Abstract:

One of the slope treatment measures is the replaced-backfilling clay treatment in the Luwangfen test region of middle-route of South-to-North water division project. The engineering property of replaced-backfilling clay is studied by physical test, compaction test, expansive property test and in-situ test. Studies show that: (1)the diversity of particle component of it is obvious, in which sand grain and silt are dominant, gravel is lesser, cosmid and colloidal particle are least；(2)the optimal water content of replaced-backfilling clay is 17.7 % with the corresponding maximum density of 1.71 g/cm3 under the condition of light compaction, the optimal water content is 18.4 % with the corresponding maximum density of 1.87 g/cm3 under the condition of heavy compaction；(3)the specific gravity of replaced-backfilling clay is 2.7, liquid limit is between 37.6 %－38.7 %, plastic limit is between 17.1 %－19.2 %, plasticity index is between19.4－21.2, therefore, it belongs to low liquid limit clay；(4)when the sample of replaced-backfilling clay is selected within the depth of 3.5 m, the free expansive rate is within 40.0 %, which means there is no expansive potential; when the sample is selected between the depth of 3.5－4.5 m, the free expansive rate is between 42.0 %－76.0 %, which means there is middle or weak expansive potential; (5)there is no obvious relation between ( ) of replaced-backfilling clay and depth, but the module parameters of it has the decreasing tendency with the increase of water content. The result provide scientific reference for the application of replaced-backfilling clay to the middle-route of South-to-North water division project.

Key words: South-to-North water diversion, replaced-backfilling clay, engineering property