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Cui G.-Q.,Xian University of Architecture and Technology | Ma C.-G.,Northwest Research Institute of Engineering Investigations and Design | Xu Y.-L.,West Anhui University
Xi'an Jianzhu Keji Daxue Xuebao/Journal of Xi'an University of Architecture and Technology | Year: 2012

Large area rebound deformation due to excavation of loess foundation pit was modeled through conventional consolidation-rebound test in this paper, and deformation characteristics of soil in different depth were studied. The critical unloading ratio and ultimate unloading ratio were derived according to the unloading ratio-rebound ratio and unloading ratio-resilience modulus relationship, and the maximum depth of unloading influence area and strong rebound area could be estimated using these two ratios, which would provide theoretical basis for determining the rebound displacement of loess foundation pit. Finally, based on the former research, the maximum rebound depth, strong rebound area and total rebound displacement of a foundation pit in Xi'an was calculated, which were similar to the in-situ test results. This verified that the method given in this paper was feasible. Source

He Y.,Northwest University, China | Wang F.,CAS Institute of Soil and Water Conservation | Mu X.,Northwest University, China | Mu X.,CAS Institute of Soil and Water Conservation | And 3 more authors.
Advances in Meteorology | Year: 2015

The impacts of climate change and human activities on runoff and sediment load are too integrated to distinguish their own contributions. We develop a new method to assess the impact of human activities based on paired years with similar precipitation and evapotranspiration (ET0) conditions (SPEC) using a 55-year monthly data of climate, runoff, and sediment load in 1958-2012 at Zhangjiashan Hydrologic Station of Jing River, Loess Plateau, China. The SPEC of paired periods is defined by similar annual amounts (difference less than 2.0%) and similar process (linear correlations of monthly data less than 0.05) which could set a precondition fixing the possible influence of climate factors. The runoff declined in all nine paired years, but the sediment load and concentration decreased in seven (78%) and six (67%) paired years, respectively. The further analysis with available data of land use and land cover (LUC), Normalized Difference Vegetation Index (NDVI), and soil and water measures in this basin and the results could explain impacts of human activities well. The method could be used combining with the traditional methods in hydrological research. © 2015 Yi He et al. Source

Fang X.,Chengdu University of Technology | Li T.,Chengdu University of Technology | Ma H.,Northwest Research Institute of Engineering Investigations and Design | Wang F.,Chengdu University of Technology
Geotechnical Special Publication | Year: 2013

The attenuation plateau formed during radiation of dynamic compaction shockwave has a severe impact on construction work in loess backfill site and safety of buildings nearby. With essential targets of finding out reasons for attenuation plateau formation and providing basis for safe distance determination, geophysical prospecting was adopted in the test for in-depth investigation on the attenuation plateau characteristics of shockwave so as to provide basic data for attenuation law study of shockwave. Appropriate cut-off frequency was selected according to the test results and energy composition characteristics of elastic wave in semi-infinite soil. The shockwave energy was divided into body wave energy and surface wave energy in order to analyze energy attenuation characteristics of different waves. It is confirmed that the main reasons for attenuation plateau formation in the area were proportion and radiation characteristics of body wave energy. On this basis, staircase method was used to fit the radiation attenuation characteristics of dynamic compaction shockwave through subsection regression and compare with traditional fitting methods. The results showed that in close-distance and high-density dynamic compaction work, staircase method can be more accurate to mark out safe distance. © 2013 American Society of Civil Engineers. Source

Wang Y.,Xian University of Architecture and Technology | Yang Y.,Xian University of Architecture and Technology | Wei Y.,Northwest Research Institute of Engineering Investigations and Design | Liu J.,Xian University of Architecture and Technology | Li Y.,Xian University of Architecture and Technology
International Journal of Ventilation | Year: 2014

An air curtain generated by a jet is used to enhance an exhaust hood's capture ability in many research studies on local ventilation systems. This paper focuses on experimental methods to investigate the flow characteristics formed by an exhaust hood associated with a jet. The basic flow characteristics of this kind of exhaust hood are obtained by smoke visualization as a jet forms an air curtain, and the flow field is a combination of three parts: the jet flow region, the exhaust flow region and the vortex flow region. The conditions for forming an air curtain are determined. The air curtain generated by a jet can decrease the decay of the exhaust centreline velocity Vx, therefore enhancing the efficient capture distance. Increasing the exhaust flow rate has higher efficiency than increasing the supply air velocity to enhance the control effect. A regression formula to determine the required supply velocity is obtained if the capture distance and the capture velocity for different contaminants are known. Furthermore, it is found that installing vertical guardplates between the inlet and the outlet can effectively enhance the capture ability of the hood. Source

Yunjun L.,Northwest Research Institute of Engineering Investigations and Design | Qianli X.,Northwest Research Institute of Engineering Investigations and Design
Applied Mechanics and Materials | Year: 2013

Highway landslide disaster is the main type of geological hazard in China, which causes great economic loss and casualty. According to the engineering experience, discrimination and criterion of highway landslide disaster is put forward in this paper on the basis of laws and types of highway landslide disaster, which includes nine big macroscopic discriminant criterion and five big microscopic discriminant criterion. On the basis of development process and stage, the development of landslide disaster is divided into three stages according to the practical needs: early embryonic stage, medium potential stage, late induced phase. To regional discriminant criterion of highway landslide disaster as the foundation, this paper presents the discriminant criterion of development for highway landslide disaster. It is hoped that the findings herein will provide science direction for temporal discriminant of highway landslide disaster. © (2013) Trans Tech Publications, Switzerland. Source

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