Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

For the loess cave characteristics, such as the thin coverage soil layer at the hole top, the poor self-stabilizing capacity, the large disturbance deformation after excavation and the easy collapse, thus in this paper, the loess cave safety factor is obtained by the method of strength reduction. And the stability calculation analysis is much more perfect. The Northwest Area Lishi loess cave is used in this paper, and the idea of strength reduction finite element method is applied, based on the Drucker-Prager yield criterion, the loess cave static stability analysis is made by the software of ANSYS.The results show that the actual situation can be reflected by the method of finite element strength subtraction. And the obtained loess cave stability coefficient is much closer to the actual steady state, thus showing the certain advantages of stability analysis.The method is also adopted in this paper. And its feasibility can be applied to the engineering practice, also a theoretical basis of reference is provided for engineering application.

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Hydraulic Tests and Interpretation of Test Data for Reno Mattresses in Open Channel Flow

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/930/1/012025 ◽

2021 ◽

Vol 930 (1) ◽

pp. 012025

Author(s):

P D Pietro ◽

M Lelli ◽

A Rahman ◽

Serkandi

Keyword(s):

Soil Erosion ◽

Control Systems ◽

Soil Layer ◽

Erosion Control ◽

Wire Mesh ◽

Unit Weight ◽

Research Results ◽

Colorado State University ◽

Soil Erosion Control ◽

The Stability

Abstract The efficacy of erosion control systems depends on preventing soil loss underneath and maintaining its integrity under the effects of the water flow. The paper presents the research results at the Colorado State University on the performance of double twisted wire mesh products, known as Reno Mattresses, used as soil erosion control systems. Mattresses were subjected to various flow conditions on a 10 m long flume placed on a soil layer. The performance against erosion was evaluated by assessing the effect of the stone motion inside the mattress combined with the condition of incipient soil erosion underneath, in relationship to the mattress thickness, the filling stone properties, and under variable hydraulic flow regimes. At the same time, confirming the stability obtained using the conventional tractive force design approach, the research results allowed to introduce a new performance limit based on incipient soil erosion underneath the revetment. Based on the research results, the authors propose to express the shear resistance of mattresses used as soil erosion control systems as a function of the filling stones’ size, uniformity, unit weight, mattress thickness, and the presence of vertical strengthening elements.

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Experimental Study on City Road Collapse under Vibrating Load

Shock and Vibration ◽

10.1155/2020/6074658 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Yuxiao Wang ◽

Gang Shi ◽

Xiaowei Tian ◽

Chaoyue Li ◽

Huanyu Cheng

Keyword(s):

Dynamic Load ◽

Static Load ◽

Soil Layer ◽

Formation Time ◽

Traffic Load ◽

Scale Model ◽

The Road ◽

Ultimate Failure ◽

The Stability ◽

Collapse Process

Underground pipeline seepage and traffic load are the important factors causing city road collapse. In this paper, eight groups of indoor scale model experiments are used to study the road collapse caused by pipeline seepage, taking into account the load type, pipeline buried depth, the distance between pipeline and loss channel, the relative position of pipeline and loss channel, and the formation time of loss channel. The results show that when the erosion channel was formed later, the underlying erosion cavity was ellipsoid, while the other erosion cavities were funnel shaped. When only the static load is applied, the time to reach the ultimate failure is longer than that when only dynamic load is applied. The smaller dynamic load can increase the stability of the soil above the seepage pipeline, while the larger dynamic load can accelerate the collapse process. With the formation time of the erosion channel increasing, the erosion void size is larger and the surface is easier to collapse. With the increase of the distance between the loss passage and the pipeline, the damage time of the road surface is also increased. The larger the thickness of the soil layer above the pipeline, the smaller the size of the underground cavity and the surface subsidence.

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Analysis of Factors Influencing Stability of Overlying Soil Layer on Thin Bedrock Based on Crack Development-Closure Test

Advances in Civil Engineering ◽

10.1155/2019/3648650 ◽

2019 ◽

Vol 2019 ◽

pp. 1-20 ◽

Cited By ~ 1

Author(s):

Guangming Wu ◽

Haibo Bai ◽

Luyuan Wu ◽

Shixin He ◽

Bin Du

Keyword(s):

