Aiming at the lack of the current determination method for voids in practical engineering applications

in order to accurately quantify the voids beneath cement slab

the determination method was proposed with slab edge  slab center deflection difference and slab corner  slab center deflection difference in the same cement slab for voids.Threedimensional models were set up using the ANSYS finite element method for voids beneath slab corner and slab edge.And the load was simulated with FWD test results.Thereafter

the deflection values were calculated in slab center

slab corner

slab edge under different void depth

void area and load transfer capacity.And the range of deflection diffidence was obtained.With YantaiWeihai expressway

detection data for deflection using Falling Weight Deflectometer were statistically analyzed.And the criteria and correction factors of load transfer capacity were given with simulation and samples analysis.The feasibility of criteria was verified by actual test data.It is found that the simulation values and the test values are in good agreement.The accuracy of void determination by lab edge  slab center deflection difference and slab corner  slab center deflection difference are 88.5% and 84.6%

respectively

which meet the engineering requirements.The voids were determined under the same conditions with the elimination of deflection variability.