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Chinese Journal of Mechanical Engineering 2024年第1期37卷 203-214页

作者： Xiaokang Huang Xiaoyong Tian Qi Zhong Shunwen He cunbao huo Yi Cao Zhiqiang Tong Dichen Li State Key Laboratory of Manufacturing Systems Engineering Xi’an Jiaotong UniversityXian 710049China

Improvement of fabrication efficiency and part performance was the main challenge for the large-scale powder bed fusion(PBF)*** this study,a dynamic monitoring and feedback system of powder bed temperature field using an infrared thermal imager has been established and integrated into a four-laser PBF equipment with a working area of 2000 mm×2000 *** heat-affected zone(HAZ)temperature field has been controlled by adjusting the scanning speed ***,the relationship among spot size,HAZ temperature,and part performance has been *** fluctuation of the HAZ temperature in four-laser scanning areas was decreased from 30.85℃to 17.41℃.Thus,the consistency of the sintering performance of the produced large component has been *** on the controllable temperature field,a dynamically adjusting strategy for laser spot size was proposed,by which the fabrication efficiency was improved up to 65.38%.The current research results were of great significance to the further industrial applications of large-scale PBF equipment.

关键词： Powder bed fusion Efficiency Large-scale Spot size Heat-affected zone(HAZ)

Effects of fracture evolution and non-Darcy flow on the thermal performance of enhanced geothermal system in 3D complex fractured rock

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International Journal of Mining Science and Technology 2024年第4期34卷 443-459页

作者： Yachen Xie Jianxing Liao Pengfei Zhao Kaiwen Xia cunbao Li Department of Civil and Mineral Engineering University of TorontoToronto M5S1A4Canada College of Water Resources and Hydropower Sichuan UniversityChengdu 610225China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsWuhan 430071China College of Civil Engineering Guizhou UniversityGuiyang 550025China Institute of Geosafety School of Engineering and TechnologyChina University of GeosciencesBeijing 100083China State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering Shenzhen UniversityShenzhen 518060China

In fractured geothermal reservoirs,the fracture networks and internal fluid flow behaviors can significantly impact the thermal *** this study,we proposed a non-Darcy rough discrete fracture network(NR-DFN)model that can simultaneously consider the fracture evolution and non-Darcy flow dynamics in studying the thermo-hydro-mechanical(THM)coupling processes for heat extraction in geothermal *** further employed the model on the Habanero enhanced geothermal systems(EGS)project located in ***,our findings illustrate a clear spatial-temporal variation in the thermal stress and pressure perturbations,as well as uneven spatial distribution of shear failure in 3D fracture *** shear failure is mainly concentrated in the first fracture ***,channeling flow have also been observed in DFNs during heat extraction and are further intensified by the expansion of fractures driven by thermal ***,the combined effect of non-Darcy flow and fracture evolution triggers a rapid decline in the resulting heat rate and *** NR-DFN model framework and the Habanero EGS's results illustrate the importance of both fracture evolution and non-Darcy flow on the efficiency of EGS production and have the potential to promote the development of more sustainable and efficient EGS operations for stakeholders.

关键词： Coupled THM model Non-Darcy flow Deformable DFN Enhanced geothermal systems

Anisotropic time-dependent behaviors of shale under direct shearing and associated empirical creep models

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1262-1279页

作者： Yachen Xie Michael Z.Hou Hejuan Liu cunbao Li Shenzhen Key Laboratory of Deep Engineering Sciences and Green Energy Shenzhen UniversityShenzhen518060China Institute of Subsurface Energy Systems Clausthal University of TechnologyClausthal-Zellerfeld38678Germany State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China