Water Content ◽

Layer Thickness ◽

Crack Width ◽

Soil Layer ◽

Crack Development ◽

Sand Content ◽

Particle Composition ◽

Thin Bedrock ◽

The Stability ◽

Seam Mining

The water-blocking properties of the clay layer at the bottom of the Cenozoic overburden in China are an important factor influencing the safety of thin bedrock coal seam mining. Clay has remolding properties that are unlike the nonreversible characteristics of cracks in brittle rock, and failure cracks in clay can reclose or continue to expand under the influence of different external factors. In this work, the soil layer on top of thin bedrock is the research object, and the influences of the particle composition, water content, soil layer thickness, and crack width on the crack development-closure state of soil layer are analyzed by the orthogonal test method. Visual analysis shows that the order of influence of each factor on the stability of soil layer is the crack width, particle composition, soil layer thickness, and water content. The stability of soil layer decreases with increasing crack width and sand content and decreasing soil layer thickness; in addition, soil layer stability decreases first and then increases with increasing water content. Further variance analysis shows that the crack width and particle composition are key factors that impact the stability of soil layer and that the soil layer thickness has some influence, while the water content has little effect on the stability of soil layer. In addition, the crack will reclose when the sand content in soil is less than 50% and the crack width is less than or equal to 1.0 mm, and the soil layer is prone to further failure when the sand content in soil is more than 50% and the crack width is greater than or equal to 3.0 mm; when the soil layer thickness is 15.0 cm, its stability is better than when the soil layer thickness is 10.0 cm or 5.0 cm.

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Analysis of the Sensitivity of Impact Factors on the Stability of Expansion Freeway Slope

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.405-408.1830 ◽

2013 ◽

Vol 405-408 ◽

pp. 1830-1833 ◽

Cited By ~ 1

Author(s):

Gen Chuan Luo ◽

Zhong Ming He ◽

Xin Tong Zhao

Keyword(s):

Slope Angle ◽

Soil Layer ◽

Friction Angle ◽

Test Method ◽

Impact Factors ◽

Factors Affecting ◽

Orthogonal Test Method ◽

Main Factors ◽

The Stability ◽

Method Analysis

By analysis its own characteristics of Reconstruction and Extension freeway slope, summary and presents the main factors affecting slope stability; then use orthogonal test method, analysis the result by Range Method, it indicated that the sensibility of impact factors on the Stability of Reconstruction and Extension Freeway Slope was in the following order: the slope angle after excavation, cohesion, weight of soil layer, internal friction angle, the slope angle before excavation, Cable length, Cable spacing.

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STABILITY ANALYSIS FOR EMBANKMENTS WITH GEOELECTRICITY

Jurnal Sains dan Teknologi Mitigasi Bencana ◽

10.29122/jstmb.v15i2.4333 ◽

2020 ◽

Vol 15 (2) ◽

pp. 114-122

Author(s):

Teddy Wartono Sudinda

Keyword(s):

Stability Analysis ◽

Groundwater Flow ◽

Water Level ◽

Human Activities ◽

Soil Layer ◽

Flow Patterns ◽

Soil Density ◽

The Stability ◽

The Right

Abstract The collapse of the embankment is a problem that needs attention to find the right solution, so that the risk can be minimized. The condition of the embankment is influenced by the strength of the soil layer of the embankment, groundwater flow in the embankment, the condition of the water level of the embankment and human activities around the embankment. Changes in the quality of soil density in the embankment can form cavity zones within the embankment which cause changes in groundwater flow patterns in the embankment. The degradation of the soil layer of the embankment can cause piping, overtopping which is the cause of erosion of the embankment body and disturbs the stability of the embankment. Therefore, to determine the condition of the embankment soil layer, research on the stability of the embankment has been carried out using the geoelectric method at the location of the embankment in the Cipancuh and Penjalin reservoirs, so that an image of the embankment soil layer is obtained to determine the cavity zones in the embankment, the flow pattern in the embankment soil layer. Keywords: cavity zones, flow patterns, geoelectric methods, the stability of the embankment.

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Buckling of Piles in Layered Soils by Transfer Matrix Method

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455421501091 ◽

2021 ◽

pp. 2150109

Author(s):

Lu Zheng ◽

Tao Deng ◽

Qijian Liu

Keyword(s):

Transfer Matrix ◽

Transfer Matrix Method ◽

Matrix Method ◽

Present Method ◽

Soil Layer ◽

Layered Soils ◽

Subgrade Reaction ◽

Soil Stiffness ◽

Governing Differential Equation ◽

The Stability

The transfer matrix method is applied to the buckling of end-bearing piles partially or fully embedded in a layered elastic medium with a constant coefficient of subgrade reaction for each layer. The solution of the governing differential equation for each pile segment can be expressed as the product of a fourth-order matrix and a coefficient determinant. Using the transfer matrix method and combining the boundary conditions at both ends of the pile, the buckling load is obtained by solving the eigenvalue equation. A parametric study is performed to investigate the effects of the properties of the soil–pile system on the stability capacity of the pile. It is shown that the effects of the embedment ratio, soil layer thickness, and soil stiffness on the buckling of piles are quite significant. Several calculation examples are presented to verify the present method.

