Expansion Deformation Research Articles

Experimental study on the free expansion deformation of concrete during the cooling process after being heated to high temperature

High temperatures can cause free expansion deformation of concrete. The deformation remains even when the concrete was cooled down to room temperature. In this paper, to investigate the variation of concrete free expansion during the cooling process, firstly the specimens were heated to the target temperatures of 100, 200, 300, 400, 500, 600, 700 and 800 °C, respectively in a furnace. After the target temperature was attained, the temperature of the furnace was maintained constant for 3 h. Then the specimens were allowed to cool to room temperature. The deformation of concrete in the cooling process were also measured. The results showed that the linear expansion rate (LER) of concrete at 100 and 200 °C was constant in the initial stage of the cooling process. The coefficients of thermal expansion of concrete (CTE) were −9.288 × 10−6/°C after being cooled from 800 °C down to room temperature. The LER of concrete at 300–800 °C increased slightly, and then the LER decreased gradually with the decrease of temperature. The expansion deformation of concrete at the target temperatures of 100–300 °C can be completely recovered during the cooling process. The residual deformation of concrete which was heated at temperatures above 400 °C was obvious. The residual deformation of concrete increased with the heating temperature. The residual LER of 0.036% was generated after being cooled from 400 °C down to room temperature. The residual LER of concrete after being cooled from 800 °C down to room temperature can reach 0.509%.

Experimental Study of 3D Micro-CT on Meso-Structure Evolution of Coal Samples with Different Coal Grades under the Action of Temperature

In the three-dimensional micro-CT experiment system, the room temperature is set to 300°C when different coal samples (lignite, anthracite, lean coal and gas coal) are observed for mesoscopic observation. The evolution regularity of mesoscopic structure is analyzed according to the CT scan of coal samples under different temperatures and three sections of scanning images, and by ImageJ image processing software, image processing, and analysis of the characteristics of the profile, the following conclusions are obtained: (1) Coal specimen will have an overall expansion deformation along with the rise of temperature. The sample expansion can be divided into two types: outward expansion and inward expansion. Outward expansion means that the expansion of the skeleton extends outward from the adjacent pores, while inward expansion means that the solid skeleton intrudes into the adjacent pores. When the temperature rises, the outward expansion and inward expansion occur simultaneously. The dominant expansion mode is influenced by the type of coal sample and the temperature value. (2) With the increase of temperature, coal and anthracite coal specimen pore fissure structure shows an expansion tendency before contraction, while gas coal and lean coal show reverse patterns; in addition to the above the reason of the difference vitrinite differences, one must also consider selected specimen original porosity and mechanical physical properties, such as a combination of other factors. (3) In the temperature range of 100–200°C, when the temperature increases at the same rate, lignite porosity increases the most, followed by gas coal, lean coal, and anthracite. (4) There are certain differences in the variation trends of the pixel proportions of the three sections of the coal specimen, and the temperature values of the three curves at the maximum pixel point are also different, which indicates that the expansion of each point in the coal specimen with the change of temperature is not completely synchronous, and the physical and mechanical properties of the sample are heterogeneous.

Determining the Paleostress Regime during the Mineralization Period in the Dayingezhuang Orogenic Gold Deposit, Jiaodong Peninsula, Eastern China: Insights from 3D Numerical Modeling

The Dayingezhuang orogenic gold deposit, located in the northwestern Jiaodong Peninsula, is hosted by the Zhaoping detachment fault, but the paleostress regime during the mineralization period remains poorly understood. In this study, a series of numerical modeling experiments with variable stress conditions were carried out using FLAC3D software to determine the orientation of paleostress and the fluid migration processes during the ore-forming period. The results show that the simple compression or tension stress model led to fluid downward or upward flow along the fault, respectively, accompanying the expansion deformation near the hanging wall or footwall of the Zhaoping fault, which is inconsistent with the known NE oblique mineralization distribution at Dayingezhuang. The reverse and strike-slip model shows that the shear stress was distributed in the gentle dip sites of the fault, and the expansion space occurred in the geometric depression sites of the fault, which is also inconsistent with the known mineralization distribution. The normal and strike-slip model shows that shear stress was distributed in the sites where the fault geometry transforms from steep to gentle. In addition, the expansion deformation zones appeared at sites with dip angles of 35~60° in the footwall and extended along with the NE-trending distribution from shallow to deep levels. The numerical results are quite consistent with the known mineralization, suggesting that the fault movement during the mineralization stage is a combination of the local strike-slip and the NW–SE extension in the Dayingezhuang deposit. Under this stress regime (σ1 NE–SW, σ2 vertical, σ3 NW–SE), the NE dilation zones associated with fault deformation served as channels for the ore-forming fluid migration. Based on the numerical modeling results, the deeper NE levels of the No. 2 orebody in the Dayingezhuang deposit have good prospecting potential. Thus, our study not only highlights that gold mineralization at Dayingezhuang is essentially controlled by the detachment fault geometry associated with certain stress directions but also demonstrates that numerical modeling is a robust tool for identifying potential mineralization.