Understanding the anisotropic creep behaviors of shale under direct shearing is a challenging *** this context,we conducted shear-creep and steady-creep tests on shale with five bedding orientations (i.e.0°,30°,45°,60°,and 90°),under multiple levels of direct shearing for the first *** results show that the anisotropic creep of shale exhibits a significant stress-dependent *** a low shear stress,the creep compliance of shale increases linearly with the logarithm of time at all bedding orientations,and the increase depends on the bedding orientation and creep *** high shear stress conditions,the creep compliance of shale is minimal when the bedding orientation is 0°,and the steady-creep rate of shale increases significantly with increasing bedding orientations of 30°,45°,60°,and 90°.The stress-strain values corresponding to the inception of the accelerated creep stage show an increasing and then decreasing trend with the bedding orientation.A semilogarithmic model that could reflect the stress dependence of the steady-creep rate while considering the hardening and damage process is *** model minimizes the deviation of the calculated steady-state creep rate from the observed value and reveals the behavior of the bedding orientation's influence on the steady-creep *** applicability of the five classical empirical creep models is quantitatively *** shows that the logarithmic model can well explain the experimental creep strain and creep rate,and it can accurately predict long-term shear creep *** on an improved logarithmic model,the variations in creep parameters with shear stress and bedding orientations are *** abovementioned findings,a mathematical method for constructing an anisotropic shear creep model of shale is proposed,which can characterize the nonlinear dependence of the anisotropic shear creep behavior of shale on the bedding orientation.

关键词： Rock anisotropy Direct shear creep Creep compliance Steady-creep rate Empirical model Creep constitutive model

A novel box-counting method for quantitative fractal analysis of threedimensional pore characteristics in sandstone

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International Journal of Mining Science and Technology 2024年第4期34卷 479-489页

作者： Huiqing Liu Heping Xie Fei Wu cunbao Li Renbo Gao State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400030China School of Resources and Safety Engineering Chongqing UniversityChongqing 400030China Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Shenzhen UniversityShenzhen 518060China Shenzhen Key Laboratory of Deep Underground Engineering Sciences and Green Energy College of Civil and Transportation EngineeringShenzhen UniversityShenzhen 518060China

Fractal theory offers a powerful tool for the precise description and quantification of the complex pore structures in reservoir rocks,crucial for understanding the storage and migration characteristics of media within these *** with the challenge of calculating the three-dimensional fractal dimensions of rock porosity,this study proposes an innovative computational process that directly calculates the three-dimensional fractal dimensions from a geometric *** employing a composite denoising approach that integrates Fourier transform(FT)and wavelet transform(WT),coupled with multimodal pore extraction techniques such as threshold segmentation,top-hat transformation,and membrane enhancement,we successfully crafted accurate digital rock *** improved box-counting method was then applied to analyze the voxel data of these digital rocks,accurately calculating the fractal dimensions of the rock pore *** numerical simulations of permeability experiments were conducted to explore the physical correlations between the rock pore fractal dimensions,porosity,and absolute *** results reveal that rocks with higher fractal dimensions exhibit more complex pore connectivity pathways and a wider,more uneven pore distribution,suggesting that the ideal rock samples should possess lower fractal dimensions and higher effective porosity rates to achieve optimal fluid transmission *** methodology and conclusions of this study provide new tools and insights for the quantitative analysis of complex pores in rocks and contribute to the exploration of the fractal transport properties of media within rocks.

关键词： 3D fractal analysis Fractal dimension Rock pore structure Box-counting method Permeability simulation Computational geosciences

3D digital-image correlation insight into generalized relaxation behavior of sandstone under stress and pore pressure coupling

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2516-2536页

作者： Cancan Chen Heping Xie Jiang Xu Seisuke Okubo Shoujian Peng cunbao Li Minghui Li State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering Shenzhen UniversityShenzhen518060China Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Institute of Deep Earth Sciences and GreenEnergyCollege of Civil and Transportation EngineeringShenzhen UniversityShenzhen518060China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China

