Study On The Residual Strength,Immersion Strength And The Damage Mechanical Model Of The 2:8 Lime-loess

Lime-loess is a kind of material that is used on improving ground bearing capacity and diminishing collapse of loess in the Middle&West area in China. And lime also is a kind of low-priced construction material, using lime-loess cushion and lime-loess compaction pile to treat collapsible loess foundations can gain good economy effect. The significance of the study on lime-loess is great in both theory and engineering practice.The engineering application and the study on lime-loess are still far behind other branches of the homogeneous subject even though rapid progress has taken place in this area. How to explore the character of the lime-loess fully and build up an simple constitutive model for the reality project become a focus of our research.For that, through about 40 pieces of triaxial tests. And the samples is lime-loess which is make up with lime and loess of LanZhou. We found that the residual strength appears a distinctly linear relationship with the confining pressure. This law is similar to rock. Undering the period of the residual strength, the inter-structure of simples have changed radically, right now the strenth is relation to the friction of the each lime-loess mass after the cracking of the lime-loess, this paper work out a statistic formula of the 2:8 lime-loess through testing data. From the wet-dry cycling testing, we found that the strength will decrease after the lime-loess was immersed,but the strength will appear up after a few times immersion,and the strength will trend to a constant volume which is not more than its original strength. This paper explain the phenomenon by the chemical reason which is ralation to the formation of the lime-loess's strength. But because of the limited times of immersion, at last, we could only work out a conjecture that the lime-loess's strengh will grow up gradually undering repeatedly immersion, and it will stay at a constant status. In additon, we can't define it brittle materials simply, it is found that lime-loess's fragility is depended on confining pressure and water content,the lime-loess's fragility will be more evident when the confining pressure become more low. It will be fragility when the water content decrease to a certain value. At the same time, according the results, we obtained the five-phase failure process of lime-loess which is ralation to the damage and crack, and analysis several failure styles of the lime-loess in detail.Combining the results of the test above, and refering to the achievement about the damage model of the cement-soil, and amending it, and abtaining a suitable model for lime-loess at last. This model have a simple form, less parameters, so there are more possibilities to make it use to practical engineering, it is a recommended model.