堆石混凝土是一种高度采用机械化施工的筑坝技术,目前堆石混凝土重力坝因保守设计通常设置较多横缝,会导致施工仓面窄、机械转动半径小等问题。打鼓台重力坝创新采用少设横缝的设计,中间坝段是目前最长堆石混凝土重力坝段,长134 m,水库已成功蓄水运行3年多。为掌握打鼓台重力坝的蓄水运行安全状态,该文结合大坝温度、渗压、位移监测结果和有限元仿真计算分析,开展大坝在不同荷载下的工作性态演化规律研究。结果表明：蓄水运行后,坝体的温度与渗压均处于正常范围,中间超长坝段无明显开裂或渗水现象,大坝运行状态良好。堆石混凝土绝热温升低,打鼓台超长坝段的最不利位置温升也不超过10℃,因此可适当放宽重力坝坝段长度,但建议靠近坝基的大仓面避开高温季节浇筑,以控制混凝土入仓温度、减小施工期温度应力。与普通坝段工况相比,超长坝段的应力状态基本满足要求,空库或蓄水状态下最大局部应力约2.5 MPa,上游防渗层宜设置钢筋网和短缝；越冬期超长坝段的上游面水位以上部位和下游面存在高拉应力；不分横缝整体浇筑重力坝需考虑坝体端部应力大问题。在蓄水超载工况下,即使超载倍数达10.0,坝体也尚未出现上下游贯通性屈服破坏,可以看出大坝的超载安全度与稳定性较高。该文可为今后堆石混凝土重力坝的结构设计与安全评价提供科学指导。
Rock-filled concrete (RFC) is a dam construction technique that heavily relies on engineering machinery. Because of the conservative design concept, currently, many transverse joints exist in RFC gravity dams, resulting in a narrow working space and a small radius for mechanical rotation. The Dagutai RFC gravity dam innovatively adopts a design with fewer joints, and it has the longest section (134 m) among all RFC gravity dams. The reservoir has been in operation for more than 3 years after its impoundment. To determine the safety state of the Dagutai gravity dam during the impoundment operation period, this paper researched the dam's working behavior under different loads, using dam temperature, seepage pressure, and displacement monitoring results, along with the temperature stress simulation of the finite element method (FEM). The results revealed that the dam body's temperature and seepage pressure are within normal limits, and the dam's longest section has no obvious cracking or seepage, indicating that the dam performed well during storage and operation. RFC's adiabatic temperature rise is low, as evidenced by the temperature rise of the most unfavorable position in the long section being less than 10℃. The section length of the RFC gravity dam can be appropriately extended, but the large lifting surfaces near the foundation should not be constructed during hot seasons, to control the initial temperature and reduce temperature stress during construction. Compared to standard dam sections, the long section's stress state meets the requirements, and the maximum stress can reach 2.5 MPa under empty or full reservoir conditions. Reinforcing mesh and short joints should be installed in the upstream impermeable layer. Overwintering in the upstream surface above water and the downstream surface can cause high tensile stress. If a gravity RFC dam with no joints is built, the large tensile stress at both ends of the dam should be considered. Even when the overloading factor is 10.0, there was no yield failure through the upstream and downstream of the dam, indicating that the overloading safety of the dam is high and the dam stability is good. This paper's research can provide scientific guidance for the structure design of RFC gravity dams in the future.
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