Abstract: The model for calculating catenary soil arch is established aimed at solving the problem of soil arch effect in GRPS embankment. The relevant equation is derived based on the hypothesis of plain strain and real cavity below the arch and solved to obtain the height and shape of soil arch. Several test results are compared in height and shape of soil arch and soil stress of pile top. The calculated results are in good agreement with the measured ones. The ratio of the soil arch height to the net distance between the piles increases from 0.36 to 0.72 when the friction angle of subgrade fill magnifies. The correction factor of width and space increasing from 0.3 to 1 will cause the sharp acceleration of soil arch height from 0.6 to 2.4. The difference of width and space combinations is the internal reason that researchers obtaine different soil arch heights.