Ground Rock Research Articles

The Influence of Geotechnical, Geological and Mining Factors on the Formation of Sinkholes at Lubambe Mine, Zambia

Mining-induced sinkholes are a common feature in underground mines. Sinkholes usually disrupt mining operations and associated infrastructure when they occur. This paper presents a case study of the Lubambe copper mine, where nine (9) sinkholes have been reported on the eastern and southern limbs. The development of sinkholes has resulted in increased mining costs due to the closure of the 182 mL decline on the eastern limb and the 175 mL truck route on the southern limb. This study establishes the influence that poor ground formation, rock stability, geological structures, and inappropriate mining practices have on the formation of surface sinkholes. Assessment of ground condition was done by core logging, and borehole analysis was conducted using GEM4D-BasRock software to classify the rock mass quality based on RQD, RMR, Q-System and GIS. Assessment of the mining operational environment was focused on the effects of varying stope designs and sequencing on ground stability. Results of the study indicate that the formation of surface-induced sinkholes is attributed to historical mining in weak rock formation and weathered rock coupled with subsequent failure of unsupported stopes with stope height between 8 and 25 metres and less stand-up time of 7 days.

Lithology and subsurface structures related to gold mineralisation in the Kibati prospect, Mozambique belt in eastern Tanzania, with implications for gold exploration

This paper provides an insight into the structures, lithologies, and potential zones and their relationships to gold mineralisation that were investigated to decipher the controls of gold mineralisation at the Kibati Gold Prospect within the Mozambique Belt. Although the Kibati area is located within the gold mineralised zone, lithology and subsurface geological structures associated with gold mineralisation are not well studied. The available high-resolution aeromagnetic data have not yet also been analysed and interpreted to derive geological features that are useful in mineral exploration. The investigation of the structures and lithologies was accomplished through integrated interpretation of high-resolution aeromagnetic data, ground magnetic data, geological mapping, and rock sampling. Aeromagnetic and ground magnetic results reveal the presence of two structural systems, which were previously not identified that trend in NW–SE and NE–SW, with the NW–SE being the dominant control of gold mineralisation. The subsurface structure with NW–SE trending controls the mineralised fluids as a consequence of gold mineralisation in the surface lithologies. Petrography and geological mapping show that granitic gneiss, garnet-biotite quartzo-feldspathic gneiss, dolerite, and amphibolite are the main exposed outcrops where the first two identified types of gneisses, based on their protolith, were previously not specified. Based on the gold assay results, which are persistent and collinear to the structural trend of NW–SE picked out by magnetic data, two (2) potential blocks (A and B) were identified. The trend of the structure in blocks A and B when overlaid with gold anomalies indicates that most of the gold concentrations are located in block B and the highest value of gold concentrations is located in block A where gold values range from 10.19 to 19.680 g/t in block A and 0.0623 to 4.419 g/t in block B. The difference in gold values between blocks A and B is due to the variation in the degree of alteration. The integration of the results indicates that the gold mineralisation in the Kibati area is structurally controlled and concentrated in shear zones. The findings therefore, indicate that the Mozambique Belt is potential for gold mineralisation and provide a warrant for future plan for gold exploration.

Influences of ski-runs, meadow management and climate on the occupancy of reptiles and amphibians in a high-altitude environment of Italy.

Alpine ecosystems harbour a rich and highly specialised biodiversity, which is particularly susceptible to anthropogenic disturbances such as habitat loss and fragmentation as well as to climate change. Combined with other forms of land-use conversion, construction and maintenance of ski resorts can have severe consequences on alpine biodiversity. In this study, we show how one amphibian and two reptile species, namely Rana temporaria, Zootoca vivipara and Vipera berus, respond to such impacts by means of a multi-season occupancy analysis. We found all three species both in and outside ski-runs, showing that these habitats do not necessarily preclude their occurrence. Contrarily, this is influenced more by microhabitat availability, such as ground vegetation, humid areas and rock cover, rather than by macro-characteristics like elevation or habitat type. Moreover, we found a climatic influence on the year-to-year occupancy change of the species, with activity-month conditions being more relevant than overwintering ones. Our results demonstrate how, in the specific case of reptiles and amphibians, ski resorts do not necessarily limit species' occurrence and that a mild series of management actions might secure the species' persistence in the area.

