Stability analysis of intermittently jointed rock slopes based on the stepped failure mode

In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.

Seismic stability of jointed rock slopes under obliquely incident earthquake waves

Seismic stability of slopes has been traditionally analyzed with vertically propagated earthquake waves.However,for rock slopes,the earthquake waves might approach the outcrop still with a evidently oblique direction.To investigate the impact of obliquely incident earthquake excitations,the input method for SV and P waves with arbitrary incident angles is conducted,respectively,by adopting the equivalent nodal force method together with a viscous-spring boundary.Then,the input method is introduced within the framework of ABAQUS software and verified by a numerical example.Both SV and P waves input are considered herein for a 2 D jointed rock slope.For the jointed rock mass,the jointed material model in ABAQUS software is employed to simulate its behavior as a continuum.Results of the study show that the earthquake incident angles have significance on the seismic stability of jointed rock slopes.The larger the incident angle,the greater the risk of slope instability.Furthermore,the stability of the jointed rock slopes also is affected by wave types of earthquakes heavily.P waves induce weaker responses and SV waves are shown to be more critical.

Test analysis of stress characteristics on reinforcing rock slope with group anchorage cable

To research the reinforcement effect of a rock slope with group anchorage cablesand the stress characteristics of pre-stressed anchorage cables in the fractured surface,the rock slope calculated model of a wedge block within the double-slide face wasestablished by using the finite difference software according to the actual slope projectcombined with indoor model test.The pre-stress loss rule of the anchorage cable andthe distribution of axial force and the force-transferring mechanism of the anchorage cablewere analyzed during simulation.Also, based on the displacement contour and thesafety factor of the calculated results, the quantitative analysis for the reinforcement effectof the rock slope with group pre-stressed anchorage cable was discovered.The resultscomputed by the software conform with the data in the experiment, which canprove the effectiveness and correctness of parameter selection and model building.

A Reliability Evaluation Method for Intermittent Jointed Rock Slope Based on Evolutionary Support Vector Machine

The randomness of rock joint development is an important factor in the uncertainty of geotechnical engineering stability.In this study,a method is proposed to evaluate the reliability of intermittent jointed rock slope.The least squares support vector machine(LSSVM)evolved by a bacterial foraging optimization algorithm(BFOA)is used to establish a response surface model to express the mapping relationship between the intermittent joint parameters and the slope safety factor.The training samples are obtained from the numerical calculation based on the joint finite element method during this process.Considering the randomness of the intermittent joint parameters in the actual project,each parameter is evaluated at different locations on the site,and its distribution characteristics are counted.According to these statistical results,a large number of parameter combinations are obtained through Monte Carlo sampling.The trained machine learning mapping model is used to obtain the slope safety factor corresponding to each group,and these results are then used to obtain the slope reliability.When the research results were applied to slope disaster treatment along the Yalu River in China’s Jilin Province,it was found that the joint length and joint inclination angle both play key roles in rock slope stability,which should receive more attention in the slope treatment.In summary,this study establishes a method for evaluating the reliability of intermittent jointed rock slope based on an evolutionary SVM model,and its feasibility is verified by engineering application.

Equivalent elastic compliance tensor for rock mass with multiple persistent joint sets:Exact derivation via modified crack tensor

Discontinuities constitute an integral part of rock mass and inherently affect its anisotropic deformation behavior.This work focuses on the equivalent elastic deformation of rock mass with multiple persistent joint sets.A new method based on the space geometric and mechanical properties of the modified crack tensor is proposed,providing an analytical solution for the equivalent elastic compliance tensor of rock mass.A series of experiments validate the capability of the compliance tensor to accurately represent the deformation of rock mass with multiple persistent joint sets,based on conditions set by the basic hypothesis.The spatially varying rules of the equivalent elastic parameters of rock mass with a single joint set are analyzed to reveal the universal law of the stratified rock mass.

