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Core discing characteristics and mitigation approach by a novel developed drill bit in deep rocks

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Journal of Central South University 2020年第10期27卷 2822-2833页

作者： zheng Min-zong LI Shao-jun YAO Zou ZHANG Ao-dong XU Ding-ping zhou Ji-fang state key Laboratory of {2. and geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China Faculty of engineering China University of GeosciencesWuhan 430074China Yalong River Hydropower Development Co. Ltd.Chengdu 610051China

Core discing often occurs in deep rocks under high-stress conditions and has been identified as an important characteristic for deep rock *** paper presents the formation mechanism of core discing ***,the interaction between diamond drill bits and rock was analyzed based on numerical modeling.A novel drill bit with an inner conical crown for the mitigation of core discing was designed and verified by simulation *** mitigation method was applied in the cavern B1 of CJPL-Ⅱand satisfactory results had been *** percentage of core discing had been obviously decreased from 67.8%when drilling with a rectangular crown drill bit,to 2..5%when an inner conical crown drill bit had been *** paper gives full insight into core discing characteristics and provides a new method for core discing mitigation;it will potentially contribute to stress measurement in deep rock engineering.

关键词： core discing mitigation drill bit crown deep rocks in-situ stress measurements

Thermal effects on fracture toughness of cracked straight-through Brazilian disk green sandstone and granite

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Journal of Rock Mechanics and geotechnical engineering 2022年第5期14卷 1447-1460页

作者： Lei zhou Weiting Gao Liyuan Yu Zheming Zhu Jianxing Chen Xingkai Wang key Laboratory of Deep Earth Science and engineering Ministry of EducationSichuan UniversityChengdu610065China state key Laboratory for {2. and Deep Underground engineering China University of Mining and TechnologyXuzhou221116China Failure Mechanics and engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu610065China key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province Shaoxing UniversityShaoxing312000China

Cracked straight-through Brazilian disc(CSTBD) samples prepared using two rock materials were used for thermal treatment from room temperature to 700℃. Uniaxial splitting experiments were performed using an automatic electro-hydraulic servo press to study the evolution laws of physical and fracture properties of different deep rock materials under high-temperature geological conditions. The fracture characteristics were measured using an industrial camera and digital image correlation technology to analyze the effect of high temperature on fracture properties and failure modes of the CSTBD samples after different thermal treatments. The micro-damage properties of green sandstone and granite materials were obtained using a scanning electron microscope(SEM). The following conclusions were drawn from the test results:(1) With the increasing temperature, the fracture characteristics of green sandstone and granite change from brittle fracture to plasticity fracture, the longitudinal wave velocity of granite decreases sharply at 600℃, and the damage factor reaches 0.8748 at 700℃.(2. The fracture toughness of green sandstone and granite decreases with increasing temperature;however, the decreasing range of granite is larger than that of green sandstone.(3) As the temperature increases, the fracture morphologies of green sandstone and granite materials become rougher, whereas thermal damage cracks of granite and intergranular fractures inside sandstone as well as pores of sandstone increase.(4) The crack tip opening displacement and peak strain corresponding to peak load increase with the temperature.

关键词： High temperature Cracked straight-through Brazilian disc(CSTBD)sample Fracture toughnessm Scanning electron microscope(SEM)

Fabric changes induced by super-absorbent polymer on cementelime stabilized excavated clayey soil

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Journal of Rock Mechanics and geotechnical engineering 2021年第5期13卷 1124-1135页

作者： Xia Bian Lingling Zeng Xiaozhao Li Xiusong Shi Shuming zhou Fuqing Li key Laboratory of Ministry of Education for geomechanics and Embankment {2. Hohai UniversityNanjing210098China College of Civil engineering and Architecture Zhejiang University of TechnologyHanzhou310014China state key Laboratory for {2. and Deep Underground engineering School of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou221116China Beijing Urban Construction Design and Development Group Co. Ltd.Beijing100037China Seazen Holdings Co. Ltd.Shanghai200062China