Rockburst risk control and mitigation in deep mining

It is important to understand and manage rockburst challenges in deep mining operations. This paper presents a systematic study of rockburst risk in underground mining, offering a detailed examination of influencing factors, risk assessment, and various control and mitigation methods. The complexities of rockburst phenomena are explained by examining factors that lead to the occurrence of rockbursts. A rockburst risk assessment using a bow-tie analysis is conducted, which provides insights into both risk evaluation and proactive control and mitigation systems.The core of the paper presents a comprehensive array of rockburst risk control and mitigation methods, which range from controls to reduce rockburst hazard, and excavation vulnerability, to controls and mitigations to reduce exposure. Strategic engineering control methods, including mine design and mining sequencing, are discussed. Tactical engineering control measures, such as ground pre-conditioning and rock support, are scrutinized, along with administrative controls like evacuation and re-entry protocols and the use of mechanized equipment. A multiple-line defense system is advocated for rockburst risk management to address the uncertainties involved in the process.Finally, emerging technologies and innovations as well as challenges are discussed, providing a roadmap for continued advancements in rockburst risk management in the future. This work serves as a valuable resource for mining professionals, researchers, and policymakers seeking a comprehensive understanding of rockburst risk management in deep mining.

Curve fitting for seismic waves of earthquake with Hermite polynomials

We investigate and study on mathematical structures involving mathematical models and others associated with seismic waves in an earthquake. Our first aim is to give some novel formulas and certain finite sums including the Bernoulli numbers and the Hermite polynomials with the aid of generating functions, the Riemann integral, and the Volkenborn integral. The second aim is to examine the seismic wave propagation in different geological units with the help of special polynomials containing the Hermite polynomials and their graph fitting of functions. To evaluate the shape of the seismic waves propagating within the ground (rock and/or soil), we use comparing method with the graph of the Hermite polynomials and functions and the polynomial Rocking Bearings. Furthermore, we also define generating function for the polynomial type Rocking Bearings. We give open problems on this generating function and earthquake facts. By applying partial derivative operator to the generating function for the m-parametric Hermite type polynomials, we give a novel recurrence relation and derivative formulas for these polynomials. We also give a new general formula for monomials in terms of these polynomials. Moreover, for the purpose of visualizing curve fitting approach to the seismic waves, we draw many plots of the Hermite functions with Mathematica (Version 12.0.0) with their codes. Finally, with the aid of these graphs, we give useful evaluation on the shapes of the seismic waves propagated in the ground (rock and/or soil).

ДОСЛІДЖЕННЯ ДЕФОРМАЦІЙНИХ ВЛАСТИВОСТЕЙ ОХОРОННИХ СПОРУД ІЗ ПОДРІБНЕНОЇ ПОРОДИ В УМОВАХ СТАТИЧНОГО НАВАНТАЖЕННЯ

Purpose. Investigate the deformation properties of structures made of ground rock under static load conditions to preserve the integrity of the side rocks in the produced space of the coal massif and the operational state of the preparatory mine workings along the length of the excavation site. Methodology. In laboratory conditions, experimental samples of protective structures made of ground rock of heterogeneous granulometric composition were subjected to static loading under conditions of uniaxial and compression compression. Results. It was experimentally established that under the conditions of uniaxial compression of protective structures made of ground rock with the possibility of its lateral expansion, the effect of forming the bearing capacity is manifested in the relative change of the volume of the embedded material in the range of values , when, after increasing the relative deformation, the resistance reaches the maximum compaction of the rock . In such conditions, it is necessary to ensure the stability of the bearing pillar of the embedded material. During compressive compression of crushed rock, such an effect is achieved in conditions where the relative change in the volume of the embedded material is . After maximum compaction , the resistance of protective structures increases. Scientific novelty. The type of functional dependence between the relative deformation is established protective structures made of crushed rock and relative volume of the embedded material under static load under uniaxial and compressive compression, which allows to evaluate the bearing capacity of flexible supports. Practical significance. In order to assess the stability of protective structures made of crushed rock, which are in different compression conditions during the unloading of coal massif, it is necessary to take into account the compaction coefficient of the original material and the longitudinal deformation of the support under load. Keywords: coal massif, guard building, ground rock, uniaxial compression, compressive compression.

