预应力锚索的三维数值模拟及其应用研究

STUDY ON 3D NUMERICAL SIMULATION OF PRESTRESSED ANCHOR CABLE AND ITS APPLICATION

预应力锚索加固作为岩土工程的一种主要技术已得到日益广泛的应用,但现有的数值模拟方法却不能很好地反映这一实际加同效果。根据预应力锚索中自由段和锚固段不同的作用机理,建立了一种新的能够施加预应力的三维数值模拟方法。具体说来就是,锚固段采用空间杆单元来模拟,而自由段则采用一种三维杆单元,即只允许轴向变形、具有一个白由度、2个结点的线单元,其特有的双线性刚度矩阵只能承受单向拉伸或者单向压缩,而不能承受弯矩;当该单元选择单向拉伸时,单元一旦受到压力,则刚度矩阵自动被删除,这个特征能够很好地模拟钢索类问题。在此基础上,分析研究了在预应力的作用下锚索和岩体的受力变形特征及其影响因素,揭示了预应力锚索锚同的效果与机理。最后,将其应用于工程实践中,验证了该方法的有效性。

Prestressed anchor cables have been widely used as a main reinforcement method in geotechnical engineering, but existing numerical method cannot simulate their effect successfully. According to different working mechanisms between free segment and consolidated segment, a new 3D FEM is presented, which can simulate the prestress. Consolidated segment is simulated by space rod element, while the free segment use a special rod element which has two nodes and one degree of freedom. Its particular bi-linear stiffness matrix can endure unilateral tension or unilateral compression, but not moment. When the element is chosen to endure tension only, the stiffness matrix will be deleted automatically if it is under compression. This character can successfully simulate tightwire. On this basis, the load-deformation characteristics and influence factors of anchor cable and rock mass are analyzed. Therefore, the reinforcement effect and mechanism can be explored. Finally, this method is successfully used in a case.