Applied Mechanics and Materials Vols. 204-208

Abstract: According to linear programming model of operations research, the paper optimized blending scheme of earthwork by using table operation method. List the earthwork cut and fill balance sheet, through the calculation of excavation and backfill area quantity. Determine the initial transportation scheme with minimum element method, and optimize the scheme with closed circuit method, then get the minimum amount of earthwork blending scheme. It could bring better economic benefits in construction projects by using the table operation method.

Abstract: The basic features of salt rock in China are as follows: thickness single layer, more layered distribution and impurities and others. The unstable mechanical parameters are caused by the different types and content of minerals in natural salt rock. Elastic modulus and Poisson ratio of natural samples from certain northern area in China which are compressed under different confining pressure is then analysed with the impurity content to get the relationship between them. Comparing the experimental values with the predicted calculated by Mori-Tanaka method, a linear estimation formula is proposed for the prediction of mechanical parameters suitable for practical engineering applications in this area.

Abstract: Pile foundation design has gradually used the super-long pile structure form with the port and offshore engineering construction developing towards to the direction of large-scale, deepwater, and coast geological becomes more complex, bearing stratum becomes more deeper. PHC pile is the first choice of pile foundation design form, just because it has many advantages. The former researches of pile vertical load mainly on limit bearing capacity, the calculation is reasonable for short pile and middle long pile, however, it is not reasonable for super-long pile, pile body side and tip resistance can not reach the limit when structure is to limit. This paper puts forward the calculation model of super-long PHC pile vertical load in soft clay based on vertical load mechanism analysis and experimental research on the foundation pile, and the calculated and test value coincide preferably.

Abstract: The pressure-sinkage characteristics and the shear-strength characteristics of lunar regolith are the important influence factors to the trafficability of lunar rover. The performance curves and parameters of JLU luanr soil simulant were obtained by pressure-sinkage tests and shear-strength tests in the ground gravity-environmental load (1g) and the lunar gravity-environmental load (1/6g). The results show that, for the pressure-sinkage characteristics, the compression-strength of the JLU-1 is strongest, followed by the JLU-3, and the JLU-2 is the weakest. In different load levels, the deformability index n increases as the bulk density increases. The kc increase as the state becoming more and more compact,The k of JLU-1 is the largest of all, followed by JLU-3 next, JLU-2 has the smallest.The load levels have no significant effect to the tendency of n, kc and k. For the shear-strength characteristics, the shear resistance of JLU-2 is the weakest. JLU-1 has the greatest cohesion c of the three lunar soil simulant, followed by JLU-3, the c of JLU-2 is the smallest.The c of the same lunar soil simulant in natural state is greater than it in soft state. Compared with JLU-1 and JLU-3, JLU-2 has the smallest internal friction angle .The influence of the load levels to the the cohesion c internal friction angel is not obvious. The  mesured in the lunar load is wider than it in the ground load. This study will supply fundamental reference and foundation on the research and optimization of the lunar rover traveling mechanism in the authentic lunar environment.

Abstract: Based on the saturated-unsaturated seepage theory and considering soil-hydraulic permeability coefficient characteristic curves of rock slope, the variation of suction in unsaturated region and transient saturated zone formation of rock slope were analyzed. Combined with engineering example, the strength reduction methods were adopted to analyzing the rock slope stability influence factors considering unsaturated seepage with different rainfall intensity and duration. The results show that the flow domain owing to rainfall infiltration mainly appears surface layer region of slope. The rainfall infiltration caused the groundwater level rise, the rising of transient pore water pressure and the fall of suction in unsaturated region caused the slope stability decrease. The rainfall intensity and duration have obvious influence on slope stability, and in the same rainfall duration condition, the safety coefficient of slope decreases with the accretion of rainfall intensity. With the rainfall duration increasing, the water in soil has more deep infiltration, the water content and pore water pressure was higher in the same high position, the decreasing of suction caused the safety coefficient of slope has more reduce.