Distribution of the Surface Ruptures in the Kalaotoa Due to the 2021 M w 7.3 Flores Sea Earthquake, Indonesia

A magnitude 7.3 earthquake occurred at precisely 11:20 on December 14, 2021, within the Flores Sea region of Indonesia, precipitating a consequential landslide event. This seismic incident induced the creation of an extensive rupture zone spanning approximately 8 kilometers along the Kalaotoa fault (KF) system, which exhibits an NNE-NW-SSE trend. The objective of this study was to concentrate specifically on the Kalaotoa Island vicinity, situated approximately 40 kilometers from the earthquake’s epicenter, encompassing meticulous orientation and comprehensive field surveys conducted during the reconnaissance phase. The results of the ground assessment have been combined with spatial analysis data to ascertain the configuration and dispersion of ruptures subsequent to the earthquake, thus delineating the affected region as a prospective area susceptible to seismic events and subsequent calamities. In the vicinity proximate to the northern epicenter, fractures resulting from the seismic activity were consolidated, exhibiting considerable devastation in the form of ground fissures, rock avalanches, landslides, and structural collapses, and were predominantly oriented in a roughly NE-SW direction. Notably significant are the southern beaches of Lato’do and the eastern extremity of the rupture zone in the Lembang Mate’ne area, where coastal transgression and extensive inundation during high tides have been observed due to subsidence of 1.2 meters since the 2021 Flores Sea earthquake. Horizontal displacement around Kalaotoa Port, north of the Karumpa-Kawawo area. Displacement distribution, slip sense, and crustal deformation after earthquake propagate unilaterally to the north, resulting in a movement of the northeast side of the fault concerning SE.

Estimate of Responses of Multistoried Building under Earthquake Ground Motion to Prevent Failure

Seismic microzonation is defined as the process of subdividing a potential seismic or earthquake-prone area into zones with respect to some geological and geophysical characteristics of the sites such as ground shaking, liquefaction susceptibility, landslide, and rock fall hazard, earthquake-related flooding, etc. Very often, the seismic data are used from existing ground motion data that are related to other geographical regions and thus leads to unrealistic predictions. In this analysis, normalization of the available earthquake data is carried out for a better realistic prediction of building response. An extensive study is carried out in this work that involves two major types of buildings, microzones, and soil conditions. Fixed base, hard, medium, and soft soil have been considered for this analysis. The effect of actual and normalized ground motion for specific microzones having plan asymmetric and symmetric structures is not yet studied in prior research. The analysis has been done by finite element-based software. The present study makes an effort to determine the fundamental responses of plan asymmetric building in different kinds of soil in certain microzones. Maximum shear forces and bending moment have been seen in hard soil base conditions among all other supports. Responses of microzone II and actual ground motion are almost the same in dynamic analysis.

Developmental Features, Influencing Factors, and Formation Mechanism of Underground Mining-Induced Ground Fissure Disasters in China: A Review.

Mining-induced ground fissures are one of the major geological disasters affecting coal mines. In recent years, many effective monitoring methods have been developed to explore the developmental characteristics and nature of mining-induced ground fissures for being treated scientifically. This paper is mainly on the development law and mechanism of mining ground fissure research results which have been comprehensively combed, highlighting the development trend, including the formation condition, development features, influencing factors, and mechanical mechanism of mining-induced ground fissures. Outstanding issues are discussed and future research hot spots and trends are pointed out. The major conclusions include: (1) under the shallow coal mining condition, because the rock layer fault zone directly reaches the surface, the ground fissure usually develops seriously; (2) mining-induced ground fissures are generally divided into four types: tensile fissures, compression fissures, collapsed fissures, and sliding fissures; (3) mining-induced ground fissures are affected by the coupling effect of underground mining and surface topography. The main factors are geological mining conditions, surface deformation, and surface topography, including rock and soil structure, rock and soil mechanical properties, surface horizontal deformation, surface slope, and so on; and (4) to ensure the safety of underground mining, temporary ground fissures formed during the process of coal mining must be treated when ground fissures and rock ground fissures are connected. The results of this article make up for the deficiencies of the relevant research, provide the basis and direction for future research, and have universal applicability and scientific guiding significance.

