Soil-pipe-atmosphere interaction under field conditions
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TRANSPORT ENGINEERING GEOLOGY
Soil-pipe-atmosphere interaction under field conditions Ramy Saadeldin 1 & Yafei Hu 2 & Amr Henni 3 Received: 2 January 2019 / Accepted: 9 October 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Unsaturated clay deposits swell and shrink as a result of seasonal variations in climatic conditions and affect the performance of underground infrastructure systems. This paper investigates the response of a 150-mm PVC pipe buried in a highly plastic clay deposit under field conditions. A numerical model was established to integrate the daily climatic conditions. To accurately model field performance, the developed numerical model incorporated the use of a bimodal soil water characteristic curve (SWCC) and the simulation of the hydraulic characteristics of a cracked soil structure. The model results showed that the response of both the soil and the pipe was influenced by soil properties (native and backfill), the depth below the ground surface, and most importantly, the surface boundary condition (sealed versus unsealed surface). Although the pipe trench was covered by a pavement structure, the backfill material consisting of granular materials (i.e., mixed concrete) showed a noticeable variation in volumetric water content (VWC) with time. It was also observed that the effects of the atmosphere extended below the pipe burial depth to a depth of 4 m in the clay soil surrounding the trench. While the pipe trench was backfilled with a non-expansive material, the pipe experienced fluctuating displacements throughout the year. Finally, the model was utilized to give insight into the actual flux transferred through the pavement structure to the backfill material surrounding the pipe. It was predicted that approximately 30% of the surface net flux permeated the pavement structure and interacted with the underlying backfill materials. Keywords Climatic conditions . Soil movements . Soil temperature . Unsaturated soils . Pavement structure . Soil cracks
Introduction Unsaturated soils experience wetting and drying cycles due to seasonal climate changes, park watering, or any substantial water leakage. These changes produce variations in soil moisture content, which in response causes considerable soil swell/shrink movements. Pipes buried below the ground surface may be subjected to severe stresses or even failures as a consequence of soil movements. Various researchers reported that seasonal climate changes are a contributing factor to the failures of shallow
* Ramy Saadeldin [email protected] 1
University of British Columbia, Okanagan Campus, Kelowna, BC V1V 1V7, Canada
2
City of Regina, Regina S4P 3C8, Saskatchewan, Canada
3
Faculty of Engineering and Applied Science, University of Regina, 3737 Wascana Pkwy, Regina, SK S4S 0A2, Canada
buried pipelines (Clark 1971; Gould 2011; Hu and Vu 2011; Hudak et al. 1998; Morris 1967; Rajeev et al. 2012). The field behavior of soil deposits is dependent on the local geo-environmental conditions (e.g., the mineral c
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