SLC9A3-AS1调控miR-148a-3p/ROCK1信号轴影响肾癌细胞生物学功能

目的检测lncRNA SLC9A3-AS1在肾透明细胞癌(clear cell renal cell carcinoma,ccRCC)组织与肾癌细胞中的表达水平,探讨其促进肾癌细胞恶性生物学行为的机制。方法应用GEPIA2在线软件(http://gepia2.cancer-pku.cn/)分析TCGA数据库中SLC9A3-AS1在ccRCC组织中的表达水平;采用实时荧光定量聚合酶链反应(qRT-PCR)检测SLC9A3-AS1在不同肾癌细胞系、24例ccRCC组织与癌旁正常肾脏组织中的表达水平;应用细胞增殖/毒性检测试剂盒(cell counting kit-8,CCK-8)和Transwell小室迁移实验检测敲低SLC9A3-AS1表达对肾癌细胞增殖与迁移的影响;应用蛋白质免疫印迹法检测增殖与迁移相关信号通路蛋白的表达水平;采用双荧光素酶报告基因实验验证SLC9A3-AS1与miR-148a-3p/ROCK1轴的靶向调控关系。结果GEPIA2软件分析结果显示,相较正常肾脏组织,SLC9A3-AS1在肾透明细胞癌组织中表达显著上调(P<0.01)。qRT-PCR结果显示,相较癌旁正常肾脏组织,SLC9A3-AS1在24例ccRCC组织中表达显著上调(P<0.01);相较永生化肾小管上皮细胞,SLC9A3-AS1在4种肾癌细胞系中表达均显著上调,以786-O细胞最为显著(P<0.01)。干扰SLC9A3-AS1表达,可显著抑制786-O细胞的增殖与迁移能力,上调E-cadherin的蛋白表达水平,而下调N-cadherin、MMP2的蛋白表达水平(均P<0.05);过表达miR-148a-3p可显著抑制786-O细胞的增殖与迁移能力(P<0.01)。双荧光素酶报告基因检测结果表明,SLC9A3-AS1可特异性结合miR-148a-3p,后者进一步靶向结合ROCK1 mRNA的3′UTR区域;过表达miR-148a-3p可明显下调ROCK1 mRNA的表达水平,敲低miR-148a-3p表达则产生相反的效应;敲低SLC9A3-AS1表达可显著下调786-O细胞中ROCK1 mRNA与蛋白的表达水平(P<0.01);下调miR-148a-3p表达可部分逆转SLC9A3-AS1沉默对786-O细胞增殖与迁移的抑制作用(P<0.05)。结论SLC9A3-AS1在ccRCC中通过调控miR-148a-3p/ROCK1轴发挥促癌作用,有望成为ccRCC的一个新的分子标志物。

3D body解剖软件联合PACS系统在骨科临床实践教学中的应用

目的探讨3D body解剖软件结合医学影像存档与通信系统(PACS)在骨科临床实践教学中的应用效果。方法选择2023年1月至2023年12月在浙江大学医学院附属邵逸夫医院骨科轮转的60名实习生,按照随机数字表法分成实验组和对照组,每组30名。对照组采用传统线上结合线下的混合式教学方法,实验组采用3D body解剖软件联合PACS系统带教模式。在实习期结束时,对两组实习生进行闭卷理论考试与临床实践操作考核,并采用问卷调查方式评估实习生对课程的满意度。结果实验组实习生的理论考试与临床实践操作成绩均高于对照组,差异均有统计学意义(t分别=6.59、4.22,P均<0.05)。实验组实习生在学习兴趣、教学难度、专业能力以及医患沟通能力提升方面的满意度均高于对照组,差异均有统计学意义(χ^(2)分别=9.93、3.77、6.94、8.52,P均<0.05)。结论3D body解剖软件联合PACS系统带教模式运用到骨科实习生的临床教学中,能帮助实习生提高学习兴趣以及医患沟通能力,加强对骨科知识的掌握,降低知识的理解难度,对于提升临床医学教学质量具有重要意义。

Modeling time-dependent mechanical behavior of hard rock considering excavation-induced damage and complex 3D stress states

To investigate the long-term stability of deep rocks,a three-dimensional(3D)time-dependent model that accounts for excavation-induced damage and complex stress state is developed.This model comprises three main components:a 3D viscoplastic isotropic constitutive relation that considers excavation damage and complex stress state,a quantitative relationship between critical irreversible deformation and complex stress state,and evolution characteristics of strength parameters.The proposed model is implemented in a self-developed numerical code,i.e.CASRock.The reliability of the model is validated through experiments.It is indicated that the time-dependent fracturing potential index(xTFPI)at a given time during the attenuation creep stage shows a negative correlation with the extent of excavationinduced damage.The time-dependent fracturing process of rock demonstrates a distinct interval effect of the intermediate principal stress,thereby highlighting the 3D stress-dependent characteristic of the model.Finally,the influence of excavation-induced damage and intermediate principal stress on the time-dependent fracturing characteristics of the surrounding rocks around the tunnel is discussed.

