## 4 Conclusions  
A 1:70 scale model was designed and constructed to study the bridge foundation on a gravel soil slope reinforced with the front and back rows of anti-slide piles, and loaded with the El Centro wave in the laboratory shaking table test. The stress-induced deformation of the pier pile foundation and the front and back rows of the anti-slide piles as well as the acceleration response characteristics of the slope were analyzed. According to the experimental phenomena, the following conclusions were drawn:  
(1) When the front and back rows of anti-slide piles were used to reinforce the bridge foundation on the gravel soil slope, the back-row anti-slide piles withstood most of the landslide thrust and played the main role in seismic reinforcement. The front-row anti-slide piles could provide horizontal resistance to the pier foundation, and the distance had to be small. (2) The pier pile foundation had a large bending moment near the top and the sliding surface, where the piles had to be reinforced. The rate of attenuation of the bending moment from the top of the pile along its depth was related to the soil resistance, and the reasonable spacing of the back-row anti-slide piles and bridge foundation should be controlled. If the back-row anti-slide piles were too closed to the bridge foundation, the dynamic interaction was strong. If the spacing was large, the soil inertial force behind bridge pier increased and went against the deformation of bridge piles. (3) The test results showed that the stress-induced deformation of the pile foundation behind the pier was larger than that in front of the pier. It is recommended that the pile foundation behind the pier act as the analysis subject in the seismic reinforcement design so as to control the stress-induced deformation of the pile shaft. The engineering design of lowering height and weight of the bridge is advantage for the forced deformation of the pile foundation. (4) For a gravel soil slope, the peak earth pressure behind the back-row anti-slide piles had a triangular distribution. After the pile shaft cracked, it still had a certain horizontal load-bearing capacity. As the cracks propagated, the tensile steel bars gradually yielded, and the concrete was crushed, causing the bearing capacity of anti-slide piles to gradually decrease. The distance between the crack and the sliding surface was approximately one fifth of the length of the anchoring section of the anti-slide pile, where the pile was subjected to a combination of a large shear and bending moment. (5) The PGA amplification factor of the slope had a vertical amplification effect. As the height increased, the PGA amplification factor tended to increase and had a layered distribution. The regions with a large PGA amplification factor were the sliding section and the steep section of the slope, while the region between the pier and the back-row anti-slide piles were kept with a small PGA amplification factor. The bedrock was an approximately rigid body and, thus, the increase in the PGA amplification factor was very small. (6) The test results showed that it was feasible to analyze the distribution pattern of the PGA amplification factor of the slope by using the two-dimensional equipotential map, which could meet the basic requirements of the macro analysis of the slope acceleration response. The mapping accuracy was related to the number and the layout mode of the horizontal acceleration measurement points. For the key monitoring regions, the number of horizontal acceleration measurement points should be increased and a reasonable layout scheme should be formulated. [PERSON] and [PERSON] designed the model test and wrote the original manuscript. [PERSON] investigated literature and [PERSON] supervised. [PERSON] and [PERSON] did the review and editing. All authors have read and agreed to the published version of the manuscript. This research was funded by the Major Project Program of the Scientific and Technological Research and Development Plan of the Ministry of Railways, China (Grant No.