Subjects -> MINES AND MINING INDUSTRY (Total: 82 journals)
 Showing 1 - 42 of 42 Journals sorted alphabetically American Mineralogist       (Followers: 16) Applied Earth Science : Transactions of the Institutions of Mining and Metallurgy       (Followers: 4) Archives of Mining Sciences       (Followers: 3) AusiMM Bulletin       (Followers: 1) BHM Berg- und Hüttenmännische Monatshefte       (Followers: 2) Canadian Mineralogist       (Followers: 7) CIM Journal Clay Minerals       (Followers: 9) Clays and Clay Minerals       (Followers: 5) Coal Science and Technology       (Followers: 4) Contributions to Mineralogy and Petrology       (Followers: 14) Environmental Geochemistry and Health       (Followers: 3) European Journal of Mineralogy       (Followers: 14) Exploration and Mining Geology       (Followers: 3) Extractive Industries and Society       (Followers: 2) Gems & Gemology       (Followers: 2) Geology of Ore Deposits       (Followers: 5) Geomaterials       (Followers: 3) Geotechnical and Geological Engineering       (Followers: 9) Ghana Mining Journal       (Followers: 3) Gold Bulletin       (Followers: 2) Inside Mining International Journal of Coal Geology       (Followers: 4) International Journal of Coal Preparation and Utilization       (Followers: 2) International Journal of Coal Science & Technology       (Followers: 1) International Journal of Hospitality & Tourism Administration       (Followers: 16) International Journal of Minerals, Metallurgy, and Materials       (Followers: 12) International Journal of Mining and Geo-Engineering       (Followers: 4) International Journal of Mining and Mineral Engineering       (Followers: 8) International Journal of Mining Engineering and Mineral Processing       (Followers: 6) International Journal of Mining Science and Technology       (Followers: 4) International Journal of Mining, Reclamation and Environment       (Followers: 6) International Journal of Rock Mechanics and Mining Sciences       (Followers: 9) Journal of Analytical and Numerical Methods in Mining Engineering Journal of Applied Geophysics       (Followers: 18) Journal of Central South University       (Followers: 1) Journal of China Coal Society Journal of China University of Mining and Technology       (Followers: 1) Journal of Convention & Event Tourism       (Followers: 6) Journal of Geology and Mining Research       (Followers: 10) Journal of Human Resources in Hospitality & Tourism       (Followers: 9) Journal of Materials Research and Technology       (Followers: 2) Journal of Metamorphic Geology       (Followers: 17) Journal of Mining Institute Journal of Mining Science       (Followers: 5) Journal of Quality Assurance in Hospitality & Tourism       (Followers: 6) Journal of Sustainable Mining       (Followers: 3) Journal of the Southern African Institute of Mining and Metallurgy       (Followers: 6) Lithology and Mineral Resources       (Followers: 4) Lithos       (Followers: 11) Mine Water and the Environment       (Followers: 6) Mineral Economics       (Followers: 2) Mineral Processing and Extractive Metallurgy : Transactions of the Institutions of Mining and Metallurgy       (Followers: 14) Mineral Processing and Extractive Metallurgy Review       (Followers: 5) Mineralium Deposita       (Followers: 4) Mineralogia       (Followers: 2) Mineralogical Magazine       (Followers: 1) Mineralogy and Petrology       (Followers: 5) Minerals       (Followers: 2) Minerals & Energy - Raw Materials Report       (Followers: 1) Minerals Engineering       (Followers: 14) Mining Engineering       (Followers: 7) Mining Journal       (Followers: 4) Mining Report       (Followers: 3) Mining Technology : Transactions of the Institutions of Mining and Metallurgy       (Followers: 4) Mining, Metallurgy & Exploration Natural Resources & Engineering Natural Resources Research       (Followers: 5) Neues Jahrbuch für Mineralogie - Abhandlungen       (Followers: 1) Physics and Chemistry of Minerals       (Followers: 4) Podzemni Radovi Rangeland Journal       (Followers: 4) Réalités industrielles Rem : Revista Escola de Minas Resources Policy       (Followers: 4) Reviews in Mineralogy and Geochemistry       (Followers: 5) Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica Rock Mechanics and Rock Engineering       (Followers: 9) Rocks & Minerals       (Followers: 5) Rudarsko-geološko-naftni Zbornik Transactions of Nonferrous Metals Society of China       (Followers: 9)
Similar Journals
 Geotechnical and Geological EngineeringJournal Prestige (SJR): 0.611 Citation Impact (citeScore): 1Number of Followers: 9      Hybrid journal (It can contain Open Access articles) ISSN (Print) 0960-3182 - ISSN (Online) 1573-1529 Published by Springer-Verlag  [2656 journals]
• Evaluation of Axial Performance of Hollow Bar Micropiles Constructed with
Different Drill Bit to Hollow Bar Diameter Ratio
• Abstract: Hollow bar micropiles (HBMP) have been popular for some time due to their fast installation and efficient load transfer mechanism. In the construction of HBMP, it is common practice to use a diameter ratio of drill bit/ hollow bar (Db/Dh) between 2 and 2.5. However, increasing the drill bit diameter should increase the micropile diameter and hence may enhance its performance and increase its capacity for a minimal increase in cost. In this study, a field testing program was conducted on six single HBMP with two different (Db/Dh) ratios installed in sand to investigate their performance. The ratio Db/Dh was increased from 2.25 to 3 by increasing the drill bit diameter for the same size hollow bar. The micropile length was 6 m, with 0.25 m free standing above ground. The micropiles were subjected to compression and tension load tests. The results demonstrated that increasing Db/Dh to 3 improved the micropiles performance and increased their compression and uplift capacities: the stiffness increased by 38% and 32% in compression and uplift, while the capacity increased by 17% and 22.5%, respectively. The compressive load–displacement response of micropiles was slightly stiffer than the uplift response and their ultimate compressive capacity was slightly higher than their uplift capacity.
PubDate: 2021-06-01

