Centrifugal shaking-table test study on the dynamic responses of rock slope containing weak interlayer reinforced with prestressed composite structure

Abstract

Rock slopes containing weak interlayers are susceptible to seismic-induced sliding failure along the interlayer planes. This study aims to investigate the dynamic response of prestressed composite structures reinforced rock slopes containing weak interlayers. Based on a typical slope prototype in Ludian, Yunnan, a centrifugal model test was conducted at a geometric similarity ratio of 1:50, using four seismic intensity levels (2.50 –10.00 g) and three prestress levels for anchor cable (12 –120 N). There exists an evident dual-threshold effect of seismic intensity and prestress levels on the acceleration and displacement responses of slopes, with the critical thresholds being 5.00 g and 60 N, respectively. The dynamic response of the slope interior and surface exhibits remarkable elevation amplification, which peaks at the slope top: the amplification factor increases initially and then decreases with the seismic intensity and prestress level. The deformation of slope is predominantly concentrated at the slope top: the displacement shows two distinct variation trends: it increases rapidly at first followed by slow growth with rising seismic intensity, while it decreases sharply initially and then diminishes mildly with growing prestress. The peak bending moment of anti-slide piles and maximum axial force of anchor cables both increase with seismic intensity. The bending moment of piles is positively correlated with axial force of anchor cables under varying seismic intensity, whereas a negative correlation exists between the two parameters under different prestress levels. This indicates that the growth of seismic intensity aggravates damage of rock mass and weakens the stiffness of the slope system. By contrast, appropriately elevating the prestress of anchor cables can realize internal force redistribution, thereby strengthen the synergistic bearing performance of the prestressed composite structure. The findings reveal key thresholds for seismic response and prestress regulation in pile-anchor reinforced bedding rock slopes. They provide experimental support and theoretical reference for the seismic design and safety evaluation of such composite supports in high-intensity seismic regions.