3D DEM simulation of hard rock fracture in deep tunnel excavation induced by changes in principal stress magnitude and orientation

To achieve the loading of the stress path of hard rock,the spherical discrete element model(DEM)and the new flexible membrane technology were utilized to realize the transient loading of three principal stresses with arbitrary magnitudes and orientations.Furthermore,based on the deep tunnel of China Jinping Underground Laboratory II(CJPL-II),the deformation and fracture evolution characteristics of deep hard rock induced by excavation stress path were analyzed,and the mechanisms of transient loading-unloading and stress rotation-induced fractures were revealed from a mesoscopic perspective.The results indicated that the stressestrain curve exhibits different trends and degrees of sudden changes when subjected to transient changes in principal stress,accompanied by sudden changes in strain rate.Stress rotation induces spatially directional deformation,resulting in fractures of different degrees and orientations,and increasing the degree of deformation anisotropy.The correlation between the degree of induced fracture and the unloading magnitude of minimum principal stress,as well as its initial level is significant and positive.The process of mechanical response during transient unloading exhibits clear nonlinearity and directivity.After transient unloading,both the minimum principal stress and minimum principal strain rate decrease sharply and then tend to stabilize.This occurs from the edge to the interior and from the direction of the minimum principal stress to the direction of the maximum principal stress on theε1-ε3 plane.Transient unloading will induce a tensile stress wave.The ability to induce fractures due to changes in principal stress magnitude,orientation and rotation paths gradually increases.The analysis indicates a positive correlation between the abrupt change amplitude of strain rate and the maximum unloading magnitude,which is determined by the magnitude and rotation of principal stress.A high tensile strain rate is more likely to induce fractures under low minimum principal stress.

3D Body解剖软件结合CBL教学法在骨科实习生临床带教中的应用

目的:探讨3D body解剖软件结合CBL教学法在骨科实习生临床带教中的应用效果。方法:随机选取2022年1月~2023年12月在我科室实习的36名骨科实习生为研究对象,随机分为观察组和对照组,对照组采用CBL教学模式,观察组在对照组的教学模式上运用3D body解剖软件。教学结束后,比较两组学生的理论知识考试成绩,PPT汇报成绩以及教学满意度。结果:观察组学生理论知识考核成绩、PPT汇报成绩、教学满意度明显高于对照组,差异具有显著性(P < 0.05)。结论:3D body解剖软件结合CBL教学法应用于骨科实习生临床带教,可以有效提高学生成绩,调动学生积极性及自主学习能力,提升教学满意度。

Heterogeneous information phase space reconstruction and stability prediction of filling body–surrounding rock combination

Traditional research believes that the filling body can effectively control stress concentration while ignoring the problems of unknown stability and the complex and changeable stress distribution of the filling body–surrounding rock combination under high-stress conditions.Current monitoring data processing methods cannot fully consider the complexity of monitoring objects,the diversity of monitoring methods,and the dynamics of monitoring data.To solve this problem,this paper proposes a phase space reconstruction and stability prediction method to process heterogeneous information of backfill–surrounding rock combinations.The three-dimensional monitoring system of a large-area filling body–surrounding rock combination in Longshou Mine was constructed by using drilling stress,multipoint displacement meter,and inclinometer.Varied information,such as the stress and displacement of the filling body–surrounding rock combination,was continuously obtained.Combined with the average mutual information method and the false nearest neighbor point method,the phase space of the heterogeneous information of the filling body–surrounding rock combination was then constructed.In this paper,the distance between the phase point and its nearest point was used as the index evaluation distance to evaluate the stability of the filling body–surrounding rock combination.The evaluated distances(ED)revealed a high sensitivity to the stability of the filling body–surrounding rock combination.The new method was then applied to calculate the time series of historically ED for 12 measuring points located at Longshou Mine.The moments of mutation in these time series were at least 3 months ahead of the roadway return dates.In the ED prediction experiments,the autoregressive integrated moving average model showed a higher prediction accuracy than the deep learning models(long short-term memory and Transformer).Furthermore,the root-mean-square error distribution of the prediction results peaked at 0.26,thus outperforming the no-prediction method in 70%of the cases.

