胶凝砂砾石坝坝体和井廊系统的静动力安全性研究

Study on static and dynamic safety of cemented gravel dam body,shaft and gallery system

采用三维有限元法,对某胶凝砂砾石坝开展静、动力结构计算,重点分析了坝体和井廊系统的动位移、加速度和动应力分布规律。结果表明:坝体动位移、加速度和动应力反应分布符合一般规律,其中顺河向、竖向和坝轴向动位移极值分别为0.29 cm、0.13 cm和0.08 cm,顺河向、竖向和坝轴向加速度极值分别为5.88 m/s^(2)、4.53 m/s^(2)和2.71 m/s^(2),静动叠加后的坝体第一主应力最大值为1.20 MPa,第三主应力最小值为-1.78 MPa,均小于相应材料的抗拉和抗压强度,因此大坝满足强度要求。静力条件下,井廊道系统的拉应力和压应力极值均小于相应的规范允许值;地震作用下,竖井和廊道局部区域出现较大的拉、压应力,其中瞬时动拉应力超过混凝土的动抗拉强度,通过加强井廊系统的局部配筋,总体上能够满足安全运行的要求。

The static and dynamic response of a cemented sand and gravel dam in Yunnan Province is calculated by using three-dimensional finite element method.The distribution laws of dynamic displacement,acceleration and dynamic stress of the dam are emphatically analyzed.The result show that the dynamic displacement,acceleration and dynamic stress response distribution of the dam conform to the general laws,with the extreme values of dynamic displacement along the river,vertical and dam axial being 0.29 cm,0.13 cm and 0.08 cm,and the extreme values of acceleration along the river,vertical and dam axial being 5.88 m/s^(2),4.53 m/s^(2) and 2.71 m/s^(2),respectively.The maximum value of the first principal stress of the dam after static and dynamic superposition are 1.20 MPa,and the minimum value of the third principal stress is-1.78 MPa,both of which are less than the tensile and compressive strength of the corresponding materials.Under static conditions,the extreme values of tensile stress and compressive stress of shaft and gallery system are less than the allowable values of the code.Under the action of earthquake,the local area of shaft and gallery has large tensile and compressive stress,in which the instantaneous dynamic tensile stress exceeds the dynamic tensile strength of concrete.By strengthening the local reinforcement of shaft and gallery system,the requirements of safe operation can be met on the whole.