The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Fan Yu - One of the best experts on this subject based on the ideXlab platform.

  • Degradation process of permafrost underneath Embankments along Qinghai-Tibet Highway: An engineering view
    Cold Regions Science and Technology, 2020
    Co-Authors: Fan Yu, Jilin Qi
    Abstract:

    Abstract Embankment Settlement is closely related to the process of degrading of underling permafrost. Previous studies have focused on the process of permafrost degradation under natural ground surfaces, and the degradation process under roadway Embankments has yet to be investigated. With the influence of climate warming, this study becomes more and more important in the analysis of Embankment Settlement. In this paper, based on the in-situ geothermal data of up to 15 years of 5 typical sections along the Qinghai-Tibet Highway (QTH), the characteristics of permafrost degradation are extensively investigated. According to the characteristics, the trends of thawing and temperature rise in the process of permafrost degradation are analyzed. Corresponding to the tendencies, four stages are defined according to the mean annual ground temperature (MAGT). Combining the features of permafrost degradation in each stage with the in-situ data of Embankment Settlements along QTH, the sources of the Embankment Settlement are identified. The main results are as follows. The permafrost degrades extensively in the five typical sections with different characteristics. With the increase in MAGT, the thawing rate firstly increases and then fluctuates as temperature rise rate increases and then decreases at MAGT of about − 0.5 °C. The four stages are divided: initial degradation stage, for MAGT ≤ − 2.5 °C; the intensive degradation stage, for − 2.5 °C   0 °C. When MAGT is less than about − 1.2 °C, the main contribution of total Settlement is probably thawing Settlement, with the negligible creep of permafrost; when MAGT higher than − 1.2 °C, creep of permafrost starts to have an increasing share in the total Settlement.

  • typical Embankment Settlement heave patterns of the qinghai tibet highway in permafrost regions formation and evolution
    Engineering Geology, 2016
    Co-Authors: Fan Yu, Jilin Qi, Nallathamby Sivasithamparam, Mingyi Zhang, Guilong Wu
    Abstract:

    Abstract The Qinghai–Tibet Highway (QTH) in China has been experiencing a serious Embankment Settlement/heave for more than half a century. The Settlement/heave is resulted from several mechanical processes taking place in different soil layers. In this paper, four typical Settlement/heave patterns of road Embankments in permafrost regions, namely “steady-low rate”, “fluctuate”, “down step” and “steady-high rate” are proposed based on 3-year monitored data of Embankment Settlement/heave and ground temperature at four road sections as well as previous published data of the QTH. Their formation mechanisms and evolution trend in the process of permafrost degradation are discussed from the viewpoints of engineering geology and mechanical process, based on the clarification of the deformation characteristics of different soil layers of a typical road Embankment. The results show that the four patterns are caused by the negligible Settlement/heave, freeze-thaw cycling in an open condition, consolidation of the thawed permafrost layers, and creep of warm permafrost layers respectively. The pattern will change from one to another during the process of permafrost degradation, which will become very complex with the occurrence of frost heave. The results can help revealing the deformation mechanism of road Embankments in permafrost regions, and can benefit road construction and maintenance in the future.

  • Typical Embankment Settlement/heave patterns of the Qinghai–Tibet highway in permafrost regions: Formation and evolution
    Engineering Geology, 2016
    Co-Authors: Fan Yu, Jilin Qi, Nallathamby Sivasithamparam, Mingyi Zhang, Guilong Wu
    Abstract:

    Abstract The Qinghai–Tibet Highway (QTH) in China has been experiencing a serious Embankment Settlement/heave for more than half a century. The Settlement/heave is resulted from several mechanical processes taking place in different soil layers. In this paper, four typical Settlement/heave patterns of road Embankments in permafrost regions, namely “steady-low rate”, “fluctuate”, “down step” and “steady-high rate” are proposed based on 3-year monitored data of Embankment Settlement/heave and ground temperature at four road sections as well as previous published data of the QTH. Their formation mechanisms and evolution trend in the process of permafrost degradation are discussed from the viewpoints of engineering geology and mechanical process, based on the clarification of the deformation characteristics of different soil layers of a typical road Embankment. The results show that the four patterns are caused by the negligible Settlement/heave, freeze-thaw cycling in an open condition, consolidation of the thawed permafrost layers, and creep of warm permafrost layers respectively. The pattern will change from one to another during the process of permafrost degradation, which will become very complex with the occurrence of frost heave. The results can help revealing the deformation mechanism of road Embankments in permafrost regions, and can benefit road construction and maintenance in the future.

