In-site Experiments on the Swelling Characteristics of a Shield Tunnel in Expansive Clay: A Case Study

Jianxiu Wang,Jiaxing Liu,Xiaotian Liu,Yunhua Jiang,Xuezeng Liu 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.3

Expansive soil swells, softens, and disintegrates when absorbing water, whereas it shrinks when losing water. Understanding the swelling characteristics of a shield tunnel in expansive soil is important. However, most in-site experiences on the swelling characteristics of a tunnel are obtained from the NATM tunnels constructed in swelling rock using drill and blast method; most laboratory experiments or theoretical analyses on the swelling characteristics of a shield tunnel in expansive soil are under certain hypotheses which have not been verified in actual situation. To solve the problems, the Slender West Lake tunnel was selected as the background, laboratory and in-site experiments were performed to understand the swelling characteristics of a shield tunnel in expansive clay. Four experimental sections were constructed in the actual tunnel. The measuring gauges were pre-installed in the segments in factory and the segments were installed in-site to observe the actual earth pressure and temperature during construction. The influences of expansive soil to the distributions and variations of earth pressure, bending moment, and temperature were analyzed. The increasing earth pressure was divided into three stages. Large earth pressure was detected at the top, bottom, left, and right sides of the tunnel. The earth pressure at the left and right sides was larger than that at the top and bottom. Large negative bending moment was detected at the top and bottom of the tunnel, whereas large positive bending moment was detected at the left and right sides of the tunnel. The minimum bending moment appeared at 45° oblique. The largest negative bending moment was larger than the largest positive bending moment. Based on the observations, a load mode of swelling pressure for a beam-spring model was suggested. It can be referred by the similar tunnels.

Dewatering of a 32.55 m Deep Foundation Pit in MAMA Under Leakage Risk Conditions

Jianxiu Wang,Xiaotian Liu,Jiaxing Liu,Linbo Wu,Qingfeng Guo,Qian Yang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.8

A 2,250 mm whirlpool foundation pit is located in Donghai Island, Zhanjiang City, Guangdong Province, China. The layers of theisland are composed of multi-aquifers and multi-aquitards (MAMA). The aquifers are intersected by partial aquitard lenses. A largeconfined aquifer is frequently interbedded and separated into several sub-confined aquifers by partial aquitards. In the 2,250 mmfoundation pit, the water level of two confined aquifers was reduced to satisfy excavation requirements and prevent water inrush. Construction of the 32.55 m deep foundation pit encountered MAMA and potential defects of the diaphragm wall. The pumpingwells in the second confined aquifer were used to reduce the water level to ensure the safety of bottom excavation. The pumpingwells in the first confined aquifer were used to reduce the water level under emergency conditions to prevent potential water inrushand piping from the defects of the diaphragm wall. Field pumping tests and numerical simulations were performed to determine therisk of leakage and verify the capability of the pumping wells to reduce the water level. Quicksand occurred during shallowexcavation because of leakage although the confined aquifer had been cut off and pumped for a long time. Three pumping wells wereinstalled to reduce the water level. When the foundation pit was excavated to a depth of 24 m, water inrush occurred at the middle ofthe pit bottom although the water level of the dewatered aquifer had been reduced to below the excavation face. A 90 m deepborehole was found where the underlying confined aquifer below the first aquifer induced the water inrush. Although the upper waterlevel was reduced, the high water level in the deep part still induced water inrush. The pumping wells in the second aquifer were allopened, and the water level of the underlying confined aquifer was reduced. After the water level was reduced to below the pitbottom, the borehole was filled, and the water inrush stopped. However, water inrush occurred on the cracks of the diaphragm wall aspredicted. The pre-installed pumping wells were opened to control the water inrush. The deepest foundation pit on the island wasconstructed successfully after dealing with the water inrush and leakages.

