Geosynthetic reinforcement for the reduction of the effects of explosions of internally pressurised buried pipes

https://doi.org/10.1016/j.geotexmem.2006.07.001Get rights and content

Abstract

Soil reinforcement is a well-established technique for works such as embankments, steep slopes and walls. This paper presents the results of a study on an innovative use of geosynthetic reinforcement for the protection of buried pressurised pipes. The collapse of a pipe inside reinforced and unreinforced sand was simulated in models studies in the laboratory using a large rigid steel tank. Different configurations and types of geosynthetics were tested including woven geotextiles, a geogrid and a metallic reinforcement. The scale of the models in the laboratory was 1:4 and the series of tests involved the simulation of two types of pipe collapse. The first one consisted of a continuous expansion of a cylindrical cavity until failure of the soil mass was achieved and the second consisted of air burst through a longitudinal crack in the pipe. The results obtained showed a significant influence of the presence of the reinforcement on the pressure resisted by the embankment and in reducing the consequences of pipe collapse, depending on reinforcement type and arrangement. The potential use of reinforced embankments to protect pressurised pipes has also been demonstrated.

Introduction

Soil reinforcement has been used for over 30 years to improve the mechanical properties of geotechnical engineering works such as embankments on soft soils, steep slopes and walls. During these years, geosynthetics materials have strengthen their reputation as reliable reinforcing elements based on improved material characteristics and design practices. A potential use of geosynthetic materials such as geotextiles and geogrids is to reinforce embankments containing buried pressurised pipes. Selvadurai (1989) studied the use of geogrids for the enhancement of the uplift capacity of buried pipelines. However, the authors of the present work are not aware of any study on the use of geosynthetic for the minimisation of accidents involving buried pressurised pipes.

Many accidents involving pipelines or pressurised pipes are reported in the literature (Manfredi and Otegui, 2002; NTSB, 2000, NTSB, 2001, NTSB, 2003; Kinsman and Lewis, 2000 and Bjerketvedt et al., 1997, for instance). Fig. 1(a)–(c) shows some examples of severe damages dues to pipe explosions. Fig. 1(a) shows the consequences of the explosion of a 25 mm diameter gas pipe in the city of St. Cloud, Minnesota, USA (NTSB, 2000). The leakage of gas and subsequent explosion were caused by damage to the pipe during the installation of a utility pole support anchor in the sidewalk. As a result, 4 persons were fatally injured, 1 person was seriously injured and 10 persons received minor injuries. Six buildings were destroyed. Fig. 1(b) presents part of the material damages caused by the explosion of a 750 mm diameter segment of a gas pipeline in Carlsbad, New Mexico, USA (NTSB, 2000). Twelve persons who were camping under a concrete-decked steel bridge that supported the pipeline across the river were killed and their three vehicles destroyed. Two nearby steel suspension bridges for gas pipelines crossing the river were extensively damaged. Property and other damages or losses totalled almost one million dollars. Fig. 1(c) shows the consequences of a pipe explosion in an industrial area in Belgium, 2004, where 15 people died and approximately 200 were injured (Irish Examiner, 2004; Rossiqnel, 2004).

As the number and dimensions of pressurised pipes increase, so does the possibility of a greater number of accidents or leakages, which can cause losses of human lives, material losses or environmental damages. These accidents are particularly important when the pipes are located inside or close to urban areas or in industrial plants (Fig. 1). During the last decade there has been a marked increase in the use of pipelines for gas transportation in Latin American countries, particularly in Brazil, which highlights the importance of the protection for such structures as well as those close to it.

In accidents with pipes conducting flammable gases most of the damages and casualties are commonly a result of gas combustion. Gas ignition does not necessarily occur at the moment of pipe failure and it may take several minutes of gas leakage until some mechanism produces ignition and explosion occurs, as can be observed in several accidents reported in Kinsman and Lewis (2000). The collapse of a buried pipe associated with gas combustion is certainly a much more complex phenomenon than that of a pipe conducting a non-flammable gas or liquid.