The occurrence of geological hazards and the instability of geotechnical engineering structures are closely related to the time-dependent behavior of ***,the idealization boundary condition for constant stress in creep or constant strain in relaxation is not usually attained in natural geological ***,generalized relaxation tests that explore the simultaneous changes of stress and strain with time under different stress levels with constant pore-water pressure are conducted in this *** results show that in area I,area II,and area III,the stress and strain both change synchronously with time and show similar evolutionary laws as the strain-time curve for creep or the stress-time curve for *** the applied stress level surpasses the sci or scd threshold,the variations in stress and strain and their respective rates of change exhibit a significant *** radial deformation and its rate of change exhibit greater sensitivity in response to stress *** apparent strain deforms homogeneously at the primary stage,and subsequently,gradually localizes due to the microcrack development at the secondary ***,interconnection of the microcracks causes the formation of a shear-localization zone at the tertiary *** strain-time responses inside and outside the localization zone are characterized by local strain accumulation and inelastic unloading during the secondary and tertiary stages,*** width of the shear-localization zone is found to range from 4.43 mm to 7.08 mm and increased with a longer *** electron microscopy(SEM)reveals a dominant coalescence of intergranular cracks on the fracture surface,and the degree of physiochemical deterioration caused by water-rock interaction is more severe under a longer *** brittle sandstone’s time-dependent deformation is essentially controlled by microcrack development during generalized relaxation,and its expectancy-life is determi

关键词： Generalized relaxation Stress level Direction coefficient Major-strain field Microcrack damage Stress threshold

Hydraulic fracturing behaviors of shale under coupled stress and temperature conditions simulating different burial depths

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International Journal of Mining Science and Technology 2024年第6期34卷 783-797页

作者： Qin Zhou Zheming Zhu Wei Liu Huijun Lu Zidong Fan Xiaofang Nie cunbao Li Jun Wang Li Ren MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Downhole Operating Company CNPC Chuanqing Drilling and Exploration Engineering Co.Ltd.Shenzhen 518060China School of Architecture and Civil Engineering Xihua UniversityChengdu 610065China Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Shenzhen UniversityShenzhen 518060China

Fracture propagation in shale under in situ conditions is a critical but poorly understood mechanical process in hydraulic fracturing for deep shale gas *** address this,hydraulic fracturing experiments were conducted on hollow double-wing crack specimens of the Longmaxi shale under conditions simulating the ground surface(confining pressure rcp=0,room temperature(Tr))and at depths of 1600 m(rcp=40 MPa,Ti=70C)and 3300 m(rcp=80 MPa,high temperature Ti=110C)in the study *** in situ stress was found to significantly increase fracture toughness through constrained microcracking and particle frictional bridging *** the temperature enhances rather than weakens the fracture resistance because it increases the grain debonding length,which dissipates more plastic energy and enlarges grains to close microdefects and generate compressive stress to inhibit ***,the fracture toughness anisotropy in the shale was found to be nearly constant across burial depths,despite reported variations with increasing confining *** water was not found to be as important as the in situ environment in influencing shale *** findings emphasize the need to test the fracture toughness of deep shales under coupled in situ stress and temperature conditions rather than focusing on either in situ stress or temperature alone.

关键词： Hydraulic fracturing Fracture toughness Shale Anisotropy Deep rock mechanics

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铜基载氧体催化电厂烟气脱氧研究

燃料化学学报（中英文） 2024年第6期52卷 839-849页

作者：司马皓王雪峰邓存宝太原理工大学安全与应急管理工程学院山西太原030024

电厂烟气主要成分为N_(2)、CO_(2)和部分O_(2),将电厂烟气注入矿井采空区可实现CO_(2)封存,并替代注氮气防治遗煤自燃,但是烟气中的O_(2)是造成遗煤自燃的因素之一。因此,亟待开发一种经济有效的催化剂来脱除电厂烟气中的O_(2)。本研究... 详细信息

