Applied Mechanics and Materials Vols. 94-96

Abstract: Concrete filled tubular columns (CFT) have been used in buildings and bridges since long in history, and research reported in china is since 1970s. It has become popular as structural members due to their excellent structural performance characteristics, which include high strength, stiffness and high ductility. In modern building construction, steel rectangular hollow sections (RHS), square hollow sections (SHS) and circular hollow sections (CHS) are often filled with concrete to form a composite column. Such composite columns are well recognized in view of their high load carrying capacity, fast construction, small cross section, and high fire resistance. Compared to concrete-filled steel tubular (CFT) columns, the DSCFT can reduce its own weight while have a high flexural stiffness. Compared to traditional RC bridge columns and CFT columns it has high bending stiffness, avoids instability under external pressure, is light weight, possesses good damping characteristics due to increase in section modulus. In present study it is found that there is a definite increase in strength. Circular columns had all the properties better than other geometric shapes; strength increase was almost 20 % as compared to square columns. It is expected that if same ratios are maintained at projected scale, there would be a definite increase in strength and behavior of the columns. New concept of hollowness introduced is valid for all geometric shapes in DSCFTs and gives fairly good idea about its limits and effects on strength of columns. The equations given in different design codes give conservative values and hence need to be revised for DSCFTs both for seismic and normal designs.

Abstract: In the 21st century, because the shortage of mineral resources has seriously affected the development of China's industrial economy, investment and construction of mineral resource project is a very urgent task we must face. To achieve scientific investment decisions, we should be conducting multi-item comparison on the basis of the comprehensive evaluation of mining project and choose the best investment project so as to achieve rational development and utilization purpose and obtain the best economic benefits. In this paper, entropy-weight method is used based on the analysis compared with other evaluation and decision method, which should be a valuable reference.

Abstract: According to the research on land securitization of China and other countries, land securitization of contaminated site in U.S., and a financial bond called Brownfields Value Contract in U.S, the relationships between stakeholders of contaminated site and participants of bonds were analyzed. And the contaminated site bond’s investors and their market demands were discussed as well. Furthermore, the initial concept on issuing the contaminated site quasi-municipal bonds was proposed in order to provide the theoretical framework and a basis for financing on sites remediation and redevelopment.

Abstract: Based on the different failure mechanism for shallow and deep rock mass, combined with the test result of ground stress and difficulties of blasting rock in Xinwen mining area, used mines rock mass mechanics and modern blasting theory and actively carried out technical reform, the new forming control technology of directional fracture blasting and control technology of multi-directional fusion blasting and efficient blasting technology of compound cut had been adopted, which produced a set of new efficient blasting rock technology for large section rock roadway drivage in deep shaft with complicated conditions. The engineering practice application results showed that the new efficient blasting rock technology could decrease the numbers of shot holes and explosive material consumption, enhance drivage efficiency and circulation footage, ameliorate integral forming quality of roadway and realize maximum month drilling footage at 146 m, the research achievements can provide reference for deep roadway drivage construction in other mining areas with similar conditions.

Abstract: Based on the test data of shaking table tests of subway station structure in liquefiable ground under both near-field and far-field earthquakes, the spatial effects of dynamic pore water pressure (PWP)and peak ground acceleration (PGA)of liquefiable ground as well as peak strain response of the subway station structure are analyzed. The results show that there exists time-lag phenomenon of dynamic PWP ratio of each measuring point on different observation planes. The characteristic of input ground motion has a noticeable influence on the spatial effect of dynamic PWP ratio. The PWP ratio obtained on the major observation plane presents to be larger than that on the minor one when under far-field Songpan wave. Meanwhile, the peak acceleration of measuring points on both major and minor planes increase with the growing peak acceleration of earthquake. The law of PGA and frequency spectral character of measuring points on different observation planes or at different depth varies with each other, and there present remarkable spatial effect. The peak strain of central cylinders at the top and middle floors on the major plane appear larger than that on the minor planes. However, the peak strain of central cylinders at the bottom floor are more remarkable than that of the top and middle floors, There are sharp contrasts among the peak strain responses in different spatial positions of the station structure.

Abstract: In this paper, small strain model, being able to reflect the small strain characteristics of soil, was adopted to calculate and analyze surface deformation caused by shield tunnel construction. Under the single tunneling, the maximum surface settlement is generally just above the tunnel axis, and surface settlement is symmetric distribution on both sides of the tunnel axis, and decreases with the increase of the horizontal distance; the longitudinal surface settlement is "tilted S-shaped" curve, and tends to basically stabilize at a certain position behind the excavation face; The comprehensive comparison shows better consistency between the data from small strain model and those from actual measure, and then verifies the feasibility and effectiveness of the small strain model applied for surface deformation analysis caused by urban metro shield construction.

Abstract: Through comprehensively analyzing of the present earth excavation methods and combined with Kangwang road tunnel engineering earth excavation, proposing the layered basin earth excavation construction technology of excavation. We put the layered basin earth excavation construction technology of excavation in the practice of Kangwang road tunnel earth excavation, applying "MIDAS-GTS" software to simulate and cost accounting, from the technical and economic sides to validate this new layered basin earth excavation is advanced. And finally puts forward the conditions for the layered basin earth excavation, this new layered basin earth excavation construction technique can be popularized.

Abstract: Many hydroelectric power stations are constructed on rock foundations. Therefore, the stability of rock slope is critical for the engineering especially in the excavation state. The analysis for consequent rock slopes is not identical with the earth slope because of their material characteristics. In this paper, it is combined the elastic-plastic finite element method and safe factor strength reduction method for the solution of problem. Considering the multi-layer material of the rock slope, Drucker- Prager criterion is adopted for determining the yield station which has the modified format of Morh-Coulomb criterion overcome the corner point problem of application proper for rock material. The conditions both of displacement mutability and cut-through of plastic zone are described in detail and research deep for failure judged. Analysis and compare of the situations which contain displacement, plastic zone between pre-excavation and post-excavation by certain numerical example, some useful results are given for stability analysis of consequent rock slope.

Abstract: One of difficulties in super long tunnels’ construction is the construction ventilation to meet the requirement of normal construction environment and assure the workers’ health. Using traditional tunnelling ventilation is very difficult to meet the need of super long tunnel construction. As the energy assumption is high and it is very expensive. This paper investigated the simulation of tunnel construction ventilation with large power jet fans during the construction of Jinping Auxiliary Tunnels by using the computational fluid code FLUENT, the layout of jet fans in the tunnels is optimized. It is found that the best layout of the jet fan is aroud the transverse channel under the direction of airflow and jet fan should not be too far away from the transverse channel. The CO mainly distributes in the upper part of the tunnel when the jet fan is installed at a higher position, this layout of the jet fan is beneficial to construction of tunnels.

Abstract: Aerated concrete block has been used in infill wall of projects widely, but the cracking of aerated concrete block wall is a new common quality diseases appearing. This paper discusses the cause and treatments of common crack of aerated concrete block wall, which can provide a reference for the same kinds of engineering.