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Stability Study Using Numerical Analysis for the Panel Method Applied to the Weathered Rock Section below the National Highway

Korean Society of Hazard Mitigation ◽

10.9798/kosham.2021.21.5.213 ◽

2021 ◽

Vol 21 (5) ◽

pp. 213-220

Author(s):

Ji-Sun Kim ◽

Ja-Yeon Kim ◽

Ki-Young Eum ◽

KookHwan Cho

Keyword(s):

Numerical Analysis ◽

Soil Layer ◽

Stability Study ◽

Panel Method ◽

Measuring Instruments ◽

Tunneling Method ◽

Ground Conditions ◽

Natm Tunnel ◽

The Stability ◽

National Road

In sections with poor ground conditions, it is difficult to apply the commonly used NATM tunnel method; thus, applications of the non-open cut tunneling method are increasing. This section is a tunnel crossing area under the national road in which the Panel method is to be applied to the section where a deeply buried layer and a loose weathered soil layer are distributed. Therefore, the stability of the upper road, the amount of settlement, and the stability of the tunnel structure were reviewed for each construction stage by using MIDAS GTX. Through the installation of measuring instruments in the tunnel area, the results of the numerical analysis were reviewed and the stability during and after construction was evaluated. Therefore, it is likely that the Panel method is an appropriate countermeasure in the downtown area and in areas with soft ground sections where the application of the general tunnel excavation method is difficult.

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Sudut Tenang Tanah Pasir-Lempung Pada Kondisi Runtuh

Borneo Engineering : Jurnal Teknik Sipil ◽

10.35334/be.v4i2.1441 ◽

2020 ◽

Vol 4 (2) ◽

pp. 161-171

Author(s):

Anto Budi Listyawan ◽

Renaningsih Renaningsih ◽

Qunik Wiqoyah ◽

Aditya Galih Pradana

Keyword(s):

Soil Layer ◽

Angle Of Repose ◽

Beach Sand ◽

Merapi Volcano ◽

Fine Grain ◽

Before And After ◽

The Difference ◽

Failure Conditions ◽

The Stability ◽

External Forces

The soil layer is the combination of many types as well as the soil in the slope area. The soil in the slope is frequently a mixture of clay and sand. The stability of slope becomes dominantly an issue in the geotechnical engineering area. The collapse of the slope occurs because the gravity of external forces is exceeding the shear strength of the soil. The recent research develops the apparatus to determine the angle of repose of the sand-clay soil in the failure conditions. Sandy soil is taken from Beach and Merapi volcano. The clay added into the sand in the proportion of 0%, 5%, 10%, 15%, 20%, 25%, and 30%. The experiment is conducted by taking the height of the falling material of 15cm, 25cm, and 35 cm. Adding 0% to 15% clay brings the sand into SP Category, then adding 20%-30% makes the sand in the SC category. The Modulus if a fine grain of sand beach is smaller than Merapi sand. As the percentage of clay added to the sand higher, the difference of angle of repose of Merapi sand before and after failure is getting smaller, but it is not the case in Beach sand. The percentage of loss of volume of Merapi sand after failure is also going down as the portion of clay higher. The loss of volume of Beach sand added by clay is getting higher in failure condition..

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Large Displacement Finite Element Analysis of Submarine Slide due to Gas Hydrate Dissociation

Volume 7: CFD and VIV; Offshore Geotechnics ◽

10.1115/omae2011-49328 ◽

2011 ◽

Author(s):

Jun Liu ◽

Long Yu ◽

Xianjing Kong ◽

Yuxia Hu

Keyword(s):

Finite Element ◽

Gas Hydrate ◽

Soil Layer ◽

Element Model ◽

Large Displacement ◽

Element Analysis ◽

Hydrate Dissociation ◽

Submarine Slide ◽

Submarine Slope ◽

The Stability

Gas hydrate dissociation will reduce the stability of the submarine slope, which has been increasingly considered as a potential geohazard. In this study, a conventional geotechnical model is used to simulate gas hydrate dissociation while the thermal and geochemical effects are considered by reducing geotechnical strength parameters (c-φ) and stiffness (E). The stability analysis of submarine slope due to gas hydrate dissociation is carried out using the large displacement finite element model – RITSS (Remeshing and Interpolating Technique with Small Strain model). The strength and stiffness parameters of gas hydrates are reduced gradually after each remesh according to the strength-dissociation relationship. The large displacement analysis procedure considering dissociation is given and the effects of the thickness of the top normal soil layer on slope stability is discussed.

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