Simulation test and numerical analysis of the performance of hydraulic support for pile foundation

In view of the poor applicability of the traditional roadway portal hydraulic support due to its shortcomings such as bulky bottom beam, large space occupation and inconvenient installation and dismantling. Through theoretical analysis, model test, and numerical simulation, the supporting performance of roadway pile foundation portal hydraulic support was studied. Based on analyzing and summarizing the advantages and disadvantages of traditional roadway portal hydraulic supports, a new type of roadway hydraulic support based on the stable structure system of support-pile foundation-surrounding rock was proposed. A simulation test model of support performance was established, and the digital speckle correlation method was used as the observation method to compare and analyze the support performance of traditional portal hydraulic support and pile foundation portal hydraulic support in terms of horizontal displacement of surrounding rock, bottom drum value, and maximum shear strain. A numerical simulation model of support performance was constructed. The displacement of surrounding rock of roadway under different pile lengths, different pile diameters, and different pile foundation angles was calculated, and the influencing factors of roadway pile foundation gantry hydraulic support performance were analyzed. The results show that: ① The comparative analysis of the similar simulation test results shows that the deformation of the lower rock layer of the surrounding rock of the roadway under the support of the roadway pile foundation portal hydraulic support is significantly reduced. The maximum horizontal displacement, bottom drum value, and maximum shear strain are reduced by 21%, 12%, and 32.6%, respectively. ② The numerical simulation results show that the horizontal displacement of the surrounding rock of the roadway diffusion decreases from the sidewall of the roadway under the roadway pile foundation portal hydraulic support. The pile foundation has a partitioning effect on the roadway bottom drum, and the bottom drum only appears between the piles, and the bottom drum value decreases with the increase of the distance from the rock layer to the bottom surface of the roadway. The plastic deformation of the surrounding rock of the roadway is distributed in a butterfly shape, mainly concentrated at the top of the roadway, on both sides, and between the piles, and the plastic deformation area at the bottom of the roadway is separated by the pile foundation. ③ The analysis of the influencing factors indicates that increasing the length and diameter of the pile foundation can reduce displacement at the base of the roadway and effectively control bottom drum effects. However, the benefits of the pile foundation diminish once its length surpasses a certain point. Additionally, increasing the angle of the pile foundation can lead to greater displacement at the roadway bottom and worsen the bottom drum effects, which is detrimental to controlling the deformation of the surrounding rock.