Energy‐based analysis of seismic damage mechanism of multi‐anchor piles in tunnel crossing landslide area

To study the damage mechanism of multi‐anchor piles in tunnel crossing landslide area under earthquake,the damping performance of multi‐anchor piles was discussed.The energy dissipation springs were used as the optimization device of the anchor head to carry out the shaking table comparison test on the reinforced slope.The Hilbert spectrum and Hilbert marginal spectrum were proposed to analyze the seismic damage mechanism of the multi‐anchor piles,and the peak Fourier spectrum amplitude(PFSA)was used to verify the effectiveness of the method.The results show that the seismic energy is concentrated in the high‐frequency component(30-40Hz)of the Hilbert spectrum and the low‐frequency component(12-30 Hz)of the marginal spectrum.This indicates that they can be combined with the distribution law of the PFSA to identify the overall and local dynamic responses of the multi‐anchored piles,respectively.The stretchable deformation of the energy‐dissipation springs improves the coordination of the multi‐anchor piles,resulting in better pile integrity.The damage mechanism of the multi‐anchor piles is elucidated based on the energy method:local damage at the top and middle areas of the multi‐anchor piles is mainly caused by the low‐frequency component(12-30 Hz)of the marginal spectrum under the action of 0.15g and 0.20g seismic intensities.As the seismic intensity increases to 0.30g,the dynamic response of the slope is further amplified by the high‐frequency component(30-40 Hz)of the Hilbert energy spectrum,which leads to the overall damage of the multi‐anchor piles.

Dynamic Behavior of Double-Row Pre-stressed Anchor Piles under Earthquake Conditions

To investigate the seismic performance of the double-row pre-stressed anchor piles （DRPAPs） on the Yuxi-Mengzi railway, FLAC3D was used to construct a three-dimensional model. Using Koyna earthquake records as input motions, dynamic time-history analyses were carried out. In the analyses, we compared earth pressure on the front and back of the piles and deformation of the piles under different seismic forces with or without anchor cables. With the anchor cable present, the earth pressure on the back of the pile＇s free section increases, but that on the back of the pile＇s anchorage section decreases. Also, with anchor cables, the earth pressure on the front of the upper pile decreases, and that on the back of the lower pile decreases.

Study on the Horizontal Movement State of Suction Anchor Piles for Offshore Wind Power during Horizontal Pulling

The subsea anchor piles of offshore wind power floating platform structures are mainly subjected to uplift and horizontal loads, and this paper focuses on the case of horizontal loads. A three-dimensional numerical simulation study of the horizontal pullout characteristics of wind power suction anchor piles in clay layers was carried out to reveal the horizontal movement state of the anchor piles during horizontal pile pullout, the range of pile depth at the pullout point where the horizontal movement is achieved (referred to as the horizontal movement range), the relationship between the pullout load and the ultimate load during the horizontal movement, and the optimal location of the pullout point for the horizontal movement. The results show that at certain pull-out points, the anchor pile produces an overall horizontal movement state under suitable horizontal pull-out loads. The depth of the pile pull-out point for horizontal movement is in the middle and lower part of the pile, i.e. 14.2 m to 14.5 m. The horizontal pull-out load of 24,000 kN at a depth of 14.5 m within the pile horizontal movement range of 14.2m to 14.5 m is the maximum ultimate horizontal pull-out load;the optimum pull-out point depth is 14.5 m at 0.275 L (L is the pile length). For each pull-out point of the anchor pile in horizontal movement, the horizontal pull-out load in horizontal movement and the horizontal ultimate pull-out load existed and it was found that the two values were not exactly the same, the values were compared and it was found that at the optimum pull-out point the value of the ultimate horizontal pull-out load/horizontal pull-out load in horizontal movement tended to 1.