Search results

Geophysical methods are widely applied for the prognostication of natural and technogeneous risks. Especially effective is their application in the sphere of engineering geology and the ore exploration industry. The effectiveness of geophysical methods is convincingly illustrated by the concrete results obtained in studies, performed to solve specific problems. This paper presents an overview of methods and studies in the field of natural and technogeneous risks by the application of geophysical surveying. In a case study focusing on opencast coal exploration in the area of Maritza‐East, the usefulness of geophysical methods in mapping the hard rock inclusions in the overburden of the lignite mines is outlined. The possibilities of using such technologies for guiding the process and the reduction of technogeneous risks during exploration are outlined.

The purpose of this paper is to show that Uttaranchal is a hilly State, recently constituted in the Himalayan region. Over 80 percent of Uttaranchal state is prone to slope instability because of weak and highly folded and fractured rocks, steep slopes, high seismicity and unfavorable hydro‐geological conditions. In addition to this, unsystematic development construction activities contribute to the problem. Newly formed Uttaranchal state is in the process of development, required to expand the existing infrastructure.

The paper gives a full description: Bending of rock beds, their disjointing, disruption and drag‐folding are characteristic features of a creeping mass. Tilted trees and poles are indicative of creep movement as seen on a number of hillslopes in and around Nainital town. The curvature of the tree trunks bears record to the rate of creep during the period of growth of the tree. It hardly needs stating that the rate of creep movement is quicker during the rainy season, and there may be long periods stretching over years when no movement at all takes place. The temporal span of this phenomenon stretches over thousands of years. The rate is accelerated by clear‐felling in forests and by construction on steeper slopes. The depth of the creep movement is variable, and depends largely on the nature and degree of weathering of rocks, the sub‐surface structure and amount of water present within.

It was found that, to meet the requirement, construction activities are in full pace, which have given rise to the new landslide problems or have aggravated the existing slope instability problems. In order to keep the landslide problems to a minimum, systematic studies are required on every aspect of the slope instability problems.

On the basis of slope instability evidence, past occurrence of landslides, deformation of civil structures and geological conditions, three zones have been identified – safe, moderately safe, and very unsafe.

The paper describes the natural problems with which Uttaranchal is faced and proposes systematic studies which are required to deal with every aspect of the outstanding problems of slope instability.

The design of cantilever pile walls (CPWs) presents several common challenges. These challenges include soil variability, groundwater conditions, complex loading conditions, construction considerations, structural integrity, uncertainties in design parameters and construction and monitoring costs. Accordingly, this paper is to provide a detailed literature review on the design criteria of CPWs, specifically in cohesionless soil. This study aims to present a comprehensive overview of the current state of knowledge in this area.

The paper uses a literature review approach to gather information on the design criteria of CPWs in cohesionless soil. It covers various aspects such as excavation support systems (ESSs), deformation behavior, design criteria, lateral earth pressure calculation theories, load distribution methods and conventional design approaches.

The review identifies and discusses common challenges associated with the design of CPWs in cohesionless soil. It highlights the uncertainties in determining load distribution and the potential for excessive wall deformations. The paper presents various approaches and methodologies proposed by researchers to address these challenges.

The paper contributes to the field of geotechnical engineering by providing a valuable resource for geotechnical engineers and researchers involved in the design and analysis of CPWs in cohesionless soil. It offers insights into the design criteria, challenges and potential solutions specific to CPWs in cohesionless soil, filling a gap in the existing knowledge base. The paper draws attention to the limitations of existing analytical methods that neglect the serviceability limit state and assume rigid plastic soil behavior, highlighting the need for improved design approaches in this context.

A numerical technique is described for the analysis of multiple interacting deformable bodies undergoing large displacements and rotations. Each body is considered an individual discrete unit, which is idealized by a finite element model. Discrete finite element models interact with their surroundings through contact stresses, which are continually updated as the elements move and deform. The method of analysis consists of a finite element formulation based on a generalized explicit updated Lagrangian method. This formulation is a general finite element formulation, that permits the large deformation analysis of both continuum and discontinuum systems. Different validations of the proposed method of analysis, including cases that involve very large rotations, as well as some examples that demonstrate the application of the discrete finite element method to problems in rock mechanics are presented and discussed in the paper.

