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Thermal effects on prediction accuracy of dense granite mechanical behaviors using modified maximum tangential stress criterion

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1734-1748页

作者： Gan Feng Chun Zhu Xiaochuan Wang shibin tang College of Water Resource and Hydropower Sichuan UniversityChengdu610065China Key Laboratory of Deep Earth Science and Engineering(Sichuan University) Ministry of EducationChengdu610065China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan UniversityWuhan430072China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian116024China

Thermally-induced changes in the fracture properties of geological reservoir rocks can influence their stability,transport characteristics,and performance related to various deep subsurface energy projects.The modified maximum tangential stress(MMTS)criterion is a classical theory for predicting the fracture instability of rocks.However,there is a lack of research on the accuracy of MMTS theory when rocks are subjected to different temperatures.In this study,mechanical theoretical analysis and failure and fracture mechanics experiments of granite under the influence of temperatures ranging from 20℃to 600℃are carried out.The results showed that the theoretical estimated value of MMTS differs significantly from the experimental data at 20℃-600℃.The Keff/KIC ratio is less than the experimental test value due to the critical crack growth radius(rc)estimated by the conventional method being larger than the critical crack growth radius(rce)derived from the experimental data.Varied temperatures affect the fracture process zone size of fine-grained,compact granite,and the MMTS theoretical estimation results.Therefore,it is essential to modify the critical crack growth radius for MMTS theory to accurately predict the fracture characteristics of thermally damaged rocks.In addition,the variation of the rock’s me-chanical properties with temperature and its causes are obtained.Between 20℃and 600℃,the mode-Ⅰ,mode-Ⅱ,and mixed-mode(a-30℃and 45℃)fracture toughness and Brazilian splitting strength of the granite decrease by 80%and 73%,respectively.When the rock is heated above 400℃,its deterioration is mainly caused by a widening of its original cracks.

关键词： Underground geotechnical engineering Hot dry rock(HDR) Geothermal temperature Fracture behavior

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特厚煤层底板断层破坏与顶板垮断联动效应的CFDEM模拟研究

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煤炭学报 2024年第6期49卷 2615-2629页

作者：李浩唐世斌康志勤杨栋马立强太原理工大学原位改性采矿教育部重点实验室山西太原030000 大连理工大学土木工程学院岩石破裂与失稳研究所辽宁大连116024 中国矿业大学矿业工程学院江苏徐州211116

特厚煤层采场空间大、覆岩扰动范围广,顶板垮断产生的强扰动加卸荷载易导致底板断层破坏加剧。通过数值模拟研究特厚煤层底板断层突水与顶板垮断联动效应机理规律是开展水害防治的基础,关键在于掌握加卸载下岩体渐进破坏与裂隙流耦合特... 详细信息

特厚煤层采场空间大、覆岩扰动范围广,顶板垮断产生的强扰动加卸荷载易导致底板断层破坏加剧。通过数值模拟研究特厚煤层底板断层突水与顶板垮断联动效应机理规律是开展水害防治的基础,关键在于掌握加卸载下岩体渐进破坏与裂隙流耦合特征。构建加卸载下拉、剪损伤演化方程,结合有效偏/球应力为基本变量的屈服准则与塑性势函数,得到完整岩块的塑性损伤本构;建立拉/剪、混合型加卸载过程中塑性位移与强度劣化关系,以平方拉剪应力与B-K准则为初始、完全断裂准则,形成非贯通裂隙断裂本构;提出岩块分离、压缩、剪切判据,结合实验数据建立离散块体间挤压、剪切摩擦本构与剪胀方程。基于质量/动量守恒、状态方程,并结合流体体积与浸没边界方法,形成裂隙岩体气−水二相流模拟理论。由此形成CFDEM数值计算程序,并将加卸载下塑性损伤、断裂、挤压/摩擦、流体属性分别赋予实体单元(岩块)、黏聚力单元(非贯通裂隙)、接触对(贯通裂隙)、欧拉单元(水和气)。根据宁武煤田北部矿区工程地质条件,建立特厚煤层底板断层突水与顶板垮断联动效应数值计算模型。结果表明:①CFDEM耦合程序及相应的理论模型可数值实现特厚煤层覆岩及底板断层从(准)连续体到离散体转化,以及地下水在裂隙中运移;②模拟条件下特厚煤层含断层底板的采动裂隙包络线呈w形,最深处超过55 m位于断层及其上盘,最浅处23 m位于断层下盘,而无构造底板处的破坏深度为24~36 m,已导通奥灰含水层;③特厚煤层底板普遍出现二次破坏现象。表现为无构造底板在超前工作面处破坏深度为24.0~29.3 m,但在采空区内普遍增加至31.5~36.0 m;断层及其上盘在超前工作面处裂隙总开度为0.34~0.86 m,但在采空区内迅速增加至3.6 m,形成突水优势通道。④底板断层突水与顶板垮断联动效应的根源在于覆岩高位关键岩层垮断失稳、砌体梁下沉与二次断裂,并导致底板二次破坏,突水风险加剧。

