Failure behavior of a rock-coal-rock combined body with a weak coal interlayer

Using an MTS 815 testing machine,the deformation and failure behavior of a rock-coal-rock combined body containing a weak coal interlayer has been investigated and described in this paper.Uniaxial loading leads to the appearance of mixed cracks in the coal body which induce instability and lead to bursts in coal.If the mixed crack propagates at a sufficiently high speed to carry enough energy to damage the roof rock,then coal and rock bursts may occur-this is the main mechanism whereby coal bumps or coal and rock bursts occur after excavation unloading.With increasing confining pressure,the failure strength of a rock-coal-rock combined body gradually increases,and the failure mechanism of the coal interlayer also changes,from mixed crack damage under low confining pressures,to parallel crack damage under medium confining pressures,and finally to single shear crack damage or integral mixed section damage under high confining pressures.In general,it is shown that a weak coal interlayer changes the form of overall coal damage in a rock-coal-rock combined body and reduces the overall stability of a coal body.Therefore,the whole failure behavior of a rock-coal-rock combined body in large cutting height working faces is controlled by these mechanisms.

Compression failure conditions of concrete-granite combined body with different roughness interface

Bedrock and concrete lining are typical composite structures in the engineering field and the stability of the geological body and engineering body is directly connected to the mechanical properties of the composite body.Under this background,the study provides the transverse isotropic equivalent model of concrete-granite double-layer composite based on the notion of strain energy equivalence.Assuming that the strength failure of concrete and granite meets the Mohr-Coulomb criterion,then the strength failure model of the combined body considering the joint roughness coefficient(JRC)is derived,and the influences of JRC,the height ratio of concrete to granite,and confining pressure on the strength failure characteristics of the combined body are emphatically analyzed.Finally,the model applicability is illustrated by the uniaxial and triaxial compression tests on concrete monomer,granite monomer and concretegranite composite samples(CGCSs)with different JRCs.The results revealed that the compressive strength of the composite is closer to the concrete with lower strength in the combined body under different confining pressures.Adding interface roughness causes to raise the compressive strength of the composite due to interfacial adhesion between concrete and granite,and a slowing growth trend is observed in compressive strength as roughness.The model can provide a certain reference for the stability design and evaluation of engineering rock mass.

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.

A novel binary effective medium model to describe the prepeak stressstrain relationship of combined bodies of rock-like material and rock

Combined bodies of rock-like material and rock are widely encountered in geotechnical engineering,such as tunnels and mines.The existing theoretical models describing the stress-strain relationship of a combined body lack a binary feature.Based on effective medium theory,this paper presents the governing equation of the“elastic modulus”for combined and single bodies under triaxial compressive tests.A binary effective medium model is then established.Based on the compressive experiment of concretegranite combined bodies,the feasibility of determining the stress threshold based on crack axial strain is discussed,and the model is verified.The model is further extended to coal-rock combined bodies of more diverse types,and the variation laws of the compressive mechanical parameters are then discussed.The results show that the fitting accuracy of the model with the experimental curves of the concretegranite combined bodies and various types of coal-rock combined bodies are over 95%.The crack axial strain method can replace the crack volumetric strain method,which clarifies the physical meanings of the model parameters.The variation laws of matrix parameters and crack parameters are discussed in depth and are expected to be more widely used in geotechnical engineering.

Experimental Study on Dynamic Mechanical Properties of Sprayed Concrete-Surrounding Rock Combined Body

To investigate the dynamic response problem of the double medium formed by the adherence of sprayed concrete and surrounding rock in the tunnel,a split Hopkinson pressure bar of 75 mm in diameter was adopted at the ages of 3,7 and 10 d.Experimental results showed that dynamic compressive strength and dynamic increase factors(DIF)of the combined bodies increase with the strain rate.With the growth of strain rate,the critical strain of the combined bodies first increases,then deceases.Furthermore,the combined bodies of 3 d reveal the plastic property and brittle property for 7 d and 10 d when the strain rate is over 80/s.The failure characteristic of the sprayed concrete changes from tearing strain damage to crushing damage as the growth of strain rate,and the failure characteristic of rock presents the tensile failure mode as demonstrated by the scanning electron microscope(SEM).

Firey linear combinations of convex bodies

For convex bodies, the Firey linear combinations were introduced and studied in several papers. In this paper the mean width of the Firey linear combinations of convex bodies is studied, and the lower bound of the mean width of the Firey linear combinations of convex body and its polar body is given.