This paper studies the microstructure variation induced by super-absorbent polymer(SAP)to understand the mechanism of macroscopic strength improvement of stabilized *** fabric changes of cement elime stabilized soil were analyzed with respect to the variation of SAP content,water content,lime content and curing time,using mercury intrusion porosimetry(MIP)*** can be observed that the delimitation pore diameter between inter-and intra-aggregate pores was 0.2.mm for the studied soil,determined through the intrusion/extrusion *** results showed that fabric in both inter-and intra-aggregate pores varied significantly with SAP content,lime content,water content and curing *** main changes in fabric due to SAP are identified as:(1)an increase in intra-aggregate pores(2.mm)due to the closer soilecementelime cluster space at higher SAP content;and(2.a decrease in inter-aggregate pores represented by a reduction in small-pores(0.2.2.mm)due to the lower pore volume of soil mixture after water absorption by SAP,and a slight increase in large-pores(>2.mm)due to the shrinkage of SAP particle during the freezeedry process of MIP ***,the strength gain due to SAP for cementelime stabilized soil was mainly due to a denser fabric with less interaggregate *** cementitious products gradually developed over time,leading to an increase in intra-aggregate pores with an increasing proportion of micro-pores(0.006e0.2.mm).Meanwhile,the inter-aggregate pores were filled by cementitious products,resulting in a decrease in total void ***,the strength development over time is attributable to the enhancement of cementation bonding and the refinement of fabric due to the increasing cementitious compounds.

关键词： Fabric Soil stabilization Microstructure Super-absorbent polymer(SAP)

二氧化碳捕集、利用与封存环境风险问卷调查研究

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环境工程 2018年第2期36卷 6-9,26页

作者：曹丽斌赵学涛蔡博峰谷莹莹周颖李琦马劲风胡丽莎王永胜赵兴雷王保登环境保护部环境规划院气候变化与环境政策研究中心北京100012 北京交通大学北京100044 中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室武汉430070 西北大学地质学系二氧化碳捕集与封存技术国家地方联合工程研究中心西安710069 中国地质调查局水文地质环境地质调查中心河北保定071051 神华鄂尔多斯煤制油分公司内蒙古鄂尔多斯017209 北京低碳清洁能源研究所工艺工程研发中心北京102209

基于对从事应对气候变化的政府管理人员、科研人员和相关企业人员开展问卷调查,分析他们对CCUS技术和相关项目的环境安全性认知程度,为完善《二氧化碳捕集、利用与封存环境风险评估技术指南(试行)》(以下简称《指南》)提供重要依据。结... 详细信息

基于对从事应对气候变化的政府管理人员、科研人员和相关企业人员开展问卷调查,分析他们对CCUS技术和相关项目的环境安全性认知程度,为完善《二氧化碳捕集、利用与封存环境风险评估技术指南(试行)》(以下简称《指南》)提供重要依据。结果显示,大部分被调查对象对CCUS技术有所了解,但是对于CCUS项目的环境安全性认识还比较模糊,未来《指南》的评估范围应侧重于采用最大可信事故计算CO_2.大气、地表水、地下水等扩散来定义或者根据CO_2.移分布来定量评估。CCUS技术各环节对环境风险影响大小进行排序,捕集环节应该重点考虑捕集工艺和环境风险物质,运输环节重点考虑运输设备材质、运输方式和运输规模,利用和封存环节建议4项因素均需充分考虑。

关键词：二氧化碳利用与封存关注度环境风险技术指南

Deformation and failure characteristics and fracture evolution of cryptocrystalline basalt

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Journal of Rock Mechanics and geotechnical engineering 2019年第5期11卷 990-1003页

作者： Zhenjiang Liu Chuanqing Zhang Chunsheng Zhang Yang Gao Hui zhou Zhaorong Chang state key Laboratory of {2. and geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China Powerchina Huadong engineering Corporation Limited Hangzhou310014China School of Architecture and Civil engineering Shenyang University of TechnologyShenyang110870China

Cryptocrystalline basalt is one of the two major types of rocks exposed in the super large-scale underground powerhouse in Baihetan hydropower station in *** rock of this type shows various sitespecific mechanical responses(***,fracturing,and relaxation)during *** conventional triaxial testing facility MTS 815.03,we obtained the stressestrain curves,macroscopic failure characteristics,and strength characteristics of cryptocrystalline *** this basis,evolution of crack initiation and propagation was explored using the finite-discrete element method(FDEM)to understand the failure mechanism of cryptocrystalline *** test results showed that:(1)under different confining stresses,almost all the pre-peak stressestrain curves of cryptocrystalline basalt were linear and the post-peak stresses decreased rapidly;(2.the cryptocrystalline basalt showed a failure mode in a form of fragmentation under low and medium confining stresses while fragmentation-shear coupling failure dominated at high confining stresses;and(3)the initial strength ratio(sci/sf,where sci and sf are the crack initiation strength and peak strength,respectively)ranged from 0.45 to 0.55 and the damage strength ratio(scd/sf,where scd is the crack damage strength)exceeded *** stressestrain curve characteristics and failure modes of cryptocrystalline basalt could be reflected *** this,FDEM simulation was employed to reveal the characteristics of cryptocrystalline basalt,including high scd/sf values and rapid failure after scd,with respect to the microscopic characteristics of mineral *** results showed that the fragmentation characteristics of cryptocrystalline basalt were closely related to the development of tensile cracks in rock samples prior to ***,the decrease in degree of fragmentation with increasing confining stress was also correlated with the dominant effect of confining stress on the tensile cracks.