关键词：特厚煤层底板断层突水顶底板联动效应 CFDEM程序微震实验

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南宁市江南公园儿童游乐区植物景观调查与分析

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广西林业科学 2024年第1期53卷 80-86页

作者：苏丽达唐世斌广西大学林学院广西南宁530004

植物是城市公园绿地的必要组成元素,也是儿童进行户外自然体验的重要载体。为了解南宁市江南公园儿童游乐区植物资源和景观空间现状,采用实地踏查法,对其植物景观进行调查与分析。结果表明,江南公园儿童游乐区内共有园林植物59种,隶属... 详细信息

植物是城市公园绿地的必要组成元素,也是儿童进行户外自然体验的重要载体。为了解南宁市江南公园儿童游乐区植物资源和景观空间现状,采用实地踏查法,对其植物景观进行调查与分析。结果表明,江南公园儿童游乐区内共有园林植物59种,隶属于34科54属;植物生活型较齐全,以常绿乔木和灌木为主,共占植物总种数的64.41%;植物观赏特性以观叶、观花为主,观叶和观花植物分别占植物总种数的59.32%和57.63%;乡土植物36种,外来植物23种,分别占植物总种数的61.02%和38.98%;植物空间形式包括开敞式、半开敞式和覆盖式3类,植物空间丰富,但植物种类和配置形式的趣味性偏低。从儿童视角出发,通过探索植物趣味性功能、提升植物物种丰富度及挖掘植物知识和文化内涵等方式,打造可供儿童游乐、体验和学习的城市公园活动空间。

关键词：植物资源植物空间儿童游乐区

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不同围压与水压下红砂岩三轴剪切–渗流试验研究

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岩石力学与工程学报 2024年第4期43卷 862-877页

作者：赵成业梁正召张培森唐世斌陈凡宋文成大连理工大学海岸和近海工程国家重点实验室辽宁大连116024 大连理工大学岩石破裂与失稳研究中心辽宁大连116024 山东科技大学矿山灾害预防控制国家重点实验室培育基地山东青岛266590 山东科技大学矿业工程国家级实验教学示范中心山东青岛266590

为研究红砂岩剪切开裂过程中及剪切破坏前后力学与渗流规律,基于Rock Top多场耦合试验仪及自制剪切导流组件,实现三轴应力环境下的标准圆柱形试件剪切试验条件,开展不同围压、渗透压差作用下红砂岩三轴剪切–渗流试验研究,并利用离散元... 详细信息

为研究红砂岩剪切开裂过程中及剪切破坏前后力学与渗流规律,基于Rock Top多场耦合试验仪及自制剪切导流组件,实现三轴应力环境下的标准圆柱形试件剪切试验条件,开展不同围压、渗透压差作用下红砂岩三轴剪切–渗流试验研究,并利用离散元颗粒方法研究不同尺寸、形状模型的剪切开裂过程。研究表明:(1)峰前剪应力随剪切变形整体呈线性上升趋势,峰后剪切及环向变形速率加快,剪应力出现1~3次应力降;围压越大,峰前变形曲线斜率越大,剪切变形终值递增,环向变形–剪切位移曲线则越趋于平缓;峰值环向变形较为集中。(2)剪切–渗流过程可分为渗流中断阶段、渗流状态转变阶段、渗流速度逐增阶段,剪应力特征值与围压具有良好的线性关系。(3)岩样表现为宏观单一剪切面破坏,围压越大,断口边缘破碎越严重,端部剪切裂缝越大。(4)剪切破坏前后渗流量与围压服从幂函数递减规律;渗流量均随渗透压差升高而呈现极好的线性关系,且流量–渗透压差拟合曲线斜率随着围压的增大而减小;剪应力卸荷后的渗流量相比于卸荷前降低一个数量级,且随着围压增大,两者之间的差值逐渐减小。(5)模拟结果与试验相似,显示围压约束和法向约束条件下均出现斜向剪切裂纹,斜剪裂纹发育角度及密度受长径比、体积影响,三维尺寸比例为1时其影响程度最小,等尺寸比时三轴剪切强度弱于直剪强度。以上研究结果表明此次三轴剪切试验无论在方法、结果方面均具有一定的可靠性。