Combined Effects of Exposure to Noise and Vibration on Human Postural Equilibrium under Simulated Driving Conditions

There is little information about drivers’body balance responses to combined exposure of noise and vibration.To fill the gap,this study aims to investigate the combined effects of exposure to noise and whole-body vibration(WBV)on the body balance under simulated driving conditions.For this purpose,30 male participants were exposed to noise level at 85 dB(A)and two vibration levels(0.87 and 1.3 m/s^(2))in five sessions.The design of the study was repeated-measures,and it attempted to assess the effects of 40 minutes of exposure to noise and/or WBV.Moreover,the participants’fatigue was measured with the Borg scale(CR 10).The findings revealed there was a significant change in body sway after WBV and combined noise and WBV exposure(p<0.05).However,no significant difference was found in exposure to noise alone(p>0.05).The effect sizes of exposure to noise,WBV(1.3 m/s^(2)),and combined noise and WBV(1.3 m/s^(2))on body balance were 0.035,0.425,and 0.635,respectively.Also,single exposure to WBV caused more fatigue than single exposure to noise(p<0.05).Combined noise and WBV exposure descriptively caused more fatigue in comparison with the influence of WBV alone.The study concluded that the combined effects of exposure to noise and vibration are more than the sum of them.So,some synergistic effects may be observed in human body balance.It is essential to increase drivers’awareness and revise current health care interventions about new possible effects of combined exposures.

特殊体型男西装高级定制虚拟仿真实验建设与实践

传统的特殊体型男西装高级定制实验教学存在特殊体型模特缺乏、西装款式单一、成本高、周期长及教学效果差等问题。基于虚拟仿真技术,文章对这一重点与难点综合实验进行了建设实践,构建了虚实结合的线上线下混合式实验教学体系,并在实际教学中实施。该虚拟仿真实验教学体系可引导服装专业学生通过探究式学习实现理论知识向工程实践应用的转化,培养学生解决复杂工程问题的能力。

循环水岩作用下煤岩组合体力学响应及劣化机制

煤矿地下水库的建立解决了我国西部干旱-半干旱生态脆弱区的缺水问题。地下水库不断进行着蓄水-抽水,地下水库水位的反复升降对水库坝体产生反复损伤作用,而半煤岩坝体、煤岩夹矸坝体为地下水库常见的坝体。基于此,设计进行了不同“干燥-饱和”循环次数的砂岩-煤组合体不同围压下的轴向压缩试验,分析循环浸水作用下煤岩组合体力学特性劣化规律和劣化机制。结果表明:(1)随着循环次数的增加,组合体的饱和含水率逐渐增大。饱和含水率与循环次数呈对数关系。(2)随着循环次数的增加,应力-应变曲线压密阶段增长,弹性阶段斜率减小,峰值应力降低,峰值应变增大,屈服阶段愈加明显,应力跌落变缓。(3)随着循环次数的增加,组合体抗压强度逐渐降低,循环1~3次,抗压强度劣化幅度较为明显。抗压强度阶段劣化度具有非均匀性。(4)循环1~5次,黏聚力下降了70.87%,内摩擦角下降了60.65%。(5)循环1~3次,组合体弹性模量下降了53.06%,变形模量下降了61.10%。(6)循环浸水作用下,试样微观裂纹逐渐发育,矿物颗粒由原来的棱角分明的多边形向浑圆形逐渐发展,大的矿物颗粒逐渐崩解为小颗粒,颗粒间胶结作用逐渐弱化,由紧凑致密结构向松散软弱结构转变。(7)循环浸水作用下,水岩发生反复的物理、化学、力学作用,对煤岩产生反复损伤,最终导致宏观力学特性的劣化。

