Centrifuge Model Test on Stratum Deformation Rule of Loess Road Tunnel Based on Double-hole Effect

In order to understand the stratum deformation rule of loess road tunnel under the influence of double-hole effect more comprehensively,four groups of model tests were carried out systematically with the centrifuge model test device,based on the thinking of first loading and then punching,and the influence of different double-hole clear distances on the stratum deformation of the loess road tunnel was researched.The test results showed that with the increase of double-hole spacing,the degree of the mutual influence between two holes will recede,and the stratum deformation curve close to the vault changes from single peak "V" shape to double peak "W" shape gradually.There exists the pressure arch effect,and the formation height of the pressure arch increase with the increase of double-hole clear distance.The sedimentation range and the sedimentation value of each layer of the anterior hole are larger than those of the subsequent hole,and the influence degree of the anterior hole on the subsequent tunnel will recede gradually with the increase of double-hole spacing.Selecting 0.5D spacing form,the stress and deformation influence area between holes forms easily,so it's necessary to reinforce the middle soil;selecting D spacing form and above,the steady wide-base bearing soil column between holes can form,so the reasonable spacing between two holes of closely spacing loess road tunnel can be D.