Physical Sciences and Mathematics Commons^™

Editorial For The Special Issue “Advances And Applications Of Polymer Gels For Subsurface Energy And Storage”, Baojun Bai, Jingyang Pu

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Polymer gels are essential functional materials for subsurface energy operations, playing a critical role in conformance control, fluid diversion, hydraulic fracturing, and leakage mitigation. As reservoirs become increasingly complex and the demand for sustainable energy grows, continued innovation in gel technologies is crucial. This editorial introduces a Special Issue titled "Advances and Applications of Polymer Gels for Subsurface Energy and Storage," which compiles seven original research articles exploring recent developments in gel synthesis, characterization, and applications. The featured studies highlight the versatility of polymer gels, including nanoparticle-reinforced composites, foam–gel hybrids, recrosslinkable preformed particle gels, and advanced fracturing fluids. The contributions …

The Sliding Aperture Transform: A Mathematical Method Applied To Radiation-Induced Dlts Capacitance Transients, Md Abu Bakkar Siddique

Graduate Masters Theses

This thesis presents the Sliding Aperture Transform (SLAPt), a novel mathematical technique for extracting exponential argument and pre-factor  from experimental data. The method transforms measured waveforms into an inverse-domain representation where exponential decay processes appear as distinct peaks, simplifying data analysis and reducing the effects of baseline offsets and noise. The technique is here applied to time dependent capacitance transients associated with irradiated and non-irradiated silicon pn junction diodes. The technique is further developed and applied to positive argument exponentials using an axillary function. This allows forward bias  current-voltage measurements, and forward pulse-bias current transient measurements to be SLAP analyzed, …

Motor Imagery Eeg Decoding For Brain-Computer Interfaces: Structured Representation, Transfer, And Drift, Yiming Shen

Graduate Doctoral Dissertations

Motor imagery EEG decoding is often summarized by the accuracy of a final classifier, but the classifier is only the last stage of the pipeline. Before classification, the signal has already been shaped by preprocessing, feature extraction, source-session organization, and adaptation. This dissertation studies how feature representation, source-session transfer, and drift shape reliable MI-EEG decoding for brain-computer interfaces.

It first studies within-session decoding on public MI-EEG datasets using nested validation that keeps preprocessing, feature fitting, and model selection inside the training folds. This analysis separates gains from feature representation from gains due to nonlinear classification, and relates both comparisons to …

Analysis Of The Throttle Settings Under Uncertain Information, Latafat Gardashova, Nihad Afandi

Chemical Technology, Control and Management

Although classical fuzzy logic controllers are capable of modelling non-linear control systems, they fail to consider the reliability of linguistic information, sensor measurements, and expert knowledge. In this paper, an intelligent controller based on the use of Z-numbers is developed for steam-turbine throttle control. Linguistic information and its confidence degree are considered simultaneously in such a controller. The temperature and pressure values are taken as input variables, while the throttle rotation is selected as the controller output variable. At first, the Z-number representation system is constructed to include the credibility of linguistic measurements and control rules. Then, a Mamdani Type-1 …

Nonlinear System Identification Based On Fuzzy Radial Basis Neural Network With Multi-Connected Weight Connections, Kabul Khudaybergenov

Chemical Technology, Control and Management

This paper builds on our earlier radial basis function network with multiple connections (RBFMC) by placing it within a fuzzy inference framework for nonlinear system identification. The idea is inspired by the diversity of neurotransmitters found in biological neurons: instead of a single hidden-to-output weight, RBFMC gives each hidden unit a multi-dimensional connection whose components act as independent filters. Once fuzzy logic is added, each hidden neuron becomes a fuzzy rule, and its antecedent is built from several Gaussian membership functions, one per connection. The resulting Fuzzy RBFMC produces an interpretable, multi-filter description of local regions of the input space …

Neural Network Driven By Electrochemical Performance Data For Predicting The Discharge Termination Time Of Seawater Electrolyte-Based Metal-Air Batteries, Peng-Peng Shen, Yi-Chi Pan, Yu-Rong Liu, Lu-Dan Zhang, Ning Niu, Guan-Jun Wang, De-Kun Yang, Xin-Long Tian, Peng Rao

