Advanced Materials Research Vols. 1065-1069

Abstract: Most of slopes in nature have three-dimensional characteristics, such as displacement field, sliding surface, and mechanical mechanisms. Slope monitoring should take the three-dimensional characteristics into consideration to make monitoring networks arranged reasonably. In this paper, the Lijiazhai high slope on Shi-Ji highway is taken as engineering prototype. A similarity material of high density, low elastic modulus, and low intensity is produced. The deformation and failure characteristics of the high slope under moderate, heavy, and Torrential rain are simulated. The results show that the deformation of Lijiazhai high slope has obvious three-dimensional features. On bases of the model test, operational guidance and advice for long-term monitoring are provided.

Abstract: The theoretical calculation of PHC pipe pile negative friction resistance is difficult to obtain valuable results due to many complex factors involved, such as soil properties, consolidation conditions and actual working environment, so the field monitoring is the only feasible method. The pile negative friction resistance can be got by pre-buried sensors inside the pile to monitor the changes of stress and strain of shaft. However, for PHC pipe pile, the sensors can not be embedded and protected effectively in the process of pile manufacturing, which makes the negative friction resistance of PHC pipe pile become a very thorny problem. Based on the improved field monitoring method and data analysis of sliding micrometer technology, a new method was introduced into the PHC pipe pile negative skin friction resistance testing in this paper. We can got not only the PHC pipe pile negative friction resistance, distribution range and neutral point position with different load or time, but also the strain distribution, axial force distribution, skin friction resistance and toe resistance distribution of pile, etc. The practical engineering application shows that the new method is very effective to monitor PHC pipe pile negative friction resistance and very beneficial to further research on formation mechanism and theoretical calculation of negative friction resistance of PHC pipe pile.

Abstract: To research the deformation regularity of loess tunnel in reserving core soil with annular excavation method compared with other construction methods, 3D Numerical Simulation is applied and the loess tunnel of highway is taken as an example. The research results show that[1]：The deformation of surrounding rock affected by the area of core soil is small.The stress regularity of different support structure influence on the area of core soil is different. This is mainly reflected that the maximum pressure stress of primary support increases with the area of core soil’s increasing, but the minimum bending moment of secondary lining is not appeared in the working condition which the minimum core soil area is.

Abstract: By biaxial test of soil particle flow simulation program, the corresponding relationship between macro and micro parameters were obtained firstly. And then the slope model was established accord with these parameters. With this model, the slope stability under load were analyzed numerically, the influences of applied loading area on slope stability and damages were compared. Results shown that a slip surface came when slope was broken under a few loaded area, which is called the main slip lines. With the movement of the sliding, other landslide cracks began to appear; when subjected to a large load area, the slope undermining the main slip line was not obvious, but there were multiple landslide fissures, along with the movement of soil, the speed of slope failure increased, and severely damaged instantly.

Abstract: According to the rock high-cut slope excavation engineering practice of a substation in Jiangxi, with the goals of stable and economic rational slope design, numerical simulation research of the slope ratio and unloading platform and design optimization work was carried out. The slope safety factor, displacement and plastic zone distribution changes of different slope ratio and platform setting programs were obtained. The results show that:(1) the adjustment of the slope ratio and platform can significantly affect the slope displacement and plastic zone distribution, reasonable slope ratio and platform can reduce the horizontal displacement and plastic zone of slope, increase the safety factor and stability;(2) the slope monitoring results show that numerical simulation optimization design is feasible, and the excavation slope maintain security and stability during the construction period, and economic benefit has been obtained. The research conclusions can provide technical support for the engineering design, and reference for design and research of high-cut slope excavation engineering with similar conditions in that region.

Abstract: The stability of rock masses is controlled by the shear behavior of rock discontinuities, and it is hard to investigate the shear behavior of rock discontinuities at micro-scale by using traditional physical test method. With this in mind, Particle Flow Code is used to simulate the direct shear test of rock discontinuities. The PFC model of rock discontinuities is established firstly, and its micro-properties are inversed by using the proposed optimization inversion method based on the asynchronous particle swarm algorithm. Then, the PFC simulation of shear behavior of rock discontinuities is performed. The simulation results show that the number of microcracks gradually increases with the increasement of shear displacement, and the accumulated microcracks result in the shear failure of rock discontinuities.

Abstract: Preloading method is a common way to dispose large-scale soft soil foundation, and its methods of calculating the settlement amount mainly include exponential curve method, hyperbolic method, and Asaoka method. This paper chose exponential curve method and hyperbolic method to conduct ultimate settlement calculation on some reclamation project of Yingkou Port against measured data of settlement in the project, and compared the result to that calculated by splitting summation method. The accuracy was also verified by measured data of settlement amount in later phase to reach the conclusion that hyperbolic method is more suitable for calculating the ultimate settlement amount considering the soft soil foundation of marine facies in Liaoning.

Abstract: Saline soil is widely distributed in Jilin seasonally frozen zone. Many engineering hazards are associated closely related to moisture migration with freezing-thawing cycles. Soil salinization in the region is mainly due to migration of soil moisture and salinity caused by the temperature gradient with soil freezing process in this area. Adopt self-developed experiment instrument for measuring the freezing experiments of saline soil in Sanzhigou. Constract and analyze the transformation of moisture content and soluble salt before and after the freeze, and quantify the moisture and salinity substance migration in the freezing process.

Abstract: By taking practical engineering cases as an example, this article judges the safety distance affected by ultrahigh energy dynamic compaction. Through the organization and analysis of the data of several ultrahigh energy dynamic compaction projects, the opinion that the judgment method of vibration acceleration exists flaws is proposed. Considering the possible influence of dynamic compaction vibration on person and other non-buildings, it suggests to use the method of vibration velocity to judge affected safety distance.

Abstract: Consideration of radial inhomogeneity of soil, an analytical solution to horizontal vibration of pile in radial inhomogeneous soil is deduced, and the parameters influencing the horizontal vibration characteristics of the pile in radial inhomogeneous soil is analyzed carefully. The number of the radial layers of the inner soil, the thickness of the inner soil, the weakened degree and the ratio of length and radius can obviously affect complex impedance of the top of the pile. Before analyzing horizontal vibration of pile, choice a reasonable number of the radial layers of the inner soil and proper thickness of the inner soil, which is crucial. The more is the weakened degree of the inner soil, the stronger the fluctuations of horizontal vibration of pile are. The ratio of length and radius can influent horizontal vibration of pile within a certain range.