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岸坡锚碇区承载将显著改变库岸地质力学条件,此外通航水位周期性涨落也将极大影响坡体稳定性。目前永善县月亮湾特大桥云南岸坡通航水位在601~560m之间周期性波动,地下水渗流状态将发生较大改变,锚碇承载后可能导致岸坡失稳。利用Plaxis有限元程序,计算了水位波动下坡内位移场分布,探讨了库岸塑性点发展,采用强度折减法对比分析了锚碇承载前后坡体安全系数变化,得到了坡体滑裂面发育过程。研究表明:坡体总位移极值较小,极值区主要分布在主塔以下陡坡台阶处,随水位降低陡坡位移逐渐发展;不利工况坡体塑性点主要分布在锚碇端部和陡坡后部,随水位降低锚碇塑性区不断发展,延伸至基岩-中风化层界面;锚碇及桩基施工后,不利工况安全系数在1.3~1.4之间;最高通航水位下降20~30m时,施工后安全系数相比施工前降幅较大;不利工况岸坡危险滑裂面集中出现在锚碇区,坡体未形成明显滑裂面。
The loading of bank slope anchor zone will significantly change the geotechnical conditions of the bank bank. In addition, the periodic fluctuation of navigable water level will also greatly affect the slope stability. At present, the navigable water level of Yunnan Peninsula over the Moon Bay Bridge in Yongshan County fluctuates periodically between 601 and 560 meters, and the seepage status of groundwater will change greatly. After the anchorage, it may cause instability of the bank. Plaxis finite element program was used to calculate the displacement field distribution in down-slopes of fluctuating water level. The development of plastic points in bank and bank was discussed. The change of safety factor of slopes before and after anchorage was compared by strength reduction method. process. The results show that the extreme value of total slope displacement is small, and the extreme value zone is mainly distributed on the steep slope below the main tower, with the gradual development of steep slope displacement as the water level decreases. The plastic point of the slope is mainly distributed at the end of the anchorage and the steep slope With the water level decreasing, the plastic zone of anchorage is continuously developed and extended to the interface of bedrock-mesoderm. After the anchorage and pile foundation construction, the safety factor of unfavorable condition is between 1.3 and 1.4; when the highest navigable water level drops 20 ~ 30m , And the safety factor after construction dropped more than that before construction. In the unfavorable working condition, the dangerous slip surface occurred suddenly in the anchorage zone, and no obvious slip surface was formed on the slope.