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24 results on '"Hou, Minglei"'

11. Elevated Temperature-Induced Epimicrobiome Shifts in an Invasive Seaweed Gracilaria vermiculophylla

Author

Düsedau, Luisa, Ren, Yifei, Hou, Minglei, Wahl, Martin, Hu, Zi-Min, Wang, Gaoge, Weinberger, Florian, Düsedau, Luisa, Ren, Yifei, Hou, Minglei, Wahl, Martin, Hu, Zi-Min, Wang, Gaoge, and Weinberger, Florian

Abstract

Epibacterial communities on seaweeds are affected by several abiotic factors such as temperature and acidification. Due to global warming, surface seawater temperatures are expected to increase by 0.5–5 °C in the next century. However, how epibacterial communities associated with seaweeds will respond to global warming remains unknown. In this study, we investigated the response of epibacterial communities associated with the invasive Gracilaria vermiculophylla exposed to 3 °C above ambient temperature for 4 months using a benthocosm system in Kiel, Germany, and 16S rRNA gene amplicon sequencing. The results showed that elevated temperature affected the beta-diversity of the epibacterial communities. Some potential seaweed pathogens such as Pseudoalteromonas, Vibrio, Thalassotalea, and Acinetobacter were identified as indicator genera at the elevated temperature level. Thirteen core raw amplicon sequence variants in the elevated temperature group were the same as the populations distributed over a wide geographical range, indicating that these core ASVs may play an important role in the invasive G. vermicullophylla. Overall, this study not only contributes to a better understanding of how epibacterial communities associated with G. vermiculophylla may adapt to ocean warming, but also lays the foundation for further exploration of the interactions between G. vermiculophylla and its epimicrobiota.

Published
2023
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12. Analysis of the Soil Loss and Settlement of Silty Clay with Different Subclassifications

Author

Xiang-gang Wang, Hou Minglei, Lei Chen, Keqi Liu, and Wantao Ding

Subjects
Hydrogeology, Deformation (mechanics), Settlement (structural), Soil Science, Geology, Excavation, Subgrade, Geotechnical Engineering and Engineering Geology, Dispersion (geology), Architecture, Range (statistics), Geotechnical engineering, Stratum
Abstract

There is an ever-growing demand for the construction of silty clay stratum tunnels; therefore, effectively controlling the surface settlement caused by tunnel construction has become an important task. Since the physical indexes of silty clay greatly influence strength and deformation, based on the physical and mechanical indexes of 3192 groups in three areas, quantitative and determinative indexes for the subclassification of silty clay are proposed using K-means clustering and the tracking records of the actual project. Then, the soil loss and settlement of different subclassifications of silty clay are studied through the standard Gauss error function. Empirical formulas for calculating the width of the settlement trough and the soil loss rate are proposed. The dispersion of the settlement parameters with different subclassifications indicates that the soil properties of the silty clay strata vary greatly with subclassification, and the influence range of the surrounding soil disturbance caused by excavation also varies. In addition, the change in the soil loss rate with the propulsion of the tunnel face in the same monitoring section is discussed. For subgrade V, the increasing soil loss rate reaches a maximum when the tunnel face reaches the monitoring sections. For subgrades VI1 and VI2, this rate changes mainly during the timeframe spanning from 5 days before excavation to 5 days after excavation. A numerical simulation was also carried out to validate the applicability of the Peck formula for silty clay tunnels. The numerical prediction and field measured data show that when the cover-to-diameter ratio is between 1 and 3, it is reasonable to use the Peck formula to analyze the surface settlement of a silty clay tunnel. This paper can provide guidance based on experience for the subclassification of the soil surrounding rock and for the prediction of the ground surface settlement.

Published
2020

14. Experimental Study on the Deterioration Rules of Anchoring Performance of Rock Mass under Different Joints Distribution

Author

Keqi Liu, Chen Lei, Wantao Ding, Hou Minglei, Rui Chen, Mingbin Wang, and Wang Yang

Subjects
Materials science, Article Subject, Bar (music), Bond strength, 0211 other engineering and technologies, Anchoring, 02 engineering and technology, Corrosion, lcsh:TA1-2040, 021105 building & construction, Pitting corrosion, Composite material, lcsh:Engineering (General). Civil engineering (General), Rock mass classification, Joint (geology), 021101 geological & geomatics engineering, Civil and Structural Engineering
Abstract

