Study on Influence of Soil Hardness Change on Pile Bearing Capacity and Settlement in Single Bearing Layer of Pile End

Although compacted soil can be recovered through root development of planted seedlings, the relationship between root morphologies and soil physical properties remain unclear. We investigated the impacts of soil compaction on planted hybrid larch F1 (Larix gmelinii var. japonica×L. kaempferi, hereafter F1) seedlings with/without N loading. We assumed that N loading might increase the fine root proportion of F1 seedlings under soil compaction, resulting in less effects of root development on soil recovery. We established experimental site with different levels of soil compaction and N loading, where two-year-old F1 seedlings were planted. We used a hardness change index (HCI) to quantify a degree of soil hardness change at each depth. We evaluated root morphological responses to soil compaction and N loading, focusing on ectomycorrhizal symbiosis. High soil hardness reduced the total dry mass of F1 seedlings by more than 30%. Significant positive correlations were found between HCI and root proportion, which indicated that F1 seedling could enhance soil recovery via root development. The reduction of fine root density and its proportion due to soil compaction was observed, while these responses were contrasting under N loading. Nevertheless, the relationships between HCI and root proportion were not changed by N loading. The relative abundance of the larch-specific ectomycorrhizal fungi under soil compaction was increased by N loading. We concluded that the root development of F1 seedling accelerates soil recovery, where N loading could induce root morphological changes under soil compaction, resulting in the persistent relationship between root development and soil recovery.

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STUDY ON CHARACTERISTICS OF PILE END BEARING CAPACITY ON THIN BEARING LAYER(PART 1): INVESTIGATION ON FACTORS WHICH INFLUENCE BEARING CAPACITY CHARACTERISTICS BY MODEL PILE TEST

Journal of Structural and Construction Engineering (Transactions of AIJ) ◽

10.3130/aijs.85.1035 ◽

2020 ◽

Vol 85 (774) ◽

pp. 1035-1044

Author(s):

Masahiro YAMAZAKI

Keyword(s):

Bearing Capacity ◽

Pile Test ◽

End Bearing Capacity ◽

Model Pile ◽

Bearing Layer

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SOIL STRUCTURE AND HARDNESS CHANGE RESULTING FROM THE DEPTH OF A TRACTOR TRACK UNDER DIFFERENT WHEEL DRIVE TOWING STRENGTH

Bulletin Samara State Agricultural Academy ◽

10.12737/article_5c8761434ab4c1.18986391 ◽

2019 ◽

pp. 22-27

Author(s):

Олег Черников ◽

Oleg Chernikov ◽

Александр Быченин ◽

Aleksandr Bychenin ◽

Дмитрий Сазонов ◽

...

Keyword(s):

Soil Fertility ◽

Sharp Increase ◽

Soil Structure ◽

Layer Depth ◽

Structural Composition ◽

Soil Hardness ◽

Wheel Drive ◽

Hardness Change ◽

The Impact

The aim of the research is to reduce the influence of wheel propellers on the structure and hardness of the soil in the track of the tractor. The technique and results of the study of the impact of the drive wheels of the power tool of the machine-tractor unit (MTA) on the structure and hardness of the soil in the layers of the horizon are presented. The influence of slipping on these indicators is revealed. The research has been of MTA consisting of a tractor of drawbar category 0,6 kN (T-25A) and trailed cultivator KPS-4,0. The method of investigation involved the determination of changes in the structural composition of the soil (DS parameter,%) by the number of erosion-hazardous (less than 0.25 mm in size) particles, as well as soil hardness (DN parameter, kg/cm2) on the track of the tractor in different layers of the horizon (0...50 mm; 50...100 mm; 100...150 mm; 150...200 mm and 200...250 mm). The slipping mode was changed by changing the number of working sections of the cultivator. The slipping of the driving wheels was taken into account, as well as the agronomic background. The studies were carried out in conditions of equal humidity. The speed of MTA, its weight and the air pressure in the tires of the drive wheels is maintained constant. It is established that the greatest change in the structure of the soil on the layers of the horizon is exposed when slipping δ=20...30%. To change the hardness of this range is also the least favorable. The obtained dependences of the structure and hardness of the soil on the layers of the horizon from slipping allow us to recognize the rational modes of MTA work, in which the slipping of the propelling power means is in the range of 9 to 12% regardless of from the soil fertility. Slipping over 12% leads to a sharp increase in the soil structure of the number of erosion-hazardous particles, as well as an increase in the hardness of the soil in the track of the tractor in 3,4 ... 3,7 times in the layer depth of 50 ... 100 mm.

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STUDY ON CHARACTERISTICS OF PILE END BEARING CAPACITY ON THIN BEARING LAYER (PART 2): INVESTIGATION ON BEARING CAPACITY MECHANISM BY MODEL PILE TEST

Journal of Structural and Construction Engineering (Transactions of AIJ) ◽

10.3130/aijs.86.77 ◽

2021 ◽

Vol 86 (779) ◽

pp. 77-87

Author(s):

Masahiro YAMAZAKI

Keyword(s):

Bearing Capacity ◽

Pile Test ◽

End Bearing Capacity ◽

Model Pile ◽

Bearing Capacity Mechanism ◽

Bearing Layer

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The influence of the stratum structure of the pipe pile sliding pile of the offshore platform

Global Journal of Engineering and Technology ◽

10.28933/gjmse-2021-02-1805 ◽

2021 ◽

pp. 6

Author(s):

Keyword(s):

Bearing Capacity ◽

Pile Foundation ◽

Soft Soil ◽

Limit State ◽

Soil Layer ◽

Measurement Data ◽

Friction Resistance ◽

Side Friction ◽

The Impact ◽

Bearing Layer

This article has carried on the theoretical analysis to the generation mechanism of the sliding pile phenomenon. A certain prediction was made on the causes of slipping piles and their influencing factors. At the same time, it is based on the collected field measurement data, an engineering example is selected to briefly analyze the changes in the bearing capacity of the pile foundation after the sliding pile occurs. It is found that the influence of the sliding pile on the bearing capacity of the pile foundation is mainly the influence on the side friction resistance of the pile, and the reduction of the soil resistance is also mainly due to the reduction of the side friction resistance of the pile. Finally, using ABAQUS finite element analysis software, a numerical simulation analysis was carried out on the changes of the stratum structure, the analysis results show that the position change of the soft soil layer has a certain influence on the bearing capacity of the pile, but it does not change the settlement of the pile top under the limit state; The greater the strength of the supporting layer, the greater the bearing capacity and the greater the displacement when reaching the limit state; The length of the slipped pile does not affect the bearing capacity of the pile foundation, and the farther the slipping occurs from the bearing layer, the smaller the impact on the bearing capacity of the pile foundation. Therefore, in the actual project, attention should be paid to the selection of the bearing layer and the soft soil layer close to the bearing layer should be removed to reduce the impact of the slipping pile on the bearing capacity of the pile foundation and ensure that the bearing capacity of the pile foundation meets the design requirements.

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