• Failure Characteristics of Complicated Random Jointed Rock Mass Under
• Abstract: Most natural rock masses contain a large number of random joints and fissures, and most of the rock masses at the rock engineering are commonly in both compression and shear stress environment. However, the research on the failure characteristics of complex random jointed rock mass under compressive-shear loading is still limited. To address this gap, this paper uses the particle flow code 2D to establish a discrete fractured rock mass model and carry out a series of numerical tests with different compressive-shear angles (α) and different joint geometric parameters. The effects of compressive-shear angle and joint geometric parameters on the strength and failure characteristics of fractured rock masses are studied. The results indicate that with the increase of α, the peak strength of the specimen decreases gradually, and the failure mode changes from the composite shear failure mode (Mode-I) to a plane shear failure mode (Mode-II) and then to intact shear failure mode (Mode-III). Specifically, the three failure modes occur in the specimens with α = 15°, 30° or 45°, 60°, respectively. The existence of joints affects stress distribution on rock mass during the loading process. Furthermore, the stress at the joint tip is relatively concentrated, while on both sides of the joint is smaller. Three kinds of crack coalescence patterns are observed: tensile, shear, and tensile-shear mixed coalescence. The inclination angle of the rock bridge between adjacent joints affects the specific type of coalescence.
PubDate: 2021-06-01

• Mechanism of Overlying Crack-Stress Evolution When Mining on the Dual
Fault Zone
• Abstract: To study the fissure-stress evolution law of overburden rock in the process of working face advancing in the dual fault area. This paper took the geological occurrence condition and actual mining situation of working face 21,129 of Tucheng mine as the engineering background. The method of similarity simulation combined with field measurement was adopted. The evolution law of the stope fissure field, the stress variation trend of roof fault, and migration characteristics of overlying strata in the process of stope mining through dual faults were studied. The results showed that: Dual faults had a large effective area on the surrounding rock of the stope, the surrounding rock movement in the affected area was intense. When the working face advanced to the fault F2 area, the energy generated during the surrounding rock movement of the fault F2 was transferred to the fault F1, which intensified the activity of the rock in the fault F1 area. The activation of the fault F2 caused the fissures in the surrounding rocks of the fault F1 to expand further. The surrounding rock of the stope changed from a single-fault action mode to a double-fault joint action mode. According to the degree of development of cracks in the roof of the overlying strata, the stope’s different positions were sorted from large to small as follows: fault activated fracture zone > central dual fault zone > open-off cut zone > middle of the non-fault affected zone. The field measured data showed that the area affected by the dual fault was composed of “high-pressure area” and “low-pressure area.” The working resistance value of hydraulic support was higher than that of the non-fault affected area. The law of fracture development and distribution in overlying strata of stope in similarity simulation experiments were consistent with the law of roof pressure measured in the field.
PubDate: 2021-06-01

