The Application Of Nonlocal Friction Model In Analsis Of Soil

In the practical research and analysis of geotechnical engineering, the Coulomb's friction model is usually used to analyze the contact frictional problem between two jointed rock. But in this theory it is thought that the friction stress at one point on the contact surface depends only on the stress state on this point. So the result based on the classical Coulomb's friction law and the results in practical project were always significantly different. However, a number of the theories of nonlocal field indicate that the friction of contact surface at one point depends not only on the stress state on this point but also the other point nearby. That is to say that there are nonlocal effects between the contact surfaces.In this paper, the nonlocal friction law proposed by Oden et al is applied to analyze the shear stress of the tension pile between the pile and the soil. Then the range of influence of features radius of the nonlocal model is discussed. The study shows that the growing trend is cardinally identical. Only that the shear stress peak values where are on the top of the tension pile are different. And we can find that the nonlocal effect is less obvious along with the growth of depth of the pile. Besides, the deformation of the pile is analyzed by using the nonlocal friction model based on the geometric model of the tension pile. The results are compared with that based on local frication model. It shows that the deformation of tension pile based on nonlocal model is smaller than that of local model. When the uplifting load is on peak value, the different is the largest.Based on nonlocal friction model, the nonlocal effect between retaining wall and soil is studied. The lateral earth pressures based on nonlocal model whose integration area is not only symmetrical but asymmatric is calculated and analyzed. The results are compared with those obtained by local frication model and Coulomb's earth pressure theory. It indicates that the results obtained by nonlocal frication model coincides reasonably well with the experimental results. So we get to know that the nonlocal frication model introduced to analyze the lateral earth pressures of retaining wall is of practical significance. As we all know that the resist slippery strength of the retaining wall is support by the friction between the retaining wall foundation on the anti slide calculations of retaining wall. So in this paper the nonlocal frication model is introduced to analyze the nonlocal frication effect between the foundation of retaining wall and soil based on the hypothesis of retaining wall's sliding plane that is pillbox distribution. Then the positive stress and shearing stress between the bottom of the retaining wall and the soil is worked out by using minimum potential energy principle. And the nonlocal effect as well the features radius of the nonlocal model is discussed. The results show that the shear stress peak values are more or less the same. Furthermore, the nonlocal effect is the most obvious when the nonlocal features radius are different. And the position of another zero point of the parabolic slippery presplit face which is differ from the origin of coordinates has obvious distance, which moves outwards. That is to say the range of the slipping and splitting section in practical engineering is bigger than the theoretical calculation results. Then the relation between the size and location parameter of the parabola and the safety factor of the retaining wall which is anti horizontal slip is analyzed, and the value scope of that parameter is given based on rules. So this can provide reference for engineering design.In this paper, based on the gradient dependent nonlocal friction model, the slope stability is analyzed and the positive stress on the sliding plane is proposed by using minimum potential energy principle. Besides, the shearing stress is obtained. The relationship between the dynamic parameters and safety factor of slope stability is studied. And the influence of safety factor of slope stability on change of the cohesion and inner friction angle of the soil is researched and analyzed. From the result we can know that the dynamic parameters have influence on the safety factor of slope stability. In addition the safety factor of slope stability is more sensitive to change of inner friction angle than the cohesion.