Advanced Materials Research Vols. 455-456

Abstract: This paper presents a pneumatic energy absorption system which can extend the energy-absorption beam automatically just before crash. The system consists of thin-shell energy absorption structure, pneumatic equipment and control system. When the control system detectives a crash accident is unavoidable, the pneumatic equipment will extend the energy absorption beam which is fixed in thin-shell energy absorption structure immediately to increase energy absorption space. This system has been equipped on a mass produced bus, and it indicates that the length of energy absorption space can be increased more than 230 mm instantaneously before a crash accident occurs. The time used to extend the energy absorption beam is less than 100ms.

Abstract: In high strength sheet metal forming process of body part, crack, wrinkle and severe thinning are the main faults usually. The degree of the faults varies with the change of input process parameters. Optimization for sheet metal forming process of body part is often considered as a multi-objective problem. Design of experiment method and genetic algorithm are often combined together to cope with this multi-objective optimization problem. High strength steel sheet metal forming process is relatively complex and difficult. An intelligent multi-objective optimization strategy for high strength sheet metal forming process was suggested based on genetic algorithm. Latin Hypercube Sampling method was introduced to design the rational experimental samples; the objective function was defined based on crack factor, wrinkle factor and severe thinning factor; the accurate response surface model for sheet metal forming problem was built; Multi-objective genetic algorithm was adopted in optimization and Pareto solution was selected. The strategy was applied to analyze a rocher. The result has proved this strategy suitable for optimization design of sheet metal forming process .

Abstract: Based on the microscope observation, the sedimentary characteristics of 20 groups sandstone samples were analyzed. All sandstones are taken from Shendong Coal Mine Area. The observation contents consist of rock constituents, grain size, textural and compositional maturity, cements and particle contact manner. Through the analysis of sedimentary characteristics and experimental determination, the research work reveals the influence factors of rock strength.

Abstract: As one geological disaster in the area of the Three Gorges Reservoir of China, perilous rocks dominate stability of slopes in the area. Most cliffs or steep slopes are alternately composed of inflexible rock such as sandstone and soft rock such as mudstone in the area, and due to different weathering velocities rock cells in soft rock below inflexible rock are usually developed. Any perilous rock belongs to a part of inflexible rock. To appraise the safety of perilous rock, it is essential to approach duration for perilous to form is of interest. In the present paper, authors analyze weathering velocity of rock cell and establish method to calculate length of critical rock cell. Duration for perilous rock to form can be divided into three parts, (1) duration to form critical rock cell, (2) damage duration of control fissure, and (3) fracture duration of control fissure. Further, methods to calculate these durations are established in details based on damage mechanics and fracture mechanics.

Abstract: Viscous property of saturated, wet, air-dried and oven-dried clay was evaluated by performing a series of one dimensional compression tests including primary loading, creep, global unloading and reloading tests. In the tests, axial strain rate was changed stepwise many times during monotonic primary loading at a constant strain rate. Test results show that viscous property of clay with different water content under different test condition is similar. In order to evaluate the viscous property of clay, parameter β was introduced basing on the present test results of clay and author’s previous study. β value of clay with different water content under different test condition varied from 0.034 to 0.064. Test results show that β value of saturated clay is generally larger than that of dried clay.

Abstract: The FEM positive analysis is made using H-K non-stationary creep constitutive model in this paper, the finite element program for non-stationary viscoelastic-plastic displacement back analysis is compiled combining the non-stationary viscoelastic-plastic program with the complex shape optimization method, and the displacement back analysis of soft tunnel engineering is conducted. The result indicates that the viscous aging characteristics of rock mass can be reflected objectively if rock mass is regarded as non-stationary viscoelastic-plastic model, and the plastic zone development of surrounding rock can be predicted considering the plastic flow of rock mass and regarding the back analysis results as the calculation parameters.

Abstract: In this paper, a practical technical approach for the evaluation of hydraulic conductivity in complex fractured rock mass is present in a seabed gold mine. According to hydrogeological conditions and characteristics survey in the field, geometry measuring method was applied in the in-situ investigation. Moreover, various methods were involved in the evaluation of the fracture development, water seepage features and permeability of the fractured rock mass. Through this study, a particular set of hydrogeological investigation, research and permeability evaluation methods were put forward, which are of great significance to the research and practical production of mines with similar cases.

