Investigation of rockfall-prone road cut slope near Lengpui Airport,Mizoram, India

Rockfall is one of severe natural hazards that are frequently reported in northeast region of India. It carries rock block falling from the cliff with high velocities and energies which can result in damages to vehicles, disruption to transportation, injuries and fatalities. The massive rockfall event which occurred in April 2017 on the highway NH-44A, near Lengpui Airport, blocked the traffic for 1 d, and fortunately, no casualties were reported as the event occurred in the night. This is the only highway connecting the Aizawl city to the airport and the region is highly prone to rockfall events. Hence assessment of rockfall along this highway is necessary. In the current study, rockfall hazard assessment has been carried out on three locations by rockfall hazard rating system (RHRS). During pre-failure analysis, the result shows that most hazardous slopes have RHRS score of 639. The slopes were found to be vulnerable and later on the rockfall activity occurred. Three-dimensional (3D) stability analysis has been carried out using 3DEC software package to analyze the failure behavior and to decide the rockfall-prone zone (unstable blocks) for slope. The total displacement of 2.24 cm and velocity of 2.25 mm/s of the failed block have been observed in the numerical analysis. Further, the rockfall vulnerable zone (unstable blocks) is considered to determine the parameters such as run-out distance, bounce height and energies of the falling rock blocks. The maximum total kinetic energy of 5047 kJ has been observed in the numerical analysis with the maximum run-out distance up to 18 m.     

Slope mass rating and kinematic analysis of slopes along the national highway-58 near Jonk,Rishikesh, India

The road network in the Himalayan terrain, connecting remote areas either in the valleys or on the hill slopes, plays a pivotal role in socio-economic development of India. The planning, development and even maintenance of road and rail networks in such precarious terrains are always a challenging task because of complexities posed by topography, geological structures, varied lithology and neotectonics. Increasing population and construction of roads have led to destabilisation of slopes, thus leading to mass wasting and movement, further aggravation due to recent events of cloud bursts and unprecedented flash floods.Vulnerability analysis of slopes is an important component for the Landslide Hazard Assessment andSlope Mass Characterisation guide planners to predict and choose suitable ways for construction of roads and other engineering structures. The problem of landslides along the national highway-58(NH-58) from Rishikesh to Devprayag is a common scene. The slopes along the NH-58 between Jonk and Rishikesh were investigated, which experienced very heavy traffic especially from March to August due to pilgrimage to Kedarnath shrine. On the basis of slope mass rating(SMR) investigation, the area falls in stable class, and landslide susceptibility score(LSS) values also indicate that the slopes under investigation fall in low to moderate vulnerability to landslide. More attentions should be paid to the slopes to achieve greater safe and economic benefits along the highway.     

A modified Sarma method for stability analysis of layered slopes

Bulletin of Engineering Geology and the Environment - A large number of layered slopes with complex lithological units and complex sliding surfaces exist in nature. The conventional Sarma method,...     

Engineering properties and slope stability of road cuttings along the enugu-onitsha express road,Southeastern Nigeria

The new express highway linking Enugu (in Enugu State) and Onitsha (in Anambra State) both in Southeastern Nigeria, is plagued with landslides, a few years after completion. The active landslides are concentrated on the road cuttings between Otuocha junction and Awka, specifically between km 29 and km 40 from the Onitsha end of the road. Three of these slides have been studied. The investigation involved detailed field and laboratory studies of the physical conditions and geotechnical properties of the sites and soils therein. The laboratory tests performed included grainsize distribution analysis, Atterberg limits, specific gravity, natural water content, bulk density, permeability and shear strength. Each site was analysed for stability using the strength parameters obtained from laboratory tests and Bishop's 1955 simplified method of analysis. There is evidence from the analyses results that although the cut slopes are vulnerable to toe undermining and over-steepening by runoff, the generally “loose” nature of the soils as evidenced by the low bulk density (1580–1960 kg/cm³), fairly high void ratio (0.53–0.66) but low permeability (2.15–3.25×10^?3 cm/s) and consequent high saturation and strength reduction during the rains, are the major contributors to instability of the cut slopes.     