Research on the Mechanism and Prevention Methods of the Drying Shrinkage Effect of Earthen Sites.

In view of the fact that it is easy for the ancient city soil site of Cai Kingdom to expand and crack when encountering water, this paper explores the methods to improve the expansion and shrinkage deformation, dry shrinkage cracks and easy water absorption characteristics of the expanded site soil based on a lime and silicone hydrophobic agent. In this paper, the expansive clay in the old city site of Cai Kingdom in Zhumadian was taken as the research object, and the dry-shrinkage fissure test of saturated expansive soil was carried out, to study the influencing factors of the dry-shrinkage cracking of expansive soil in this area. The site soil was modified with lime and glue powder, and the fissure image was quantitatively analyzed by MATLAB. The test shows that the smaller the particle size, the faster the evaporation of water and the smaller the surface fissure rate; the thicker the thickness of the soil sample, the greater the surface fissure rate and the greater the crack width; and with the increase in the number of drying and wetting cycles, the surface fissure rate of the soil sample increases. In this paper, lime and waterproof materials are used to improve the expansive soil. This not only reduces the dry shrinkage crack rate, but also improves the waterproof performance and durability of expansive soil.

Development of Expanded Steel Pipe Pile to Enhance Bearing Capacity

An expanded steel pipe pile increases the cross-sectional area of conventional micropile by expanding the steel pipe to exhibit a higher bearing capacity owing to increased frictional resistance. However, construction cases of the expanded steel pipe pile are insufficient due to the absence of equipment for expanding steel pipes inside the ground. In this study, hydraulic expansion equipment was developed to verify the reinforcing impact on the bearing capacity and field applicability of the expanded steel pipe pile. A series of laboratory and test bed experiments was conducted to measure the expansion time and deformation of carbon steel pipes by using the developed equipment. The results of these experiments demonstrated that the developed equipment has sufficient ability and constructability to be used in the field for constructing expanded steel pipe piles. Then, field load tests were performed by constructing expanded and conventional steel pipe piles to confirm the improved bearing capacity of the expanded steel pipe pile compared to that of the conventional micropile. As a result, the expanded steel pipe pile exhibited a 20.88% increase in bearing capacity compared to that of the conventional steel pipe pile.

Light-driven Bi-stable actuator with oriented polyimide fiber reinforced structure

The unique feature of bi-stable structure is that it has the inherent ability to rapidly change between two stable configurations under external stimulations, and can maintain the equilibrium state without energy consumption. Herein, we reported a light-responsive bi-stable actuator which composed of functional and support layers. Firstly, the effect of oriented polyimide (PI) fiber-reinforced polydimethylsiloxane (PDMS) composites on thermal behavior was been studied. Then, this unique thermal performance of PI fiber-reinforced PDMS in combination with the laying method ensures the formation of a bi-stable actuator. Finally, a universal but straightforward strategy to generate a light-responsive actuator with fast deformation and bi-stable characteristics was developed based on photo-thermal expansion deformation mechanism. Moreover, the actuator was fabricated by using inexpensive materials and scalable methods. Overall we believe this work may open up a new perspective for the design of light-responsive actuators and enriches the design of fast-deformation flexible bi-stable actuators.

High Temperature In Situ Optical Observation and Structural Optimization Numerical Simulation of High Nitrogen Steel (Cr18Mn18N)

As a steel with high strength, good plasticity and fracture toughness, high temperature resistance, and corrosion resistance, Cr18Mn18N is widely used in industrial engineering and military fields. However, in a high temperature environment, Cr18Mn18N needs to be subjected to higher temperature, resulting in excessive expansion deformation and larger stress, which will greatly damage the stability and service life of the material structure. In this paper, the high temperature arc wind tunnel is used to heat the high nitrogen steel material with prefabricated round structure, and the surface images of the material are collected at the temperature of 1500 K. After comparison, it is found that the material is well preserved in a high temperature environment, indicating that the circular structure has better thermal protection ability. Based on the experiment, the thermal-fluid-solid coupling model is established, and the surface temperature field, deformation field, and stress field are analyzed. Different surface structures are designed, and numerical models of horizontal and vertical splicing components are established. Through numerical simulation, the surface structure is optimized, the surface temperature of the material is reduced, and the gap change trend of the splicing component is displayed. This work has theoretical significance for the application of materials in a high temperature environment and the optimization and improvement of material surface structure.

