Abstract: The soil piece with finite width between the adjacent foundation pits in synchronous excavation is different from the one adjacent to existing building foundation pit. Their destruction direction is unknown, the destruction forms are various. Therefore it is difficult to apply the existing methods to calculate the active earth pressure on both sides of the soil piece. The silo balance principle is intruduced. By the mechanical equilibrium analysis and solving differential equation, a formula is developed for calculating the active earth pressure on the supporting structure installed on both the sides of soil piece (sand and clay) with a finite width. The formula has fewer parameters, less conditions and is convenient to use. By comparing with results from the Rankine active earth pressure calculation formula and the finite element simulation, it is found that the results by proposed procedure are consistent with those by Rankine’s method and finite element simulation. But the earth pressure by this paper is far less than Rankine earth pressure at the same depth.

Key words: soil piece stability, finite width, adjacent foundation pit , synchronous excavation, active soil pressure, FEM, silos