高速公路高边坡稳定性的联合监测分析

介绍了多点位移计和锚索测力计在安徽省某高速公路高边坡稳定性监测中的联合应用,实时监控坡体变形过程。采用比较法、作图法、特征值统计法和测值影响因素分析法等,以边坡变形和破坏现象为依据,结合现场施工和地质情况,将两种仪器的监测成果进行综合分析,探讨了各测点位移与空间、时间的关系,对比了位移与锚固力随时间的变化规律,分析了边坡变形发展的阶段及其主要影响因素,动态分析了该边坡的稳定性,提供了利用联合监测的方法全程跟踪和指导现场实现信息化施工的例证。     

A simplified approach for stability analysis of slopes reinforced with one row of embedded stabilizing piles

Embedded stabilizing piles are new anti-slide structures that are unlike traditional stabilizing piles. The pile heads are embedded at a certain depth below the surface of a slope. The piles do not need to support the thrust of the entire upslope sliding mass, and it is, therefore, possible to reduce the sliding thrust on the piles. The embedded depth of the pile heads is an important parameter to maximize the anti-sliding function. Based on an analysis of the stability mechanism of a reinforced landslide with one row of embedded stabilizing piles, a calculation method for the embedded depth of a pile head using limit equilibrium theory is proposed. The related calculation formula is derived in detail using the transfer coefficient method. The proposed method features a close correlation between the embedded depth of a pile head and the design factor of safety of a slope to be reinforced. Additionally, the method can quantitatively demonstrate the relationship that the factor of safety of the slope for the failure mode of the surpassing pile head decreases as the embedded depth of the pile head increases. For a given factor of safety, the range of the maximum bending moment, the maximum shear force on a pile and the lateral displacement at the pile head also can be approximately predicted. Several calculation examples that are closely related to practical engineering applications are examined to show the convenience and rationality of the proposed method. In addition, the theoretical analysis is compared with the results of the numerical simulation of an actual accumulation landslide control engineering project. The results further demonstrate that the proposed theoretical analysis method is reasonable and applicable.     

公路隧道洞口滑坡稳定性分析与治理方案研究

介绍了某公路隧道洞口滑坡的工程地质条件及特征,对其进行稳定性分析与评价,综合考虑滑坡形态及施工进度的要求,提出采取削方减载的方式对隧道洞口影响范围内的滑坡进行治理,有效保障隧道施工与运行安全。     

Dynamic stability analysis of jointed rock slopes using the DDA method: King Herod's Palace, Masada, Israel

A dynamic, two-dimensional, stability analysis of a highly discontinuous rock slope is demonstrated in this paper. The studied rock slope is the upper terrace of King Herod's Palace in Masada, situated on the western margins of the seismically active Dead Sea Rift. The slope consists of sub-horizontally bedded and sub-vertically jointed, stiff, dolomite blocks. The dynamic deformation of the slope is calculated using a fully dynamic version of DDA in which time-dependent acceleration is used as input.The analytically determined failure modes of critical keyblocks in the jointed rock slope are clearly predicted by DDA at the end of the dynamic calculation. It is found however that for realistic displacement estimates some amount of energy dissipation must be introduced into the otherwise fully elastic, un-damped, DDA formulation. Comparison of predicted damage with actual slope performance over a historic time span of 2000 years allows us to conclude that introduction of 2% kinetic damping should suffice for realistic damage predictions. This conclusion is in agreement with recent results of Tsesarsky et al. (In: Y.H. Hatzor (Ed.), Stability of Rock Structures: Proceedings of the Fifth International Conference of Analysis of Discontinuous Deformation, Balkema Publishers, Lisse, 2002, pp. 195–203) who compared displacements of a single block on an inclined plane subjected to dynamic loading obtained by DDA and by shaking table experiments.Using dynamic DDA it is shown that introduction of a simple rock bolting pattern completely stabilizes the slope.     

Analysis of landslide stability under seismic action and subsequent rainfall: a case study on the Ganjiazhai giant landslide along the Zhaotong-Qiaojia road during the 2014 Ludian earthquake,Yunnan, China

In a strong earthquake, not only a large number of coseismic landslides are triggered, but relaxation and cracks in the rocks and soils are induced, which make these rocks and soils vulnerable to instability during subsequent rainfall; thus, strong earthquakes always have long-term effects on landslides. The geo-hazards along the Zhaotong-Qiaojia road in the 2014 Ludian earthquake (Ms 6.5) of Yunnan Province, China, were investigated, and the Ganjiazhai giant landslide was chosen as a case study. First, using the limit equilibrium analysis and Newmark method, the critical seismic intensity of the landslide before the earthquake was evaluated. Secondly, the dynamic failure process of the landslide under the measured ground motion was simulated with the discontinuous deformation analysis method. Lastly, based on stress–seepage coupling analysis and precipitation data from Ludian meteorological station, the stability of the landslide during subsequent rainfall after the earthquake was predicted. The results show that the critical seismic intensity was within degrees VIII–IX, which is consistent with the results of the earthquake damage investigation. The dynamic failure process can be divided into four stages, and four scarps formed; the potential sliding zones during the subsequent rainfall were at the first scarp and the fourth scarp, and their critical rainfall amounts were 35–40 mm and 55–60 mm, respectively. In this paper, failure process simulation and stability prediction of the landslide before, during, and after the strong earthquake are presented, which provide analysis methods for the dynamic stability of landslides in the meizoseismal area.

