| Cracking of the high arch dam heel will directly reduce its integrity and stability.After cracking,the effect of high-pressure water is easy to cause hydraulic fracturing.Therefore,it is of paramount importance to study the cracking pattern of dam heel and to improve its crack-resistance ability for the engineering safety.Based on Deformation Recinforcement Theory（DRT）,geomechanical model test and numerical simulation are conducted to mainly discuss the evaluation of high arch dams’cracking mode and the reinforcement effect of foundation treatment.Besides,the numerical method simulating dam heel hydraulic fracturing and the mechanism of hydraulic fracturing of the block s made of analogous-material are investigated as well.Some major achievements are listed as below:（1）Several key zones along the arch dam’s foundation surface are choesed to evaluate the risk level of them.The changes of each zone’s yield volume could reflect its damage potential.Due to the good match between the crack initiation location in model test and the dam heel unbalanced force,the value of unbalanced force under 1.5P0（which is also the overloading factor of the crack intiation）is used as a quantitative indicator to e valuate the dam heel’s crack-resistance ability.The results of model test agree well with the numerical calculation,which verifies the effectiveness of the prensented method.（P0 is the water load under normal working condition）（2）Three indicators which include increasing dam’s global stiffness,reducing the fault’s yield volume and improving the anti-sliding stability are proposed to evaluate the effect of faults treatment under normal working condition.C onsidering the limitation of the currently-used method to calculate the fault’s replacement depth,the initial unbalanced force is used to determine the treatment depth.A sensitivity analysis is conducted to verify that the depth determined by the initial unbalanced force is the optimal treatment depth.（3）The features of yield zone expansion along the foundation surface of Mengdigou arch dam are summarized.For the phenomena such as yield zone appearing at dam heel under normal working condition and its fast extension,the influence of foundation treatment and fillet is explored.It is proved that the foundation treatment has no obvious impact on yield zone expansion process.The fillet can significantly reduce the yield area of the dam heel under 11.5P0,however,it makes no evident difference under high overloading condition,which is also validated by engineering analogy method.（4）Fracture water pressure is taken into consideration in the yield function of elasto-plastic model and applied in the elements near dam heel in order to simulate the effect of hydraulic fracturing.Based on that,the fracture problem can be studied using continuous method.The effects caused by fracture water pressure on dam displacement,dam heel’s cracking potential and yield zone are discussed.（5）Physical experiments which simulate hydraulic fracturing of blocks made of analogous material are performed to investigate the influence of parameters such as the length and angle of pre-made transverse notch on the initiation and propagation behavior of hydraulic fracture.The assumption of physical experiments is verified by the numerical simulation. |