Investigation on mechanical properties regulation of rock-like specimens based on 3D printing and similarity quantification

3D printing is widely adopted to quickly produce rock mass models with complex structures in batches,improving the consistency and repeatability of physical modeling.It is necessary to regulate the mechanical properties of 3D-printed specimens to make them proportionally similar to natural rocks.This study investigates mechanical properties of 3D-printed rock analogues prepared by furan resin-bonded silica sand particles.The mechanical property regulation of 3D-printed specimens is realized through quantifying its similarity to sandstone,so that analogous deformation characteristics and failure mode are acquired.Considering similarity conversion,uniaxial compressive strength,cohesion and stress–strain relationship curve of 3D-printed specimen are similar to those of sandstone.In the study ranges,the strength of 3D-printed specimen is positively correlated with the additive content,negatively correlated with the sand particle size,and first increases then decreases with the increase of curing temperature.The regulation scheme with optimal similarity quantification index,that is the sand type of 70/140,additive content of 2.5‰and curing temperature of 81.6℃,is determined for preparing 3D-printed sandstone analogues and models.The effectiveness of mechanical property regulation is proved through uniaxial compression contrast tests.This study provides a reference for preparing rock-like specimens and engineering models using 3D printing technology.

Failure mechanism and safety control technology of a composite strata roadway in deep and soft rock masses:a case study

The construction of coal mines often encounters deep composite soft rock roadways,which is characterized by significant deformation and poor stability.To deeply study the failure mechanism and large deformation challenges of a composite strata roadway in deep and soft rock masses,a numerical model of 3DEC tetrahedral blocks was established based on the method of rock quality designation(RQD).The results showed that original support cannot prevent asymmetric failure and large deformation due to the adverse geological environment and unsuitable support design.According to the failure characteristics,a coupling support of“NPR bolt/cable+mesh+shotcrete+steel pipe”was proposed to control the stability of the surrounding rock.The excellent mechanical properties of large deformation(approximately 400 mm)and high constant resistance force(bolt with 180 k N;cable with 350 k N)were evaluated by the tensile tests.The numerical results showed that the maximum deformation was minimized to 243 mm,and the bearing capacity of the surrounding rock of the roadway was enhanced.The field test results showed that the maximum deformation of the surrounding rock was 210 mm,and the forces of the NPR bolt and cable were stable at approximately 180 k N and 350 k N,respectively.This demonstrated the effectiveness of the coupling support with the NPR bolt and cable,which could be a guiding significance for the safety control of large deformation and failure in deep composite soft rock roadways.

Method of fabricating artificial rock specimens based on extrusion free forming(EFF)3D printing

Three-dimensional(3D)printing technology has been widely used to create artificial rock samples in rock mechanics.While 3D printing can create complex fractures,the material still lacks sufficient similarity to natural rock.Extrusion free forming(EFF)is a 3D printing technique that uses clay as the printing material and cures the specimens through high-temperature sintering.In this study,we attempted to use the EFF technology to fabricate artificial rock specimens.The results show the physico-mechanical properties of the specimens are significantly affected by the sintering temperature,while the nozzle diameter and layer thickness also have a certain impact.The specimens are primarily composed of SiO_(2),with mineral compositions similar to that of natural rocks.The density,uniaxial compressive strength(UCS),elastic modulus,and tensile strength of the printed specimens fall in the range of 1.65–2.54 g/cm3,16.46–50.49 MPa,2.17–13.35 GPa,and 0.82–17.18 MPa,respectively.It is capable of simulating different types of rocks,especially mudstone,sandstone,limestone,and gneiss.However,the simulation of hard rocks with UCS exceeding 50 MPa still requires validation.

Anisotropic creep behavior of soft-hard interbedded rock masses based on 3D printing and digital imaging correlation technology

Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.