Journal of Electrochemistry

Seawater electrolyte-based metal-air batteries exhibit great promise for marine energy supply systems. However, conventional statistical analysis methods, though applicable to seawater metal-air battery lifetime prediction, have inherent limitations of insufficient prediction accuracy and large error. Herein, a deep time-series regression framework based on InceptionTime and incorporating prior-biased attention pooling is proposed to construct a nonlinear mapping between electrochemical performance sequences and the discharge termination time of catalysts. Specifically, chronoamperometric profiles are employed to extract long-term stability features, while prior knowledge derived from linear sweep voltammetry is introduced to strengthen the attention weighting over critical potential regions. Under a nested leave-one-catalyst-out …

Microwave-Assisted Synthesis Of Core-Shell Structured Pd@Pdptcufe Recessed Truncated Octahedral Nanocrystals For Multifunctional Electrocatalysis, De-Zhong Hu, Wen-Dan Jiang, Wei Keat Ng, Jun Yang, Xiong-Wu Kang

Journal of Electrochemistry

Developing cost-efficient and durable multifunctional electrocatalysts of hydrogen evolution reaction, oxygen reduction reaction and oxygen evolution reaction is crucial for improving energy conversion efficiency in electrolytic water splitting electrolyzer and advancing rechargeable zinc-air batteries. Polyhedral shaped nanocrystals with well-defined crystal facets represent a type of model catalysts that enables the exploration of structure-activity relationships. However, it is still very challenging to prepare alloy nanocrystals with multiple metal components due to their complicated redox potentials and mixing enthalpy. Herein, we report a rapid microwave-assisted polyol reduction method for syntheses of core-shell Pd@PdPtCu, Pd@PdPtCuNi, Pd@PdPtCuCo and Pd@PdPtCuZn octahedral nanocrystals, and recessed truncated-octahedral …

In Situ Electrochemical Characterization Techniques For Active Hydrogen In Electrocatalytic Nitrate Reduction To Ammonia, Hong-Mei Li, Mei Yi, Zhao-Yu Jin, Ming-Hao Xie, Khalid M. Omer, Yong Guo, Pan-Pan Li

Journal of Electrochemistry

Electrocatalytic nitrate reduction to ammonia (NitRR) represents a sustainable pathway that integrates environmental remediation with the production of high-value ammonia. However, the activity and selectivity of this process are limited by the generation, consumption, and dynamic equilibrium of the key transient intermediate—active hydrogen (*H). Precise modulation of *H necessitates a comprehensive understanding of its behavior, which relies fundamentally on advanced in situ electrochemical characterization techniques. However, a systematic review dedicated to the rational selection and application of in situ electrochemical techniques for the specific characterization of *H in NitRR, with clear definitions of each technique's "detectable targets, quantitative accuracy, and …

Modeling Of Supersonic Wave And Shock Propagation Using The Lattice Boltzmann Method, Timothy P. Schroeder

Beyond: Undergraduate Research Journal

The lattice Boltzmann method (LBM) has emerged as a mesoscopic alternative to traditional Navier-Stokes solvers for modeling fluid dynamics offering advantages in computational efficiency, parallelization, and handling of complex boundaries. Despite these strengths, accurately reproducing compressible, shock-driven phenomena remains challenging. This study investigates the performance of LBM in simulating the Sod shock tube problem, a classical benchmark for compressible flow-using both single and double distribution function formulations across one- and two-dimensional lattice stencils. A MATLAB-based solver was developed to model the flow under isothermal conditions and compared to the analytical solution using the L2 norm error. The one-dimensional models achieved …

Table Of Contents, The Editors

Coal Geology & Exploration

No abstract provided.

Resilience-Oriented Geological Safeguards For Damage Mitigation In Coal Resource Exploitation, Wang Shuangming, Sun Qiang, Yan Meixin, Miao Lintian, Liu Lang, Qiao Junwei, Niu Chao, Geng Jishi, Fang Chenxi, Zhang He, Xiao Lele, Li Shibo

Coal Geology & Exploration

Background Coal remains a fundamental component of China’s energy security system. With the westward shift of coal development and continuous expansion into deeper strata, coal mining is confronted with increasingly complex geological conditions and growing ecological constraints. Geological damage induced by mining disturbance has evolved from isolated geological issues into a coupled Earth-system problem involving the lithosphere, hydrosphere, pedosphere, atmosphere, and biosphere, characterized by uncertainty, hysteresis, concealment, and cross-scale accumulation. Resilience-based damage mitigation emphasizes reducing the probability, intensity, and recovery costs of geological damage through proactive identification, dynamic regulation, damage suppression, and post-disturbance restoration under mining disturbance and external environmental …

