Ice Stresses in Reservoirs: Effect of Water Level Fluctuations

Stander, Edward

doi:10.1061/(asce)0887-381x(2006)20:2(52)

Cited by 21 publications

(13 citation statements)

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“…The reservoir shape can cause a spatial variability of thermal strains. Moreover, the ice cover bending and buckling due to the rise/fall of water stage inevitably creates additional surface strains (Stander 2006). The time series of the distance P0Pi were observed and recorded by the LRF.…”

Section: What Is the Residual Strain ɛR?mentioning

confidence: 99%

“…The normal stresses were always lower than the thermal ones, especially they were lower by more than 250 kPa (~35%) during the warm spells, indicating the residual strains created a considerable relief to the thermal loads normal to the dam face. This argued that a significant error can be produced by the ignorance of environmental responses to thermal loads; for instance, ignorance of ice dynamics on the dam face, the development and evolution of cracks, the changes in water level (Stander 2006;Taras et al 2009), and wind stresses (Prinsenberg et al 1997). The stresses parallel with the nearest dam face kept even equal to the thermal stresses except during the temperature phase (b), when the parallel stresses became larger than thermal ones.…”

Section: Estimate Of Surface Ice Stressmentioning

confidence: 99%

“…Previous findings have revealed that the ice pressure in reservoirs can arise from various processes that can act alone or in combination. Among these processes, one can identify thermal forces (Cox 1984;Ko et al 1994;Comfort et al 2003), forces associated with changes in water level (Stander 2006;Taras et al 2009) and wind forces (Prinsenberg et al 1997). Furthermore, in situ data and theoretical analyses also indicate that the magnitude of thermal ice load is affected by the snow/slush cover, ice thickness, shoreline confinement, reservoir shape, and relative stiffness of various hydraulic structures (Boulton and Jones 1979;Comfort et al 2000b,c;Arunachalam 2005;Petrich et al 2015).…”

Section: Introductionmentioning

confidence: 99%

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Residual Strain in a Reservoir Ice Cover: Field Investigations, Causes, and Its Role in Estimating Ice Stress

Huang

Leppäranta

et al. 2018

J. Hydraul. Eng.

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Ice strain dominates the ice thrust and dynamics on reservoir dams and retaining structures. An exclusively designed laser range finder was deployed to measure the surface ice displacements along six directions at a reservoir in northeastern China. The incompletely confined boundary (ice-boundary bonding), ice cracks development, water level fluctuations, parallel crack dynamics, and ice creep allow the surface ice to move rather than keep still in response to thermal deformation/pressure, and thus cause the ice strain deviates from thermal strain. Consequently, a residual strain was introduced and calculated from the recorded displacements. Observations showed that the residual strains were anisotropic and showed diurnal patterns following the air/ice temperature. A scale-dependence of crack development was observed and causes potential scale-effects to residual strains. The real ice strain consists of thermal strain and residual strain. The proportion of the latter increased as time went by. A modified constitutive law accommodating the residual strains was developed to evaluate the impacts of the residual strains and to estimate the surface ice stresses. Modeling results underlined the role of the residual strain in determining both the principal stress and the stress perpendicular to and parallel with the dam face. The residual strain is probably the reason why the observed ice stress is always much lower than the single thermal stress.

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Section: What Is the Residual Strain ɛR?mentioning

confidence: 99%

Section: Estimate Of Surface Ice Stressmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Residual Strain in a Reservoir Ice Cover: Field Investigations, Causes, and Its Role in Estimating Ice Stress

Huang

Leppäranta

et al. 2018

J. Hydraul. Eng.

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“…Different theories are proposed to explain this finding (e.g. tidal jacking ;Stander 2006) but increases due to the changes in material properties of columnar ice under lateral confinement may be another and this effect is explored in this paper.…”

Section: Introductionmentioning

confidence: 96%

Numerical studies for a better understanding of static ice loads on dams

et al. 2018

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It is important to anticipate potential maximum ice loads to ensure the structural stability of dams in cold climates. Finite element modeling (FEM) can provide some insights into process mechanisms. Four important ice-loading events on dams are presented and simulated. The measured loads were caused by the thermal expansion of ice together with intermediate water level fluctuations. Only the thermal expansion is modeled by the FEM, but the impact of water level fluctuations can increase lateral confinement that increases the predicted load by 36% to 106%, particularly when the cover contains mostly columnar ice. It is demonstrated that the presence of snow ice in the cover can decrease the predicted load by 35% to 53%. The study also demonstrates how initial stresses in the ice can affect the ultimate load and show that the very-difficult-to-manage delayed-elastic strain term need not be included in the material model where preliminary results suffice.

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“…Nevertheless, such tests are limited by poor real-time performance and large deviations from the actual ice conditions. Numerical methods calculate the static ice pressure by establishing the boundary conditions of object body (Xu, 1985;Huang et al, 2005;Stander, 2006;Paavilainen and Tuhkuri, 2013); however, the uncertainties and complexity of boundary conditions limit their applicability. Therefore, it is diffi cult to fi nd the appropriate equations.…”

Section: Introductionmentioning

confidence: 99%

A bellow pressure fiber optic sensor for static ice pressure measurements

2015

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Static ice pressure affects safe operation of hydraulic structures. However, current detection methods are hindered by the following limitations: poor real-time performance and errors owing to the partial pressure of the surrounding wall on traditional electrical resistance strain bellow pressure sensors. We developed a fi ber optic sensor with a special pressure bellow to monitor the static ice pressure on hydraulic structures and used the sensor to measure static pressure in laboratory ice growth and melting tests from −30°C to 5°C. The sensor resolution is 0.02 kPa and its sensitivity is 2.74 × 10 −4 /kPa. The experiments suggest that the static ice pressure peaks twice during ice growth and melting. The fi rst peak appears when the ice temperature drops to −15°C owing to the liquid water to solid ice transition. The second peak appears at 0°C owing to the thermal expansion of the ice during ice melting. The novel fi ber optic sensor exhibits stable performance, high resolution, and high sensitivity and it can be used to monitor the static ice pressure during ice growth and melting.

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Ice Stresses in Reservoirs: Effect of Water Level Fluctuations

Cited by 21 publications

References 0 publications

Residual Strain in a Reservoir Ice Cover: Field Investigations, Causes, and Its Role in Estimating Ice Stress

Residual Strain in a Reservoir Ice Cover: Field Investigations, Causes, and Its Role in Estimating Ice Stress

Numerical studies for a better understanding of static ice loads on dams

A bellow pressure fiber optic sensor for static ice pressure measurements

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