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2001 Vol. 12, No. 4

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Geochemistry of Permian Coal and Its Combustion Residues in Huainan Coalfield, China
Wenhui Huang, Qi Yang, Suping Peng, Zhigen Zhao
2001, 12(4): 283-290.

INAA (instrumental neutron activation analysis) was used to determine the contents of trace elements in coal samples from 11 workable Permian coal seams in Huainan coalfield. With XRFS (X-ray fluorescence spectrometry), the geochemical composition of its combustion residues from Tianjiaan Power Plant and Luohe Power Plant was analyzed. In addition, the electron microprobe was employed to study the chemical composition of some fly ashes and bottom ashes. Compared with those of the coals around the world, most trace elements of the Huainan coal are characterized by a normal abundance. Like most coals worldwide, the elements Se, S, As, Sb, Br, U and Cl are enriched in Huainan coal according to dark's value, while the other elements tend to be diluted. The large fluctuation in the contents of trace elements in this kind of coal demonstrates great differences in coal seams. On the other hand, the contents of these elements are very similar in different bottom and fly ash samples. The elements with low organic affinity tend to concentrate in fly and bottom ash than in coal, especially those elements associated with Fe. However, the elements with strong organic affinity tend to be volatile during the combustion. Moreover, the abundance of the elements in fly ash and bottom ash changes with different densities and with different particle sizes. The bottom and fly ashes consist of glass, lime, mullite, coal residues and ferrite minerals. Some residual chars contain higher contents of volatile elements, such as S, P, Cl and As, indicating that the ash containing more residual chars has a strong adsorption of some hazardous elements, suggesting a possible utilization of power plant ash in the field of water cleaning.

An Analysis of Groundwater in Sinjar Plain (Northwest of Iraq) Using WQI Model
F Bassam, Al Bassam, M Ayad, Fadhil
2001, 12(4): 291-295.

Sinjar plain-northwest Iraq has an abundant amount of groundwater. Due to the importance of this water source, the water quality index (WQI) model was used in the classification of groundwater in the western and eastern regions of Sinjar plain for beneficial use. Groundwater samples were chemically analyzed to calculate the values of WQI. This model consists of a single number of the integrated deviation from standard quality, which indicates the relative importance of each relevant variable for beneficial use. The results indicate that the WQI could be used to determine the particular uses of groundwater. The groundwater in the Sinjar plain is more suitable for irrigation than for livestock drinking and domestic use.

Environmental Geochemistry of Mining Activities in Panzhihua Region, Southwestern China
Yangu Teng, Xiangu Tuo, Shiju Ni, Chengjian Zhang, Yuxia Ma
2001, 12(4): 296-300.

Mining activities have created huge uncovered slopes, large areas of gangue ground and extensive tailings dams. This paper presents the environmental geochemistry of mining activities in Panzhihua region. The selected elements (Ti, V, Mo. Ni. Pb. Cu) show similar distribution patterns of concentration anomaly in topsoil. These concentration anomalies are located in V-Ti-magnetite slope, gangues dam and coal mine. The distinction between anthropogenic contamination and natural background is made available by the use of the enrichment factor in this study area. The anomalies of EF were smaller than that of concentration. The results from EF show that the selected elements anthropogenic pollution (EF & gt; 1) in topsoil were located in both the coal mining area and the V-Ti-magnetite mining area. In addition, the pollution sources of selected elements came from V-Ti-magnetite, slag, gangues, coal and other pollutants from mining activities.

Research on Nonlinear Dynamic Characteristics of Structures Supported on Slide-Limited Friction Base Isolation System
Jian Fan, Jiaxiang Tang
2001, 12(4): 301-308.