• Grouting Material for Broken Surrounding Rock and its Mechanical
Properties of Grouting Reinforcement
• Abstract: Aiming at the shortcomings of traditional grouting materials, such as large influence on water content, large volume shrinkage in the late stage, poor resistance to dynamic water dispersion, and high cost, CGS grouting material is proposed based on the requirement of grouting treatment of broken surrounding rock. The CGS grouting materials with different mixing ratios were designed by orthogonal experiment, and the parameters such as strength, water separating proportion, viscosity and setting time of different blending materials were determined. Weighing the performance of all aspects of the slurry, the ratio of the slurry was determined: the water-cement ratio was 60%, the ratio of gypsum to cement was 15%, and the ratio of water–glass cement was 5%. In order to simulate the effect of grouting reinforcement in the field, the grouting reconstruction experiment of the broken rock mass was carried out in the laboratory. The results show that the CGS slurry is used to reinforce the broken fine sandstone, and the brittleness of the rock mass is obviously ductile. It has stronger plasticity and deformation resistance and can be stable within a large deformation range.
PubDate: 2021-06-01

• Discussion on the Multi-Solution of Three-Dimensional Slope Safety Factor
• Abstract: The limit equilibrium method cannot yield a unique value of safety factor in three-dimensional (3D) analysis of slope. However, the calculated value of safety factor according to limit equilibrium method directly determines the design of slope engineering. So, the study of multi-solution of three-dimensional slope safety factor may help people to judge further the reasonableness of the computation results and select the range of safety factor’s possible values. In this paper, the initial distribution of normal stresses over the sliding surface is assumed, which is then modified by a function involving four parameters to satisfy force and moment equilibrium conditions of the sliding body. Then, according to a series of assumed safety factors, the corresponding minimum value of the normal stress of sliding surface is calculated by force and moment equilibrium conditions of the sliding body. Then the reasonable range of slope safety factor is justified according to the reasonableness of the normal stress distribution over the sliding surface. The calculation results of engineering examples show that the reasonable range of safety factor for symmetric slopes is between 8 and 12% and that the reasonable range of safety factor for asymmetric slope is over 30%. Therefore, it is necessary to further verify the rationality of normal stress for the safety factor of three-dimensional asymmetric slope in order to further apply it to engineering.
PubDate: 2021-06-01

• Cyclic and Dynamic Behavior of Sand–Rubber and Clay–Rubber
Mixtures
PubDate: 2021-06-01

• The Equivalent Modulus of Elasticity of Soil Mediums for Designing Shallow
Foundations
• Abstract: As known, in a Winkler type of analysis the soil medium underneath the foundation is violently replaced by a row of parallel springs having constant ks. For the effective calculation of the latter, which is called the modulus of subgrade reaction, the two elastic constants of the soil (the elastic modulus, E and the Poisson’s ratio, ν) must be known. Although for homogenous soils this generally seems not to be a problem, the same does not stand for stratified mediums or mediums with linearly increasing modulus with depth. In addition, in a Winkler type of analysis, the proper pair of elastic constant values of soil should be selected. This refers to a Poisson’s ratio value equal to zero corresponding to the deformation pattern of springs (compression with no lateral expansion) and the respective modulus. In the present paper a method for calculating the equivalent elastic constants for the above mentioned mediums is proposed based on the theory of elasticity combining the principle of superposition. Various cases are considered, since the equivalent modulus, Eeq, depends on the rigidity and the shape of the footing. As shown, the derived Eeq values not only return reliable settlement results, but also settlement profiles that are similar to those corresponding to the original soil mediums.
PubDate: 2021-06-01

