Experimental Study And Simulation On The Mechanical Behavior Of Coarse Grained Soil

The coarse grained soils have been applied widely in the earth-rock dam engineering. But the coarse grained soils which are used in different parts of the earth-rock dam have different engineering properties. For example, the rock which has strong hydraulic conductivity is often used as dam shell materials. And the gravelly soil which has weak hydraulic conductivity is often used as impervious core. The study on the different coarse grained soil's engineering properties become more and more important. Otherwise, in the earth-rock dam's FEM, Duncan-Chang model is widely used. But it still needs to be proved that weather it can reflect the coarse grained soil's stress-strain characteristics and weather it can adapt the real stress path in the earth-rock dam. According to these questions, some work has been done in this paper.First, from an earth-rock dam's FEM results, we can find out that the stress path in the dam is principal stress ratio keepping constant during the dam's constructing time.Second, a series of UU tests for three kinds of unsaturated gravelly soils with different coarse material content (P5) and different water content are performed. From the test results, we can know that it will reduce the gravelly soil's deformation if P5 increase and it will reduce the gravelly soil's strength if water content is increased. According to the stress path of dam, the corresponding tests are performed. Analyzing the test results, the Duncan-Chang model can basically reflect the coarse grained soil's stress-strain relationship under the stress path of dam.Third, a series of CD tests for dam shell coarse aggregate are performed. The coarse aggregate's stress-strain characteristics are analyzed according to the test results. And same to the gravelly soil, some stress path tests for coarse aggregate are carried out. From the test results, we know that the most of the dam shell's deformation during the dam's constructing time is consolidation deformation.Finally, according to the coarse grained soil's test results, it can determine tangent modulus by using Duncan-Chang model. But Duncan-Chang model is not able to properly simulate volumetric strain behavior of the coarse grained soil. A modified model of coarse grained soil is then developed through presenting new volumetric strain assumptions according to the test results. The validity of the modified model is preliminarily confirmed in predicting the volumetric strain response of coarse grained soil by triaxial compression test results of several kinds of coarse grained soils.