Although numerical simulation is the prominent method for calculating earth pressure on the foundation pit, it is not handy to do calculating whenever and wherever possible as analytical solutions do. An analytical solution of earth pressure is performed to estimate the mechanical response of backfilled openings, emphasize the effect of load transfer along the interface at the corner of foundation pit. The arc between adjacent corners of pit is formed as parabolic whose original rake ratio at corner can be determined as a function of friction angle in soil. Based on the formation of stable arch in soil, a sliding block behind retaining structure can be determined as a parabola prism truncated by sliding plane. Finally, a formula of active earth pressure is deduced in light of limit equilibrium theory. The results indicate that the arching effects developed in the backfill greatly influence the resultant force on the supporting structure. The analytical results are compared to experimental ones and the discussion that follows highlights some of the key factors influencing the resultant force on the supporting structures.