Abstract: In this paper, it proves that the necessary and sufficient condition for the potential sliding body reaching the ultimate limit equilibrium state is that the summation of shear stresses along the sliding surface equals to that of resistant shear strength. Based on the rigorous theory analyses and derivations, it is clearly shown that the definition of factor of safety (FOS) in the slip surface stress method (SSSM) is irrelevant with the shape of slip surface. Thus, the authors demonstrate that the FOS of noncircular slip surface can also be defined as the ratio of the sum of resistant sliding force along slip surface to that of sliding force. Furthermore, the physical meaning of the FOS in the SSSM, which can be taken as the average evaluation of the strength reduction coefficient that makes the sliding body reach the ultimate limit equilibrium state along the slip surface in nature, is formulated on the basis of strength reserving theory rather than the overloading theory like that in the Limit Equilibrium Method (LEM) and the Shear Strength Reduction Method (SSRM). Finally, the factors of safety (FOS) and the locations of critical failure surfaces obtained by the SSSM, LEM and SSRM are compared for various geotechnical practices. It is found that the SSSM can achieve precise and reasonable stability assessments for the soil slopes on the basis of actual stress field. Consequently, compared with the LEM and SSRM, the SSSM is demonstrated to be effective and efficient alternative approach for routine analysis and design in geotechnical engineering practice with a high level of confidence.

Abstract: On the basis of the measured ground borne vibration of some inter-city express railway viaduct, test results analysis shows that: the test environmental vibration is under the limit set by standard of environmental vibration in urban area; whether transverse or vertical vibration, a rapid attenuation of the peak acceleration with the distance to the up-track center is observed, however the vibration at 7.5m appears to be amplified; the ground vibration with the distance conforms to a logarithmic relationship; the horizontal ground vibration at 7.5m caused by the elevated rail transit is larger 3.6cm/s2 than the vertical vibration; low-frequency vibration transfers farther than high frequency vibration; the eccentric effect of two-track viaduct is obvious.

Abstract: In this paper, triaxial compression experiments on remolded soil were carried on by simulated the stress path of vacuum preloading method. With Industrial Computer Tomography(ICT), the pore micro-structure in soil samples on different load phases were studied. The number of pores was decreasing in trend, and pore area gradually became smaller. Shape factors gradually became larger, and the pore shapes were rounded. Direction angle tends to unity, orientation become better. In addition, the relationships between compression and pore surface area ratio, strength with deformation , pore size with shape factor, permeable nature and pore orientation in vacuum preloading process were established.

Abstract: The three-dimensional roughness characteristics of the tensile granite joint surfaces are studied. Firstly, the tensile granite joints are prepared by splitting cubic granite blocks, and the triangular networks of the joint surfaces are established based on the topographic data collected by laser scanner. Then, the roughness characteristics of the two-dimensional profiles in different positions and different directions are studied. It proves that the roughness of the tensile granite joint surface is position and direction depended, and the roughness parameters based on the profiles are inadequate to characterize the roughness of the three-dimensional joint surfaces. Some new roughness parameters to characterize the three-dimensional joint surfaces are finally calculated on the basis of the triangular networks, these parameters can reflect the spatial and anisotropic characteristics of the joint surfaces. The results in this paper will lay the foundation for further study of the roughness characteristics and mechanical properties of the tensile rock joints.

Abstract: The stability of the landslide can be effectively evaluated and predicted by predicting the future development of landslide deformation according to the actual deformation of the landslide. Therefore, the accuracy of the prediction regarding the landslide deformation determines the validity of the landslide stability assessment. The GM (1.1) model in the grey system theory, uses displacement time series to establish the grey differential equation. By solving the equation, we can obtain a time response function, which can then be used to predict the landslide deformation. The BP neural network is a used for training and exercising on the deformed samples. After the error meets the requirement, we can then use the trained model to predict the landslide deformation. This paper use both grey system theory model and BP neural network model to predict Jinlong ditch application field landslide deformation.The prediction results are compared and analyzed to test the accuracy of these two predictions. Finding a more accurate prediction method for application in actual engineering project has practical significance.