The effect of high temperature on engineering properties of rocks has recently become an important topic for geotechnical engineering applications due to the development in geothermal energy extraction, underground coal gasification, disposal of nuclear waste and deep mining applications. This study aims to investigate the engineering properties of four rocks heated at high temperatures and to identify

The existence of a deep borehole in the Earth’s crust disturbs the local stresses and creates a stress concentration that may result in breakout and damage to the borehole. Maintaining wellbore integrity mitigates environmental impacts such as groundwater contamination, gas leakage to the atmosphere, and fluid spills and seepage at the surface. In this paper, the stability of deep boreholes (5 km)

A simulation was performed of the electromagnetic fields response to different unconventional reservoir scenarios and transmitter to receiver configuration, including strong anisotropy, combination of anisotropies and geometries, and larger monitoring times than conventional ones. The approximate solution of the anisotropic Maxwell equations was obtained using a mixed finite element method, discretized

A large fault fracture zone with about 100 m wide exists in Wuyue Pumped Storage Power station of China, where the low-strength and highly-fractured granite severely restricts the stability of the underground powerhouse. However, no relevant exploration has been made on its lithology to ensure the safety of the upcoming construction. To overcome this insufficiency, we present the most recent researches

The dynamic behaviors of calcareous sand were investigated under undrained conditions using cyclic triaxial tests, and the results were compared with those of commercially available Fujian (Fj) sand. The test results were used to evaluate the effects of gradation, particle crushing, and other parameters on the liquefaction resistance. The results of the undrained cyclic triaxial tests indicate that

A gravel cushion is an effective method for preventing rockfall disasters, but the thickness and particle size of cushion influence the impact response between rockfall and cushion. Based on previous indoor experiments, a numerical model of a rockfall impacting a cushion was built, and the accuracy of the model were verified by comparing with the coefficient of restitution obtained from experimental

During infrastructure construction and resource exploitation, the stability analysis of the working face and the determination of the limit support pressure are important. Herein, an improved wedge-prism model is proposed with consideration of three aspects. The inter-slice vertical force expression at any depth in the prism is derived using the slice method, and the vertical force acting on the wedge

In situ capture of crack network evolution is extremely difficult but necessary in fundamental research on mining mechanics and coalbed methane extraction. Systematic field monitoring of the mining-induced crack networks near three mining faces with vertical depths of 700 m, 850 m, and 1100 m in the Pingdingshan coal mine in China was conducted. By utilizing fractal geometry and an algorithm that predicts

Mastering the damage evolution and gas–solid coupling behaviours of coal containing gas allows for the in depth recognition of underlying coal and gas outburst mechanisms. In the current study, we derive an expression for the damage factor of coal containing gas based on the theory of energy conservation to monitor the evolution law of the damage factor during the entire stress–strain process. Under

To investigate the connection and bifurcation problems of the propagation principle and behavior in the whole process of rock crack, bulk insert of cohesive elements between entity elements has been developed. First, it defines what kind of cohesive element is best to be inserted between the model elements. To minimize the influence of embedded cohesive elements on the overall stiffness, Kcohesive

Intermediate geotechnical materials such as Victorian Brown Coal (VBC) often exhibit complex fracture characteristics due to the interplay of ductile and brittle behaviour. A diverse set of in situ joint orientations and fracture characteristics are found in the open-cut mines of the Latrobe Valley, Victoria, Australia. As such, the propagation of pre-existing discontinuities plays a significant role

As an emerging numerical calculation method, the numerical manifold method (NMM) has incomparable advantage in solving continuous and discontinuous deformation problems in a unified framework. In this study, an improved numerical manifold method was deployed to solve the crack propagation and coalescence problem with cracking friction effect in fractured rock mass. Firstly, based on the basic theory

The stability of slopes directly affects human lives, the environment, and the economy. Inaccurate geological profiles within numerical slope stability models can lead to potentially catastrophic consequences when model conditions do not appropriately reflect real-life stratigraphy. In cases where localised deposits are prevalent, probabilistic methods are often necessary to accommodate for unknown

Multiple hydraulic fracturing treatment from horizontal wells has been widely used to enhance the productivity of unconventional hydrocarbons. Interaction among the fractures can cause the reorientation of fractures and lower the stimulation efficiency. We perform discrete element method (DEM) simulations to assess the influence of completion scheme on the trajectory and efficiency of fractures si

Selective breakdown of mineralized particles by using high-voltage pulses (HVP) has been reported, yet its mechanisms are not fully understood, and the HVP setting factors affecting its efficacy in ore pre-concentration for the mining industry are not established. This study investigates the electro-dynamic mechanisms of electric breakdown by using the time-transient dielectric breakdown model and

