Parameter Sensitivity Analysis of a New Fabricated Rectangular Tunnel Joint Using Numerical Method

Zhen Huang,Chenlong Zhang,Shaokun Ma,Hai Zhang,Zhang Zhou,Hongzhou Li 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.2

An assembled rectangular tunnel has the advantages of high space utilization rate and strong urban applicability. This solution has been widely used in urban underground traffic construction. During their construction and operation, the joints are the weakest parts of the structure. The mechanical behavior of joints is closely related to the safety of the tunnel; thus, it is important to use a joint with good mechanical behavior. This study presents a new type of joints for shallow buried assembled rectangular tunnels. To evaluate the effect of design parameters (tenon depth and tenon angle) on the behavior of joints, the finite element method was used. At the same time, the mechanical behavior of rectangular tunnel joint was analyzed and compared with that of a traditional straight joint under the same loading conditions, showing better results. The performance-based engineering (PBE) concept was implemented to evaluate the robustness of rectangular tunnel joints. The results show that if the bolt is placed on the tensile side of the structure, it provides a strong restraining effect on the deformation of the joint. When the tenon depth and angle are 0.8 m and 3.6°, respectively, the overall behavior of the rectangular tunnel joint was improved. The new type of assembled rectangular tunnel joint designed in this study has a good application prospect in a shallow stratum and provides new ideas for the design and construction of such tunnels.

Discrete Element Simulation of Macro and Micro Mechanical Properties of Round Gravel Material under Triaxial Stress

Shaokun Ma,Haijun Huang,Fapai Tian,Jian Gong,Jiabing Zhang,Zhibo Duan 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.5

In this study, the effects of relative density and confining pressure on the shear characteristics of round gravel are investigated using a large-scale triaxial apparatus and the discrete element method. A simple and efficient numerical method for simulating flexible membranes is introduced. The results show that the stress-strain curves develop from hardened to softened type with increasing relative density, while the stress-strain curves develop from softened to hardened type with increasing confining pressure. As the axial strain increases, the strong contact force chains are vertically distributed, and the larger the relative density and confining pressure, the greater the number and thickness of the strong contact force chains. In the shear process, the distribution of average normal and tangential contact forces show “peanut-shaped” and “petal-shaped”, respectively. The increase in relative density increases the anisotropy of the specimen, while the increase in confining pressure results in a decrease. A linear relationship exists between the macroscopic stress ratio and the anisotropy coefficient. The anisotropy coefficient of the normal contact force provides the greatest contribution to the macroscopic shear strength (about 55%), followed by the anisotropy coefficient of the contact normal (about 26%) and that of the tangential contact force (about 19%).

Comparison of formation of bubbles and droplets in step-emulsification microfluidic devices

Wei Zhang,Ziwei Liu,Shaokun Jiang,Chunying Zhu,Youguang Ma,Taotao Fu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-

Monodispersed microbubbles and microdroplets are widely used as reaction carriers in microfluidics. Inthis study, the generation processes of bubbles and droplets in a step-emulsification microfluidic deviceare compared to show the similarities and differences in the emulsification process. By changing theplacement of the microdevice, the effects of buoyancy and gravity on the generation of bubbles and dropletsare introduced, and the feedback mechanism of the bubble layer and the effect of droplet accumulationon the emulsification process are clarified. Finally, based on the analysis of the difference of thepinch-off of the dispersed phase between the bubble and the droplet in this configuration, the Plateau-Rayleigh instability processes for the formation of bubble and droplet are revealed by using a highspeedcamera system, and the reasons for the difference of the operating ranges of the gas flow rateand liquid flow rate in the dripping flow regime are explained.

Bubble formation in a step-emulsification microdevice: hydrodynamic effects in the cavity

Zhiwei Zhang,Zhongdong Wang,Fengrui Bao,Mengyu Fan,Shaokun Jiang,Chunying Zhu,Youguang Ma,Taotao Fu 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-

This study focuses on the generation of bubbles in a step-emulsification microdevice via a two-anglephotography method. It's found that the bubble generation mechanism is controlled by the interfacialtension, below a critical capillary number; while controlled by viscous force, inertial force and thedisturbance induced by the bubble swarm, above the critical capillary number. From the two-anglephotography method, a model is established for predicting the bubble size, by taking into account of thedynamic contact angle between gas-liquid interface and wall, and the hydrodynamic feedback of thecavity on bubble formation via the quantification of resistance by the volume fraction of gas in the cavity.

