红沿河核电取水隧洞进水口高边坡抗震稳定分析

Seismic Stability Analysis of High Slope at the Intake Tunnel of Hongyan River Nuclear Power

摘要:

以红沿河核电取水隧洞进水口高边坡为背景，介绍了核电工程中边坡抗震稳定分析的原理和分析方法。依次采用滑动面法、静力有限元法和动力有限元法计算该边坡的抗震稳定性，得到其在地震作用下的安全系数及滑动面位置；根据安全系数时程曲线进一步得到边坡最小安全系数和最小平均安全系数。结果表明天然边坡安全系数不满足《核电厂抗震设计规范》的要求，必须进行削坡加固。本文的计算方法和分析成果对于类似核电工程中的高边坡抗震稳定分析具有一定的指导意义和参考价值。

Abstract:

Several Chinese nuclear power plants are in earthquake-prone areas.Thus，slope failures due to earthquakes can disrupt the normal operation of nuclear power plants.Seismic design safety calculations for nuclear power plants take the advantage of computation methods such as the slip surface，the static finite element，and the dynamic finite element method.The current nuclear specifications recommend using the three different methods of analysis that satisfy the regulatory requirements without giving additional guidance.Seismic slope stability analysis was used to examine the intake tunnel of the Hongyan River nuclear power plant.The model boundary conditions for horizontal and vertical seismic motion were established.When the lower boundary is fixed，there is the effect of the vertical displacement on the lateral boundary.When the lower boundary for the horizontal seismic motion is fixed，there is the effect of the horizontal displacement on the lateral boundary.The input seismic data were taken from earthquake evaluation reports.The peak horizontal acceleration of the sl-2 ground motions is 0.18 g，and the vertical acceleration peak is 0.12 g.The safety factor for the high slope and sliding surface position subjected to seismic loading is calculated first by the sliding surface method，and then by the static and dynamic finite element methods.Furthermore，the minimum safety factor and the minimum average safety factor of the slope are obtained according to the history curves of the safety factor.For vertical seismic motion，the sliding surface method and the static finite element method result in safety factor values of 1.296 and 1.326，respectively.The minimum safety factor is 1.163.The results of the calculations and the analysis suggest reasonable improvement for the side slope.The cutting slope unloading scheme is necessary because the safety factor of the natural slope cannot satisfy the specifications of the seismic design code for nuclear power plants.For vertical seismic motion，the calculated excavation slope safety factor with the sliding surface method is 1.524，whereas the safety factor calculated with the static finite element method is 1.508.The minimum safety factor calculated with the dynamic finite element method is 1.307.The calculated safety factor satisfies the code requirements after the cutting slope unloading scheme is adopted.Evidently，the calculation methods can be used in the seismic slope stability analysis of similar conditions.