Experimental Study On Inlfuencing Factors To The Wetting Deformation Of Earth-rock Filled Dam Under Constant Pressure

The problem of hydraulic fracture in core wall of earth-rock filled dam is paid widelyattention as it influences the safety and stability of dam directly. Indeed, the fracture anddefect of the core wall is the basic material condition and the premise of the hydraulicfracturing. The construction process and uneven settlement is considered the two main factorswhich can explain the fracture at present.Based on the theory of unsaturated soil, constitutive relation changes with the variationof saturation. In the water storage stage especially for the initial storage, with theimprovement of water saturation in the core wall, the stresses of core wall in different partsare various and the deformations are different as well.In this thesis, conventional odometer cell under a series of constant confining pressuresis used to simulate the compacted unsaturated clay soil in the dam and then the wetting loadsimulates the stage of water storage. The influence of pressure, void ratio and watersaturation to the wetting deformation is analysed according to the tests and the conclusionsare listed as follows:(1) The time of saturation process will be affected by the permeability.(2) The deformations of saturation process under different pressures are different.(3) The void ratio plays an important role on the wetting deformation. For the lowpressure (50kPa to200kPa), specimens expand and the amount of expansion is reduced withthe increase of void ratio. For the high pressure, specimens are compressed and the amount ofcompression is increased with the improvement of the void ratio.(4) It also shows that water saturation at a certain range has a significant influence on thewetting deformation. From deformation curves of specimens under compress stress from100kPa to200kPa, it can be seen that the constitutive relation changes obviously when thewater saturation ranges from60%to70%.(5) The water saturation has a great influence on constitutive relation of this clay soiland it is influenced by the void ratio and moisture content. So the influence of water saturation to the constitutive relation of soil can be studied form these two factors.(6) The various deformation character of the core wall in the saturation process may leadto the fracture and defect, and this maybe give us a new explication of the cause of the initial faultnecessary for the hydraulic fracturing.