Instability mechanisms of slope in open-pit coal mines:From physical and numerical modeling

The stability of open-pit mine slopes is crucial for safe and efficient mining operations.However,the presence of weak interlayers poses significant challenges in maintaining the stability of slopes.To explore the impact of the rock arching effect on slopes during excavation,understand the deformation zones and evaluation stages in such environments,and analyze the formation and characteristics of cracks,this study investigated the instability mechanism of open-pit mine slopes with weak interlayers through physical and numerical modeling.Focusing on the Zaharnur open-pit coal mine in China as a prototype,a sophisticated physical model test employing particle image velocimetry and Brillouin optical frequency domain analysis was conducted to comprehensively analyze the displacement and strain variation characteristics of open-pit mine slopes.The displacement,strain,stress redistribution,and failure processes of slopes under excavation were comprehensively analyzed through physical and numerical modeling.The results showed that the slope model exhibited a strain pattern in which the strain incrementally increased from its center toward the edges,and the landslide thrust was converted into an internal force along the arch axis and transmitted to the supports.The concept of the rock arching effect specific to soft rocks was proposed,shedding new light on an important phenomenon specific to open-pit slopes with weak interlayers.Based on its deformation characteristics,the slope could be divided into three areas:The excavation influence area,the crack area and the failure area.In addition,the ratios of the height and width of the outermost cracks to the excavation width fluctuated in the ranges of 0.36–0.49 and0.72–1.00,respectively.These findings contribute to a better understanding of the instability mechanisms in open-pit mine slopes with weak interlayers and provide valuable guidelines for safe mining practices.

Some Problems in Nonlinear Dynamic Instability and Bifurcation Theory for Engineering Structures

In civil engineering, the nonlinear dynamic instability of structures occurs at a bifurcation point or a limit point. The instability at a bifurcation point can be analyzed with the theory of nonlinear dynamics, and that at a limit point can be discussed with the theory of elastoplasticity. In this paper, the nonlinear dynamic instability of structures was treated with mathematical and mechanical theories. The research methods for the problems of structural nonlinear dynamic stability were discussed first, and then the criterion of stability or instability of structures, the method to obtain the bifurcation point and the limit point, and the formulae of the directions of the branch solutions at a bifurcation point were elucidated. These methods can be applied to the problems of nonlinear dynamic instability of structures such as reticulated shells, space grid structures, and so on. Key words nonlinear dynamic instability - engineering structures - non-stationary nonlinear system - bifurcation point - instability at a bifurcation point - limit point MSC 2000 74K25 Project supported by the Science Foundation of Shanghai Municipal Commission of Education (Grant No. 02AK04), the Science Foundation of Shanghai Municipal Commission of Science and Technology (Grant No. 02ZA14034)

Instability energy mechanism of super-large section crossing chambers in deep coal mines

The stress concentration and failure at chamber intersections in coal mine are intense,especially in deepburied,super-large section conditions.In this paper,the plastic radius of super-large section chamber under unequal pressure was corrected on the basis of the size effect.Then,stress and failure evolution of intersections under different crossing angles and equivalent angular bisectors were revealed.Furthermore,2 trajectory curves of failure and stress were analytically expressed,which divided the intersection into 5 influencing zones in the light of stress superposition degree.After determining instability trigger point and instability path,instability energy criterion of intersection can be obtained as K>1,which means that the external energy is greater than the sum of energy consumed by surrounding rock instability and supporting structure failure.Taking coal-gangue separation system of Longgu Coal Mine as example,it was found that there was instability risk under original parameters.For long-term stability,an optimization design method was proposed by considering safety factor,and optimal support scheme was obtained.Field monitoring showed intersections deformations were relatively small with the maximum of 125 mm,which verified the rationality of theoretical analysis.This study provides guidance for the stability control of the intersections under the same or similar conditions.

Monitoring and evaluation of disaster risk caused by linkage failure and instability of residual coal pillar and rock strata in multi-coal seam mining

