scholarly journals Progressive failure analysis of slope water damage based on improved Green-Ampt infiltration model

2021 ◽  
Author(s):  
Bin Chen ◽  
Qingyang Ren ◽  
Feifei Wang ◽  
Renkun Zhang ◽  
Beilei Liu ◽  
...  
Keyword(s):  
Slope Failure ◽  
Progressive Failure ◽  
Failure Process ◽  
Small Scale ◽  
Engineering Practice ◽  
Wetting Front ◽  
Failure Characteristics ◽  
Infiltration Model ◽  
Water Damage ◽  
The Law

Abstract In order to get the law of rainwater infiltration and the law of progressive water damage, the slope of Tianshang bridge foundation in Yunnan Province is taken as the engineering basis. The site investigation of the damaged slope is carried out, The traditional Green-Ampt model is improved by considering the ponding effect of dynamic water flow on the slope surface. Based on the variation characteristics of wetting front obtained by the improved infiltration model, the progressive failure process of slope with continuous infiltration is simulated by FLAC3D software. The results show that: the water damage of Tianshang bridge slope is mainly caused by the slope absorbing a lot of rainwater in a short time, which has obvious time discontinuity characteristics in time, and shows obvious multi-layer progressive failure characteristics in failure space. The wetting front characteristics obtained by the improved Green-Ampt infiltration model are more consistent with the engineering practice, the water accumulation effect of surface water gradually weakens with the increase of the wet front depth. the slope failure develops gradually from the toe to the top and from shallow to deep, and the intermittent failure characteristics provide surplus time for the engineering treatment, the gravel soil slope should be treated after a small-scale water damage occurs.

Type of Slope Failure Identified from Pore Water Pressure and Moisture Content Measurements

2015 ◽  
Vol 744-746 ◽  
pp. 690-694
Author(s):  
Muhammad Rehan Hakro ◽  
Indra Sati Hamonangan Harahap
Keyword(s):  
Moisture Content ◽  
Pore Pressure ◽  
Slope Failure ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Failure Process ◽  
Small Scale ◽  
Content Increase ◽  
Sudden Increase ◽  
Model Slope

Rainfall-induced landslides occur in many parts of the world and causing a lot of the damages. For effective prediction of rainfall-induced landslides the comprehensive understanding of the failure process is necessary. Under different soil and hydrological conditions experiments were conducted to investigate and clarify the mechanism of slope failure. The failure in model slope was induced by sprinkling the rainfall on slope composed of sandy soil in small flume. Series of tests were conducted in small scale flume to better understand the failure process in sandy slopes. The moisture content was measured with advanced Imko TDR (Time Domain Reflectrometry) moisture sensors in addition to measurements of pore pressure with piezometers. The moisture content increase rapidly to reach the maximum possible water content in case of higher intensity of rainfall, and higher intensity of the rainfall causes higher erosion as compared to smaller intensity of the rainfall. The controlling factor for rainfall-induced flowslides was density of the slope, rather than intensity of the rainfall and during the flowslide the sudden increase in pore pressure was observed. Higher pore pressure was observed at the toe of the slope as compared to upper part of the slope.

scholarly journals Experimental Investigations on the Progressive Failure Characteristics of a Sandwiched Coal-Rock System Under Uniaxial Compression

2019 ◽  
Vol 9 (6) ◽  
pp. 1195 ◽  
Author(s):  
Jinwen Bai ◽  
Guorui Feng ◽  
Zehua Wang ◽  
Shangyong Wang ◽  
Tingye Qi ◽  
...  
Keyword(s):  
Rock Specimen ◽  
Progressive Failure ◽  
Failure Process ◽  
Local Strain ◽  
Experimental Investigations ◽  
Rock System ◽  
Failure Characteristics ◽  
Coal Rock ◽  
Mining Design ◽  
Seam Mining

