Bearing Behavior of Steel Foot Pipe in Tunnel on Soft Base

2010 ◽  
Vol 163-167 ◽  
pp. 3604-3609
Author(s):  
Yi Min Wu
Keyword(s):  
Numerical Simulations ◽  
Bearing Capacity ◽  
Influencing Factors ◽  
Surrounding Rock ◽  
Steel Pipe ◽  
Geological Condition ◽  
Lateral Zone ◽  
Maximal Stress ◽  
Dip Angle ◽  
Bearing Behavior

Numerical simulations were conducted to investigate the bearing behaviour of steel foot pipe. Main mechanical affections occur at the lateral zone, and the maximal stress occurs at the lateral end of the pipe. With the increase of cross direction load, the maximal stress increases and exceeds the strength of material, and the pipe is pulled out. The influencing factors of bearing capacity of the steel foot pipe were studied. Some important results different from engineering experiences are as following: 1) to steel foot pipe that can not penetrate the soft base, its reasonable dip angle is very small for its low longitudinal bearing capacity; 2) steel pipe with diameter of 42mm is unsuitable for foot steel pipe because its low cross bearing capacity; 3) to a given geological condition and pipe parameter, the reasonable length of steel pipe is certain, extra longer pipes can’t obtain larger capacity; 4) surrounding rock near the support structure should be especially reinforced by drilling grouting holes along the whole steel pipe.

Strength Assessments of Concrete-Filled Steel Tubular Support of Soft Rock Roadway

2013 ◽  
Vol 838-841 ◽  
pp. 1884-1890 ◽  
Author(s):  
Guang Long Qu ◽  
Yan Fa Gao ◽  
Liu Yang ◽  
Bin Jing Xu ◽  
Guo Lei Liu ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Coal Mine ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Flexural Performance ◽  
Laboratory Test Results ◽  
Different Types ◽  
Soft Rock Roadway ◽  
Core Concrete ◽  
Rock Roadway

Compared with I-shaped and U-shaped supports in soft rock roadway, concrete-filled steel tubular (CFST) support, as a new supporting form, has stronger bearing capacity with reasonable price. So it is becoming more and more popular in roadway supporting of coal mine in China. In this article, the surrounding rock in soft rock roadway was classified into three different types: hard rock in deep coal mine, soft surrounding rock, extremely soft surrounding rock. And, according to the characteristics of deformation failure of the CFST support and the surrounding rock in the industrial tests, three different strength assessments, including assessment of axial compressive strength, assessment of lateral flexural performance, assessment of hardening rate of core concrete, were proposed through mechanical analysis and laboratory tests for the three different types of the surrounding rock, respectively. Moreover, aimed to insufficient flexural strength of the support or low hardening rate of the core concrete in some of the roadway supporting, strengthening lateral flexural performance or making early strength concrete was necessary for the above unfavorable situations. The laboratory test results showed that the ultimate bearing capacity for the CFST support with φ194*8mm of steel tube reinforced by φ38mm round steel was 31% greater than that of the unreinforced one, 177% greater than that of the U-shaped one with equivalent weight per unit length.

scholarly journals Study on Stability and Plastic Zone Distribution of Tunnel with Thin Carbonaceous Slate at Different Dip Angles

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jin Zhang ◽  
Chuanhao Xi ◽  
Qian Zhang ◽  
Mengxue Wang
Keyword(s):  
Tensile Strength ◽  
Plastic Zone ◽  
Field Measurement ◽  
Joint Angle ◽  
Rock Joint ◽  
Great Influence ◽  
Surrounding Rock ◽  
Test Field ◽  
Maximum Displacement ◽  
Dip Angle

Carbonaceous slate is heterogeneous and anisotropic, which has a great influence on the stability of tunnel. In this paper, by means of laboratory test, field measurement, and numerical simulation, the surrounding rock stability and plastic zone distribution characteristics of the carbonaceous slate tunnel at different intersection angles are analyzed. First, combined with the Haibaluo tunnel project, Brazilian splitting and uniaxial compression tests of jointed carbonaceous slate are performed. The test results show that the tensile strength of carbonaceous slate is related to joint dip angle. When the joint angle is 0°, the tensile strength is the largest and decreases with the increase of the joint angle. The uniaxial strength of rock decreases first and then increases. Based on the discrete fracture network (DFN) technology, a calculation model is established. The calculation results show that the maximum displacement is 0.45 m, when the dip angle of the surrounding rock joint is 45°. The field measurement also shows that the dip angle of the surrounding rock joint has an important influence on the distribution of the plastic zone. When the joint dip angle is 45°, the plastic zone develops most strongly.