组合运动干预对肥胖女青少年身体成分、心血管风险因素及心肺适能影响的研究

背景目前,全球范围内肥胖儿童青少年数量急剧增加,其中,5~19岁人群肥胖患病率约增加了8倍,2~4岁儿童肥胖患病率约增加了1倍。运动干预对于改善肥胖和增强心肺适能具有重要影响。但缺乏组合运动干预对14~16岁肥胖女青少年影响的研究。目的探讨12周组合运动干预对肥胖女青少年身体成分、心血管风险因素及心肺适能的影响。方法于2022年5—7月在山东曲阜市选取14~16岁肥胖女青少年48名作为研究对象,将48名研究对象进行编号,然后利用随机数字分为试验组(24名)和对照组(24名)。试验组根据纳排标准最后纳入20名女生,整个干预过程持续12周,包括跳绳运动干预和跆拳道运动干预;而对照组在整个12周中不进行任何运动干预和其他饮食或者药物干预。分别在12周运动干预前和运动干预后检测受试者身高、体质量、体脂率、腰围、BMI、血压、空腹血糖(FPG)、胰岛素、胰岛素抵抗指数(HOMA-IR)及最大摄氧量(VO_(2max))等,并比较两组及干预前后各指标的差异。采用Pearson相关性分析探讨肥胖女青少年体脂率、腰围与VO_(2max)的相关性。结果干预前,两组女生年龄、身高、体质量、体脂率、腰围、BMI、收缩压(SBP)、舒张压(DBP)、脉压、FPG、胰岛素、HOMAIR、最大完成次数(Laps)、最大跑速(MAS)、VO_(2max)比较,差异均无统计学意义(P>0.05);12周运动干预后,试验组女生体脂率、腰围、SBP、DBP、FPG、胰岛素、HOMA-IR均低于对照组,而Laps、MAS、VO_(2max)高于对照组(P<0.05);与干预前比较,12周运动干预后试验组女生体脂率、腰围、SBP、DBP、FPG、胰岛素、HOMA-IR均降低,而Laps、MAS、VO_(2max)升高(P<0.05)。相关性分析结果显示,肥胖女青少年体脂率、腰围与VO_(2max)呈负相关(r=-0.55,P<0.001;r=-0.41,P<0.001)。结论12周组合运动干预能够改善肥胖女青少年身体成分和心血管风险因素,同时也能够通过增加VO_(2max)来增强心肺适能。

固始鸡A系与矮小贵妃鸡杂交F_(1)代生长性能探究及生长曲线拟合

试验旨在探究固始鸡A系与矮小贵妃鸡杂交后代的生长发育规律,选育出最优杂交组合。试验以固始鸡A系和矮小贵妃鸡进行正反交后代为素材,每周测量体重,90日龄和110日龄分别测量体尺性状并进行相关性分析,使用Logistic、Gompertz和Von-Bertalanffy三种模型拟合其生长曲线。结果显示,前4周,AG公母鸡与GA公母鸡的生长速度差异不大,4周龄以后,生长速度出现差异分化,GA公鸡的拐点周龄为8周,AG公鸡的拐点周龄为7.2周。GA母鸡的拐点周龄为7.9周,AG母鸡的拐点周龄为6.7周。90日龄时,GA母鸡的体重、体斜长、胫长、胸深优于AG母鸡,110日龄时,GA公鸡的体斜长优于AG公鸡,与AG群体相比,GA群体体尺性状较为优良。GA群体体重与体斜长和骨盆宽存在显著相关(P<0.05)。Gompertz模型对AG公鸡与GA母鸡这两个群体拟合效果更佳,Logistic曲线对AG母鸡和GA公鸡这两个群体拟合效果更佳。综上所述,矮小贵妃鸡♂×固始鸡A系♀为最优杂交组合。

裂隙煤岩组合体单轴压缩力学响应及失稳机制

煤岩系统中煤层与岩层之间的层间薄弱带是裂隙分布的主要区域,这些裂隙贯穿于两岩层,严重影响着煤岩系统的力学性质与工程稳定。为探究贯穿裂隙对煤岩系统力学性质的影响,对5种裂隙长度、5种裂隙角度的裂隙煤岩组合体开展轴向加载试验,结果表明:(1)随裂隙长度的增加,抗压强度、弹性模量、峰值能量、冲击能量指数呈线性减小。随裂隙角度的增大,抗压强度、弹性模量、峰值能量、冲击能量指数先减小后增大。(2)试样破坏声发射活动均经历平静期、活跃期、剧烈期3个阶段。随裂隙长度的增加,声发射累计能量先增加后减小。随裂隙角度的增大,声发射峰值能量和累计能量先增大后减小。(3)裂隙长度和角度对翼裂纹、次生倾斜裂纹、次生共面裂纹、斜裂纹、次生衍生裂纹、翼裂纹衍生裂纹、远场裂纹以及剥落现象有一定影响。(4)随裂隙长度的增加,黏聚力和内摩擦角逐渐降低。随裂隙角度的增加,黏聚力和内摩擦角先减小后增大。(5)构建了考虑裂隙长度和裂隙角度的Drucker-Prager强度准则,合理性验证发现:试样误差在1.367%~5.055%合理范围之内。(6)基于耗散结构理论,分析了组合体失稳破坏机制,组合体破坏主要经历了准稳态、亚稳态、失稳、新稳态4个阶段;构建了裂隙煤岩组合体能量运移模型,分析了裂隙煤岩组合体失稳破坏过程中的能量运移规律。裂隙两端是能量积聚的主要区域,煤组分裂隙端破坏时,一部分能量运移到岩石组分裂隙端,以岩石组分破坏或变形的形式释放出去。研究结果可为探究深部煤岩力学性质、揭示煤岩动力灾害发生机制提供有益参考。

