Image analysis of soil failure on defective underground pipe due to cyclic water supply and drainage using X-ray CT

Abstract

The ground subsidence on the underground pipe often is caused with the reduction of the effective stress and the loss of suction in the base course and then, soil drainage into the pipe. The final formation of the cavity growth in the ground was observed as the ground subsidence. Authors focused this problem and hence performed model tests with water-inflow and drainage cycle in the model ground. The mechanism of cavity generation in the model ground was observed using an X-ray Computed Tomography (CT) scanner. In those studies, water was supplied into the model grounds from the defected underground pipe model in case of the change of relative density and grain size distribution. As results, it was observed that the loosening area was generated from the defected part with water-inflow and some of the soil particles in the ground were drained into the underground pipe through the defected part. And afterward, the cavity was generated just above the defected part of the model pipe in the ground. Based on this observation, it might be said that the bulk density of soil around the defected pipe played one of key factor to generate the cavity in the ground. Moreover, the dimension of the defected part should be related to the magnification of the ground subsidence, in particular, crack width on a sewerage pipe and particle size would be the quantitative factor to evaluate the magnification of the ground subsidence. ƒIn this paper, it was concluded that the low relative density of soil would become the critical factor to cause the fatal failure of model ground if the maximum grain size was close to the dimension of crack width of defective part. The fatal collapse of the ground with high relative density more than 80% would be avoided in a few cycles of water inflow and soil drainage.

Keywords

relative density / grain property / model test / road subsidence / underground pipe / image processing / X-ray CT

References

[1] DelleurJ W. Sewerage Failure, Diagnosis and Rehabilitation. In: MacaitisW A, ed. Urban Drainage Rehabilitation Programs and Techniques, Selected papers on urban drainage rehabilitation from 1988-1993. New York: ASCE, 1994, 11-28

[2] Davis J P, Clarke B A, Whiter J T, et al. Factors influencing the structural deterioration and collapse of rigid sewer pipes. Urban Water, 2001, 3(1-2): 73-89

[3] Makropoulos C K, Butler D. Distributed water infrastructure for sustainable communities. Water Resources Management, 2010, 24(11): 2795-2816

[4] Tohda J, Yoshimura H. A new design method for buried pipes. In: Proceedings of the 16th ICSMGE. 2005, 1319-1322

[5] Tohda J, Hachiya M. Response and design of buried pipelines subjected to differential ground settlement. In: Proceedings of the 16th ICSMGE. 2005, 1659-1662

[6] Kuwano R. Horii T, Kohashi H. Evaluation of loose ground surrounding a cavity due to the outflow of soil. In: Proceedings of the 41st Annual Japan Geotechnical Society (JGS) conference. 2006, 1785-1786 (in Japanese)

[7] Mukunoki T, Otani J, Nonaka S, et al. Evaluation of cavity generation in soils subjected to sewerage defects using X-ray CT. In: Proceedings of International Workshop GeoX2006, Advances in X-ray Tomography for Geomaterials. 2006, 365-371

[8] Public Works Research Institute. Investigation of Cavity Generation in the Ground Around a Underground Model. Annual Report of PWRI. 2006 (in Japanese).

[9] Mukunoki T, Otani J, Kuwano R. Visualization of cavity generation in soils on sewerage defects using X-ray CT. In: Proceedings of the 13th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering. 2007, 1: 485-488

[10] Mukunoki T, Kumano N, Otani J, et al. Visualization of three dimensional failure in sand due to water inflow and soil drainage from defected underground pipe using X-ray CT. Soil and Foundation, 2009, 49(6): 959-968

[11] Mukunoki T, Kumano N, Otani J. Failure of sands with different density on defected pipe in X-ray CT images. In: Proceedings of the 14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering. 2011 (in print).

[12] Wang M C, Hsieh C W. Collapse load of strip footing above circular void. Journal of Geotechnical Engineering, 1987, 113(5): 511-515

[13] National institute for land and infrastructure management (NILIM), ministry of land, infrastructure and transport, Japan. Annual Report of Waste Water Management and Water Quality Control. 2006 (in Japanese)

[14] Reynolds J H, Barrett M H. A review of the effect of sewer leakage on groundwater quality. Water and Environment Journal, 2003, 17(1): 34-39

[15] AASHTO HDG. Highway Drainage Guidelines. volumes I-XIII, 3rd edition and volume XIV, Culvert inspection, material selection and rehabilitation, 2006

[16] Ketcham R A, Carlson W D. Acquisition, optimization and interpretation of X-ray computed tomographic imagery: application to geoscience. Computers & Geosciences, 2001, 27(4): 381-400

[17] Otani J, Mukunoki T, Obara Y. Application of X-ray CT method for characterization of failure in soils. Soil and Foundation, 2000, 40(2): 111-120

[18] Otani J, Mukunoki T, Sugawara K. Evaluation of Particle Crushing in SoilsUsing X-Ray CT Data. Soil and Foundation, 2005, 45(1): 99-108

Acknowledgment

Authors thank to Mr. Takebayashi, T. and Mr. Koujimaru, N., who were the former students of the master degree belonged to the graduate school of science and technology at Kumamoto University for their contribution to this study.

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg