Applied Mechanics and Materials Vols. 256-259

Abstract: By using the mine coal sample (DT - 3) and its CT image sequences, the application of stereology knowledge from the two dimensional perspective gets the DT - 3 CT images were a series of calculation for characterization of crack of second order tensor, and that the second order tensor of the characteristic value can be a very good explanation coal samples in a single shaft confining pressure under the action of the whole process of mechanical failure mechanism.

Abstract: Combined with the uplift static load test of large-diameter steel pipe pile in Xiangshan Port bridge of Ningbo, make analysis of Q-s curve and s-lgt curve, axial force distribution curve and unit shaft resistance, revealing the uplift characteristic of the steel pipe pile. The analyses show that the uplift steel pipe pile is pure friction pile, the uplift load is decreased downward through the axial force of pile body, the shaft resistance gradually plays from top to bottom and play completely in the upper soil. Moreover, it has used hyperbolic model to fit the measured Q-s curve by Matlab software, and the fitting precision is high. Then make the hyperbolic model non-dimensional, and attempt to predict ultimate bearing capacity using the maximum curvature point of the non-dimensional hyperbolic model, to get some mechanical characteristic.

Abstract: Four kinds of tri-axial shear structural yield stress is studied by controlling the pre-test consolidate degree and draining condition during the test. The results showed that draining condition influenced the tri-axial shear structural yield stress. When under the UU condition, structural characteristics appeared not clearly; when consolidated before testing and un-drained during test, only the undisturbed soil performed the structural yield stress; when draining during testing, the undisturbed soil showed the increased structural yield stress while the remolded soil could form certain structure. The impact of the draining condition on the structural characteristics is incurred by the change of the internal structure, which means that the draining condition have changed the arrangement and connection of the soil particles, then changed the soil structural properties.

Abstract: Frost heaving damage of water conservancy project is widespread. In order to research the failure problems of hydraulic soil slope in dark seasonal frozen soil region, laboratory model test is carried out combined with field test section practical situation, which is the prototype of this model test. It is researched that the rule of frost heave parameters variation and the damage of soil slope during freeze-thaw cycling. That offers theoretical basis and reference for construction of water conservancy project, which will mitigate the effect and damage of freeze-thaw on hydraulic soil slope stability.

Abstract: Convolution PML is known to have excellent wave absorbing capability, and has been used combined with FDM and FEM. Most of them are splitting type formulation for explicit FEM or FDM. Here implicit non-splitting type convolution PML procedures consistent with mixed formulation FEM as well as displacement based FEM are developed. The resulting coefficient matrices for convolution PML are symmetric if corresponding coefficient matrices of FEM are symmetric. The developed method is applied to dam-reservoir-foundation systems including reservoir cavitation, and the validity of the method is demonstrated.

Abstract: Collapsing and shrinkage of hole wall are two troubles to drilling of bored pile. In order to avoid such troubles, ultimate hole depth of bored pile was deduced with dry excavation technology. To hydraulic excavation technology, by the method of finite element numerical simulation and finite element strength reduction, excavation process of hole of bored pile are simulated in ADINA and ANSYS software, The influences of hole radius, hole depth, power of rotary drilling rig and pressure of auger boring tool on stability of hole wall are analyzed. The analysis indicate that the major problem of stability of hole wall of bored pile in seasonal frozen ground in the west of China is hole shrinkage. the deeper and bigger the hole are or the greater the pressure of auger boring tool is, the more serious the phenomenon of hole shrinkage is. Under other same conditions, to reduce pressure of auger boring tool less than to 35KPa, hole shrinkage can be reduced effectively.

Abstract: According to the theoretical formula of compacting displacement field due to jacked pile in semi-infinite soil, calculation of displacement field produced during construction process of precast pile was carried out. And the changing trends of radial displacement with depth of pile penetrating, the maximum radial displacement with normalized distance r/D and vertical surface displacement with normalized distance r/D were analyzed in this paper. Then the Comparison between theory calculation results and the field test data was presented. The results show that the theoretical formula will fit with the actual situation of the site, when the soft soil properties around the pile are homogeneous and saturated. The further solving of compacting displacement field due to pile jacking was put forward.

Abstract: Concerning the stress and displacement of the cap under lateral load with or without pile partner, reference on PCC lateral load test and numerical simulation, build finite element model of a pile under lateral load to study the stress and displacement of the cap, calculations show that the diffusion effect help partner to reduce stress concentration of the pile cap, and foundation slab can be designed thinner if there are pile partners.

Abstract: The No.10 coal seam in the first mining area of Yuandian Coal Mine lies in Taiyuan Group limestone aquifer with rich water, the underlying limestone water is an important danger for mine water-filling. To ensure the safety of mining, it is necessary to study and analyze the mining conditions. On this basis, with the design of targeted prevention and treatment of water, we achieve the purpose of safe mining.

Abstract: For the angle tower foundation of 750kV transmission line, the overturning effect caused by wire tension is a control factor of tower foundation design. The pile foundation on loess was taken as a research object in this study, where two typical regions along 750kV Lanzhou - Tianshui - Baoji transmission line were selected to carry out the site full-size horizontal static load test. Through the arrangement of displacement sensors and earth pressure cells around piles, the load-displacement curve of pile lateral soil under horizontal loads was obtained as well as the distribution law of soil stress at different locations of the pile. Based on the "m" method, the soil stress at different locations of the pile was calculated. The results showed that the calculated results were well consistent with experimental results. This research work can provide a theoretical basis and design guidance for tower foundation selection and design optimization of 750kV transmission line.