Different types of failures can take place in pressurised pipes. These failures can be localised in weak points or sections of the pipe, in joints, in corroded regions or develop along large portions of the pipe length. Some experimental and theoretical studies on failure mechanisms in pressurised confined and unconfined pipes and pipelines can be found in the literature (Thomas and Oakley, 1998; Beltman and Shepherd, 1998 and Lam and Zielonka, 2002, for instance). Fig. 2 shows some typical failure mechanisms in pressurised pipes (NTSB, 2001; Manfredi and Otegui, 2002).

Geosynthetic layers installed during pipe placement in trenches or embankments can minimise or avoid serious consequences of pipe failures and explosions. Fig. 3(a)–(c) shows schematically how geosynthetic reinforcement can contribute to minimise the consequences of pipe collapse. Fig. 3(a) and (b) shows installation of geosynthetic layers to minimise the damages to pressurised pipes due to the action of perforating objects (an excavator bucket tooth, for instance) or unexpected surface surcharges. Fig. 3(c) shows reinforcement arrangements to minimise the effects of pipe explosion of leakages. The presence of the reinforcement may also minimise actions of vandalism.

This work presents part of a research programme to study the use of the soil-reinforcement technique to protect pressurised pipes and to minimise the consequences of collapse of such pipes. Model tests were carried out under controlled laboratory conditions to investigate cavity expansion in a reinforced soil mass and the consequences of pipe collapse, with particular emphasis to the use of geosynthetic reinforcement.

Section snippets

Experiments

The explosion of a pressurised buried pipe is a very complex phenomenon to be modelled. Thus, the research programme in progress to study the application of geosynthetic reinforcement to minimise the effects of the collapse of buried pressurised pipes involves tests in the laboratory and in the field as well as numerical simulations of this type of problem. The first stage of the research programme described here involved the investigation of two types of pipe collapse mechanisms. The first one

Pipe in a ground with horizontal surface

Fig. 6 presents the variation of the pressure transferred to the soil mass versus cavity volume increase for different values of cavity depth and horizontal ground surface in unreinforced tests. Cavity volume increase was quantified in terms of the percentage of cavity volume increase with respect to its initial volume. As expected, the results show that the maximum pressure resisted by the surrounding soil increases with cavity depth. Post-peak behaviour is dependent on cavity depth. Softening

Conclusions

This paper presented a laboratory study on the use of geosynthetic reinforcement to minimise the consequences of the collapse of buried pressurised pipes. Different ground geometries and types and arrangements of reinforcements were tested. The main conclusions of this study are summarised below.

Geosynthetic reinforcement can efficiently strengthen the soil in case of collapse of a buried pressurised pipe and minimise its consequences for neighbour structures or people. The greater the

Acknowledgements

The authors are indebted to the following institution that supported the research activities described in this work: University of Brasilia (Brasilia, Brazil), University of San Agustin (Arequipa, Peru), CAPES-Brazilian Ministry of Education and CNPq-Brazilian Research Council (CTPetro Research Programme).

References (25)

  • Test Method for Tensile Properties of Geotextiles by the Wide-width Strip Method—ASTM D 4595. ASTM Standards on Geosynthetics

    (1995)
  • Beltman, W.M., Shepherd, J.E., 1998. Structural response of shells to detonation and shock loading—Parts I and II....
  • D. Bjerketvedt et al.
    (1997)
  • Bolton, M.D., Barefoot, A.J., 1997. The variation of critical pipeline trench back-fill properties. In: IBC Conference...
  • Gomes, R.C., 1992. Tensile tests on fabrics and plastic materials. Research Report No. 004A/92, Graduate Programme of...
  • Irish Examiner, 2004. Belgium Gas Pipe Explosion Kills 15. In...
  • Kinsman, P., Lewis, J., 2000. Report on a study of international pipeline accidents. Mechphyic Scientific Consultants,...
  • Lam, A., Zielonka, M., 2002. Fracture response of externally flawed thin-walled plastic tubes to gaseous detonation...
  • C. Manfredi et al.
    (2002)
  • NTSB, 2000. Natural gas pipeline rupture and subsequent explosion in St. Cloud, Minnesota, December 11, 1998. Pipeline...
  • NTSB, 2001. Natural gas explosion and fire in south riding, Virginia July 7, 1998. Pipeline Accident Report,...
  • NTSB, 2003. Natural gas pipeline rupture and fire near Carlsbad, New Mexico, August 19, 2000. Pipeline Accident Report...
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