Influence of rock property correlation on reliability analysis of rock slope stability: From property characterization to reliability analysis

Cohesion(c) and friction angle(φ) of rock are important parameters required for reliability analysis of rock slope stability. There is correlation between c and φ which affects results of reliability analysis of rock slope stability. However, the characterization of joint probability distribution of c and φ through which their correlation can be estimated requires a large amount of rock property data, which are often not available for most rock engineering projects. As a result, the correlation between c and φ is often ignored or simply assumed during reliability studies, which may lead to bias estimation of failure probability. In probabilistic rock slope stability analysis, the influence of ignoring or simply assuming the correlation of the rock strength parameters(i.e., c and φ) on the reliability of rock slopes has not been fully investigated. In this study, a Bayesian approach is developed to characterize the correlation between c and φ, and an expanded reliability-based design(RBD) approach is developed to assess the influence of correlation between c and φ on reliability of a rock slope. The Bayesian approach characterizes the sitespecific joint probability distribution of c and φ, and quantifies the correlation between c and φ using available limited data pairs of c and φ from a rock project. The expanded RBD approach uses the joint probability distribution of c and φ obtained through the Bayesian approach as inputs, to determine the reliability of a rock slope. The approach gives insight into the propagation of the correlation between c and φ through their joint probability into the reliability analysis, and their influence on the calculated reliability of the rock slope. The approaches may be applied in practice with little additional effort from a conventional analysis. The proposed approaches are illustrated using real c and φ data pairs obtained from laboratory tests of fractured rock at Forsmark, Sweden.

Numerical investigations of rock bridge effect on open pit slope stability

In this study,the effect of rock bridges on rock slope stability was investigated by incorporating nonpersistent joint networks in numerical models,and the critical profiles of an open pit mine were analysed.Parallel deterministic networks of infinite and finite lengths,ubiquitous joint network model and Veneziano joint network model were used in order to simulate the rock fractures.Materials were modelled based on the generalised Hoek-Brown and equivalent Mohr-Coulomb failure criteria.The parallel deterministic infinite and the ubiquitous joint network models produced lower safety factors.The introduction of rock bridges along discontinuity planes in the parallel deterministic network and Veneziano joint network models significantly contributed to the stability and strain distribution,which should be considered in stability analysis of rock mass in open pit by rock slope practitioners.The results show the significance of joints in hard rock behaviour and the joints should be included in order to attain practical and realistic simulations.

Rock slope stability evaluation in static and seismic conditions for left bank of Jinsha River Bridge along Lijiang-Xamgyi'nyilha railway, China

Jinsha River Bridge is located along the Lijiang-Xamgyi＇nyilha railway on the southeastern Tibet plateau; it is an area with a high prevalence of earthquakes. The bridge abutments were designed to be constructed in river bank slopes, where rocks are controlled by two sets of joint planes that significantly influence the stability of the left bank slope. According to the engineering-geological conditions and the characteristics of discontinuities, strength properties of the rock mass were obtained based on Barton model and direct shear test. Numerical analyses were performed using FLAC3D software to examine the slope＇s response to seismic loading. Then in order to evaluate the damage trends of the rock mass under the different loading conditions, a calculation model based on the geological parameters and slope stability was simulated and analyzed using the discrete element numerical simulation program UDEC （Universal Dis- tinct Element Code）, and the effect of degradation of discontinuities on the slope stability was investigated. The results show that the destruction of rock mass under the gravity, bridge foundation, and seismic load are mainly concentrated within 30 m depth of slope, and the slope under loading may slide along joint planes. In addition, the dynamic analysis by amplification of the input loading indicates that instability occurs to the bank slope at a height of about 200 m, and rock blocks will fail under seismic load. Therefore, to prevent the slope from deformation under the engineering loading and strong earthquakes, the bridge foundation should be strengthened.

