空腹混凝土坝振动响应试验研究

Experimental Study on Vibration Response of Hollow Concrete Dam

针对平原地区土层条件较差和地形条件有限的情况,提出一种新型坝——空腹混凝土坝。采用振动台模型试验技术,研究加速度峰值、库水位及防渗墙对该新型坝动力响应的影响。结果表明:(1)在自由场坝基中设置结构可以降低坝基的超孔压响应,削减坝基液化程度。(2)非自由场工况中,加速度峰值的增大加强了坝基的振动幅度,加剧液化程度;坝体上游库水位的存在增加了坝基的有效应力从而降低液化程度;坝基中防渗墙的存在增加了孔压的消散从而降低液化程度。总体来说,加速度峰值对液化程度影响最大,库水位影响次之,防渗墙影响最小。(3)库水位的存在增加了坝体的受力程度导致坝体水平位移响应大于空库工况,防渗墙的存在降低了坝基中的水力梯度导致坝体响应低于无防渗墙工况。但在试验过程中坝体并没出现明显的水平位移变化。

In view of the poor soil conditions and limited topographic conditions in plain areas,a new type of dam,hollow concrete dam,is proposed.The shaking table model test technology was used to study the effects of acceleration peak,water level and impermeable wall on the dynamic response of the new dam.The results show that:(1)structures in the free field dam foundation can reduce the ex-cess pore pressure response and the degree of liquefaction of the dam foundation.(2)In the non-free field working condition,the increase of the acceleration peak strengthens the vibration amplitude of the dam foundation and intensifies the degree of liquefaction;The presence of the reservoir water level in the upstream reservoir of the dam body increases the effective stress of the dam foundation,thereby reducing the degree of liquefaction;The presence of an impermeable wall in the dam foundation facili-tates the dissipation of pore pressure and thus reduces the degree of liquefaction.In general,the accel-eration peak has the greatest influence on the degree of liquefaction,followed by the reservoir water level,and the impermeable wall has the least impact.(3)The existence of the reservoir water level in-creases the stress level of the dam body,resulting in a greater horizontal displacement response of the dam body compared to the empty reservoir condition,and the presence of the impermeable wall reduc-es the hydraulic gradient in the dam foundation,resulting in a lower response of the dam compared to that of without the impermeable wall.However,during the experiment,there was no significant hori-zontal displacement change in the dam body.