Linear regression analysis for factors influencing displacement of high-filled embankment slopes

Zhang, Guangcheng,Tan, Jiansong,Zhang, Lu,Xiang, Yong Techno-Press 2015 Geomechanics & engineering Vol.8 No.4

It is a common failure type that high-filled embankment slope sideslips. The deformation mechanism and factors influencing the sideslip of embankment slope is the key to reduce the probability of this kind of engineering disaster. Taking Liujiawan high-filled embankment slope as an example, the deformation and failure characteristics of embankment slope and sheet-pile wall are studied, and the factors influencing instability are analyzed, then the correlation of deformation rate of the anti-slide plies and each factor is calculated with multivariate linear regression analysis. The result shows that: (1) The length of anchoring segment is not long enough, and displacement direction of embankment and retaining structure are perpendicular to the trend of the highway; (2) The length of the cantilever segment is so large that the active earth pressures behind the piles are very large. Additionally, the surface drainage is not smooth, which leads to form a potential sliding zone between bottom of the backfill and the primary surface; (3) The thickness of the backfill and the length of the anti-slide pile cantilever segment have positive correlation with the deformation whereas the thickness of anti-slide pile through mudstone has a negative correlation with the deformation. On the other hand the surface water is a little disadvantage on the embankment stability.

Carbon dioxide reforming of methane over MgO promoted Ni/CNT catalyst

Dehua Zhang,Guangcheng Wei,Yiru Wang,Jing Wang,Ping Ning,Qiulin Zhang,Mingzhi Wang,Tengfei Zhang,Kaixian Long 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.10

Carbon dioxide reforming of methane to syngas was investigated over a series of MgO promoted Ni/CNT catalysts. MgO played a critical role in improving the catalytic performance of Ni/CNT. The results showed that the addition of MgO strengthened the interaction of Ni and interior surface of CNT. Highly dispersed nickel particles with small size (less than 4.5nm) were also observed in MgO modified CNT. Otherwise, the NiO nanoparticles were facilely reduced over the catalyst prepared with a narrow size of CNT, as shown in H2-TPR. The reaction tests demonstrated that the Ni-based catalyst with an addition of MgO and narrow size of CNT exhibited better catalytic activity. Furthermore, the lifetime of Ni-based catalyst was prolonged effectively after adding MgO, attributed to the stabilization and dispersion of Ni particles and the effective restraint on the gasification of CNT.

Effects of Freeze and Cyclic Load on Impact Resistance of Filling Layer Self-Compacting Concrete (FLSCC)

Ning Li,Guangcheng Long,Qiang Fu,Cong Ma,Kunlin Ma,Youjun Xie 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.7

Filling layer self-compacting concrete (FLSCC) is a key material in newly-built China Rail Track System (CRTS), which is commonly subjected to cyclic dynamic load from high-speed train and various ambient temperature during service. In this paper, a series of indoor simulating experiments was conducted to investigate the impact resistance of FLSCC suffering from cyclic flexural load and different temperature conditions with a Φ75 mm split Hopkinson pressure bar (SHPB). The dynamic increase factors were introduced to evaluate the strain rate effect on various mechanical properties of FLSCC and the corresponding mechanisms were explained. Results show that the dynamic increase factor of compressive strength (DIFc) and peak strain (DIFε) of FLSCC increase linearly with logarithm of strain rate, while specific energy absorption increases exponentially with strain rate. The impact resistance of FLSCC is greatly influenced by cyclic flexural load and low temperature. The strain rate sensitivity of compressive strength of FLSCC at minus temperature (-20°C) is weaker than that at normal temperature (20°C) and after freeze-cyclic load coupling action the sensitivity decreases further. Similar tendencies were also observed in peak strain and specific energy absorption.

Analysis of underwater explosion shock on ship shaft stern bearing lubrication characteristics under different bearing working conditions

Zhu Junchao,Wei Guangcheng,Peng Zilong,Xia Zhaowang,Zheng Liangyan,Zhu Hanhua 대한조선학회 2022 International Journal of Naval Architecture and Oc Vol.14 No.1

Warship always face the threat of underwater explosion shock, which may affect the ship stern tube bearing lubrication performance when the propeller shaft is bending. This paper builds the coupling model of shaft longitudinal vibration and bearing lubrication with consideration of shaft axial shock and misalignment. The performance of stern bearing under the influence of explosion shock was analyzed by solving the generalized Reynolds equation, shaft longitudinal vibration equation and explosion shock equation. The result shows that: the effect of underwater explosion shock on bearing lubrication performance is transient, and the effect will be more obvious when the bearing works at close quarter, larger misaligned angle, eccentricity and rotation speed. Moreover, the edge effect which caused by shaft bending will increase with the decrease of explosion distance and the increase of eccentricity.

