Applied Mechanics and Materials Vols. 405-408

Abstract: Based on Vesic theory of cavity expansion and Mohr-Coulomb yield criterion,A method was proposed which can be used to calculate earth pressure around circular section static compaction pile.Furthermore, a formula calculating earth pressure around circular section static compaction pile with horizontal displacement was deduced based on hyothesis without relative displacement on pile-soil contact boundary.Finally,according to the research above and force balance condition,an estimation method for horizontal bearing capacity of circular section static compaction pile was gotten.In order to validate the feasibility proposed theory in this paper, a comparative research was carried out.Both experimental and theoretical results indicated that earth pressure on pile-soil contact surface of soil compaction pile was much more than of pile without soil compaction and earth pressure would redistribute with change of horizontal displacement.Moreove,because horizontal bearing capacity calculated by method in this paper accorded with result measured in field very much,the theory in here was feasible.

Abstract: To the instability of acoustic emission (AE) signal of rock fracture, the method about feature extraction and comprehensive recognition of those was came up with combining AE parameters, EMD and BP neural network. Through the acoustic emission experiment of different brittle rock under uniaxial compression, stress-strain curve and AE data were obtained; time-frequency characteristics of AE signal of rock samples were compared. Feature vectors, like AE parameters, and EMD energy entropy, was synthesized to BP neural network to distinguish different AE signal. The results show that evolution characteristic with stress or time of AE parameters of different rock which was under uniaxial compression exist similarities and differences. EMD and Welch spectrum can reflect the difference among spectrum, energy distribution of AE signal of different rock very well. With various characteristics of different rock acoustic emission, the neural network has good recognition effect.

Abstract: A new method that is to use soilbag filled with sludge instead of using jackstone has been proposed to construct the sea wall recently. With this new method, expenses of building the sea wall can be cut down and environment pollution around the sea wall can be reduced. An analytical solution for soilbag with semi-pervious boundary is proposed in this study. The cross-section of the soilbag in this theory is considered as a rectangle. By setting coefficients for consolidation solution of two square areas and summing the two parts, final solution of the rectangular area is obtained. Further research is made to compare calculation results from this study and other three methods. After the comparison, it concludes that calculation results from this study are very close with that of finite-element method, and also, the soilbag method possesses a giant economic benefit and has a possibility to replace the jackstone method to construct a sea wall.

Abstract: The poisson ratio test equipment of large vibration compaction was designed and adopted to simulate the changes of poisson ratio in soil-stone mixture, by large laboratory vibration compaction test under the condition of different water content and different soil-stone proportion with sandy soil, silt soil and low liquid-limit clay. The volume expansion ration (γ_v) was introduced to study the influence mechanism of poisson ratio (μ) in mixture with different water content and different soil-stone proportion. The change regulation of poisson ratio with different dry density under the soil type be changed was revealed. The results show that if the water content and soil-stone proportion are fixed, poisson ratio increases with decreasing of dry density; poisson ratio in mixture decreases while the μ-γ_v curve is down and the trend growth of curve becomes slow with the increasing of stone content; poisson ratio in mixture increases while the μ-γ_v curve is up with the increasing of water content. The conclusion is valuable in poisson ratio study of soil-stone mixture.

Abstract: Based on the artificial neural network theory, a neural network approach is proposed for the analysis of slope displacement time series, the neural network system analysis of slope displacement time series is developed, it is proved that this method is scientific and reasonable.

Abstract: The finite element analysis is performed on the excess pore pressure dissipation for pressed pile installation using the ABAQUS finite element software. The modified Cam-Clay model is used to model the soil behavior. The finite slide contact model is used to model the pressed pile installation process. Based on the geology stratum of soils and drainage conditions, the excess pore pressure dissipation process is analyzed using the proposed method. The initial excess pore pressure distribution along the pile depth and the pile radius direction is obtained. The excess pore pressure dissipation after 98 days is analyzed.

Abstract: Laterite has high void ratio, low density, high moisture content, high plasticity, but it does not match with their physical nature, which has the relatively high strength and low compressibility. In order to improve the strength of laterite and increase its compactness, we usually use the method of dynamic compaction in some large engineering projects. Its easy to find that soil compaction degree increased with the moisture content When the content of moisture is low, but soil compaction decreased after reaching the highest. Multiple compaction can effectively improve the maximum dry density and reduce optimum moisture content, but after compaction number is too much that optimum moisture content dont increase obviously.

Abstract: Slope stability for soft clay is a hard problem in practice. In this paper, 2D and 3D finite element method (FEM) based on elastoplastic model are used to calculate the stress and displacement distribution in the soft clay slope under gravity and uniform load at the slope top. Stability analyses indicate that 3D boundary effect varies with the stress level of the slope. When the slope is stable, end effect of 3D space is not remarkable. When the stability decreases, end effect occurs; when the slope is at limiting state, end effect reaches maximum. The failure mode will not be the same if the slope is under different stress states; furthermore, a standard to evaluate slope failure with FEM calculation is established. The slope failure form caused by accumulative load is different from that caused by slope strength insufficiency. The energy causing slope failure spreads preferentially along Y-Z section. When the failure resistance capability reaches the limiting state, the energy can extend along X-axis direction. The 3D effect of the slope under uniform load on the top is related to the ratio of load influence width to slope height, and the effect is remarkable with the decrease of the ratio.

Abstract: With the development of the coastal cities, land reclamation has become an important part in the construction of coastal engineering and the coastal development projects. In this paper, we consider the dredger fill of Tianjin Textile Economic Region as the research subject, analyzing the engineering geological characteristics of the dredger fill in this area from its basic physical properties, the soluble salt of the study area, the variation laws of PH and cation exchange properties.

Abstract: Based on the test section on the expressway in Jiangsu, the thesis makes a model and then conducts numerical simulation on the settlement of soft soil subgrade by using FLAC^3D. The author set the filling layer null, and assigns a value to the loaded soil layer according to the construction sequence to realize multi-stage loading. The thesis also analyzes the pore water discharge and foundation deformation when the soil is consolidated. It shows that the simulation result is very close to actual measurement result, and can clearly demonstrate the real situation of settlement.