• A Review to Develop new Correlations for Geotechnical Properties of
Organic Soils
• Abstract: Organic soils are considered one of the most problematic soils due to their high compressibility and low shear strength at small strains. Characterizing organic soils based on their simple index properties is useful for the preliminary design stages of construction projects. There are three main index properties used for assessing organic soils properties, namely: the water content, the organic content, and the fiber content. Organic soils are distinguished by their relatively high water content. The organic content includes the carbonaceous and combustible components. Whereas the fiber content accounts for the presence of fibers in organic soils based on their botanical composition and the degree of decomposition. The data available in literature regarding organic soils parameters (index, compressibility and shear strength) were collected and analyzed in this study to obtain new correlations between the different organic soil parameters, and the simple index parameters (water content and organic content). The available correlations found in the literature depend on relating a certain parameter with either the organic content or water content. However, the organic content and the water content are related. Hence, the proposed correlations presented in this study aim to connect the particular soil parameter with both the water content and the organic content, using the same equation. Unfortunately, there is not much data in the literature about the soil texture or fiber content, and their relation with other parameters. Hence, all the proposed correlations in this study are not considering the fibre content or the soil fabric.
PubDate: 2021-06-01

• New Systematic Method to Determine Elastic Constants and Crack Propagation
Thresholds of Brittle Rocks Under Triaxial Compression
• Abstract: Elastic constants and crack propagation stress thresholds of brittle rocks are important mechanical properties for engineering applications. However, these properties are currently determined using methods with subjective interpreting procedures, which create cognitive biases leading to a higher degree of uncertainties. In this study, triaxial compression tests were conducted on Weber Sandstone collected from the Rock Springs Uplift, Wyoming. Nine rock specimens were treated in different geochemical conditions and tested for three different confining pressures at an in-situ pore pressure and temperature. A new method is proposed to systematically determine elastic constants and crack stress thresholds using linear and cubic regression functions to describe the linear and nonlinear stress–strain elastic behaviors, respectively. The statistical approach implemented in this new method eliminates bias due to the subjective interpretation of the nonlinear stress–strain data. The proposed method improves the consistency of elastic constant determinations by considering the linear elastic boundary of rocks and unambiguously determines the crack initiation threshold using the cubic regression function. Eliminating the subjectivity in data analysis, the new systematic method is beneficial for studying the nonlinear rock behavior and facilitating engineering applications.
PubDate: 2021-06-01

• Model on Improved Variable Weight-Matter Element Theory for Risk
Assessment of Water Inrush in Karst Tunnels
• Abstract: This paper presents an improved risk assessment model to evaluate the risk of water inrush in karst tunnels based on matter element theory and ideal point method. The 4 first-grade evaluation indexes and 13 s-grade factors are selected to establish the evaluation index system by considering the occurrence conditions of water inrush. All second-grade evaluation indexes are quantitatively divided into four risk grades. Based on improved Analytical Hierarchy Process and Triangular Fuzzy Number, the constant weights are obtained. The variable weights are determined according to the state variable weight theory and the values of evaluation indexes. The risk grade of water inrush is recognized by the closeness degree analysis. The proposed risk assessment model was applied to 3# inclined shaft of Yuelongmen tunnel, and the accuracy of the assessment result was verified by comparing with advance geological forecast and excavation. This proposed model provides a practical tool to evaluate the risk of water inrush in karst tunnels.
PubDate: 2021-06-01