电厂烟气主要成分为N_(2)、CO_(2)和部分O_(2),将电厂烟气注入矿井采空区可实现CO_(2)封存,并替代注氮气防治遗煤自燃,但是烟气中的O_(2)是造成遗煤自燃的因素之一。因此,亟待开发一种经济有效的催化剂来脱除电厂烟气中的O_(2)。本研究采用共沉淀法,通过调变载体和负载量可控制备了铜基催化剂和系列xCuO/CeO_(2)催化剂,利用BET、XRD、ICP、TEM、H_(2)-TPR和XPS等手段对催化剂进行了表征,并建立催化剂结构与催化电厂烟气脱氧性能之间的构效关系。结果表明,CeO_(2)的加入提高了CuO的分散性、增加了催化剂的氧空位,提高了催化剂的活性和还原氧化性能,Cu-Ce界面结构的协同效应促进了还原氧化过程,表现出良好的活性和循环稳定性。30CuO/CeO_(2)由于其CuO颗粒尺寸最小、分散性最高、氧空位浓度最高,表现出较优的催化电厂烟气脱氧性能。本研究为开发低成本可循环使用、高活性和高稳定性的脱氧催化剂提供了参考。

关键词：化学链燃烧 CuO/CeO_(2) 氧化还原界面结构氧空位

直接剪切下页岩的各向异性破坏特征和强度预测模型

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工程科学与技术 2024年第2期56卷 257-267页

作者：叶春烽谢和平李存宝深圳大学深地工程智能建造与健康运维全国重点实验室广东深圳518060 重庆大学煤矿灾害动力学与控制全国重点实验室重庆400044

了解页岩剪切破坏特性对页岩气储层改造和井壁稳定性控制具有重要意义。然而,由于页岩本身的各向异性属性,页岩的剪切破坏行为复杂。本文对6种不同层理倾角(0°、30°、60°、90°、120°和150°)的立方体页岩进行了系统的直接剪切破坏... 详细信息

了解页岩剪切破坏特性对页岩气储层改造和井壁稳定性控制具有重要意义。然而,由于页岩本身的各向异性属性,页岩的剪切破坏行为复杂。本文对6种不同层理倾角(0°、30°、60°、90°、120°和150°)的立方体页岩进行了系统的直接剪切破坏测试,详细分析了在层理弱面影响下页岩的剪切应力–剪切位移、抗剪强度、剪切模量和破坏模式的各向异性特征。结果表明:页岩的剪切破坏表现为典型的非线性渐进破坏特征;页岩平均抗剪强度和剪切模量随层理倾角的增加均呈现“M”型变化趋势;在90°~180°的层理倾角区间,平均抗剪强度的极值差明显大于0°~90°区间,而剪切模量近似关于90°呈对称变化;当层理倾角从0°变化到180°时,页岩剪切各向异性行为呈现非对称演化规律。在层理倾角和直接剪切荷载作用下,页岩的破坏模式有3类:层理倾角为0°时,沿层理面剪切滑移破坏;层理倾角为30°、60°和90°时,表现为穿透层理和基质的剪切滑移破坏;其他倾角下呈现穿透层理和基质的剪切滑移与沿层理的拉伸劈裂相结合的复合破坏。基于试验结果和组构张量,构建了一个可考虑页岩本征各向异性和剪应力诱导各向异性影响的直接剪切破坏准则,其理论预测值与试验结果的平均偏差率低于3%,能够定量表征黏聚力和摩擦系数的各向异性程度,合理评估页岩直接剪切强度对外加法向应力的敏感性,可推广应用于理论表征所有层状岩土材料的直接剪切强度。

关键词：各向异性直接剪切抗剪强度非对称破坏模式剪切破坏准则

经验知识监督的RC墩柱力学性能神经网络分析方法

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工程科学与技术 2024年第1期56卷 35-43页

作者：刘振亮李素超赵存宝石家庄铁道大学安全工程与应急管理学院河北石家庄050043 河北省大型结构健康诊断与控制重点实验室河北石家庄050043 哈尔滨工业大学(威海)土木工程系山东威海264209