In order to analyze the influence of damage caused by corrosion on anchoring performance of a rock mass with different joints, the anchored rock mass specimens with different joints distribution were prepared. An electrochemical accelerated corrosion test of specimens was carried out, and the mechanical test of them under different corrosion time was also investigated. The results showed that the pitting corrosion is the main form of the anchor bar corrosion of an anchoring rock mass with different joints, and the shape of the etch pit is reverse semi-ellipse. With the increase of pitting ratio, the ultimate bond strength and the corresponding slide distance decrease gradually. The effects of pitting ratio on the slide distance of the anchor bar in an anchored joint rock mass are insignificant, but these on the bond strength of it are significant. The bond-slide model of the anchored joint rock mass with different pitting ratios was established. The research results of this paper can provide reference for analyzing the corrosion damage of a complex anchored joint rock mass in practical engineering and a theoretical basis for the design optimization of anchoring support in the complex jointed rock mass.

Published
2019

15. Face stability analysis of shallow circular tunnels driven by a pressurized shield in purely cohesive soils under undrained conditions

Author

Li Mingjiang, Wantao Ding, Shi Peihe, Keqi Liu, and Hou Minglei

Subjects
Mechanism (engineering), Limit analysis, Face (geometry), Shield, Numerical analysis, Collapse (topology), Geotechnical engineering, Kinematics, Geotechnical Engineering and Engineering Geology, Stability (probability), Geology, Computer Science Applications
Abstract

Based on the slip line and limit analysis theories, this paper presents a new 3D collapse mechanism to analyze the face stability of a circular shield-driven tunnel in purely cohesive soil. The new collapse mechanism is a 4-variable multizone mechanism that depends on cover-to-diameter ratios (C/D). The proposed mechanism suggests that failure zones at the tunnel face are primarily formed by shear failure. A comparison of this approach with numerical methods and other kinematic approaches shows that the proposed failure mechanism significantly improves the existing upper-bound solutions for the face stability of circular tunnels in purely cohesive soils.

Published
2019

16. Upper-bound solutions for face stability of circular tunnel in purely cohesive soil using continuous rotational velocity field

Author

Wantao Ding, Shi Peihe, Lewen Zhang, Li Mingjiang, Hou Minglei, and Keqi Liu

Subjects
Mathematical model, 0211 other engineering and technologies, Geometry, Angular velocity, 02 engineering and technology, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, 01 natural sciences, Upper and lower bounds, Limit analysis, Lateral earth pressure, Transition zone, Terzaghi's principle, Geology, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Civil and Structural Engineering, Degree Rankine
Abstract

This paper presents a 2D analysis model based on limit analysis and slip-line theories for the face stability of a circular tunnel in purely cohesive soil. The analysis model depends on the ratio of cover depth C to tunnel diameter D. When C/D is equal to 0.5, the mechanism consists of three blocks, namely, Zone I, Zone II, and Zone III. When C/D is greater than 0.5, the mechanism consists of four blocks, namely, Zone I, Zone II, Zone III, and a possible Zone IV. Zone II is a transition zone satisfying the normality conditions. The possible Zone IV is a Rankine zone that is subjected to the influence of the vertical soil arching effect appearing at the top of Zone III. The criterion for the collapse thickness limit of the tunnel is proposed based on Terzaghi’s theory of relative soil pressure. The results show that significant improvements have been made to the existing solutions using the proposed failure mechanism for the face stability of circular tunnels in purely cohesive soil.

Published
2018

18. Shifting chemical defence or novel weapons? A review of defence traits in Agarophyton vermiculophyllum and other invasive seaweeds

Author

Wang, Gaoge, Ren, Yifei, Wang, Shasha, Hou, Minglei, Weinberger, Florian, Wang, Gaoge, Ren, Yifei, Wang, Shasha, Hou, Minglei, and Weinberger, Florian

