Numerical modeling of progressive failure of rigid piles under embankment load

2019 ◽  
Vol 56 (1) ◽  
pp. 23-34 ◽  
Author(s):  
Gang Zheng ◽  
Xinyu Yang ◽  
Haizuo Zhou ◽  
Jinchun Chai
Keyword(s):  
Tensile Stress ◽  
Failure Mode ◽  
Shear Failure ◽  
Slip Surface ◽  
Progressive Failure ◽  
Soft Clay ◽  
Bending Moment ◽  
Tensile Failure ◽  
Failure Behavior ◽  
Embankment Load

Rigid piles (e.g., concrete piles) have been widely used to improve soft clay for the rapid construction of embankments. In this study, a damage plasticity model that considers the brittle failure behavior of concrete and the frictional properties along cracks is proposed to study the progressive failure of rigid piles under an embankment load. The mechanical characteristics of piles in different locations have been analyzed. The results show that the essential failure mode for rigid piles is tensile failure, which is primarily governed by the distribution of the bending moment and the axial force within the piles. Pile rupture releases stress and causes a significant increase in the tensile stress within neighboring piles, possibly leading to the progressive failure of adjacent piles. Failure in the upper section of piles ultimately leads to the propagation of a slip surface and the global failure of the embankment. The parametric analysis indicates that increases in the pile stiffness and the embankment load result in a higher tensile stress within the piles and a change in the failure mechanism from shear failure to bending failure. In addition, a failure envelope is proposed to determine the failure mode of the piles.

scholarly journals Experimental Study on Bending Performance of Composite Sandwich Panel with New Mixed Core

2019 ◽  
Vol 275 ◽  
pp. 02018
Author(s):  
Jing Zhang ◽  
Xiamin Hu ◽  
Wan Hong ◽  
Bing Zhang ◽  
Chengli Zhang
Keyword(s):  
Experimental Investigation ◽  
Polyurethane Foam ◽  
Failure Mode ◽  
Shear Failure ◽  
Sandwich Panels ◽  
Tensile Failure ◽  
Bending Test ◽  
Bending Performance ◽  
Composite Sandwich Panels ◽  
Composite Sandwich

This paper presents an experimental investigation of bending performance of composite sandwich panels with new mixed core, sandwich panels were tested by four-point bending test. Parametric study was conducted to investigate the influence of different core materials on the failure mode, ultimate bearing capacity, stiffness and ductility of composite sandwich panels. The results of the experimental investigation showed that the mixed core can change the failure mode of sandwich panels. The failure mode of wooden panels is characterized by tensile failure of bottom wood, and the failure mode of composite sandwich panels with wood core is that the surface layer and core are stripped and the webs are damaged by shear, while the failure mode of composite sandwich panels with wood and polyurethane foam mixed core is the shear failure of the web. Composite sandwich panels with GFRP-wood-polyurethane foam core have better bending performance and can effectively reduce the weight of panels.

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.

scholarly journals Experimental Study of the Mechanical Characteristics of a Rock-Like Material Containing a Preexisting Fissure under Loading and Unloading Triaxial Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Taoli Xiao ◽  
Mei Huang ◽  
Min Gao
Keyword(s):  
Experimental Study ◽  
Failure Mode ◽  
Mechanical Characteristics ◽  
Failure Modes ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Tensile Failure ◽  
Underground Engineering ◽  
Inclination Angles ◽  
Loading And Unloading

An experimental study of a rock-like material containing a preexisting fissure subjected to loading and unloading triaxial compression is carried out, and the results show that the mechanical characteristics of the rock-like specimen depend heavily on the loading paths and the inclination of the fissure. The triaxial loading experiment results show that the failure strength linearly increases, while the residual strength linearly decreases with increasing inclination. Furthermore, specimens subjected to triaxial compression show an “X”-type shear failure mode. The triaxial unloading compression experimental results show that specimens with different inclination angles have various failure modes. Specimens with gentle inclinations show a tensile-shear mix failure mode, specimens with middle inclinations show a shear-sliding failure mode, and specimens with steep inclinations show a tensile failure mode. These findings can be used to forecast excavation-induced instabilities in deep underground engineering rock structures.

