基于近场动力学均匀化的混凝土防渗墙等效损伤模型

An Equivalent Damage Model of Concrete Cut-Off Wall Based on Homogenization of Peridynamics

摘要:

混凝土防渗墙在我国覆盖层高土石坝坝基防渗中应用非常广泛。受到巨大水推力、土压力及不均匀沉降作用的混凝土防渗墙可能会出现局部破损，该过程涉及到的尺度差异大、复杂破损精细化描述等问题通常是分析的难点。通过近场动力学多尺度均匀化分析，提出了一种高土石坝混凝土防渗墙破损等效损伤模型。首先给出了该等效损伤模型建立的基本思路，然后基于防渗墙破损的机理和应力状态规律的认识，采用近场动力学多尺度均匀化方法，建立了可用于工程三维分析的高土石坝防渗墙破损的等效损伤模型。该模型具有形式简单、参数少且物理意义明确、拉压统一描述、模型新引入的指数参数可以更好地模拟混凝土损伤发展速度等特点，便于工程应用。通过混凝土材料单轴受拉和受压试验及混凝土偏心三点弯曲梁算例验证了模型的有效性后，将该模型有效应用于某砾石土心墙堆石坝防渗墙的三维破损分析中。

关键词:混凝土防渗墙;近场动力学;均匀化多尺度方法;等效损伤模型

Abstract:

The concrete cut-off wall has been widely used in high embankment dams constructed in the overburden in China. The local failure of the wall embedded in the soil may occur since it is subjected to the giant water pressure， earth pressure， and the uneven settlement between the soil and the concrete. Generally， discrepancies of structure dimensions across diverse scales and accurate descriptions of the complicated failure involved in this process are crucial but difficult to be considered. In this paper， based on the multi-scale homogenization method of peridynamics， an equivalent damage model of concrete cut-off wall in high embankment dams was proposed. The concept of the model was given， and based on the damage mechanism of the cut-off wall， the aforementioned equivalent damage model was established. This model is characterized by its simplified formula， few parameters with valid physical meanings， and unified expressions of the tension and compression damage. The new index number renders the model to be capable of more accurately simulating the damage evolution process of concrete. The model proposed is easy to be employed in engineering practices. After the validation of the model proposed through concrete material tests and an eccentric three-point bending concrete beam test， it was employed to analyze the failure of the cut-off wall in a high gravel earth core rockfill dam in 3D.

Key words:concrete cut-off wall;peridynamics;homogenization multiscale method;equivalent damage model