Developments and Applications of Neutrosophic Theory in Civil Engineering Fields:A Review

Neutrosophic theory can effectively and reasonably express indeterminate,inconsistent,and incomplete information.Since Smarandache proposed the neutrosophic theory in 1998,neutrosophic theory and related research have been developed and applied to many important fields.Indeterminacy and fuzziness are one of the main research issues in the field of civil engineering.Therefore,the neutrosophic theory is very suitable for modeling and applications of civil engineering fields.This review paper mainly describes the recent developments and applications of neutrosophic theory in four important research areas of civil engineering:the neutrosophic decision-making theory and applied methods,the neutrosophic evaluation methods and applications of slope stability,the neutrosophic expressions and analyses of rock joint roughness coefficient,and the neutrosophic structural optimization methods and applications.In terms of these research achievements in the four areas of civil engineering,the neutrosophic theory demonstrates its advantages in dealing with the indeterminate and inconsistent issues in civil engineering and the effectiveness and practicability of existing applied methods.In the future work,the existing research results will be further improved and extended in civil engineering problems.In addition,the neutrosophic theory will also have better application prospects in other fields of civil engineering.

整复手法对骶髂关节错位骨盆及下肢生物力学的影响

目的:观察骶髂关节错位患者在整复手法复位后腰背肌肌张力和对称性,骨盆、下肢生物力学的变化。方法:选取2022年5月至2023年3月期间就诊于福建中医药大学附属第二人民医院的骶髂关节错位患者120例,先理筋手法,再行整复手法,前错位60例,采用屈髋屈膝复位法,后错位60例,采用后伸扳法,隔日治疗1次,共治疗7次。对比治疗前后VAS评分、后表链肌张力K值、后表链肌张力对称值、骨盆倾斜、扭转、水平旋转情况,以及下肢支撑相、摆动相、足偏角的变化。结果:治疗后,骶髂关节前、后错位患者的VAS评分,后表链肌张力系数K值、肌张力对称性差值均较治疗前降低(P<0.05);治疗后,骶髂关节前、后错位患者的骨盆的倾斜、扭转、水平旋转角度均较治疗前减小(P<0.05);治疗后,骶髂关节前、后错位患者的步态周期中的支撑相较治疗前延长(P<0.05),摆动相较治疗前缩短(P<0.05),骶髂关节前错位患者较治疗前足偏角变大(P<0.05),后错位患者足偏角较治疗前变小(P<0.05)。结论:整复手法可以降低骶髂关节错位患者腰背肌肌张力,使两侧腰背肌趋于平衡,且能纠正骨盆的偏歪,改善下肢步态。

李盛华教授运用陇中正骨手法治疗踝关节滑膜嵌顿临证经验撷英

介绍李盛华教授运用陇中正骨手法治疗踝关节滑膜嵌顿的临床经验,对其治疗该病的临床思路及手法进行系统总结。李盛华教授以“顺于自然、手稳法巧、筋骨相通、内外兼治、身心并重”的理论体系为中心治则,运用“拔、揉、摇、落”的正骨手法技巧,达到“筋脉归位,骨正筋柔”的治疗目的。

岩石结构面Grasselli二维粗糙度指标优化及其JRC估算

采用只考虑迎剪侧表观倾角而忽略内部起伏角的Grasselli二维形貌参数θ_(G)来估算结构面粗糙度系数JRC仍有待改进。从θ_(G)的物理意义出发,发现爬坡区内部凸起高度对粗糙度的贡献可表示为其在总爬坡水平距离上的坡角,所有爬坡区提供的坡角之和定义为结构面内部起伏体粗糙贡献,将结构面迎剪侧表观平均倾角θ_(G)和爬坡区内部平均坡角θ_(H)叠加,提出岩石结构面粗糙度新指标θ_(C)。通过获取十条标准JRC剖面线的θ_(C),分析其与JRC之间的关系,建立基于θ_(C)的JRC估算式。计算不同采样间距和不同采样方向下的新指标θ_(C),结果显示θ_(C)具有分形特征且能够反映结构面形貌各向异性。进一步将JRC估算式应用于JRC-JCS模型,通过对比已有研究得到的试验结果以及不同抗剪强度模型的预测效果,验证基于新指标θ_(C)估算的JRC可以准确预测结构面峰值抗剪强度。最后,对二维指标θ_(C)进行三维拓展,提出三维粗糙度新指标(θ_(C))_(3D),并通过结构面形貌各向异性表征验证了其合理性。