关键词：岩石力学剪切–渗流围压渗透压差剪切破坏

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Boundary-effect and scale-heating rate equivalence effect of cracking behavior in the rock models subjected to heating from the central borehole

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Science China(Technological Sciences) 2020年第5期63卷 809-818页

作者： HUANG Xin tang shibin tang ChunAn State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

Thermal cracking is broadly observed in rock engineering.A finite element numerical model which considers the heterogeneity of rock materials and the damage evolution process was used to simulate the thermal cracking behavior of square rock samples heated from the central borehole.The thermal and mechanical behaviors of two cases,i.e.,the case with large size but low heating rate and the case with small size but high heating rate were compared to study the crack initiation location in the models with different model sizes and heating rates.The simulated stress and temperature fields,as well as the failure pattern,were in good agreement with the experimental observations.The temperature and thermal stress distribution during the heating process in both cases indicated that high tensile stress was concentrated around the thermal gradient front,which resulted in the cracks initiating at the location with a certain distance away from the borehole.The results show that under the same heating rate,crack initiation location moves outwards with the increment of the model size then remains approximately at one location,which reflects the boundary-effect.Furthermore,the results indicate that the relative crack initiation locations in two cases are nearly the same if the ratio between the heating rate in two cases(Tx/Ty)nearly equal to the square of the inverse ratio of corresponding model side lengths((ay/ax)2).This concept is named the scale-heating rate equivalence effect in this study.It is beneficial for studying thermal cracking of rock both numerically and experimentally since the model size can be significantly decreased.

关键词： thermal cracking nuclear waste disposal numerical simulation boundary-effect scale-heating rate equivalence effect

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Discontinuous deformation and displacement analysis: From continuous to discontinuous

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Science China(Technological Sciences) 2015年第9期58卷 1567-1574页

作者： tang ChunAn tang shibin GONG Bin BAI HongMei State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian Mechsoft Co. Ltd.

A discontinuous deformation and displacement(DDD) analysis method is proposed for modelling the rock failure process. This method combines the rock failure process analysis(RFPA) method(based on finite element method) and discontinuous deformation analysis(DDA) method. RFPA is used to simulate crack initiation, propagation and coalescence processes of rock during the small deformation state. The DDA method is used to simulate the movement of blocks created by the multiple cracks modelled by the RFPA. The newly developed DDD method is particularly suitable for modelling both crack propagation and block movement during the rock failure process because of the natural and convenient coupling of continuous and discontinuous deformation analyses. The proposed method has been used to simulate crack initiation, propagation and coalescence within a slope as well as the block movement during the landslide process. Numerical modelling results indicate that the proposed DDD method can automatically simulate crack propagation and block movement during the rock failure process without degrading accuracy.

关键词：位移分析不连续变形非连续变形分析岩石破裂过程数值模拟 DDA方法块体运动 RFPA

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Determination of T-stress using finite element analysis

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Science China(Technological Sciences) 2017年第8期60卷 1211-1220页

作者： tang shibin DONG Zuo HUANG RunQiu State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology

A method that uses finite element analysis to determine the non-singular stress(T-stress) at a crack tip is proposed in this study.T-stress includes two components:the T_x-stress parallel to the tangent of the crack at its tip and the 7Vstress perpendicular to this tangent.The effects of contact and friction on both the T_x-and T_y-stresses on the crack flanks are considered in the method.Because the method uses a single standard elastic finite element analysis derived directly from the equation of the stress fields around the crack tip and does not require any assumptions or simplification,it can be used to determine the T-stress for any given geometry and loading condition.Theoretical results are used to calibrate the results,which exhibited good agreement and to discuss the T-stress computational methodology.Furthermore,the T_x-and T_y-stresses in center-cracked Brazilian disc(CCBD) specimens subjected to diametrical or partially distributed compression were numerically computed,and the effects of contact and friction on the T_x-and T_y-stresses are discussed.

