广东省汤溪水库大坝抗震稳定性分析

汤溪水库始建于1959年,当时未对地震设防。为响应“国际减灾十年”号召,有关部门要求对该水库大坝的抗震能力进行复核。 在研究区的地震地质、地震活动性以及深部地球物理场等资料的基础上,划分出四个潜在震源区,并用概率地震危险性分析方法,给出复核大坝抗震能力的两个等级的地震动:取地震复发周期475年(相当于地震基本烈度)的峰加速度142.2cm/s~2,复发周期2474年(相当于“罕遇烈度”)的峰加速度229.6cm/s~2。 在上述地震动下,利用三种方法对大坝抗震能力进行复核:1.水工建筑物抗震设计规范SDJ10—78的拟静力法;2.有限元整体永久变形分析法;3.有限滑动永久变形分析法。根据上述三种方法的复核结果,主坝可以抗御地震基本烈度的作用;在罕遇烈度下,几种方法的结果稍有不同;拟静力法的最小安全系数K=1.08,稍小规范规定的1.1;整体永久变形算出的最大水平永久变形10.8cm,估计坝顶和坝坡会出现规模不大条数不多的纵、横向裂缝,因此是可以接受的,有限滑动分析的几种类似的方法给出的结果差别较大,尤其是Romo法,得出水平和垂直最大永久变形分别为66cm和21cm。综合来看,在罕遇烈度下,主坝的抗震能力处于临界状态。副坝抗震能力高,在罕遇烈度下也是令人放心的。

SEISMIC STABILITY ANALYSIS OF THE EARTH DAM OF TANGXI RESERVOIR

Tangxi reservoir was constructed on Huanggang River, and the dam is composed of the main dam 43m in height and the auxiliary dam 35 in height. The design capacity of the reservoir is 2. 86. 102 m3. The dam was built in 1959. and no measures were taken against earthquake. In order to respond to the call of "International Decade for Natural Disaster Reduction", it is required by the related authority to check the earthquake resistance capability of the dam. Firstly, the criteria for checking earthquake resistance capability of the dam are given by means of probabilistic hazard analysis, i. e. peak acceleration of M2. 2 cm/s2 and 229. 6cm/S2 are taken to be corresponding to the basic seismic intensity and "extreme intensity", respectively. Three methods are used for re -estimating earthquake resistance capability of the dam. 1 ) The quasi -static method ;2) Finite element analysis of averall permanent deformation; 3) Finite sliding deformation analysis. The result of re-estimating by the above -mentioned methods indicate that the main dam has ability to resist the action with the basic intensity. For the peak acceleration of 229. 6m/s2, the three methods give slightly different results. The minimum safety factor k= 1. 08, obtained by the quasi -static method is slightly lower than that specified in the Code (1. 1) ; the maximum horizontal permanent deformation calculated from the overall deformation is 10. 8 cm, which is acceptable; the horizontal and vertical pemanent deformations calculated by Newmark's.Makdis'and Sarma's methods in the finite sliding analysis are very small and calculated by Romo's method are 66. 0 cm and 21. 1 cm, respectively, indicating that the earthquake resistance capability of the main dam reaches a critical state in the case of extreme intensity. The earthquake resistance acpability of the auxiliary dam is high.