Deformation Response Induced by Surcharge Loading above Shallow Shield Tunnels in Soft Soil

Zhen Huang,Hai Zhang,Helin Fu,Shaokun Ma,Ying Liu 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.8

In the case of sudden surcharge loading, shallow shield tunnels in areas with soft soil experience substantial deformation responses. It is very important to understand the different loading modes and control measures above the shallow shield tunnels in soft soil for improving the safety of tunnel structure and reducing the influence of deformation. In this study, a three-dimensional numerical model of shallow shield tunnels in soft soil is established with FLAC3D. Ground and tunnel deformations are analyzed under different loading modes, and the effects of different deformation control measures are also studied. The numerical simulations in this paper show that the surface and tunnel deformation responses vary when induced by different loading modes above shallow shield tunnels in soft soil. After surface hardening with a 20-cm-thick layer of C20 concrete, the surface settlement is effectively controlled, and the uneven longitudinal settlement of the tunnel vault is improved. However, controlling the height of the surcharge is the most direct deformation control method. When the height of the surcharge is reduced from 6 m to 4 m and 2 m, the maximum ground settlement is reduced by 37.8% and 69.4%, respectively, and the maximum longitudinal settlement of the tunnel vault is reduced by 35.3% and 65.2%, respectively. During the operation of shallow shield tunnel in soft soil area, sudden surcharge loading should not be allowed. In the inevitable case, the surcharge loading on one side of the tunnel should be prevented and the surcharge loading height should be strictly limited.

Controllable synthesis of zinc oxide with ionic liquid and supramolecular gel as co-template for the degradation of organic dyes

Zhen Li,Lili Sun,Jie Zhang,Shaokun Tang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Zinc oxide was synthesized with ionic liquid tetramethylammonium glycine ([N1111][Gly]) and supramoleculargel N-lauro-L-glutamic acid-di-n-butylamide (GP-1) as co-template by solvothermal method and characterized byX-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-visdiffuse reflectance spectrometer. The effects of templating agent dosage and aging time on the morphology, mesoporousstructure, and crystal phase of ZnO were investigated. The results demonstrate that the ionic liquid [N1111][Gly]and GP-1 organogel synergistically control the growth orientation of the crystal, and the morphology of ZnO varies withthe templating agent dosage and aging time. The as-synthesized samples were applied in the catalytic degradation ofCongo red under simulated solar light irradiation. In particular, the synthesized sample (MZ-3-8) with nanosheets morphologyexhibited the best catalytic performance with a degradation rate up to 98% for 90 min, clearly superior to commercialZnO and P-25. Furthermore, the catalyst can be cycled at least eight times with little loss of photocatalytic activity.

Giant Ganglioneuroma of Thoracic Spine : A Case Report and Review of Literature

Huang, Yong,Liu, Lidi,Li, Qiao,Zhang, Shaokun The Korean Neurosurgical Society 2017 Journal of Korean neurosurgical society Vol.60 No.3

Ganglioneuroma (GN) is a rare benign tumor of neural crest origin usually found in the abdomen, but may occasionally present at uncommon sites including the cervical, lumbar, or sacral spine. However, GNs of thoracic spine are extremely rare. In this report, we describe a 12-year-old girl with giant GN in the thoracic spine, who underwent successful resection (T1-4 level) of the tumor. Histopathological examination confirmed the diagnosis. GN should be considered in the differential diagnosis of any paraspinal mass. A high index of suspicion and correlation of clinico-radiological findings is necessary in differentiating a large benign tumor from a malignant growth. Complete surgical excision is the treatment of choice; however tumor size and location need to be considered for the surgical approach (one-step or multiple surgeries). Close follow-up after surgery is mandatory.

Can CD44+/CD24- Tumor Cells Be Used to Determine the Extent of Breast Cancer Invasion Following Neoadjuvant Chemotherapy?

Hong Wu,Ruhui Li,XiaoDong Hang,Ming Yan,Feng Niu,Lidi Liu,Wei Liu,Song Zhao,Shaokun Zhang 한국유방암학회 2011 Journal of breast cancer Vol.14 No.3

Purpose: To investigate the distribution of CD44+/CD24- cells in breast cancers in relation to tumor size before and after the administration of neoadjuvant chemotherapy. Methods: CD44+/CD24- tumor cells obtained from breast cancer specimens were characterized in vivo and in vitro using tumor formation assays and mammosphere generation assays, respectively. The distribution of CD44+/CD24- tumor cells in 78 breast cancer specimens following administration of neoadjuvant chemotherapy was also evaluated using immunofluorescence assays, and this distribution was compared with the extent of tumor invasion predicted by Response Evaluation Criteria in Solid Tumours (RECIST). Results: In 27/78 cases, complete remission (CR) was identified using RECIST. However, 18 of these CR cases were associated with a scattered distribution of tumor stem cells in the outline of the original tumor prior to neoadjuvant chemotherapy. After neoadjuvant chemotherapy, 24 cases involved cancer cells that were confined to the tumor outline, and 21 cases had tumor cells or tumor stem cells overlapping the tumor outline. In addition, there were 6 patients who were insensitive to chemotherapy, and in these cases, both cancer cells and stem cells were detected outside the contours of the tumor volume imaged prior to chemotherapy. Conclusion:CD44+/CD24- tumor cells may be an additional parameter to evaluate when determining the extent of breast cancer invasion.