• The Improved Theory of Synergetic Action Between Anchor Support System and
Surrounding Rock-I · L · 4S Mechanism Theory and Its Application in
Tunnel Support Engineering
• Abstract: Tunnel surrounding rock support is a very complex composite structure, and its mechanical mechanism is very complex. In this paper, the interaction theory of bolt and surrounding rock, the theory of integral anchorage structure and the theory of tunnel anchorage coordination are analyzed. On this basis, the theory of tunnel anchorage coordination is improved and the improved synergetic action anchoring theory (I·L·4S) is proposed. The deformation and internal force results of the supporting bolt and lining in the model test completed by the author are analyzed, and the correctness of the proposed theory is verified. Through the analysis, the tunnel support system is a composite structure. On the one hand, the anchorage system provides radial binding force for the shallow surrounding rock, and transfers the additional load of the shallow surrounding rock to the deep surrounding rock to mobilize the bearing capacity of the surrounding rock; on the other hand, it forms a certain arch effect around the tunnel to assist the surrounding rock load. The essence of the interaction between the anchorage system and the composite surrounding rock structure, the parameter matching of the single support type of the bolt and the synergistic effect between the bolt and the lining are essentially deformation coordination and reasonable distribution of the surrounding rock load. The mechanism of bolt is insert lock stretch self-bearing support squeeze. The synergistic effect of anchoring composite structure has obvious effect on eliminating or reducing surrounding rock fracture, and the overall stability of tunnel has been greatly improved after the implementation of composite structure.
PubDate: 2021-06-01

• Geostatistics-Based Method for Irregular Mineral Resource Estimation, in
Ouenza Iron Mine, Northeastern Algeria
• Abstract: Geostatistical techniques are usually practical in the development and production stages of mining projects. The Ouenza deposit is the main iron ore sources for the Algerian steel industry. This deposit suffers from heterogeneity in its mineral contents yet essential to obey to the market standards and requirements. The effective exploitation of this type of deposit is a major concern of mine managers. The variability and the content disparity in the iron ore require an in-depth scientific study. To estimate the iron ore reserves of the Ouenza deposit, an ordinary 3D kriging based geostatistical method is used to analyze the 207,723 block value in Surpac 6.2 software. The results have shown a significant variability in the iron content, which can be classified into three classes. The first class (poor ore) from 30 to 40% of iron content; the second class (medium ore) between 40 and 50%, and the third class (rich ore) from 50 to 60%. Their quantitative proportions are estimated at 1.1 MT for poor ore, 4.9 MT for medium and 2.6 MT for rich ore. For the planning of the extraction work, we use a graphic method to obtain a product of regular content during the exploitation phase of the deposit. This method gives countless solutions to exploit this type of deposit without resorting to the installation of processing plants. This is key to effective production development and accurate projection of raw materials for production.
PubDate: 2021-06-01

• Study on Shear Strength of Cement Face Between Rock and Concrete
• Abstract: The samples of slightly weathered granite drilled before the construction of Runyang suspended bridge's north anchorage are used as the research object in this paper. Through a lot of shear strength tests of concrete-bedrock rough cement face, the influence of the cement face roughness on the shear strength, shear deformation characteristics and shear failure mechanism were systematically studied. The results show that: The post-peak stress–strain curves of smooth and rough cement faces are obviously different. The shear stress–strain curve of cement face can be generalized into 3 types. The shear stress–strain model of rough cement face is the most general form, and the smooth cement face and no cementation are its special cases. The empirical relation between cement face roughness JRC and shear strength parameters is established by the fitting of experimental data. When the cement face is climbing, the internal friction angle increases with the climbing angle. When the climbing angle is constant, the increase of cohesion is positively correlated with the ratio of fluctuation difference and wavelength. When the climbing thrust is equal to the gnawing thrust, the specimen is transformed from climbing to gnawing.
PubDate: 2021-06-01

• Generation and Dissipation of Excess Pore Water Pressure During CPTu in
Clayey Soils: A Numerical Approach
• Abstract: Do all the clayey soils have the same behavior in terms of the generation and dissipation of excess pore water pressure during the piezocone penetration process' To find the answer, a coupled numerical simulation of CPTu in clays based on finite element analysis is presented in this paper. In this regard, the numerical modeling is verified by some laboratory tests on the samples with known initial conditions and stress states as well as field measurements of piezocone testing. Generation of excess pore water pressure during the penetration process is then investigated at different locations around the cone. This study encompasses piezocone penetration in both normally consolidated and heavily overconsolidated clayey soils. The dissipation of induced excess pore water pressures is also examined by stopping the cone after penetrating into the soil. The obtained results show that the measured excess pore water pressure at the cone shoulder is a key parameter for interpreting the soil behavior in terms of the generation and dissipation of excess pore water pressure around the piezocone during the penetration process. Caution should, therefore, be exercised to use existing correlations for estimating the flow characteristic parameters of cohesive soils (e.g. the coefficients of permeability and consolidation) from the piezocone test results.
PubDate: 2021-06-01

