Laboratory and Field Performance of Buried Steel-Reinforced High Density Polyethylene (SRHDPE) Pipes in a Ditch Condition under a Shallow Cover

Metal and plastic pipes have been used extensively as storm sewers and buried drainage structures in transportation projects. Metal pipes have high strength and stiffness but are susceptible to corrosion from wastewaters containing acid, and from aggressive soils. Plastic pipes are resistant to corrosion, erosion, and biological attack but have certain disadvantages including lower long-term strength and stiffness (dimensional reliability), buckling, and tearing of pipe wall. To address the disadvantages of metal and plastic pipes, a new product, steel-reinforced high-density polyethylene (SRHDPE) pipe, has been developed and introduced to the market, which has high-strength steel reinforcing ribs wound helically and covered by corrosion-resistant high density polyethylene (HDPE) resin inside and outside. The steel reinforcement adds ring stiffness to the pipe to maintain the cross-section shape during installation and to support overburden stresses and traffic loading. The HDPE resin protects the steel against corrosion and provides a smooth inner wall. The combination of steel and plastic materials results in a strong and durable material with a smooth inner wall. Different methods are available for the design of metal and plastic pipes. The American Water Works Association (AWWA) Manual M11 (2004) provided the design procedure for metal pipes and the 2007 ASSHTO LRFD Bridge Design Specifications had separate design procedures for metal and plastic pipes. However, it is not clear whether any of these procedures for metal and plastic pipes can be used to design an SRHDPE pipe. Moreover, no approved installation or design specification is available SPECIFICALLY for the SRHDPE pipes. Some research has been conducted on SRHDPE pipes to understand the performance of SRHDPE pipes in the laboratory including the laboratory tests conducted by Khatri (2012). To investigate the performance of the pipe with various backfills, in addition to the laboratory tests conducted by Khatri (2012) with the sand backfill, a laboratory test with the crushed stone backfill was conducted in a ditch condition under 2 feet of shallow cover. This was performed in a large geotechnical testing box 10 feet long x 6.6 feet wide x 6.6 feet high. Based on the laboratory testing and analysis on the SRHDPE pipes, it can be concluded that (1) the pipe wall-soil interface should be designed as a fully bonded interface to be conservative, (2) the Giroud and Han (2004) method and the simplified distribution method in the 2007 AASHTO LRFD Bridge Design Specifications reasonably predicted the pressures on the top of the SRHDPE pipes induced by static and cyclic loadings, (3) the modified Iowa formula (1958) under predicted the deflections of the SRHDPE pipes during the installation and over-predicted the deflections during static and cyclic loadings, (4) the formula provided by Masada (2000) can be comfortably used to determine the ratio of the vertical to horizontal deflection of the SRHDPE pipe, (5) the pipe wall area was enough to resist the wall thrust during installation and loadings, and (6) the highest measured strains recorded in steel and plastic during the installation and loadings in all the tests were within the permissible values. The laboratory tests however have some limitations. For example, the installation procedure of the pipe in the test box may be different from the field installation due to the limited space and construction equipment in the laboratory. The laboratory box tests may have a boundary effect. Therefore, a field test was conducted to verify the lab test results The results obtained in the field test were found in agreement with the results obtained for the laboratory test during the installation and the traffic loading

Description of Sand-Water Pumping Experiment and Preliminary Photographic Investigation

The objective of this report is threefold: to provide a brief description of the Sand-Water pumping experiment; to describe the flow of sand and water in the experimental equipment; and to present the results of a preliminary photographic investigation of fluorescent minerals in clear plastic pipes

The ultrasonic nondestructive evaluation of welds in plastic pipes.

Imperial Users onl

Effect of woodstack structure on invertebrate abundance and diversity

Reduced quantities of dead wood in managed forests have resulted in a reduction in the abundance and diversity of saproxylic invertebrates to the extent that many are now considered red list species. To mitigate against this loss, one conservation measure is the provision of dead wood, in the form of piles of chopped logs, i.e. ‘woodstacks’. The heterogeneity and volume of dead wood habitat is considered to be an important component of habitat suitability. However, the value of different woodstack types to invertebrate conservation has rarely been quantified and there is little consensus on how to best to survey the invertebrate fauna of woodstacks. This study used both sticky traps and pitfall traps to sample the invertebrate fauna of three types of sycamore woodstack. Woodstacks were made from 10 logs, 20 logs and 10 scorched logs plus a control woodstack made of unplasticised polyvinyl chloride (uPVC) plastic piping and observed over a 4-week period. A total of 1446 invertebrates from 16 orders, including 127 Coleoptera, were caught during the sampling period. A generalized linear model was used to analyse invertebrate abundance between woodstack and between trap types, and diversity was determined using Shannon diversity indices and analysed using a two-way Analysis of Variance (ANOVA). The woodstack type had no effect on the abundance of invertebrates. However, Shannon diversity was highest on the scorched woodstacks, with little difference between the 10 and 20 log stacks and the control uPVC woodstacks. However, closer inspection of orders revealed the uPVC woodstacks to have the lowest abundance and diversity of Coleoptera. This study suggests that constructing woodstacks can provide suitable habitat for a variety of invertebrates. However, these invertebrates may have simply used the structures for shelter and the true value with saproxylic invertebrates could not be measured in this 4-week study. To fully appreciate the conservation value of woodstacks will require longer term studies that examine how and when saproxylic invertebrates use dead and decaying wood