scholarly journals Particle Flow Simulation of the Strength and Failure Characteristics of a Layered Composite Rock-Like Sample with a Single Hole

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1132
Author(s):  
Guozhu Wang ◽  
Yu Wang ◽  
Lei Song ◽  
Hao Shi ◽  
Mingwei Zhang ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Failure Mode ◽  
Failure Modes ◽  
Shear Failure ◽  
Surrounding Rock ◽  
Tensile Failure ◽  
Practical Significance ◽  
Rock Masses ◽  
Engineering Structures ◽  
Layered Rock

Layered rock masses with holes are common in nature. Their mechanical behavior plays an important role in the safety and stability of engineering structures. However, previous studies have concentrated on a single lithological layer, and few studies have reported on the mechanical behavior of layered rock masses with holes. Based on the concept of symmetry, uniaxial compression tests and numerical simulations were performed on rock-like specimens with three layers and a hole in the interlayer. The hole was in the center of the sample and was symmetrical up and down. The influence of the thickness and strength of the interlayer on the mechanical behavior and failure processes of the layered rock masses with holes was investigated. The results show that the peak strength and elastic modulus were associated with the thickness and strength of the interlayer. Three failure modes were observed in the specimens, which were not only related to the thickness and strength of the interlayer, but also affected by the presence of the hole. When the thickness of the interlayer is small, mainly a single failure mode was observed (tensile failure or shear failure). However, when the interlayer was thick, the failure mode was tension-shear mixed failure. The failure mechanism of the specimens was primarily crack propagation at the edge of the hole. These research results can provide a basis for site selection, and the design of surrounding rock protection and support parameters, and thus have important practical significance for improving surrounding rock stability and ensuring construction safety.

scholarly journals Investigation on Pore-Fracture of Coal and Its Influence Mechanism on Tensile Failure Behavior of Coals with Bursting Proneness

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yutao Li ◽  
Qingwei Guo ◽  
Xunchen Liu ◽  
Yaodong Jiang ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Spatial Distribution ◽  
Failure Mode ◽  
Failure Process ◽  
Elastic Strain Energy ◽  
Tensile Failure ◽  
Failure Behavior ◽  
Secondary Fracture ◽  
Deformation And Failure ◽  
Influence Mechanism

Both computed tomography (CT) and notched semicircular bend (NSCB) tests are performed for coals with high and medium bursting proneness to extract the scientific expression of pore-fracture and its influence mechanism on the tensile failure behavior. The acoustic emission (AE) parameters in the sample during loading and failure are monitored, and the influence mechanism of pore-fracture on tensile failure behavior of coal is analyzed. The result illustrates that the spatial distribution feature of the pore-fracture in coals with high and medium bursting proneness is extremely different. The deformation and failure mode of the coals are affected by many factors, loading mode, notch depth and width, mechanical properties of matrix and minal, spatial distribution feature of pore-fracture, etc. The influence of primary pore-fracture in the coal on the extension and penetration of the secondary fracture could be divided into two types: bifurcation and promotion, which would cause different local damage in the sample and affect the final failure mode. The feature of acoustic emission parameters indicates that the deformation and failure process of a sample under loading could be divided into four stages: compaction stage, elastic deformation stage, displacement plastic growth stage, and post peak failure stage, which is the result of comprehensive action of many factors. The evolution process of secondary fracture is accompanied by the dissipation of elastic strain energy and the intensification of internal damage of coal, which reflects the failure process of coal.

