Numerical analysis on stability of express railway tunnel portal

Xiaojun Zhou,Hongyun Hu,Bo Jiang,Yuefeng Zhou,Yong Zhu 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1

On the basis of the geological conditions of high and steep mountainous slope on which an exit portal of an express railway tunnel with a bridge-tunnel combination is to be built, the composite structure of the exit portal with a bridge abutment of the bridge-tunnel combination is presented and the stability of the slope on which the express railway portal is to be built is analyzed using three dimensional (3D) numerical simulation in the paper. Comparison of the practicability for the reinforcement of slope with in-situ bored piles and diaphragm walls are performed so as to enhance the stability of the high and steep slope. The safety factor of the slope due to rockmass excavation both inside the exit portal and beneath the bridge abutment of the bridge-tunnel combination has been also derived using strength reduction technique. The obtained results show that post tunnel portal is a preferred structure to fit high and steep slope, and the surrounding rock around the exit portal of the tunnel on the high and steep mountainous slope remains stable when rockmass is excavated both from the inside of the exit portal and underneath the bridge abutment after the slope is reinforced with both bored piles and diaphragm walls. The stability of the high and steep slope is principally dominated by the shear stress state of the rockmass at the toe of the slope; the procedure of excavating rockmass in the foundation pit of the bridge abutment does not obviously affect the slope stability. In-situ bored piles are more effective in controlling the deformation of the abutment foundation pit in comparison with diaphragm walls and are used as a preferred retaining structure to uphold the stability of slope in respect of the lesser time, easier procedure and lower cost in the construction of the exit portal with bridge-tunnel combination on the high and steep mountainous slope. The results obtained from the numerical analysis in the paper can be used to guide the structural design and construction of express railway tunnel portal with bridge-tunnel combination on high and abrupt mountainous slope under similar situations.

Advanced Stability Analysis of the Tunnels in Jointed Rock Mass Based on TSP and DEM

Hongyun Fan,Liping Li,Hongliang Liu,Shaoshuai Shi,Jie Hu,Shen Zhou 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4

The discrete element method (DEM) can analyze the large deformation and large displacement of rock mass effectively, and it is widely used in underground engineering, slope engineering and other fields. However, due to the low accuracy of rock mass structural surface information acquisition, the application of discrete element method in the analysis of jointed rock mass stability is still deviated. In this paper, combined with the advantages of the tunnel seismic prediction (TSP) in obtaining discontinuous geological interface information and the discrete element method in the calculation and analysis of jointed rock mass stability, this paper proposes an advanced analysis method for jointed rock mass stability based on TSP and DEM. Compared to the traditional methods, the analysis results of the jointed rock mass stability are more reliable. Firstly, relying on the advanced detection system – Tunnel Seismic Prediction 203Plus, the unstructured rock mass structure information of the tunnel is obtained, and the spatial attitude of the discontinuous geological interface is further determined. Secondly, based on the Fish programming language, the non-continuous geological interface information can be expressed in the discrete unit software – 3D Distinct Element Code (3DEC). In this way, the excavation calculation model of the tunnels in jointed rock mass can be constructed. Finally, based on the DEM, the excavation of the tunnels in jointed rock mass can be simulated, analyze the stability of surrounding rock during the tunnel excavation process, and realize the stability analysis of surrounding rock stability of jointed rock mass. Based on the Huangjiazhuang Tunnel Project, this paper uses the above method to carry out on-site application. The results show that the location of the dangerous block is predicted to be consistent with the actual exposure of the tunnel surrounding rock based on TSP and DEM, which verify the accuracy and feasibility of this method, and the research results have practical guiding significance for the safe construction of the tunnels in jointed rock mass.

The Mechanism of Rockbolt in the Jointed Rock Under Uniaxial Tension

Shen Zhou,Xiaoyu Ji,Li-Ping Li,Hong-liang Liu,Chun Zhu,Hongyun Fan,Qi Zhang,Caihua Shi,Xutong Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.11

