Two field studies of surface displacements during pipe bursting were conducted. The first field study consisted of a controlled experiment in clay soil. Three vitrified clay pipelines, each at a different burial depth, were up-sized to high density polyethylene (HDPE) pipes using static pipe bursting techniques. Surface displacements during the pipe bursting process were monitored using digital imaging techniques as well as surveying. It was found that ground displacements were largest in the vertical direction, such that the maximum vertical displacements measured during pipe bursting ranged from 71.8 ± 7.5 mm at a depth of cover of 0.6 m and 11.2 ± 1.2 mm at a depth of cover of 1.5 m. Transverse displacements generated during pipe bursting were found to correspond to tension cracking of the ground surface above the pipe. The second field study examined pipe bursting installations which took place at the Royal Canadian Mounted Police College campus in Ottawa, Ontario. During this study, five pipe bursting installations were monitored. Each installation varied in terms of the surface and subsurface conditions, host pipe size and material, replacement pipe size, and depth of cover. The pattern of displacements distributed in all three directions was consistent with the results from the controlled study. However, greater variability in results was found during the Ottawa project. Vertical displacements were found to range from 0.6 ± 0.1 mm to 11.3 ± 0.2 mm for pipe bursts carried out to the same up-size dimension, at approximately the same depth of cover, surrounded by similar surface and subsurface conditions. In general, pipe bursting in clayey soils with an unpaved surface resulted in larger displacements having a narrower distribution over the ground surface than the paved installations. Additionally, increased variability in results occurred under real construction conditions due to inherent variability in subsurface and host pipe conditions. / Thesis (Master, Civil Engineering) -- Queen's University, 2008-12-23 12:52:08.301

Submitted in fulfillment of the requirements of the Degree of Magister Technologiae: Civil Engineering, Durban University of Technology, 2013. / The urgent need to rehabilitate or replace ageing deteriorated buried potable water pipeline networks is one of the many critical service utility provision challenges faced within the municipalities in South Africa. The majority of these unreliable deteriorated pipeline networks consist of un-dipped (not coated with bitumen) AC piping which have long passed their planned economic and technical lifespan. Traditionally, the open trenching method has been utilised for the replacement of aged and deteriorated piping. However, this traditional open trenching method has shown to be expensive and difficult to implement, particularly in congested high traffic use urban areas. The need to rehabilitate or replace the ageing deteriorated buried potable water pipelines in South Africa, taking into account the above mentioned expensive factors has a solution. This solution is termed ‘trenchless technology’ and sometimes also termed ‘no dig’. Recent advancements in trenchless technologies now include innovative methods such as pipe bursting, close-fit lining and sliplining. Close-fit compact pipe manufactured by Wavin Overseas B.V. was newly introduced in South Africa in 2010 for the rehabilitation of deteriorated pipelines. These trenchless methods require further research into their technical application merits, drawbacks and costs in relation to the traditional open trenching method in order to determine which method is more expensive and also least suitable. Traditionally, the ‘total cost’ associated with pipe rehabilitation or replacement projects consisted only of the direct costs. The indirect and socio-economic inconvenience costs were often ignored and resulted in costly expenses to the municipalities. However, this research will show that these indirect and socio-economic inconvenience costs must form part of the total cost of a project as it assists with the successful completion of the project without expensive unforeseen costs to the municipalities. In addition, this research will provide insight as to which indirect and socio-economic inconveniences are dominantly experienced by the public. To achieve this, a quantitative socio-economic survey questionnaire was developed. This questionnaire was aimed at residents and business owners who were affected during a project of this nature. This research study will serve as a support tool to municipalities of South Africa when selecting a pipe rehabilitation or replacement method. This support tool will provide key technical merits and drawbacks of the traditional open trenching method, pipe bursting method, close-fit compact pipe method and sliplining method. In addition, this research study will compare the ‘total cost’ of the traditional open trenching method against the trenchless pipe bursting method. The decision making process lies in the hands of the municipal technical managers. Therefore, their knowledge and experience of up to date information on trenchless methods (as well as the traditional open trenching method) is vitally important. This research provides insight as to the knowledge and experience of technical municipal staff on trenchless methods, its application and use in South Africa. A quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at technical staff in the water departments of district and local municipalities of South Africa. The results of the above questionnaire surveys formed part of the eThekwini Water and Sanitation (EWS) Feasibility study funded by the Dutch Government. When comparing the costs of the trenchless pipe bursting method against the traditional open trenching method, the results revealed that trenchless methods are undoubtedly cheaper and far less disruptive to the public. The results of the socio-economic survey revealed that trenchless methods were preferred by the public since it was less disturbing and the hindrances experienced were also far less than the traditional open trenching method. The results of the technical municipal survey questionnaire revealed that at least 50% of municipal technical staff of South Africa are not adequately informed about trenchless methods, its application and technical merits and drawbacks respectively. This survey questionnaire revealed that South Africa may be advancing over the years on the use of trenchless methods, however, more educating in the form of training, seminars and other methods of marketing must be undertaken starting at a municipal level.

Polymer pipes, typically high density polyethylene (HDPE), can be pulled-into-place, avoiding traditional cut-and-cover construction, using pipe bursting and horizontal directional drilling (HDD) pipe installation techniques. Of particular interest, are the ground displacements, induced by cavity expansion, associated with these techniques and the strains that develop in existing pipes in response to these displacements. Further, the axial stress-strain response of the new HDPE pipe during and after the cyclic pulling force history required to pull the pipe into place is of interest. Surface displacements and strains in an adjacent polyvinyl chloride (PVC) pipe induced by static pipe bursting were measured during the replacement of a new unreinforced concrete pipe. For the pipe bursting geometry tested, the maximum vertical surface displacement measured at the ground surface was 6 mm, while the distribution of vertical surface displacements extended no more than 2 m on either side of the centreline. The maximum longitudinal strain measured in the PVC pipe was less than 0.1% and its vertical diameter decreased by only 0.5%, suggesting that pipe bursting did not jeopardize the long-term performance of the water pipe tested. In addition, results from identical stress relaxation and creep tests performed on whole pipe samples and coupons trimmed from a pipe wall were compared, and these demonstrated that the coupons exhibited higher modulus than the pipe samples. Therefore, isolated pipe samples, as opposed to coupons, were tested to quantify the stress-strain response of HDPE pipe during the simulated installation, strain recovery, and axial restraint stages of HDD. Axial strains were found to progressively accumulate when an HDPE pipe sample was subjected to the cyclic stress history used to simulate an HDD installation. It was shown that existing linear and nonlinear viscoelastic models can serve as predictive design tools for estimating the cyclic strain history of HDPE pipe during installation. For the specific conditions examined, the tensile axial stresses redeveloped in the pipe samples, once restrained, were not large enough to lead to long-term stress conditions conducive to slow crack growth even when the short-term performance limits were exceeded by a factor of 1.5. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-04-01 18:19:24.434