A preliminary analysis of the mining-induced rock movement characteristics in the Xinli deposit of the Sanshandao gold mine

Commensurate with economic globalization, the demand for mineral resources is increasing. With increased mining activity, problems related to ground subsidence and rock movement are becoming increasingly prominent, even affecting mining production activities. However, the physical mechanisms behind the ground subsidence phenomenon have been poorly studied, especially for metal mines with a steep dip. This paper applies the Interferometric Synthetic Aperture Radar (InSAR) technique and the numerical simulation method to deduce the characteristics of rock movement in the Xinli deposit of the steeply inclined Sanshandao gold mine. The InSAR results indicate that more subsidence has occurred in the southern part of the Xinli Village coastline area than in the northern part. This is also supported by the numerical simulation results obtained by the fast Lagrangian analysis of continua in three dimensions (FLAC3D). Notably, the range of ground subsidence obtained by numerical simulation shows an obvious asymmetry. The monitoring data of the No. 55 prospecting profile offer a plausible explanation for this, as the surrounding rock of the fault’s hanging wall has a wider range of rock movements. Furthermore, the sublevels of the No. 55 prospecting profile at different depths show different rock movement characteristics, and a logistic function can be well applied to the right part of the settlement curve; the parameter “a” in the function formula is very close to the maximum subsidence value for each sublevel. We defined the ratio “r” to measure the difference between the maximum subsidence value and the corresponding parameter “a” and found this value to be positively correlated with the fractal dimension value of deeper sublevels (−320 m, −400 m, −480 m, and −600 m) and negatively correlated with the fractal dimension value of lower sublevels (−200 m and −240 m).

Mosquito (Diptera: Culicidae) Diversity and Community Structure in Doi Inthanon National Park, Northern Thailand.

Simple SummaryMosquitoes are small flies, some of which are known as principal vectors of the pathogens that cause dengue, malaria, filariasis, chikungunya, Japanese encephalitis, and Zika in many countries of the world. However, the majority of the species are important components of ecosystems. We evaluated the diversity and community structure of mosquitoes in Doi Inthanon National Park, named for the highest mountain in Thailand. The park mainly consists of natural forest, but it hosts a number of human activities. A total of 140 mosquito species were identified among 3,795 specimens. The most dominant genera were Culex (34.3%), Aedes (19.3%), Anopheles (13.6%), Uranotaenia (10.7%), and Armigeres (5.8%). The five most abundant species were Ae. albopictus, Ae. vittatus, Cx. bitaeniorhynchus, Cx. mimulus, and Tripteroides aranoides. Species richness was higher in the rainy season than in the cold and hot seasons. Natural phytotelm habitats for immature stages had a higher diversity than artificial container habitats. A greater number of species were found in forest areas than in agricultural areas and villages. Ground pools, stream pools, rock pools, bamboo stumps, bamboo internodes, and rice fields were the most preferred natural habitats. Ground pools, rock pools, and stream margins, which had a high diversity index, were the most important habitats for mosquitoes in the park.Urbanization and human activities create new suitable aquatic habitats for the immature stages of mosquitoes in many countries. This also applies to Doi Inthanon National Park in northern Thailand, which is named for the highest mountain in the country. Despite its popularity, there is no information regarding mosquito diversity and community structure in the different ecosystems of the park. Monthly collections of immature stages from various habitats were conducted from August 2004 to December 2005 using dipping and sucking methods. The specimens collected from each habitat were reared to adults and identified based on their morphology. Diversity parameters and community structure were statistically analyzed. A total of 140 species (3795 specimens) belonging to 15 genera were identified. Among these, four genera (Culex, Aedes, Anopheles, and Uranotaenia) had high species richness, each represented by 48, 27, 19, and 15 species, respectively. Aedes albopictus was the most relatively abundant species, representing 6.7% of the total number of captured specimens, followed by Tripteroides aranoides (5.6%) and Cx. mimulus (5%). Species richness in natural habitats was significantly higher than in artificial containers. Species richness and abundance were highest in the rainy season. In comparison to agricultural areas and villages, mosquito diversity was found to be higher in forest areas. Ground pools, stream pools, rock pools, bamboo stumps, bamboo internode, and rice fields were the most preferred natural habitats. The results indicate that Doi Inthanon National Park has a high mosquito diversity. Each species exhibits differences in abundance and distribution in different habitats, which is useful information for planning conservation measures and vector control in the park.