  • Analysis on the Settlement of Roadway Embankments in Permafrost Regions
    Journal of Earth Science, 2014
    Co-Authors: Fan Yu, Jilin Qi
    Abstract:

    In permafrost regions, the Embankment Settlement results from several physical and me- chanical processes taking place in the different soil layer, making its mechanism very complicated. Un- der the thermal influence of Embankment, climate warming as well as geothermal source, permafrost may degrade downwards or upwards, which continuously changes the thicknesses of the permafrost layer and the also unfrozen soil layers. Thus, any attempt to analyze the Embankment Settlement seems to be very troublesome and difficult. In this paper, based on ground temperatures of Embankment sec- tions in five typical regions along the Qinghai-Tibet Highway (QTH), the trends of variation of different soil layers and the thermal gradients are investigated. On this basis, four types of sections, which can represent most of the sections of QTH, are deduced to clarify the possible Settlement sources in different soil layers. In order to further confirm and investigate of the Settlement sources, an Embankment model test was carried out. Combing the in-situ monitoring data with the results from the model test, the main Settlement sources in Embankment Settlement are discussed for the four types of sections respectively. The results will facilitate the analysis of Embankment Settlement in permafrost regions.

  • In-situ monitoring of Settlement at different layers under Embankments in permafrost regions on the Qinghai–Tibet Plateau
    Engineering Geology, 2013
    Co-Authors: Fan Yu, Jilin Qi
    Abstract:

    Abstract Ground temperature and Settlement at different soil layers are monitored at four typical sections of the Qinghai–Tibet Highway (QTH) and one section of a newly built test road (NBTR) in Beilu River basin, for the purpose of extensive investigation on the rather complicated mechanism of Embankment Settlement owing to several physical and mechanical processes (i.e., Settlement sources) taking place in different soil layers in permafrost regions. Combining the ground temperature with borehole drilling exploration, thawing temperatures of the permafrost layers in the five sections are determined, and then characteristics of permafrost degradation are analyzed. Three types of sections are summarized to clarify different Settlement sources in different soil layers. On these bases, characteristics of Embankment Settlement under different geological conditions are analyzed; the influence of the seasonal changes of air temperature on Embankment Settlement is discussed; since the two sections, one on QTH and the other on NBTR, are both located in Beilu River basin, they are compared with respect to the variation of the main Settlement source in the process of permafrost degradation. The results help to understand the mechanism of Embankment Settlement.

Jilin Qi - One of the best experts on this subject based on the ideXlab platform.

  • Degradation process of permafrost underneath Embankments along Qinghai-Tibet Highway: An engineering view
    Cold Regions Science and Technology, 2020
    Co-Authors: Fan Yu, Jilin Qi
    Abstract:

    Abstract Embankment Settlement is closely related to the process of degrading of underling permafrost. Previous studies have focused on the process of permafrost degradation under natural ground surfaces, and the degradation process under roadway Embankments has yet to be investigated. With the influence of climate warming, this study becomes more and more important in the analysis of Embankment Settlement. In this paper, based on the in-situ geothermal data of up to 15 years of 5 typical sections along the Qinghai-Tibet Highway (QTH), the characteristics of permafrost degradation are extensively investigated. According to the characteristics, the trends of thawing and temperature rise in the process of permafrost degradation are analyzed. Corresponding to the tendencies, four stages are defined according to the mean annual ground temperature (MAGT). Combining the features of permafrost degradation in each stage with the in-situ data of Embankment Settlements along QTH, the sources of the Embankment Settlement are identified. The main results are as follows. The permafrost degrades extensively in the five typical sections with different characteristics. With the increase in MAGT, the thawing rate firstly increases and then fluctuates as temperature rise rate increases and then decreases at MAGT of about − 0.5 °C. The four stages are divided: initial degradation stage, for MAGT ≤ − 2.5 °C; the intensive degradation stage, for − 2.5 °C   0 °C. When MAGT is less than about − 1.2 °C, the main contribution of total Settlement is probably thawing Settlement, with the negligible creep of permafrost; when MAGT higher than − 1.2 °C, creep of permafrost starts to have an increasing share in the total Settlement.