     

边坡稳定分析条分法的一个全局优化算法

根据毕肖普法和非线性规划原理 ,对工程实践中最为广泛应用的圆弧滑裂面法 ,提出了一个较为完整的优化数值模型 ,并运用障碍函数法求解了该优化数值模型。为避免陷入“局部优化点” ,运用随机投点法建立了一种全局优化算法。通过工程实例分析 ,计算结果是令人满意的     

A non-asymptotic model for the stability analysis of thin biperiodic cylindrical shells

The object of considerations is a thin linear-elastic cylindrical shell with arbitrary cross-section having a periodic structure in both directions tangent to the shell midsurface. The aim of this paper is to propose a new averaged non-asymptotic model of dynamical stability problems for such shells. As a tool of modeling we shall apply the tolerance averaging technique, given for periodic structures in Woźniak and Wierzbicki [Averaging techniques in thermomechanics of composite solids, Wydawnictwo Politechniki Częstochowskiej, 2000]. In contrast with models obtained by means of asymptotic homogenization methods, the proposed one makes it possible to describe the effect of the period lengths on the global shell stability, called a length-scale effect.     

A critical analysis of recent advances in the techniques for the evaluation of renewable energy projects

Renewable energy investment is an integral part of sustainable economic development agenda. Whereas some important advances have been made in recent years to assist project investors in making better use of financial risk management instruments and taking into consideration real options embedded in renewable energy projects, this research asserts that, owing to failure to consider both behavioural uncertainty and the limit of risk transfer, these approaches may still lead to a biased evaluation result. Drawing on a novel concept of “risk-bearing capacity”, the research suggests developing a new approach whereby investors can incorporate the choice of financial protection measures into investment evaluation in a coherent way.     

A hybrid approach for the analysis and prediction of elevator passenger flow in an office building

In an Elevator Group Control System (EGCS), the analysis and prediction of elevator traffic can improve service quality and system performance. For this purpose, we propose a new hybrid approach to analyze and predict elevator passenger flow. In this approach, nonlinear analysis methods are used to reveal the internal dynamic characteristics of passenger flow time series collected from an office building. The results suggest that passenger flow has obvious fractal and chaos characteristics. Based on these characteristics, the support vector machine (SVM) method and fuzzy information granulation (FIG) method are employed to predict passenger flow. The simulation results suggest that the accuracy of passenger flow prediction can meet the identification requirements of elevator traffic patterns in an EGCS. Therefore, the proposed approach can effectively address the passenger flow analysis and prediction problems of office buildings and the results can be used as a foundation for practical application in an EGCS.     

Analyzing the stability of a failing rock slope for suggesting suitable mitigation measure: a case study from the Theng rockslide,Sikkim Himalayas,India

At km 87.20 near Theng on the North Sikkim Highway, India, severe rock falls and slides in recent years rendered 180 m stretch of this important road corridor in the Sikkim Himalayas risky and vulnerable to the commuters. The rockslide at Theng has, thus, been studied in detail at 24 discrete locations using the ground-based topographic, lithologic and structural data with an objective to evaluate the mechanisms of rock sliding for suggesting the most effective mitigation measure. In this study, large scale geological mapping and site-specific kinematic analyses in different spatial domains corroborated that within this 180 m stretch, despite having a competent lithology (quartzo feldspathic gneiss and quartzites), the possibility of both plane and wedge failures are high because of gentler and unfavourably oriented planar discontinuities with respect to the available steep topography. The rock slope failure analysis both at discrete locations and in a distributed manner in a Geographic Information System further revealed that unfavourable geometric disposition of discontinuities at Theng rendered multiple modes of failure at critical locations, which is also corroborated by a very low Slope Mass Rating value (4.0) determined in this area, thus, making it difficult to suggest any cost-effective surface protection measure. However, analysis suggests slope dressing or re-excavation to contain future rock sliding in such cases, but the same appears to be difficult to implement on the ground because of unfavourable kinematic conditions of the vulnerable rock discontinuities. Accordingly, after evaluating the site conditions in detail, a short road tunnel with its probable tunnel rockmass conditions is proposed to bypass this active rock sliding stretch.     

2004年度墙体屋面材料及道路广场砖产品质量国家监督抽查结果

全行业产品质量逐年上升,企业重视管理和产品质量,抽查及检查企业合格率上升至93.1%,放射性核素限量未出现不合格。     

Use of molecular techniques for the analysis of foam-causing bacteria in Al Bireh oxidation ditch,Palestine

Activated sludge foaming, a worldwide problem, usually consists of filamentous bacteria occurring predominantly in the mixed liquor. Because of a lack of pure cultures of most filamentous bacteria and the limited amount of characterisation data, molecular approaches were used to investigate dominant filamentous bacterial strains associated with foaming in Al Bireh Wastewater Treatment Plant in Palestine. Applying denaturing gradient gel electrophoresis (DGGE), 16S rRNA cloning and sequencing showed the dominance of several filamentous bacteria including Microthrix parvicella, Nocardia sp., Hyphomicrobium facilis, Chloroflexi, Candidates TM7 and Nocardioides oleivorans.     

