A Stability Analysis Method of Slopes Reinforced by Anti-slide Piles of Small Pile Spacing

The application condition of T. Ito´s limit lateral pressure calculation formula has been discussed and it is found that T. Ito´ s formula does not apply when pile spacing is too small. In this view, the limit lateral pressure calculation formula of small space anti-slide pile is set up, and the relationship between the critical ratio of diameter to spacing and the internal friction angle is analyzed. Afterwards the following conclusions have been drawn, greater the soil internal friction angle is, less the critical ratio of diameter to spacing will be, otherwise, the critical ratio will be greater. Therefore, for piles of a certain diameter, we can determine a reasonable pile distance through the critical ratio of diameter to spacing. On this basis, the mobilizing factor of lateral pressure is recommended, and the formula that reflects relationship between safety factor of slope stability and the mobilizing factor is established. By simplified Bishop´s method, the formula for calculating the safety factor is derived with full consideration of the role of anti-slide piles. Thereafter, safety factors of a slope which are reinforced by anti-slide pile set at the four different locations are calculated. The calculation shows that: When the piles are set properly at the suitable locations, better reinforcement effect can be achieved, and the critical slip surface will be deepened than that without piles.