小麻柳尾矿库2号拦泥坝工作性态及稳定安全性分析

Analysis of the working state and stability safety of No.2 mud dam in Xiaomaliu Tailing Pond

小麻柳尾矿库2号拦泥坝修建在覆盖层地基上,虽然坝高较低,但是由于软基上重力坝工程经验不多,其坝体工作性态及抗滑稳定安全性需引起重视。运用有限元分析方法对小麻柳尾矿库2号拦泥坝开展计算分析,分别从地基变形、坝体应力与变形、重力坝整体稳定性等方面进行研究,分析了该软基上重力坝的工作性态及特征,并探讨了该坝的抗滑稳定安全性。研究分析结果表明:采取宽厚、较对称的坝体剖面,并在坝体底部设置垫层,有效地减小了地基压力,坝基面上的应力分布较均匀,除坝踵、坝趾局部以外坝基面竖直向应力较低,约为0.2 MPa,地基不均匀沉降得到有效控制,校核洪水工况坝基面最大不均匀沉降仅为2.2 cm;由于坝体底部垫层宽度较大,增大与地基接触面的面积,且坝基设置有抗滑齿墙,沿坝基面最小抗滑稳定安全系数达到3.23。通过计算分析,证明本工程所采取的坝体设计方案及结构措施是合适的,可以保证该坝具有良好的工作性态及较高的稳定安全性。另外,分析计算结果还表明,与岩基重力坝相比,该坝的应力变形表现出一些不同的特征:坝底水平顺河向拉应力较大,坝体水平位移较大。这需在进行软基上的重力坝设计和分析工作中予以重视。

The No.2 mud dam in Xiaomaliu Tailing Pond is built on the overburden foundation. Although the height of the dam is low, its working state and safety against sliding deserve attentions due to inexperience in the gravity dam project built on soft foundation. In this paper, finite element method is used to analyze this dam,including foundation deformation, the stress and deformation of the dam body, and the stability of the dam against sliding. Furthermore, studies and analyses are conducted to explore the working state and characteristics of this dam as well as its stability against sliding. The study results show that adopting wide, thick and more symmetrical dam section, and setting a cushion at the bottom of the dam body can effectively reduce the earth pressure, and the stress distribution on the surface of the dam foundation is relatively uniform. In addition,except the local areas around the heel and toe of the dam, the vertical stress of the foundation is low, about 0.2 MPa. The non-uniform settlement of foundation is also effectively controlled, and the maximum value of which is only 2.2 cm during spillway design flood. Due to the large width of cushion layer at the bottom of the dam body, the area of the contact surface with the foundation is increased. Furthermore, the dam foundation is provided with anti-sliding tooth wall. These structure modifications greatly improve the sliding stability, and the minimum value of sliding stability is raised to 3.23. The study of this paper proves that the dam design scheme and structural modifications adopted in this project are suitable, ensuring a fair working state and stability of the dam. The analysis and calculation results show that compared with gravity dams built on rock foundation, the stress deformation of the dam shows some different characteristics: the horizontal tensile stress along the river flow at the bottom of the dam and its displacement along the river flow are significantly larger. These characteristics should be emphasized in the design and analyses of gravity dam on soft foundation.