Practical Nonlinear Prediction Model for Uneven Settlement of an Enlarged Levee Crest

Abstract

Pavement cracking induced by uneven settlement at the junction of an enlarged levee crest (ELC) is a potential source of risks. The uneven settlement of an enlarged levee crest is nonlinear, and the existing method cannot well depict the nonlinear characteristics. To better predict the uneven settlement, the applicability of the settlement formula for half-excavation and half-filling of the roadbed in pavement widening engineering was modified by the measured and calculated data. To improve the nonlinear characterization ability of the modified settlement formula, the parameter a in the settlement formula was nonlinearized using a new foundation coefficient under the nonlinear elastic foundation beam theory. The rationality of the new foundation coefficient was discussed. The practical nonlinear prediction model for the uneven settlement of the enlarged levee crest was presented. The physical meanings and determination of all parameters were explained. The rationality of the practical nonlinear prediction model was verified through experiments. The practical nonlinear prediction model of this paper can better characterize the nonlinear settlement characteristics compared with the literature formula. Parameter sensitivity analysis shows that under the same uniformly distributed loads, there exists a ratio that maximizes the uneven settlement of the ELC. Enlargement of the reinforcement of existing levees is widely used in China. This is because it has the advantages of convenient construction, low cost, increased stability of the old levee, and reduced traffic pressure. In 2013, as many as 614.73 km of the enlarged levees were added to the main stream of the Songhua River. For the main stream of the Nenjiang River, the enlarged levees also reached up to 167.5 km. In 2023, there were approximately 117.38 km of enlarged levees in the mainstream of the Yangtze River. Enlargement is likely to cause uneven settlement of the joint region at the levee crest, leading to pavement cracking. Uneven settlement at the levee crest is an objective risk that cannot be eliminated but can only be controlled. This study provides a practical model for predicting uneven settlement of the levee crest. This model can characterize the settlement gradient at the junction, which provides a theoretical basis for explaining the mechanism of pavement cracking at the junction. Moreover, this model establishes a connection between uneven settlement and pavement cracking, which builds a theoretical foundation for the establishment of control standards.