Based on a preliminary analysis

it is estimated that the soil layer at outer of the retaining structure could produce lateral unloading and loading stress paths. Therefore

a series of tests were performed with different lateral unloading and loading stress paths. Based on Duncan-Chang model and result of experiments

formulas to calculate tangent elastic modulus were developed for lateral unloading and loading conditions. A good agreement was observed between test data and results from finite element analyses using the previously mentioned tangent modulus model. These results show that excavation of foundation pit can be better simulated on condition that lateral unloading and loading stress paths are considered.