Warning Model of the Ionic Rare Earth Mine Slope Based on Creep Deformation Time Series

This paper takes the actual working conditions of leaching mining, with the Xikeng Rare Earth Mine in Anyuan County as the research object. The slope surface monitoring as a technical means is used to analyze the deformation characteristics, including cumulative displacement, velocity, and acceleration, and the leaching slope and establish an early warning system to assist with leaching production. The study shows that there are three stages in the process of ionic rare earth mine slope deformation, i.e., the initial stage with deformation velocity in 0.15 to 0.30 mm∙h-1, the speed of the uniform deformation stage fluctuating but maintaining at -0.15 to 0.15 mm∙h-1, and the accelerated deformation stage when the velocity and acceleration are 3 to 10 times or more than those of the initial deformation stage. The practice had proved that the monitoring system responded positively when an alarm based on the Local Outlier Factor (LOF) was issued so that the production process was in a safe state and no large-scale landslide disaster occurred. This study will provide theoretical and technical support for the safe and efficient mining of rare earth in situ leaching.

A FEA Method for Mathematical Calculation and Prediction Analysis Cross-sectional Ovalization of Tubes under Rotary Straightening

The section flattening phenomenon (namely Bazier effect) will occur in the large bending deformation stage of thin-walled pipe in the continuous straightening process. The maximum section flattening amount and the residual section flattening amount are important process parameters, which are the basis for calculating the subsequent process parameters of the flattening circle, and directly determine the roundness of the final pipe and the product quality. However, it is hard to be obtained by the theoretical or experimental methods. Therefore, based on the structure and process parameters of the leveler, a finite element model was built to simulate the section flattening process. Then, ANSYS/LS-DYNA software was used to dynamically simulate the bending flattening phenomenon of thin-walled pipe in the continuous straightening process, and the stress and strain nephographic of the flattening deformation zone was obtained. By recording the position curve of the key nodes in the preventing process, the section flattening amount of the thin-walled pipe in the large bending deformation stage in the continuous straightening process was determined. The simulation results show that the dynamic simulation method can effectively predict the section flattening of thin-walled pipe in the process of continuous straightening.

Tectonics of the Central Part of the Adycha-Taryn Fault Zone (Verkhoyansk-Kolyma Orogenic Belt, NE Asia)

The study area is located in the central part of the regional-scale Adycha-Taryn fault zone separating the Adycha-El’gi and Nera anticlinoria in the hinterland of the Verkhoyansk fold-and-thrust belt (central part of the Verkhoyansk-Kolyma orogenic belt). Detailed structural studies were conducted in large quarries in the lower reaches of the El’gi River (Indigirka R. basin). In the Adycha-El’gi anticlinorium, several generations of folds, faults, and cleavage are recorded. The intensity of deformation here is found to gradually increase in NE direction. The NE wall of the Adycha-Taryn fault is thought to be more strongly deformed. The results of our investigations revealed three structural parageneses. The first paragenesis includes thrusts, reverse faults, and intense NW-striking folds of the first generation. The second paragenesis consists of less intense superposed folds of the second generation, with subvertical axes, as well as sinistral strike-slip faults. The previously made assumption is confirmed about manifestation in the study area of at least two deformation stages. We also presuppose the existence of the third deformation stage in which dextral strike-slip faults were formed. A change in the intensity of tectonic deformations both along and across the Adycha-Taryn fault zone is first established. On the southwestern side of the fault zone, the intensity of deformation structures decreases from NW to SE. On the northeastern side, the deformation intensity first increases in that same direction but then tends to diminish. An assumption is made about a growing importance of reverse faults in NW direction, along the Adycha-Taryn fault zone. Orientation of paleostress axes responsible for the formation of tectonic structures in the study area is first determined. Folds and thrusts of the first deformation stage were formed under subhorizontal compression in NE direction. Sinistral strike slips and associated folds of the second deformation stage resulted from WE-oriented subhorizontal compression. The following dextral strike-slip motions occurred in the conditions of NW-directed subhorizontal compression and NE-oriented subhorizontal extension. The studied tectonic deformations were formed in Late Mesozoic time as a result of collision-accretion events in the central part of the Verkhoyansk-Kolyma orogenic belt.

Laboratory Study of Deformational Characteristics and Acoustic Emission Properties of Coal with Different Strengths under Uniaxial Compression

