scholarly journals Experiment Investigation on Stress Characteristics of Grouting Microsteel Pipe Piles with Cement-Soil Wall

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Shujuan Yang ◽  
Mingyi Zhang ◽  
Xiaoyu Bai ◽  
Xueying Liu ◽  
Chen Zheng
Keyword(s):  
Bearing Capacity ◽  
Stress Measurement ◽  
Flexural Rigidity ◽  
Bending Moment ◽  
Steel Tube ◽  
Rock Foundation ◽  
Foundation Pit ◽  
Anchor System ◽  
In Situ Stress Measurement ◽  
Cement Soil

Microsteel pipe piles are widely used in excavation support owing to their excellent bearing capacity, flexural rigidity, construction speed, and adaptability. In this study based on a project in soil-rock layers in Qingdao, China, a new type of support combining microsteel pipe piles mounted in cement-soil piles and anchors was adopted and studied. The inner force change laws and bearing capacity of microsteel pipe piles were discussed through in situ stress measurement and laboratory antibending tests on three microsteel pipe piles. It was found that the bending moment of the piles gradually increased with the foundation excavation and maximized at the pile head. The bending moment was larger at the upper and smaller at the lower part along the depth direction, indicating it is reasonable to design and calculate microsteel pipe piles by the pile-anchor system. The variation law of the foundation pit displacement with the excavation depth was monitored. The horizontal displacement of the foundation pit is the maximum at the base top, which is 6.5 mm. The flexural strength of the miniature steel tube pile after grouting is 40% higher than that of the miniature steel tube pile without grouting. It was indicated that the grouting microsteel pipe piles could be implanted in cement-soil piles, which improved the flexural rigidity of cement-soil piles and limited the deformation of foundation pits. This study provides reference for the design and construction of soil-rock foundation pit supporting projects. At the same time, it provides reference for the application of miniature steel pipe piles in other fields.

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.

Buckling Analysis Method and Application of a Square Steel Tube Member with Initial Geometric Imperfection under Axial Compressive Load and Bending Moment

2013 ◽  
Vol 351-352 ◽  
pp. 237-240 ◽  
Author(s):  
Peng Niu ◽  
Xiao Chu Wang ◽  
Chun Fu Jin ◽  
Yong Qi Zhang
Keyword(s):  
Finite Element Method ◽  
Bearing Capacity ◽  
Compressive Load ◽  
Bending Moment ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Geometric Imperfection ◽  
Axial Compressive Load ◽  
Initial Geometric Imperfection ◽  
Square Steel Tube

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for a square steel tube member are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact by initial geometric imperfections on the square steel tube member under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. The results of the example show that the presence of initial imperfections reduces the ultimate bearing capacity of the steel member to a great extent. It is also found that the influence of the initial geometric imperfection on the ultimate bearing capacity of member is smaller when the M increases.

Model Test Research on Horizontal Bearing Characteristics of Close-Ended Valibale Section Pipe Pile

2014 ◽  
Vol 638-640 ◽  
pp. 475-479
Author(s):  
Qing Guang Yang ◽  
Yi Han Chen ◽  
Jie Tian ◽  
Jie Liu
Keyword(s):  
Bearing Capacity ◽  
Load Transfer ◽  
Small Diameter ◽  
Bending Moment ◽  
Horizontal Load ◽  
Foundation Pit ◽  
Pipe Pile ◽  
Diameter Pipe ◽  
Load Displacement ◽  
Constant Section

Base on indoor model tests of three variable section pipe piles and two constant section pipe piles performed in foundation pit,the load transfer mechanism of two kinds of close-ended pipe piles are studied by comparing horizontal load-displacement curves, critical load and bending moment of piles. Results show that horizontal load-displacement curves change slowly and horizontal bearing capacity of valiable section pipe piles will be higher than constant section pipe piles with equal average diameters.Comparing with constant section pipe piles 1# and 2# with equal average diameters, unit volume horizontal critical bearing capacity of 3# and 4# are improved 8.7% and 34.2% respectively and which have different degrees of increse with improvement of valiable section ratio. Moreover,there are two maximum bending moment to valialble section pipe piles insteard of one to constant section pipe piles.To pipe piles 3#,4# and 5#, maximum bending moment ratio of big diameter pipe to small diameter pipe of valiable section pipe pile are 3.13、2.33 and 1.89 respectively. To pipe piles 3# and 4#, maximum bending moments of big diameter pipe are improved 26.8% and 28.4%.Howeverm,maximum bending moment of small diameter pipe are improved 54.1% and 111.8%.So,it is very clear that valiable section pipe pile is more reasonable than constant section pipe pile in bearing characteristics.

