Experimental Study On Physical-Mechanical Behaviour Of Soft Clays At Chongwan Section Of Huaihe-Changjiang Waterway

The west dam of Chongwan section of Huaihe-Changjiang waterway has experienced several landslides since it was built. It is always difficult to meet the flood control design requirements for it is still setting. For more effective reinforcement to the dam, a series of physical and mechanical tests was carried out on the bad soils.The main works and innovations performed in the paper are concluded as follows:(1)The physical characteristics of the soils in Chongwan section which are 6.5 m and 13 m deep were explored. The result indicates that the soils in this part have special physical characteristics with high organic content and certain of expansibility. A series of compression-swelling tests and tri-axial consolidation undrained shear tests were performed on undisturbed soils of the soils. The results show that the soils have high compressibility, high swelling characteristic and low shear strength index.(2)A series of oedometer tests were performed on reconstituted Chongwan section soils with various initial water contents. Through the comparison with the compression curve of undisturbed soils, the effect of structural on the mechanics properties of Chongwan section soils was clarified. The Burland intrinsic compression theory and extended intrinsic compression lines were introduced in this paper. The compression characteristics of the special soils were researched. The characteristics of the normalized compression curve of organic soil were discussed. The variation regulation between intrinsic compression parameters with organic matter content of soil was researched.(3)A series of tests on artificial organic soil studied the influence pattarn of different organic matters on the physical properties of soil; analyzed the mechanism of the increasing liquid plastic limit and plasticity index with the addition of potassium humate; revealed the regularity of the increasing compressibility, decreasing permeability and extending time for consolidation with increasing of organic matter. These effects of organic matter on the physical and mechanical properties of soil impled that organic matter is bad for engineering construction and the use of engineering structures.