Abstract: The plate loading test is considered as the most wide and reliable method for determing bearing capacity, However, it can be affected by many factors, for instance, the size and buried depth of the load plate, the homogeneity of the soil, the criterion of determining ending of settlement, among which the size of load plate is the most important one. Mass engineering projects show that relatively error can be found between monitoring and predicted settlement when the plate load test is applied for determining the bearing capacity of foundation. Due to the above-mentioned problem, the paper considers the size effect of plate load test and the method for determining bearing capacity based on previous studies by others. The contents include: (1) Summarizing the defects of currently used methods for bearing capacity determination. (2) Analyzing the size effect of load plate. (3) Deriving the method of obtaining the p-s curve for real foundation by plate load test with plate in small size, based on Professor Yang’s theory of nonlinear tangent-modules method. (4) Proposing the method for determining the bearing capacity based on the p-s curve of the real foundation, the method is able to guarantee the safety of foundation and predicting the settlement. (5) Due to the fact that the plate load test is normally used for soils in shallow depth, the paper proposes a method to determine the bearing capacity in deeper soils by pressuremeter test; A project results show that the settlement calculated based on the soil parameters derived from small-size load plate test is closer to monitoring data. The research on deriving soil geotechnical parameters through small-size plate load test not only improves the accuracy of settlement calculation, but also promotes the development of foundation design theory.

Key words: plate load test, size effect, bearing capacity, tangent-modules method