库水位升降对堆石坝心墙的水平变形影响分析

Influence of Water Level Fluctuation on the Horizontal Displacement of Core Wall of Rockfill Dam

为研究库水位升降对堆石坝心墙的水平变形影响,将土石坝心墙类比为竖直悬臂梁,上游侧受到上游坝壳不均匀的分布土压力和随时间变化的水压力,下游侧也同理受到下游坝壳相应土压力和水压力。研究表明:库水位上涨导致心墙发生向下游转动趋势,上游土压力逐渐减小,下游土压力逐渐增大,当二者分别达到主动土压力和被动土压力的极限状态时,土体即将产生滑动,定义此时的心墙挠度为理论心墙稳定挠度fs;若心墙实际水平位移量大于fs,则可以大致判定心墙两侧土体发生了相对滑动,可能导致产生局部纵向裂缝趋势。假设土石坝加固工程中采用的混凝土防渗墙的工况和条件类似,研究成果可直接应用于水平变形量计算并简单评估安全性。

The core wall of earth-rockfill dam is considered as a vertical cantilever beam,the upstream side of which is controlled by the pockety earth pressure of the upstream shell and the time-varying water pressure,and the downstream side is also controlled by the corresponding earth pressure of the downstream shell and the water pressure similarly. When the reservoir water level rises and the core wall has a tendency to turn to the downstream side,the upstream earth pressure gradually decreases and the downstream earth pressure gradually increases. Once the earth pressure on both sides reaches the limit active and passive earth pressure respectively,slippage is likely to take place,and the core wall deflection at this time is defined as the safe deflection fs. If the measured actual lateral displacement of the core wall is larger than fs,we can roughly determine that relative sliding of the soil on both sides of core wall exists,which may generate local longitudinal crack. The research result can be applied directly to the calculation of horizontal deformation and safety assessment for concrete core wall of similar conditions.