• Identification of the Main Control Factors and Failure Modes for the
Failure of Baiyuzui Landslide Control Project
• Abstract: The failure of landslide control project presents a deformation that continues to develop along the crack system, and the continuous failure of mechanical balance of the sliding body at the microscopic level. This paper takes the control project of the Baiyuzui landslide as an example, the main control factors for different deformation stages of the landslide are analyzed by the response surface method and the finite element method. Based on the numerical simulation results and field investigation data, the mechanical state and the transformation mechanism of failure modes of the landslide are discussed. The results indicate that slope shape and heavy rainfall are the main control factors for the failure of control project. In the initial excavation stage, the landslide is in a local slow regressive sliding failure mode; after the alteration of slope shape, the increment of sliding force promotes the transformation of failure mode to an entire intense progressive sliding; subsequently, excavation at the rear part reduces the rainwater infiltration path. The increment and dissipation of pore water pressure changes the failure mode of landslide to an entire slow progressive sliding mode. In the whole deformation process of landslide, the main control factors and failure mode vary with the control project progress. The findings of this study will provide experience and knowledge for control project of landslides.
PubDate: 2021-06-01

• Study on Monitoring Technology of Surrounding Rock in Deep Layered Roadway
Based on Constant Resistance and Large Deformation Bolt
• Abstract: The stability monitoring of surrounding rock in layered roadway is an important method to ensure the safety of deep mining coal mine. In view of the actual situation of roadway stability monitoring, based on similarity theory, the deep roadway model is built and small-sized ordinary bolts and constant resistance and large deformation (CRLD) monitoring bolts are developed to detect the mechanical real-time information of surrounding rock in the model, the accurate measurement information of the displacement field and the force value of the bolts are obtained. According to the time series characteristics of the deformation field and the force curves of the monitoring bolts, the criterion of stability and instability pattern of surrounding rock in deep layered roadway are studied. The results show that the force monitoring method based on CRLD bolt is superior to displacement monitoring, the force monitoring curve of CRLD bolt can be divided into stable mode and instability mode, the characteristic of stable mode curve is rising slowly and the instability model with rapid rising and falling stages. The stability monitoring system of roadway with CRLD bolt is developed and applied in deep rock roadway, it has been proved by field practice that the early warning of surrounding rock instability of deep layered roadway is feasible.
PubDate: 2021-06-01

• Research on Excavation and Stability of Deep High Stress Chamber Group: A
Case Study of Anju Coal Mine
• Abstract: As the underground transportation hub and power center, the stability of chamber group is one of the key points of coal mine construction. With the increasing of mining depth, it is more and more difficult to control the stability of roadway and chamber in coal mine, especially in the mining process. Because the excavation of chamber group is a dynamic and multi factor coupling process of, it is necessary to adopt dynamic construction mechanics to optimize the excavation scheme. Therefore, based on the engineering background of − 1155 m level at Anju coal mine in Shandong, the numerical model of deep high stress chamber group is established. Then the interaction of adjacent roadways in the process of excavation and the stress superposition of chamber intersection are studied. The excavation process of the chamber group is divided into three phases, and the construction optimization scheme is formulated. Through numerical simulation, the stress and plastic zone of each excavation scheme are analyzed, and the optimal construction sequence of each phase is determined. Finally, through the field implementation and engineering application, the optimal excavation scheme of tunnel group design is proved. The results provide a scientific basis for the excavation of deep high stress caverns and the improvement of surrounding rock support. At the same time, it also has a good reference significance for other similar underground engineering.
PubDate: 2021-06-01