三维静载与循环冲击共同作用下组合煤岩体力学特性试验研究

为进一步研究循环冲击载荷下煤岩体的力学特性,以岩-煤-岩结构试样为研究对象,利用改进后霍普金森压杆试验系统,开展三维静载与循环动态冲击试验,研究冲击入射能及围压对岩-煤-岩结构试样的强度、变形及破坏特征的影响。研究结果表明:相同围压下,总循环次数随冲击入射能的增加而逐渐减少;相同入射能下,总冲击次数随围压的增大而增加;相同围压下,平均应变率随着冲击次数、冲击入射能的增加而逐渐增加;相同入射能下,围压9 MPa时应变率较低且前期增长幅值较为缓慢,围压3 MPa时应变率较高且增长速度较快;峰值应力、变形模量随入射能增加而逐渐递增,随冲击次数增加而逐渐递减;相同入射能下,峰值应力及变形模量随围压的增大而增加;相同围压下,峰值应力与应变率呈幂函数递减,变形模量与应变率呈线性函数递减;循环冲击下,煤岩体破碎程度明显高于单次冲击,破坏主体是煤,破坏形式为剪切-拉伸复合破坏,并且具有明显的率相关性,随着冲击入射能的增加或者围压的减少,煤碎块尺寸较小且块数较多。研究结果可为深部煤岩体动力灾害控制提供理论参考。

全身动态^(18)F-FDG PET/CT Patlak多参数显像监测PD-1抗体联合放射治疗对小鼠B16F10黑色素瘤的协同作用及远隔效应

目的 采用全身动态^(18)F-脱氧葡萄糖正电子发射计算机断层显像(^(18)F-FDG PET/CT) Patlak多参数显像技术,监测和评价程序性死亡受体-1(PD-1)免疫检查点单抗与放射联合治疗的协同抗肿瘤效应。方法 建立B16F10黑色素瘤小鼠双瘤模型,按照随机数字表法分为4组:空白对照组、PD-1单抗组、单纯放疗组、PD-1单抗+放疗(联合治疗)组,每组6只,分别于治疗前和治疗完成后24 h对小鼠行全身动态^(18)F-FDG PET/CT Patlak多参数显像。显像完后之后,分析比较四组肿瘤最大标准化摄取值(SUV_(max))、葡萄糖净摄取速率(MR_(FDG))的变化,以颈椎脱臼的方法处死小鼠,取出四组肿瘤进行苏木精-伊红(HE)染色及肿瘤浸润T淋巴细胞(CD8)、细胞核增殖抗原(Ki67)免疫组化分析肿瘤组织免疫细胞浸润情况及肿瘤组织增殖情况。治疗期间记录远端肿瘤体积变化情况。结果 治疗后24 h,原位肿瘤中,空白对照组SUV_(max)及MR_(FDG)值较治疗前升高(P<0.000 1),联合治疗组SUV_(max)及MR_(FDG)值较治疗前降低(P<0.000 1);远端肿瘤中,空白对照组、PD-1单抗组、单纯放疗组SUV_(max)及MR_(FDG)值较治疗前升高,但仅空白对照组治疗前后SUV_(max)差异有统计学意义(P<0.001),远端肿瘤中MR_(FDG)值上述三组差异均有统计学意义(P<0.01或P<0.000 1)。远端肿瘤联合治疗组SUV_(max)及MR_(FDG)值较治疗前降低(P<0.000 1)。远端肿瘤治疗后比较各组SUV_(max)及MR_(FDG)值,除单纯放疗组和PD-1单抗组外,其余各组间SUV_(max)及MR_(FDG)值差异均有统计学意义(均P<0.05)。免疫组化结果显示,远端肿瘤CD8 T淋巴细胞平均吸光度值高于其他三组(P<0.001);远端肿瘤增殖指数Ki-67免疫组化平均吸光度值低于其他三组(P<0.001)。结论 联合治疗发挥出的协同作用可以降低远端肿瘤生长速度,全身动态^(18)F-FDG PET/CT Patlak多参数显像能够作为PD-1抗体与放射联合治疗远隔效应对小鼠B16F10黑色素瘤的协同作用的监测方法,可为优化联合治疗方案提供可靠的影像学评估参数,对改善肿瘤患者预后具有重要意义。