Theory Analysis on Buckling of a Square Steel Tube Member Strengthened by CFRP with the Initial Imperfection

2013 ◽  
Vol 351-352 ◽  
pp. 241-245
Author(s):  
Chun Fu Jin ◽  
Peng Niu ◽  
Yong Sheng Zhao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Carbon Fibre ◽  
Bearing Capacity ◽  
Compressive Load ◽  
Bending Moment ◽  
Steel Tube ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection ◽  
Square Steel Tube

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, considering the initial geometric imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for a square steel tube member with flange outsides wrapped by carbon fibre are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact of the initial geometric imperfection on the square steel tube steel member wrapped by carbon fibre under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. Compared the reinforced effect of the carbon fibrer to the perfection member with the defect member, we find that the former is higher than the latter. The results of the example also show that the presence of initial geometric imperfection reduces the ultimate bearing capacity of the steel member to a great extent. The influence of defect member gradually decreases when the given moment rises.

Study on Buckling of Two Kinds of Thin-Walled Steel Members with Imperfection

2015 ◽  
Vol 744-746 ◽  
pp. 309-314
Author(s):  
Peng Niu ◽  
Hai Tao Wang ◽  
Chun Fu Jin ◽  
Ying Guo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Bearing Capacity ◽  
Compressive Load ◽  
Bending Moment ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Axial Compressive Load ◽  
Steel Members ◽  
Square Steel Tube

Based on Ježek method of computing the elastic-plastic buckling of the members under the axial compressive load and the bending moment, considering the initial imperfection, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the maximum moment of inertia for an H-shaped member and a square steel tube member are derived. Using the elastic-plastic finite element method and the theory of nonlinear buckling, the impact by initial geometric imperfections on the H-shaped steel member and the square steel tube member under the axial compressive load and the bending moment are analyzed and the numerical solutions of ultimate bearing capacity are obtained. By compared with the values of the finite element method (FEM), it shows that the analytical method in this paper is valid. The results of the example show that the presence of initial imperfections reduces the ultimate bearing capacity of the two kinds of steel members to a great extent. It is also found that the influence of the initial geometric imperfection on the ultimate bearing capacity of members is smaller when the bending moment increases.

Node Additional Bending Moment's Influence on Plane K Shape Steel Tube Tubular Joint Ultimate Bearing Capacity

2014 ◽  
Vol 578-579 ◽  
pp. 732-735
Author(s):  
Xian Liao ◽  
Jun Yong ◽  
Zhong Qing Wang
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Plastic Material ◽  
Bending Moment ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Structure Design ◽  
Plastic Shell ◽  
Elastic Plastic ◽  
Tubular Joint

The study of the existing data and steel structure design specification on node ultimate bearing capacity is limited to simply analyze its axial bearing capacity, but the study on the ultimate bearing capacity of the additional bending moment with nodes is very deficient. This article first briefly analyzed the size of the steel tube 's influence on the node additional bending moment from the aspects of node rigidity, and showed that basis and necessity of considering node additional bending moment in steel tube structure ,and then used three-dimensional four nodes elastic-plastic shell unit shell 181 and ideal elastic-plastic material to establish finite element model of K shape round steel tube tubular joint in the ANSYS finite element program, under the consideration of the geometric nonlinearity and material nonlinearity, respectively got the ultimate bearing capacity of K shape round steel tube tubular joint under the action of additional bending moment of different nodes ,analyzed the changes of mechanical property of the nodes after bearing of the additional bending moment, and showed that additional bending moment's influence rule on K shape round steel tube tubular joint ultimate bearing capacity.