Environmental pollution has increased as a result of modern settlements' expanding demand and rapid population growth. In Ebonyi State, Nigeria, quarrying is one of the activities that has an impact on the environment and ecosystem. The aim of the study is to assess stream water’s quality in order to ascertain how quarry operations affect the streams’ water quality. The present study investigated the environmental impact of quarrying on the physicochemical properties of surface water in Ebonyi State, Nigeria.

A total of 288 surface water samples were taken in 2018, 2019 and 2020 from quarry locations and a Control location for the determination of physicochemical properties and heavy metal contents using standard analytical methods. Datasets were analysed using Fisher’s significance least difference (F-LSD) at the 0.05 probability level.

This study discovered that surface waters around quarries are severely polluted, according to the results of the physico-chemical and heavy metal contents of the surface waters. Most of the physical and chemical properties of the water downstream of the Ishiagu, Umuoghara and Ngbo did not meet World Health Organisation (WHO) standards, such as colour and pH. The heavy metal levels in the Ishiagu, Umuoghara and Ngbo streams were above WHO criteria for Pb, Cd and Fe. The results point to the obvious conclusion, without prejudice to other unexplained factors that the pollution is most likely the result of quarry contamination. Strict measures should be taken to regularly monitor the water quality of the streams.

This study focused on the assessment of physicochemical properties using standard analytical methods to evaluate the environmental impact of quarrying on surface water qualities. The study used the World Health Organisation (WHO, 2011) water guideline as a standard to compare with the study dataset and control measures.

Climatic conditions as also the agrarian economy of the Indian subcontinent is greatly affected by the monsoonal winds that are characterized by heavy rains between June and September. The paper is an attempt to break the myth that landslides are only confined to monsoonal months that normally have concentrated rains and can be expected in other seasons as well and, therefore, disaster alert levels cannot be relaxed during non‐monsoonal season. The communication also attempts to identify slowly ongoing weathering processes that might cause to slope failure without rains and, therefore, paves way for identifying similar landslide prone areas.

The paper discusses two landslides of the recent past; Uttarkashi landslide of 23 September 2003 and Ramolsari landslide of 30 March 2005 that took place after the seizure of the monsoonal rains and is based upon the first hand field observations of the authors. The paper discusses the likely causes of the slides along with the implications of this new trend of landslides taking place in the non‐monsoonal season upon the disaster management strategy of the state.

The investigations reveal that precipitation could be considered the trigger in case of Uttarkashi landslide but there exist no evidences to suggest that the Ramolsari landslide could have been triggered by increased pore water pressure. Slow ongoing and hard to observe processes of weathering seem to have initiated this slide.

For the purpose of metrological parameters, the study relies upon the data of the state run rain gauges that do not have an appreciably good spatial distribution. Rainfall data of the nearest observation points is, therefore, taken as representative of the rainfall in the area under present focus. For Ramolsari, the rainfall data of Tehri is used while Uttarkashi has a rainfall recording observatory.

The paper highlights the importance of keeping the preparedness levels high for prompt post‐disaster operations all through the year. This paper advocates redefining high alert period for landslide hazard and for following high alert all through the year particularly in areas prone to landslides.

Current methods for floodway design are predominately based on hydrological and hydraulic design principles. The purpose of this paper is to investigate a finite element methods approach for the inclusion of a simplified structural design method into floodway design procedures.

This research uses a three-dimensional finite element method to investigate numerically the different parameters, geometric configurations and loading combinations which cause floodway vulnerability during extreme flood events. The worst-case loading scenario is then used as the basis for design from which several structural design charts are deduced. These charts enable design bending moments and shear forces to be extracted and the cross-sectional area of steel and concrete to be designed in accordance with the relevant design codes for strength, serviceability and durability.