“3D Body”系统在高职院校专业课程教育中的应用研究

本文研究“3D Body”人体解剖系统在人体解剖学与组织胚胎学教学中的应用效果。在传统实验教学的基础上进行了突破创新,研究数字化虚拟教学模式的可行性。通过“3D Body”人体解剖系统在人体解剖学与组织胚胎学教学中的应用,学生的理论课成绩和实验课成绩的及格率和良好率均有提高;实验组满意度95%(57/60)高于对照组81.66%(49/60);试验组考试成绩、教学效果均高于对照组(P<0.05)。“3D Body”人体解剖系统在人体解剖学与组织胚胎学教学中的应用可提升教学满意度,提高学生学习的兴趣、学习成绩和教学效果,具有推广价值。

3D body软件在护理实习生肌内注射培训中的应用

目的探讨3D body软件在儿科专科护理实习生肌内注射培训中的应用。方法选取2021年6月至2022年5月在江西省儿童医院实习的160名护生,根据随机数字表法将其分为对照组和实验组,每组各80名。对照组使用常规教学方法以3例临床案例进行培训;实验组在对照组培训方案基础上应用3D body软件。比较两组护生培训前后的技能考核成绩、操作过程中对肌内注射部位选择的准确性和定位的准确率以及对培训方法的效果评价。结果培训后实验组护生的肌内注射技能考核成绩显著优于对照组(P<0.05),注射部位定位准确率显著高于对照组(P<0.05),实验组护生对培训方法的兴趣及满意度明显提高。结论将3D body软件用于儿科护生的肌内注射技能培训,有助于深化护生对肌内注射部位体表标志及骨性标志的认识,提高肌内注射技能考核成绩;同时激发护生的学习积极性,增强对该技能操作的自信心。

GCNT3通过PI3K/Akt/mTOR和RhoA/ROCK/Cofilin途径促进肝癌细胞增殖、迁移和侵袭(英文)

β-1,3-半乳糖-O-糖基-糖蛋白β-1,6-N-乙酰氨基葡萄糖转移酶(β-1,3-galactosyl-O-glycosyl-glycoproteinβ-1,6-N-acetylglucosaminyltransferase,GCNT3)是黏液蛋白质生物合成中不可缺少的一类N-乙酰葡萄糖转移酶。越来越多的证据表明,GCNT3的异常表达与肿瘤的侵袭以及病人的生存率有关,然而相关的研究仍较少报道。本研究旨在揭示GCNT3在调控肝细胞癌进程中的潜在机制。本研究首先利用高通量基因表达数据库(Gene Expression Omnibus,GEO)和癌症基因组图谱(Cancer Genome Atlas databases,TCGA)数据库分析肝癌和正常组织中GCNT3的mRNA表达水平,结果表明,肝癌组织中GCNT3的mRNA表达水平高于正常组织(P≤0.001)。同时利用免疫组化、Western印迹进一步分析了肝癌组织、癌旁组织、正常组织中GCNT3蛋白的表达,发现有30%肝癌组织GCNT3表达水平高于癌旁组织和正常组织。随后,在肝癌细胞系HCCLM3和Huh7细胞中,采用CCK-8、平板克隆、划痕实验、Transwell实验分析GCNT3对肝癌细胞增殖、迁移和侵袭能力的影响,结果显示,敲低GCNT3可抑制肝癌细胞的增殖、迁移和侵袭,而过表达GCNT3发挥相反作用。细胞周期和Western印迹结果显示,GCNT3调控G_(0/)G_1期关键蛋白质的表达来促进肝癌细胞周期G_1/S的转换。进一步探究发现,GCNT3可能通过激活PI3K/AKT/mTOR信号通路促进细胞增殖;以及GCNT3上调RhoA/ROCK/Cofilin通路关键蛋白质的表达来促进F-肌动蛋白(F-actin)的形成,从而参与细胞的迁移和侵袭。总之,本研究通过对GCNT3在肝癌细胞中的功能分析,初步证明,GCNT3与肝癌细胞增殖、迁移和侵袭中的功能有关,证实了GCNT3在肝癌临床治疗中的潜在价值,为肝癌治疗和诊断提供了新思路。

Application and prospects of 3D printing in physical experiments of rock mass mechanics and engineering:materials,methodologies and models