This paper presents a new type of base isolation system, i. e., slide-limited friction (S-LF) base isolation system. Based on this system, the harmonic and subharmonic periodic response of S-LF subjected to harmonic motions is investigated by using Fourier-Galerkin-Newton (FGN) method with Flo-quet theory. The dynamic response of S-LF subjected to earthquake ground motions is calculated with a high order precision direct integration method, and the numerical results are presented in maximum acceleration response spectra of superstructure and maximum sliding displacement response spectrum form. The comparison of isolating effects of S-LF, pure-friction base isolation system (P-F) and resilient-friction base isolation system (R-FBI) shows that the isolating property of S-LF is superior to those of P-F and R-FBI. Finally by analyzing an engineering example, it is observed that the distribution of the maximum shear between floors and absolute acceleration of S-LF to earthquake ground motion is very different from that of traditional structures.

A Test Model of Water Pressures within a Fault in Rock Slope
Tong Yang, Baoxue Wang, Heng Hu
2001, 12(4): 309-311.

This paper introduces model test results of water pressure in a fault, which is located in a slope and 16 different conditions. The results show that the water pressures in fault can be expressed by a linear function, which is similar to the theoretical model suggested by Hoek. Factors affecting water pressures are water level in tension crack, dip angle of fault, the height of filling materials and thickness of fault zone in sequence.

Research on Practicability and Feasibility for a New-Type Tuned Mass Damper System-TMD
Yaoting Zhang, Ping'an Lei, Zaihua Liu, Ning Lin
2001, 12(4): 312-316.

Based on the principle of tuned mass damper (TMD). the method of using laminated rubber bearing (LRB) to connect TMD with structure is discussed in this paper. This is a new type of TMD system-suspended structure. To test the function of quake-reduction and the possibility of application, this paper explores the suspended top floor through shaking table test. In the model test, an electro-hydraulic shaking table was used. The main structure model was a four-story steel frame structure. The block to combat the structural quake was a concrete block. LRB was used to connect the block to the main structure. In order to analyze the efficiency of TMD, the fundamental frequencies of the main structure and block of TMD were measured separately first. Then. the frequencies of the main structure with the block and without the block were compared respectively under sine and imitative quake waves. The test shows that this new-typeTMD system is effective in combating the structural quake often reducing the acceleration of the top floor by more than 25 %. Because of the easy availability of the method, it is endowed with practical feasibility.

Fuzzy Decision of Ground Improvement Method
Zhongren Feng, Bing Han, Ruigeng Zhu
2001, 12(4): 317-320.

With the rapid development of expressway in China, the ground improvement is becoming more and more important. The decision of the ground improvement method often depends on the experience of an engineer. This paper sets up a module of multi-level fuzzy decision of the ground improvement method in the expressway construction which is mainly to set up multi-level structure module, to get value of the affected factors at rule level and index level, to set up the character index matrix of project level and to have a total evaluation on the projects. Combined with the project of ground improvement on the Second Cincture Road in Wuhan, a case study is carried out with satisfactory results.

Model Tests of Pile Defect Detection
Guocheng Li, Jingtao Wang
2001, 12(4): 321-324.

The pile, as an important foundation style, is being used in engineering practice. Defects of different types and damages of different degrees easily occur during the process of pile construction. So, dietecting defects of the pile is very important. As so far, there are some difficult problems in pile defect detection. Based on stress wave theory, some of these typical difficult problems were studied through model tests. The analyses of the test results are carried out and some significant results of the low-strain method are obtained, when a pile has a gradually-decreasing crosssection part, the amplitude of the reflective signal originating from the defect is dependent on the decreasing value of the rate of crosssection β. No apparent signal reflected from the necking appeares on the velocity response curve when the value of β is less than about 3. 5 %.

Applied Sequence Stratigraphy in Nonmarine Basin of China
Kuisheng Wei, Daliang Li, Shoupeng Zhang, Yunqing Hao, Zhenchuan Du, Guohong Zong, Yigang Qiu, Jianbao Wang, Herong Zheng, Yuanlin Pan
2001, 12(4): 325-336.

