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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…
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.
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.
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…
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.
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 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.
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.
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.
Further research: other case studies where similar behaviour is expected, e.g. Ekofisk.
The paper includes implications for better management of reservoir exploitation schedules to minimize the observed phenomenon.
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.
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.
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.
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.
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.
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.
Notes that the management of subsidence cases often involves both engineering consultants and contractors. In order to obtain information on current trends in subsidence…
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.
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.
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…
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.
Examines whether surveyors engaged in mortgage valuation inspections using questionnaire‐style report forms supplied by lending institutions are subject to an increased…
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.
This paper presents the findings of a research project which investigates the market for the chartered building surveyor to act as the “panel expert” for insurance…
This paper presents the findings of a research project which investigates the market for the chartered building surveyor to act as the “panel expert” for insurance companies in domestic subsidence claims cases. The key players in the process of a claim are considered and hypotheses, that building surveyors are discriminated against in favour of engineers, and that this is due to the training of each profession, are stated. The hypotheses are tested by questionnaire studies of building surveying firms, insurance companies, loss adjusters and higher education institutions. The hypotheses are largely confirmed but the results throw interesting light on the subject. The paper concludes with recommendations for professional bodies and universities to assist those surveyors wishing to practise in an increasingly important area of work.