Overlapped residual coal pillars, together with the surrounding rock strata, play a combined bearing role in ultra-close multiple seam mining. Global stability of the whole bearing system is significant for the mining design, construction, and operation. Laboratory uniaxial compressive experiments for different kinds of sandwiched coal-rock specimens are carried out to investigate the progressive failure characteristics and mechanisms. Results show that: (1) The mechanical behavior of the sandwiched coal-rock specimen is mainly divided into four stages during the failure process. The response of the electrical resistivity and the evolution of acoustic emission (AE) energy are in good agreement with the mechanical behaviors at different stages, which are a reflection of the global failure characteristics of sandwiched specimens. (2) The distribution of AE events and the development of local strain can provide further insight into the local failure characteristics of coal elements or rock elements in sandwiched specimens. AE events are more likely to be generated in coal elements, which can propagate across coal-rock interfaces and induce damage to rock elements in a certain area. Similarly, the unbalanced deformation characteristics of coal elements and rock elements are apparently revealed in the progressive failure process. (3) Progressive failure of a sandwiched coal-rock specimen is closely associated with the interactions between the coal elements and rock elements. Initial failure usually appears in the coal elements. At this process, the recovery of elastic deformation and the output of strain energy are observed in the rock elements, which can accelerate the rupture of coal elements. In turn, the dynamic fracture energy generated in the rupture process of coal elements can propagate into rock elements and induce damage to rock elements a certain area. (4) The experimental results are helpful for maintaining the long-term stability of a sandwiched coal-rock system in ultra-close multiple seam mining.

scholarly journals Uniaxial Compression Creep Relaxation and Grading of Coal Samples via Tests on the Progressive Failure Characteristics

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Zuqiang Xiong ◽  
Changsheng Song ◽  
Chengdong Su ◽  
Xiaolei Wang ◽  
Cheng Wang ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Yield Curve ◽  
Progressive Failure ◽  
Failure Process ◽  
Thin Sheet ◽  
Strain Curve ◽  
Mechanical Parameters ◽  
Creep Failure ◽  
Creep Tests ◽  
Failure Characteristics

An RMT-150B electrohydraulic servo testing system was used to perform uniaxial compression and uniaxial grading relaxation (creep) tests. The deformation, strength, and failure characteristics of the progressive failure process of coal samples under three loading modes were analyzed. The analysis results show that the prepeak stress-strain curve of the coal samples and the load relationships are not clear and that the whole compression process of coal still showed compression, elastic, yielding, and failure stages. The local stress drop characteristics during our relaxation creep grading tests showed no clear peak value and showed a yield curve with the shape of a conventional single plateau. The values of the mechanical parameters of axial compression were significantly higher than those obtained in the grade relaxation (creep) tests, which showed the mechanical parameters of coal samples with aging characteristics. In the relaxation (creep) tests, when the stress ratio was less than 70%, the relaxation (creep) characteristics of the sample were not clear. When the ratio of stress relaxation (creep) was more than 70% in the relaxation (creep) tests during displacement (stress) with a constant relaxation (creep) over the duration of the test, the evolution, development, and convergence of microcracks in the coal samples were observed. Relaxation (creep) stress was higher, failure duration was shorter, and the duration of failure was longer. For fully mechanized coal faces, increasing the support resistance and timely moving the support after coal cutting may prevent rib spalling accidents by reducing coal stress and exposure time in the front of the working face. Additionally, routine uniaxial compressive failures showed a simple form, having a clear tension-shear dual rupture surface. The staged relaxation creep failure testing of coal is more complex. The entire coal samples were divided into many thin-sheet debris via gradual collapse and shedding, and the number of cracks increased significantly, showing evident lateral expansion characteristics that are similar to the rib spalling characteristics in high coal mining working faces.

scholarly journals An Experimental Investigation on the Progressive Failure of Unsaturated Granular Slopes

Geosciences ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 63 ◽  
Author(s):  
Reza Darban ◽  
Emilia Damiano ◽  
Aldo Minardo ◽  
Lucio Olivares ◽  
Luciano Picarelli ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Slope Failure ◽  
Progressive Failure ◽  
Small Scale ◽  
Soil Failure ◽  
Complex Process ◽  
Local Soil ◽  
Groundwater Regime ◽  
Failure Conditions ◽  
Miniaturized Sensors

Slope failure is a complex process which depends on several factors concerning nature and properties of soil, slope morphology and structure, past stress history, groundwater regime, boundary conditions, and their changes. As a consequence, the mechanism of slope failure is typically characterized by the development of a highly non-uniform strain field, which does not allow an easy prediction of the failure conditions. Usually, the process which will bring the slope to final collapse starts with local soil failure, which then leads to formation and propagation of a shear zone, and finally to general slope failure. This mechanical process is called progressive failure. However, in spite of the progresses in the knowledge of the slope behavior, a complete framework about the progressive failure is still missing; in particular, information about the response of granular unsaturated sloping soils is very poor. This paper reports the results of a couple of small-scale experiments on slopes reconstituted with unsaturated pyroclastic soils and subjected to continuous rainfall. The use of miniaturized sensors and optical fibers provided useful data to read some aspects of the mechanics of failure.

