框架预应力锚杆边坡支护结构动力计算方法研究

STUDY ON DYNAMIC CALCULATION METHOD FOR FRAME SUPPORTING STRUCTURE WITH PRE-STRESS ANCHORS

  • 摘要: 考虑了土体与结构的性质及相互作用,建立了框架预应力锚杆边坡支护结构动力计算模型。该模型根据框架预应力锚杆的实际工作机理,自由段和锚固段分别简化为两段均匀弹性圆杆,将土体对锚固段的作用处理成一个线性弹簧和一个与速度有关的阻尼器,把框架对锚杆的惯性作用简化为集中于锚杆外端头上的等效质量加以考虑,基于前述简化,推导出框架预应力锚杆边坡支护结构协同工作的水平地震动力运动方程,并进行了地震响应分析。最后将提出的方法应用于实际工程,并与数值模拟、振动台试验进行了对比,结果表明吻合较好,说明提出的方法是实用、可靠的。通过该模型可以得到框架预应力锚杆边坡支护结构在水平地震作用下的动位移、锚杆轴力地震响应、地震作用下的轴力峰值沿边坡高度及锚杆轴向的分布规律,为框架预应力锚杆边坡支护结构的动力分析与抗震设计提供了理论基础。

     

    Abstract: Considering the nature of the mutual influence between a structure and its supporting soil, a dynamic calculation model of a supporting frame with pre-stress anchors for the slope stability is established. According to the actual working mechanism of the frame with pre-stress anchors, the free segment and anchorage body of an anchor is respectively simplified two section uniform elastic round rods. The interaction between soil and anchors is treated with a linear spring and a damped system related with velocity. The influence of the frame upon the anchor is simplified for equivalent mass. Under the condition of a horizontal earthquake excitation, the vibration equation is deduced based on being mentioned ahead, and the analytical solutions are obtained. The method is applied to a case record for illustration of its capability. In order to verify the method, a 3-D nonlinear finite element software (ADINA) is used to analyze the seismic performance of this case, the results of comparison with that of the proposed approach and that of the finite element method and that of a shaking table test show a good agreement. The results of analysis reveal that this simplified calculation model is feasible. The seismic displacement response, the anchors axial force increment response, the distribution of axial force along slope height and anchors axis can be obtained through the established model. The calculation model provides a new approach for the earthquake analysis and aseismic design of slope stability supported by a frame with pre-stress anchors.

     

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