Deformation Characteristics and Countermeasures of shallow and Large-span Tunnel Under-crossing the Existing Highway in Soft Soil: a Case Study

Cheng-yong Cao,Cheng-hua Shi,Ming-feng Lei,Li-min Peng,Ruxue Bai 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

Hongmian Road goes under Jihe highway by the way of tunnel in Shenzhen City, Guangdong Province, China. The tunnel hassome special characteristics such as shallow depth, large span, soft soil, busy traffic, and long distance under-crossing the operatinghighway, thus there is great difficulty and risk during its construction. A series of in-situ tests were conducted to reveal deformationcharacteristics during tunneling beneath the existing highway by the double-side-drift method (DSDM). The results show that initialconstruction method and measures can't meet the safety requirement of tunnel construction, and the level of risk is extremely high, sothe construction method need to be timely adjusted. By comprehensive analysis, the double-side-drift optimum method (DSDOM) isput forward, on the basis of which a series of optimum measures also have been put forward, such as reasonable constructionmethods, the suitable length of bench and excavation, soil reinforcement measures on tunnel face, optimizing construction process,closing primary support in time and speeding up the construction of secondary lining. Then the feasibility of this optimizedconstruction method and measures are verified by the numerical simulations. Finally, from feedbacks of monitoring results, theoptimum method and measures have been proved to be reasonable and feasible, and they can guarantee a successful pass beneath theoperating highway.

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.

Structure and bioactivity of triterpenoids from the stems of Schisandra sphenanthera

Cheng-Qin Liang,Rong-Hua Luo,Ju-Ming Yan,Yan Li,Xiao-Nian Li,Yi-Ming Shi,Shan-Zhai Shang,Zhong-Hua Gao,Liu-Meng Yang,Yong-Tang Zheng,Wei-Lie Xiao,Hong-Bin Zhang,Han Dong Sun 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.2

Two new triterpenoids, schisphendilactoneA and B (1 and 2), together with three known triterpenoids,were isolated from the stems of Schisandra sphenanthera. Their structures were elucidated by spectroscopic methods,and the absolute configuration of 1 was determined bysingle-crystal X-ray diffraction. Compound 2 showedmoderate inhibitory activity against SW480 cancer cellline, and compound 5 exhibited promising anti-HIV-1activity with EC50 value of 0.52 lg ml-1 and therapeuticindex value of 117.12.

SYNTHESIS AND PROPERTIES OF ONE-DIMENSIONAL ALUMINUM NITRIDE NANOSTRUCTURES

YONG-BING TANG,HONG-TAO CONG,HUI-MING CHENG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2007 NANO Vol.2 No.6

This article presents a brief review of the recent research progresses achieved in the field of one-dimensional (1D) aluminum nitride (AlN) nanostructures. It mainly covers three aspects: The first one is to introduce the synthetic strategies for several classic 1D AlN nanostructures (such as nanofibers, nanobelts, nanorods, nanowires, nanotips, etc.) including template-confined reaction, arc discharge, catalyst-assisted growth, and vapor transport and related growth methods. The second is to elaborate some special physical properties, such as field emission and photoluminescence, which associate with the uniqueness of 1D AlN nanostructures. It is revealed that aligned AlN 1D nanostructures have low turn-on and threshold voltages, high emission current and small current fluctuation, and that the photoluminescence of AlN nanobelts are different from those of conventional AlN material. The third is to briefly illustrate the potential application of these 1D AlN nanostructures in composite materials. It is found that AlN nanowire is a good reinforcement for improving the mechanical and thermal properties of metal matrix composites, which can be expected to be utilized as packaging material with high strength and low thermal expansion. Finally, we summarize the major challenges in this field. Among them, a thorough understanding of the growth mechanism of 1D AlN nanostructures is the most important issue, and more precisely controlled growth is required to obtain tailored AlN nanostructures according to device applications.

Optimization of the microemulsion formulation of curcuma oil and evaluation of its acaricidal efficacy against Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae)

Cheng Zuo-Hui,Fan Fang-Fang,Zhao Jin-Zhong,Li Rui,Li Sheng-Cai,Zhang En-Jia,Liu Yu-Kun,Wang Jue-Ying,Zhu Xiang-Run,Tian Yong-Ming 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.4

The microemulsion formulation (hereafter formulation) of curcuma oil and its acaricidal efficacy against Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae) were optimized in the laboratory to evaluate their spray effectiveness of oviposition inhibition and repellence. Ethovision XT6 was used to analyse the effects of the sublethal concentrations (LC 20 ) of curcuma oil and the formulation on the behaviors of T. cinnabarinus. The results showed that Tween-80 was the best surfactant, Isopropanol was the best co-surfactant and K m = 2:1 was the best condition for the formulation. The prepared microemulsions are stable under conditions of centrifugation and incubation for extended periods. The results showed that the effect of the spray bioassays of the formulation against T. cinnabarinus continuously increased during the experiment, but for curcuma oil almost no longer increase observed when the exposure time went beyond 24 h. Moreover, compared with curcuma oil (LC 50 = 0.716%), the spray bioassay of the formulation (LC 50 = 0.035%) was stronger against T. cinnabarinus. The repellency of the formulation to T. cinnabarinus was stronger with increasing exposure time, but that of curcuma oil declined after 12 h of exposure. The mobile distance of T. cinnabarinus treated with the formulation continuously declined during the experiment but that due to the curcuma oil almost no longer declined when the treatment time reached 12 h. The maximum mobile frequency of T. cinnabarinus treated by curcuma oil and the formulation was recorded at 6 h and 12 h, respectively. Thus, the formulation is a promising candidate as a botanical acaricide of green vegetables.