Numerical simulation of a toroidal single-phase natural circulation loop with a k-k-ω transitional turbulence model

Geng Yiwa,Liu Xiongbin,Li Xiaotian,Zhang Yajun 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

The wall friction correlations of oscillatory natural circulation loops are highly loop-specific, making it difficult to perform 1-D system simulations before obtaining specific experimental data. To better predict the friction characteristics, the nonlinear dynamics of a toroidal single-phase natural circulation loop were numerically investigated, and the transition effect was considered. The k-kL-ω transitional turbulence and k-ω SST turbulence models were used to compute the flow characteristics of the loop under different heating powers varying from 0.48 to 1.0 W/cm2, and the results of both models were compared with previous experiments. The mass flow rates and friction factors predicted by the k-kL-ω model showed a better agreement with the experimental data than the results of the k-ω SST model. The oscillation frequencies calculated using both models agreed well with the experimental data. The k-kL-ω transitional turbulence model provided better friction-factor predictions in oscillatory natural circulation loops because it can reproduce the temporal and spatial variation of the wall shear stress more accurately by capturing the movement of laminar, transition turbulent zones inside unstable natural circulation loops. This study shows that transition effects are a possible explanation for the highly loop-specific friction correlations observed in various oscillatory natural circulation loops.

Shift robust control during inertia phase for random disturbance load

Guoxiang Cao,Anlin Wang,Xiaotian Liu,Donghuan Xu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

The automatic transmission of earthmoving machinery generally has problems of shifting shock and poor control robustness. Low-frequency high-energy random loads and large-space model uncertainties are the main causes of these problems. Therefore, we considered a type of wheel loader automatic transmission as the research object and propose a robust control method for the shifting inertia phase of the earthmoving machinery automatic transmission. The control method includes a robust controller b K , a disturbance compensation controller d K and a feedforward compensator f K . The robust controller b K is designed by μ synthesis method to resist the uncertainties of parameters and structure and guarantee the output speed to track the reference input. A load dynamic estimation method for random disturbance load of automatic transmission is proposed, which improves the compensation effect of disturbance compensation controller d K . The feedforward compensator f K is used to eliminate the influence of the reference input on the system. The above control methods were applied to the whole machine simulation platform of a certain type of wheel loader, and the random disturbance load of the measured under real working conditions was taken as input load. Under the conditions of no-load, half-load and full load, the control method has good smoothness and strong robustness. This paper has reference value for solving the inertial phase shift robust control of transmission under random disturbance load.

Identification and Screening of Gene(s) Related to Susceptibility to Enterotoxigenic Escherichia coli F4ab/ac in Piglets

Li, Hejun,Li, Yuhua,Qiu, Xiaotian,Niu, Xiaoyan,Liu, Yang,Zhang, Qin Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.4

In 2004, Jorgensen and coworkers proposed the MUC4 gene as a candidate gene of enterotoxigenic Escherichia coli (ETEC) F4ab/ac receptor in piglets and a mutation of $G{\rightarrow}C$ in intron 7 of MUC4 was identified to be associated with the ETEC F4ab/ac adhesion phenotypes. In this study, we used 310 piglets of three breeds (Landrace, Large White and Chinese Songliao Black) to analyze the relationship between this mutation and the F4ab/ac adhesion phenotype. The results show that the genotypes at this site and the ETEC F4ab/ac adhesion phenotypes were not completely consistent, although they are very strongly associated. Among the individuals with genotype CC, which was identified as a resistant genotype to F4ab/ac adhesion, only 72.1% (124/172) were non-adhesive to ETEC F4ab and 77.9% (134/172) were non-adhesive to ETEC F4ac infections. This suggests that this mutation may not be the causative mutation for ETEC F4ab/ac adhesion, rather, the actual causative mutation may be in another gene closely linked to MUC4, or at aother site within the MUC4 gene. Our results also suggest that the receptors of F4ab and F4ac may be determined by two different but closely linked loci. In order to screen other genes related to F4ab/ac adhesion in piglets, the mRNA profiles from six full sib piglets, of which three were adhesive to ETEC F4ab/ac and three non-adhesive, were analyzed by suppression subtractive hybridization (SSH). One up-regulated gene, Ep-CAM, was selected for further analysis based on its role in the intestinal epithelial cells adhesion. Using real-time RT-PCR, we found that the Ep-CAM gene was significantly up-regulated in the piglets adhesive to F4ab/ac. It was mapped to SSC3q11-q14 by radiation hybrid mapping.