This paper presents a preliminary summary of the applied sequence stratigraphy in nonmarine basins in China. The geological and geophysical data show that the nonmarine sequences mainly resulted from both allocyclic and autocyclic processes where the most important factors were isolated tectonics and climate. However, the environmental factor should have been crucial. The depositional base level served as the sea level in the marine environment, while the water table, lake level and fluvial equilibrium were profiled in a terrigenous environment. This accommodation varied periodically with the base level, resulting in the formation of a series of depositional sequences in terms of genesis and space. Basically, the base level of the inner continent was not affected by the changes in the relative sea level. But there would have been some relations between the changes in the relative sea level and that in the continental base level during eustacy flooding. However, a small time lag existed between the changes in the marine basin and the inner continent basin, The lake basin is smaller than the marine basin, but its velocity of sediment supply is greater than that of the marine basin. Therefore, the number of nonmarine sequences is greater than that of marine ones in the same period. It is important to recognize the system tracts for the study of high-precision or high-resolution sequence stratigraphy, especially to analyze the low-stand systems tract with its depositional system. The sequence boundary is genetically characterized by subaerial exposure, stratigraphic truncation and subaqueous erosion. The deposition analysis of Zhanhua depression reveals 5 sequence architectures: alluvial-fluvial/lacustrine architecture, transitional architecture formed between haline (mesohaline) lake and fresh lake, marine duration-deep lacustrine architecture, half deep lacustrine-ramp architecture and fluvial-alluvial plain architecture. During the major development of the nonmarine basin, the step-faulting breaks controlled the depositional system. Usually, the low-stand complex fan, prograding wedge and high-stand turbidity fan were close to the third stepping break. In the low-stand period, the sediments went around the incised valleys which then were filled with sand bar near the second stepping break. At the first stepping break the sediments were bypassed step by step or the alluvial fan was deposited with forced regressions in the low-stand time. The low-stand wedge may serve as favorable subtle or complex traps at the basin floor fan. The economic effectiveness is measured with the borehole in Bohai Bay basin.

An Improved Method for Calculating Paleoheat Flow from Vitrinite Reflectance Profiles
Zhonghua Tang, Yonghong Wu, Sheng He, P F Siew
2001, 12(4): 337-342.

Based on the models developed by Lerche et al. (1984) and Pang et al. (1993), an improved model for calculating paleoheat flow into basins is investigated. The new model is an optimization problem with the state variables governed by a thermal conduction equation. A genetic algorithm is used to solve the highly nonlinear optimization problem. As an application, the model is applied to the research into the history of heat flow in the Pearl River Mouth basin located in the South China Sea. The numerical analysis shows that the simulation results are in good agreement with the measured data and indicates that the basin may have undergone three rifting and thermal events. It is also demonstrated that a high R0 gradient reflects a response to high paleoheat flow during the early, rapid subsidence stage, while a low R0 gradient is a result of the thermal decay during the thermal subsidence because of thermal contraction of a cooling lithosphere.

Evaluation of Petroleum System in Xihu Depression, East China Sea Shelf Basin
Jiaren Ye, Delin Lü, Huirong Gu
2001, 12(4): 343-350.

According to the theory of petroleum system and the characteristics of petroleum geology, the Xihu depression in the East China Sea shelf basin is divided into four petroleum systems: the Pinghu Formation as source rock and the Huagang Formation as reservoir rock, the Huagang Formation as source rock and reservoir rock, the Paleocene as source rock and the burial-hill as reservoir rock, and the Miocene as source rock and reservoir rock. The system with the Pinghu Formation as source rock and the Huagang Formation as reservoir rock is the most important one in the depression, which has high hydrocarbon generation and accumulation efficiency and is the most important object to hydrocarbon exploration at present.

Terrain Simplification Research in Augmented Scene Modeling
Delie Ming, Kefei You, Jinwen Tian, Jian Liu, Guangjun Wang
2001, 12(4): 351-355.

Augmented reality is the merging of synthetic sensory information into a user's perception of a real environment. As one of the most important tasks in augmented scene modeling, terrain simplification research has gained more and more attention. In this paper, we mainly focus on point selection problem in terrain simplification using triangulated irregular network. Based on the analysis and comparison of traditional importance measures for each input point, we put forward a new importance measure based on local entropy. The results demonstrate that the local entropy criterion has a better performance than any traditional methods. In addition, it can effectively conquer the 'short-sight' problem associated with the traditional methods.