预应力锚索对锚索抗滑桩抗震性能的影响规律研究

As an important component of developing the seismic performance of the anti-slide pile with anchor cable, the influence mechanism of the prestressed anchor cable is still not clear. Taking a typical engineering as the research object, using the methods of centrifugal shaking table test, numerical simulation and mathematical statistics，the influence laws of anchor addition and parameters on the seismic performance of pile under strong ground motions are revealed, and the determining principle and selecting range of anchor parameters are given. Based on the Bei-hou mountain landslide engineering in Hanyuan which is reinforced by anti-slide pile with anchor cable, the geological model is generalized, and the effects of anchor addition or not and anchor angle to the seismic response of pile-slide mass system are researched by means of the centrifugal shaking table test. The numerical analysis models corresponding to centrifugal shaking table tests are constructed by FLAC3D and used to analyze the corresponding centrifuge test conditions, and the parameters of the constitutive model are optimized by comparing with the centrifuge test results. On the basis of the established numerical models, the expansion analysis is carried out from the aspects of the stress and deformation of pile, and the acceleration, deformation and stress field of the landslide, to study the influence of anchor addition and parameters and to reveal the influence mechanism and laws of anchor parameters. Utilizing the obtained seismic response data, combining with the method of mathematical statistics, the determining principle of anchor parameters is put forward and the selecting range is confirmed. The results of this research can provide a scientific basis for developing the seismic technology and optimizing the seismic design method of anti-slide pile with anchor cable.

预应力锚索是锚索抗滑桩发挥优异抗震性能的重要构件，但其影响机制尚不清晰。以典型工程为依托，采用离心振动台试验、数值模拟和数理统计相结合的途径，研究揭示强震动作用下锚索加设和锚索参数对抗滑桩抗震性能的影响规律，提出锚索参数的确定原则及取值范围。基于汉源背后山滑坡锚索抗滑桩加固工程，概化工程地质模型，利用离心振动台试验，研究锚索加设与否和锚索倾角对抗滑桩-坡体体系地震响应的影响；采用FLAC3D软件构建与离心振动台试验相对应的数值分析模型，分析相应试验工况，并与试验结果进行对比，反演优化本构模型参数；基于已建立的数值模型，进行拓展分析，研究锚索加设和锚索参数对锚索抗滑桩桩身受力及变形、坡体加速度场、变形场和应力场的影响，揭示其锚索参数的影响机理和规律；利用得到的地震响应数据，采用数理统计方法，提出参数确定原则，确定锚索参数取值范围。成果可为发展锚索抗滑桩抗震技术和优化抗震设计方法提供科学依据。

锚索抗滑桩是加固大型或超大型滑坡的重要手段，但是锚索参数对锚索抗滑桩抗震性能的影响机理尚不清晰。基于实际工程设计资料，结合现场工程地质勘察，构建了原型工程概化地质模型，建立并完成了锚索倾斜布设的离心振动台模型试验；对比多组离心模型试验结果，分析了锚索加设与否和加设角度对锚索抗滑桩地震响应的影响规律；采用常规土工试验、三轴试验和界面摩擦试验，获得了昔格达组粘性土静、动力力学参数；结合Plaxis3D软件，构建了不同锚索预应力和倾角的数值模型，揭示了锚索角度和预应力变化对锚索抗滑桩抗震性能的影响机理；利用试验和数值模拟获取的地震响应数据，结合关联分析和秩和比法，研究了坡体放大与桩身受力和变形的相关性，给出了坡体放大对桩身地震受力的影响排序；利用统计学方法，提取了预应力和锚固倾角的优化取值范围，提出了工程抗震设计的优化建议。结果表明，锚索水平加设改变了桩身地震动土压力和动弯矩分布形态，降低了坡体沉降和破裂程度，但是桩-锚索-土体动力相互作用导致桩身出现了附加正弯矩；锚索倾斜加设减小了桩身动土压力和动弯矩，限制了桩身的地震外倾变形，降低了桩-锚结合部位坡体的放大效应，保证了桩身震后合理受力状态的延续；锚索峰值轴力与桩头峰值位移呈正相关关系，锚索倾角的最优范围在15°-25°之间，预应力选取介于滑坡推力的20%-30%之间，过大或过小的预应力和锚索倾角均会导致锚索峰值轴力和坡体沉降的增大，降低锚索抗滑桩抗震性能；坡体不同位置的加速度放大与桩身受力均有关联性，桩-锚结合部位、临空面附近和高角度基岩面处的地震放大对桩身地震受力影响更加显著；锚索角度和预应力变化不能完全消除桩-锚索结合部位坡体的异常放大效应和桩头动土压力的增加，建议锚索抗滑桩抗震设计进行局部减震处理。成果可为进一步的科学研究提供原始数据，也可为优化锚索抗滑桩的抗震设计提供技术支撑，又为实际工程桩型选型提供科学依据。