Acoustic emission (AE) can reflect the dynamic changes in a material’s structure, and it has been widely used in studies regarding coal mechanics, such as those focusing on the influence of loading rate or water content change on the mechanical properties of coal. However, the deformational behavior of coals with various strengths differs due to the variation in microstructure. Hard coal presents brittleness, which is closely related to certain kinds of geological disasters such as coal bursts; soft coal exhibits soft rock properties and large deformation mechanical characteristics. Therefore, conclusions drawn from AE characteristics of a single coal sample have application limitations. This paper studies the deformation patterns and AE characteristics of coals with different strengths. A uniaxial compression experiment was carried out using coal samples with average uniaxial compressive strengths of 30 MPa and 10 MPa; the SAEU2S digital AE system was used to measure the AE counts, dissipation energy, and fracturing point distributions at each deformation stage of the different coals. The results show that the bearing capacity of hard coal is similar to that of the elastic stage and plastic deformation stage, but it may lose its bearing capacity immediately after failure. Soft coal has a relatively distinct stress-softening deformation stage and retains a certain bearing capacity after the peak. The AE counts and dissipation energy of hard coal are significantly higher than those of soft media, with average increases of 49% and 26%, respectively. Via comparative analysis of the distribution and development of internal rupture points within soft coal and hard coal at 15%, 70%, and 80% peak loads, it was observed that hard coal has fewer rupture points in the elastic deformation stage, allowing it to maintain good integrity; however, its rupture points increase rapidly under high stress. Soft coal produces more plastic deformation under low loading conditions, but the development of the fracture is relatively slow in the stress-softening stage. We extracted and summarized the AE characteristics discussed in the literature using one single coal sample, and the results support the conclusions presented in this paper. This study subdivided the deformation process and AE characteristics of soft and hard coals, providing a theoretical guidance and technical support for the application of AE technology in coal with different strengths.

Research on Creep Behavior of Three-Point Bending Specimen with Fixed Constraints at the Large Deformation Stage

Three-point bending specimen with fixed constraints (TPBSF) is a novel small specimen test technique, which can simultaneously obtain creep deformation and creep fracture data. However, the current researches are only focused on the small deformation theoretical analysis, which is contrary to the actual experiment results. In this study, the general deformation theory was introduced to analyze creep deformation behavior of TPBSF at the large deformation stage. Based on this theory, the equivalent stress and strain were analyzed. Then the feasibility and accuracy were verified by comparing with the experimental data of A7N01 aluminum alloy at 380 ?. The results show that the regressed creep parameters agree well with those from the uniaxial ones. It can be found that the equivalent stress obtained by the general deformation theory can be well used to life prediction analysis of A7N01 aluminum alloy.

The Kinematic Analysis and Bistable Characteristics of the Winding Origami Structure

In the military and aerospace fields, bistable structures with adjustable or adaptive stiffness have been widely applied. Origami structures can be used to design bistable systems due to their unique geometrical characteristics. In this paper, we investigate a special design of winding origami, which consists of a square hub in the center and compactly folded panels around it. This delicate design provides the structure a bistable property. According to its motion characteristics, the folding process of the winding origami can be divided into two stages: the mechanism motion stage and the structural deformation stage. The D-H matrix method and truss transformation method were combined to analyze the kinematic relations, and the winding origami pattern was found to have one degree of freedom. At the structural deformation stage, the mechanical response and the local panel deformation were carefully studied via both experiments and finite element simulations, and a reasonable agreement was reached. It was observed that four creases exhibited a non-uniform folding pattern during the deformation process; that is, a portion of the crease was totally flattened while the rest remained folded. The origami structure’s unique kinematic and bistable features could possibly help provide some new ideas in designing a bistable system in the future.

Experimental Study on the Relationship between Compression Stability and Deformation Localization of Viscous/Brittle Rock-Like Materials

Rock-like materials often exhibit irregular failure deformation under long-term service conditions, and the deformation and failure of asphalt and concrete materials is a serious problem that leads to subgrade failure. In this study, two different viscous/brittle rock-like materials were prepared by the in situ loading and optical speckle synchronous monitoring test method, and the evolution characteristics of the deformation field were studied during compression. The formation process of the compression deformation localization of rock-like materials and their relationship with stability were analyzed. A quantitative description of the compression deformation stage and localization characteristics of the viscous/brittle rock-like materials is presented. The results can be summarized as follows. At the initial stage of compression, the deformation localization zone of viscous/brittle rock-like materials begins to expand from the middle area to the surrounding area. Preliminary results of the deformation localization of the linear elastic deformation stage were obtained. The failure cloud image is completely formed at the peak, which is consistent with the failure physical map. The deformation process of compression can be quantitatively described using the deformation localization characteristics of rock-like materials.

Reinforced concrete slabs on yielding supports under dynamic load

The paper presents the experimental results of strength and deformability of reinforced concrete slabs on yielding supports arranged along the perimeter under the dynamic loading. Crushable ring-shaped inserts deforming at the elastic, plastic and curing stages are considered as yielding supports. The displacement, velocity and acceleration are evaluated depending on the deformation stage of yielding supports. The high efficiency is shown for the use of yielding supports, which leads to a significant reduction in the structure displacement, strain, and stress.

Relationship between advancing abutment pressure and deformation of surrounding rock in a roadway: A case study in Helin coal mine in China

The deformation stages of the working face of a mine in front of the roadway were defined based on the location of the roadway and the coal wall in different deformation zones. Observational data of the advancing abutment pressure and the surrounding rock deformation of the roadway from Helin coal mine were analyzed using least squares fitting. The results show that the distance between the boundary of the rapid deformation stage and the deceleration deformation stage and the position where the advancing abutment pressure is equal to the original rock stress is 0.8 m. The distance between the boundary of the large deformation stage and the stable small deformation stage and the peak value of the advancing abutment pressure is 0.3 m. A theoretical analysis indicated that the boundary between the rapid deformation stage and the deceleration deformation stage is located at the intersection of the advancing abutment pressure curve and the original rock stress curve. The boundary between the large deformation stage and the stable small deformation stage is located at the peak value of the advancing abutment pressure.