名中医吴万垠基于“辨病-辨证-辨症”思想治疗老年性肺结节经验

老年肺结节患者是肺癌的高危人群之一。吴万垠教授辨治肺结节以“辨病-辨证-辨症”思想贯穿诊治始终,结合老年患者五脏俱虚、本虚标实特点,辨病以调理“肺-脾-肾”中轴为法,尤其注重固护脾土,辅以解毒抑瘤药物,辨证选用化痰祛瘀药物,并根据症状辅佐宽胸散结、行气止痛、解郁安神等药物,思路周全,临床疗效甚佳。

身体与道德:高校生态人格塑造的离身认知与具身转向

人与自然和谐共生的现代化需要以人格的生态化推进为先导,生态人格是应对中国环境问题的必然选择,也是对人类文明生态转向的积极回应。大学生作为中国式现代化事业的建设者和接班人,理应具备资源节约、环境友好的生态人格。当下高校生态人格塑造存在虚假需要与真实需要、工具理性与价值理性、外部环境与内在秩序、知善能力与行善意向等一系列矛盾,究其原因在于传统生态文明教育的重知观念和离身方式。以具身认知修正离身认知所表现出来的机械唯物主义弊端,需要重视认知主体与场域在认知产生中的作用,打造“心理场”“教育场”“文化场”“实践场”等育人场,织补新时代大学生人格的生态缺失,促进个体人格发展的完满,从而成长为新时代生态型高素质人才。

基于ACBO-GM联合方法的高维变量结构模型修正

工程结构模型修正常面临变量维度高、非线性程度强等现实问题,其模型修正的精度和效率受到严重影响,为改善这一不足,提出基于改进物体碰撞算法(Advanced Colliding Bodies Optimization,ACBO)和高斯白噪声扰动(Gaussian-white-noise Mutation,GM)的联合修正方法。在联合方法中,ACBO实现从传统的“一对一”到“优对多”的碰撞模式的转变,GM则用于保证碰撞过程中种群的多样性,可有效提升结构模型修正效率。基于一系列测试函数,对比分析标准物体碰撞算法(Colliding Bodies Optimization,CBO)和联合优化方法的优化性能;给出基于ACBO-GM联合方法的修正流程,并将其应用于钢框架修正算例和悬臂梁修正实例,对比研究基于联合修正方法与基于遗传算法(Genetic Algorithm,GA)的修正精度和效率。研究表明,ACBO-GM联合优化方法在精度和效率方面都明显优于传统的CBO方法,该优化方法的可行性得到验证;基于ACBO-GM联合方法在钢框架和悬臂梁两个工程结构修正案例中的应用,其修正精度均与基于GA方法的精度一致,但修正效率显著优于基于GA的修正方法。

基于波形指示反演的储层预测方法及应用

由于储层发育的非均质性,单纯根据测井资料刻画出的河道砂体与实际井间砂体的形态符合率较低,砂体连续性及规模都存在不确定性。为了提高储层的预测精度,以大庆长垣南部高台子油田葡一油层组为例,采用基于波形指示反演切片与测井资料结合的方法,优选出了适合研究区的波形指示反演参数,对研究区各小层进行了井震结合沉积微相预测。结果表明,波形指示反演结果具有更好的纵向分辨能力,通过使用优选出的反演参数得到的高精度反演结果,能较好地反映出研究区的储层发育特征。选取与目的层相关性高的波形指示反演方法电阻率反演体,用其反演切片可以预测水下分流河道砂体的连续性和几何形态,具有更高的井间砂体预测精度,能为提高研究区井间储层预测精度提供技术支撑。

基于六维辨证观拆解慢性阻塞性肺疾病辨治体系

六维辨证观是综合多种辨证思维所提出的辨证观念,旨在从病因、病位、病期、病性、病势、病理等6个维度对疾病证态进行系统辨析,有利于临床把握整体,抓住机要。慢性阻塞性肺疾病(COPD)是一种以进行性气流受限和持续的呼吸道症状为特征的呼吸系统疾病,发病多责之于肺气本虚,内外感召或他脏及肺,常有慢性肺系疾病迁延日久或先天不足因素。病位主要在肺,最常波及脾肾,病久可牵连心肝及六腑,是典型的多系统复杂疾病。基本病机是本虚标实,即肺脾肾虚损,痰瘀互结成积,除见气虚气滞、阴阳虚损等病理状态外,还最常见痰饮瘀及微型癥瘕等病理产物。本病分期明确,卫气同病、气分期和气营同病阶段病情寒热之性及邪正之势多变,可因病邪性质、季节地域、体质等因素表现不一,需要谨慎判断和用药;气血同病阶段寒热错杂、虚实并见,治疗棘手,恰是中医药发挥优势的大好时机。