It was discovered that the analysed floodway structure is most vulnerable when impacted by a 4-tonne boulder, a 900 mm cut-off wall depth and with no downstream rock protection. Design charts were created, forming a simplified structural design process to strengthen the current hydraulic design approach provided in current floodway design guidelines. This developed procedure is demonstrated through application with an example floodway structural design.

The deduced structural design process will ensure floodway structures have adequate structural resilience, aiding in reduced maintenance and periods of unserviceability in the wake of extreme flood events.

The purpose of this paper is to develop a numerical (finite-difference) model exploring phase and group velocities of SH-wave propagation in initially stressed transversely isotropic poroelastic multi-layered composite structures and initially stressed viscoelastic-dry-sandy multi-layered composite structures in two distinct cases.

With the aid of relevant constitutive relations, the non-vanishing equations of motions for the propagation SH-wave in the considered composite structures have been derived. Haskell matrix method and finite-difference scheme are adopted to deduce velocity equation for both the cases. Stability analysis for the adopted finite-difference scheme has been carried out and the expressions for phase as well as group velocity in terms of dispersion-parameter and stability-ratio have been deduced.

Velocity equations are derived for the propagation of SH-wave in both the composite structures. The obtained results are matched with the classical results for the case of double and triple-layered composite structure along with comparative analysis. Stability analysis have been carried out to develop expressions of phase as well as group velocity in terms of dispersion-parameter and stability-ratio. The effect of wavenumber, dispersion parameter along with initial-stress, porosity, sandiness, viscoelasticity, stability ratio, associated with the said composite structures on phase, damped and group velocities of SH-wave has been unveiled.

To the best of authors’ knowledge, numerical modelling and analysis of propagation characteristics of SH-wave in multi-layered initially stressed composite structures composed of transversely isotropic poroelastic materials and viscoelastic-dry-sandy materials remain unattempted inspite of its importance and relevance in many branches of science and engineering.

The prediction of soil erosion by the action of water has been based largely on the universal soil loss equation and its variations, derived from data collected from agricultural land in the USA. Open pit mining creates waste rock or spoil dumps at the angle of repose of the material (typically 35° to 40°). Even after regrading these slopes, relatively steep slope angles will remain, typically steeper than 6° to 8°. Topsoiling is generally required to facilitate revegetation, but bare topsoil is particularly prone to erosion. Mine slopes are therefore quite unlike the agricultural slopes on which the predictive tools for erosion by water were based. The paper discusses the prediction of erosion from steep mine waste slopes in the light of some erosion data collected from laboratory flume and field studies for open pit coal and gold mining situations in Queensland, Australia. Alternative interpretations of the data are presented, which result in different trends when the data are extrapolated up to angle of repose slopes. The effectiveness of both coarse‐grained riprap on the surface and revegetation in limiting erosion are highlighted.

This paper aims to investigate the effect of frictional materials and surface texture on the energy conversion efficiency and the mechanical output performance of the ultrasonic motor (USM).

A newly designed testing system was set up to measure the mechanical output performance of the USM. The influence of different frictional materials on the output performance of the USM was studied under the same assembly process and parameters. The surface texture was fabricated by laser ablation processing. The effects of surface texture and input parameters on the energy conversion efficiency and mechanical output performance of the USM were studied.

The results show that polyimide (PI) composites as frictional material can significantly improve the output performance of the USM compared to polytetrafluoroethylene (PTFE) composites. When the pre-load is 240 N, the energy conversion efficiency of the USM using textured PI composites as frictional material can reach 41.93 per cent, increased by 29.21 per cent compared to PTFE composites, and the effective output range of the USM is increased to 0.7-1.1 N m. Besides, the pre-load and surface texture have a great influence on the output performance of the USM.

PI composites can improve the mechanical output performance of the USM. Surface texture can also improve the interface tribological properties and the energy conversion efficiency based on the advanced frictional materials, which will contribute to the increment of the output performance of the USM under the same input conditions.