A hand method for predicting the stability of regular buildings,using frequency measurements

In combining two theoretical methods developed for the stability and frequency analyses of buildings and making use of experimental data obtained from the measurement of the fundamental frequency, a simple and reliable procedure is presented for the determination of the global critical load of regular building structures. It can be used for checking the stability and assessing the structural performance of existing buildings. The procedure is based on a closed‐form solution and design tables facilitating prompt calculation and can be carried out in minutes. The experimental data needed for the procedure is the fundamental frequency of the building, which can be obtained from standard measurements. The validity of the procedure is not dependent on the height of the building; it is equally applicable to low, medium‐rise and tall buildings. The results of tests on a small‐scale model are given for verification purposes. A worked example shows the easy use of the method. Copyright © 2003 John Wiley & Sons, Ltd.     

Multivariate analysis for assessing the quality of stormwater from different Urban surfaces of the Patiala city,Punjab (India)

Land use modifications associated with urbanization, such as clearance of vegetation, replacement of previously pervious areas with impervious surfaces and drainage channel modifications, result in increased runoff volumes, which often create flooding hazards and increase pollutant transport. An attempt has been made in the present study to investigate stormwater quality from five different urban sub-watersheds (that differ in land use and development activities) in the city of Patiala, India. The five sub-watersheds have similar geological, topographical and climatic conditions and were chosen to minimize the effect of these characteristics on stormwater quality and quantity. Stormwater samples were collected during six storm events between April 2010 and March 2011 and analyzed for BOD₅, COD, TSS, TDS, Oil and Grease, TKN, Total P, Coliforms and Heavy Metals (Zn, Cd, Ni, Pb, Fe and Cu). Results of the investigation indicate a strong correlation between land use and development activities and the resulting stormwater quality. TSS, COD and Oil and Grease were found to be major pollutants in surface runoff generated from commercial and urbanized catchments (all exceeded the surface water quality standards developed by Central Pollution Control Board, India). The water quality of the smaller residential catchment was better as compared to other catchments. Principal component analysis was investigated to identify linkages between stormwater quality and urban surface types. It was also confirmed through regression analysis that both antecedent dry period and rainfall intensity have telling influence on stormwater quality. Results obtained can provide practical information for improved stormwater management.     

Evaluation of microscopic techniques (epifluorescence microscopy, CLSM, TPE-LSM) as a basis for the quantitative image analysis of activated sludge

Microscopic techniques ranging from epifluorescence microscopy to confocal laser scanning microscopy (CLSM) and two photon excitation laser scanning microscopy (TPE-LSM) combined with fluorescent stains can help to evaluate complex microbial aggregates such as activated sludge flocs. To determine the application limits of these microscopic techniques, activated sludge samples from three different sources were evaluated after staining with a fluorescent viability indicator (Baclight Bacterial Viability Kit, Molecular Probes). Image analysis routines were developed to quantify overall amounts of red and green stained cells, location of stained cells within the flocs, and the spatial organization in clusters and filaments. It was found that the selection of the appropriate microscopic technique depends strongly on the type of microbial aggregates being analyzed. For flocs with high cell density, the use of TPE-LSM is preferred, since it provides a clearer image of the internal structure of the aggregate. Epifluorescence microscopy did not allow to reliably quantify red stained cells in dense aggregates. CLSM did not adequately image the internal filamentous structure and the location of stained cells within dense flocs. However, for typical activated sludge flocs epifluorescence and CLSM proved adequate.     

A unified energy formulation for the stability analysis of open and closed thin-walled members in the framework of the generalized beam theory

Generalized beam theory—GBT—is among the most adequate tools for the analysis of thin-walled prismatic elements. It enables the analysis of the distortion of the element cross-section and local buckling of individual walls in a unified manner that incorporates the results from classical bending theory. The basis of this theory was developed in the 1960s by Schardt for first and second order elastic behaviour of thin-walled members.Open and closed thin-walled members present the distinctive difference of the unknown shear flow that characterizes the latter. More specifically, shear strains must follow an elasticity law, as opposed to the simplifying assumptions for open cross-sections.It is the purpose of the present paper to present a unified energy formulation for the non-linear analysis of both open and closed sections in the framework of GBT, able to deal with all modal interaction phenomena between local plate behaviour, distortional behaviour and the more classical global (flexural, torsional and flexural–torsional) response. Finally, an application to the stability analysis of a compressed thin-walled column is presented and discussed.