Efficiency analysis of open trench for impact pile driving through a single-variable method

Abstract

The ground vibrations during pile driving operation have a drastic potential to undermine the surrounding structures both in land and reclaimed land. Particularly, reclaimed land necessitates ample application of pile driving due to the weak land condition. To prevent the structural damage, attenuation of the ground vibrations to an allowable level through active isolation of circular open trench is the scope of this study. In this research, finite element simulations of continuous impact pile driving process from the ground surface was executed with particular attention to the pile-soil interaction, and thereby, the efficiency of open trench application in attenuation of the unsafe distance of different structures was surveyed using the vibration sensitivity degree. Regarding the crucial parameters of an open trench (depth, width, and location), it was concluded that a sufficient high depth can attenuate the unsafe distance up to 68%, the trench width variations are less effective, and an average pile-trench distance is the most efficient option. The excavation volume was also concluded as another crucial parameter in open trench design which takes all three parameters into account. The trench depth equal to the pile’s maximum critical depth of vibration was inferred for an optimum design.     

People and community as constituent parts of hazards: the significance of societal dimensions in hazards analysis

Nature-triggered hazards and disasters have traditionally been treated only from the lens of geophysical and biophysical processes, implying that the root cause of large-scale death and destruction lies in the natural domain rather than in a coupled human–environment system. Conceptually, the physical domain has been seen as discrete and separate from human entities, and solutions were sought in the technological intervention and control of the physical environment—solutions that often ended up being less effective than hoped for and sometimes even counter productive. At all levels, institutions have directed and redirected most of their financial and logistical resources into the search for scientific and engineering solutions without allocating due attention and resources towards the assessment of effects and effectiveness of the applications of such technological outcomes. However, over the last two decades, forceful criticisms of the ‘dominant’ technocratic approach to hazards analysis have appeared in the literature and consequently there has not only been a shift in thinking of causation of disaster loss in terms of human vulnerability, but also newer questions have arisen regarding distinguishing between the ‘physical exposure’ of people to threats and societal vulnerability, and linking them with propensity to hazards loss. Though the vulnerability/resilience paradigm has largely replaced the hazards paradigm within the social sciences and much of the professional emergency and disaster management communities, this shift of thinking has not progressed to much of the physical science community, decision-makers and the public, who have not yet accepted the idea that understanding and using human and societal dimensions is equally or more important than trying to deal and control nature through the use of technology. This special issue is intended to further the idea that the aspects of community and peoples’ power to mitigate, to improve coping mechanisms, to respond effectively, and recover with vigor against the environmental extremes are of paramount conceptual and policy importance.     

Risk Assessment,Emergency Preparedness and Response to Hazards: The Case of the 1997 Red River Valley Flood,Canada

The prevention and/or mitigation offlood disasters requires continual research, numerouscapital investment decisions, and high-qualitymaintenance and modifications of flood-controlstructures. In addition, institutional and privatepreparedness is needed. The experience offlood-control in North America has shown mixedoutcomes: while flood frequency has declined duringthe last few decades, the economic losses havecontinued to rise. Recent catastrophic floods havealso been linked to major structural interventions inthe region. The flood diversions may cause harmfuleffects upon the floodplain inhabitants by influencingflood levels in areas which are not normallyflood-prone. The increasing vulnerability of thefloodplain inhabitants poses new challenges and raisesquestions concerning the existing risk assessmentmethods, institutional preparedness and responses todisaster-related public emergencies, and local-levelpublic involvement in flood mitigation efforts.In the context of the catastrophic 1997 floods of theRed River Valley, Manitoba, Canada, this researchfocuses on two aspects of flood-related emergencygovernance and management: (i) the functions andeffectiveness of control structures, and (ii) theroles, responsibilities and effectiveness oflegislative and other operational measures. The studyconcludes that the flood-loss mitigation measures,both in terms of effects of control structures andinstitutional interventions for emergency evacuation,were not fully effective for ensuring the well-beingand satisfaction of floodplain inhabitants. Althoughorganizational preparedness and mobilization to copewith the 1997 flood emergency was considerable, theirsuccess during the onset of the flood event waslimited. Lack of communication and understandingbetween institutions, a reluctance to implementup-to-date regulations, and minimal publicparticipation in the emergency decision-making processall contributed to the difficulties experienced byfloodplain inhabitants.     

