Numerical Simulation Experiments Of Seismic Responses Of Micropile Foundations In Liquefiable Soils

The micropile, which is of higher bearing capacity, convenient construction and easily arrangement, is a new type pile. Recently, it was widely used to reinforce or remodel or rectify the structure, and the dam and the foundation of tower around the world. But the application history of micropile is short, and the pile-soil interaction is much complicated. There is no an identical issue for seismic design of micropiles, especially the seismic design of micropile in liquefiable soils. Consequently, the research on numerical simulation experiments of seismic responses of micropile foundations in liquefiable soils is great important.Based on the effective stress analysis program FlipGenCN, three numerical simulation models in which the inclination degree of micropile are 0°,15°,25°, respectively, were constructed to investigate the performances of micropile in liquefiable soils subjected to seismic loading and self-weight loading. The principles of accelerations of ground and pile, the lateral displacements, the bending moments of the pile and the express pore water pressure in the ground with different boundary conditions are discussed. Moreover, the pile-soil interaction mechanism is further investigated. Some interesting results are reached as shown in the following:1) Under self-weight condition, the maximum bending moments of micropile appear two peak values at post of 1/5 pile length from pile top and from pile bottom, respectively.2) The maximum bending moment of the micropile occurs at 1/3 pile length from surface. For input sine wave and earthquake wave, the seismic responses of micropile of same inclination angle are different during earthquakes. The bigger the inclination degree of micropile, the smaller the lateral displacement at the pile head is.3) The acceleration amplitude in the ground decreases with decrease of buried depth. However, the acceleration amplitude of pile firstly decreases, then increase with the decrease of the buried depth.4) The growth value of the express pore water pressure is bigger in the pile groups than outside the piles during earthquakes. The pile-soil relative...