Bearing Capacity Characteristics of Lacustrine Soft Clay Hard Shell Layer Foundation

2013 ◽  
Vol 347-350 ◽  
pp. 1203-1206
Author(s):  
Jia Jia Zheng ◽  
Li Jian Wu ◽  
Run Hua Guo
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Shear Failure ◽  
Soft Soil ◽  
Soft Clay ◽  
Soil Layer ◽  
Shell Layer ◽  
Soft Foundation ◽  
Hard Shell ◽  
Punching Failure

In order to provide a theoretical basis for the use of lacustrine soft clay hard shell layer, the first thing to do is understanding its bearing capacity characteristics. Based on the project of Nan-Mao section in Hunan provincial highway S204, combining with bearing capacity test, the bearing capacity characteristics and failure mode of hard shell foundation was comprehensively analyzed. From the field bearing capacity test, it is found that the PS curve of hard shell layer has obvious changes from elastic to plastic, while the PS curve of soft soil layer under hard shell layer just has elastoplastic stage from the beginning, and the failure mode of foundation mainly are punching failure and general shear failure. So for the quality control of lacustrine hard shell soft foundation mainly includes two aspects: the deformation and overall stability.

scholarly journals A Study of the Relationship between the Stress State and Failure Mode of Concrete Specimens

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Xinyu Liang ◽  
Faning Dang
Keyword(s):  
Internal Stress ◽  
Failure Mode ◽  
Shear Failure ◽  
Ambient Pressure ◽  
Failure Process ◽  
Failure Surface ◽  
The State ◽  
Tensile Failure ◽  
Aspect Ratios ◽  
The Relationship

An investigation of concrete specimen’s strength and its changing mechanism based on numerical simulation of the failure process of axis-stressed concrete specimens with different aspect ratios was described. The state of internal stress and growth of crack of axis-stressed concrete specimens, as well as the changing mechanism of specimen strength under different ambient pressure values, were investigated. The results revealed that specimen strength and failure surface decreased as the aspect ratio is increased. The specimen strength is dependent on the state of internal stress and decreased with decreasing ambient pressure. Additionally, the failure mode shifted from shear failure to tensile failure gradually.

scholarly journals Study on Mechanical Properties and Cracking Mode of Coal Samples under Compression–Shear Coupled Load Considering the Effect of Loading Rate

2020 ◽  
Vol 10 (20) ◽  
pp. 7082
Author(s):  
Yanlong Chen ◽  
Huidong Cui ◽  
Hai Pu ◽  
Peng Wu ◽  
Liang Chen ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Failure Mode ◽  
Inclination Angle ◽  
Shear Failure ◽  
Loading Rate ◽  
Shear Crack ◽  
Axial Stress ◽  
Failure Behavior ◽  
Inclination Angles ◽  
Cracking Mode

Under coupled compression–shear loading, the failure and instability behavior of inclined pillars is different from that of horizontal pillars. To enhance the reliability and accuracy of pillar strength design, the influence of different inclination angles and loading rates on mechanical property and the failure behavior of inclined pillar should be studied. In this paper, the combined compression and shear test (C-CAST) system was developed, and mechanical properties and macro failure behavior of coal samples under different inclination angles and loading rates were studied, and acoustic emission (AE) technology was used to determine the internal cracking mode of the sample. The results show that with the increase of inclination angle, the peak shear stress of coal sample increases gradually, while the peak axial stress and elastic modulus slightly increase first and then decrease, and reach the maximum value at an inclination angle of 5°. Within the inclination angle range of 0°–15°, with the increase of loading rate, the peak axial stress and elastic modulus of coal samples first increase and then decrease, while the loading rate corresponding to peak axial stress and elastic modulus decreases. Within the inclination angle range of 20°–25°, the peak axial stress and elastic modulus of the sample gradually decrease with the increase of loading rate. The failure mode of coal samples changes from tension-splitting failure (0°–5°), tension–shear composite failure (10°) to single shear failure (15°–25°). Meanwhile, the loading rate has little effect on the failure mode of coal samples, but has a significant effect on the failure degree. When the loading rate is 1.0 and 10 mm/min and the inclination angle ranges from 0°–5°, the proportion of tensile crack is significantly greater than that of the shear crack, and tensile failure is the main failure mode; when the inclination angle ranges from 10°–25°, the proportion of shear crack is more than 50% and increases gradually with the increase of inclination angle, and shear failure is the main failure mode. This law is consistent with the macroscopic failure mode of the sample.

