Upper-Bound Limit Analysis of the Multi-Layer Slope Stability and Failure Mode Based on Generalized Horizontal Slice Method

Multi-layer slopes are widely found in clay residue receiving fields.A generalized horizontal slice method(GHSM)for assessing the stability of multi-layer slopes that considers the energy dissipation between adjacent horizontal slices is presented.In view of the upper-bound limit analysis theory,the energy equation is derived and the ultimate failure mode is generated by comparing the sliding surface passing through the slope toe(mode A)with that below(mode B).In addition,the influence of the number of slices on the stability coefficients in the GHSM is studied and the stable value is obtained.Compared to the original method(Chen’s method),the GHSM can acquire more precise results,which takes into account the energy dissipation in the inner sliding soil mass.Moreover,the GHSM,limit equilibrium method(LEM)and numerical simulation method(NSM)are applied to analyze the stability of a multi-layer slope with different slope angles and the results of the safety factor and failure mode are very close in each case.The ultimate failure modes are shown to be mode B when the slope angle is not more than 28°.It illustrates that the determination of the ultimate sliding surface requires comparison of multiple failure modes,not only mode A.

Improved Statically Solvable Slice Method for Slope Stability Analysis

Although slice methods are simple and effective slope stability analysis approaches,they are statically indeterminate.Several modifications of the slice method,such as the Spencer,MorgensternPrice,and Chen-Morgenstern methods,are statically determinate and solvable as they assume the inter-slice force inclination angle;however,there is a small gap between the assumptions and actual landslide stability analysis.Through reasonable theoretical analysis,the Su slice method provides a reliable approach for determining the inter-slice force inclination angle that can be used in slice analysis to accurately analyse,calculate,and evaluate the stability of landslides.However,the Su slice method requires further research and analysis,especially in terms of the parameter values sinλbiandρ.In this study,we investigated more accurate methods for calculating the parameters sinλbiandρ.In addition,an adjustment coefficient(μ)was introduced to improve the solution method for the inter-slice force inclination angle.The inter-slice force inclination and safety factors of three landslides with arc-shaped slip surfaces and one landslide with a polyline-shaped slip surface were analysed and compared using the different slice methods.The improved inter-slice force inclination not only satisfies the calculation of static force equilibrium condition but also satisfies the calculation of both the force and moment equilibrium conditions.The improved method for calculating inter-slice force inclination presented the best correlation.The safety factors calculated using the improved Su slice method were close to those obtained using numerical simulations and the Morgenstern-Price method.Despite negligible differences among the safety factors calculated using the Su slice,improved Su slice,and M-P methods,the accuracy of the improved Su slice method was better than the M-P method in terms of inter-slice force inclination angles which can be useful to improve protection engineering design.

Time Slice Analysis Method Based on OTCA Used in fMRI Weak Signal Function Extraction

The original temporal clustering analysis (OTCA) is an effective technique for obtaining brain activation maps when the timing and location of the activation are completely unknown, but its deficiency of sensitivity is exposed in processing brain activation signal which is relatively weak. The time slice analysis method based on OTCA is proposed considering the weakness of the functional magnetic resonance imaging (fMRI) signal of the rat model. By dividing the stimulation period into several time slices and analyzing each slice to detect the activated pixels respectively after the background removal, the sensitivity is significantly improved. The inhibitory response in the hypothalamus after glucose loading is detected successfully with this method in the experiment on rat. Combined with the OTCA method, the time slice analysis method based on OTCA is effective on detecting when, where and which type of response will happen after stimulation, even if the fMRI signal is weak.

Rock bridge slice element method in slope stability analysis based on multi-scale geological structure mapping

The searching method of failure surface which consists of complex geological structures in high and steep rock slopes was studied. Based on computer simulation technology and Monte-Carlo method, three dimensional multi-scale geological structures such as engineering scale and statistical scale structures of the slope were simulated. The searching method of failure route which consists of joints and rock bridges was determined via simulation annealing method by considering the shear strength of joints or rock bridges in one supposed route. When shear strengths of all the supposed routes were computed, the least shear strength route was considered failure route. Then, the inclined slice of joint slices and rock bridge slices were separated according to the position of joints and rock bridges. For the rock bridge slices, by distinguishing the failure model, the force direction to the next slice was defined. Finally, the limit equilibrium equations for every slice were established, and the slope stability factor was obtained. One practical example indicates that the discussed method is more closely to the real condition.

