Protection of flexible pipes from dynamic surface stresses by geocell-reinforced sand backfill

Document Type : Research Paper

Authors

1 Building and Construction Engineering Department, University of Technology, Baghdad, Iraq

2 Civil Engineering Department, University of Karbala, Karbala, Iraq

Abstract

Underground conduits or utility pipelines are buried at shallow depths in trenches with the help of flowable fills. These pipes are subjected to deformations and damage due to application of dynamic traffic loads or heavy static loads from the vehicles. This study presents the results of a pipe model installed in geocell reinforced and unreinforced sand. A PVC pipe of 110 mm diameter and 1.4 mm wall thickness was installed in a rigid tank to simulate buried pipe. Different types of instrumentation such as earth pressure cell and vibration meter were used to measure the vertical transmitted pressure and displacement amplitude on the pipe crown, respectively. Different factors that affect the performance of pipes installed in sand bedding and backfill were investigated. The factors included state of compaction of bedding and backfill, magnitude of the applied surface dynamic pressure, and the load frequency. The results of this study were presented in terms of the vertical transmitted pressure on the crown of the pipe, surface soil settlement, the displacement amplitude of the pipe crown. It was concluded that the performance of the buried pipe depends on the state of compaction of sand bedding and backfill. When the relative density of the sand increases from 30% to 60%, the vertical pressure on the pipe crown, surface settlement, and the amplitude of displacement, decrease by about 30 %, 40 % and 15 %, respectively. When the relative density of the soil increases from 30% to 60%, more than 40% reduction was recorded in the surface settlement for unreinforced model while this reduction is about 25% for model reinforced with geocell.

Keywords

Main Subjects

References

  • Arockiasamy, M., Chaallal, O., Limpeteeparakarn, T. (2006), "Full-Scale Field Tests on Flexible Pipes under Live Load Application". J. Perform. Constr. Facil, Vol. (1), No. (20), pp. 21-27.
  • American Society of Testing and Materials (ASTM) (2006). "Standard Test Method for Specific Gravity of Soil Solids by Water Pycnometer" ASTM D854, West Conshohocken, Pennsylvania, USA.
  • American Society of Testing and Materials (ASTM) (2006). "Standard Test Method for Particle Size-Analysis of Soils" ASTM D422-02 (2002), West Conshohocken, Pennsylvania, USA.
  • American Society of Testing and Materials (ASTM) (2006). "Standard Test Method for Maximum Index Density and Unit Weight of Soils Using a Vibratory Table" ASTM D4253-00 (2006), West Conshohocken, Pennsylvania, USA.
  • American Society of Testing and Materials (ASTM) (2006). "Standard Test Method for Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density" ASTM D4254-00 (2006), West Conshohocken, Pennsylvania, USA.
  • American Society of Testing and Materials (ASTM) (2006). "Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions" ASTM D3080, West Conshohocken, Pennsylvania, USA.
  • American Society of Testing and Materials (ASTM) (2006). "Standard Test Method for Classification of Soils for Engineering Purposes (Unified Soil Classification System)" ASTM D2487-06, West Conshohocken, Pennsylvania, USA.
  • Brachman, R.W.I., Moor, I.D., Rowe, R.K., (2000). "The Design of a Laboratory Facility for Evaluating the Structural Response of Small Diameter Buried Pipe", Canadian Geotechnical Journal. Vol. (37), No. (2), pp. 281-295.
  • Dash, S.K., Krishnaswamy, N.R., Rajagopal, K., (2001), "Bearing Capacity of Strip Footings Supported on Geocell Reinforced Sand", Geotextiles and Geomembranes, No. 19, pp. 235-256.
  • Dash, S.K., Sireesh, S., Sitharam, T.G., (2003). "Model Studies on Circular Footing Supported on Geocell Reinforced Sand underlain by Soft Clay". Geotextile and Geomembranes, Vol. 21, No. 4, pp. 197-219.
  • Fattah, M. Y., Zbar, B. S., Al-Kalali, H. H. M., (2015), "Experimental Study on the Effect of Embedment Depth of Buried Flexible Pipe Subjected to Static Load", Global Journal of Engineering Science and Research Management, Vol. 2, No. 12, December, pp. 113-122.
  • Fattah, M. Y., and Mohammed Redha, W. B., (2016), "Effect of Geocell Reinforcement in the Mitigation of Traffic Loads Transmitted to the Flexible Buried Pipes", Global Journal of Engineering Science and Research Management, Vol. 3, No. (7), July, pp. 118-128.
  • Fattah, M. Y., Hassan, W. H., Rasheed, S. E., (2018a), "Effect of Geocell Reinforcement above Buried Pipes on Surface Settlement", International Review of Civil Engineering (I.RE.C.E.), Vol. 9, N. 2, pp. 86-90.
  • Fattah, M. Y., Hassan, W. H., Rasheed, S. E., (2018b), "Behavior of Flexible Buried Pipes Under Geocell Reinforced Subbase Subjected to Repeated Loading", International Journal of Geotechnical Earthquake Engineering, Vol. 9, Issue 1, pp. 22-41, doi:10.4018/IJGEE.2018010102.
  • Hassan, W. H., Fattah, M. Y., Rasheed, S. E., (2018), "Numerical Analysis of the Effect of Geocell Reinforcement above Buried Pipes on Surface Settlement and Vertical Pressure", Engineering and Technology International Journal of Geotechnical and Geological Engineering, Vol. 12, No. 3, pp. 221-227, World Academy of Science, International Scholarly and Scientific Research & Innovation.
  • Hegde, A., Kadabinakatti, S. and Sitharam, T.G., (2014). “Protection of Buried Pipelines Using a Combination of Geocell and Geogrid Reinforcement: Experimental Studies. In-Ground Improvement and Geosynthetics, pp. 289-298.
  • Marto, A., Oghabi, M. and Eisazadeh, A., (2013). “Effect of Geocell Reinforcement in Sand and its Effect on the Bearing Capacity with Experimental Test; A review”. Electronic Journal of Geotechnical Engineering, 18, pp. 3501-3016.
  • Masada, T. and Sargand, M., (2007), "Peaking Deflections of Flexible Pipe During Initial Backfilling Process", Journal of Transportation Engineering, Vol. (2), No. (133), pp. 105–111.
  • Moghaddas Tafreshi, S. N., Khalaj, O. (2008), "Laboratory Tests of Small-Diameter HDPE Pipes Buried in Reinforced Sand under Repeated Load", Geotextiles and Geomembranes, Vol. (2), No. (26), pp. 145-163.
  • Watkins R., Brent K., Rich M., and Shah R., (2010), "Pipe Zone Bedding and Backfill:
    a Flexible Pipe Perspective", Proceedings of the 2010 Pipeline Division Specialty Congress, ASCE, Keystone, Colorado, USA, pp. 426–438
International Journal of Mining and Geo-Engineering
Volume 56, Issue 1
March 2022
Pages 61-66

Files

Share

How to cite

Statistics