  • typical Embankment Settlement heave patterns of the qinghai tibet highway in permafrost regions formation and evolution
    Engineering Geology, 2016
    Co-Authors: Fan Yu, Jilin Qi, Nallathamby Sivasithamparam, Mingyi Zhang, Guilong Wu
    Abstract:

    Abstract The Qinghai–Tibet Highway (QTH) in China has been experiencing a serious Embankment Settlement/heave for more than half a century. The Settlement/heave is resulted from several mechanical processes taking place in different soil layers. In this paper, four typical Settlement/heave patterns of road Embankments in permafrost regions, namely “steady-low rate”, “fluctuate”, “down step” and “steady-high rate” are proposed based on 3-year monitored data of Embankment Settlement/heave and ground temperature at four road sections as well as previous published data of the QTH. Their formation mechanisms and evolution trend in the process of permafrost degradation are discussed from the viewpoints of engineering geology and mechanical process, based on the clarification of the deformation characteristics of different soil layers of a typical road Embankment. The results show that the four patterns are caused by the negligible Settlement/heave, freeze-thaw cycling in an open condition, consolidation of the thawed permafrost layers, and creep of warm permafrost layers respectively. The pattern will change from one to another during the process of permafrost degradation, which will become very complex with the occurrence of frost heave. The results can help revealing the deformation mechanism of road Embankments in permafrost regions, and can benefit road construction and maintenance in the future.

  • Typical Embankment Settlement/heave patterns of the Qinghai–Tibet highway in permafrost regions: Formation and evolution
    Engineering Geology, 2016
    Co-Authors: Fan Yu, Jilin Qi, Nallathamby Sivasithamparam, Mingyi Zhang, Guilong Wu
    Abstract:

    Abstract The Qinghai–Tibet Highway (QTH) in China has been experiencing a serious Embankment Settlement/heave for more than half a century. The Settlement/heave is resulted from several mechanical processes taking place in different soil layers. In this paper, four typical Settlement/heave patterns of road Embankments in permafrost regions, namely “steady-low rate”, “fluctuate”, “down step” and “steady-high rate” are proposed based on 3-year monitored data of Embankment Settlement/heave and ground temperature at four road sections as well as previous published data of the QTH. Their formation mechanisms and evolution trend in the process of permafrost degradation are discussed from the viewpoints of engineering geology and mechanical process, based on the clarification of the deformation characteristics of different soil layers of a typical road Embankment. The results show that the four patterns are caused by the negligible Settlement/heave, freeze-thaw cycling in an open condition, consolidation of the thawed permafrost layers, and creep of warm permafrost layers respectively. The pattern will change from one to another during the process of permafrost degradation, which will become very complex with the occurrence of frost heave. The results can help revealing the deformation mechanism of road Embankments in permafrost regions, and can benefit road construction and maintenance in the future.

  • Analysis on the Settlement of Roadway Embankments in Permafrost Regions
    Journal of Earth Science, 2014
    Co-Authors: Fan Yu, Jilin Qi
    Abstract:

    In permafrost regions, the Embankment Settlement results from several physical and me- chanical processes taking place in the different soil layer, making its mechanism very complicated. Un- der the thermal influence of Embankment, climate warming as well as geothermal source, permafrost may degrade downwards or upwards, which continuously changes the thicknesses of the permafrost layer and the also unfrozen soil layers. Thus, any attempt to analyze the Embankment Settlement seems to be very troublesome and difficult. In this paper, based on ground temperatures of Embankment sec- tions in five typical regions along the Qinghai-Tibet Highway (QTH), the trends of variation of different soil layers and the thermal gradients are investigated. On this basis, four types of sections, which can represent most of the sections of QTH, are deduced to clarify the possible Settlement sources in different soil layers. In order to further confirm and investigate of the Settlement sources, an Embankment model test was carried out. Combing the in-situ monitoring data with the results from the model test, the main Settlement sources in Embankment Settlement are discussed for the four types of sections respectively. The results will facilitate the analysis of Embankment Settlement in permafrost regions.

  • In-situ monitoring of Settlement at different layers under Embankments in permafrost regions on the Qinghai–Tibet Plateau
    Engineering Geology, 2013
    Co-Authors: Fan Yu, Jilin Qi
    Abstract:

    Abstract Ground temperature and Settlement at different soil layers are monitored at four typical sections of the Qinghai–Tibet Highway (QTH) and one section of a newly built test road (NBTR) in Beilu River basin, for the purpose of extensive investigation on the rather complicated mechanism of Embankment Settlement owing to several physical and mechanical processes (i.e., Settlement sources) taking place in different soil layers in permafrost regions. Combining the ground temperature with borehole drilling exploration, thawing temperatures of the permafrost layers in the five sections are determined, and then characteristics of permafrost degradation are analyzed. Three types of sections are summarized to clarify different Settlement sources in different soil layers. On these bases, characteristics of Embankment Settlement under different geological conditions are analyzed; the influence of the seasonal changes of air temperature on Embankment Settlement is discussed; since the two sections, one on QTH and the other on NBTR, are both located in Beilu River basin, they are compared with respect to the variation of the main Settlement source in the process of permafrost degradation. The results help to understand the mechanism of Embankment Settlement.

