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Liyun Li,Xiuli Du,Jing Zhou 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.10
In China, with the rapid development of subway construction, the site deformation induced by subway construction is an interesting and hot issue in civil engineering. Focusing on the mechanism and characteristics of site deformation induced by parallel shield tunnel construction in typical soil-rock composite strata of Changchun region, and relying on the subway tunnel between Northeast Normal University Station and Gongnong Square Station, which belongs to the Changchun Metro Line 1, the tunnel construction process is simulated using FLAC3D software. In this paper, the numerical modeling and parameters for shield tunneling are described in detail, and the mechanism and characteristics of site deformation induced by shield tunneling are discussed systematically. Furthermore, the influence of construction parameters on site deformation, including construction sequence, tunnel spacing and earth chamber pressure, are studied. The results can provide reference for similar projects in the future.
( Liyun Li ),( Huangqin Liang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2
Dewatering of foundation pit is a common engineering measure to ensure the safety of foundation pit construction. The actual site stratum often contains multiple aquifers. In order to save cost, pipe wells crossing multiple aquifers are often used for foundation pit dewatering in practical engineering. The key to successful foundation pit dewatering is the reasonable value of hydrogeological parameters in design. Based on the foundation pit dewatering project of Jiajie Station of Taiyuan Metro Line 2, according to the pumping test data of non-penetrating wells with double confined aquifers, the hydrogeological parameters of the site aquifer are inverted by using the steady flow formula, the straight line graphic method of unstable flow and the numerical simulation method. The results show that the hydrogeological parameters of site aquifer obtained by different methods have good consistency, and the results can be used in the design of foundation pit dewatering of Taiyuan Metro Project. Finally, through sensitivity analysis of influencing factors of foundation pit dewatering project, the method of determining permeability coefficient is discussed.
Liyun Xiang,Jing Ya,Lixia Li,Zhifeng Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.2
TiO2 nanotube arrays (TiO2NTs) were prepared by anodic oxidation, then soaked in thiourea solution, and finally transformed into modified anatase TiO2 structure by heat treatment. Through the test results of SEM, TEM, XRD, XPS, UV-vis diffuse reflectance spectroscopy, photo-current and so on, finding that S replaces Ti4+ in the form of S6+, and part of the Ti4+ is reduced to Ti3+. Ladder type energy band structure, producing by the appearance of S6+ and Ti3+, makes the electron–hole more easily and increases the carrier transfer speed to a certain degree. The photo-current size has increased from 1.07 mA/cm2 to 2.13 mA/cm2. By simulating decolorization test of sample to methylthionine chloride under visible light, the degradation rate of the modified sample to methylene blue increases from 32% to 63%, and increased by 1.97 times.
Yuxin Li,Keqiang Su,Peikang Bai,Liyun Wu,Bin Liu,Hongwen Su,Wenbo Du 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.5
The Ti/TiBCN composite coatings were fabricated on the substrate of Ti6Al4V alloy by laser cladding. The effects of TiBCNcontent on the microstructre, microhardness, corrosion resistance and tribological properties of the composite coatings werestudied. The results showed that, when the TiBCN content was 60 wt%, the composite coatings were mainly composed ofthe dendritic and rod-shaped TiBCN phases, small white lump TiC phases, fine lamellar TiN phases, small and scatteredwhite block TiB2phases, In addition, there was a small quantity of short whisker Al3Tiphases and uniform layer blockTiAl phases. Furhtermore, the maximum microhardness was 1596 HV, which was about 4.6 folds greater than that of thesubstrate; the corrosion potential (Ecorr) reached − 1.258 V and the corrosion current density (Icorr) was 4.035 × 10−5 A/cm2,which was one order lower than that of the substrate (1.172 × 10−4 A/cm2); the worn surface was relatively smooth and themass loss (1.22 g) was only 9/50 of that of the substrate (6.71 g).
Tong, Yilin,Li, Dapeng,Huang, Jun,Zhang, Cong,Li, Kun,Ding, Liyun Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.11
A new fiber optical sensor was developed for the determination of 2,4-dichlorophenol (DCP). The sensor was based on DCP oxidation by oxygen with the catalysis of iron(III) tetrasulfophthalocyanine (Fe(III)PcTs). The optical oxygen sensing film with $Ru(bpy)_3Cl_2$ as the fluorescence indicator was used to determine the consumption of oxygen in solution. A lock-in amplifier was used for detecting the lifetime of the oxygen sensing film by measuring the phase delay change of the sensor head. The different variables affecting the sensor performance were evaluated and optimized. Under the optimal conditions (i.e. pH 6.0, $25^{\circ}C$, Fe(III)PcTs concentration of 0.62 mg/mL), the linear detection range and response time of the sensor are $1.0{\times}10^{-6}-9.0{\times}10^{-6}$ mol/L and 250 s, respectively. The sensor displays high selectivity, good repeatability and stability, and can be used as an effective tool in analyzing DCP concentration in practical samples.
