scholarly journals Slope stability analysis in the case of probabilistic and semi-probabilistic design method

2019 ◽  
Vol 97 ◽  
pp. 04044
Author(s):  
Hubert Szabowicz
Keyword(s):  
Finite Element ◽  
Internal Friction ◽  
Design Method ◽  
Probability Distributions ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Probabilistic Modelling ◽  
Finite Element Software ◽  
Random Finite Element Method ◽  
Slope Factor

This paper addresses the issue of probabilistic and semi-probabilistic modelling of soil slopes. A slope made of cohesive-frictional soil of specific geometry was analysed as an example. Results were calculated for two methods using the Z-Soil finite element software. It has been assumed that the probability distributions of strength parameters, cohesion and internal friction angle are normal distributions with average values and coefficient of variation = 0.2. Random finite element method (RFEM) has been used for probabilistic modelling. Random fields of cohesion and internal friction angle have been generated using the Fourier series method (FSM). Monte Carlo simulation has been used to calculate the statistics of the slope factor of safety in order to determine the probability of failure. Moreover, assumed parameter distributions allowed to determine safe characteristic values used in the semi-probabilistic partial factors method. Both approaches have been compared in the article.

scholarly journals Sensitivity of Multistage Fill Slope Based on Finite Element Model

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Bingxiang Yuan ◽  
Zihao Li ◽  
Zhilei Su ◽  
Qingzi Luo ◽  
Minjie Chen ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Internal Friction ◽  
Safety Factor ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Sliding Surface ◽  
Finite Element Software ◽  
The Stability ◽  
Fill Slope

Based on the strength reduction method, the laws of slope displacement and the changing positions of the sliding surface during the filling process are studied. The model of multistage fill slope is established by the finite element software PLAXIS. The difference is compared between the slope with no reinforcement and with reinforcement under the same working condition. Sensitivity analysis is carried out from two aspects which are internal factors and external factors. The finite element analysis shows that the settlement of the multistage fill slope with no reinforcement is mainly concentrated on the right side of the slope and gradually decreases with the increase of the filling height. The position of the sliding outlet is located at the joint of the first and the second grade of the slope. The effect of the reinforcement on the sliding surface is ideal. It is obvious that the reinforcement can supply the slope with a better position of the sliding surface, which is beneficial to the stability of the slope. The sensitivity analysis shows that unit weight, ratio of slope, and height of each grade are negatively correlated with the safety factor. At the same time, the platform width, cohesion, and internal friction angle are positively correlated with the safety factor. The internal friction angle has the greatest influence on the stability of the slope. Besides, the platform width and the height of each grade should be controlled at about 4 m. The sensitivity analysis provides a reference for the design of the multistage filling slope.

scholarly journals Study on Impact Parameters of Rigidity and Flexibility for Buried Corrugated Steel Culvert

2014 ◽  
Vol 8 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Baodong Liu ◽  
Zongmin Liu ◽  
Miaoxin Zhang ◽  
Quanlu Wang
Keyword(s):  
Finite Element ◽  
Internal Friction ◽  
Deformation Modulus ◽  
Earth Pressure ◽  
Steel Structures ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Steel Pipe ◽  
Inertia Moment ◽  
Finite Element Program

Buried corrugated steel culverts are universally regarded as a structure with strong deformation adaptability and dispersed the upper load by corrugated steel structures surrounding soil constraints to enhance the carrying capacity and the use of soil-structure interaction. A lot of factors influence the earth pressure of the buried corrugated steel culvert, such as culvert stiffness, physical characteristics of the backfill (bulk density, deformation modulus and internal friction angle), geometry of structure and backfilling height. The finite element program of ANSYS has been used to research the elastic modulus, Poisson’s ratio, internal friction angle of soil, inertia moment of corrugated steel plate and pipe diameter affect the rigidity and flexibility of buried corrugated steel culvert. By defining path lines in the finite element post-processing, extracting and comparing the horizontal and vertical directions soil displacements along the lines, and doing impact pa-rameter analysis. Classification for flexible and rigid pipes of the buried corrugated steel pipe culvert structure has been made according to the analysis results. A theoretical reference has been provided for the design and construction of the buried corrugated steel pipe culverts.