Geologic, Geomorphologic, and Climatic Preparatory Conditions for the Evolution of the Dangkhar Landslide, Himachal Pradesh, India

Abstract With an estimated volume of approximately 15 to 20 km3, the Dangkhar landslide located in the Spiti valley, Himachal Pradesh, India, is one of the largest landslides on earth. Its initiation is geochronologically constrained to have occurred during the late Pleistocene and may be related to glacial retreat following local last glacial maximum, which, depending on the source, occurred around 80 to 30 ka years ago. There is significant value in understanding the causative factors contributing to such an enormous and rare event. On the basis of comprehensive field studies and laboratory investigations, it is concluded that erosional, structural, and depositional features within and surroundings of the Dangkhar landslide are critical for understanding landslide initiation and its long-term behavior. The landslide developed as a block slide along a synformal flexure, and through-cutting lateral valleys fulfill the kinematic conditions for creating a massive removable block of earth. Deposits of weakly cemented and crudely bedded carbonate breccias in the landslide’s toe region represent depositional activity during recession of the main valley glacier, and cross-cutting structural relationships involving ground ruptures (lineaments) and rock glaciers in the head region record long-term, ongoing landslide deformations subsequent to its initiation. Stable isotope signatures of samples indicate presence of freshwater associated with the formation of breccia deposits. While many details concerning the timing and development of the Dangkhar landslide remain unknown, recent studies illuminate some very important aspects. The glacial history of the Spiti valley combined with structural kinematics are clearly important factors concerning landslide development. Also important are constraints concerning the minimum age of landslide initiation after recession of a valley glacier, and structural evidence documenting long-term ongoing slope deformations.

Strength, acoustic, and fractal behavior of fiber reinforced cemented tailings backfill subjected to triaxial compression loads

Overall, solid materials like CTB (i.e., cemented tailings backfill) give out low-level seismic signals as they are under stress in underground mining applications involving ground control, rock burst, and coal bump monitoring. To offer a means of establishing zones of instability, the acoustic emission (AE) technique uses these seismic signals to study the fracture/failure behavior of CTB materials. This paper develops a highly efficient AE technique to explore the influence of type, length and dosage of fiber over strength, acoustic and fractal characteristics of CTB materials. The uniaxial compression test of fiber reinforced CTB (FRCTB) was carried out with the help of an electronic universal testing press while the triaxial compression failure process of FRCTB was recorded via the AE monitoring system. The research findings prove that polypropylene provides the best fiber reinforcement influence, offering an optimal fiber dosage and length of 0.6% and 12 mm, respectively. FRCTB’s peak strength in triaxial compression surges when confining pressure is boosted. However, non-reinforced CTB offers better confining pressure effect better than FRCTB. Besides, the ring count-time and energy-time during the triaxial compression of CTB are mainly manifested in four stages: compacting, calm, and intensive and active stages, and the fractal theory is applied to FRCTB’s fracture properties. In conclusion, this work presents a practical advice regarding the field durability monitoring/reinforcement of CTB used for ground support and a secured work platform providing access for mining workers/equipment.

Unification of the Mechanical Model and Parameter Analysis of the Elastic Foundation Beam of Pipe-Roof

Based on the existing model of pipe-roof considering the arching effect, combined with the mechanical model of pipe-roof when the tunnel is excavated to the end, a unified mechanical model of the elastic foundation beam for pipe-roof is established. Deflection and internal force calculation formulas of the model were derived. Combined with actual engineering cases, the model was compared and analyzed, and the parameters affecting the pipe-roof were analyzed by taking the unified model as an example. The results show that the established unified elastic foundation beam model can better represent the actual stress state of a pipe-roof and the model has strong applicability. The stress state of the pipe-roof at the end of excavation can be calculated by changing the boundary conditions of the model. When the diameter of the steel pipe is 108–114 mm, the supporting effect of the pipe-roof is similar. When Ec (elastic modulus of converging) > 40.0Eg (elastic modulus of ground rock), the excavation footage and the diameter of the steel pipe have little effect on the deflection and bending moment of the pipe-roof. Therefore, increasing the elastic modulus of the reinforced area is the most effective method to reduce the deflection and internal force of the pipe-roof. The longer the residual length of the pipe-roof in surrounding rock, the safer the tunnel will be during excavation. The economically reasonable value of the residual length of the pipe-roof in surrounding rock is 2–3 m.

