scholarly journals An Experimental Study of Horizontal Bearing Capacity of Vertical Steel Floral Tube Micropiles with Double Grouting

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Kaiyang Wang ◽  
Yanjun Shang
Keyword(s):  
Bearing Capacity ◽  
Large Scale ◽  
Slip Surface ◽  
Bending Moment ◽  
Shear Capacity ◽  
Soil Reinforcement ◽  
Scale Model ◽  
Soil Pressure ◽  
Floral Tube ◽  
Grouting Pressure

This paper examines the performance of a novel technology, vertical steel floral tube micropiles with double grouting. It is the combination of micropile technology and double grouting technology. A large-scale model tank was applied to impart horizontal bearing capacity, and the slope soil pressure and flexural performance of the micropile were investigated under four experimental conditions. The peak grouting pressure during the double grouting process was defined as the fracturing pressure of the double grouting, and it was positively correlated to the interval time between first grouting and secondary grouting. Compared with traditional grouting, double grouting increased the horizontal bearing capacity of the single micropile with the vertical steel floral tube by 24.42%. The horizontal bearing capacity was also 20.25% higher for the structure with three micropiles, compared with a 3-fold value of horizontal sliding resistance. In the test, the maximum bending moment acting on the pile above the sliding surface was located 2.0–2.5 m away from the pile top, and the largest negative bending moment acting on the pile below the slip surface was located 4.0 m away from the pile top. The ultimate bending moment of the single pile increased by 12.8 kN·m with double grouting, and the bending resistance increased by 96.2%. The experimental results showed that the double grouting technology significantly improved the horizontal bearing capacity of the micropile with the steel floral tube, and the soil reinforcement performance between piles was more pronounced. Also, the shear capacity and the flexural capacity were significantly improved compared with the original technology.

Effect of Existing Building Walls on the Geotechnical Behavior of Foundation under Earthquake Loading

2021 ◽  
Vol 6 (4) ◽  
pp. 100-104
Author(s):  
M. N. Massoud Elsiragy
Keyword(s):  
Large Scale ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Scale Model ◽  
Earthquake Loading ◽  
Three Dimensional Model ◽  
Foundation Soil ◽  
Soil System ◽  
Existing Building ◽  
Building Walls

— Structure’s systems are subjected to additional loads due to earthquakes that may be produces progressive failures. The building illustrates dissimilar categories of failure mechanism for the minor to major earthquake conditions. These structures categorized to the most susceptible type of building has experienced serious hazard or even full failure for the period of seismic activities, therefore their investigation is a complex thing to do. Consequently, this research aims at studying the behaviour of large-scale model of structures constructed with and without brick walls under seismic conditions. The effect of building walls on the performance of the structure during earthquake loading is investigated numerically using PLAXIS 3D software. An eight story building with basement designed on a mat foundation is simulated as three-dimensional model in case of brick walls existing and without brick walls case. The effect of existence such wall building on the stability of foundation soil system is discussed in the form of lateral, horizontal deformation, and foundation acceleration. The studied showed that the reduction of extreme horizontal displacement and bending moment for building foundation with brick walls reached to 43%, and 68% respectively compared to the building without walls. The consideration of wall as filling for super structure significantly reduce the foundation acceleration by as much as 72% of its initial value, which lead to considerable effect of increasing the foundation stability.

Experimental and large-scale field tests of grid-anchor system performance in increasing the ultimate bearing capacity of granular soils

2016 ◽  
Vol 53 (7) ◽  
pp. 1047-1058 ◽  
Author(s):  
M. Mosallanezhad ◽  
N. Hataf ◽  
S.H. Sadat Taghavi
Keyword(s):  
Bearing Capacity ◽  
Large Scale ◽  
Field Tests ◽  
Experimental Tests ◽  
Ultimate Bearing Capacity ◽  
Soil Reinforcement ◽  
Granular Soils ◽  
Anchor System ◽  
Scale Field ◽  
Large Scale Field

Soil reinforcement by means of geogrid is an effective method of increasing the ultimate bearing capacity (UBC) of granular soils. In this study a new system, created by adding cubic anchors to ordinary geogrids, is introduced to increase the UBC of granular soils. This system is called “grid-anchor” (G-A). To analyse the performance of the G-A system in increasing the UBC of granular soils, 45 experimental tests and 9 field tests were performed, the results of which show that the G-A system is 1.8 times more capable than ordinary geogrids in increasing the UBC in square foundations. Furthermore, the failure of soil reinforced by the ordinary geogrid takes place at a settlement of 9% of the foundation width, while the same value for the G-A system is almost 13%.

Volume Displacement Effects on Pile Capacity in Loose Sand

1973 ◽  
Vol 10 (4) ◽  
pp. 645-647
Author(s):  
Eli I. Robinsky ◽  
Christopher B. H. Cragg
Keyword(s):  
Bearing Capacity ◽  
Large Scale ◽  
Loose Sand ◽  
Soil Pressure ◽  
Pile Capacity ◽  
University Of Toronto ◽  
Testing Facility ◽  
Large Scale Testing ◽  
The University ◽  
Displacement Effects

Preliminary tests in the new large-scale testing facility at the University of Toronto reveal that bearing capacity on a pile volume basis is more efficiently developed by a long slender pile or a group of short slender piles than by a pile of larger diameter. The authors attribute this to increased arching in the soil around the pile of greater volume displacement, believing arching buffers the pile from the effects of lateral soil pressure.