Testing of Strength Parameters and Deformation Parameters of Surrounding Rock and their Distributions

2011 ◽  
Vol 261-263 ◽  
pp. 1360-1364 ◽  
Author(s):  
Chun Ling Yan ◽  
De Xin Ding ◽  
Yi Qun Tang ◽  
Zhong Wei Bi
Keyword(s):  
Tensile Strength ◽  
Internal Friction ◽  
Normal Distribution ◽  
Lognormal Distribution ◽  
Hypothesis Test ◽  
Probability Distributions ◽  
Hanging Wall ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Test Method

Cores were taken from the hanging wall of the III -1 ore body at Kangjiawan Lead, Zinc and Gold Mine. 50 samples for compression and tension tests were fabricated. 50 compressive and 50 tensile strength values were obtained by RMT-150B testing systems. The probability distributions for the compressive and tensile strength were tested by the hypothesis test method. It proves that uniaxial compressive strength follows normal distribution and tensile strength follows the lognormal distribution. And it proves that elastic modulus and Poson’s ratio follow normal distribution. 50 pairs of cohesion and internal friction angle were obtained by randomly drawing a uniaxial compressive and tensile strength samples from 50 measured values. Cohesion follows lognormal distribution and internal friction angle follows normal distribution through hypothesis test method. With the results, some references can be conveniently provided for prediction of the strength and distribution of similar rocks in related geotechnical projects.

Back-analysis of geophysical flows using three-dimensional runout model

2018 ◽  
Vol 55 (8) ◽  
pp. 1081-1094 ◽  
Author(s):  
R.C.H. Koo ◽  
J.S.H. Kwan ◽  
C. Lam ◽  
G.R. Goodwin ◽  
C.E. Choi ◽  
...  
Keyword(s):  
Finite Element ◽  
Internal Friction ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Friction Angle ◽  
Geophysical Flows ◽  
Internal Friction Angle ◽  
Case Histories

Predicting the mobility and delineating the extent of geophysical flows remains a challenge for engineers. The accuracy of predictions hinges on the reliability of input parameters of runout models. Currently, limited field data for landslide case histories are available for benchmarking the performance of runout models. Key rheological parameters, such as the equivalent internal friction angle, cannot be measured directly using laboratory experiments and must instead be determined through back-analyses. A series of dynamic back-analyses was carried out for notable landslide case histories in Hong Kong, accounting for the effects of pore-water pressure on the equivalent internal friction angle, using a three-dimensional finite-element mobility model. The recorded and simulated run-out distances, as well as lateral spreading, were compared. Results reveal that the back-analysed equivalent internal friction angles resulting from open-hillslope failures and from channelized geophysical flows range from 25° to 30° and 15° to 20°, respectively. This is attributed to incised geophysical flow channels having an elevated water head and higher degree of saturation compared to open-hillside slope surfaces, wherein the induced elevated pore-water pressure profoundly lowers the equivalent internal friction angle. The back-calculated values may be useful for finite-element-based design of mitigation measures.

Characterization of Shear Strength and Interface Friction of Organic Soil

2020 ◽  
Vol 857 ◽  
pp. 203-211
Author(s):  
Majid Hamed ◽  
Waleed S. Sidik ◽  
Hanifi Canakci ◽  
Fatih Celik ◽  
Romel N. Georgees
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Friction Angle ◽  
Structural Materials ◽  
Organic Soil ◽  
Internal Friction Angle ◽  
Interface Friction

This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.

scholarly journals Influence of Structural Plane Microscopic Parameters on Direct Shear Strength

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yanhui Cheng ◽  
Weijun Yang ◽  
Dongliang He
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Stiffness Ratio ◽  
Structural Plane

Structural plane is a key factor in controlling the stability of rock mass engineering. To study the influence of structural plane microscopic parameters on direct shear strength, this paper established the direct shear mechanical model of the structural plane by using the discrete element code PFC2D. From the mesoscopic perspective, the research on the direct shear test for structural plane has been conducted. The bonding strength and friction coefficient of the structural plane are investigated, and the effect of mesoscopic parameters on the shear mechanical behavior of the structural plane has been analyzed. The results show that the internal friction angle φ of the structural plane decreases with the increase of particle contact stiffness ratio. However, the change range of cohesion is small. The internal friction angle decreases first and then increases with the increase of parallel bond stiffness ratio. The influence of particle contact modulus EC on cohesion c is relatively small. The internal friction angle obtained by the direct shear test is larger than that obtained by the triaxial compression test. Parallel bond elastic modulus has a stronger impact on friction angle φ than that on cohesion c. Under the same normal stress conditions, the shear strength of the specimens increases with particle size. The shear strength of the specimen gradually decreases with the increase of the particle size ratio.

