scholarly journals Shallow Layer Destruction Law of Expansive Soil Slope under Rainfall and the Application of Geogrid Reinforcement

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Guan-yi Chen ◽  
Peng He ◽  
Gang Wang ◽  
Shang-qu Sun ◽  
Jie Xiao
Keyword(s):  
Shear Strength ◽  
Numerical Model ◽  
Slip Surface ◽  
Expansive Soil ◽  
Strength Distribution ◽  
Cut Slope ◽  
Distribution Law ◽  
Geogrid Reinforcement ◽  
Whole Process ◽  
Shallow Layer

A large number of instability cases and laboratory tests of expansive soil slopes show that its shallow layer destruction happens because of the insufficient shear strength under the usual action of low stress and repeated dry-wet cycles. We can obtain the strength nonlinear distribution law fitted by generalized power function based on a series of shear strength tests of expansive soil considering low stress and can construct the numerical model considering the nonlinear strength distribution by FISH, to realize the shear strength dynamic distribution with the vertical stress. Based on the numerical model, the whole-process contrastive analysis has been conducted on the stress field, the slip surface depth, and the seepage field of plain soil and reinforced expansive soil cut slope under different rainfall conditions. Besides, the mechanics characteristic of the geogrid under various design schemes has been compared and analyzed. A further explanation has been given for the expansive soil cut slope prone to shallow layer failure after rainfall and on the effect of geogrid reinforcement. The numerical results provide a reference for slope stability analysis in rainy expansive soil areas.

scholarly journals Study on factors of interface properties of axial braided C/C composite materials

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chunguang Wang ◽  
Weiping Tian ◽  
Kaining Zhang
Keyword(s):  
Shear Strength ◽  
Tensile Properties ◽  
Tensile Tests ◽  
Strength Distribution ◽  
Interface Shear Strength ◽  
Distribution Law ◽  
Interface Shear ◽  
Mesoscopic Structure ◽  
Interfacial Bonding Strength ◽  
The Difference

Abstract In order to study the influencing factors of the tensile properties of axial braided C/C composites, the interfacial shear strength of the fiber rod and matrix was studied and ejecting tests of the fiber rod were carried out. The ejecting test specimens were formed with different thicknesses to obtain the changing rule of the interface shear strength with the thickness of the sample, and the testing method for the interface shear strength of the axial braided C/C composite material. The results show that the recommended thickness of the ejecting test specimens for the interface shear strength of is four times the diameter of the fiber rod. The interface shear strength distribution law of two different batches of materials was obtained through the interface ejecting test. The mesoscopic structure characteristics and pore statistical distribution law of the hole surface after ejecting were analyzed by scanning electron microscopy (SEM), and the mechanism of the difference of the interface shear strength was obtained. The tensile properties of two different batches of materials were obtained by tensile tests. The results show that the tensile properties of the two batches of materials differ greatly. The analysis suggests that the reason for this difference is the differences in interfacial bonding strength between the fiber rod and matrix. The higher the interface shear strength, the better the tensile property of the material will be.

Gas Concentration Distribution Law in the Roadway after Coal and Gas Outburst

2015 ◽  
Vol 713-715 ◽  
pp. 314-318
Author(s):  
Chun Li Yang ◽  
Yi Liang Zhao ◽  
Xiang Chun Li ◽  
Yang Yang Meng ◽  
Fei Fei Zhu
Keyword(s):  
Concentration Distribution ◽  
Correlation Coefficients ◽  
Coal And Gas Outburst ◽  
Gas Emission ◽  
Distribution Law ◽  
Gas Concentration ◽  
Research Results ◽  
Gas Outburst ◽  
Whole Process ◽  
Secondary Disasters

Gas emission happens after coal and gas outburst, and it could cause secondary disasters in the roadway. Therefore it is necessary to research gas concentration distribution law in the roadway after coal and gas outburst, and theoretical basis for avoiding the occurrence of secondary disasters could be provided. Based on the above, Fluent is used to simulate gas concentration distribution law in the roadway during outburst. The research results show that gas velocity of the initial stage is larger in the whole process of gas outburst and gas emission impacts opposite walls in the form of jet in the roadway intersection. The flow changes direction and moves along the main airway and return airway. It produces countercurrent along the main airway. Because the pressure in the main airway is high, gas migration velocity becomes zero after a certain distance and is "back" to return airway. The higher the outburst velocity is, the longer the flow length is. Gas concentration variation with two kinds of different outburst intensities and position are regressed and it shows that correlation coefficients of power function are the highest. The research results have a certain theoretical value to prevent the occurrence of secondary disasters after coal and gas outburst.

scholarly journals Shear strength characteristics of Jerash expansive soil

2021 ◽  
Vol 3 (2) ◽  
pp. 74-80
Author(s):  
Talal Masoud
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Direct Shear Test ◽  
Shear Test ◽  
Expansive Soil ◽  
Content Increase ◽  
Direct Shear ◽  
Initial Water ◽  
Angle Of Internal Friction

The results of the direct shear test on Jerash expansive soil show the effect of the initial water content on the cohesion (c) and on the angel of internal friction ( ) [shear strength parameters].it show that, as the initial water increase, the cohesion (c) of Jerash expansive soil also increase up to the shrinkage limit, after that increase of water even small amount, decrease the cohesion of the soil. On the other hand, the results of direct shear test show also  that as the water content increase, the angle of internal friction ( )remain unchanged up to shrinkage limit , any increase of water cause a large decrease on the angle of internal friction of Jerash expansive soil.

Slope failure characteristics and stabilization methods

2007 ◽  
Vol 44 (4) ◽  
pp. 377-391 ◽  
Author(s):  
H (Joanna) Chen ◽  
S H Liu
Keyword(s):  
Numerical Model ◽  
Slope Failure ◽  
Slip Surface ◽  
Distinct Element ◽  
Distinct Element Method ◽  
Soil Nails ◽  
Failure Characteristics ◽  
Stabilization Methods ◽  
Installation Angle ◽  
Element Method

This paper presents numerical and laboratory experiments to investigate slope failure characteristics and commonly used slope stabilization methods. Using an improved distinct element method, the interparticle adhesive force is incorporated with a modified numerical model to account for the effect of suction. The model is validated through laboratory tilting box tests. Calculated slope failure angles are consistent with experimental observations. Different patterns of slip surface are also identified. Furthermore, the modified numerical model quantifies the micromechanical characteristics of the interparticle network and their evolutions during shear deformation. The calculations show that the maximum ratio of shear stress to normal stress takes place when the contact plane coincides with the mobilized plane, whereas the minimum value occurs when it is parallel to the directions of principal stresses. On this basis, we propose the optimal installation angle of soil nails along the minor principal stress (σ3) direction. The effectiveness of this approach is evaluated through tilting box tests. Two commonly used slope surface stabilization methods are also experimentally investigated.Key words: distinct element method, tilting box test, slip surface, optimal installation angle of soil nails.

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