scholarly journals Experimental Study of an Inflatable Recyclable Anchor

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Taoli Xiao ◽  
Yunlong He
Keyword(s):  
Bearing Capacity ◽  
Embedment Depth ◽  
The Novel ◽  
Low Carbon ◽  
Pullout Capacity ◽  
Force Transmission ◽  
Inflation Pressure ◽  
Foundation Pit ◽  
Anchor System ◽  
Repeated Use

This paper describes an investigation into the performance and pullout capacity of a new inflatable anchor system embedded in deep excavation engineering. The proposed inflatable recyclable anchor system consists of a rubber pneumatic bag, movable steel plate, and force transmission bar, which can all be recycled after use. By conducting a number of field pullout tests, it is found that the pullout bearing capacity of the proposed anchor is related to the inflation pressure, the length of the rubber pneumatic bag, and the embedment depth. It is found that, with the exponential increase of inflation pressure or length of the rubber pneumatic bag, the pullout bearing capacity of the novel inflatable anchor increases exponentially. The proposed inflatable recyclable anchor can meet the bearing requirements of traditional grouted anchors. Moreover, the proposed anchor not only has better supporting effects than traditional grouted ones, but it also has the advantages of recyclability, repeated use, and rapid formation of anchorage force. It is a new green and low-carbon anchorage, so it will have good application prospects in temporary foundation pit slope engineering.

scholarly journals Behavior Characteristics of Single Batter Pile under Vertical Load

2021 ◽  
Vol 11 (10) ◽  
pp. 4432
Author(s):  
Jiseong Kim ◽  
Seong-Kyu Yun ◽  
Minsu Kang ◽  
Gichun Kang
Keyword(s):  
Bearing Capacity ◽  
Relative Density ◽  
Model Test ◽  
Ground Surface ◽  
Bending Moment ◽  
Vertical Position ◽  
Vertical Load ◽  
Behavior Characteristics

The purpose of this study is to grasp the behavior characteristics of a single batter pile under vertical load by performing a model test. The changes in the resistance of the pile, the bending moment, etc. by the slope of the pile and the relative density of the ground were analyzed. According to the results of the test, when the relative density of the ground was medium and high, the bearing capacity kept increasing when the angle of the pile moved from a vertical position to 20°, and then decreased gradually after 20°. The bending moment of the pile increased as the relative density of the ground and the batter angle of the pile increased. The position of the maximum bending moment came closer to the ground surface as the batter angle of the pile further increased, and it occurred at a point of 5.2~6.7 times the diameter of the pile from the ground surface.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

In Situ Stress Measurement and Inversion in Deep Roadway

2013 ◽  
Vol 734-737 ◽  
pp. 759-763 ◽  
Author(s):  
Yong Li ◽  
Yun Yi Zhang ◽  
Ren Jie Gao ◽  
Shuai Tao Xie
Keyword(s):  
Field Measurement ◽  
Stress Measurement ◽  
Measurement Data ◽  
Back Analysis ◽  
In Situ Stress ◽  
Deep Mine ◽  
Accuracy Requirement ◽  
Initial Stress Field ◽  
In Situ Stress Measurement

Jixi mine area is one of the early mined areas in China and it's a typical deep mine. Because of large deformation of underground roadway and dynamic disasters occurred frequently in this mine, five measurement points of in-situ stress in this mine was measured and then analyzed with inversion. Based on these in-situ stress measurement data, numerical model of 3D in-situ stress back analysis was established. According to different stress fields, related analytical samples of neural network were given with FLAC program. Through the determination of hidden layers, hidden nodes and the setting of parameters, the network was optimized and trained. Then according to field measurement of in-situ stress, back analysis of initial stress field was conducted. Compared with field measurement, with accuracy requirement satisfied, it shows that the in-situ stress of rock mass obtained is basically reasonable. Meanwhile, it proves that the measurement of in-situ stress can provide deep mines with effective and rapid means, and also provide reliable data to optimization of deep roadway layout and supporting design.

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