Computational Seismic Fracture Synthesis of Tidal Barrage using Enhanced Isotropic Plasticity Damage Mechanics and Coupled Lagrangian-Eulerian Multiphase Interaction

Abstract

Mega-engineered hydraulic structures like dams and barrages are critically sensitive to strong ground motion if constructed within the vicinity of triggered fault lines. Collapse post excessive deformation leads to severe environmental impact. In this study, fracture corresponding to the response of a concrete tidal barrage to strong ground motion is analyzed along with behavioral effects due to reservoir-barrage dynamic interaction. An enhanced version of the plasticity damage mechanical model, which includes effects due to degradation of elastic stiffness of concrete as well as restoration of fracture energy losses is assigned as material behavior. The fluid-structure interaction is solved using an idealized Lagrangian-Eulerian formulation. The proposed improvised numerical formulations are validated against benchmark simulations performed on the Koyna dam situated in Maharashtra, India and the results captured are upto 94% accurate. Finite element simulation of a tidal barrage is performed using a computationally stable mesh with global grid to length ratio of 4.2. The yield surface captured is elliptical in nature and fracture is observed to be propagating from bottom of gate housing covering upto four nodal integration points.

Figures (15)

• Figure 1: A coastal outline of Gujarat showing traces of historic love waves originating from strong ground motions recorded at stations named GIRNAR, NASW, BARW, ALIR, KEWA with one of he historic path tracing back from station GIRNAR to ALIR passes diagonally through the bottom tectonics of the Kalpasar dam.
• Figure 2: A typical stress-strain curve of a quasi-brittle material under uni-axial tension from split-tensile test comparing Reinhardt1986aand Hillerborg1985 interpolation of the tension softening region.
• Figure 3: Yield surface and crack insertion zone of a enriched tetrahedral element. (a) shows the propagation of elliptical crack from the initial yield plane to an enriched non-planar yield plane. (b) shows the uniaxial hyperbolic fit of polygonal Mohr-Coulomb and elliptical Drucker-Pager yield profile.
• Figure 4: Scattered line plot showing the variation of tensile cracking stress($\delta \left( \Im \right)_{tens}^{^{cracking,h}}$) with the tensile crack propagation displacement ($\delta \left( \Im \right)_{tens}^{^{cracking,h}}$), taking into consideration the subsequent tensile strain softening points.
• Figure 5: A meshed two dimensional model of barrage highlighting the coupled interaction between the Eulerian-Lagrangian reservoir domain with the structural barrage domain along with velocity induced free water surface sloshing.