An operational approach to ground control in deep mines

As mines go deeper and get larger, mine designs become more fragile largely due to the response of the rock mass to mining. Ground control and rock support become important levers in the mine construction schedule, production performance, and excavation health. For example, in cave mines, the production footprint together with associated mine infrastructure are significant investments in a modern caving operation. This investment must be protected and maintained to reduce the risk of ground-related production disruptions. It is necessary to preserve the health of these excavations and their maintenance through an effective rock support design. Rock support thus becomes a strategic element in asset management. This article focuses on support design for brittle ground when displacements induced by stress-fracturing consume much of the support's capacity. It deals with the functionality of the support in deforming ground. Several interlinked concepts are important when assessing excavation health. Designs must not only account for load equilibrium but also for deformation compatibility and capacity consumption. Most importantly, the support's displacement capacity is being consumed when the rock mass is deformed after support installation. Hence, it is necessary to design for the support capacity remaining at the time when the support is needed. If support capacity can be consumed, it can also be restored by means of preventive support maintenance (PSM). This concept for cost-effective ground control is introduced and illustrated on operational evidence. Furthermore, how design can impact construction costs and schedule are discussed. Support is installed to provide a safe environment and preserve an operationally functional excavation. It also must assure senior management that investments in high quality support and its maintenance will substantially reduce delays and with it, costs. It is demonstrated that the use of ‘gabion-like’ support systems can achieve these goals. A technical summary of the ‘gabion panel’ support system design is presented.

Heat capacity of dispersed rocks

Protection of automobile roads from negative cryogenic processes is a current issue to which significant attention is devoted in both scientific and engineering communities. In many cases important for practice, the the thermal factor determines the reliability and security of the use of the road in the cryolithic zone. The heat capacity of dispersed rocks is among the most important indicators of the physical properties determining the intensity of thermal processes in the road surfaces and road foundations. The precision of determination of the total heat capacity of the rocks in thawed and frozen state largely determines the precision of the forecast of the thermal regime of roads in the cryolithic zone. A complex assessment of the impact of ice content of the dispersed rocks on the value of total heat capacity was done. 2D and 3D charts which allow to assess the possible range of change in the heat capacity of the dispersed rocks in thawed and frozen state, in both a wide range and in the typical range of values, were produced. Among the main criteria determining the extent of the seasonal freezing and thawing of the soils of the active layer is the Stefan number, a dimensionless criterion. An overall assessment of the impact of ice content on the ground (rock) foundations of the roads and of the air temperature in the warm period of the year on the quantitative values of the Stefan number was done. Charts allowing to determine in both a wide and typical range the changes of values of the Stefan numbers, permitting to assess the possible range of changes of the Stefan number, were made. It was determined, in particular, that for the typical dispersed rocks of the road foundations in the cryolithic zone the range of change in the Stefan numbers is 2.1-6.5.

GIS-Based Landslide Disaster Risk Areas and Ground Movements Mapping to Support Disaster Mitigation Activities (Case Study: Tasikmalaya Regency)

Tasikmalaya Regency is an area that is prone to landslides and ground movements. The availability of comprehensive and accurate information in controlling land use for regional development in areas prone to landslides and ground movements is very important for casualty prevention and other losses such as physical, social and economic. This information must be disseminated to the public as an early warning system to support disaster mitigation efforts. Identification of the characteristics of landslide and ground movement prone areas requires the mapping of risk areas to mitigate disasters. This can be done using Geographic Information System (GIS). This mapping activity was carried out using the method of collecting digital data from five vulnerability controlling factors of landslides and ground movements, namely rainfall, rock type, soil type, land cover and slope. The analysis is continued by weighting the factors that influence landslides and ground motion and then overlaying the five controlling factor maps (with their respective weight values) to produce a landslides and ground movement vulnerability level map which is then inputted into WebGIS. This map can then be used by local governments and the public as an information medium to support disaster mitigation activities.