The existence of joints or other kinds of discontinuities has a dramatic efect on the stability of rock excavations and engineering.As a result,a great challenge in rock mass mechanics testing is to prepare rock or rock-like samples with defects.In recent years,3D printing technology has become a promising tool in the feld of rock mass mechanics and engineering.This study frst reviews and discusses the research status of traditional test methods in rock mass mechanics tests of making rock samples with defects.Then,based on the comprehensive analysis of previous research,the application of 3D printing technology in rock mass mechanics is expounded from the following three aspects.The frst is the printing material.Although there are many materials for 3D printing,it has been found that 3D printing materials that can be used for rock mass mechanics research are very limited.After research,we summarize and evaluate printing material that can be used for rock mass mechanics studies.The second is the printing methodology,which mainly introduces the current application forms of 3D printing technology in rock mass mechanics.This includes printed precise casting molds and one-time printed samples.The last one is the printing model,which includes small-scale samples for mechanical tests and large-scale physical models.Then,the benefts and drawbacks of using 3D printing samples in mechanical tests and the validity of their simulation of real rock are discussed.Compared with traditional rock samples collected in nature or synthetic rock-like samples,the samples made by 3D printing technology have unique advantages,such as higher test repeatability,visualization of rock internal structure and stress distribution.There is thus great potential for the use of 3D printing in the feld of rock mass mechanics.However,3D printing materials also have shortcomings,such as insufcient material strength and accuracy at this stage.Finally,the application prospect of 3D printing technology in rock mass mechanics research is proposed.

Notch3介导RhoA/ROCK/Hif1α轴对心肌梗死心功能的影响

目的分析Notch3介导RhoA/ROCK/Hif1α轴对心肌梗死(MI)心功能的影响。方法将45只雄性SD大鼠随机分为假手术组、模型组和Notch3过表达组三组,每组各15只。大鼠心肌注射Notch3慢病毒过表达后构建MI模型。术后12周检测心功能及心脏血流动力学指标,观察心肌组织结构,并检测心肌组织Notch3和RhoA/ROCK/Hif1α轴相关蛋白水平。结果与假手术组比较,模型组大鼠心肌组织Notch3表达水平、左心室射血分数(LVEF)、左心室舒张末压(LVEDP)显著降低,左心室收缩末期内径(LVESD)、左心室舒张末期内径(LVEDD)、左心室收缩末压(LVESP)、左心室压力最大上升速率(LV+dp/dtmax)、左心室压力最大下降速率(LV-dp/dtmax)、心肌组织RhoA、ROCK1、ROCK2、Hif1α表达水平显著增加(P<0.05);Notch3过表达组大鼠LVESD和LVEDD显著小于模型组,心肌组织Notch3表达水平、LVEF、LVEDP显著高于模型组(P<0.05);LVESP、LV+dp/dtmax和LV-dp/dtmax、心肌组织RhoA、ROCK1、ROCK2、Hif1α表达水平显著降低(P<0.05)。结论Notch3过表达可能通过RhoA/ROCK/Hif1α轴抑制MI后心肌代偿性肥厚,逆转左心室扩大,改善心功能。

Damage evolution of rock-encased-backfill structure under stepwise cyclic triaxial loading

Rock-encased-backfill(RB)structures are common in underground mining,for example in the cut-andfill and stoping methods.To understand the effects of cyclic excavation and blasting activities on the damage of these RB structures,a series of triaxial stepwise-increasing-amplitude cyclic loading experiments was conducted with cylindrical RB specimens(rock on outside,backfill on inside)with different volume fractions of rock(VF=0.48,0.61,0.73,and 0.84),confining pressures(0,6,9,and 12 MPa),and cyclic loading rates(200,300,400,and 500 N/s).The damage evolution and meso-crack formation during the cyclic tests were analyzed with results from stress-strain hysteresis loops,acoustic emission events,and post-failure X-ray 3D fracture morphology.The results showed significant differences between cyclic and monotonic loadings of RB specimens,particularly with regard to the generation of shear microcracks,the development of stress memory and strain hardening,and the contact forces and associated friction that develops along the rock-backfill interface.One important finding is that as a function of the number of cycles,the elastic strain increases linearly and the dissipated energy increases exponentially.Also,compared with monotonic loading,the cyclic strain hardening characteristics are more sensitive to rising confining pressures during the initial compaction stage.Another finding is that compared with monotonic loading,more shear microcracks are generated during every reloading stage,but these microcracks tend to be dispersed and lessen the likelihood of large shear fracture formation.The transition from elastic to plastic behavior varies depending on the parameters of each test(confinement,volume fraction,and cyclic rate),and an interesting finding was that the transformation to plastic behavior is significantly lower under the conditions of 0.73 rock volume fraction,400 N/s cyclic loading rate,and 9 MPa confinement.All the findings have important practical implications on the ability of backfill to support underground excavations.

