Test Study on the Air Permeability of Remolded Q3 Malan Loess

Jia Liu,Xi’an Li,Zeze Guo,Quan Xue,Li Wang,Jinyang Liu 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.8

Gas permeability is an important parameter in the determination of the pore structure characteristics of loess, especially in engineering fields such as earthwork and landfill cover treatment. With an improved ZC-2015 air permeameter, the air permeability (ka) testing under different water contents (w), dry densities (ρd) and wetting paths was conducted on remolded Q3 Malan loess from the Chanhe River area in Xi’an, Shaanxi, China. The results indicate that the ka of the remolded loess decreased rapidly as ρd increased and exhibited a relatively complex pattern as w increased. When w was less than the plastic limit (wp) and ρdwas relatively low (1.35 g·cm−3, 1.45 g·cm−3), ka decreased as we increased. When ρd reached a certain value (1.50 g·cm−3, 1.65 g·cm−3), the ka–we curve exhibited a notable turning point. When ρd continued to increase 1.70 g·cm−3, ka decreased as we increased. The results of microscopic analysis, suggested that under the action of different water content and compaction, levels of aggregates and pore structures were formed. A Poulsen model was used to predict the ka and the test results were in relatively coincident with the calculation results, demonstrating that the Poulsen model is applicable.

A Coupling Method of Response Surfaces (CRSM) for Cutting Parameters Optimization in Machining Titanium Alloy under Minimum Quantity Lubrication (MQL) Condition

Zhiqiang Liu,Ming Chen,Jinyang Xu,Shu Han 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

This paper presents a new flexible method referring to coupling response surface methodology (CRSM) to acquire optimum cutting parameters in machining of difficult-to-cut titanium alloy under minimum quantity lubrication (MQL) condition. Cutting speed, feed rate and depth of cut are designed as three factors by using the Taguchi method, which are also subject to several constraints including processing efficiency, cutting force and surface quality. In addition, turning experiments of titanium alloy were performed in order to set up the model based on Taguchi experimental design and multiple regression method. ANOVA was carried out to prove the adequacy of the developed mathematical model and the influences of cutting parameters on constraints were also observed. The results indicated that the feed rate was the dominant factor affecting surface roughness and cutting forces, which were minimized when the feed rate and depth of cut were set to the lowest level, while cutting speed was set to the highest level. Moreover, the predicted values obtained by CRSM were in good agreement with the experimental values, which indicated that CRSM was an effective method to determine optimum cutting conditions for machining process under MQL condition.

Numerical Simulation of Temperature Effects on Mechanical Behavior of the Railway Tunnel in Tibet

Shouhua Liu,Jinyang Fu,Junsheng Yang,Han Feng 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.12

Under the influence of plate collision, the high geothermal is a widespread phenomenon within the region of Tibet. Due to the aforementioned high geothermal, lining cracking is a common disaster in Sangzhuling tunnel during construction period. This paper presented the mechanical behaviour of tunnel lining under high geothermal temperature, which is studied by thermo-mechanical numerical method. The results both from field investigation and numerical analysis demonstrate that high geothermal temperature can cause the tunnel lining cracking and the variation of the stress of the tunnel lining. Thus, a novelty sandwich composite lining supporting scheme is proposed to overcome such geothermal temperature effects, in which a thermal insulation layer between primary supporting and secondary supporting is designed. The numerical analysis results indicate that the insulation layer can significantly improve the mechanical characteristics of the lining structure. In addition, the effect of the insulation layer is not linear with its thickness. For this reason, the optimuminsulation thickness of the insulation layer is chosen as 0.06 m, which was optimized by a numerical parametric analysis. The research can provide a reliable reference for tunnelling works in high geothermal regions.

Study on Deterioration Characteristics and Fracturing Mechanism of Concrete Under Liquid Nitrogen Cold Shock

Jialiang Liu,Yu Jin,Yujie Zhu,Jinyang Li,Xuguang Zhang,Chao Tao 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.1

Insight into Fundamental Rules of Phenylenediamines Selective Monoacylation by the Comparisons of Kinetic Characteristics in Microreactor

Xu Qilin,Liu Ji Ming,Yao Hongmiao,Zhao Jinyang,Wang Zhikuo,Liu Junli,Zhou Jiadi,Yu Zhiqun,Su Weike 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.10

In this paper, the kinetics of acylation reaction of o-phenylenediamine/p-phenylenediamine and benzoic anhydride were determined in microreactors, respectively. A kinetic model was established, all kinetic parameters including reaction orders, reaction rate constants, pre-exponential factors, and activation energies were acquired. Validation experiments showed experimental data fit well with calculated data at different reactant concentrations and residence times. The comparisons of the reaction rate constants and activation energies were summarized to show the difference of chemical reactivities of phenylenediamines. According to the calculation of the kinetic model, the optimized reaction conditions were listed to meet the monoacylation selectivity equal to 97.0%.