Abstract

Seaweed bioinvasions increasingly affect coastal environments around the world, which increases the need for predictive models and mitigation strategies. The biotic interactions between seaweed invaders and invaded communities are often considered a key determinant of invasion success and failure and we here revise the current evidence that the capacity of seaweed invaders to deter enemies in newly reached environments correlates with their invasion success. Particularly efficient chemical defences have been described for several of the more problematic seaweed invaders during the last decades. However, confirmed cases in which seaweed invaders confronted un-adapted enemies in newly gained environments with deterrents that were absent from these environments prior to the invasion (so-called “novel weapons”) are scarce, although an increasing number of invasive and non-invasive seaweeds are screened for defence compounds. More evidence exists that seaweeds may adapt defence intensities to changing pressure by biological enemies in newly invaded habitats. However, most of this evidence of shifting defence was gathered with only one particular model seaweed, the Asia-endemic red alga Agarophyton vermiculophyllum, which is particularly accessible for direct comparisons of native and non-native populations in common garden experiments. A. vermiculophyllum interacts with consumers, epibionts and bacterial pathogens and in most of these interactions, non-native populations have rather gained than lost defensive capacity relative to native conspecifics. The increases in the few examined cases were due to an increased production of broad-spectrum deterrents and the relative scarcity of specialized deterrents perhaps reflects the circumstance that seaweed consumers and epibionts are overwhelmingly generalists.

Published
2021

20. Pre-supporting mechanism and supporting scheme design for advanced small pipes in the silty clay layer

Author

Wantao Ding, Li Huiliang, Hou Minglei, Keqi Liu, Gong Yingjie, and Shucai Li

Subjects
Pipe support, Bearing (mechanical), Settlement (structural), 0211 other engineering and technologies, Excavation, 02 engineering and technology, Building and Construction, Subgrade, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, 01 natural sciences, law.invention, Shear strength (soil), law, Geotechnical engineering, Arch, Water content, Geology, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences
Abstract

This study presents a design method for the advanced support of subway tunnels for different water content conditions in the silty clay layer. The influence of particle size distribution and water content on the mechanical properties of silty clay is studied through laboratory tests. In addition to the actual construction of the Harbin subway with a silty clay layer, a numerical calculation model is established to study the surface settlement, crown settlement, and supporting structure internal force during the tunnel excavation and support process under different working conditions. Furthermore, the mechanism of action of the advanced small pipe support is clearly defined, and a stability analysis model of the top and bench excavation in a silty clay layer is proposed to evaluate the stability of the tunnel face. The necessity and rationality of the pre-support is quantitatively analysed using the stability coefficient. The laboratory tests illustrate that within a certain range of clay content, the shear strength of silty clay decreases with an increase in water content. The silty clay was further divided into subgrades. The pre-support transfers the loose soil load to the initial support, which improves the early utilization of the lining structure. The advanced small pipe grouting increases the range of the bearing arch, shortens the interval distance of the supporting arch feet, and reduces the vertical load acting on the tunnel face. For the condition of subgrade V in silty clay strata, the stability of the tunnel face can be maintained without the advanced small pipe support. For the condition of subgrade VI1, the advanced small pipe support must be applied to ensure the stability of the tunnel face, but the grouting reinforcement measures are not required. For the condition of subgrade VI2, the advanced small pipe support and grouting reinforcement must be used simultaneously to ensure the stability of the tunnel face.

Published
2020

22. Shifting chemical defence or novel weapons? A review of defence traits in Agarophyton vermiculophyllumand other invasive seaweeds

Author

Wang, Gaoge, Ren, Yifei, Wang, Shasha, Hou, Minglei, and Weinberger, Florian

Abstract

Seaweed bioinvasions increasingly affect coastal environments around the world, which increases the need for predictive models and mitigation strategies. The biotic interactions between seaweed invaders and invaded communities are often considered a key determinant of invasion success and failure and we here revise the current evidence that the capacity of seaweed invaders to deter enemies in newly reached environments correlates with their invasion success. Particularly efficient chemical defences have been described for several of the more problematic seaweed invaders during the last decades. However, confirmed cases in which seaweed invaders confronted un-adapted enemies in newly gained environments with deterrents that were absent from these environments prior to the invasion (so-called “novel weapons”) are scarce, although an increasing number of invasive and non-invasive seaweeds are screened for defence compounds. More evidence exists that seaweeds may adapt defence intensities to changing pressure by biological enemies in newly invaded habitats. However, most of this evidence of shifting defence was gathered with only one particular model seaweed, the Asia-endemic red alga Agarophyton vermiculophyllum, which is particularly accessible for direct comparisons of native and non-native populations in common garden experiments. A. vermiculophylluminteracts with consumers, epibionts and bacterial pathogens and in most of these interactions, non-native populations have rather gained than lost defensive capacity relative to native conspecifics. The increases in the few examined cases were due to an increased production of broad-spectrum deterrents and the relative scarcity of specialized deterrents perhaps reflects the circumstance that seaweed consumers and epibionts are overwhelmingly generalists.

Published
2021
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