Guilong Wu - One of the best experts on this subject based on the ideXlab platform.

  • typical Embankment Settlement heave patterns of the qinghai tibet highway in permafrost regions formation and evolution
    Engineering Geology, 2016
    Co-Authors: Fan Yu, Jilin Qi, Nallathamby Sivasithamparam, Mingyi Zhang, Guilong Wu
    Abstract:

    Abstract The Qinghai–Tibet Highway (QTH) in China has been experiencing a serious Embankment Settlement/heave for more than half a century. The Settlement/heave is resulted from several mechanical processes taking place in different soil layers. In this paper, four typical Settlement/heave patterns of road Embankments in permafrost regions, namely “steady-low rate”, “fluctuate”, “down step” and “steady-high rate” are proposed based on 3-year monitored data of Embankment Settlement/heave and ground temperature at four road sections as well as previous published data of the QTH. Their formation mechanisms and evolution trend in the process of permafrost degradation are discussed from the viewpoints of engineering geology and mechanical process, based on the clarification of the deformation characteristics of different soil layers of a typical road Embankment. The results show that the four patterns are caused by the negligible Settlement/heave, freeze-thaw cycling in an open condition, consolidation of the thawed permafrost layers, and creep of warm permafrost layers respectively. The pattern will change from one to another during the process of permafrost degradation, which will become very complex with the occurrence of frost heave. The results can help revealing the deformation mechanism of road Embankments in permafrost regions, and can benefit road construction and maintenance in the future.

  • Typical Embankment Settlement/heave patterns of the Qinghai–Tibet highway in permafrost regions: Formation and evolution
    Engineering Geology, 2016
    Co-Authors: Fan Yu, Jilin Qi, Nallathamby Sivasithamparam, Mingyi Zhang, Guilong Wu
    Abstract:

    Abstract The Qinghai–Tibet Highway (QTH) in China has been experiencing a serious Embankment Settlement/heave for more than half a century. The Settlement/heave is resulted from several mechanical processes taking place in different soil layers. In this paper, four typical Settlement/heave patterns of road Embankments in permafrost regions, namely “steady-low rate”, “fluctuate”, “down step” and “steady-high rate” are proposed based on 3-year monitored data of Embankment Settlement/heave and ground temperature at four road sections as well as previous published data of the QTH. Their formation mechanisms and evolution trend in the process of permafrost degradation are discussed from the viewpoints of engineering geology and mechanical process, based on the clarification of the deformation characteristics of different soil layers of a typical road Embankment. The results show that the four patterns are caused by the negligible Settlement/heave, freeze-thaw cycling in an open condition, consolidation of the thawed permafrost layers, and creep of warm permafrost layers respectively. The pattern will change from one to another during the process of permafrost degradation, which will become very complex with the occurrence of frost heave. The results can help revealing the deformation mechanism of road Embankments in permafrost regions, and can benefit road construction and maintenance in the future.

Zhongjie Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Embankment Settlement on Bridge Approach Slab Design: A Few Issues of Concern
    2020
    Co-Authors: George Z. Voyiadjis, Zhongjie Zhang
    Abstract:

    The authors developed in their previous study the design aids for right angle approach slabs under the AASHTO HS20-44 truck load, considering the effect of Embankment Settlement. The present study investigated if these design aids are also valid for the AASHTO LRFD HL93 truck load and for skewed approach slabs. Furthermore, the capacity of the approach slab (designed by using the design aids) was rated in terms of three special truck loads. For these purposes, a 3-D finite element analysis was conducted to model the interaction between the approach slab and the Embankment soils. The predicted internal moments provide design engineers with a scientific basis from which they can properly design the approach slab considering different levels of Embankment Settlements. A proper design of the approach slab will help mitigate the slab rideability (and structural safety) problems. Current AASHTO code specifications do not provide guidelines to design approach slabs that can accommodate a given Embankment Settlement.