Experimental Research on Failure Mode of Micro-Pile in Landslide Reinforcement

2012 ◽  
Vol 226-228 ◽  
pp. 1338-1342
Author(s):  
Shu Feng Wang ◽  
Yong Peng Fu ◽  
Xin Zhao
Keyword(s):  
Failure Mode ◽  
Large Scale ◽  
Load Transfer ◽  
Slip Surface ◽  
Bending Moment ◽  
Pile Group ◽  
Physical Model Test ◽  
Pile Diameter ◽  
Surface Failure ◽  
Numerical Magnitudes

In recent years, micro-pile has been widely applied to landslide treatment engineering due to its advantages in application and construction, and the engineering effect is very evident. Large-scale physical model test was made for studying failure mode of micro-pile group in landslide, which indicated that numerical magnitudes between the displacement and the stress of the piles are better consistent along the load transfer direction. Concentrated destruction points locate on about three times the pile diameter up and down the slip surface. Failure mode of micro-pile in landslide treatment engineering is: pile of the loaded segment usually breaks for bending moment and shear force, and back of sliding side mainly exposes to the tension role, compared to role of tension of anchored segment in front of the micro-piles and compression behind of the piles.

Model Test Study on the Effect of Horizontal Load on the Vertical Bearing Capacity of Disk Pile

2011 ◽  
Vol 368-373 ◽  
pp. 2571-2574
Author(s):  
Cheng Yuan Lu ◽  
Jin Jin Li ◽  
Fan Li Meng
Keyword(s):  
Bearing Capacity ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Initial Time ◽  
Horizontal Load ◽  
Vertical Load ◽  
Soil Pressure ◽  
Test Study ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity

A group of model tests were designed to study the effect of horizontal load on the vertical bearing capacity of disk pile. Three double-disk piles were used in the test, and the distance of the two disks is 5 times as the disk diameter. Drew a horizontal load H=100N/200N/300N on the top of pile1/2/3 respectively, and put on the vertical load stage by stage, then studied the differences of three piles’ bearing properties such as changes of the pile bending moment, the horizontal and vertical deformation on the top, and soil pressure around the pile. Experiment showed that when the horizontal load is quite small, the existence of horizontal load has little to do with vertical bearing capacity. When the load reached a certain level, the p-∆ effect under the vertical load will significantly affect the vertical bearing capacity of the pile. Especially during the initial time while there is a large horizontal displacement or rotation generated by the horizontal load, the pile’s bearing capacity is controlled by the horizontal displacement.

Research on the Bearing Capacity of High-Strength Steel Tubular H-Joints in High-Voltage Transmission Lines

2014 ◽  
Vol 513-517 ◽  
pp. 4123-4126 ◽  
Author(s):  
Yun Xu
Keyword(s):  
Bearing Capacity ◽  
Transmission Lines ◽  
Local Buckling ◽  
Bending Moment ◽  
High Strength ◽  
Steel Tube ◽  
Scale Model ◽  
Tube Plate ◽  
Control Factors ◽  
Local Strength

The steel tube-plate joints are widely applied in tall-slender tower of transmission line engineering,but there are few studies at home and abroad. In this paper,experimental study with full-scale model and analysis based on FEM were carried out on the ultimate bearing capacity of typical h-joints , and the results showed that the bending moment was transferred to the chord from the ear-plate of a narrow area, which led to local buckling on the chord wall , so the local strength of chord is one of the most important control factors in the design of this typical joint;thus the bearing capacity can improve by enhancing the strength of steel or increasing the thickness of ear-plate. In view of the phenomenon that stress concentration is easy to emerge at the intersection of the steel tube-plate joints, some improvement measures for the connections are put forward,such as adding outer half-ring stiffening plates , adding outer-ring plates , adding inner-ring plates, and revising ear-plates to smooth the concave angle , etc.

Experimental investigation of compaction-grouted soil nails

2017 ◽  
Vol 54 (12) ◽  
pp. 1728-1738 ◽  
Author(s):  
Qiong Wang ◽  
Xinyu Ye ◽  
Shanyong Wang ◽  
Scott William Sloan ◽  
Daichao Sheng
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Interface Shear ◽  
Soil Nails ◽  
Soil Nail ◽  
Pull Out ◽  
Grouting Pressure ◽  
Large Scale Model ◽  
Ultimate Failure ◽  
Surrounding Soil

An innovative compaction-grouted soil nail was designed by injecting grout into a special latex balloon (grouting bag) to avoid bleeding and penetration of grout into the surrounding soil. A series of large-scale model tests was performed to study the surrounding soil responses due to grouting and the subsequent pull-out resistance of the soil nail. The experimental results show that grouting pressure plays an important role in the enhancement of the density and (or) strength of the surrounding soil. In addition, during the pull-out process, the compaction-grouted soil nail exhibits a strain-hardening behaviour without a yield point. This is a significant advantage of this new soil nail, indicating that it can enable soil masses to remain stable against a relatively large deformation before ultimate failure. The main factors behind the improvement of the pull-out resistance of the new soil nail are, first, the compaction–densification of the soil near the grouting bag due to grouting, resulting in the enhancement of the shear strength of the soil, and, second, the enlargement of the grouting bag, causing the increase of the interface shear and end resistance to the pull-out of the soil nail.

