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Jiang K.,Kunming University of Science and Technology | Cao J.,Kunming University of Science and Technology | Ma Y.,Broadvision Engineering Consultants
Applied Mechanics and Materials | Year: 2013

Based on the background of a foundation pit slope of the tertiary strong weathered basalt(TSWB), a quantitative analysis of the slope stability is proposed by combination of the limit equilibrium and the numerical analysis. The analysis also considers the effects of the natural state and soaking state Then, as an example, an ultra-deep foundation pit slope (UFPS) is analyzed under the background of TSWB. The Janbu method is used in the limit equilibrium because it can meet all the equilibrium conditions, including the force and moment equilibrium equation. The Lagrangian difference method which based on shear strength reduction is adopted in numerical analysis. Some meaningful conclusions can be obtained through comparing analysis the calculation results of Janbu method with finite difference method. These conclusions can be given a reference to similar projects. © (2013) Trans Tech Publications, Switzerland.

Zhang Y.,Beijing Forestry University | Yang J.-Y.,Beijing Forestry University | Wu H.-L.,Beijing Forestry University | Wu H.-L.,Tianjin University of Technology | And 4 more authors.
Ecological Engineering | Year: 2014

Vegetation restoration in abandoned mines is very difficult and time consuming because of the harshness of the ecosystem, i.e., the extremely high and steep slopes. To accelerate the process of vegetation recovery in abandoned mines, understanding the rules of vegetation succession and the variation in soil characteristics during this process is very important. In the Zhoukoudian vegetation restoration experiment demonstration area (a 12. ha area located in Fangshan District, Beijing, China), engineering measures, such as biological greening bags, eco-stick slope protection, container seedling planting and vegetative-carpet greening technologies, were applied to accelerate the process of vegetation recovery. In this study, 149 human-restored and spontaneously recovering slopes under three substrates were sampled to investigate the dynamic changes in soil and vegetation in different stages of succession by means of space-for-time substitution. WinTWINS was used to classify the samples, which experienced different recovery periods, into 6 plant community types. According to the results, the species richness index, Simpson's predominance index, the Shannon-Wiener index and the soil fertility of the communities dominated by young trees (V, VI) were higher than those of the communities dominated by grasses (I, II) or shrubs (III, IV); thus, plant communities V and VI are considered optimal representations of severely damaged surface-mine ecosystems. Our results suggest that native species should be planted to accelerate the succession process by implementing the best engineering measures for different substrate types during the initial restoration. © 2014 Elsevier B.V.

Jiang M.-J.,Tongji University | Zheng M.,Broadvision Engineering Consultants | Wang C.,China Academy of Space Technology
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

The problem of failure of soil is generally studied by shear band. The lunar environment is quite different from the earth such as Anhydrous, low gravitational fields, and very low atmospheric pressure etc.; and the internal friction angle of lunar soil is quite large. In this paper, particle rolling resistance and Van der Waals forces between lunar soil particles are taken into consideration in the new lunar soil contact model. With this model several flexible boundary biaxial compression tests are simulated by distinct element method (DEM). The results show that the formation of shear band is characterized with both strain localization and the pure rotation ratio (APR) localization; and the lunar environment has a significant influence on failure modes of samples, such as inclination and thickness of the shear band. The influence of lunar surface environment on the mechanical properties of lunar soil should be taken into account in lunar exploration.

Yang J.-R.,Kunming University of Science and Technology | Li J.-Z.,Tongji University | Shen J.-X.,Broadvision Engineering Consultants
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2012

A theoretical research work in relation to the dynamic impact effects of concrete-filled steel tubular tied-arch bridge under travelling vehicles was described. The mathematical model assumed a finite element representation of the bridge together with beam, shell, and link elements. And the vehicle simulation employed a 3 dimensional linear vehicle model with 7 independent degrees of freedom. In this way, the dynamic interaction between the bridge and vehicle model was simulated. And the dynamic amplification factors were computed for displacement and internal force respectively. The impact effects of vehicle on different bridge members and the influencing factors were studied. Meanwhile the acceleration responses of some bridge components were analyzed in the frequency domain. The dynamic amplification factors of some structural elements may exceed those specified in the design codes. And road surface roughness seems to be one of the major influencing factors. Compared to the longer hangers, the shorter ones can be ore frequently suffer from mechanical or fatigue failures.

Yang J.,Kunming University of Science and Technology | Zheng Z.,Urban and Rural Planning and Design Institute of Yunnan | Yang X.,Kunming University of Science and Technology | Bai H.,Broadvision Engineering Consultants
Applied Mechanics and Materials | Year: 2012

A load test on a multigirder concrete bridge of 25m Span having a noncomposite deck slab is described. The bridge was designed to have eight simple supported spans, each consisting of a cross section with six RC T beam. Through analyzing the static and dynamic character of bridge structures, calculating efficiency ratio of load test, picking up the results of observation points, it was determined that the girders were acting non-compositely with the concrete deck and that significant restraint was being developed at the bearing supports. Results of analyses conducted using the numerical model were compared to the measured response and found to be quite similar. By comparing the various load ratings, and by considering the nature of the unintended composite action and support restraint, decisions regarding the determination of a safe bridge rating are discussed. © (2012) Trans Tech Publications, Switzerland.

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