Self-healing capacity of damaged rock salt with different initial damage

Chen, Jie,Kang, Yanfei,Liu, Wei,Fan, Jinyang,Jiang, Deyi,Chemenda, Alexandre Techno-Press 2018 Geomechanics & engineering Vol.15 No.1

In order to analyze the healing effectiveness of rock salt cracks affected by the applied stresses and time, we used the ultrasonic technology to monitor the ultrasonic pulse velocity (UPV) variations for different initial stress-damaged rock salts during self-healing experiments. The self-healing experiments were to create different conditions to improve the microcracks closure or recrystallized, which the self-healing effect of damaged salt specimens were analyzed during the recovery period about 30 days. We found that: The ultrasonic pulse velocity of the damaged rock salts increases rapidly during the first 9 days recovery, and the values gradually increase to reach constant values after 30 days. The damaged value and the healed value were identified based on the variation of the wave velocity. The damaged values of the specimens that are subject to higher initial damage stress are still keeping in large after 30 days recovery under the same recovery condition It is interesting that the damage and the healing were not in the linear relationship, and there also existed a damage threshold for salt cracks healing ability. When the damage degree is less than the threshold, the self-healing ratio of rock salt is increased with the increase in damage degree. However, while the damage degree exceeds the threshold, the self-healing ratio is decreased with the increase in damage.

Structural Mechanical Characteristics of a Large Bolted Beam Reaction System and Its Modified Calculation Method

Feng Huang,Ban Zhang,Xingchen Liu,Jinyang Xiang,Guoqing Wan,Miaodi Qu 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

The primary error sources of engineering design for bolted beam reaction system with large size are mainly from the deformation of structure, mechanical behavior of connection joints. In addition, the simplifi ed calculation method of bolted connection has not formed a unifi ed understanding. A vertical static load test was carried out in the laboratory, and the deformation laws of the reaction beam were analyzed to obtain the mechanical characteristics of the connection joints by controlling the defl ection of the reaction beam. The composite eff ect coeffi cient k l of the variable section panel structure was introduced to the theoretical solution of the defl ection of the variable cross-section beam. Simultaneously, the fi nite element method was employed to establish the detailed model of the beam reaction system. The mechanical behavior of the reaction beam and the bolted joint are extensively studied, and the simplifi ed method of bolted joint is improved. The bolted connection is simplifi ed as a semi-rigid joint, and then the theoretical formula is proposed to calculate the defl ection and deformation of the beam structure under bolted connection. The defl ection and deformation of the reaction beam by the test and theoretical formula are consistent. The results show that the theoretical formula can well calculate the defl ection and deformation of structure members under bolted connection.

Carbon-coated Mg–Al layered double oxide nanosheets with enhanced removal of hexavalent chromium

Xiaogang Zheng,Fuyan Kang,Xinhui Liu,Hao Peng,JinYang Zhang 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

Carbon-coated Mg–Al layered double oxide (MgAl@C LDO) nanosheets were synthesized for the removalof hexavalent chromium (Cr(VI)) ions. Carbon coating could enhance the sorption capacity of Mg5Al1 LDOfor the Cr(VI) removal. The sorption capacity of Mg5Al1@C LDO increased and then decreased with anincrease in carbon-coated content, of which the Mg5Al1@C-2 with a carbon thickness of around 5.0 nmexhibited the best sorption capacity. The sorption behaviors of Mg5Al1@C-2 was explained by Langmuirsorption model, pseudo-second-order model, Weber–Morris model, and Boyd kinetic model. Mg5Al1@C-2 for Cr(VI) removal was a spontaneous, endothermic, and chemisorption process.

Equilibrium, kinetic and mechanism studies on the biosorption of Cu2+ and Ni2+ by sulfur-modified bamboo powder

Tian Ai,Xiaojun Jiang,Hongmei Yu,Hong-Bo Xu,Dawei Pan,Qingyu Liu,Dongyu Chen,Jinyang Li 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.2

Two biosorbents were prepared using bamboo powder modified with mercaptoacetic acid and carbondisulfide, which exhibits strong adsorption properties for Cu2+ and Ni2+. The obtained materials were characterized byFTIR. Maximum adsorption for both metals was found to occur around pH 5.0-6.5. The kinetic data followed thepseudo-second-order model. The maximum adsorption capacities of Cu2+ and Ni2+ on mercaptoacetic acid modifiedbamboo powder determined from Langmuir isotherm were 103.97mg g−1 and 61.35mg g−1, respectively. While oncarbon disulfide modified bamboo powder were 128.21mg g−1 and 56.82mg g−1, respectively. The adsorption mechanismanalysis revealed that the most possible adsorption mode of Cu2+ was coordination, and Ni2+ was ion exchange. The obtained adsorbents could effectively remove Cu2+ and Ni2+ from industrial electroplating wastewater and could beused repeatedly for more than five cycles.