基于试验或数值模拟的单一墩柱力学性能分析方法难以兼顾计算精度和效率,纯数据驱动的分析方法存在可解释性差和对数据依赖性强等问题。为此,本文通过研究钢筋混凝土(RC)墩柱力学性能试验数据、经验知识和机器学习的融合机制,提出了经... 详细信息

基于试验或数值模拟的单一墩柱力学性能分析方法难以兼顾计算精度和效率,纯数据驱动的分析方法存在可解释性差和对数据依赖性强等问题。为此,本文通过研究钢筋混凝土(RC)墩柱力学性能试验数据、经验知识和机器学习的融合机制,提出了经验知识监督的RC墩柱力学性能神经网络(knowledge-guided neural network,KGNN)分析方法。首先,建立了包含761组RC墩柱拟静力试验样本的数据库;随后,基于经验知识分析了RC墩柱主要特征对其力学性能的影响规律,构建了相应的数学表征方法;最后,将RC墩柱试验数据及经验知识融入人工神经网络架构和训练过程,建立了高精度、可解释、可通用且不依赖大量训练数据的RC墩柱力学性能KGNN分析模型。本文提出的KGNN分析方法与纯数据驱动神经网络(BPNN)的结果对比表明:BPNN在测试集上表现更好,在分析墩柱承载力时均方根误差(E)和拟合系数(R^(2))分别为0.070和0.978,KGNN模型的E和R^(2)分别为0.108和0.942;但由于BPNN所预测的墩柱特征对承载力的影响规律与经验知识并不吻合,即未能准确反映墩柱特征与其力学性能间的关系,BPNN模型发生了过拟合;而KGNN方法不仅可以快速准确获得RC墩柱力学性能,且预测规律与经验知识吻合较好,具有更高的可靠性和实用性。因此,融合试验数据与经验知识的神经网络有望成为一种新的RC结构力学性能分析方法。

关键词：钢筋混凝土墩柱数物融合的神经网络经验知识力学性能试验数据库

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焦煤氧化燃烧特性参数与热动力学特征

西安科技大学学报 2024年第4期44卷 709-719页

作者：王成博雷昌奎邓存宝太原理工大学安全与应急管理工程学院山西太原030024 陕西山利科技发展有限责任公司陕西西安710075

煤氧化自燃是矿井火灾的主要原因之一。为了探明煤氧化燃烧的特点和规律,采用TG-DTG试验研究了沙曲一号煤矿焦煤氧化热解过程,对不同升温速率下煤样的特征温度和燃烧特性参数进行了计算,并根据改进的Starink法计算了缓慢失重阶段和燃烧... 详细信息

煤氧化自燃是矿井火灾的主要原因之一。为了探明煤氧化燃烧的特点和规律,采用TG-DTG试验研究了沙曲一号煤矿焦煤氧化热解过程,对不同升温速率下煤样的特征温度和燃烧特性参数进行了计算,并根据改进的Starink法计算了缓慢失重阶段和燃烧失重阶段的热动力学参数,确定了这2个阶段的动力补偿效应。结果表明:特征温度点随升温速率的增大出现了后移现象,并且反应结束后的残余物质比例随着升温速率的增大而增加;燃烧特性参数随升温速率增大呈现显著增大趋势,升温速率越大,煤粉可燃性越好,燃烧越稳定,但反应也越不充分;表观活化能在缓慢失重阶段呈现逐渐增大的趋势,最大值188.47 kJ/mol在着火点T_(3)附近;在燃烧失重阶段当转化率小于0.3时,表观活化能逐渐增大,之后逐渐减小,最大值173.65 kJ/mol在最大失重速率温度点T_(4)附近;指前因子整体变化规律与表观活化能基本一致,动力学补偿效应在燃烧失重阶段更大。

关键词：煤自燃升温速率燃烧特性参数热动力学参数最概然机理函数动力补偿效应