Assessment of Road Crossings for Improving Migratory Fish Passage in the Winnicut River Watershed

This report summarizes the results of a river continuity assessment focused on roadstream crossings. The Winnicut River is the site of a restoration project that removed a head-of-tide dam and resulted in the only free-flowing major tributary to the Great Bay Estuary. The river system currently supports a small annual run of river herring, and with the removal of the dam and ladder system, migratory fish will now have access to a total of 37 miles of potential upstream habitat. In anticipation of improved access, The Nature Conservancy conducted a fish passage assessment for all stream crossings above the head-of-tide dam. We used an assessment methodology based on the Massachusetts Riverways Program, with adjustments following a similar crossing study in the Ashuelot River system (NH). We assessed a total of 42 road crossings in the Winnicut watershed, and classified them as severe, moderate, minor, or passable for fish passage. One crossing was identified as severe, thirty-five were moderate, six were minor, and no crossings were determined to be fully passable for all fish. To develop a priority list of crossings for improvements, we focused on culverts with moderate or severe barrier rankings and screened out crossings associated with major highway infrastructure. We then used GIS analysis to determine the habitat potential upstream of each crossing, and prioritized crossings with greater than 0.5 miles of upstream habitat. We ordered priority crossings from nearest to furthest from the dam site at the river mouth. Our analysis produced a final list of 11 crossings that, if all were improved, would reestablish 19.5 miles of unfragmented habitat for migratory fish. We are sharing results of this study with local and state officials in hopes of securing funds and making structural enhancements to priority road crossings. Going forward, we hope that this information will lead to increases in migratory fish populations in the Winnicut River and throughout the entire Great Bay Estuary

An Innovative Technique for Water Leak Detection Stemming from Radio Astronomy : A Potential University Technology Transfer

There have been many documented cases of technology transfer from astronomy to other disciplines such as medicine, for example, a system for diagnosing breast cancer utilising software originally developed to mosaic planetary images. The approach taken in this research will involve using a technology originally developed for radio astronomy to detect water leaks in pipes that are part of water networks in various infrastructure systems. This is innovative research as it involves an interdisciplinary approach to explore a technology and evaluate its commercial potential. Experiments are underway in which signals from an acoustic phased array are amplified and digitized using a multichannel analogue-to-digital (ADC) converter and analysed using a software correlation technique to identify leak signatures. Therefore, the chosen technology’s commercialisibility will be tested for alternate applications which can be applied to infrastructures such as water networks. In addition, the importance of interdisciplinary research will also be reflected through this research

Fatigue of glass reinforced plastic pipes and joints for offshore applications

PhD ThesisIn this thesis the static and fatigue characteristics of glass filament wound plastic pipes and joints are examined by experiments and numerical analysis. A hydraulic fatigue test rig, capable of exerting static or cyclic pressures of up to 70 MPa, was designed and built to enable pressure tests to be carried out on glass reinforced epoxy and glass reinforced vinyl ester composite pipes incorporating various joints. Static weepage and burst tests were performed on tubular specimens with and without rubber liners to determine their weepage and burst strengths under internal hydraulic pressure and to investigate the influence of the joints. Fatigue weepage tests were performed to determine the fatigue life and failure modes of glass fibre/epoxy and glass fibre/vinyl ester pipes and joints. For each material system, three types of specimen were tested. These were plain pipes, pipes with coupler-bonded joints (or laminate joints in the case of vinyl ester resin based pipes) and pipes with spigot/socket bonded joints. All specimens were commercial products with nominal diameters of two inches (50 mm). A family of curves showing pressure versus life was obtained. It was observed that weepage mostly occurred close to the pipe joints when pipes were subjected to internal pressure. Optical microscopy was used to investigate the damage initiation and propagation mechanisms in the specimens after testing. Finally, two-dimensional and three-dimensional finite element analyses were carried out to calculate the stress and strain distributions, to predict the strength, to interpret the experimental results and to examine the failure modes of the specimens. Ply-by-ply stress analysis and the Tsai-Wu failure criterion were employed for the strength prediction.British Gas plc, Engineering Research Station