A Flattop Radiation Pattern Antenna with Special‑Shaped Array Placement for Stadium Communications

Bing Ma,Tao Zhang,Wenjun Gao,Xiaotian Wang,Zhijia Liu 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

A fattop radiation pattern antenna with special-shaped array placement for large-scale stadium communications is presented in this paper. The antenna array consists of only 16 electric dipoles, each of that is±45° linear polarizations, placed in three rings confguration above a ground plane. Under the ground plane two feeding networks with±45° linear polarizations, respectively are used to divide signals to the 16 electric dipoles to produce fattop radiation patterns. A prototype operated at 2300–2700 MHz for stadium wireless communications, such as 4G LTE, is manufactured and tested, and good agreements between simulation and measurement are demonstrated. The measured gain is above 12 dBi and the side-lobe levels are lower than −20 dB. The measured isolations between the two polarization ports are less than −30 dB within the operating band. A fast beam ramp of less than 20° from −3 to −20 dB is achieved.

Molecular and Cellular Microbiology / Biomedical Sciences : Alteration of the Metabolome Profile in Endothelial Cells by Overexpression of miR-143/145

( Wenshuo Wang ),( Ye Yang ),( Yiqing Wang ),( Liewen Pang ),( Jiechun Huang ),( Hongyue Tao ),( Xiaotian Sun ),( Chen Liu ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.3

Communication between endothelial cells (ECs) and smooth muscle cells (SMCs) via miR-143/145 clusters is vital to vascular stability. Previous research demonstrates that miR-143/145 released from ECs can regulate SMC proliferation and migration. In addition, a recent study has found that SMCs also have the capability of manipulating EC function via miR-143/145. In the present study, we artificially increased the expression of miR-143/145 in ECs, to mimic a similar change caused by miR-143/145 released by SMCs, and applied untargeted metabolomics analysis, aimed at investigating the consequential effect of miR-143/145 overexpression. Our results showed that miR-143/145 overexpression alters the levels of metabolites involved in energy production, DNA methylation, and oxidative stress. These changed metabolites indicate that metabolic pathways, such as the SAM cycle and TCA cycle, exhibit significant differences from the norm with miR-143/145 overexpression.

Whole-genome sequence association study identifies cyclin dependent kinase 8 as a key gene for the number of mummified piglets

Wu Pingxian,Chen Dejuan,Wang Kai,Wang Shujie,Liu Yihui,Jiang Anan,Xiao Weihang,Jiang Yanzhi,Zhu Li,Xu Xu,Qiu Xiaotian,Li Xuewei,Tang Guoqing 아세아·태평양축산학회 2023 Animal Bioscience Vol.36 No.1

Objective: Pigs, an ideal biomedical model for human diseases, suffer from about 50% early embryonic and fetal death, a major cause of fertility loss worldwide. However, identifying the causal variant remains a huge challenge. This study aimed to detect single nucleotide polymorphisms (SNPs) and candidate genes for the number of mummified (NM) piglets using the imputed whole-genome sequence (WGS) and validate the potential candidate genes. Methods: The imputed WGS was introduced from genotyping-by-sequencing (GBS) using a multi-breed reference population. We performed genome-wide association studies (GWAS) for NM piglets at birth from a Landrace pig populatiGWAS peak located on SSC11: 0.10 to 7.11 Mbp (Top SNP, SSC11:1,889,658 bp; p = 9.98E-13) was identified in cyclin dependent kinase on. A total of 300 Landrace pigs were genotyped by GBS. The whole-genome variants were imputed, and 4,252,858 SNPs were obtained. Various molecular experiments were conducted to determine how the genes affected NM in pigs. Results: A strong GWAS peak located on SSC11: 0.10 to 7.11 Mbp (Top SNP, SSC11:1,889,658 bp; p = 9.98E-13) was identified in cyclin dependent kinase 8 (CDK8) gene, which plays a crucial role in embryonic retardation and lethality. Based on the molecular experiments, we found that Y-box binding protein 1 (YBX1) was a crucial transcription factor for CDK8, which mediated the effect of CDK8 in the proliferation of porcine ovarian granulosa cells via transforming growth factor beta/small mother against decapentaplegic signaling pathway, and, as a consequence, affected embryo quality, indicating that this pathway may be contributing to mummified fetal in pigs. Conclusion: A powerful imputation-based association study was performed to identify genes associated with NM in pigs. CDK8 was suggested as a functional gene for the proliferation of porcine ovarian granulosa cells, but further studies are required to determine causative mutations and the effect of loci on NM in pigs.