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Zhang Y.,Zhejiang University City College
Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences | Year: 2013

To prepare nanofibrous membranes of poly (vinyl alcohol)/chitosan (PVA/CS) loaded with varied salvianic acid A sodium (SAS) contents. Ultrafine fiber mats were prepared with PVA/CS as matrix and SAS as model drug. The structure and morphology of the nanofibrous membranes were characterized by FT-IR and SEM. Drug-loading amount and drug release profiles of these membranes were determined by UV VIS spectra, and the degradation of the membranes was also investigated. Average diameters of PVA/CS/SAS nanofibers with different SAS contents were 280 ≊390 nm. Drug-loading amount of these nanofibrous membranes was high and exhibited sustained and controlled release behavior for SAS. The PVA/CS/SAS nanofibrous membrane prepared in this study loads drug uniformly and has remarkably sustained release behavior, which may offer strategies for the research and development of novel topical drug delivery systems.

Wei G.,Zhejiang University City College
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The observed data of surface settlement caused by construction of Qingchun Road River-Crossing Tunnel in Hangzhou are collected, and a method to select surface settlement values during the construction stage is put forward. Based on the data of ground loss ratio induced by shield tunnel construction in Beijing, Shanghai, Nanjing, Guangzhou, Wuhan, Tianjin and Shenzhen, seventy-one groups of data are statistically analyzed. The results show that the ground loss ratio ranges from 0.2% to 3.01%. About 95.77% of the ground loss ratio is 0.20%~2.0%, and about 43.66% of the ground loss ratio is 0.5% ~1%. The ground loss ratio is 0.20%~2.0% for the cohesive soil area. The ground loss ratio is dependent on the construction level, soil properties and buried depth of the tunnel. With the increase of the tunnel buried depth, the ground loss ratio overall decreases, especially when the buried depth is more than 25 m. The relationship between the ground loss ratio and the tunnel buried depth can be approximately expressed by power functions.

Wu H.,Yiwu Industrial and Commercial College | Wei G.,Zhejiang University City College
Modern Tunnelling Technology | Year: 2014

This paper presents that the curve of soil settlement induced by small-interval double-bore parallel shield tunnel construction conforms with the normal distribution, and summarizes the calculation method for surface settlement. Aiming at the deficiencies of various calculation methods, the modified 2D Peck formula is established to calculate the deep soil settlement while considering the asymmetry of the settlement curve. Based on the research of calculation parameters, the measured results show that iTotal/iAdvancing tunnel (i: width coefficient of the settlement trough) decreases linearly with the increase of h/D, thus giving the formula for iTotal and ηTotal (η: Soil loss rate). Additionally, this paper firstly proposes the coefficient C of relative horizontal distance between two tunnel axes (C<0.6; C=L/(h+R)), to which the shape of the total ground settlement curve is related. According to the case study, the predicted values agree with the measured ones and the calculation is relatively simple.

Wei G.,Zhejiang University City College | Li G.,Zhejiang University | Su Q.,Zhejiang University
Modern Tunnelling Technology | Year: 2014

An underground passage passes over the existing shield-driven tunnel of the Hangzhou Metro line 1. Due to the complex geological conditions and surrounding environment of the over -passing section, tunnel deformation has to be strictly controlled. For this reason, control measures like foundation reinforcement and sectional excavation are considered in the tunnel design. Based on the monitoring data from the pile foundation construction and foundation pit excavation, this paper analyzes the rules and characteristics of the vertical displacement, horizontal displacement, and convergence of the shield -driven tunnel at different construction stages. The results show that the pile foundation construction may cause vertical settlement of the tunnel (maximum: 5mm), but has little influence on the horizontal convergence; additionally, foundation pit excavation may cause tunnel floating (maximum: 5mm) and horizontal radial convergence, but has little influence on the horizontal displacement.

Gang W.,Zhejiang University City College
Disaster Advances | Year: 2013

The method established in the present study includes the horizontal distance "L" between the axes of two tunnels and considers the effect of the first tunnel construction on the second tunnel. Meanwhile, it reflects the asymmetric feature of soilsettlement curve. The measured results showed that there was significantly decreased linear relationship between i second/ifirst and h/(DL). The calculation formulae of parameter isecond and ηsecond were proposed.

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