充水作用下露天煤矿内排土场边坡稳定性分析

为分析废弃矿坑改造成蓄水湖时充水高度对内排土场边坡稳定性的影响,采用室内相似试验、数值模拟和理论分析的方法对不同水位高度下内排土场边坡稳定性进行研究。研究结果表明:随着充水高度的增加,浸润线运移速度、边坡最大位移、孔隙水压力和边坡土体受到的压力整体呈增长趋势。充水高度越大,边坡倾角越大,边坡稳定系数越低。研究结论为露天煤矿改造成蓄水湖或蓄能水电站项目工程提供参考。

Stability analysis of tunnel face reinforced with face bolts

Face bolting has been widely utilized to enhance the stability of tunnel face,particularly in soft soil tunnels.However,the influence of bolt reinforcement and its layout on tunnel face stability has not been systematically studied.Based on the theory of linear elastic mechanics,this study delved into the specific mechanisms of bolt reinforcement on the tunnel face in both horizontal and vertical dimensions.It also identified the primary failure types of bolts.Additionally,a design approach for tunnel face bolts that incorporates spatial layout was established using the limit equilibrium method to enhance the conventional wedge-prism model.The proposed model was subsequently validated through various means,and the specific influence of relevant bolt design parameters on tunnel face stability was analyzed.Furthermore,design principles for tunnel face bolts under different geological conditions were presented.The findings indicate that bolt failure can be categorized into three stages:tensile failure,pullout failure,and comprehensive failure.Increasing cohesion,internal friction angle,bolt density,and overlap length can effectively enhance tunnel face stability.Due to significant variations in stratum conditions,tailored design approaches based on specific failure stages are necessary for bolt design.

不同干燥方式对柠檬片品质的影响

该研究旨在探究不同干燥方式对贮藏期柠檬片品质的影响。分别采用真空冷冻干燥(vacuum freeze drying,VFD)、热风干燥(hot air drying,HAD)、微波干燥(microwave drying,MD)3种方式加工制备柠檬片,并研究了3种干燥方式对柠檬片色泽、基础品质、营养物质和风味的影响。结果表明,柠檬片经过真空冷冻干燥、热风干燥、微波干燥不同干燥处理后品质与风味不同。冻干组柠檬片具有较小的收缩率(11.65%),较高的复水比(5.14)、亮度值(48.6)和V_(C)含量(3.13 mg/g DW),电子鼻各传感器的响应值较高,即其色泽、品质、风味都优于热风干燥与微波干燥方式。因此,使用冻干工艺可以保证品质。

Time-Varying Mesh Stiffness Calculation and Dynamic Modeling of Spiral Bevel Gear with Spalling Defects

Time-varying mesh stiffness(TVMS)is a vital internal excitation source for the spiral bevel gear(SBG)transmission system.Spalling defect often causes decrease in gear mesh stiffness and changes the dynamic characteristics of the gear system,which further increases noise and vibration.This paper aims to calculate the TVMS and establish dynamic model of SBG with spalling defect.In this study,a novel analytical model based on slice method is proposed to calculate the TVMS of SBG considering spalling defect.Subsequently,the influence of spalling defect on the TVMS is studied through a numerical simulation,and the proposed analytical model is verified by a finite element model.Besides,an 8-degrees-of-freedom dynamic model is established for SBG transmission system.Incorporating the spalling defect into TVMS,the dynamic responses of spalled SBG are analyzed.The numerical results indicate that spalling defect would cause periodic impact in time domain.Finally,an experiment is designed to verify the proposed dynamic model.The experimental results show that the spalling defect makes the response characterized by periodic impact with the rotating frequency of spalled pinion.

不同教学指导方式对组织学实验教学效果的影响

目的:探讨线上、线下两种教学方式对组织学实验教学效果的影响.方法:选取本校2020、2021级263名护理专业的学生作为研究对象,按所在年级分为线下班(n=129,2021级学生,采用线下指导方式)和线上班(n=134,2022级学生,采用线上指导方式),比较两组学生出勤、实验报告、实验操作、切片考试及总评5类成绩.使用Pearson直线相关分析计算各类成绩间的相关系数.纳入性别、年龄、教学方式等因素分别对五类成绩构建多因素线性回归方程.结果:线下班的实验报告、切片考试、总评成绩高于线上班,差异有统计学意义(P<0.05).切片考试与总评成绩的相关系数接近1.控制性别、年龄两个因素后,教学方式对实验报告、实验操作、切片考试及总评4类成绩有显著影响,差异有统计学意义(P<0.05).结论:利用网络资源开展组织学实验教学,线下指导方式有利于提高护理专业学生的成绩.