Mechanisms And Implications Of The Novel Cast Model Of Coal Graphitization, Wang Shaoqing, Zhang Jingzhe, Zhang Xiaomei, Wang Xiaoshuai, Chen Hao, Wang Xiaoling, Li Wu, Tang Yuegang

Coal Geology & Exploration

Objective and Methods Coal graphitization is a multi-stage process with abrupt changes rather than linear evolution. So far, its inherent driving mechanisms have not yet been fully elucidated. Notably, twisted graphene was observed in the process of coal graphitization in 2025, providing a new opportunity to reveal the essence of this structural transformation. Results and Conclusions By combining previous research results, this study proposes a novel coal graphitization model that consists of condensation, alignment, stacking, and twisting (CAST). The four parts of the CAST model are organically integrated, collectively forming a continuous and dynamic evolutionary process. Most especially, no absolute …

Spatial Topological Configurations Of Cleats And Geometrical Quantitative Characterization Of Matrix Blocks In Deep Coal Seams, Shen Jian, Li Wei, Tian Yongjing, Ma Tianyu, Zhang Hewei, Dong Jiying, Zhu Peipei

Coal Geology & Exploration

Objective Cleats in deep coal seams are characterized by strong heterogeneity, and their topological configurations, as well as their topological relationships with matrix blocks, remain poorly understood. On the other hand, the assumptions regarding the size and geometry of matrix blocks adopted in representative reservoir structure models and numerical simulations do not fully reflect actual reservoir conditions. Methods Deep coal cores collected from the northeastern Ordos Basin were investigated in this study. Using CT scanning and topological theory, a multi-dimensional topological parameter system was established to characterize cleats in deep coal seams. Furthermore, four topological configurations of cleats in deep …

Stable Isotope-Based Origin Identification And Enrichment Zone Division Of Medium- To Low-Rank Coalbed Methane, Wang Qiong, Xu Fengyin, Ren Pengfei, Xu Hao, Lu Pengda, Hu Han, Zhou Siyuan

Coal Geology & Exploration

Objective Medium-to low-rank coalbed methane (CBM) exhibits complex origins with significant vertical differentiation, leading to unclear origin identification and enrichment patterns. This study aims to determine the genetic mechanisms, enrichment patterns, and efficient exploitation pathways of medium- to low-rank CBM. This will help improve the theoretical system for the exploration and exploitation of such CBM. Methods CBM data from 14 typical low- to medium-rank coalfields and coal-bearing basins across the world were comprehensively analyzed, including CBM compositions C₁/(C₂+C₃), carbon and hydrogen isotopes of CH₄ (δ¹³C-CH₄ and δD-CH_{4 …}

Dynamic-To-Static Elastic Parameter Conversion Models For Coals Under Temperature-Pressure Coupling: A Case Study Of The No. 8 Coal Seam In The Daning-Jixian Block, Zhang Wei, Wu Peng, Liu Conghui, Zhang Sidun, Sun Xuedong, Yang Haixing, Ma Zhuang, Shi Rui, Shen Jian

Coal Geology & Exploration

Objective Existing dynamic-to-static elastic parameter conversion models for coals fail to fully account for the actual in situ pressure and temperature conditions of deep reservoirs. This leads to significant deviations in directly evaluating the mechanical properties of reservoirs using log-derived dynamic parameters. To address this challenge, this study investigated dynamic-to-static elastic parameter conversion under the in situ stress and geotemperature conditions of strata. Accordingly, high-precision parameter conversion models were established. Methods This study examined coal samples from the No. 8 coal seam at a burial depth of approximately 1200 m in the Daning-Jixian block along the eastern margin of the …

A Geochemical Evaluation Method For Geological Sweet Spots Of Marine-Continental Transitional Shale Gas: A Case Study Of The Shan$^3_2 $ Sub-Member, Eastern Margin Of The Ordos Basin, Zhu Xingcheng, Li Yong, Lu Jungang, He Qingbo, Li Shuxin, Xiao Zhenglu, Li Xiang, Jiang Qijun

