Theory and application of ice thermodynamics and mechanics for the natural sinking of gabion mattresses on a floating ice cover

Abstract

To establish an evaluation method based on ice thermodynamics and ice mechanics to predict ice cover failure to ensure construction safety, field tests were carried out in the Shisifenzi Bend of Yellow River during the winter of 2020–2021. Data such as meteorological, vertical ice deflection, radar detection of long-term ice thickness, and single point ice thickness by drilling ice hole were collected or measured. Based on the data and previous results of ice thermodynamics and mechanics, the ice-water interface heat flux of 9.06 W/m2 and a bearing capacity attenuation coefficient of 0.072 under long-term ice load were obtained. A new equation including ice thickness, ice temperature, and attenuation time was estimated to evaluate ice bearing capacity in Ningxia-Inner Mongolia reach of Yellow River. Besides, the safety boundary condition of ice thickness for construction at different air temperatures and attenuation times (24 h, 48 h, 72 h, 96 h, and 120 h) was calculated. Under the condition that the engineering task is not urgent, it was recommended to choose an attenuation time of 120 h. Moreover, it was recommended that the ice thickness for safe construction should be increased by 10% for slightly defective ice cover containing air bubbles, sediment, and small cracks, and by 40% for severely defective ice cover with cracks exceeding 50% of the ice thickness or with water flowing in the cracks. In addition, some measures such as increasing ice thickness and thinning the thickness of gabions and the potential limitations of the ice mechanics equations are analyzed and discussed for future applications.