不同承压衬垫的管片接头力学性能分析

Analysis on Mechanical Properties of Segment Joints with Different Pressure Pads

利用能够体现管片接头承压衬垫和端面混凝土共同变形的改进条带算法,结合衬垫和混凝土非线性材料关系曲线,研究不同承压衬垫条件下管片接头端面压应力分布特征和承压衬垫对接头力学参数的影响。研究表明:随着弯矩增大,当接缝无承压衬垫时,端面压应力分布形态从近似三角形分布向抛物线分布再向直线与抛物线组合分布形态转化;当接缝有承压衬垫时,端面压应力分布形态从近似凹弧线分布向双向弯曲弧形分布再向直线与双向曲线组合分布形态转化,并随承压衬垫厚度增大更加明显;随着承压衬垫厚度增大,管片接头抗弯刚度明显减小,螺栓拉应力有所增加,同时明显加大了接缝张开所需弯矩值水平;承压衬垫具有减弱接头弯曲刚度和减少整环衬砌接缝张开数量的作用,但基本不能改变接头承载能力和极限变形能力。

By adopting the improved strip arithmetic method which reflects common deformations of pressurebearing pads and concrete ribs of segment joints and utilizing the curves of nonlinear materials of pressure pads and concrete, compressive stress characteristics of concrete ribs and influence of pressure pads on mechanical parameters of segment joints under the condition of different pressure-bearing pads were studied. The study shows as follows： If segment joints have no pressure pads, along with increasing of the joint bending moment, the compressive stress distribution pattern on the concrete rib surface will change in shapes from an approxi- mate triangle to a parabola and then to combination of the straight line and parabola; if segment joints have pressure pads, along with increcsing of the joint bending moment, the compressive stress distribution pattern will change in shapes from single concave arc to compound bending arc , and then to combination of the straight line and parabolic, furthermore the changing tend will become more obvious with increasing of the pad thick- ness;along with increasing of the pad thickness,the bending stiffness of segmental joint will reduce obviously, the blot tensile stress will increase to some extent, and the bending moment essential to seam opening will be enlarged obviously; pads possess the functions of weakening joint bending stiffness and reducing the number of gaps of the entire ring, however,basically speaking,they cannot play the roles of changing the joint load bearing capacity and limiting deformation.