Coal Geology & Exploration

Background China boasts abundant marine-continental transitional shale gas resources. However, marine-continental transitional shales in the country exhibit complex geological conditions characterized by rapid lateral facies transition, vertical superimposition of multiple lithologies, and small single-layer thickness. These characteristics pose a challenge to shale gas sweet spot prediction. Therefore, establishing a sweet spot grading and evaluation system tailored to these shales is of great significance for guiding decision-making in hydrocarbon exploration and supporting large-scale production. Methods Based on core observations, this study systematically evaluated the geochemical characteristics of marine-continental transitional shales in the 3rd submember of the 2nd member of the Permian …

An Integrated Automated Parameter Optimization Method Based On Fdem And Isight For Rock Mass Engineering: A Case Study Of Pillar Stability Design, Zhu Defu, Gao Bolong, Xu Jiabo, Wang Deyu, Gao Peng, Li Yalin, Hu Wenshuo

Coal Geology & Exploration

Background Conventional rock mass engineering design largely relies on empirical equations or numerical simulation schemes selected from a limited number of comparable cases, making it difficult to effectively balance multiple constraints such as safety, economic viability, and resource recovery. The finite-discrete element method (FDEM) based on the intrinsic cohesive zone model (ICZM) can effectively simulate the evolution of quasi-brittle materials from continuous to discontinuous behavior, rendering it particularly suitable for engineering issues involving highly discontinuous rock masses. Therefore, FDEM has become an important numerical analysis method in rock mass engineering. However, there remains an urgent need for a high-precision, integrated, …

Selection And Verification Of Optimal Key Parameters Of Ultra-Wideband Radars For Life Detection In Coal-Rock Shielding Environments In Coal Mines, Huang Yuan, Zheng Xuezhao, Wen Hu, Jin Feiyang, Xu Chengyu, Liu Yin, Ding Wen

Coal Geology & Exploration

Objective and Methods Ultra-wideband (UWB) radars can transmit electromagnetic waves that penetrate coal and rock media, thereby addressing the challenge of detecting and localizing personnel trapped in shielding environments during mine collapse. However, key parameters for UWB radar detection are difficult to determine due to complex mine environments, diverse media, and unclear dispersion characteristics. To deal with this issue, this study determined the frequency-dependent dielectric properties of various coal and rock media, as well as human tissues, through experiments and fitting. In combination with actual rescue scenarios, this study established the electromagnetic equivalent model of shielding environments in coal mines. …

Factors Influencing The Build-Up Rate Of Small-Diameter Rotary Steerable Systems In Underground Coal Mines, Yang Dongdong, Li Quanxin, Zhang Youzhen, Chen Long, Chu Zhiwei, Jiang Bici, Wang Bo, Yan Wenchao

Coal Geology & Exploration

Objective Intelligent drilling represents an important part of intelligent coal mine construction. However, measurement-while-drilling (MWD) directional drilling, the core of underground intelligent drilling operations, currently suffers from several limitations, including the high dogleg severity of wellbore trajectories, low drilling efficiency, and poor hard-rock penetration. Rotary steerable system (RSS) technology has emerged as a key approach to addressing these limitations owing to its high-precision control on drilling trajectories. Methods This study systematically analyzed the factors influencing the build-up rate of small-diameter, push-the-bit RSSs using a modified 3-point circle method and the longitudinal beam bending method. Through theoretical modeling, the coupled impacts …

Machine Learning-Based Diagnosis Of Fracture-Induced Lost Circulation And Intelligent Selection Of Lost Circulation Control Fluids, Sun Huan, Zhu Mingming, Wang Jinshu, Yao Lu, Zhou Fangfang, Tan Xuebin, Sun Yan, Qu Yanping, Chen Ning

Coal Geology & Exploration

Objective and Method Drilling operations in the Changqing area face several challenges in lost circulation, including complex types, significantly different characteristics, and difficulty in designing plugging formulations. To address these issues, this study proposes a DSX-Hybrid coupled intelligent decision-making framework, which serves as an integrated scheme to identify lost circulation channels, perform intelligent selection of plugging formulations, and offer recommendations on construction process. In this framework, given the scarcity of labeled log data, the density-based spatial clustering of applications with noise (DBSCAN) is employed to mine latent geological characteristics of unlabeled data. Then, the self-attention convolutional neural network (SACNN) is …

Key Technologies And Their Application Of Vertical Large Models For Geological Guarantee In Coal Mining, Liu Zaibin, Fan Tao, Liu Borui, Chen Changyuan, Li Guihong, Li Wei, Jing Xiaotian, Li Xiping, Du Yiming

