Applied Mechanics and Materials Vols. 204-208

Abstract: This article presents a comparison and analysis between piezocone penetration test (CPTU) and laboratory test in identifying soil stratigraphy of Shanghai. In China, stratigraphy for soft deposit is mainly obtained from plasticity index and grain size distribution of borehole samples in the laboratory (refer to code method). Identification of soil stratigraphy with CPTU was developed and improved in recent decades. The analysis is carried out with the field data at test site of Yan’an Road Tunnel in Shanghai. The stratigraphy charts proposed by Robertson in 1990 (refer to Robertson charts (1990)) are used to identify soil strata. The results are comparison with that from the code method. The results show that Robertson charts (1990) can be suitable to identify the stratigraphy of soft deposit of Shanghai. Moreover, the discussion on discrepancies between them is also conducted.

Abstract: The dynamic testing is widely used in undestructive testings of bolt’s anchoring quality. But it’s difficult to estimate bolt’s anchoring quality according to the dynamic response of bolt. The bolt’s anchorage quality depends mainly on bolt-surrounding rock structural system which features must be identified. A new analytical method used in identification for bolt-surrounding rock structural system is put forward, which combine with advantages of wavelet analysis and artificial neural network. The results indicate that this wavelet neural network after training can best identify the bolt’s side rigidity factors and can be a useable intelligentized mean to assess the quality of bolt’s anchoring system.

Abstract: The cast-in-situ concrete pipe pile is a new kind of pile used widely in China to improve the soft ground. In this paper, the general introduction of this pile was given, mainly including the pile driving machine, the technique of pile working and the structure of pile. At last, one in situ test of this pile under lateral load were given, the characteristics of displacement of pile body and displacement of pile top were analyzed. These results can give a reference for practice project.

Abstract: The article puts forward a single-rammer energy calculation formula based on pseudo-static method which is to be applied in the dynamic compaction trials of saturated soft soil foundations. A comparison between the formula and the dynamic compaction effective reinforcement range formula is made. Then, data from actual engineering project are applied to the formula, and the calculated results are consistent with the testing results. That is to say, the formula can facilitate the forecast of single-rammer energy in dynamic foundation compaction.

Abstract: In geogrid-reinforced and pile-supported composite foundations, the piles, grids and soil compose a complex system in which the three parties perform in coordination to bear the loads. The service behavior and functional mechanism of the geogrids are explored through static and cyclic load tests.

Abstract: Sine wave loading experiments are carried out on MTS for pump-oil saturated Nanjing sandstones and water saturated Dali marbles. The Young’s modulus and velocities of longitudinal wave and transverse wave increase with the frequency, and there are notable dispersions. The existence of micro defects in saturated rocks result in hysteresis at the sinusoidal loading experiments. The variation curves of instantaneous Young’s modulus with stress for loading and unloading intersect, and an “X” shape figure is obtained. As the frequency of the sinusoidal wave increases, the position of the intersection point moves to higher modulus area. Thus the modulus dispersion increases. Some physical mechanisms of nonlinear frequency response of rock are revealed. The results obtained are very important for nonlinear wave study, and the theoretical study and application of earthquake and engineering.

Abstract: Based on the experimental study of the gravel layer under the level of vibration load, we analysis microscopically the dynamic response in the gravel pile and the variation of energy dissipating rapidly along the depth of granular structure. Propose that the main reasons of the energy dissipation are scattering and shear resistance. Based on the stochastic theory, we have derived the model of probability which reflects the dynamic response of the particles under the action of horizontal vibration. It has provided a theoretical basis for study on the characteristics of the energy dissipation and damping in granular structure.

Abstract: The homogenization technique has been used to derive equivalent material properties of masonry for many years, however, very few studies by most previous researchers concerntrated on the strain state of RVE, which is very important to calculate the equivalent material properties in the finite element modeling. In this paper, periodic boundary conditions is established automatically with the python re-development produce in ABAQUS environment, and is used to simulate the stress-strain relationship of RVE in different load cases based on ABAQUS. Equivalent elastic constants is derived and make a contrast to other researchers. The results indicated that the periodic boundary conditions derived in this article is feasible, and a reference is made for the finite element modeling of RVE.

Abstract: Frame theory plays an important role in signal processing and image processing. The shearlets provide optimally space representations for 2D functions that are smooth away from discontinuities along C^2 curves. In the note, a new sufficient condition for irregular shearlet frames is presented. This provides a theoretical foundation for the applications of shearlets in the engineering.

Abstract: A unifying section problem of a double circuit power transmissions tower (DCPT)’s chord member was studied in this paper. The collision between the theoretic analysis and practical process in optimization of unifying section was proposed. The bourn of each chord member’s broken position was taken into consideration. The concept of dynamic programming was cited, and a procedure to get all the feasible combination patterns for unifying section was put forward by recursion. The object function which is the combination of the decision making and the state in every phase was set up. The object function value of whole structure can be obtained based on the previous decision of every phase. The optimization value in a decision of the weight of the tower’s chord member was set up though above object function value in a certain combination. At last, the optimization solution is designed via selecting a series of self calling functions on the basis of recursive idea.