基于Ubiquitous-Joint模型的层状岩坡稳定性分析

在应力的作用下,层状岩土体表现出来的力学行为比较复杂,目前广泛使用的各向同性模型不再适用,因此,有必要建立合理描述层状岩质边坡的力学模型。以某公路边坡为工程背景,首先,探讨了层状岩质边坡的失稳机制;然后,利用快速拉格朗日差分法(FLAC3D),建立该边坡的数值分析模型,探讨了强度折减技术在U-biquitous-Joint模型中的实施方法,即对岩体和层理面参数同时进行折减,采用计算不收敛作为边坡临界失稳判据;最后,通过数值计算,分析层状岩质边坡稳定性的影响因素,得到边坡整体安全系数F随节理倾角β先减小后增大,呈现两头高中间低的形态。

面向新能源高渗透系统调峰和调频的系统级储能容量需求分析

高渗透新能源的强不确定性及火电机组占比的逐步减小使得系统灵活性资源不足,系统级储能可高效缓解系统的调峰和调频压力。为此,从系统角度提出了一种面向新能源高渗透系统调峰和调频的系统级储能需求容量确定方法。基于分位数回归分析和高斯混合模型聚类,提出了一种刻画净负荷不确定性的场景集生成方法;基于生成的场景集,建立了一种无储能容量约束的常规火电机组与储能联合优化运行模型,以获取最优运行时储能参与调峰和调频的功率;为了同时兼顾储能利用率和系统运行成本,构建了基于储能电量偏离程度、运行成本增长率指标的储能功率修正模型,并确定储能需求功率和容量,进而分析新能源渗透率、储能功率和容量与满足需求的置信度水平三者之间的关系。算例仿真结果表明,所提方法能够有效确定新能源高渗透系统调峰和调频对储能的需求容量。

基于犹豫模糊混合云模型的航空装备保障系统效能评估

针对航空装备保障系统效能评估过程存在定性指标与定量指标共存、评价信息具有不确定性等问题,提出了一种基于犹豫模糊混合云模型的效能评估方法。根据语言变量的转换与正态云模型之间的混合规则,将犹豫模糊语言术语集转换为梯形云模型,并根据云模型的数字特征,提出了犹豫模糊语言术语集的犹豫度函数与标度函数,实现了对定性指标的量化,兼顾了评价信息的犹豫性、模糊性和随机性。利用区间层次分析法结合灰狼优化算法对效能评估指标体系进行权重赋值,确定系统效能等级。通过应用实例与方法比较表明:犹豫模糊混合云模型不仅评估结果可靠,而且能够识别系统的运行状态,发现系统建设的短板,为提高系统效能提供重要的参考意见,更具有实用性。

基于UKF算法的电动汽车车速坡度估计

精准的车辆车速与道路坡度,是实现车辆驱动防滑控制系统研究的关键,本文考虑到转弯工况,建立转向与道路坡度耦合的混合工况模型,运用UKF算法进行车速坡度联合估计,该算法融合了运动学与动力学两种方式,并且基于MATLAB/Simulink与Carsim搭建联合仿真平台,对所设计的混合工况车速和坡度的估计器与控制策略进行了仿真验证,比传统估计方法精度更高,响应速度以及鲁棒性更好。

Distributed Nash Equilibrium Seeking on Compact Action Sets over Jointly Strongly Connected Switching Networks

This paper studies the distributed Nash equilibrium seeking(DNES)problem for games whose action sets are compact and whose network graph is switching satisfying the jointly strongly connected condition.To keep the actions of all players in their action sets all the time,one has to resort to the projected gradient-based method.Under the assumption that the unique Nash equilibrium is the unique equilibrium of the pseudogradient system,an algorithm is proposed that is able to exponentially find the Nash equilibrium.Further,the authors also consider the distributed Nash equilibrium seeking problem for games whose actions are governed by high-order integrator dynamics and belong to some compact sets.Two examples are used to illustrate the proposed approach.