Numerical Analysis for Bolt Length Based on the Stress Response of Anchorage Surrounding Rock

2012 ◽  
Vol 204-208 ◽  
pp. 4481-4485
Author(s):  
Bin Wang ◽  
Fu Jun Zhao ◽  
Wen Bin Peng
Keyword(s):  
Numerical Simulation ◽  
Stress Response ◽  
Numerical Analysis ◽  
Bearing Capacity ◽  
Distribution Curve ◽  
Surrounding Rock ◽  
Effective Length ◽  
Plastic Failure ◽  
Deep Rock ◽  
Peak Value

The current researches on bolt length are rarely concerned with self-bearing characteristics of anchorage surrounding rock，its stress response is seldom used to analyze the bolt effective length. Tangential stress σθ of surrounding rock is sensitive to mechanical variation of surrounding rock plastic failure fields. When surrounding rock bolted, the distribution curve of σθ presents internal and external peak values from the surface rock to the deep rock, which is verified by numerical simulation. Internal peak value of σθ curve increases with the bolt length, which means the bearing capacity of surrounding rock in plastic failure division is improved, correspondingly, external peak value decreases which shows the supporting behavior of the deep rock is weakened. The results of numerical simulations prove that there exists an effective value of bolt length. If bolt length beyond it, the bearing capacity of anchorage surrounding rock cannot be improved obviously.

Investigation of the Factors Influencing the Flowback Ratio in Shale Gas Reservoirs: A Study Based on Experimental Observations and Numerical Simulations

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Lin Hun ◽  
Zhou Xiang ◽  
Chen Yulong ◽  
Yang Bing ◽  
Song Xixiang ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Capillary Pressure ◽  
Influencing Factors ◽  
Shale Gas ◽  
Water Distribution ◽  
Pressure Curve ◽  
Gas Reservoirs ◽  
Desorption Process ◽  
Fluid Saturation ◽  
Shale Gas Reservoirs

Abstract The flowback behavior of hydraulic fractured horizontal well in shale gas reservoir is relatively different from that of conventional reservoirs. Therefore, it is necessary to investigate the relationship between the potential influencing factors and the flowback behavior in shale gas reservoirs. This study is based on experimental observations and numerical simulations. In the experiments, the flowback process was simulated through a gas displacement experiment, and the cores were scanned simultaneously to obtain the water distribution. Then, the water migration and retention mechanisms were investigated to determine the flowback behavior. For the numerical simulations, a multi-porosity model was established. The mathematical model accounted for the capillary pressure term. By matching the fluid saturation-front curves of the experimental and simulation results, a fitted capillary pressure curve, which reflects the multiple mechanisms controlling flowback, was obtained. Based on the established model and fitted capillary pressure, the flowback behavior and relevant influencing factors of the shale gas were investigated. The results show that the flowback ratio is inversely proportional to the clay content of the shale. A high salinity fracturing fluid or a surfactant solution can increase the flowback ratio. In addition, the injection pressure is proportional to the flowback ratio, while the matrix permeability and the flowback ratio have an inverse relationship. The adsorption–desorption process of gas has no significant effect on the flowback ratio. This study aims to provide a new method for analyzing the flowback performance of shale gas using a combination of experimental and numerical simulation methods.

scholarly journals Research on Uplift Bearing Performance of Assembled Steel Pipe Pile used in Transmission Lines in Mountainous Terrain

2019 ◽  
Vol 275 ◽  
pp. 03008
Author(s):  
Kun Zhou ◽  
Linhua Chen ◽  
Xiangyu Gu ◽  
Qi Zhang
Keyword(s):  
Bearing Capacity ◽  
Transmission Lines ◽  
Frictional Resistance ◽  
Steel Pipe ◽  
Mountainous Terrain ◽  
Pipe Pile ◽  
Fbg Sensors ◽  
Strength And Stiffness ◽  
Steel Pipe Pile ◽  
Lateral Friction