  • Design of Ribbed Concrete Approach Slab Based on Interaction with the Embankment
    Transportation Research Record, 2020
    Co-Authors: George Z. Voyiadjis, Zhongjie Zhang
    Abstract:

    To alleviate the "bump" problem at bridge ends, a ribbed concrete approach slab (similar to slab-on-beam bridge decks) was proposed in place of the pile-column-supported approach span or flat slab system. The effect of given Embankment Settlement on the structural performance of a ribbed concrete approach slab with a span length of 60 ft and a width of 40 ft was investigated. The approach slab was modeled as a ribbed slab with a beam spacing of 32, 16, and 12 ft. A three-dimensional finite element analysis was conducted to model the interaction between the approach slab and the Embankment soil. Finite element modeling techniques that simulate the separation of the slab and soil provide information on the effect of the Embankment Settlement on structural performance and beam design. The predicted internal forces provide design engineers with a scientific basis to design the approach slab properly, considering different levels of Embankment Settlements. Current AASHTO code specifications do not provide guid...

  • estimating Embankment Settlement from piezocone penetration test data
    Transportation Research Record, 2011
    Co-Authors: Murad Y Abufarsakh, Xinbao Yu, Rohit Pant, Gavin P Gautreau, Qiming Chen, Zhongjie Zhang
    Abstract:

    The in situ piezocone penetration test (PCPT) has been widely used by the geotechnical engineering community for subsurface soil identification and classification and for the evaluation of many engineering soil properties, such as consolidation parameters. PCPT-derived consolidation properties can be used to estimate the magnitude and time rate of the consolidation Settlement of loaded soils. This paper presents a case study on implementing PCPT technology to evaluate the Embankment Settlement at the Juban Road-I-12 Interchange Bridge in Louisiana. The soil underneath each Embankment site of the bridge was instrumented with a horizontal inclinometer and vertical magnet extensometers. In each Embankment site, PCPT tests were performed, and the soundings of cone tip resistance were used to estimate the constrained modulus (M) profiles. Dissipation tests were conducted at specified penetration depths and used to estimate the vertical coefficient of consolidation (cv). Shelby tube soil samples were collected ...

  • FINITE ELEMENT ANALYSIS OF CONCRETE APPROACH SLAB ON SOIL Embankment
    Geotechnical special publication, 2004
    Co-Authors: George Z. Voyiadjis, Zhongjie Zhang
    Abstract:

    Soil Embankment Settlement causes concrete approach slabs of bridges to lose their contacts and supports from the soil, which results in the deterioration of rideability of the bridge approach slab. To investigate the effect of Embankment Settlements on the performance of the approach slab, a 3-D finite element analysis was conducted in the present study, considering the interaction between the approach slab and the Embankment soil, and consequently the separation of the slab and soil. The predicted internal moments of the approach slab provide design engineers with a scientific basis to properly design the approach slab considering different levels of Embankment Settlements. Current American Association of State Highway Transportation Officials (AASHTO) code specifications do not provide clear guidelines to design approach slabs considering the Embankment Settlements.

Mitsu Okamura - One of the best experts on this subject based on the ideXlab platform.

  • prediction method for liquefaction induced Settlement of Embankment with remedial measure by deep mixing method
    Soils and Foundations, 2004
    Co-Authors: Mitsu Okamura, Keiichi Tamura
    Abstract:

    In order to mitigate liquefaction-induced Embankment Settlement, remedial measures are often implemented for existing Embankments. This paper describes a practical prediction method for Embankment Settlement due to foundation liquefaction, which are remedied with the deep mixing method. Based on a number of centrifuge shaking tests of Embankment, an empirical relation between crest Settlement and displacement of the remedied zone is established. Then, a calculation method for displacement of the remedied zone is developed. In the method, a macroscopic failure envelope and a plastic displacement potential in the general load space are considered to evaluate the subgrade reaction forces on the base of the remedied zone. The method is capable of calculating not only horizontal, vertical or rotational displacement alone, but their combined effect. The method is validated through comparisons of calculated results with centrifuge test observations. The calculated displacement components compare quite well with those measured. This method can be a useful tool for design of countermeasures based on a specified limit Settlement.

  • effects of remedial measures for mitigating Embankment Settlement due to foundation liquefaction
    International Journal of Physical Modelling in Geotechnics, 2002
    Co-Authors: Mitsu Okamura, Osamu Matsuo
    Abstract:

    In Japan, after the Hyogoken-nambu earthquake remedial measures have often been constructed for river dikes supported on liquefiable sand beds. In this study a series of dynamic centrifuge tests wa...