胫骨平台后倾角变化对单髁关节置换术后关节功能及假体生存率的影响

目的探讨第3代Oxford假体单髁膝关节置换术(unicompartmental knee arthroplasty,UKA)后胫骨平台后倾角(posterior tibial slope,PTS)变化对膝关节功能及假体生存率的影响。方法回顾性分析我院自2017年1月至2021年8月收治的194例(206膝)行内侧单髁膝关节置换术的病人,根据术前及术后后倾角变化差值进行分组:A组60例(63膝),后倾角增大>2°;B组101例(108膝),后倾角变化≤2°;C组33例(35膝),后倾角减小>2°。采用美国特种外科医院(HSS)评分、牛津大学膝关节评分(OKS)及患膝关节屈伸活动度(ROM)评估膝关节功能。统计206膝术后并发症情况并采用Kaplan⁃Meier法评估假体生存率。结果三组术后均获得良好的膝关节功能。术前三组间HSS评分、OKS评分及ROM的差异无统计学意义(P>0.05);末次随访时三组间HSS、OKS评分差异有统计学意义(P<0.05),其中B组HSS评分高于A、C两组,OKS评分低于A、C两组,而三组间ROM差异无统计学意义(P>0.05)。共7例(7膝)出现并发症,其中A组1例,为聚乙烯衬垫脱位;B组3例,分别为内侧胫骨平台塌陷、聚乙烯衬垫脱位、胫骨平台假体松动;C组3例,分别为外侧间室骨性关节炎进展、胫骨平台假体松动、聚乙烯衬垫脱位。三组并发症发生率:C组(8.57%)>B组(2.78%)>A组(1.59%),206膝假体生存率为96.6%。结论对于术后胫骨假体后倾角的选择要个体化、精准化,手术前后胫骨平台后倾角变化≤2°可使病人获得更好的膝关节功能及临床疗效。

节理裂隙发育边坡轮廓成型控制爆破技术

基于夏日哈木镍钴露天矿山边坡轮廓预裂爆破开挖成型施工实践,介绍了圆弧段、破碎段或转角段等节理裂隙发育条件下边坡轮廓成型质量缺陷原因,通过减小预裂孔距、合理控制线装药量、优化装药结构、起爆顺序、延期时间等技术措施,同时对钻孔施工、装药施工等进行过程控制,将边坡轮廓成型整体残留半孔率由不足50%提高到87.5%,有效地控制了节理裂隙发育边坡轮廓成型质量。

中医正骨结合手术治疗踝关节骨折的临床价值分析

目的探讨中医正骨结合手术治疗踝关节骨折的临床效果。方法方便选取2020年4月—2023年2月莆田滨海医院收治的98例踝关节骨折患者作为研究对象,应用随机数表法分为观察组(中医正骨结合手术治疗)和对照组(手术治疗)各49例,对比两组的治疗效果。结果观察组康复优良率(97.96%)高于对照组(81.63%),差异有统计学意义(χ^(2)=7.127,P<0.05)。观察组住院时间、骨折愈合时间短于对照组,差异有统计学意义(P均<0.05)。治疗后,观察组视觉模拟评分低于对照组,生活质量评分高于对照组,差异有统计学意义(P均<0.05)。观察组治疗后的肿瘤坏死因子-α、白细胞介素-6水平以及术后并发症总发生率低于对照组,差异有统计学意义(P均<0.05)。结论在踝关节骨折的临床治疗中,中医正骨结合手术治疗方法有着良好的应用效果。