3D打印技术在舰船管系三维建模设计中的应用

为提升复杂结构舰船管系的设计灵活性,研究3D打印技术在舰船管系三维建模设计中的应用。利用CAD软件建立舰船管系的二维模型,依据舰船管系三角面片的交线段,确定舰船管系的点、线、面关系,将其转换为舰船管系三维模型。将舰船管系三维模型,导入切片软件中,利用切片引擎运行3D打印切片引擎增强处理算法,切片处理舰船管系三维模型,输出舰船管系三维模型的Gcode代码文件。将Gcode代码导入3D打印机,采用Z字填充法填充舰船管系3D打印材料,实现舰船管系模型的3D打印。实验结果表明,该方法可以精准打印舰船管系三维模型,打印结果的尺寸偏差小,提升了舰船管系设计的灵活性。

基于四段指标评估法的卢文·菲鲁斯削球打法技战术分析

运用四段指标评估法深度剖析德国乒乓球男子削球运动员卢文·菲鲁斯(Ruwen Filus)五场比赛的技战术,研究外协会男子运动员削球打法特点,丰富国内削球打法。文章采用了文献资料法、录像观察法、数理统计法进行分析。研究发现,卢文·菲鲁斯在发抢段的使用率和得分率最为突出;在接抢段使用率较低,但得分率较高;在相持I段,使用率和得分率均较好;在相持II段的发抢率是最高的。综合分析卢文·菲鲁斯抢攻能力突出,值得国内削球运动员借鉴,具有重要参考价值。

基于改进条分法的滑坡稳定性分析

为了研究边坡渐进破坏过程及稳定性演化规律,在传统条分法基础上引入两种土体本构模型,将变形与受力结合建立新型条分法,并提出一种新型边坡稳定性分析方法,从滑面点、滑面和滑体进行多维度描述,有效地展现滑坡渐进破坏过程。对卡子湾滑坡进行实例分析,结果表明:用传统稳定性方法计算的稳定系数为1.0659,即滑坡为欠稳定状态,结合滑坡的点面体评价指标分析,滑坡在临界状态前移过程中,条分法计算的第29条块出现突变,证明滑坡在临界状态点移动至第29条块后可能会突然发生整体破坏,并且将理想弹塑性模型与剪应力模型的计算结果进行对比分析,得到基于剪应力本构模型的条分法更加接近滑坡受力情况,此类方法可以为滑坡的监测预警提供参考。

边坡稳定性整体分析法中滑面正应力分布研究

边坡稳定性的整体分析法是严格极限平衡法,无严格条分法的不收敛问题,还能实现三维严格极限平衡法。但整体分析法一直居于非主流地位,原因可能是整体分析法无法像Morgenstern-Price法那样产生静力许可力系。针对二维问题,分析了造成这一问题的原因——滑面正应力构造不当,并建议采用双参数滑面应力修正的折线方式和Fourier方式,这2种方式都能满足滑面正应力分布的自然分解和端点条件。对典型边坡案例的分析表明,在产生静力许可力系的能力方面,整体分析法远优于以Morgenstern-Price法为代表的经典条分法。因此建议在边坡稳定性分析中优先采用整体分析法。

软土地基沟渠开挖诱发远处围堰失稳的实例分析

以福建滨海软土地基上因地基处理需要修建的临时围堰局部失稳垮塌的工程为例,通过围堰破坏段与远处沟渠施工段的时间、空间对应关系,推断远处沟渠开挖是造成围堰失稳的主要因素。然而围堰与沟渠间隔相对较远,且沟渠开挖规模较小,两者间的相互影响在施工期间没有得到关注。为了验证事故原因,分别采用考虑偏心荷载的条形基础圆弧滑动解析解、极限平衡条分法和数值分析法计算了沟渠开挖前后的最危险滑动面安全系数,同时分析了沟渠开挖对总位移场的影响。结果显示:3种方法在最危险滑动面安全系数计算结果上具有一致性。沟渠开挖对围堰整体稳定性有显著影响,沟渠开挖后位移场出现贯通,最危险滑动面呈现圆弧+长直线组合滑动形态。由于上覆土无法有效发挥抗滑作用力,安全系数明显小于常规圆弧滑动面。结果表明:尽管围堰与沟渠间的净距达20 m,净距与围堰平均宽度比达3.3倍,但从围堰失稳的现场特点和计算分析两方面,均证实远处沟渠开挖是造成围堰失稳的根本原因。本案例围堰失稳垮塌值得软土地区工程界重视。