Comprehensive research methods such as literature research,theoretical analysis,numerical simulations and field monitoring have been used to analyze the disasters and characteristics caused by the linkage failure and instability of the residual coal pillars-rock strata in multi-seam mining.The effective monitoring area and monitoring design method of linkage instability of residual coal pillar-rock strata in multi-seam mining have been identified.The evaluation index and the risk assessment method of disaster risk have been established and the project cases have been applied and validated.The results show that:①The coal pillar will not only cause disaster in singleseam mining,but also more easily cause disaster in multi-seam mining.The instability of coal pillars can cause not only dynamical disasters such as rock falls and mine earthquakes,but also cause surface subsidence and other disasters.②When monitoring the linkage instability of residual coal pillar-rock strata,it is not only necessary to consider the monitoring of the apply load body(key block),the transition body(residual coal pillar)and the carrier body(interlayer rock and working face),but also to strengthen the monitoring of the fracture development height(linkage body).③According to the principles of objectivity,easy access and quantification,combined with investigation,analysis,and production and geological characteristics of this mining area,the main evaluation indexes of the degree of disaster caused by linkage instability of residual coal pillar-rock strata are determined as:microseismic energy,residual coal pillar damage degree,fracture development height.And the evaluation index classification table was also given.④According to the measured value of the evaluation index,the fuzzy comprehensive evaluation method was used to calculate the disaster risk degree in the studied mine belongs to class III,that is,medium risk level.The corresponding pressure relief technology was adopted on site,which achieved a good control effect,and also verified the accuracy and effectiveness of the risk evaluation results.

Failure process and monitoring data of an extra-large landslide at the Nanfen Open-pit Iron Mine

An extra-large landslide occurred on June 19,2021,on the footwall slope of the Nanfen Open-pit Iron Mine in Liaoning Province,China,with a volume of approximately 1.2×107 m3.To elucidate the causative factors,development process,and destructive mechanisms of this catastrophic landslide,comprehensive field tests,investigations,and laboratory experiments were conducted.Initially,the heavily weathered rock mass of the slope was intersected by faults and joint fissures,facilitating rainwater infiltration.Moreover,the landslide contained a substantial clay mineral with highly developed micro-cracks and micro-pores,exhibiting strong water-absorption properties.As moisture content increased,the rock mass underwent softening,resulting in reduced strength.Ultimately,continuous heavy rainfall infiltration amplified the slope's weight,diminishing the weak structural plane's strength,leading to fracture propagation,slip plane penetration,and extensive tensile-shear and uplift failure of the slope.The study highlights poor geological conditions as the decisive factor for this landslide,with continuous heavy rainfall as the triggering factor.Presently,adverse environmental factors persistently affect the landslide,and deformation and failure continue to escalate.Hence,it is imperative to urgently implement integrated measures encompassing slope reinforcement,monitoring,and early-warning to real-time monitor the landslide's deformation and deep mechanical evolution trends.

A simulation study of sampling time point designing for therapeutic drug monitoring based on a population pharmacokinetic model

Aim To develop a method to estimate population pharmacokinetic parameters with the limited sampling time points provided clinically during therapeutic drug monitoring. Methods Various simulations were attempted using a one-compartment open model with the first order absorption to determine PK parameter estimates with different sampling strategies as a validation of the method. The estimated parameters were further verified by comparing to the observed values. Results The samples collected at the single time point close to the non-informative sampling time point designed by this method led to bias and inaccurate parameter estimations. Furthermore, the relationship between the estimated non-informative sampling time points and the values of the parameter was examined. The non-informative sampling time points have been developed under some typical occasions and the results were plotted to show the tendency. As a result, one non-informative time point was demonstrated to be appropriate for clearance and two for both volume of distribution and constant of absorption in the present study. It was found that the estimates of the non-informative sampling time points developed in the method increase with increases of volume of distribution and the decrease of clearance and constant of absorption. Conclusion A rational sampling strategy during therapeutic drug monitoring can be established using the method present in the study.

Precise point positioning and its application in mining deformation monitoring

Precise point positioning (PPP)-based deformation monitoring scheme is presented for the use in mining deformation monitoring. Within the solutions of daily observation, outliers are detected and removed to avoid any potential misinterpretation of the results and then the deformation can be extracted by the coordinate differences between the two consecutive solutions. Meanwhile, because of the special location of a rover station in mining areas, the satellite geometry may be insufficient for a reasonable PPP solution, and the multipath impact an also be significant. Therefore, it is necessary to predict the satellite geometry before any daily observation. To evaluate the ability of extracting the deformation using the PPP-based method, various quality measures were introduced. The results of three datasets of the same station show that the precision of deformation monitored by PPP can reach up to cm level and even mm level.

Slope deformation partitioning and monitoring points optimization based on cluster analysis

The scientific and fair positioning of monitoring locations for surface displacement on slopes is a prerequisite for early warning and forecasting.However,there is no specific provision on how to effectively determine the number and location of monitoring points according to the actual deformation characteristics of the slope.There are still some defects in the layout of monitoring points.To this end,based on displacement data series and spatial location information of surface displacement monitoring points,by combining displacement series correlation and spatial distance influence factors,a spatial deformation correlation calculation model of slope based on clustering analysis was proposed to calculate the correlation between different monitoring points,based on which the deformation area of the slope was divided.The redundant monitoring points in each partition were eliminated based on the partition's outcome,and the overall optimal arrangement of slope monitoring points was then achieved.This method scientifically addresses the issues of slope deformation zoning and data gathering overlap.It not only eliminates human subjectivity from slope deformation zoning but also increases the efficiency and accuracy of slope monitoring.In order to verify the effectiveness of the method,a sand-mudstone interbedded CounterTilt excavation slope in the Chongqing city of China was used as the research object.Twenty-four monitoring points deployed on this slope were monitored for surface displacement for 13 months.The spatial location of the monitoring points was discussed.The results show that the proposed method of slope deformation zoning and the optimized placement of monitoring points are feasible.