• Obtaining Suction Distribution Within Vadose Zone of Highway Pavement
System in Southwestern Nigeria Using Physico-Empirical Approach
• Abstract: The stability of the pavement system on old Ogbomoso-Ilorin road in southwestern Nigeria basement complex was investigated. This was carried out by estimating the suction, degree of saturation and effective stress of the soils within vadose zone from soil–water characteristic curve (SWCC) and suction stress characteristic curves (SSCCs) employing physico-empirical approach. For this purpo se, the grain-size distribution (GSD) curves of forty two disturbed soil samples, scooped from borings at anomalously low resistivity points delineated by 2-D Electrical resistivity imaging were fitted using empirical equation. Permeability and Atterberg limits tests were also carried out for engineering classification of the subsoil. The GSD curves indicated the soils are uniformly-, poorly- and gap-graded. The permeability of the soils ranged within 1.13 × 10–6 − 9.35 × 10–5 m/s suggests very fine sands, silts/clay-silt laminate of poor sub-drainage. The intermediate suction range values obtained from SWCCs were less than 150 kPa indicate matric suction. The soils suction; 1.053–79.529 kPa, varied with air entry values; computed (1.350–3.907 kPa) and estimated (0.406–3.672 kPa), indicating the soils could shrink. The high suction gradient; 0.223–12.403%/kPa, indicates decreased evaporation flux, the ability of the soils to generate flow and suggests the soils are deformable. The SSCCs indicated the degree of saturation at which minimal soils deformation could occur varied between 0.230 and 0.560 with maximum suction stress of 1.9–8.0 kPa. The presumed equilibrium suction of the area within the range 17.365–79.529 kPa was relatively high compared with suctions of all other soils. This indicates decreasing suction and hence significance shrinkage of the soils. The pavement materials properties would therefore have undergone significant volume change and impaired the stability of the pavement.
PubDate: 2021-06-01

• Failure Mechanical Characteristics of Rock with Different Hole Shapes
• Abstract: Due to the role of geological structure, the underground rock contains a large number of holes. In order to study the influence of the hole on the mechanical characteristics of the rock failure, the numerical simulation analysis of the intact rock and the rock with three shapes holes(circle, square, triangle) are carried out by using PFC2D. The results show that the rock strength varies with the shape of the hole. Circular holes have the least impact on strength and triangles have the greatest impact. At the same time, different holes shapes have different failure morphology, the intact rock sample forms a penetrating fracture zone inclined by 60°. For the circular hole, forms a through-fracture zone along the upper left and lower right corners. The square hole sample forms an "X"-shaped fracture zone along the four corners. For the triangular holes sample, the damage occurs first at the two positions of the left and right foot of the hole, and then the fracture zone is formed along the upper right corner and the two feet of the sample. Finally, theoretical analysis of stress distribution characteristics around the rock with circular holes is carried out. The compressive stress concentration occurs on the left and right sides of the circular hole, the tensile stress concentration occurs at the top and bottom boundary of the hole. And the tensile crack occurs at the top and bottom of the hole, tensile and shear mixed cracks appear on the left and right sides of the hole from numerical simulation. The crack distribution of numerical simulation is consistent with the theoretical stress analysis results.
PubDate: 2021-06-01

• Determination of a New Failure Criterion for Rock Mass and Concrete
• Abstract: The present investigation is based on a new quadratic equation that links the principal stresses σ1 and σ3 at the moment of failure, which allows to obtain the strength in rocks and brittle materials such as concrete. Through this new empirical two-dimensional failure criterion, the normal stress acting on the fracture plane is determined in the first calculation phase by solving the first order linear differential equation, and subsequently the shear streng‘th envelope. To facilitate the calculations, the expression that relates the major and minor principal stresses σ1 and σ3 at failure are defined for a parabolic equation and presented in normalized form. Thus, the algebraic curve is expressed as a function of (σ3/σc) and the parameter ξ. Where, σcrepresents the uniaxial compressive strength of intact rock (rock matrix) or concrete at 28 days, $$f_{c}^{{^{\prime}}}$$ , and on the other hand, ξ = (σt/σc) is a dimensionless parameter whose quotient is obtained by dividing the tensile strength σt by σc. Through the procedure described on this research (Focus Procedure) the parameters k1 and k2 that relate the principal stresses are determined with a good approximation grade through the relation ξ = (σt/σc), both in the intact rock condition as a function of rock mass quality index. All of this, with the additional advantage, that it is not required to know the interval of the principal failure stress (σ3, σ1) through the experimental tests.
PubDate: 2021-04-22

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