A Model Test Study Of The Distribution Of Additional Stress And Ultimate Bearing Capacity Of Meadow Soil Foundation Under Embankment

The meadow soil foundation is a special type of soft soil foundation, which distributed widely in China, especially in the western and northeast area. With the process of the Great West Development and Northeast Area Revitalization, it is inevitable that the meadow soil foundation would be met in the highway construction. Previously, due to the lack of intensive analysis and the research for the meadow soil foundation, it is not easy to distinguish the meadow soil from the peat soil. Besides, the treatment methods for the meadow soil foundation cannot be chosen appropriately during the construction. Nowadays, most of the meadow soil foundations are treated according to the common soft foundation, and although there are some successful cases of constructing embankment on the top of the meadow soil foundation that without any treatment, however, it is just based on the experience instead of theoretical guidance.Combined with the meadow soil in Xinjiang reclamation corps and based on the normal indoor tests, laboratory model tests and theoretical analysis, this paper makes a research about the physical and mechanical properties of the meadow soil and the distribution of additional stress as well as the ultimate bearing capacity of it. The main findings are as follows:1. Based on the normal indoor tests, the physical and mechanical properties (such as specific gravity, water content, permeability, loss on ignition, shear strength, unconfined compressive strength, compression characteristic, and consolidation properties) of meadow soil are analyzed. Besides, the position of meadow soil in engineering field has been cleared and the differences of engineering properties between the meadow soil, the peat soil from Yunnan, Hangzhou and the Jilin turfy soil have been analyzed.2. According to the physical mechanical properties of meadow soil and the criteria of the similarity theory, the alternative material for the meadow soil has been studied, which lays the foundation for the model test. The fuzzy theory method has been used for testing the degree of the similarity.3. Two kinds of soft soil foundations have been used for testing the influence of the meadow layer to the foundation settlement and the distribution of additional stress. The soft soil 1# was used for the test of uniform soft soil foundation and the 6cm thickness meadow soil foundation; the soft soil 2# was used for the test of uniform soft soil foundation and the lcm,3cm,6cm thickness meadow soil foundation. The vertical additional stress distribution law on the top of soft soil has been studied by the methods of regression analysis and the theoretical revision.4. The present formulas for the ultimate bearing capacity of layered foundation have been compared. Then, the formula for the ultimate bearing capacity of the meadow soil foundation has been provided based on the formula for the ultimate bearing capacity of the hard crust foundation. The results by using various formulas have been contrasted.