Abstract: Dabashan Thrust and Fold Belt is situated in the transfer zone between Qinling Orogen and Sichuan Basin, where multi-generation calcite veins were developed. Two kinds of veins, bedding-parallel and fracture-filled veins, were collected for analyses of rare-earth elements (REE), samarium-neodymium and strontium isotopes. The total REE contents of the calcites from the bedding-parallel vein are much higher than those from fracture-filled veins and are rich in light REE (LREE). The chondrite-normalized patterns of REE curves of the calcites from fracture-filled veins are flatten. The 87Sr/86Sr and 143Nd/144Nd ratios of calcites from bedding-parallel vein are from 0.71068 to 0.71115 and from 0.51192 to 0.512058, respectively. On the 147Sm/143Nd vs 143Nd/144Nd diagram, the six samples from the bedding-parallel vein give a Sm-Nd isochron age of 357±230 Ma (2σ)( MSWD = 24) with an initial 143Nd/144Nd ratio of 0.51168±0.00019. However, the plots of the four samples from fracture-filled veins are rather scatter either on 147Sm/143Nd vs 143Nd/144Nd or on 87Sr/86Sr vs 143Nd/144Nd diagram. The fluids, from which the two kinds of veins precipitated, are different in origin and flowing.

Abstract: Perilous rock rupture is dominated by damage and fracture of the dominant fissure. Define factor of safety of perilous rock as the ratio of the damage fracture tenacity at the end area of the dominant fissure to the union fracture strength factor; Transfer loads acting on perilous rock to the dominant fissure, and divide them into four components, i.e., water pressure in fissure, average shear stress, moment around the end of the dominant fissure, and average tension stress, further, contribute methods to calculate fracture strength factor every components in view of fracture mechanics; Based on these individual fracture strength factors, establish the method to calculate the union fracture strength factor along fracture orientation near the end area of the dominant fissure. Further, on the basis of damage duration of the dominant fissure, provide the formula to solve the fracture tenacity of rock in damage area near the end of the dominant fissure in detal. Case analyses identify that it is reasonable to consider orientation earthquake force in stability analysis of perilous rock, which promulgates the stability status of perilous rock more effective than that by the limit equilibrium principle.

Abstract: Two methods of both the singular value decomposition (SVD) and the Bi-dimensional empirical mode decomposition (BEMD) were applied in extraction of gravity anomalies associated with gold mineralization in Tongshi gold field, respectively in this paper. Conclusions drawn by the comparison study are as follows: (a) The ore-controlling factor in the Tongshi gold field illustrated in the images obtained from the original gravity data by the two methods is the same that the Tongshi intrusions with a negative circular gravity anomaly and the ring contact metasomatic mineralization zone around the Tongshi intrusions with the positive gravity anomaly. (b) The two methods reveal the same spatial relationship between the ore-controlling factor and various gold mineralizations that the skarn and porphyry types of gold deposits are located within the complex pluton and the Carlin and Crypto-breccia types of gold deposits located within the contact metasomatic mineralization zone. (c) The image produced by BEMD not only reflects the structural features of the ore-controlling factor (Tongshi complex pluton), but also does the distributions of the other geological units in the Tongshi gold field such as the Mesozoic volcanic sedimentary basin in NW orientation with obvious negative gravity anomaly and the conceal metamorphic base swell in NW orientation with the positive gravity anomaly located between the Tongshi intrusions and the Mesozoic volcanic sedimentary basin. The image produced by SVD might depict in more detail the inner structure of the Tongshi intrusions and the ring contact metasomatic zone than that produced by BEMD. The higher gravity anomaly areas in island shape within the ring contact metasomatic zone may be caused by the skarn bodies with iron-copper-gold mineralization. (d) Under the constraints of the ore-forming geological setting, the results obtained from the original gravity data by combination of the two methods can depict the relationships between the ore-controlling factors and the gold mineralizations more exactly than the alternative methods.