Abstract:

According to the interior stability problem of the soil-nailing wall, a global optimal algorithm, which can locate the critical arbitrary slip surface associated with the minimum safety factor, is proposed. Firstly, based on Morgenstern-Price limited equilibrium method and by considering the consolidation of soil nail, a new computation formula of stability safety factor for the soil-nailing wall is presented. Then, the disadvantages of the simple genetic algorithm (SGA) and the tabu search algorithm (TSA) are following analyzed. Furthermore, the adaptive genetic algorithm (AGA) is also introduced. Through substituting the tabu mutation operator (TM) for the mutation operator of AGA, a new type of optimal algorithm, i.e. the adaptive tabu mutation operator and genetic algorithm (ATMGA) is proposed. Applying the ATMGA into the field of soil-nailing wall interior stability analysis, an optimal algorithm for searching the arbitrary critical slip surface is established. The simulating calculation results show that: (1) compared with SGA, TSA, and AGA, the ATMGA not only has the merits of high searching efficiency and fast converging velocity but also can exactly seek out the critical slip surface and the corresponding global minimal safety factor. (2) There is a significant difference between the critical slip surface of the unconsolidated wall and the soil-nailing wall, it is also suggested that it is necessary to seek out the critical slip surface and its safe factory of the soil-nailing wall in practical foundation pit engineering.

Key words: soil-nailing wall, interior stability analysis, Morgenstern-Price method, genetic algorithm, tabu search algorithm