Hard roof fracturing characteristics and mining-induced stress behaviors can be studied to ensure production safety in top coal caving face. Field tests were conducted at top coal caving face No. 8309 in the Tongxin mine of the Datong Coal Mining Group in China. The monitoring results indicated two modes of periodic weighting: short weighting steps with low intensity and long weighting steps with high

The determination of the gray threshold is crucial for the quantitative characterization of digital images. In this study, a new algorithm is proposed to determine the optimal image segmentation threshold. This algorithm is based on a combined analysis of the gray distribution curve and its second differential distribution curve of the digital image. Then, the feasibility and accuracy of the Liu–Cao

The dynamic mechanical behavior of jointed rock mass plays a key role in the blasting excavation from mining and tunneling engineering. To investigate the influence of joint parameters (e.g., joint length, joint position and joint type) on the mechanical behavior of singly-jointed samples, dynamic impact compression tests are performed on prefabricated rock-like samples using the Split Hopkinson Pressure

The mechanical properties and permeability of shales after supercritical carbon dioxide (SC-CO2) imbibition are vital to shale gas production and CO2 sequestration in shale reservoirs. In this study, triaxial compressive strength tests, steady state permeability tests, and CT scanning tests are performed on shale samples with 30 days of SC-CO2 imbibition. The results show that minerals dissolution

The mesoscopic parameters of numerical simulation cannot be directly obtained from laboratory test, and it is necessary to calibrate the parameters by comparing the numerical simulation results with the experimental results. To quickly and reasonably determine the mesoscopic parameters of limestone, a unique variable principle is used to comprehensively analyze the quantitative relationship between

Supercritical carbon dioxide (SC-CO2) jet is a promising technology for the extraction of coalbed methane. As a key component in the process of jet formation, the nozzle is an essential factor affecting the efficiency with which an SC-CO2 jet breaks coal and rock. The nozzle structure directly affects the energy conversion rate and flow field structure of the jet. Thus, the use of a suitable nozzle

Low cutting rate and high tool wear are the important problems during excavating hard rocks. In order to find a solution for these problems, some investigations have been carried out by several researchers. One of the recent studies is the microwave assisted excavation of hard rocks. Revealing the impacts of microwave exposure on the minerals and micro-structures of rocks will be useful for the investigations

For more than seven decades, the impounding of artificial water reservoirs has been known to trigger earthquakes. Accordingly, reservoir-induced seismicity (RIS) has been studied in terms of its identification and mechanisms. In this paper, we report three laboratory experiments to investigate the effects of water impoundment and pore-pressure diffusion on the reactivation of faults in high tectonic

Carbon sequestration involves long-term containment of CO2 in ideally sealed reservoirs. However, CO2 migration can weaken rocks and faults by geochemical alteration, elevate risks of seismic hazards, and loss of inventory. Recent studies show that CO2 bleaching can alter the iron oxide grain coating of sand-sized quartz in sandstones, which may impose a significant influence on frictional stability

This study designs and introduces an X-ray-compatible thermo-hydro-mechanical coupling triaxial device. The functional parameters of this device included a confining pressure, axial force, injected fluid pressure, and temperature up to 20 MPa, 400 kN, 10 MPa, and 100 °C, respectively. Triaxial stress loading–unloading cycles and permeability experiments for coal specimens were carried out using this

The factors controlling the migration and enrichment of iron in Archean banded iron formations are important for understanding the formation of iron ore resources. Here we present, for the first time, a micro-three-dimensional modeling method that can be applied to hand specimens of iron ores. This method and petrographic observations, electron probe microanalysis, and the structural deformation characteristics

The macroscopic deformation process of rock is the external performance of microscopic damage in essence, and research from the macro and micro perspectives can effectively reveal the failure mechanism of rock. To further investigate the fracture behaviors of yellow sandstone disc specimens under different loading rates, seven groups of Brazilian disc splitting tests with different loading rates from

Nanoindentation has become an increasingly popular method to determine the mechanical properties of both homogeneous and heterogeneous materials. Rocks are inherently heterogeneous and understanding their mechanical properties is of vital importance for relevant engineering applications. Due to its high precision and resolution in both force and displacement, nanoindentation can be utilized to extract

Due to the spatial variability of material characterisations in deep and large scale excavations, stability assessment is often a challenging task. Numerous slope stability analysis methods based on a range of assumptions and principles are implemented in commercial software packages to ease the process of stability assessment of non-homogeneous and multi-layered slopes. However, the selection of a