Atmospheric Hazards Preparedness in Bangladesh: A Study of Warning,Adjustments and Recovery from the April 1991 Cyclone

In probabilistic terms, Bangladesh is prone, to at least one major 'tropical cyclone' every year. This situation is primarily due to the geographical location of Bangladesh in tropical Asia, and to its concave coastline and shallow continental shelf. The devastating impact of such cyclones on humans stems from a combination of intense human occupation of the area, predominance of traditional sociocultural values and religion, the precarious socioeconomic conditions of the majority of the coastal inhabitants, and the lack of a coordinated institutional disaster planning and management strategy. Bangladesh has experienced several catastrophic environmental disasters during the last decade; among these events, the 1991 April cyclone was the most catastrophic in terms of both physical and human dimensions.An initial study was carried out in the coastal regions of Bangladesh less than two weeks after they were hit by the severe cyclone of 29 April 1991. This research examined the process through which warning of the impending disastrous cyclone was received by the local communities and disseminated throughout the coastal regions of Bangladesh. It was found that the identification of the threatening condition due to atmospheric disturbance, the monitoring of the hazard event, and the dissemination of the cyclone warning were each very successful. The present study followed up on the initial research by surveying 267 respondents with an elaborate survey instrument, focusing on the most crucial academic and planning issues identified in the 1991 study. In particular, the nature and characteristics of the cyclone preparedness of the coastal inhabitants were assessed by the study; other factors considered included rural-urban variations, mainland-island differences, the nature and role of previous knowledge, and the disaster experience.The survey results show the variety of indigenous adjustment mechanisms that help to rehabilitate the survivors; also visible are the profound roles played by the social inequality variables and the magnitude of physical vulnerability in influencing the disaster loss and recovery process. The study recommends that hazard mitigation policies should be integrated with national economic development plans and programs. Specifically, it is suggested that the cyclone warning system should incorporate the human response to warnings as its constituent part, and in this way accommodating human dimensions in its operational design.     

Communicating human health risks associated with disinfection by-products in drinking water supplies: a fuzzy-based approach

Chlorine used for the disinfection of water supplies can react with naturally occurring organic compounds and form potentially harmful disinfection by-products (DBPs). A risk index for two regulated groups of chlorinated DBPs—trihalomethanes (THMs) and haloacetic acids (HAAs), using fuzzy C-means (FCM) clustering algorithm and fuzzy rule-based modeling is proposed for risk communication. The proposed index evaluates the cancer and non-cancer risks individually for THMs and HAAs using the FCM algorithm. Subsequently, two different fuzzy rule-bases were used to evaluate the overall risk-index based on cancer and non-cancer risks. The overall risk-index will provide drinking water utilities with an effective communication tool for communicating aggregated water quality compliance. Simulated DBP occurrence data obtained from the City of Quebec, Canada, is used to demonstrate the application of this methodology.     

“Events and failures are our only means for making policy changes”: learning in disaster and emergency management policies in Manitoba,Canada

Natural Hazards - The Canadian Province of Manitoba has experienced many severe floods and other natural disasters, and in response municipal, provincial, and federal governments have developed...     

Patterns of Coping and Adaptation Among Erosion-Induced Displacees in Bangladesh: Implications for Hazard Analysis and Mitigation

The purpose of this research was to identify social, culturaland psychological aspects of riverbank erosion-induced displacement in the flood plainsof Bangladesh. Although considerable research has examined the social and economicimpacts of riverine hazards in Bangladesh, there has been a general neglect of associatedpsychosocial implications. The specific objectives of the study were to: (1) assess hazardawareness in relation to riverbank erosion, (2) determine the magnitude of psychologicaldistress associated with displacement, and (3) identify patterns of psychosocial copingand adaptation common to displaced persons in Bangladesh. Although displacees were foundto have a significantly higher level of distress than non-displacees, this was relatedprimarily to socioeconomic deprivation rather than to displacement per se. The findingsof this study showed that the constant threat of riverbank erosion has contributed to asubstantial disaster subculture in the riverine zones of Bangladesh. The commonly hypothesized factorssuch as loss of land and frequency and duration of displacement were notsignificantly associated with distress levels.The need to integrate into hazard analysis and mitigation studiesa social, cultural and psychological context is recommended. In Bangladesh, the poor copewith hardship and problems by relying on religion, which in turn significantlyinfluences how they perceive and interpret natural calamities. It is argued that the capacityof people to respond to environmental threats is a function of not only the physicalforces which affect them, but of indigenous social and cultural belief systems which influencehow people interpret and organize their activities. Hazard analysis and mitigation wouldbe most effective when it takes into account psychological and socio-cultural aspects ofdisasters, due to the fact that psychological distress impacts the capacity of people toachieve livelihoods, but also important social and psychological processes determine the waypeople perceive and adapt to natural hazards.