Stability Analysis of Dam Slope by Double Safety Factors of Dynamic Local Strength Reduction Method

2015 ◽  
Vol 744-746 ◽  
pp. 593-596
Author(s):  
Yuan Meng
Keyword(s):  
Internal Friction ◽  
Reduction Method ◽  
Failure Process ◽  
Friction Angle ◽  
Strength Reduction ◽  
Internal Friction Angle ◽  
Material Strength ◽  
Strength Reduction Method ◽  
Strength Parameters ◽  
Local Strength

When calculating the dam slope failure process, traditional strength reduction method doesn't consider the difference of decay rate between cohesion and internal friction angle and discount the strength parameters for all elements. This paper uses two different reduction factors for material strength parameters, slope cohesion and internal friction angle. Based on the yield approach index criterion, we change the reduction region in time and put forward a double safety factor of dynamic local strength reduction method for engineering analysis of dam slope stability.

scholarly journals Stabilization of Algerian Clayey Soils with Natural Pozzolana and Lime

2017 ◽  
Author(s):  
Khelifa Harichane ◽  
Mohamed Ghrici ◽  
Said Kenai
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Plasticity Index ◽  
Engineering Properties ◽  
High Plasticity ◽  
Expansive Clay ◽  
Clayey Soils ◽  
Natural Pozzolana

Cohesive soils with a high plasticity index present difficulties in construction operations because they usually contain expansive clay minerals. However, the engineering properties of soils can be improved by different techniques. The aim of this paper is to study the effect of using lime, natural pozzolana or a combination of both lime and natural pozzolana on plasticity, compaction and shear strength of two clayey soils classified as CH and CL according to the unified soil classification system (USCS). The obtained results indicated that for CH class clay soil, the plasticity index decreased significantly for samples stabilized with lime. On the other hand, for the soil classified as CL class clay, a high decrease in the plasticity index value was observed for samples stabilized with natural pozzolana compared to those stabilized with lime. Also, both the cohesion and internal friction angle in lime added samples were demonstrated to increase with time. The combination of lime and natural pozzolana exhibits a significant effect on the enhancement of both the cohesion and  internal friction angle at later stages. The lime-natural pozzolana combination appears to produce higher shear strength parameters than lime or natural pozzolana used alone.

scholarly journals Effect of Glutinous Rice Slurry on the Reinforcement of Silt in the Yellow River Basin by Microbially Induced Carbonate Precipitation (MICP): Mechanical Property and Microcosmic Structure

2021 ◽  
Vol 2021 ◽  
pp. 1-23
Author(s):  
Jianwei Yue ◽  
Limin Zhao ◽  
Baoxi Zhang ◽  
Qingmei Kong ◽  
Siyuan Wang ◽  
...  
Keyword(s):  
Internal Friction ◽  
Yellow River ◽  
Friction Angle ◽  
Yellow River Basin ◽  
Reinforced Soil ◽  
Internal Friction Angle ◽  
The Yellow River ◽  
Mass Ratio ◽  
Glutinous Rice ◽  
The Yellow River Basin

The silty clay in the lower reaches of the Yellow River is characterized by loose structure, low strength, and strong capillary effect. Based on the technology of ancient glutinous rice mortar and microbial-induced calcium carbonate precipitation (MICP), experiments on optimal mass ratio of cementitious liquid to bacterial liquid and optimal concentration of cementitious liquid for MICP and improved MICP technology were carried out by measuring the production of CaCO3, and direct shear test and unconfined compressive strength test of plain silt, glutinous mixing silt, and improved silt with MICP and modified MICP were conducted. The microstructure of the reaction products of MICP and improved MICP technology were also evaluated based on scanning electron microscopy (SEM). Research results showed that the mechanical properties of silt with glutinous rice slurry were effectively improved. With the increase in the concentration of glutinous rice slurry, the strength and internal friction angle of soil samples first increased and then decreased, and the cohesion presented a linear increasing trend. When the concentration of cementitious liquid was 0.5 M and the mass ratio of cementitious liquid to bacterial liquid was 2 : 1, the amount of CaCO3 formed was the most, and the conversion rate of Ca2+ was more than 80%. The improved MICP could increase the conversion rate of Ca2+ (93.44%). An improved MICP showed that glutinous rice slurry could improve bacterial activity, increase the urease content in the bacterial solution, and promote the production of CaCO3. Silt cohesion and internal friction angle of the silt were improved by the improved MICP technology, and the strengthening effect of mechanical properties of modified MICP-reinforced soil is better than that of the MICP-reinforced soil; conventional MICP technology could also improve the soil cohesion, but the improvement in the internal friction angle was not obvious. The SEM results indicated that compared with the reaction product of MICP technology, the structure of the product of improved MICP technology is more compact, resulting in a marked reinforcement of MICP performance with glutinous rice slurry. This study provides new insights into enhancing the mechanical behaviour of MICP-treated silt in the Yellow River Basin with glutinous rice slurry.

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