Investigation of rainfall-induced failure processes and characteristics of wedge slopes using physical models

2020 ◽  
Author(s):  
Chia-Ming Lo ◽  
Chen-Han Chu ◽  
Yi-Xiang Su
Keyword(s):  
Physical Modeling ◽  
Slope Failure ◽  
Wedge Angle ◽  
Physical Models ◽  
Small Scale ◽  
Intersection Angle ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Free Falling ◽  
The Impact

<p>In this study, the small-scale physical modeling tests have considered the impact of the infiltration of rainfall in order to investigate the processes involved in wedge slope deformation and failure. We are conducted under controlled conditions of the intersection angle and half wedge angle. Observations obtained during each stage of deformation and failure were used to explain how gravity deformation varies on wedge slopes, and infer how rainfall influence slope failure. The results indicate that half wedge angle is a crucial factor in the deformation failure of slopes. The failure mechanisms of low intersection angle slopes (sliding model) differ considerably from those of high intersection angle slopes (free falling or toppling model). The infiltration of surface water can have a significant influence on rock layer deformation and the speed of failure. Details of the failure characteristics of wedge slope models are discussed in this paper.</p><p><strong>Keywords:</strong> physical modeling, rainfall, wedge slope, the intersection angle, half wedge angle.</p>

Progressive Deformation on Defective Pile Reinforced Slope

2017 ◽  
Vol 873 ◽  
pp. 248-253
Author(s):  
Shi Wei Hou ◽  
Shi He Ma ◽  
Xu Li Liu ◽  
Ying Liu
Keyword(s):  
Plastic Strain ◽  
Slope Failure ◽  
Progressive Failure ◽  
Failure Process ◽  
Three Dimensional ◽  
Equivalent Plastic Strain ◽  
Soil Arching ◽  
Reinforced Slope ◽  
Stress Curve ◽  
The Stability

The slopes reinforced by anti-slide piles were simulated in this paper. The setting position, pile spacing and anchorage depth of integrated piles were discussed with strength reduction method. The results show that the pile position should depart slope into two stages, and the further strain would be limited. When the spacing of the anti-slide piles is 2-3 times of pile diameter, it has a soil arching effect to wedge the soil. The anchorage depth can affect the form of the potential sliding surface. Three kinds of defective piles were studied to research deformation of slope reinforced by defective piles. The defective piles were namely expanded pile, necking pile and segregationpile. The equivalent plastic strain zone was used to judge the slope failure, and then the stability and deformation process of the three-dimensional slope were simulated. By comparing the plastic strain, safety coefficient curve and pile-soil stress curve, between the defective pile and integrated pile, the progressive failure process of the reinforced slope was analyzed, including the formation process of the macroscopic shear zone.

Study of the progressive failure of concrete by phase field modeling and experiments

2021 ◽  
pp. 105678952110014
Author(s):  
Jichang Wang ◽  
Xiaoming Guo ◽  
Nailong Zhang
Keyword(s):  
Phase Field ◽  
Progressive Failure ◽  
Failure Process ◽  
Damage Model ◽  
Concrete Fracture ◽  
Opening Displacement ◽  
Three Point Bending ◽  
Edge Notch ◽  
Modeling And Experiments ◽  
Crack Faces

In this research, experiments and numerical simulations are employed to research the failure process of concrete. Fracture experiments on three-point bending (TPB) concrete beams with a prefabricated edge notch at the middle of the beam bottom are performed using a modified rigid testing instrument. The characteristics of the crack and section are analyzed, including the crack tensile opening displacement, crack length and width, and crack faces characteristics. Also, the full curves of the force-crack tensile opening displacement (CMOD) and force-deflection of the TPB beams with the prefabricated edge notch after breakage are obtained. The phase field (PF) damage model is applied to the mixed-mode and mode-I failure processes of concrete structures through the ABAQUS subroutine user defined element (UEL). The crack path and the full curves of force-CMOD and force-deflection obtained by numerical calculations are consistent with the experimental results and the calculated results of other researchers. The influences of the mesh sizes, initial lengths, and notched depths on the TPB beam of concrete are also analyzed.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

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