Analysis of Slope Failure Mechanisms Considering Micropile-Soil Interaction

2013 ◽  
Vol 535-536 ◽  
pp. 565-568 ◽  
Author(s):  
Hong Jian Liao ◽  
Cheng Lin Tian ◽  
Hang Zhou Li
Keyword(s):  
Large Scale ◽  
Slope Failure ◽  
Slip Surface ◽  
Loess Soil ◽  
Scale Model ◽  
Maximum Shear Strain ◽  
Loess Slope ◽  
Slip Surfaces ◽  
Large Scale Model ◽  
Stress And Deformation

A large scale model test was carried out in loess slope, in which the stress and deformation characteristics of slopes reinforced with different arrangements of micropiles were studied. The mechanism of the micropile-soil interaction and the reinforcement effect of micropiles in loess slope were analysed. Based on the scale of in-situ loess slope and the physical mechanics parameters of loess soil, a numerical model was established by using finite difference method. For a reasonable arrangement of micropiles in step-shaped slope, the critical slip surfaces were determined considering the influence of slope inclination, ratio of step height and loading position. The micropiles were arranged in the step-shaped slope based on the critical slip surface, and the relationship between the ultimate bearing capacity of slope and shear strength parameters of loess soil was studied. The maximum shear strain of micropile-soil and moment of micropiles were calculated, and then the mechanism of the micropile-soil interaction was analysed.

scholarly journals Evaluation of Micropiles With Different Configuration Settings for Landslide Stabilization Based on Large-Scale Experimental Testing

2021 ◽  
Vol 9 ◽  
Author(s):  
Xueling Liu ◽  
Jinkai Yan ◽  
Bin Tong ◽  
Lei Liu
Keyword(s):  
Large Scale ◽  
Experimental Testing ◽  
Bending Moment ◽  
Scale Model ◽  
Sliding Surface ◽  
Double Row ◽  
Single Row ◽  
Pile Diameter ◽  
Negative Bending ◽  
Landslide Stabilization

In this study, a large-scale model test was performed to investigate the effect of the single-row and double-row micropiles on the landside stabilization. For two different testing configuration settings, the bending moment along the micropiles, failure mode, and force condition were captured and compared. It is found that the landslide thrust on piles was distributed in a triangular shape. The piles in the front row carried greater pressure than the piles in the rear row. The resistance of the sliding body behind the pile was distributed in a parabolic shape, and mainly concentrated on the middle of the pile. The piles were destroyed due to the combined shearing and bending impact applied near the slipping surface. The boundary of the failure zone was from the position of two times the pile diameter under the slipping surface to the position of two and a half times the pile diameter above the slipping surface. Under the action of the landslide, each row of piles deformed at the same time. The capability of landslide stabilization for double-row piles was better than that of a single-row pile. The sections of the pile above slide surface were mainly subjected to negative bending moments and were distributed mainly within the pile length range of one-third of the anti-sliding section above the sliding surface. The pile body of the embedded section located in the range of ten times the pile diameter below the sliding surface was subjected to a positive bending moment.

scholarly journals Experimental Investigation of Load-Bearing Mechanism of Underwater Mined-Tunnel Lining

2021 ◽  
Vol 9 (6) ◽  
pp. 627
Author(s):  
Zhiqiang Zhang ◽  
Binke Chen ◽  
Qingnan Lan
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Water Pressure ◽  
Tunnel Lining ◽  
Scale Model ◽  
Soil Pressure ◽  
Railway Tunnel ◽  
Load Bearing ◽  
Water Head ◽  
Design Speed

A series of model tests were performed to investigate the load-bearing mechanism of a mined railway tunnel lining under water pressure. To investigate the load-bearing characteristics of different types of linings, a fully closed water pressure exerting device for a noncircular section tunnel was invented. A large-scale model test (1:30) under combined water and soil pressures was conducted to investigate the mechanical characteristics, deformation, stress distribution, crack development process, and failure mode of the underwater mined-tunnel lining. The test results indicated that for the high-speed railway tunnel of Class IV surrounding rock with a design speed of 350 km/h, both the drainage lining and the waterproof lining were controlled by a small eccentric compression under the two test conditions. One had only water pressure, and the other had a variable water pressure and constant soil pressure. The key sections for controlling instability were the bottom of the wall and the inverted arch. The ultimate water head of the drainage lining was 49 m, and the ultimate water head of the waterproof lining was 78 m. In comparison with the drainage lining, the waterproof lining could significantly improve the water-pressure resistance. Thus, design loads of 30 and 60 m are recommended for the drainage and waterproof lining structures, respectively.

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