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1 – 10 of 590DARREN SCOTT and CHIMAY J. ANUMBA
The engineering management of housing subsidence cases is an important field of work for many UK engineers, and remains of enduring interest to householders, insurers and other…
Abstract
The engineering management of housing subsidence cases is an important field of work for many UK engineers, and remains of enduring interest to householders, insurers and other parties involved in the construction and maintenance of residential buildings. There are often difficulties in the diagnosis and repair of buildings subject to subsidence damage due to several factors, including the complex interaction between the various causative agents, the lack of a systematic investigation procedure, and the large number of available courses of remedial action. In many cases, inaccurate diagnosis of the subsidence problem has resulted in expensive remedial measures which are either unnecessary or inappropriate (and fail to arrest the movement). This paper reviews the management of subsidence cases and describes the development of a knowledge‐based system intended to improve existing procedures by ensuring greater accuracy, consistency and effectiveness of the management regime adopted by engineers. The system addresses three key aspects of the management procedure: initial diagnosis, choice of an appropriate course of investigations, and the specification of effective remedial measures. The benefits of the knowledge‐based system are contained in the concluding section of the paper.
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Outlines the application of technology used in detecting andremedying the problems caused by subsidence and settlement, and theresponsibility placed on surveyors in detecting it…
Abstract
Outlines the application of technology used in detecting and remedying the problems caused by subsidence and settlement, and the responsibility placed on surveyors in detecting it. Proposes that a clearly defined serviceability limit would reduce disputes about whether or not acceptable subsidence or settlement had occurred. Discusses the changes in definitions brought about through new legislation and developing standards. Explores the main difficulties with subsidence and highlights subsidence blight. Explains the role of insurance companies and the changes taking place with insurance premiums, and calls for the implementation of clear definitions of such things as unacceptable subsidence, professional negligence and management of subsidence claims. Investigates three stages of remedial works: the work necessary to stabilize the foundations and thus prevent future damage; the structural repair of the building necessary to restore the stability and structural integrity; and the decorations and finishes. Proposes the need for deeper foundations for new buildings on shrinkable clay soils and alternatives to underpinning. Suggests changes that could give further help to the insurer by changing the expectations of the homeowner and declares that the problem has been mishandled and misunderstood by insurers.
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G. Shabha and K. Kuhwald
Aims to investigate the problems of subsidence and theirimplications for domestic buildings by addressing a number of questions.What are the main causes of land subsidence? What…
Abstract
Aims to investigate the problems of subsidence and their implications for domestic buildings by addressing a number of questions. What are the main causes of land subsidence? What is the potential damage of subsidence, and how can this be prevented and reduced? What are the financial and legal implications for all those involved? Looks critically at the effect of subsidence due to coal mining on residential properties and the particular problems encountered by valuation surveyors. Briefly examines the history and past operation of the compensation system to assess its effectiveness. Finally, considers the fears inherent following privatization, along with future proposals.
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Margaret MacQueen, Michael Lawson and Wen-Nyi Ding
In the UK, responses to intense weather events regarding national and regional level perils include the support of a General Insurance policy at the address level as part of…
Abstract
Purpose
In the UK, responses to intense weather events regarding national and regional level perils include the support of a General Insurance policy at the address level as part of private residential and other insurance policies covering the key risks of flooding, subsidence and windstorm. In respect of the subsidence peril, dry summers can lead to many thousands of properties on shrinkable clay soils suffering differential downward movement as water is abstracted from the soil by vegetation. These events are forecast to increase in frequency and severity due to climate change, with costs for a dry event year of more than £500m to UK insurers. Assessing the character of these event years can inform government, local government, insurers and their agents as to the typical characteristics of an event year and its impacts. The purpose of this paper is to provide a comprehensive overview of the 2018 UK subsidence event year as it relates to trees and low rise buildings.
Design/methodology/approach
The research material is taken from claims that originated within the period commencing in the Summer of 2018, which in the UK was dry and with high levels of claim notification, and is from the private database of Property Risk Inspection Limited, one of the largest UK specialist subsidence claims handling businesses.
Findings
The data clearly illustrates the wide range of vegetative species causing or contributing to claims in the UK, their age ranges, sizes and conditions, management options and the range of land uses and statutory controls that exist in relation to title and other boundaries.
Originality/value
There have been various small-scale studies looking at individual cases of subsidence and the impacts of vegetation, but there have been no detailed investigations of large-scale claims-driven events such as the 2018 surge. The importance of this population-level investigation will only increase given the modelling for increased hot and dry summers over the coming decades.
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Raffaella Santagiuliana, Massimo Fabris and Bernhard Aribo Schrefler
The purpose of this paper is to give an explanation of the new data available about surface subsidence above the depleted gas reservoir Ravenna Terra. These data confirm the…
Abstract
Purpose
The purpose of this paper is to give an explanation of the new data available about surface subsidence above the depleted gas reservoir Ravenna Terra. These data confirm the existence after end of exploitation of a reversed subsidence bowl with minimum subsidence above the reservoir, as opposed to conventional subsidence bowls during exploitation which show maximum subsidence in the same location.
Design/methodology/approach
The paper analyses these new data about the existence after end of exploitation of a reversed subsidence bowl. The observed behaviour is reproduced successfully with a fully coupled two phase flow code in deforming reservoir rocks which incorporates a constitutive model for partially saturated porous media.
Findings
The paper provides successful simulations. These allow affirming with confidence that the explanation for the peculiar behaviour is reservoir flooding and partially saturated rock behaviour.