Numerical simulation of fracture propagation during hydraulic fracturing is performed based on the extended finite element method. The influences of existing natural fractures and beddings on the formation of fracture network are focused. It is shown that the hydraulic fracture network in the case of random distribution for natural fracture is more conducive to form than that in the case of the regular

In underground engineering practice, the surrounding rocks are subjected to a nonuniform stress field with various radial gradients. In this study, a series of conventional triaxial repetitive impact tests using hollow cylindrical sandstone (HOS) specimens were conducted to reveal the impact waveform features and failure properties of rocks under nonuniform stress conditions. The tests were conducted

A rheological constitutive model for damaged zone evolution of a tunnel is proposed in this paper to describe the strain hardening and softening properties of the excavation-disturbed rock mass. Firstly, the one-dimension rheological model is introduced by connecting the improved St. Venant body with the Nishihara model, and this model can be used to describe the whole process including transient viscoplastic

With the development of carbon dioxide sequestration, the influence of carbon dioxide on coal properties has been paid more and more attention by experts and scholars. Scanning electron microscopy was employed to observe the three-point bending characteristics of bituminous coals treated with or without carbon dioxide gas. The experimental results showed that the carbon dioxide gas treatment had obvious

To evaluate the safety conditions and deformation characteristics of the cemented tailings backfill (CTB) mining disturbed area near shafts of Taohuazui Gold Mine in China, an analytic hierarchy process—fuzzy comprehensive evaluation (AHP-FCE) model for disturbance degree and safety evaluation of backfill mining was established, the historical and current backfill mining processes were simulated based

Pressure-relief mining is the primary method to remove gas and coal outbursts and realize coal and gas simultaneous extraction in deep, high-gas, and low-permeability coal seams. Numerical modeling has been widely used to evaluate the effectiveness of protective coal seam (PCS) longwall mining, which usually employs experiment-derived permeability models to describe permeability changes and coalbed

A wide range of alternatives is available to design a support system to stabilize an underground opening under squeezing conditions. An underground mine development was selected for the research where the underground openings reach to a depth of 1000 m and weak geological formations are present. The operational concerns in the mine development led to a shaft support design having a thick reinforced

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Thermal conductivity is a key parameter for many soil applications, especially for dimensioning shallow and very shallow geothermal systems based on the possible heat extraction rate and for modelling heat transfer processes around high voltage underground cables. Due to the limited purview of direct thermal conductivity measurements, for an investigation of extensive areas, usually other geophysical

The brittleness of rocks plays an important role in the fracture network fracturing process of unconventional oil and gas reservoirs, the drilling efficiency of rock breaking and wall stability, and mining engineering. Rock brittleness has become one of the key parameters in the study of many rock mechanics and related engineering problems. However, there is still no widely accepted definition of brittleness

In the framework of a \({{\hbox {CO}}}_{2}\) storage feasibility study, we evaluate porosity and permeability of shale formations constituting the overburden of a hydrocarbon reservoir, where the gas is stored. These properties are required to perform fluid-flow simulations and analyze possible leakages from the reservoir to the surface. In this process, calibration with well logs is essential. Standard

Radial drilling hydraulic fracturing has become a new stimulation method. The hydraulic fracturing effect of radial drilling on site is not ideal, and the stimulation effect of some wells is not obvious. The hydraulic fracturing effect of radial drilling is closely related to the crack initiation position after radial drilling fracturing. In the past researches on fracture initiation in radial drilling

Geothermal resource quantification requires underground temperature and volume information, which can be challenging to accurately assess at the regional scale. The analytical solution for steady-state heat conduction with internal heat generation is often used to calculate temperature at depth, while geological models can provide volume information. Both approaches were originally combined in a single

To describe the mechanical behavior of interfaces existing in rocks, a three-dimensional contact element model with a certain thickness was proposed that could simultaneously consider the heterogeneity, damage evolution and state variation of interfaces. The Weibull distribution function was employed to describe the rock heterogeneity. The damage evolution of the contact element was analyzed by using

This study prepared transversely isotropic rock-like specimens in three groups of layer thickness ratios, alternating with two kinds of rock-like materials. The conventional triaxial compression tests confirm mechanical difference of the two rock-like materials. The velocities of ultrasonic wave (longitudinal wave VP) are measured for each transversely isotropic rock-like specimen before uniaxial compressive

With the development of deep energy resources, understanding variations in the physical and mechanical properties of rocks at different depths is significant. In this paper, core samples from ten different burial depths (1000 m, 1300 m, 1600 m, 1850 m, 2600 m, 3500 m, 4800 m, 5100 m, 5600 m, and 6400 m) were collected from the Songke No. 2 (SK-2) well and the Daqing Oilfield. To the best of our knowledge