关键词：有限元分析应力测定裂纹尖端应力计算方法组成部分载荷条件数值计算巴西圆盘

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Applications of rock failure process analysis (RFPA) method

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Journal of Rock Mechanics and Geotechnical Engineering 2011年第4期3卷 352-372页

作者： Chun＇an tang shibin tang lnstitute for Rock Instability and Seismicity Research Dalian University of Technology Dalian 116024 China

Brittle failure of rocks is a classical rock mechanical problem. Rock failure not only involves initiation and propagation of single crack, but also is associated with initiation, propagation and coalescence of many cracks. The rock failure process analysis （RFPA） tool has been proposed since 1995. The heterogeneity of rocks at a mesoscopic level is considered by assuming that the material properties follow the Weibull distribution. Elastic damage mechanics is used for describing the constitutive law of the meso-level element. The finite element method （FEM） is employed as the basic stress analysis tool. The maximum tensile strain criterion and the Mohr-Coulomb criterion are utilized as the damage threshold. In order to solve the stability problem related to rock engineering structures, fundamental principles of strength reduction method （SRM） and gravity increase method （GIM） are integrated into the RFPA. And the acoustic emission （AE） event rate is employed as the criterion for rock engineering failure. The prominent feature of the RFPA-SRM and RFPA-GIM for stability analysis of rock engineering is that the factor of safety can be obtained without any presumption for the shape and location of the failure surface. In this paper, several geotechnical engineering applications that use the RFPA method to analyze their stability are presented to provide some references for relevant researches. The principles of the RFPA method in engineering are introduced firstly, and then the stability analysis of tunnel, slope and dam is focused on. The results indicate that the RFPA method is capable of capturing the mechanism of rock engineering stability and has the potential for application in a larger range of geo-engineering.

关键词： case studies rock slopes and fotmdations stability analysis rock failure

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岩石材料裂纹尖端起裂特性研究

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岩石力学与工程学报 2017年第3期36卷 552-561页

作者：唐世斌张恒大连理工大学岩石破裂与失稳研究所辽宁大连116024

通过综合考虑Williams展开式中奇异应力项和非奇异应力项(T应力),运用断裂力学方法深入探讨远场拉–压、压–压应力组合下裂纹尖端起裂特性。在最大周向应力准则中考虑T应力的影响作用,并将其作为拉伸破裂判据;在剪切破裂方面,提出考虑... 详细信息

通过综合考虑Williams展开式中奇异应力项和非奇异应力项(T应力),运用断裂力学方法深入探讨远场拉–压、压–压应力组合下裂纹尖端起裂特性。在最大周向应力准则中考虑T应力的影响作用,并将其作为拉伸破裂判据;在剪切破裂方面,提出考虑法向应力影响的最大剪应力准则。通过对拉伸和剪切破裂发生条件的探讨,进一步阐明剪切破坏与裂纹倾角、内摩擦角、抗拉强度、黏聚力等参数之间的关系。研究结果表明,Williams展开式中非奇异应力项对于裂纹起裂角有重要的影响,所提出理论比传统理论计算的起裂角与实验结果更加吻合。随着内摩擦角的增大,剪切破裂减弱而拉伸破裂增强。随着黏聚力增大或者抗拉强度降低,拉伸破裂增强而剪切破裂减弱。

关键词：岩石力学起裂角裂纹扩展剪切破坏断裂判据

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低温诱发岩石破裂的理论与数值模拟研究

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岩石力学与工程学报 2018年第7期37卷 1596-1607页

作者：唐世斌罗江唐春安大连理工大学土木工程学院辽宁大连116024 大连理工大学岩石破裂与失稳研究所辽宁大连116024

低温诱发岩石开裂在油气开发、地热开采、液化石油气储存等方面都有所涉及,低温液体引起的岩石破裂值得关注。针对这一问题,首先运用热弹性理论获得平板模型单面遭受冷冲击时,其内部温度和应力演化的理论解。运用理论公式研究温度的传... 详细信息

低温诱发岩石开裂在油气开发、地热开采、液化石油气储存等方面都有所涉及,低温液体引起的岩石破裂值得关注。针对这一问题,首先运用热弹性理论获得平板模型单面遭受冷冲击时,其内部温度和应力演化的理论解。运用理论公式研究温度的传导规律和应力的演化特征,并分析换热系数对降温速率和拉应力增加速率的影响作用。结果表明,平板模型表面遭受冷冲击时,冲击边沿处温度先急剧降低,然后逐渐减缓,并最终达到与环境相同的温度;拉应力也先急剧升高而后逐渐降低,并最终降低至0。此外,为了重现冷冲击作用下岩石的破裂过程,揭示冷冲击参数对岩石低温下的破裂机制和特征,运用数值模拟方法研究岩石承受降温冲击作用下的裂纹扩展过程,分析换热系数对岩石温度和最小主应力分布的影响作用,并对不同换热系数条件下岩石产生的裂纹数量进行定量分析。数值模拟结果表明,增大换热系数不仅提高了换热边界的拉应力,使岩石更易于开裂,同时也增加了产生的裂纹数量和扩大了裂纹区的范围,有利于提高低渗透油气藏的渗透性。

关键词：岩石力学低温开裂岩石破裂数值模拟裂纹扩展

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