Research limitations/implications
Further research: other case studies where similar behaviour is expected, e.g. Ekofisk.
Practical implications
The paper includes implications for better management of reservoir exploitation schedules to minimize the observed phenomenon.
Originality/value
This paper explains the peculiar behaviour of subsidence above the depleted gas reservoir Ravenna Terra and confirms the conjecture that constitutive behaviour of partially saturated rocks is the origin of the observed phenomenon.
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It is observed that the slow onslaught disasters do not normally catch media attention as these often do not result in human casualties. Inadequate media attention results in…
Abstract
Purpose
It is observed that the slow onslaught disasters do not normally catch media attention as these often do not result in human casualties. Inadequate media attention results in insufficient rehabilitation support for the victims. The paper aims at highlighting the problem of ground subsidence in the Himalayan terrain together with the hardships of the victims.
Design/methodology/approach
The paper is based on the detailed field investigations carried out by the author in the remote Himalayan habitations of Garbyang in Dharchula block of Pithoragarh, Talla Dhumar and Umli‐Bhandarigaon in Munsyari block of Pithoragarh and Bagi in Uttarkashi district in the state of Uttaranchal in India. All these habitations are being affected by ground subsidence and the inhabitants of these villages are facing severe resource crisis.
Findings
Garbyang village in Central Himalaya is observed to be situated over the varve deposits laid down in the proglacial lake abutting against Chialekh ridge and is witnessing the problem of ground subsidence resulting in the destruction of the once thriving and prosperous habitation. The studies relate the subsidence at Garbyang with the seismicity in the region as also the subsequent toe erosion and downslope mass movement. The other sites discussed in the paper are witnessing the problem of ground subsidence due to the active toe erosion by rivers and streams.
Research limitations/implications
There exist no records of the exact date of initiation of the ground subsidence in the investigated areas and these are grossly based on the information provided by the village elders.
Originality/value
The article would help in making the disaster managers responsive to the problems the masses are facing due to ground subsidence in this fragile zone and this would result in mustering resources for reducing the hardships of the masses.
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Chimay Anumba and Darren Scott
Notes that the management of subsidence cases often involves both engineering consultants and contractors. In order to obtain information on current trends in subsidence…
Abstract
Notes that the management of subsidence cases often involves both engineering consultants and contractors. In order to obtain information on current trends in subsidence management, a survey of both consultants and contractors who deal with subsidence cases was undertaken. Presents the findings of the survey which highlight both elements of good practice and areas for improvement. Also reveals inconsistencies in the procedures adopted by different firms as well as differences between the approaches adopted by consultants and contractors. The results of the survey are being incorporated into the development of a knowledge‐based system for the management of subsidence cases.
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Describes the format and scope of a database of predominantly technical information relating to subsidence and heave claims on shrinkable/expansible clay soils. The database…
Abstract
Describes the format and scope of a database of predominantly technical information relating to subsidence and heave claims on shrinkable/expansible clay soils. The database includes information on 484 individual subsidence claims, comprising details of the property and its structure, the damage, ground and foundation conditions, vegetation, and monitoring and remedial measures. The data are analysed and implications for the investigation of subsidence claims are examined. The analyses indicate that, among other results: detached properties have greater susceptibility to subsidence or heave claims than non‐detached properties; properties built prior to 1900 are less susceptible to damage than those built in the 1900‐1944 period; there are no reasons to be concerned over current minimum depth requirements for construction in shrinkable/expansible clays; and London clay is the most commonly encountered “problem” soil.
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Bong-Kuk Ko, Woo-Jung Lee and Jae-Hoon Lee
The purpose of this study is to understand what health and safety hazards low-income households are subject to by surveying the real conditions of the defective housing of…
Abstract
The purpose of this study is to understand what health and safety hazards low-income households are subject to by surveying the real conditions of the defective housing of low-income households, and to find improvement strategies. For this purpose, we visited the concentrated areas of the multi-dwelling unit (MDU) (also known as multi-family residential) housing in Jungwon-gu and Sujeong-gu in Seongnam City, Kyunggi-do, one of the representative areas in Korea with a massive distribution of the low-income class. Based on the survey data, the level of housing defects were comparison analyzed per income decile (decile 1, decile 2, deciles 3–4), and per housing location, in the categories of subsidence, cracks in the wall, delamination, water leakage/infiltration, condensation, and contamination. The housing condition per income class was more defective in the decile 2 households rather than in the decile 2 households, and in the substructure more than in the superstructure. Among the six defects, contamination problems, caused by sub-standard living conditions, were the most frequent cases. Structural defects, subsidence and cracks in the wall, were found in the main living areas—the bedrooms and the living rooms. It was confirmed in this study that the conditions of low-income housing are serious, and that it is necessary to explore specific countermeasures in the near future.
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Peter Wynn and Graham Hardiment
Examines whether surveyors engaged in mortgage valuation inspections using questionnaire‐style report forms supplied by lending institutions are subject to an increased risk of…
Abstract
Examines whether surveyors engaged in mortgage valuation inspections using questionnaire‐style report forms supplied by lending institutions are subject to an increased risk of liability in respect of identifying the present and future threat of subsidence to domestic properties. Analysis of the mortgage valuation report forms used by 34 different lending institutions showed that 20 per cent failed to ask any subsidence‐related questions, only 6 per cent asked about the geology or soil type of the site, and only 9 per cent asked about the location of trees relative to the building. Evaluation of the report forms showed that the type, quality and quantity of questioning were such that 24 out of the 34 were inadequate and unreliable, leaving the surveyor at an increased risk of litigation.
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