Models for Predicting the Jet Trajectory and Intensity Drop Point of Fire Monitors

Two models are defined for predicting the trajectory of a foam jet originating from a fire monitor(hydrant)and the related intensity drop point.An experimental framework is also defined and used accordingly to compare real-time data with the predictions of such models.This mixed theoretical-experimental approach is proven to be effective for the determination of otherwise unknown coefficients which take into account several important factors such as the operation pressure,the elevation angle and the nozzle diameter.It is shown that the mean absolute error is smaller than 20%.

Special Marking of 3D Networks＇ Points for the Monitoring of Modern Constructions

In order to monitor the deformations of modern constructions a local 3D network was usually being established at the surrounding area. The centering error, of both the instrument and targets, causes significant uncertainties in the determination of the x, y, z coordinates of the network＇s points. In order to assure precise centering for both the instrument and targets, not only for the accessible but also for the inaccessible network＇s points, a prototype way of marking is being implied. A special semi-permanent portable metallic stand （Photo 1） was manufactured for marking the accessible points. The stand provides forced instrument centering of the order of_＋0, lmm. It is light enough to carry, it accelerates and facilitates the centering and leveling of the instrument as well as it eliminates the time needed for the measurements. The applied laboratory checks in order to certify the suitability of its use and the provided accuracy are being described. For the inaccessible points special targets were used. The targets were put in permanent attachments （Photos 7-8）, which were also manufactured. Useful conclusions were drawn when these special accessories were used in to a 3D network, which was established for the monitoring of a new football stadium. Two measurement phases were carried out. The first one is with the stadium empty and the second one is when it was crowded （about 32000 people） during a significant football match.

Research on Monitoring Area Division of Quality Grade Changes in County Cultivated Land and Technology of Deploying Monitoring Point

It is an important means in management of improving both the quality and quantity of cultivated land to monitor grade changes in cultivated land quality. How to deploy monitoring network system and its point reasonably and roundly are the key to the technology of monitoring grade changes in cultivated land quality by monitoring grade changes in cultivated land quality dynamically in order to obtain the information to the index of cultivated land quality and its changes based on the existing achievements of farmland classification and grading. Spatial analysis method is used to demarcate monitoring area and deploy monitoring point according to ARCGIS,of which the result can meet the demand for monitoring grade changes in cultivated land.

Distributed fiber optic sensors for tunnel monitoring:A state-of-the-art review

Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.

基于激光点云的铁路隧道特征提取及变形分析

本文以隧道扫描点云为主要研究对象,深入探讨三维激光扫描技术在隧道安全监测中的实际应用,采用理论与实验结合的方法,重点分析了平面拟合、点云配准等理论方法的适应性,针对隧道点云配准、特征提取及变形监测等方面做出重点分析,准确获取隧道内壁点、线、面的变形信息,为隧道特征信息及隧道变形信息准确提取提供技术方案和技术支持。

基于电能质量监测数据的电压暂降敏感负荷识别

为了解决现有方法无法适用于已投运负荷或需要已知敏感负荷类型等问题,提出一种基于电能质量监测数据的敏感负荷识别方法,以有功功率有效值监测数据为切入点,采用Hodrick-Prescott滤波、滑动均值分段进行电压暂降事件时段划分;利用电压暂降事件前、后的电能质量监测数据变化量构建待处理稳态数据集,通过动态聚类来有效划分各次电压暂降事件;对各暂降事件集进行边界拟合,得到多个拟合拐点,并与预设拐点行比较,完成对用户所含敏感负荷的类型识别。通过MATLAB/Simulink仿真算例和实际敏感用户电能质量监测数据对所提方法进行验证,结果表明所提方法可准确识别交流接触器、变频调速系统、可编程逻辑控制器、个人计算机这4种典型敏感负荷,能有效利用稳态电能质量监测数据与电压暂降事件数据进行综合分析,具有成本低、可实施性强的优点。

