Applied Mechanics and Materials Vols. 170-173

Abstract: For the Three Gorges granite, a finite difference software package FLAC was used to study failure process of heterogeneous rock material. Based on mineral components identification results of the granite and fuzzy clustering method, the actual image date was transformed into the finite difference grid by applying image processing techniques. A convenient and efficient two-dimensional numerical modeling method for heterogeneous geomaterials was presented. Then, failure process of the granite were simulated in uniaxial compression test based on experimental strain soft model, and the stress concentration phenomenon was analyzed. The results show that the numerical modeling method based on digital image processing can be used to calculate the mechanical responses of geomaterials by taking their heterogeneities into considerations.

Abstract: sandy foundation easily liquefies under seismic load, which leads to damage to buildings and even collapse. Liquefiable sandy foundation is analysed and researched in the paper. Through the processing of sandy foundation we will see, CFG pile and Gravel pile together will improve the bearing capacity of liquefied foundation with obvious effect of liquefaction resistance. So the processing method is right and feasible.

Abstract: The disasters dynamics and security of phosphate are important problems in Phosphorus ore-deposit mining. So monitoring in unstable, hazardous areas and goaf can effectively focus on the activities of ground pressure. Based on mine-site exploration, engineering test, collection of physical and mechanical parameters for ore, research of geology and mining conditions, the main controlling factors of ground pressure were identified. Combining practical projects, the fuzzy matter-element model of stability evaluation on ground pressure in empty areas was built and analyzed, which showed the good agreement with the evaluation results and measured values. At the same time, based on the stability of underground mining partition, automatic monitoring system of phosphate was constructed, which may provide some useful advices for the safety study of ground pressure in phosphate rock mass.

Abstract: In order to consider the influence of water pressure on cohesive soil slope with groundwater, the local and global water pressure methods are proposed. The equivalence and applicability of the two methods based on the simplified Bishop’s method are analyzed. The local water pressure method considers the water pressures on boundaries as components and the global water pressure method considers the water pressures as a resultant force. The physical analysis and numerical verification showed these two methods are completely equivalent. While the global water pressure method is more convenient in hydrostatic condition, the local water pressure method is prior in seepage condition. It is also pointed out that there are significant defects in some regular expressions of simplified Bishop’s method. Because they neglect the moment generated by water pressure on the top boundary of slope or wrongly evaluate of the hydrodynamic failure states with hydrostatic stress parameters.

Abstract: Carbon Mudstone will have a complicated change in the aspect of physics, chemistry and mechanics behavior when wet. Thus, it is difficult to describe the process in a quantitative standard. In order to find out the effect of testing conditions and water content, there are two different conditions in test drying and original state samples, one is outdoor test and the other is indoor soaking test. What’s more, Fractal Theory is used in the research of Carbon Mudstone. The result shows: A short-lived process of water absorption and weight increment appears in the initial disintegration; Different conditions will result in different destructional forms of samples; The key reason of disintegration is that wetting and drying cycle results in the change of water content; The difference of water content partly affects the process before disintegration, but less affects fractal dimension after disintegration.

Abstract: For the time being the theory about the failure mechanism of the soft rocks, mechanical behavior of bolting-grouting support body in soft rocks has not been fully comprehended. The design of the bolting-grouting support is mostly based on experience and by analogy, and the theoretical analysis results are far more different with the practical engineering. To solve the problem, the researches on the bolting-grouting support mechanism of the soft rocks and the interrelationship between characteristic parameters of the surrounding rocks and structural parameters of bolting-grouting support body are carried out based on the nested models of original surrounding rocks and the bolting-grouting structure. The qualitative and quantitative relationship between characteristic parameters of the surrounding rocks and structural parameters of bolting-grouting support is found out. At the same time, it could also provide beneficial reference to the practical engineering design and construction.

Abstract: Abstract. The data of compaction test is processed by use of numerical method and least-squares fitting method respectively through MATLAB software. After a simple comparative analysis of the two results, this paper aims to reach the conclusion that when the distribution of test data points consistent with the characteristics of soil compaction, it is better and more accurate to use numerical method.

Abstract: On the basis of seismic wave recorded by Wolong Measuring Station in Wenchuan Earthquake occurred on May 12, 2008, and taking a high rock slope (about 1397m in height) at the bank of Zipingpu Reservoir as the specific example, analyses have been made, with Plaxis dynamical simulation analysis program, on characteristics of influence upon acceleration time history, shear strain distribution, principal stresses distribution and stability of high rock slope by original seismic wave, and seismic wave with frequency expanded by 1.5, 2 and 3 times, respectively. Results of the analyses demonstrate that dynamic response characteristics of the slope top are notably influenced by multiplication factor of seismic wave frequency. As far as the real slope in this article is concerned, it generally presents a gradual decrease of PGA of the top of high rock slope, reduction of slope body shear strain and a corresponding drop of dynamic response of slope body as a whole, with the increase of seismic wave frequency.

Abstract: The anchorage length of the bolt in rock bolt crane girder is obtained by means of rigid limit equilibrium method and the critical the anchorage length of bolt is calculated by analytical solution. Combined with the calculation results, the analysis on the mechanical characteristics is carried on by building the finite element model of rock bolt crane girder with different anchorage length of bolt. The analysis results indicate that the bearing characteristics of rock bolt crane girder are not improved significantly with the increase of anchorage length when the anchorage length of bolt exceeds the engineering critical anchorage length. The existence of critical anchorage length of blot is proved further, and the rationality of analytical solution for critical anchorage length is validated.

Abstract: Based on a deep foundation pit in Tianjin, the authors introduced the retaining structure type, surrounding conditions, and the geological conditions of proposed field. According to the engineering characteristics, the excavation was divided into three typical operating conditions. Based on the monitoring of staged excavation of deep foundation pit, analysis on horizontal displacement, deep soil displacement, column settlement and bracing axial force was carried out. The general rules of the deformation and internal force of retaining structures induced by staged excavation were given, which will provide the references for similar engineering.