Application of micro-piles in foundation reinforcement of a coal storage

With regard to the phenomenon of large settlement of a coal storage warehouse, by analyzing its foundation settlement variation rules at three different stages of the structural construction, initial coal storage and local empty warehouse, the causes leading to structural foundation settlement and the overall tilt are given, namely three causes of bad bearing stratum at end of micro-piles, improper service load and poor quality of cement deep mixing piles. Considering settlement control, a design concept of using the ultimate vertical bearing capacity of micro-piles and appropriately reducing the bearing capacity of the original composite foundation, reducing the number of reinforced piles by 50%, is proposed. By using the secondary grouting micro-piles, the dual requirements of coal storage warehouse foundation on strength and deformation are met, while the top micro-piles and the original caps, by adding cap and dowel-bar reinforcement, ensures the load on the upper part being transferred to the micro-piles. The comparison of settlement observation data before and after reinforcement shows that the proposed design method for the settlement control using the ultimate vertical bearing capacity of micro piles is safe, reasonable and practicable.