scholarly journals Effect of Defects on Progressive Failure Behavior of Plain Weave Textile Composites

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4363
Author(s):  
Kyeongsik Woo ◽  
Jae Hyuk Lim ◽  
Cheolheui Han
Keyword(s):  
Failure Mode ◽  
Composite Structures ◽  
Progressive Failure ◽  
Tensile Load ◽  
Textile Composites ◽  
Unit Cell ◽  
Structural Safety ◽  
Uniaxial Tensile ◽  
Failure Behavior ◽  
Plain Weave

Various types of internal defects occur during manufacturing and handling of composite materials. It is practically impossible to manufacture composite structures without defects, making it crucial to understand the effect of defects on their failure behavior to maintain structural safety. In this work, the effect of pre-defects on the failure behavior of plain weave textile composites was studied. Unit cell configurations with symmetric, in-phase, and shifted fiber tow arrangements were considered. Inter-laced warp and fill tows and matrix pockets of plain weave unit cells were modeled in three-dimensional finite elements, and cohesive elements were inserted between all bulk elements to account for the fracture modes of the fiber and matrix direction failure of warp and fill tows, matrix pocket failure, and interface failure. Unit cell models containing pre-defects of voids, tow-matrix pocket separation, warp-fill tow separation, and cracks in the warp and fill tows were analyzed, and their effects on progressive failure behavior were investigated in terms of the interaction between fiber tow arrangements and defects. Results indicated that initial failure occurred in matrix-direction failure mode in fill tows, whereas fiber tow-matrix pocket separation was the major failure mode under uniaxial tensile load. Furthermore, failure behavior was found to be highly dependent on the fiber tow arrangement pattern and the location of pre-defects.

scholarly journals An Analytical Model for Fracture Initiation of Radial Drilling-Fracturing in Shale Formations

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 1) ◽  
Author(s):  
Yuxin Chen ◽  
Yunhong Ding ◽  
Chong Liang ◽  
Yu Bai ◽  
Dawei Zhu ◽  
...  
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Shear Failure ◽  
Fracture Initiation ◽  
In Situ Stress ◽  
Tensile Failure ◽  
Shale Formations ◽  
Biot Coefficient ◽  
Radial Drilling

Abstract Radial drilling-fracturing, the combination of radial drilling and hydraulic fracturing, can guide fractures toward the target area and effectively enhance the recovery of the low permeable reservoir. In this paper, based on the stress superposition principle, we establish an analytical model to predict fracture initiation pressure (FIP) and the shale failure mode for radial drilling-fracturing applied in shale formations. In contrast with the former studies, this model can additionally consider the failure from shale beddings and is more applicable in the shale reservoir. The model classifies the shale failure into three modes and, respectively, gives the criterion for each failure mode. Then, a series of sensitivity analyses is conducted by examining effects of various parameters. By analyzing the variation characteristic of the initiation pressures required for three failure modes, the main conclusions are as follows. Firstly, matrix failure and shear failure along bedding tend to take place when the azimuth of radial borehole is moderate. Small and large azimuths are favorable for the occurrence of tensile failure along bedding. Secondly, a high ratio of horizontal in situ stress predisposes shale to generate matrix failure, and bedding tensile failure and bedding shear failure are apt to occur when the ratio of horizontal in situ stress is low. Thirdly, with the increasing intersection angle of the radial borehole wall and bedding plane, the failure mode apt to occur changes from bedding tensile failure to bedding shear failure and then to matrix failure. Fourthly, shale prefers to yield bedding shear failure under a small Biot coefficient and generate the other two failure modes when Biot coefficient is large. Fifthly, permeability coefficient virtually has no influence on the failure mode of shale. The research clarifies the fracture initiation characteristics of radial drilling-fracturing in shale formations and provides a reference for the field application of radial drilling-fracturing.

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