Passive velocity tomography for mudstone under uniaxial compression using acoustic emission

Anye Cao,Changbin Wang,Guangcheng Jing,Wu Cai,Guangan Zhu,Jing Li 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.1

A passive velocity tomography method using acoustic emission (AE) was used to study characteristics of AE responses and velocity redistributions in mudstone during uniaxial deformation. Two standard cylindrical samples were uniaxially deformed until failure with axial loading rates of 1.00 × 10–3 mm/s and 2.50 × 10–3 mm/s, respectively. AE activities were monitored using eight sensors and every 100 consecutive AE events were used for tomography calculations. For each sample, three typical tomography results were obtained which reflected significant variation of velocity redistributions. From the experimental data, it can be concluded that the stress drop point observed in the stress-strain curves with high energies and AE events indicated coalescence of micro-cracks and formation of the main shear plane. In the initial tomography phase, the velocity difference was low and few AE events were detected. As loading increased, AE events clustered and velocity differences became obvious with high velocities being mainly located near the sample boundary, whereas low velocities begun to propagate from the bottom corner to the core. When approaching failure, velocity anomaly regions further expanded and low velocity regions interconnected with the position being consistent with macro-fractures in the post-failure samples. The positions of the AE events with large energies over 50 μV·s were found to correlate well with high velocity regions in the tomography results whose calculation phase was conducted prior to the occurrence of large energy AE events. This method can be used for the prediction of large energy AE events in rocks under unconfined pressures.

Mechanism of rock burst induced by fault slip in an island coal panel and hazard assessment using seismic tomography: a case study from Xuzhuang colliery, Xuzhou, China

Changbin Wang,Anye Cao,Guangan Zhu,Guangcheng Jing,Jing Li,Tian Chen 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.3

Rock burst hazards induced by fault slip frequently occur in underground mining and threaten the safety of miners. In this paper, the structures of overlying strata, mechanism of fault slip, and rock burst pre-warning using seismic tomography were investigated in LW7192, a specific island longwall panel in Xuzhuang Colliery. The results show that an asymmetrical “T” structure of overlying strata is formed during LW7192 retreat, and the long hanging length of overlying key strata is maintained due to the short panel width. By analysing a modified fault sliding model, it is found that the time interval between two fault slips has a positive correlation with the energy released therein. The rock burst that occurred in LW7192 has the longest time interval between events compared with other high-energy tremors near the fault, and enormous elastic energies released by fault slip as a form of dynamic load. The superposition of dynamic loads and high stress concentration of the coal-rock mass contributes to the rock burst in LW7192. For forecasting rock burst hazards, seismic tomography was used and the results show that the velocity anomaly regions correspond well with the area of both strong tremors and the rock burst. Ultimately, large-diameter boreholes, directional hydraulic fracturing boreholes, and floor distressing boreholes were taken in the rock burst area, and the pressure relief is proved effective by seismic tomography assessment.

A quantitative evaluation method of coal burst hazard based on zone division and an analytic hierarchy process: a case study on Yanbei coal mine, Gansu Province, China

Fan Chen,Anye Cao,Linming Dou,Guangcheng Jing 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.5

The occurrence of coal bursts affects the safety of coal mines while coal burst hazard evaluation exerts a guiding influence preventing future coal bursts. Therefore, a method for quantitatively evaluating coal burst hazard was proposed based on zone division and an analytic hierarchy process (AHP). On this basis, by considering the distribution of influence factors of coal bursts in coal mining face (CMF) and means of influencing weight changes, the research aimed to enhance the accuracy and pertinence of coal burst hazard evaluation. By investigating the LW250204 of Yanbei Coal Mine in Gansu Province, China, it can be speculated that the CMF was influenced by various factors (including extra-thick coal seam, syncline and anticline tectonics, mining-induced disturbance, dip angle of coal seams, and mining depth) and thus suffered significant threat of coal burst. The results revealed the following three points: firstly, the degree of coal burst hazard had a positive correlation with the thickness of the coal seams, the mining depth, and mining-induced disturbance, while it exhibited a negative correlation with syncline and anticline tectonics. Moreover, it showed a parabolic correlation with the dip angle of the coal seams. Secondly, the zone division of the CMF was carried out according to the range of influence and changes in various factors. Based on AHP and the degree of influence of different factors on coal burst hazard, an evaluation matrix for the weights of influence factors driving coal bursts was established to quantify the differences between weights of various influence factors. Thirdly, based on the evaluation matrix for weights of influence factors, the relative coal burst hazard index was constructed to quantify the coal burst hazard in a given zone. Through testing, the goodness of fit between the distribution of the global relative coal burst hazard indices of the LW250204 and mininginduced tremors (MITs), as located, reached 90.8%, which validated the accuracy of the evaluation results. The research can provide a reference for quantitative evaluation of coal burst hazard in coal mines.

