Finite element analysis for identifying locations of cracking and hydraulic fracturing in homogeneous earthen dams

Priyanka Talukdar,Arindam Dey

doi:10.1186/s40703-020-00139-8

Priyanka Talukdar, Arindam Dey

Open Access

https://doi.org/10.1186/s40703-020-00139-8

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Abstract

This paper reports a finite element study to identify the locations of crack initiation in a homogeneous earthen dam at its post-construction and reservoir operation stages. The steady state and transient analyses, including reservoir rise-up and drawdown conditions, are simulated to identify the favorable conditions and locations of crack generation. The behavioral response of the dam is represented in terms of the developed total stress, horizontal deformations of the faces, strain accumulation in the dam, and the differential settlement of the dam base. The locations of post-construction cracks are identified based on the negative minor principal stresses developed on the dam faces. For both single-lift and multiple-lift modeling techniques, the upstream face of the dam is found to be the most favorable location for the crack generation. For transient reservoir operations (rise-up and drawdown scenarios), it is identified that hydraulic fracturing may occur on either faces of the dam at specific heights, governed by the minor principal stresses becoming lesser than the developed pore-water pressure. Depending on whether the reservoir drawdown occurs before or after the attainment of steady-state phreatic level within the body of the dam, the pore-water pressure distribution within the dam are found notably different. This results in hydraulic fracturing occurring at different faces of the dam and at different heights. It is important to have a thorough understanding of the tentative location of the cracks developed in homogeneous earthen dams so that proper mitigation measure can be adopted as per requirement.

Highlights

The detrimental effects of cracks on earthen dams and embankments was first observed by Casagrande [1], wherein the importance of dam safety, even with the occurrence of cracks, was highlighted
The paper presents the response of homogeneous earthen dam subjected to cracking and hydraulic fracturing
Finite element based seepage analysis and stress analysis are conducted to decipher the responses of the homogeneous earthen dam under various conditions

Summary

Introduction

The detrimental effects of cracks on earthen dams and embankments was first observed by Casagrande [1], wherein the importance of dam safety, even with the occurrence of cracks, was highlighted. Based on saturated–unsaturated material models for the earthen material, various analyses were conducted, which included the steady-state analyses for the post-construction cracking and transient analyses for incorporating the reservoir drawdown and rise-up conditions to identify hydraulic fracturing.

Results

Conclusion