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Jiahua Mao,Dajun Yuan,Binghui Wang,Shengnan Liu,Liping Chen 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1
In sandy soil, the timely and effective formation of a filter cake is crucial for maintaining the stability of the excavated face during slurry shield tunnelling. Obtaining real-time information on slurry infiltration and particle migration is challenging, which greatly impacts the formation of the filter cake. Real-time monitoring of slurry infiltration and particle deposition is achieved through the use of electrical resistivity and pore water pressure measurements of the soil. It has been discovered that the primary pathway for slurry infiltration is inevitable in sandy soil, and it is crucial to take note of the persistent slurry leakage resulting from this situation in the shield excavation face. The distribution of slurry particle deposition is highly non-uniform in the penetration direction, with the maximum particle deposition occurring at the slurry-soil interface. However, this deposition is susceptible to disturbance from shield cutting tools, which can compromise the safety of the excavation face. Even if the particle size of the slurry is smaller than the pore size of the sand stratum, the slurry with higher viscosity can still form an internal filter cake. Furthermore, the research indicates that slurry infiltration can induce regular changes in soil electrical resistivity.
Jiahua Zhang,Wei-jun Wang,Dao-bing Zhang,Biao Zhang,Fei Meng 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.11
Based on the existing research, the 3D active and passive failure mechanisms of a pressurized tunnel face are constructed. The nonlinear failure criterion is introduced into the limit analysis by virtue of the tangent technique. By neglecting the randomness of soil parameters, the collapse pressure of active failure and the blowout pressure of passive failure, namely the lower and upper limit of retaining pressure, are obtained along with the failure ranges. On account of the randomness of soil properties, a three-dimensional stochastic model of a pressurized tunnel face is established, and the optimal range of retaining pressure of the pressurized tunnel face is presented on the basis of the multiple correlated failure modes. Taking Changsha Metro Line 2 as an example, the good agreement of the measured data in situ with the reasonable range of retaining pressure verifies the presented method. The combination of limit analysis and reliability method can provide more scientific and reasonable support parameters for the construction of pressurized tunnels in the future.
Influence of Cutting Tools on Filter Cake Formation during Slurry Shield Tunnelling
Jiahua Mao,Dajun Yuan,Dalong Jin,Shengnan Liu 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.6
The filter cake on excavation face would be destructed periodically by cutting tools during slurry shield tunneling. The broken filter cake has a risk for face stability. The influence of cutting tools on filter cake was studied in this paper. A slurry-soil interaction model based on a multiphase flow theory which considers the solid particles and fluid in slurry was developed. The whole process of slurry penetration and filter cake formation on the excavation face of slurry shield can be described by this model. The motion state of cutting tools can be combined with this model and the effect of cutting tools on the slurry-soil interaction and pressure transfer mechanism was analyzed. Subsequently, the comparative calculations were presented to discuss the influence of tunneling parameters and the design of cutting wheel on filter cake formation during slurry shield tunnelling. The results indicate that the total area of filter cake on excavation face increases with the decreasing of revolutions per minute of cutting wheel and shield machine advance rate. The area ratio of filter cake on the center of excavation face always larger than other zone due to the lesser amount of cutting tools within one track in the center of cutting wheel. The results can provide a better understanding of how to set the shield tunneling parameters and design the layout of cutting tools for the stability of tunnel face.
A Routing Problem in Global Production Planning
Qian Huang,Jiahua Weng,Shunichi Ohmori,Kazuho Yoshimoto 대한산업공학회 2020 Industrial Engineeering & Management Systems Vol.19 No.2
The paper proposes an integrated approach for global production planning of production, transportation, and sales problems wherein transportation routing must be optimized simultaneously. Multi-market, multi-product, multi-plant, and multi-path frameworks comprise the research contexts. The objective of this study is to determine how to maximize total profit with path-selection of marine transportation. Products are transported from plants to markets by marine shippers that are business partners of the manufacturer. Unit production costs from each plant to each market are not constant in this study, changing according to transportation path, and discount policy on each liner. Since the proposed model is a nonlinear problem with a nonconvex objective function and has nonlinear constraints, the model was linearized into a mixed-integer linear problem so that it could be solved with an optimization solver. moreover, computational experiments were conducted. the findings show that, because of transportation routing influences production allocation and sales operations, the proposed integrated approach is proven to be effective at increasing total profit and can be used as a decision support tool to aid global manufacturers to contract with transportation booking companies.
Effect of Au film and absorption groups on minority carrier life of porous silicon
Yue Zhao,Linjun Wang,Jiahua Min,Weimin Shi 한국물리학회 2010 Current Applied Physics Vol.10 No.3
In this paper, the samples were prepared with or without metal assistance in different time. The effect of Au film and absorption groups on minority carrier life of porous silicon was studied by using l-PCD measurements,and the result was further proved by FTIR spectra and SEM images. The results were showed that the existed hydrogen-related groups on the surface of porous silicon would decrease the minority carrier life and the grid Au film also can decrease the minority carrier life. The minority carrier life may be controlled by the more effective factor, metal elements or absorption groups.
Erosion Wear Characteristics of Hydraulic Jet Pipe Servovalve
YIN Yaobao,FU Jiahua,YUAN Jiayang,So-Nam Yun,Yoshito Tanaka 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
The situation considered here is that the surface of the spool of jet pipe servo valve is a conical surface that with a certain taper caused by the machining error and the spool mounting with the valve sleeve eccentrically. The models of the contamination wear and the durability life of jet pipe servo valve are established by using the theory of abrasive wear, the maximum allowable leakage of jet pipe servo valve and the distribution of the pollution particles in the hydraulic system. At last the models are verified by an example and the influencing factors of the servo valve contamination wear are analyzed. Results show that mathematical models are well agreed with wear processes, and durability life meets the national standard. At the same time, the durability life of jet pipe servo valve is longest when the spool has no eccentricity and taper. While the surface of the spool of jet pipe servo valve has a certain taper caused by the machining error and the spool mounting with the valve sleeve eccentrically, the durability life of jet pipe servo valve is the shortest. The results are useful for the prediction and calculation of wear and durability life of jet pipe servo valve and have an important role on the anti-wear design of jet pipe servo valve.