Permeability and meso-structure evolution of coal are crucially important to the profound understanding of coal–gas interactions in the enhanced coalbed methane recovery and in controlling gas outburst. Very few studies focus on the effect time has on these interactions We performed a series of experiments on the permeability evolution of coking coal subjected to the long-term exposure of triaxial

Fluid flow through rock media is highly significant in underground water management, the geothermal recovery process, and various underground engineering applications. Fractures have a critical effect on the fluid flow through low-permeability rocks since they serve as the major flow channels in the rock formation. Consequently, the evaluation of fracture permeability is crucial to many engineering

Blasting operations create significant problems to residential and other structures located in the close proximity of the mines. Blast vibration is one of the most crucial nuisances of blasting, which should be accurately estimated to minimize its effect. In this paper, an attempt has been made to apply various models to predict ground vibrations due to mine blasting. To fulfill this aim, 112 blast

The rational choice of perforation arrangement and injection angle is of great significance to improve the efficiency of synchronous fracturing and to achieve the stimulation of the shale reservoir. In this paper, the influence of perforation angle and perforation arrangement on the crack propagation mechanism and rock failure mode of synchronous fracturing is studied based on the particle discrete

The characteristics of the particle size distribution (PSD) are an important reflection of energy consumption during rock drilling and drilling efficiency. A new approach incorporating both fine and coarse fractions of the PSD to supplement the typical approach of merely utilizing D50 (50% passing diameter) to index drilling resistance and efficiency is reported in this paper. A series of drilling

Main factors influencing the wide range of apertures (from 50 to 400 mm) of mining-induced horizontal fractures (Torezko-Snezhnyanskaya coal area, Ukraine) at traditional (without grout injection into bed separation) longwall coal mining were analysed. Apertures of these fractures were directly measured (using an original experimental device) in vertical boreholes drilled from ground surface to active

Safe mining depth constitutes the key to the open-pit mine development, it is significant to research the safe mining depth. First, According to the field geological investigation and geophysical exploration, the existing landslides were summarized and analyzed to obtain the potential destabilization and failure modes in mine, which laid the effective reference for the slope stability analysis in the

Acoustic transmission along the drill string for measurement while drilling (MWD) is an effective solution to the problem of the low transmission rate that results from mud pulse transmission. However, the actual downhole acoustic waves are affected by many factors, such as drilling fluid properties and, formation boundaries, and their effects on acoustic wave transmission in drill string are not thoroughly

Many large engineering projects, e.g., the Sichuan–Tibet Railway, inevitably cross the earthquake active areas and the geology complicated zones, facing the challenges of dynamic disturbances and disasters. In view of this, the conceptualization of engineering disturbed rock dynamics is proposed in this paper, aiming to systematically study the rock dynamic behavior and response subjected to engineering

The classification of rock slopes and the determination of rock extent are essential for slope stability analysis. At present, the efficiency of artificial methods is low and affected by subjective factors. A convolution neural network model for rock slope image analysis is established based on the Tensorflow. 80,000 rock slope images are extracted and compressed using convolution and pooling. Then

In an enhanced geothermal system (EGS), fractures and fracture networks are the predominant elements for fluid flow and heat transfer through the artificial reservoir. In this work, different conceptual discrete fracture networks were generated by characterizing the fracture number, fracture bifurcation and fracture connectivity of the fracturing area. A thermal–hydraulic (TH) coupled mathematical

Understanding the consequences of mining is most important in order to prevent negative outcomes for the environment as natural systems are used by humans for agriculture/silviculture. The present manuscript deals with the impact of subsidence due to underground coal mining on native soil. Depth-wise changes in soil texture and nutrient components in four layers; 0–15 cm, 16–30 cm, 31–45 cm and 46–60 cm

In recent studies, the links between hydrocarbon accumulations and gold mineralizations have been examined. According to the results obtained from these studies, it has been reported that gold and hydrocarbons are carried and deposited by the same hydrothermal fluids. In the Seferihisar Uplift, the Efemçukuru Gold Operation possesses the largest proven gold reserves of Turkey. For this reason, in this

The determination of deformation parameters of rock material is an essential part of any design in rock mechanics. The goal of this paper is to show, that there is a relationship between static and dynamic modulus of elasticity (E), modulus of rigidity (G) and bulk modulus (K). For this purpose, different data on igneous, sedimentary and metamorphic rocks, all of which are widely used as construction