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基于卸荷岩体的理论和方法,对大岗山水电站坝肩边坡进行研究。以大型通用有限元程序ADINA为计算平台,对比分析坝肩边坡卸荷后,不同地震加速度及不同锚固长度和锚固吨位在卸荷条件下关键点的位移和应力以及塑性区的变化规律,认为边坡开挖变形由两部分组成,一部分为卸荷回弹,另一部分是由于大吨位锚索施加后产生的朝向坡内的压缩变形。研究表明,由于锚索穿过V岩体底部界线,在可能的滑坡剪出口形成强大的阻滑键,增加锚索长度或吨位均可有效地减小坝肩塑性区,地震加速度为0.1g和0.15g时,在各加固吨位下均可能形成塑性区的贯通;在不同的地震加速度下,受不同锚固长度和锚固力影响,不同关键点处水平向位移呈现线性变化和非线性变化,非线性关系中的拐点应重点关注;若要减少岩体塑性区,相同比例下增大锚固长度效果更好。为了有效减少在高地震烈度时边坡塑性区的发育,建议采用增加120%的锚固长度。
Based on the theory and method of unloading rock mass, the dam abutment slope of Dagangshan Hydropower Station is studied. Taking the large-scale finite element program ADINA as the calculation platform, the displacement and stress of the key points under different unloading conditions and the changing rules of different plasticity of different earthquakes, different earthquake accelerations, different anchorage lengths and anchorage tonnage were analyzed and compared. The deformation of slope excavation is composed of two parts, one part is unloading rebound and the other part is due to the compressive deformation towards the slope generated by the application of large tonnage anchor cable. The research shows that as the cable passes through the bottom boundary of V rock mass, a strong block slip bond is formed at the exit of possible landslide cutters. Increasing the length or tonnage of the anchor cable can effectively reduce the plastic zone of the dam shoulder with an acceleration of 0.1 g and 0.15g, the plastic zone can be formed under each reinforced tonnage. Under different earthquake accelerations, the horizontal displacement at different key points changes linearly and nonlinearly under the influence of different anchorage length and anchoring force. The nonlinearity The inflection point in the relationship should focus on; to reduce the plastic zone rock mass, the same ratio to increase the anchoring length better. In order to effectively reduce the plastic zone of slope in high earthquake intensity, it is recommended to increase the anchorage length by 120%.