大米质量检测中的主要技术及控制要点研究

本文分析了当前大米质量检测中的主要技术手段和控制要点。通过对感官检测、物理检测、化学检测3种方法进行详细探讨,认为每种检测技术各有优缺点,且适用场景不同。感官检测较为简便,但主观性强;物理检测精确性较高,但需专业设备;化学检测适合成分分析,但操作复杂。因此,建议在实际应用中根据具体需求选择合适的检测技术,并严格控制检测环境、定期维护检测设备及加强检测人员培训,从而提高大米质量检测的整体水平。

傀儡湖水质监测点位优化研究

为了提升傀儡湖水质监测的准确性与效率,文章对湖泊的地理、气候和水质进行了深入分析,并在八个监测点位进行了为期四个月的氨氮、总磷、总氮采样监测。根据监测结果,只有傀儡湖东南位置的点位可作为参照点,其他点位均有不同程度的污染。傀儡湖的有机污染物主要受气候和周边工业活动的影响,生活排放和湖内养殖也是污染源。通过对各点位进行水质评分,发现除了东南点位外,其他点位的水质均受损,需要优化。优化后的监测点位布局能更准确地反映水质状况,提高数据的代表性和可靠性,有助于指导水质管理,为水环境保护提供支持。

关于大坝监测数据质量评价因子及算法研究

大坝监测数据是判断大坝运行安全的主要依据,为了鉴别数据优劣并选择出可信度较高的数据,文中构建一个大坝监测数据质量评价框架。针对测点之间的相关性、监测项目及仪器的特点,利用Kshape算法找出具有强相关性的测点,再通过相对偏移率、相对平滑率、周期波动程度和精度修正率等评价因子对大坝监测数据进行评价;其次,结合混合蝙蝠算法优化后的长短期记忆网络对大坝监测数据进行分类,构建了大坝监测数据质量评价算法流程。以新疆某大坝监测数据为研究对象进行试验,结果表明所提出的大坝监测数据质量评价算法的准确率为94.33%,可为评价大坝监测数据质量提供有效的解决方法。

Design of pharmacodynamic monitoring system based on acupuncture differential thermometry

To control drug effects by detecting temperature difference between biologically active point（BAP）and intact area of skin for treatment of mental illness,a device is developed for monitoring the temperature of BAP and the dose medication and its change in real time to increase effectiveness of treatment.Two electrodes by Foll R method are used and BAP is determined based on topographic anatomical reference points.The temperature values are measured by integral thermometers DS18B20.the received data are processed and temperature difference is calculated and displayed under the control of microcontroller Atmega32.The obtained data confirm the correlation between the temperature difference indicators BAP C7,Gi4 and neurological scales assessing severity of mental illness.The experimetal results show that the temperature difference can be criteria for evaluating the effects of drugs,which is the basis for computer control systems of of medical process of mental patients.

IBIS-FM radar as a tool for monitoring hill slopes during excavations in hydropower projects:A case study from Bhutan Himalayas

Excavation is common in the construction of hydropower projects.Monitoring for both stable and unstable slopes is a pressing requirement during progressive excavations with or without cut-slope support measures.The present study is about an excavation carried out in a proposed concrete gravity dam site on the right bank slope of the Punatsangchhu River in western Bhutan.During the excavation,the right bank abutment witnessed multiple events of slope failures of various magnitudes.One major landslide occurred on 23 July 2013 in the toe of the right abutment,where foliation/multiple sheared/fractured zones/seams in quartz-feldspathic biotite gneiss dip towards the valley.During further excavations/piling works,a subsequent landslide on the downstream,within the body of the July 2013 landslide,occurred on 12 August 2016.As a result,a real-time monitoring of the slope became necessary to facilitate further excavations for achieving the dam foundation.Thus,the advanced slope monitoring instrument like Image By Interferometric Survey e Frequency Modulated(IBIS-FM)radar was deployed for monitoring the right bank slope during the excavation for the construction of~129 m high dam.The displacement of the hill slope is assessed based on this system by monitoring point locations as well as areas by assigning different threshold values for providing timely alerts.This real-time monitoring was effective in identifying the reactivation of August 2016 landslide that occurred on 22 January 2019.Thus,this study showcases the efficiency of IBIS-FM radar in monitoring slope instability with sub-millimeter accuracy on a near real-time basis.

轨道交通保护监测的自动化监测技术分析

在城市基础设施不断完善的背景下,轨道交通建设项目数量持续增加,在为人们日常交通带来很大便利的同时,也促进了城市高速发展。然而,在轨道交通运输过程中,会受到各种潜在因素的影响,存在很多质量与安全隐患,需要进行动态化与实时性的监测,及时发现和解决问题,有效规避各类风险。本文重点研究了轨道交通保护监测的自动化监测技术运用要点,旨在提高轨道交通保护监测工作精度,减少人力与物力的过多投入,为企业创造出更多效益。