Yayi Cheng,Jianfeng Huang,Liyun Cao,Yongfeng Wang,Ying Ma,Shaohua Xi,Bingyao Shi,Hui Xie,Jiayin Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.15 No.01
SnSe2 and SnSe nanocrystals were prepared using a simple solvothermal method by changing the molar ratio of SnCl2 · 2H2O and Se powder. When SnSe2 and SnSe are acted as lithium ion battery anodes, the SnSe hybrid structure shows more excellent electrochemical performance than that of SnSe2 interconnected nanosheet. It delivers a reversible capacity of 1023 mA h g -1 at a current density of 200 mA g -1, and maintaining a capacity of 498 mA h g -1 till 120 cycles. According to many present works, SnSe2 with interconnected thin nanosheet should possess more superior property than hybrid structured SnSe due to short charge transfer paths. However, in our research, the result is the opposite. Therefore, we consider that the superior electrochemical performance of SnSe is attributed to its highly reversible conversion reaction mechanism than SnSe2.
Hydrothermal Synthesis and Electrochemical Property of Self-Assembly K10 [H2W12O42] · 10H2O Nanorod
Xingang Kong,Wen Li,Liyun Cao,Jianfeng Huang,Jianpeng Wu,Jie Fei,Jiayin Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.6
Using KOH and WO3 as raw materials, K10[H2W12O42] · 10H2O nanorod was successfully synthesized via controlling the pH value and the K/W mole ratio of hydrothermal system. The structure and morphology of the samples were characterized by XRD, SEM, TEM, HRTEM and selected area electron diffraction (SAED). The size of K10[H2W12O42] · 10H2O nanorod was about 300 nm in width and 3–10 µm in length. The nanorod consisted of self-assembly nanowires with about 10 nm in width. Moreover, the electrochemical performance of K10[H2W12O42] · 10H2O as anode material was investigated, indicating that the as-prepared sample electrode possessed a certain ability of lithium ion insertion/extraction, and exhibited a high initial discharge capacity of 310 mAh g-1.
The Microstructure and Magnetic Properties of Melt-Spun CeFeB Ribbons with Varying Ce Content
Xuchao Wang,Minggang Zhu,Wei Li,Liyun Zheng,Dongliang Zhao,Xiao Du,An Du 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.1
The microstructural and magnetic properties of melt-spun ribbons with thecomposition (CexNd100-x)30FebalCo4Ga0.2B0.92 (where x = 50, 60, 70, 80, and 90)were investigated. The ribbons were examined with Scanning ElectronMicroscopy (SEM), Transmission Electron Microscopy (TEM), and VibratingSample Magnetometry (VSM). It was found that the grain size of the ribbons ison the nanometer scale, and the grain size decreases with decreasing Ce content. The magnetic hysteresis loops showed that the magnetic properties of theribbons gradually deteriorated with increasing Ce content. This is because themagnetic polarization (Js) and magnetocrystalline anisotropy field (HA) ofCe2Fe14B are smaller than those of Nd2Fe14B. Furthermore, from the initialmagnetization curve it was found that increasing the Ce content changes thecoercive force mechanism to the nucleation mechanism. When Ce contentaccounts for 90% of total rare earth metals, the coercive force mechanismmainly appears to be a nucleation mechanism.
Jinkun Sun,Rita Yi Man Li,Lindong Li,Chenxi Deng,Shuangshi Ma,Liyun Zeng Techno-Press 2023 Advances in concrete construction Vol.15 No.5
Fast infrastructure development boosts the demand for shotcrete. Despite sand and stone being the most common coarse and fine aggregates for shotcrete, excessive exploration of these materials challenges the ecological environment. This study utilized an industrial solid waste, high-titanium heavy slag, blended with steel fibers to form Wet Shotcrete of Steel Fiber-reinforced High-Titanium Heavy Slag (WSSFHTHS). It investigated its workability, shotcrete performance and mechanical properties under different water-to-cement ratios, fly ash content, superplasticizer dosage, and steel fiber content. The tunnel excavation and support were investigated by conducting finite element numerical simulation analysis and was used in 3 tunnel lining pipes in Zhonggouwan tailing pond. The major findings are as follows: (1) The water-to-cement ratio (w/c ratio) significantly impacted the compressive strength of WSSFHTHS. The highest 28-day compressive strength of 60 MPa was achieved when the w/c ratio was 0.38; (2) Adding fly ash improved the workability and shotcrete performance and strength development of WSSFHTHS. The best anti-permeability performance was achieved when the fly ash constituted 15%, with the lowest permeability coefficient of 4.596 × 10-11 cm/s; (3) The optimum superplasticizer dosage for WSSFHTHS is 0.8%. It provided the best workability and shotcrete performance. Excessive dosage resulted in water bleeding and poor aggregate encapsulation, while insufficient dosage decreased flowability and adversely affected shotcrete performance; (4) The dosage of steel fibers significantly impacted the flexural and tensile strength of WSSFHTHS. When the steel fiber dosage was 45 kg/m<sup>3</sup>, the 28-day flexural and tensile strengths were 8.95 MPa and 6.15 MPa, respectively; (5) By integrating existing shotcrete techniques, the optimal lining thickness was 80 mm for WSSFHTHS per simulation. The results revealed that after using WSSFHTHS, the displacement of the tunnel surrounding the rock significantly improved, with no cracks or hollows, similar to the simulation results.