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246 results on '"Lei, Huayang"'

61. Influencing factors and control measures of excavation on adjacent bridge foundation based on analytic hierarchy process and finite element method

Author

Lei Huayang, Haiyan Jin, Wan Yongfeng, Feng Shuangxi, and Han Jun

Subjects
Computer science, Settlement (structural), Foundation (engineering), Analytic hierarchy process, Excavation, 02 engineering and technology, 01 natural sciences, Civil engineering, Bridge (interpersonal), Finite element method, 010101 applied mathematics, 020303 mechanical engineering & transports, 0203 mechanical engineering, Architecture, 0101 mathematics, Engineering design process, Pile, Civil and Structural Engineering
Abstract

Many uncertain factors in the excavation process may lead to excessive lateral displacement or overlimited internal force of the piles, as well as inordinate settlement of soil surrounding the existing bridge foundation. Safety control is pivotal to ensuring the safety of adjacent structures. In this paper, an innovative method is proposed that combines an analytic hierarchy process (AHP) with a finite element method (FEM) to reveal the potential impact risk of uncertain factors on the surrounding environment. The AHP was adopted to determine key influencing factors based on the weight of each influencing factor. The FEM was used to quantify the impact of the key influencing factors on the surrounding environment. In terms of the AHP, the index system of uncertain factors was established based on an engineering investigation. A matrix comparing the lower index layer to the upper index layer, and the weight of each influencing factor, were calculated. It was found that the excavation depth and the distance between the foundation pit and the bridge foundation were fundamental factors. For the FEM, the FE baseline model was calibrated based on the case of no bridge surrounding the foundation pit. The consistency between the monitoring data and the numerical simulation data for a ground settlement was analyzed. FE simulations were then conducted to quantitatively analyze the degree of influence of the key influencing factors on the bridge foundation. Furthermore, the lateral displacement of the bridge pile foundation, the internal force of the piles, and the settlement of the soil surrounding the pile foundation were emphatically analyzed. The most hazardous construction condition was also determined. Finally, two safety control measures for increasing the numbers of support levels and the rooted depths of the enclosure structure were suggested. A novel method for combining AHP with FEM can be used to determine the key influencing aspects among many uncertain factors during a construction, which can provide some beneficial references for engineering design and construction.

Published
2021

62. Application and design method of dredging sludge ground treated via prefabricated radiant drain vacuum preloading.

Author

Feng, Shuangxi, Lei, Huayang, Liu, Anyi, Dai, Shitao, Ma, Tianlu, and Lei, Zheng

Subjects
*PORE water pressure, *VERTICAL drains, *DREDGING, *RADIANT heating, *WATER pressure, *DREDGES, *SUPERRADIANCE
Abstract

The high-water-content sludge produced through dredging seriously restricts marine ecological environments. Vacuum preloading methods (involving prefabricated vertical drains (PVDs)) are widely used to dewater and consolidate sludge ground, but these methods require long treatment periods and have deprived reinforcement effects. To overcome the limitations of PVD vacuum preloading, a prefabricated radiant drain (PRD) vacuum preloading method is proposed is this study by adding a prefabricated horizontal drain (PHD) to the PVD framework. Physical model tests are conducted under PVD and PRD vacuum preloading conditions, and a large-strain three-dimensional finite element (FE) model is established and validated against the physical model test data. FE parametric analyses are also conducted to evaluate the key factors influencing the PRD, i.e., the PHD length and spacing. The results show that the reinforcement effect of PRD vacuum preloading is better than that of PVD vacuum preloading. The ground settlement effect increases as the PHD length increases and the PHD spacing decreases. The settlement and pore water pressure metrics show elliptical distributions with an increasing PHD length. Through this work, an applicable sludge ground treatment design procedure is suggested based on parametric analyses; these findings can provide a reference for designing sludge ground treatments in the future. [ABSTRACT FROM AUTHOR]

Published
2023
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70. Cyclic Behavior of Tianjin Soft Clay under Intermittent Combined-Frequency Cyclic Loading

Author

Lei Huayang, Mingjing Jiang, Min Liu, Feng Shuangxi, and Jingjin Liu

Subjects
Materials science, 010102 general mathematics, 0211 other engineering and technologies, Soil Science, 02 engineering and technology, Subgrade, Triaxial shear test, complex mixtures, 01 natural sciences, Soft clay, Cyclic loading, Geotechnical engineering, 0101 mathematics, 021101 geological & geomatics engineering
Abstract

Subgrade soft clays are subjected to intermittent changeable-frequency cyclic loading and exhibit complex dynamic reactions compared with those under single-frequency cyclic loading. This ...

Published
2020

88. Distinct element modeling of rock fragmentation by TBM cutter.

Author

Jiang, Mingjing, Tan, Yafeiou, Zhang, Fuguang, Sun, Ya, and Lei, Huayang

Subjects
CUTTING tools, BORING machinery, DISCRETE element method, FAILURE mode & effects analysis, FAILURE analysis, ROCKS
Abstract

There are many tunneling engineering practices all over the world, in which the tunnel boring machine (TBM) is a main construction way due to its serial advantages such as safety, high efficiency and environment-friendly. TBM cutters are the crucial parts, whose interaction is one of main factors to affect the efficiency of TBM. In this article, a two-dimensional (2D) distinct element method (DEM) code, PFC2D, incorporating an improved microscopic bond contact model proposed for rock, is used to investigate the macro- and micro-mechanical responses during the invasion process of cutter. The influences of the cutter's geometrical parameters, that is, cutter width and cutter angle, and confining pressure, are investigated in study. The DEM results show that: (1) the whole cutter invasion process can be described into three stages: loading stage, unloading stage and residual leaping broken stage; (2) cutter width has more influence on the capability and efficiency of TBM than cutter angle, and both the capability and efficiency of TBM are the best when confining pressure ratio equals to 0.1; (3) consistent with microscopic information, the analyses on specimen failure modes show that cutter with large width and small angle is helpful to rock fragmentation. [ABSTRACT FROM AUTHOR]

Published
2020
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89. Improved air-booster vacuum preloading method for newly dredged fills: Laboratory model study.

Author

Lei, Huayang, Hu, Yao, Zheng, Gang, Liu, Jingjin, Wang, Lei, and Liu, Yingnan

Subjects
*VERTICAL drains, *VACUUM, *SHEAR strength
Abstract

Newly dredged fills feature a high moisture content and a high floating mud content. Based on the conventional vacuum preloading (CVP) method, this article presents a new method of air-booster vacuum preloading (AVP) to reinforce newly dredged fills for different air-booster periods (45, 60 and 90 min). Compared with other methods, this new method features no sand cushion and adopts a self-developed air-booster pipe and a water–air separation device. A series of laboratory model tests were performed to explore the effect of the improved AVP method for the enhancement of newly dredged fills. A comparison of variables monitored during reinforcement (vacuum pressure, surface settlement, water discharge and pore-water pressure) and after reinforcement (water content, vane shear strength, SEM and MIP) indicates that the reinforcement effect of the AVP method is superior to that of the CVP method; the former can effectively alleviate the problem of prefabricated vertical drain (PVD) clogging, greatly reducing engineering costs and significantly shortening construction periods. [ABSTRACT FROM AUTHOR]

Published
2020
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