Determination of parameters for tangent modulus method using simple in-situ test and its application in nonlinear settlement analysis on sandy soil

Foundation settlement calculation has been a hot and difficult problem in geotechnical engineering study. The difficulty lies in large differences between the geotechnical parameters of indoor tests and in-situ tests. Especially for the sand foundation and hard clay foundation with high structural strength, there is a large error between calculated settlement based on the laboratory test parameters and the actual one. The tangent modulus method based on the in-situ plate loading tests to determine the calculation parameters can overcome this shortcoming and reflect the non-linearity of foundation settlement, which is a new progress of foundation settlement calculation. However, compared with other tests, the in-situ plate loading tests have more difficulties, and it is also difficult to reflect the characteristics of deep soils. By using the systematic geotechnical test data by Riverside Campus, Texas A & M University, United States, the feasibility of the tangent modulus method for calculating the nonlinear settlement of sand foundation is examined, and then the tangent modulus method by adopting lateral pressure tests and static cone penetration tests to determine different soil layers is studied and lastly the results of loading tests on different plate sizes are verified. The results show that the calculated parameters needed in the tangent modulus method determined by the lateral pressure tests and static cone penetration tests are feasible. In addition, when they are used in the tangent modulus method to calculate the load experimental curves of different plate sizes, the calculated nonlinear curves have good consistency with experimental ones. This method is a simple and easier access to deep soil parameters, providing an easier way of the determination of the parameters of the tangent modulus method. It is of great significance in solving problems of foundation settlement calculation and in promoting