In this research, the rockbolt mechanism of a jointed rock mass under uniaxial tension was systematically revealed with a laboratory test and a numerical simulation. It was found that the rockbolt rock mass experienced five stages under uniaxial tension, the densification stage, elastic stage, plastic deformation stage, progressive debonding stage, and complete debonding stage. The stress-strain curve and ultimate tensile strength of a rockbolt rock mass were analyzed by taking the rockbolt spacing and rockbolt angle as variables. It was found that the improvement effect of the reduction of the rockbolt spacing on the ultimate tensile strength was limited. When the rockbolt spacing was reduced to a certain limit, the stress concentration area between adjacent rockbolts was connected and destroyed, resulting in the increase of the rockbolt rock strength becoming smaller, and even having a downward trend. The increase of the rockbolt angle led to the change of the stress mode and failure mode of the whole structure, and the ultimate tensile strength first increased and then decreased. The optimal rockbolt angle was between 60° and 70°. It is worth noting that there was an obvious mechanical occlusion between the thread on the rockbolt surface and the rock mass, resulting in the multi-stage step-down characteristic of the stress-strain curve in the complete debonding stage. The results of this study can provide a reference for the design and construction of similar projects.

Modified Renshen Wumei Decoction Alleviates Intestinal Barrier Destruction in Rats with Diarrhea

( Zhiwei Guan ),( Qiong Zhao ),( Qinwan Huang ),( Zhonghe Zhao ),( Hongyun Zhou ),( Yuanyuan He ),( Shanshan Li ),( Shifang Wan ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.9

Modified Renshen Wumei decoction (MRWD), a famous traditional Chinese medicine, is widely used for treating persistent diarrhea. However, as the mechanism by which MRWD regulates diarrhea remains unknown, we examined the protective effects of MRWD on intestinal barrier integrity in a diarrhea model. In total, 48 male rats were randomly distributed to four treatment groups: the blank group (CK group), model group (MC group), Medilac-Vita group (MV group) and Chinese herb group (MRWD group). After a 21-day experiment, serum and colon samples were assessed. The diarrhea index, pathological examination findings and change in D-lactate and diamine oxidase (DAO) contents illustrated that the induction of diarrhea caused intestinal injury, which was ameliorated by MV and MRWD infusion. Metabolomics analysis identified several metabolites in the serum. Some critical metabolites, such as phosphoric acid, taurine, cortisone, leukotriene B4 and calcitriol, were found to be significantly elevated by MRWD infusion. Importantly, these differences correlated with mineral absorption and metabolism and peroxisome proliferator-activated receptor (PPAR) pathways. Moreover, it significantly increased the expression levels of TLR4, MyD88 and p-NF-κB p65 proteins and the contents of IL-1 and TNF-α, while the expression levels of occludin, claudin-1 and ZO-1 proteins decreased. These deleterious effects were significantly alleviated by MV and MRWD infusion. Our findings indicate that MRWD infusion helps alleviate diarrhea, possibly by maintaining electrolyte homeostasis, improving the intestinal barrier integrity, and inhibiting the TLR4/NF-κB axis.

Effect of Panax ginseng and Fructus Mume on Intestinal Barrier and Gut Microbiota in Rats with Diarrhea

Mengjie Zhao,Qiong Zhao,Zhiwei Guan,Qianwei Liu,Hongyun Zhou,Qinwan Huang,Bixiu Huo 한국식품영양과학회 2023 Journal of medicinal food Vol.26 No.3

Panax ginseng and Fructus mume (Renshen Wumei in Chinese, RW) are natural medicines with high nutritional and pharmacological value. They have been widely used together in China to treat gastrointestinal diseases, especially persistent diarrhea, but the potential mechanisms remain elusive. In this study, a diarrhea model was established in rats using a 30% aqueous extract of senna. The therapeutic effects of RW were evaluated by recording the prevalence of loose stools, the diarrhea index, and histopathological changes in colon tissue. The levels of mucins, tight junction (TJ) proteins, inflammatory cytokines, and phosphoinositide 3-kinase/Akt/nuclear factor-κB (PI3K/Akt/NF-κB) signaling pathway proteins were measured. Metagenomic sequencing was used to analyze the gut microbiota. Treatment with RW alleviated injury to the intestinal barrier in rats with diarrhea and also upregulated levels of Muc2 and TJ proteins, such as occludin, zonula occludens-1, and claudin-1. Administration of RW regulated the structure of the gut microbiota in diarrheal rats. Furthermore, RW suppressed levels of interleukin (IL), tumor necrosis factor (TNF)-α, IL-1, PI3K, Akt, and p-NF-κB p65 and also increased IL-4 levels. Our study indicates that P. ginseng and Fructus mume help improve the symptoms of diarrhea, possibly by alleviating the intestinal barrier injury, regulating intestinal flora composition, and inhibiting the PI3K/Akt/NF-κB signaling pathway.