, a new foundation treatment method has been envisaged to make it possible to construct architectures on ground fissures.