Coal Geology & Exploration

Background General-purpose large language models (LLMs) have remarkable capabilities in natural language understanding and complex-task reasoning. However, when applied to geological guarantee in coal mining, these models still suffer from several inherent limitations, including insufficient professional geological knowledge, limited insights into industrial terminology, and inadequate integration of engineering logic and rules. Consequently, they face challenges in accurately capturing domain-specific knowledge and reasoning mechanisms required for geological interpretation, early warning of disasters, and decision-making for disaster prevention and control. These issues lead to limited applicability and reliability of general-purpose LLMs. On the other hand, geological guarantee in coal mining involves multi-source …

Microstructure Evolution Characteristics Of Coal Briquettes During Hot Pressing Carbonization And A Temperature Control Method, Gan Qingqing, Xu Jiang, Peng Shoujian, Cai Guoliang

Coal Geology & Exploration

Objective Coal briquettes used for physical simulations of gas disasters in coal mines generally exhibit low strength and high permeability. To address this challenge, this study developed a new hot pressing process and a temperature control method to optimize the mechanical and seepage performance of coal briquettes. Methods First, an optimal mixing ratio scheme was determined based on the Horsfield close-packing theory, and coal briquettes were prepared at different temperatures using an independently developed hot pressing system. Subsequently, the microstructure evolution patterns of the hot-pressed coal briquettes were characterized using an X-ray diffractometer (XRD), an X-ray photoelectron spectrometer (XPS), a …

3d Geological Modeling And Its Application For Steeply Dipping Coal Seams In The Miquan Area, Xinjiang, Wu Luofei, Li Yong, Zhang Weiqi, Han Yiyang, Zhang Jie, Cao Mingliang, Li Qiang

Coal Geology & Exploration

Background Influenced by multi-stage compression from the North Tianshan and Bogda mountains, the southern margin of the Junggar Basin in Xinjiang exhibits the widespread development of steeply dipping coal seams. The extreme stratigraphic occurrence, combined with complex structural superimposition styles, poses significant challenges to the fine-scale characterization of these coal seams. Correspondingly, the planar and regional distribution patterns of gas content in these coal seams remain poorly understood, rendering it difficult to effectively determine the sweet spots of coalbed methane (CBM). Methods Focusing on the Miquan area, Xinjiang, this study investigated the methodology for 3D geological modeling of representative steeply …

Evolutionary Characteristics And Fine-Scale Zoning Of Overburden Fractures For Pressure-Relief Mining Of Soft Coal Seams, Wang Long, Deng Zhiliang, Zhang Zongxiang, Guo Baohua, Tan Hongchen, Zhao Pengtao, Hu Longsheng

Coal Geology & Exploration

Objective During the mining of coal seam groups, substantial gas is prone to rush into the mining face from adjacent coal seams through interconnected mining-induced fractures. This poses a threat to safe coal mining. Under pressure-relief mining of soft coal seams, their low permeability and high stress sensitivity present challenges to the successive mining of protective and protected coal seams. Specifically, mechanisms behind the overburden fracture evolution remain poorly understood, and it is difficult to identify preferential pathways for gas migration accurately. Methods This study investigated coal seam groups in the Jiahe mining area of Hunan Province as the engineering …

Sources And Occurrence Patterns Of Hydrocarbons In The Surrounding Rocks Of Coal Seams: A Case Study Of The Jurassic Yan'an Formation In The Xinzhuang Mine Field, Longdong Area, Zhang Peng, Chen Dongdong, Zhao Junfeng, Zheng Kaige, Wang Chunxin, Zhou Xingtian

Coal Geology & Exploration

Objective and Methods This study aims to ascertain abnormal hydrocarbon outflows from the surrounding rocks of coal seams in the Jurassic Yan'an Formation within the Xinzhuang mine field in the Longdong area, southwestern Ordos Basin. Based on the fundamental principles of petroleum geology, sedimentology, and coal geology, this study systematically analyzed the sources, occurrence patterns, and primary controlling factors of hydrocarbons in the surrounding rocks of coal seams using methods including core observation, sample analysis, and statistical mapping. Results and Conclusions In the Xinzhuang mine field, hydrocarbon outflows are primarily identified in the floor of the No. 8 coal seam …