关键词： Baihetan hydropower station Cryptocrystalline basalt Deformation and failure characteristics Characteristic strengths Crack propagation evolution

湿化膨胀与掺砂率对混合型缓冲材料THM耦合过程的影响分析

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岩土力学 2022年第2期43卷 549-562页

作者：魏天宇王旭宏吕涛胡大伟周辉洪雯中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室湖北武汉430071 中国科学院大学北京100049 中国核电工程有限公司北京100840 武汉电力职业技术学院湖北武汉430000

加入辅助骨料后的混合型缓冲材料在保留了材料密封和防渗能力的同时,克服了纯膨润土导热系数低、施工性差的缺点,作为高放废物处置库缓冲材料的备选材料正在成为新的研究热点。基于室内试验数据,以多孔介质非饱和渗流理论为基础,考虑了... 详细信息

加入辅助骨料后的混合型缓冲材料在保留了材料密封和防渗能力的同时,克服了纯膨润土导热系数低、施工性差的缺点,作为高放废物处置库缓冲材料的备选材料正在成为新的研究热点。基于室内试验数据,以多孔介质非饱和渗流理论为基础,考虑了膨润土湿化膨胀及密度、饱和度、导热系数等材料物理性质参数的实时变化,利用COMSOL Multiphysics软件建立了包含一条巷道及单个井孔的3D网格模型,计算模拟了100 a间屏障系统中膨润土-石英砂混合型缓冲材料的THM多场耦合演化过程,分析了各物理量的时间演化及空间分布规律,并通过不同工况分析了材料湿化膨胀以及掺砂率对屏障系统演化过程的影响。系统中材料温度、饱和度与距固化体、岩壁的距离呈相关性,应力整体以受压为主,变形呈先压缩后膨胀的趋势。其中,膨润土基材料的湿化膨胀作用对温度演化的影响很小,但会略微加速饱和进程,并使材料的应力-应变出现明显的时间演化及区域分布差异。井孔和巷道中靠近岩壁区域的应力上升较快,并且在巷道底板与井孔交界处出现了显著的竖向位移。提高掺量可以有效降低罐体表面温度,增强屏障系统散热能力,降低缓冲材料的历史最大应力,有效控制井孔轴线上的竖向位移,但也会削弱系统的防渗能力。

关键词：高放废物屏障系统湿化膨胀混合型缓冲材料数值模拟多场耦合

Preparation and characterization of a specialized lunar regolith simulant for use in lunar low gravity simulation

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International Journal of Mining Science and Technology 2022年第1期32卷 1-15页

作者： Ruilin Li Guoqing zhou Kang Yan Jun Chen Daqing Chen Shangyue Cai Pin-Qiang Mo state key Laboratory for {2. and Deep Underground engineering China University of Mining and TechnologyXuzhou 221116China School of Mechanics and Civil engineering China University of Mining and TechnologyXuzhou 221116China School of Water Resources and Hydropower engineering Wuhan UniversityWuhan 430072China

Lunar in-situ resource utilization(ISRU)has been put on the agenda by many *** to the special material nature and low gravity environment,the lunar regolith demonstrates significantly different behavior from terrestrial ***,the systematic understanding of its geotechnical behavior is now seriously restricted by the scarcity of lunar regolith and the difficulty in simulating lunar gravity.A new lunar regolith simulant,termed as china University of Mining and Technology Number One(CUMT-1),has been developed to recover properties of the lunar regolith and simulate the lunar gravity by adopting the recently advanced geotechnical magnetic-similitude-gravity model testing(GMMT)*** CUMT-1 simulant was prepared by reproducing the in-situ formation and fragmentation of the lunar matrix,which plays a key role in the irregular particle *** mineralogical compositions,particle morphology and gradation,specific gravity,bulk density,void ratio,shear strength,and compressibility were *** quantifying the magnetization and magnetic-similitude-gravity characteristics,an application of the cone penetration resistance under low gravity was further *** obtained results are compared to the values known for lunar regolith samples and other simulants,which demonstrates promising characteristics for use in geotechnical engineering-based and scientificbased applications,especially considering the influence of lunar gravity.