Wildfires as a Weathering Agent of Carbonate Rocks

While most of the scientific effort regarding wildfires has predominantly focused on fire effects on vegetation and soils, the role of fire as an essential weathering agent has been largely overlooked. This study aims to evaluate rock decay processes during wildfires, in relation to ground temperatures and rock morphologies of limestone, dolomite, and chalk. In 2010, a major forest fire in Israel caused massive destruction of the exposed rocks and accelerated rock weathering over the burned slopes. While a detailed description of the bedrock exfoliation phenomenon was previously reported, here, we conducted an experimental open fire to determine the temperature and gradients responsible for boulder shattering. The results show ground temperatures of 700 °C after 5 min from ignition, while the peak temperature (880 °C) was reached after 9 min. Temperature gradients show a rapid increase during the first 5 min (136 °C/min), moderate increase during the next 4 min (43 °C/min), and slow decrease for the next 9 min (25 °C/min). After 12 min, all boulders of all formations were cracked or completely shattered. The behaviour of carbonate rocks upon heating was studied to identify the erosive effects of fire, namely the formation of new cracks and matrix deterioration.

Investigation of Deformation Pattern and Movement Law of the Huge-Thick Conglomerate Stratum by a Large-Scale 3D Model Test with Distributed Optical Fiber Sensor Monitoring.

Mining activities under the circumstances of huge-thick stratum occurrence commonly result in dynamic response of the working face. It is crucial to understand the rock failure and movement of the huge-thick stratum in order to prevent dynamic hazards. This paper introduces distributed optical fiber sensor (DOFS) monitoring into a large-scale model test to investigate the deformation pattern and movement law of the huge-thick conglomerate (HTC); the monitoring results are verified by numerical simulation. The results indicate that DOFS monitoring captures the spatiotemporal evolution of zoning development in the overburden deformation. The deformation field of HTC is illustrated, and there exists a strain basin that can be used to estimate the movement law of HTC. The average strain variability Ex, a new homogenization index for characterizing the overburden deformation, is proposed to describe the broken rules of the HTC. The numerical simulation proves the feasibility of the DOFS monitoring method and the correctness of the deformation pattern and movement law. This study provides efficient methods for DOFS monitoring utilization to investigate mining engineering problems and could be beneficial for unearthing the mechanisms of deep ground rock deformation.

Rock magnetic study of grave infill as a key to understanding magnetic anomalies on burial ground

AbstractMagnetic prospecting of burial grounds is still a great challenge in the field of archaeological geophysics. Some graves appear as positive anomalies, whereas others do not generate any traces or even show up by negative anomalies. This study involves ground magnetic survey, rock magnetic and magnetic mineralogy examinations of soils to determine factors responsible for the formation of magnetic anomalies on Late Roman time burial grounds of Chernyakhiv–Sântana de Mureş archaeological culture located in the forest‐steppe of Ukraine. We surveyed these sites by a total magnetic field caesium magnetometer in order to target the archaeological excavations. We sampled infill from graves excavated under positive anomalies and profiles of background soils to analyse the enhancement of induced and remanent magnetization. In the laboratory, we examined magnetic mineralogy and measured various magnetic parameters and ratios characterizing concentration and granulometry of ferrimagnetic phase of soils. For further explanations of the magnetic anomalies, we created 3D synthetic magnetic models of the studied objects and compared the calculated total field anomalies with field measurements by their intensity and size. Here, we show how positive magnetic anomalies of destroyed burials are generated when a destruction pit remains open and later topsoil material gradually refilled it with aid of precipitation water. In this case, the infill layers acquire detrital remanence of the same intensity as the topsoil. Such burials are the best targets for magnetic survey. However, archaeological excavations revealed both intact and destroyed inhumations that caused no magnetic disturbance. Obviously, they were refilled immediately after digging/destruction, so that natural remanence of the infill remains mechanically destroyed. The study of this specific category of archaeological monuments brought us closer in the understanding the formation of magnetic anomalies in soil‐filled features and showed the potential and limitations of magnetic prospection.