Assembled steel pipe pile, which is a novel pile foundation, is developed in the paper. The ultimate uplift bearing capacity of the pile is proposed, and simulation by Plaxis3D and the corresponding experiment are performed to verify the theory. In the simulation, ultimate uplift bearing capacity of the assembled steel pipe pile and ultimate lateral frictional resistance of the interface of pile-soil increases with the increasing of the strength and stiffness of the interface of pile-soil, and with the increasing of length-diameter ratio, ultimate uplift bearing capacity of the assembled steel pipe pile increases while the ultimate lateral frictional resistance decreases gradually. The ultimate lateral friction is influenced by both of the strength of the soil around the pile and the interface of pile-soil, and the ultimate uplift bearing capacity obtained by simulation and theoretical calculation are close. Long-gauge FBG sensors are used in the experiment for measuring the longitudinal strain of the pile, and the error of ultimate uplift bearing capacity between the results of experiment and theory is less than 10%.

scholarly journals Key Parameters of Roof Cutting of Gob-Side Entry Retaining in a Deep Inclined Thick Coal Seam with Hard Roof

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 934 ◽  
Author(s):  
Jinzhu Hu ◽  
Manchao He ◽  
Jiong Wang ◽  
Zimin Ma ◽  
Yajun Wang ◽  
...  
Keyword(s):  
Numerical Model ◽  
Coal Seam ◽  
Economic Benefits ◽  
Surrounding Rock ◽  
Thick Coal Seam ◽  
Hard Roof ◽  
Coal Recovery ◽  
Rock Structure ◽  
Different Depths ◽  
Dip Angle

Gob-side entry retaining by roof cutting (GERRC) employed in a deep inclined thick coal seam (DITCS) can not only increase economic benefits and coal recovery, but also optimize surrounding rock structure. In accordance with the principles of GERRC, the technology of GERRC in DITCS is introduced and a roof-cutting mechanical model of GERRC is proposed to determine the key parameters of the depth and angle of RC. The results show that the greater the RC angle, the easier the caving of the goaf roof, but the length of cantilever beam increases. The depth of RC should account for the dip angle of the coal seam when the angle is above 20°. Increasing the coal seam dip angle could reduce the volume of rock falling of the goaf roof, but increase the filling height of the upper gangue to slide down. According to numerical model analysis of the stress and displacement of surrounding rock at different depths and angles of RC, when the depth of RC increased from 9 m to 13 m, the distance between the stress concentration zone and the coal side is increased. When the angle of RC increased from 0° to 20°, the value of roof separation is decreased. GERRC was applied in a DITCS with 11 m depth and 20° RC angle, and the field-measured data verified the conclusions of the numerical model.

Experimental and numerical investigation on the vertical bearing behavior of discrete connected new-type precast reinforced concrete floor system

2020 ◽  
Vol 23 (11) ◽  
pp. 2276-2291
Author(s):  
Rui Pang ◽  
Yibo Zhang ◽  
Longji Dang ◽  
Lanbo Zhang ◽  
Shuting Liang
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cover Plate ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Concrete Floor ◽  
New Type ◽  
Vertical Bearing ◽  
Floor System ◽  
Bearing Behavior

This article proposes a new type of discrete connected precast reinforced concrete diaphragm floor system that consists of precast flat slabs and slab joint connectors. An experimental investigation of discrete connected new-type precast reinforced concrete diaphragm under a vertical distributed static load was conducted, and the effect of slab joint connectors on the load-bearing capacity was evaluated. Then, a finite element analysis of discrete connected new-type precast reinforced concrete diaphragm, precast reinforced concrete floors without slab connectors, and cast-in-situ reinforced concrete floor were performed to understand their working mechanism and determine the differences in load-bearing behavior. The results indicate that the load-bearing capacity and stiffness of discrete connected new-type precast reinforced concrete diaphragm increase considerably as the hairpin and cover plate hybrid slab joint connectors can efficiently connect adjacent precast slabs and enable them to work together under a vertical load by transmitting the shear and moment forces in the orthogonal slab laying direction. The deflection of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction is mainly caused by the opening deformation of the slab joint and the rotational deformation of the precast slabs. This flexural deformation feature can provide reference for establishing the bending stiffness analytical model of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction, which is vitally important for foundation of the vertical bearing capacity and deformation calculation method. The deflection and crack distribution patterns infer that the discrete connected new-type precast reinforced concrete diaphragm processes the deformation characteristic of two-way slab floor, which can provide a basis for the theoretical analysis of discrete connected new-type precast reinforced concrete diaphragm.

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