关键词： Lunar regolith CUMT-1 simulant Low gravity GMMT method ISRU

Characterizing large-scale weak interlayer shear zones using conditional random field theory

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Journal of Rock Mechanics and geotechnical engineering 2023年第10期15卷 2611-2625页

作者： Gang Han Chuanqing Zhang Hemant Kumar Singh Rongfei Liu Guan Chen Shuling Huang Hui zhou Yuting Zhang key Laboratory of geotechnical Mechanics and {2. of the Ministry of Water Resources Changjiang River Scientific Research InstituteWuhanChina state key Laboratory of {2. and geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhanChina University of Chinese Academy of Sciences BeijingChina Department of Petroleum engineering and Geoengineering Rajiv Gandhi Institute of Petroleum TechnologyJaisAmethi229304India state key Laboratory of Water Resources and Hydropower {2. Science Institute of Engineering Risk and Disaster PreventionWuhan UniversityWuhan430072China Institute for Risk and Reliability Leibniz Universität HannoverHannover30167Germany

The shear behavior of large-scale weak intercalation shear zones(WISZs)often governs the stability of foundations,rock slopes,and underground ***,due to their wide distribution,undulating morphology,complex fabrics,and varying degrees of contact states,characterizing the shear behavior of natural and complex large-scale WISZs precisely is *** study proposes an analytical method to address this issue,based on geological fieldwork and relevant experimental *** analytical method utilizes the random field theory and Kriging interpolation technique to simplify the spatial uncertainties of the structural and fabric features for WISZs into the spatial correlation and variability of their mechanical *** Kriging conditional random field of the friction angle of WISZs is embedded in the discrete element software 3DEC,enabling activation analysis of WISZ C2.in the underground caverns of the Baihetan hydropower *** results indicate that the activation scope of WISZ C2.induced by the excavation of underground caverns is approximately 0.5e1 times the main powerhouse span,showing local ***,the overall safety factor of WISZ C2.follows a normal distribution with an average value of 3.697.

关键词： Interlayer shear weakness zone Baihetan hydropower station Conditional random field Kriging interpolation technique Activation analysis

Mechanical behaviours of sandstone containing intersecting fissures under uniaxial compression

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Journal of Rock Mechanics and geotechnical engineering 2022年第2期14卷 460-476页

作者： Fei Xiong Xinrong Liu Xiaohan zhou Guangyi Lin Dongshuang Liu Yafeng Han Bin Xu Chunmei He Zijuan Wang School of Civil engineering Chongqing UniversityChongqing400045China state key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China National Joint engineering Research Center of Geohazards Prevention in the Reservoir Areas Chongqing UniversityChongqing400045China state key Laboratory for {2. and Deep Underground engineering China University of Mining and TechnologyXuzhou221116China College of Architectural engineering Neijiang Normal UniversityNeijiang641100China School of Management Science and engineering Chongqing Technology and Business UniversityChongqing400067China

Predicting rock cracking is important for assessing the stability of underground *** effects of the intersecting angle a and the distribution orientation angleβof intersecting fissures on the uniaxial compressive strength and the failure characteristics of sandstone containing intersecting fissures are investigated through laboratory experiments and two-dimensional particle flow code(PFC2.).The relationship between the mechanical properties of sandstone and the intersecting angle a and the distribution orientation angleβis *** initiation forms and the final failure modes are then categorised and determined via empirical *** addition,the cracking processes of intersecting fissures with different a andβvalues are *** results show that variations in the peak stress,peak strain,average modulus,and crack initiation stress of sandstone containing intersecting fissures show a“moth”shape in the space of the a-β-mechanical *** crack initiation forms are identified:inner tip cracking(usually accompanied by one outer tip cracking)and only outer tips *** failure modes are observed:(1)the main fracture planes are created at the inner tip and one outer tip,and(2.the main fracture planes are formed at the two outer *** main crack evolution processes of sandstone containing intersecting fissures under uniaxial compression are *** for quickly determining the crack initiation form and the failure mode are *** combination of the determination equations for the crack initiation form and the failure mode can be used to predict the crack *** approach for determining the crack evolution processes is hence proposed with acceptable precision.

关键词： Intersecting fissures Sandstone Uniaxial compression Fracture determination Cracking evolution