基于层一致性平均教师模型的半监督岩石薄片图像分类

传统的岩石薄片图像分类依赖于大量人工标记的图像样本,这种方式受制于标记人员的经验和能力,且无法通过不断增加的未标记岩石薄片图像样本实现分类能力的可扩展式增强。该文提出的在平均教师(mean teacher, MT)模型的基础上,通过在无监督损失中添加层一致性正则化项的方式约束师生模型的层次结构,实现对未标记数据信息的有效利用。消融实验和层一致性平均教师(hierarchy consistency mean teacher, HCMT)模型对比实验结果表明,层一致性正则化方法利用了未标记数据的有效信息,提升了MT模型的分类效果,使得HCMT模型可以在半标记数据集中获得如全标记数据集相似的分类能力。该实验表明,半监督学习模型利用大量未标记岩石薄片图像数据可以提升模型分类的能力。

碎石桩加固软土地基条形基础的承载力

为了快速得出碎石桩加固软土地基条形基础的极限承载力,基于Morgenstern-Price切片法建立了碎石桩改良软粘土承载力的分析模型,以此进行参数研究,并进行Gauss和线性拟合。研究结果表明所建立的分析模型取得了较好的结果,当间距/直径比(S/D)等于1.4时可以取得最好的改良效果,改良率(IR)随着置换率的增加而显著增加,并且参数与改良率(IR)的拟合结果具有较高的精度,为碎石桩加固软土地基条形基础的应用提供科学依据。

荧光染色法与KOH湿片法在皮肤真菌直接镜检检查中的应用价值

目的对比荧光染色法与氢氧化钾(KOH)湿片法用于皮肤真菌直接镜检检查中的效果。方法以2022年10月至2023年10月我院接诊疑似皮肤真菌感染患者90例作为研究对象,采集皮损样本,分别通过荧光染色法、KOH湿片法进行镜检检查,以临床综合诊断结果为金标准,对比两种检查方法的阳性检出率。结果临床综合诊断结果显示,31例患者确诊为手足癣,占比34.44%;19例患者确诊为体股癣,占比21.11%;11例患者确诊为头面癣,占比12.22%;20例患者确诊为甲癣,占比22.22%。荧光染色法直接镜检取得的总阳性率高于KOH湿片法(P<0.05)。结论通过荧光染色法进行皮肤真菌直接镜检检查相比KOH湿片法结果更准确,且操作更为便捷、快速。

测试片法在食品菌落总数检测中的应用可行性分析

为评估测试片法在食品菌落总数检测中的应用可行性及与传统的平板计数法的一致性,选取大肠埃希氏菌、枯草芽孢杆菌和蜡样芽孢杆菌作为标准菌株,同时采集生肉、水产品、乳制品、面食和果蔬等自然污染样品,分别采用测试片法和平板计数法对上述样品进行菌落总数检测,并采用t检验分析两种方法测定结果的一致性。结果表明,两种方法对标准菌株的检测结果无显著差异(P>0.05),对自然污染样品的检测也无显著差异(P>0.05),其中现制面条菌落总数最多,牛肉菌落总数最少。这表明测试片法与平板计数法的检测结果具有很好的一致性。测试片法操作简便,为食品菌落总数快速检测提供了可行的技术手段,具有一定的应用前景。

深切峡谷陡坡段倒虹吸施工对边坡稳定性影响

九道河倒虹吸位于云南省楚雄市禄丰县境内西河峡谷,谷峰相对高差280 m~360 m,河谷呈“V”形,是典型的深切峡谷。以九道河倒虹吸工程为背景,针对深切峡谷陡坡施工期间边坡安全稳定性分析,采用GeoStudio软件中的SLOPE/W模块建立边坡模型,主要分析边坡段倒虹吸镇墩采用不同的施作顺序对边坡安全稳定性的影响。根据不同施作顺序边坡安全稳定性的变化情况,寻找更为合理的施作顺序,分析结果对同类型工程的施工有着实际的指导意义。

Simplified method for analyzing soil slope deformation under cyclic loading

Reasonable assessment of slope deformation under cyclic loading is of great significance for securing the safety of slopes. The observations of centrifuge model tests are analyzed on the slope deformation behavior under cyclic loading conditions. The potential slip surface is the key for slope failure and follows two rules:(i) the relative horizontal displacement along the potential slip surface is invariable at an elevation, and(ii) the soil along the slip surface exhibits the same degradation pattern. These rules are effective regardless of the location of the potential slip surface throughout the entire deformation process of a homogeneous slope, ranging from the initial deformation stage to the failure process and to the post-failure stage. A new, simplified method is proposed by deriving the displacement compatibility equation and unified degradation equation according to the fundamental rules. The method has few parameters that can be determined through traditional element tests. The predictions from the proposed method agree with the centrifuge test results with vertical loading and shaking table loading. This result confirms that the proposed method is effective in predicting the full deformation process of slopes under different cyclic loading conditions.