Swelling/Deswelling Self-Oscillating of Microgels Induced by the BZ Reaction with Fe(phen)3 Catalyst

Jie Ren,Jinfen Gu,Li Tao,Guangcheng Zhang,Wu Yang 한국고분자학회 2016 Macromolecular Research Vol.24 No.6

A novel kind of microgels, poly(NIPAAm-co-Fe(phen)3-co-AAc), were prepared by copolymerization N-isopropylacrylamide (NIPAAm), acrylic acid (AAc) and iron(II) 5-acrylamide-1,10-phenanthroline-bi(1,10-phenanthroline) (Fe(phen)3), the catalyst for the Belousov-Zhabotinsky (BZ) reaction. The microgels were characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS) and scanning electron microscope (SEM). In addition, the self-oscillating behaviors of the microgels were investigated in BZ system free of catalyst. Both the redox potential and transmittance self-oscillation were observed. Moreover, the amplitudes of poly(NIPAAm-co-Fe(phen)3-co-AAc) microgels are much larger than those of linear polymer and gel. This advantage originated from the special structure, size and composition of the microgels.

Mechanical Property Test and Analytical Method for Reactive Powder Concrete Columns under Eccentric Compression

Cheng-hua Shi,Min Long,Cheng-yong Cao,Guangcheng Long,Ming-feng Lei 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.4

Reactive Powder Concrete (RPC) has ultra-high strength, toughness and durability. Review studies were focused on the mechanical properties of RPC material and RPC beam. In this paper, the bearing features of RPC columns under eccentric compression with different section dimensions, reinforcement ratios, and conditions of with and without steel fibres were determined through large eccentric compression test of 22 RPC columns. The distribution patterns of stresses over the section of the RPC columns under large eccentric compression were determined under cracking loads. A simple analytical method for the cracking loads was also established. Test results revealed that the thickness ratio of elastic tensile region and the whole tensile region can be 0.4 (with steel fibres) or 0.5 (without steel fibres) when calculating the cracking loads. The tensile stress on the RPC columns showed an isosceles triangle distribution in the tensile region. A simple analytical method for calculating the ultimate loads of RPC columns under large eccentric compression was set up. Test results revealed that the equivalence coefficient of the RPC column in tensile regions can be 0.6 (with steel fibres) or 0.4 (without steel fibres). The method deduced in this paper can be used to design the RPC column under large eccentric compression.

Photocatalytic Degradation of Rhodamine B via Fe-g-C3N4 Activated Sulfate Radical-Based Advanced Oxidation Processes and the Synergistic Mechanism

Zhan Xinyuan,She Zhixiang,Yue Zhengbo,Hu Fupeng,Wang Guangcheng,Wang Shaoping,Li Wei,Liu Bing,Wang Jin 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.1

Fe-doped g-C 3 N 4 has been proven to have the potential of visible light photocatalysis, but its catalytic activity of peroxymonosulfate (PMS) is neglected. Herein, the complex advanced oxidation processes of Fe-g-C 3 N 4 mediated PMS and visible light photocatalysis was developed, named as Vis/Fe-g-C 3 N 4 /PMS system, whose eff ects and synergistic mechanism for decomposing Rhodamine B (RhB) was evaluated. The coupling of sulfate radicals and photocatalysis for RhB degradation showed that the synergistic effi ciency ( η Syn ) and factor ( S c ) were 20.1% and 4.82, respectively, with a degradation effi ciency of 99.8%. Iron species dispersed on g-C 3 N 4 provided active sites for PMS activation to generate sulfate radicals, simultaneously reduced the forbidden band, and separated the photo-generated charges of g-C 3 N 4 . h + , SO 4 · ‾ and 1 O 2 were the main active species, and the increase of 1 O 2 was the cause of the synergistic eff ect. The possible degradation path of RhB by this coupling system was proposed. Our fi ndings prove that Vis/Fe-g-C 3 N 4 /PMS system has a great potential to decompose dye wastewater, and also to be an environmental remediation perspective.