Investigating Seepage In Rough Porous Media Fractures Using Fractional Brownian Motion Simulation, Liu Weitao, Kong Debin, Mao Qingfu, Zhao Jiyuan, Gu Yulong, Zhang Xiao

Coal Geology & Exploration

Background Natural rock fractures are often partially filled with permeable materials such as silt and minerals under long-term geological and hydraulic actions, forming complex structures containing unfilled voids. The seepage characteristics of such fractures significantly influence petroleum extraction, mine water prevention, and the stability of underground engineering projects. Methods To reveal the underlying seepage mechanisms, this study generated rough profiles of unfilled voids with different fractal dimensions based on Fractional Brownian Motion. A theoretical expression for the overall permeability of partially filled fractures was derived, and a coupled free flow–porous medium flow numerical model was established. This framework was used …

Key Technologies And Engineering Practices For Green Drainage Of The Jurassic Burnt Rock-Hosted Water In The Shenfu Mining Area, Ji Zhongkui, Mou Lin, Wang Hai, Zhu Kaipeng, Zhao Kaixing, Chen Pan, Xue Xiaoyuan, Han Qiang, He Bo, Wang Fuming

Coal Geology & Exploration

Objective In the northern part of Shaanxi Province, coal mining has led to a pronounced contradiction between coal mining and water conservation, along with a serious threat to China’s ecological redline. These challenges necessitate transforming the mine water drainage pattern in coal mines. Green mine water drainage represents a key approach to achieving coordinated coal-water production in areas containing burnt rocks. Methods Focusing on the conservation-oriented utilization of the Jurassic burnt rock-hosted water in a coal mine within the Shenfu mining area, this study explored a solution to coordinated coal-water production in areas affected by burnt rock-hosted water from the …

Mine Water Storage In Deep Strata: Temperature Responses And The Quantitative Identification Of Primary Permeable Intervals, Xue Jiankun, Wang Shuangming, Zhang Pingsong, Wang Xiaodong, Han Le, Wang Zhizhou, Wang Yutong, Wang Zhibo

Coal Geology & Exploration

Background Storage in deep strata represents an effective approach to treating high-salinity mine water in mining areas of western China. For this technology, the use of directional wells can significantly enhance water injection efficiency, while selecting primary permeable intervals with high injectivity as drilling targets is key to its successful implementation. However, the accurate identification of these intervals in deep strata remains challenging. Methods By analyzing the wellbore temperature variations in the injection well during water injection, a qualitative model was developed to evaluate primary permeable intervals based on wellbore temperature curves. Following the principles of momentum and energy conservation, …

Field Tests On The Capillary Barrier Effect Of Covers For Comprehensive Utilization Of Solid Waste In Waste Dumps, Duan Xu, Chen Chuangchuang, Qiu Xun, Wang Bo, Shi Luyu, Yan Hanyang, Zou Yu, Qu Jin, Hu Zhaojiang

Coal Geology & Exploration

Background In the arid and semi-arid regions of northwestern China, the open-pit waste dumps of mining areas suffer from severe water erosion and the limited water-holding capacities of shallow cover soils. This restricts the ecological restoration of abandoned mine lands. Capillary barrier covers can enhance the water-holding capacities of water storage layers due to the differential hydraulic properties at the interface between fine- and coarse-grained layers. However, both the feasibility of constructing layered covers by mixing solid waste slags from waste dumps with clay and the water regulation performance of the covers are yet to be verified in the field. …

An Experimental Study On The Compressive Shear Failure Characteristics Of Mining-Induced Fractured Rock Blocks In The Absence Of Lateral Confinement And Under Unilateral Confinement, Wang Wenxue, Zhang Shicheng, Li Linyang, Zhang Ruochen, Liang Yankun, Chang Jian, Pan Xuwei, Zhao Guizhang

Coal Geology & Exploration

Objective Rock bridges exert a controlling influence on the deformation, fracture field evolution, and structural stability of mining-induced fractured rock masses. Therefore, it is necessary to investigate their deformation and failure characteristics, as well as the underlying controlling mechanisms, under different confinement conditions. Such investigations will provide theoretical support for the safe mining of underground coal seams and the prevention and control of mining-induced disasters. Methods Mechanical models of fractured rock blocks containing rock bridges were established. Specimens with different fracture dip angles, rock bridge widths, and material strengths were prepared using rock-like materials. Furthermore, an independently developed compressive shear …