Applied Mechanics and Materials Vols. 170-173

Abstract: Acquiring soil’s critical load is very important when designing soil foundation and soil subgrade with overloading method. Mohr-Coulomb strength theory is combined with slip-line field theory, then a theoretic method which is practicable to analyze critical load of soil come out. Analyzed theoretically and compared with others, the theoretic method is applied to describe the relationship between internal friction angel, internal cohesion, δ, lateral pressure and critical load, which express that this theoretic method is rational. Numerical analysis is adopted which make it clear that soil subgrade’s yield zone is small when it is under the critical pressure, which approve that this theory is very close to lower limit of soil’s critical load. The theoretical method can provide useful information to engineering designers and researchers.

Abstract: Based on the results obtained by the triaxial creep test, a creep-damage constitutive model for sandstone is presented by using the damage theory and by introducing the concept of “the whole process of damage” into Burgers creep model. The parameters of the model are determined by fitting the creep test data. The result shows that the proposed model can not only describe efficiently the variation of decay and steady creep under relatively low stress condition, but also give a satisfied representation of damage behavior in accelerated creep stage.

Abstract: Bulky rock material of waste pile was composed of discarded rock and soil which was blasted and stripped from stope. It was characterized by dispersibility, complexity and variability. Shear strength index of bulky rock material was the main basis for analyzing slope stability of the waste pile. After the study on bulky rock material with different coarse grain content by indoor direct shear test, the results indicated that there was no obvious peak strength during the shear process, and variation of the shear displacement was slight in initial horizontal loading stage. Horizontal loading increased slowly and shear displacement had obvious change when shear displacement exceeded 5mm. Under the same normal stress, shear modulus G0.01 increased with the increase of coarse grain content when shear strain of specimen is 1/100. Shear modulus G0.01 of the specimen with same coarse grain content increased with the increase of normal stress, varying sensitive of G0.01 reduced when coarse grain content was larger. When the specimens with same coarse grain content were under failure, the shear modulus Gfailure was smaller than G0.01. Cohesive force c of the bulky rock material began to increase and then decrease with the increase of coarse grain content, and reached its maximum of 31.25KPa when the coarse grain content was 70%, internal friction angle increased with the increase of coarse grain content.

Abstract: By using the soil static and dynamic universal tri-axial and torsional shear apparatus, the experiment was performed on remolding saturated samples of Shan-Dong Dong-Ying silt which was prepared respectively with 0%, 5%, 10% initial sampling water content. A series of stress-controlled undrained monotonic torsional shearing tests were conducted under the same conditions of initial mean principal stress as 100kPa, initial intermediate principal stress coefficient as 0.5, initial deviator stress ratio as 0.433, but with different initial orientation angle of the principal stress at 0o, 30o, 45o, 60o, 90o. During the test the intermediate principal stress coefficient and mean principal stress were controlled constantly. The anisotropic behavior of the silt were discussed through the effects of initial sampling water content and initial orientation of the principal stress on the incremental stress-strain relations of different orientations, and the strain path. It was shown that the initial sampling water content had a remarkable influence on initial anisotropic behavior. Under the same condition, the higher the initial sampling water content is, the less obviously the anisotropic behavior is. The difference between the strain path and the stress path was obvious.

Abstract: With finite difference code Flac3D, the stability of loess slope with hidden hole at different locations has been evaluated. Failure mechanism of loess slope is also studied. Under plane strain conditions, the results of numerical simulation show that the existence of hidden hole has a direct impact on the stability of the loess slope, and sometimes decreases the safety factor. The failure of hidden hole also directly affects on the overall destruction of slope. Consequently, at the stage of loess slope design, it is necessary to carefully evaluate the stability of loess slope with hidden hole. Particularly, it is important to consider the influence of stability by the position of hidden hole in loess slope.

Abstract: It is very complex that the viscous slump particle motion. The obtained motion parameters of the viscous particles which can’t be captured by experimental facility through PFC3D, which are used to analysis the influence of the viscosity damp coefficient to the motion of it. The influence includes the peak translation velocity, peak rate of rotation of the special particle and the biggest impact force. All of which have the maximum value when the viscosity damp coefficient is 0.3, but all of which reduce when the viscosity damp coefficient is 0.5. The smaller particle is easy to suffer to the influence of the viscosity damp coefficient than the bigger particle.

Abstract: Through testing the creep characteristics of plastic geogrid under the temperature of 20°C，10°C，0°C and -20°C, we obtained the creep characteristics curve under the different temperature.In order to obtioning the creep regulations of plastic geogrid by freezing and thawing cycle , we made the plastic geogrid for10 times freezing and thawing cycle at -20°C - 20°C, the one which was tested under the temperature of 20°C until its deformation became stable. Conclusions: (1) The creep of the plastic geogrid under different temperatures is quite different, it is greatly influenced by temperature and the lower the temperature the smaller the creep value; freezing and thawing cycle have influence in creep characteristics,In the condition of freezing and thawing cycle,while the creep value get stable at the normal temperature, the creep value also increasing with the temperature getting high and decreasing with temperature getting low; (2) According to the creep regulations under low temperature and freezing and thawing cycle condition,we advance the counting method of impact factor of freezing and thawing cycle, DR and creep impact factor of low temperature FcR.

Abstract: In order to study the relationship between the design parameters of the shield machine and the strength of rock, the behaviours of rocks under the conventional triaxial compression, the complete stress-strain curves under different confining pressures of three typical rocks, i.e. granite, limestone and red sandstone, were taken out for analysis. From the curves, the values of elastic modulus E and Poisson's ratio μ were gained and the relationships between the following parameters were figured out, which are peak strength versus confining pressure, residual strength versus confining pressure, strain at peak strength versus confining pressure, and strain at residual strength versus confining pressure. According to the values and relationships, the complete stress-strain curves were divided into three parts. For each part, a constitutive equation was established by using the strain softening trilinear elastic-brittle-plastic constitutive model, and all the related parameters in the constitutive equations were also presented, which provide a theoretical foundation for the digital design of the cutter head and cutters of Shield machine.

Abstract: Anchor bolt which is one of the most important component connecting foundation and transmission tower bears the force transmitted from superstructure. At present, in the conventional design method, uplift force is only included, however, the influence of horizontal force on bearing capacity of anchor bolt is neglected. Thus, a theoretical method on obtaining bearing capacity of anchor bolt is proposed for the first time based on the third strength theory in this paper, in which the influence of horizontal force is considered. According to the third strength theory, the calculation results of bearing capacity of anchor bolt under different force are obtained. It can be seen that the cross-section area of single anchor bolt shows linear increase with the increment of vertical uplift force, at the same time, the influence of horizontal force to bearing capacity of anchor bolt is more significant with the addition of the ratio of horizontal force to uplift force, which should be attached enough attention in engineering application. And the conclusion achieved in this work can provide valuable guidance for anchor bolt design of the transmission line project.

Abstract: The collapsible loess ground treatment methods include dynamic compaction, soil replacement cushion method, lime-soil compaction pile composite foundation, pile foundation, etc. Each method has its advantages and disadvantages. The bearing capacity of collapsible loess is not lower, it is non-soft soil. The purpose of the collapsible loess ground treatment is to eliminate the collapsible at the most, few to increase the capacity and improve the heterogeneity of the foundation. In this paper, the collapsible loess foundation treatment methods are been compacted from the technical and economic factors. And the key issues of the collapsible loess ground treatment methods are discussed.