Research On Mechanical Test Of Maokou Limestone Under Osmotic Pressure

The mechanical properties of rock mass in the seepage field and permeability properties of rock mass in the stress field have become one of important topic concered with rock mechanics discipline. In the filed of fluid-structure interaction, on one hand,the internal stress of rock mass is redistributed for the role of external load, which had an effect on rock mass structure and changed the role of water intensity, scope and form; on the other hand, the internal structure of rock is closely related to the stress state,which has a inflounce of seepage path.There are important guiding significance and broad application prospects of fluid-structure interaction to mining engineering, water resources and hydropower engineering, tunnel engineering etc.Based on the national natural science fund projects, fluid-structure coupling experiment of Maokou limestone were conducted, strength characteristics, deformation characteristics and seepage characteristics and failure characteristics of them which are under different confining pressure osmotic pressure are researched. and the change mechanism of various features are revealed. Main research content are following:(1) The intensity values and parameters of the rock were calculated. The effect of confining pressure and osmotic pressure on Maokou limestone’s peak strength, splitting strength and damage strength, shear strength and its parameters, the deformation characteristics and deformation parameters, failure characteristics are analysised. The change mechanism of splitting strength in Maokou limestones which are under the action of osmotic pressure are discussed.(2) The evolution of osmotic pressure differential are studied, and it is divided into four stages during the progressive failure process. Permeability properties of Maokou limestones that are under different confining pressure are observered,. What’s more, the relation of permeability and volume strain is established on the basis of Kozeny- carman equation, and test dates were applied into the theory model to verify the applicability.(3) The rock strength criterion which considered osmotic pressure is proposed through referencing weakening pore pressure coefficient, and the comparation of new strength criterion with others is conducted to verify the applicability and accuracy.