An Analysis of the Ground Deformation Caused by Shield Tunnel Construction Combining an Elastic Half-Space Model and Stochastic Medium Theory

Cheng-hua Shi,Cheng-yong Cao,Ming-feng Lei 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.5

The ground movement induced by the construction of shield tunnels affects the safety of nearby underground pipes and aboveground structures. Therefore, the reliable prediction of ground movement is important. In this paper, a model describing the interaction between soil and an EPB shield used in tunnels is presented, based on the classical elastic theory of Mindlin. In this model, the changing location of the working shield is considered. The equations describing the ground deformation around the tunnel caused by the additional force on the shield working surface and the frictional force between the outer surface of the shield and the surrounding soil are derived. The ground deformation caused by ground loss due to shield tunnel construction is derived using stochastic medium theory. Finally, this model is applied to two running tunnels, and the sensitivity of the ground deformation to the calculation parameters is discussed.

Serine Proteases of Parasitic Helminths

Yong Yang,Yun jun Wen,Ya Nan Cai,Isabelle Vallee,Pascal Boireau,Ming Yuan Liu,Shi Peng Cheng 대한기생충학열대의학회 2015 The Korean Journal of Parasitology Vol.53 No.1

Optimal Design and Dynamic Control of Construction Dewatering with the Consideration of Dewatering Process

Cheng-hua Shi,Cheng-yong Cao,Ming-feng Lei,Li-min Peng,Jing Jiang 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.4

Design optimization of construction dewatering has important values in protecting the surrounding environment and reducing the engineering cost. The existing dewatering design methods are mostly based on the optimization of pumping rate needed to maintain a stable water level, while the drop and rise of water level are not considered in the estimation of pumping rate and dewatering time. The dynamics process of construction dewatering is taken into account in this article. The method for calculating the total water yield and dewatering time from the initial groundwater level to the target water level is established. Then, the design optimization of well group dewatering is provided with the consideration of total water yield and dewatering time in dynamic dewatering process. Finally, the method for the calculation of total water yield and dewatering time when dewatering regions change is derived. The proposed method can realize design optimization and dynamic control of dewatering as the dewatering regions and water level changes in construction. The reliability of this method is verified in on-site engineering applications.

Research on the Critical Condition of Brittle-Ductile Transition about Micro-Milling of KDP Crystal and Experimental Verification

Yong Xiao,Ming-Jun Chen,Yan-Ting Yang,Jian Cheng 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

KDP crystal is a kind of brittle material, and improper selection of processing parameter can easily result in brittle domain cuttingof KDP crystal. Determining the critical cutting depth of micro-milling brittle-ductile transition of KDP crystal can guide the selectionof process parameters. The elastic-plastic contact formula of blunt spherical indenter and brittle materials is used to explicate thecontact of micro-cutter edge and brittle materials. Combined with indentation critical load equation, the calculation model ofpredicting the critical cutting depth is established. The critical cutting depth is the function of material properties of the workpiece,the tool material properties and the tool edge radius. The edge radius of CBN flat end milling cutter is measured by atomic forcemicroscopy, and then the critical cutting depth of the KDP crystal material is calculated as 230 nm. By using this milling cutter, microgroovemilling experiments are conducted with different spindle speeds and feeds. The results demonstrate that as the spindle speedincreases, the micro-groove bottom surface gradually transformed from the brittle cutting state to plastic cutting state. The criticalspindle speed is 30000 rpm, and the maximum deformed cutting thickness is 227 nm, which coincides with the result of the theoreticalcalculation model.

Compatibility analysis between DTV and radio microphones in Korea

Yan-Ming Cheng,Yong-Sup Shim,Ho-Kyung Son,Hyun-Jin Hong,Il-Kyoo Lee 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.6

Recently, Korea has made a plan to allocate CH 14~ CH 51(470 MHz-698 MHz) for DTV. Therefore, it is necessary to take into account compatibility and sharing between DTV and other potential service systems. This paper assumes that DTV operates on CH 51 (692 MHz~ 698 MHz) and radio microphones operate on CH 52 (698 MHz~704 MHz) in spare band, and then analyzes compatibility between DTV and radio microphones. According to interference scenarios, protection requirements and system parameters, the required protection distances between DTV and radio microphone are determined. In the case of DTV potentially interferes with radio microphone, in the worst case, the required protection distance between DTV and radio microphone should be more than 1710.6 m for indoor scenario and 168.1 km for outdoor scenario; in the reverse case that radio microphone potentially interferes with DTV, the required protection distance between radio microphone and DTV should be more than 53 m for outdoor scenario. The analysis results may offer a reference and be helpful for considering compatibility between DTV and radio microphones in band V before DTV will be used.