电针抑制NLRP3炎性小体活化改善缺血性脑卒中的机制研究

目的观察电针对缺血性脑卒中大鼠神经行为学及脑组织结构的影响,探讨电针通过调控NOD样受体热蛋白结构域相关蛋白3(NOD-like receptor thermal protein domain associated protein 3,NLRP3)炎性小体途径改善缺血性脑卒中大鼠神经功能的机制。方法36只健康雄性SD大鼠采用随机数字表随机分为假手术组12只及手术组24只,手术组大鼠采用Longa等改良线栓法制备大鼠脑缺血再灌注损伤(MCAO)模型。术后2 h行神经行为学评分,造模成功的大鼠再随机分为模型组及电针组。电针组予电针“曲池”“足三里”连续干预7 d,假手术组及模型组不做干预。干预完成后分别评估各组大鼠神经功能缺损情况,HE染色观察脑组织病理学变化,QPCR及Western blot法检测炎性小体相关蛋白NLRP3、ASC、Caspase-1的表达水平,ELISA检测各组大鼠血清IL-1β和IL-18炎性因子表达。结果与假手术组相比,模型组大鼠神经功能评分均显著提高,差异有高度统计学意义(P<0.01),脑组织缺血皮质区神经元胞体缩小变形,核固缩明显,大鼠脑组织缺血周围区炎性因子相关蛋白NLRP3、ASC、Caspase-1的mRNA及蛋白表达水平升高,差异有高度统计学意义(P<0.01),血清IL-1β和IL-18炎症因子表达增加,差异有高度统计学意义(P<0.01);经电针干预7 d后,电针组神经评分功能较模型组显著下降,差异有统计学意义(P<0.05),所见的病理损伤减少;炎性小体相关蛋白NLRP3、ASC、Caspase-1的表达下降,差异有统计学意义(P<0.05),且电针下调了血清IL-1β和IL-18的表达,差异有统计学意义(P<0.05)。结论电针“曲池”“足三里”可减轻缺血性脑卒中大鼠神经功能缺损症状,减少脑组织病理损伤,下调NLRP3、ASC、Caspase-1表达水平,其机制可能与调控NLRP3炎性小体途径抗细胞焦亡,减轻脑缺血再灌注损伤有关。

3-D modeling of rock burst in pillar No. 19 of Fetr6 chromite mine

Fetr6 is an underground mine in which chromite is extracted using stope and pillar mining method. Despite of all improving works such as roof supporting and replacing of ore pillars with concrete pillars, pillar No. 19 failed and other pillars failed progressively as a domino effect and 4000 m2 of mine collapsed within a few minutes, consequently. For detail investigation, two 3-D numerical models were developed by 3Dec. The first, a base model, was used for estimation of stress on pillars just before failure and the other for investigation of rock burst in pillar No. 19. The results show that discontinuity parameters such as friction angle and shear stiffness is critical parameters in this pillar failure. In addition, it indicates that W/H ratio equal 0.3, the lack of ore extraction strategy and inadequate roof support are the major reasons for this failure. In this paper, the procedure of study was described.

Effect of surface retaining elements on rock stability:laboratory investigation with sand powder 3D printing

This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analogue prismatic specimens for conducting this investigation. Uniaxial compression tests with acoustic emission (AE) and digital image correlation techniques have been conducted on 3DP specimens bolted with diferent SREs. The results demonstrate that the strength and modulus of elasticity of the bolted specimens show a positive correlation with the area of the SRE;the AE characteristics of the bolted specimens are higher than those of the unbolted specimen, but they decrease with an increase in SRE area, thus further improving the integrity of the bolted specimens. The reinforcement efect of SREs on the surrounding rock of roadways is further analyzed using numerical modelling and feld test. The results provide a better understanding of the role of SREs in rock bolting and the optimization of rock bolting design. Furthermore, they verify the feasibility of 3DP for rock analogues in rock mechanics tests.

Method for visualizing the shear process of rock joints using 3D laser scanning and 3D printing techniques

This study presents a visualized approach for tracking joint surface morphology.Three-dimensional laser scanning(3DLS)and 3D printing(3DP)techniques are adopted to record progressive failure during rock joint shearing.The 3DP resin is used to create transparent specimens to reproduce the surface morphology of a natural joint precisely.The freezing method is employed to enhance the mechanical properties of the 3DP specimens to reproduce the properties of hard rock more accurately.A video camera containing a charge-coupled device(CCD)camera is utilized to record the evolution of damaged area of joint surface during the direct shear test.The optimal shooting distance and shooting angle are recommended to be 800 mm and 40?,respectively.The images captured by the CCD camera are corrected to quantitatively describe the damaged area on the joint surface.Verification indicates that this method can accurately describe the total sheared areas at different shear stages.These findings may contribute to elucidating the shear behavior of rock joints.