An Investigation into the Influence of Interrupted Loading in Improving the Stretch-Flangeability of Dual Phase Steel

Materials resistance to edge failure during sheet metal flanging operations is known as stretch-flangeability. It is one of the important concerns in the current automotive sector. Stretch flangeability of sheet metal is estimated by hole expansion test and commonly it is represented by hole expansion ratio (HER). The objective of the present work is to comprehend the hole expansion deformation behavior of DP600 steel. Firstly, finite element analysis was performed to understand the stress state at the edge during the hole expansion test. Thereafter, the effect of stress relaxation was studied by conducting hole expansion tests (HET) in monotonic and interrupted mode. Considerable improvement in the HER was observed. The HER was found to increase with the pre-strain. The combined effect of friction and stress relaxation played a crucial role in delaying the edge failure, resulting in the enhanced HER.

Influence of CaO-based expansive agent on chloride penetration resistance of marine concrete

CaO-based expansive agent (CEA) is a high performance expansive agent, which can well compensate for the shrinkage of concrete. However, due to micro-cracks caused by excessive expansion and poor chemical stability and gelling property of additional Ca(OH)2 (expansion product), durability of marine concrete may deteriorate. Therefore, the application of CEA in marine concrete is controversial. In this study, the autogenous deformation, compressive strength, and chloride penetration resistance of marine concretes containing various dosages of CEA were determined, and the influence mechanism of CEA on the chloride penetration resistance was further explored. The results showed that the addition of CEA increased the expansion deformation, chloride diffusion coefficient, and chloride penetration depth and decreased the compressive strength of marine concrete. In addition, as the dosage of CEA increased, porosity increased and chloride binding capacity decreased. Further discussion indicated that the addition of CEA increased the volume of large capillary pore with diameter between 400 and 5000 nm, and decreased the chloride binding capacity due to the increase in the SO3 content, both of which led to the decrease in chloride penetration resistance of marine concrete. However, when the dosage of CEA was not more than 6%, adding CEA can well compensate for the autogenous shrinkage and improve the crack resistance of marine concrete without a relatively small loss of compressive strength (≤8.7%). In addition, for the marine concretes containing CEA, the chloride diffusion coefficients were very small (<1 × 10-12 m2/s). Therefore, adding no more than 6% CEA, marine concrete had good crack resistance and chloride penetration resistance. Hopefully, the outcomes of this research can provide guidance for the application of CEA in marine concrete.

Dynamic stability of graded graphene reinforced truncated conical shells under both periodic spinning speeds and axial loads considering thermal effects

This paper is concerned with dynamic stability of graded graphene reinforced truncated conical shells under both periodic spinning speeds and axial loads considering thermal effects. The volume fraction of graphene platelets (GPLs) varies continuously along the shell’s thickness direction, which induces the position-dependent effective material properties. Based upon Love’s thin shell theory and Galerkin approach, the equations of motion of the conical shells are derived by considering thermal environment, both time-variable spinning speeds and axial loads. The method of multiple scales is adopted to obtain an analytical solution on the instability boundaries under combination parametric resonances. Then, comprehensive parametric studies are conducted focusing on the instability regions, natural frequencies and critical spinning speeds of the conical shell. The sensitivities of dynamic stabilities on the thermal expansion deformation, thermal conductivity and temperature-dependent material properties are also analyzed. Results show that the conical shell system would be always instability if parametric phase is not equal to integer multiple of π. The GPL parameters, temperature variation, spinning speeds and axial loads have a significant influence on dynamic stability of the conical shell, and thermal conductivity and thermal expansion deformation are nonnegligible in the dynamic stability analysis.

Compressive performance of bamboo sheet twining tube-confined recycled aggregate concrete columns

This paper proposes a new structure for a recycled aggregate concrete (RAC) column confined by a bamboo composite tube (BCT), and the performance of the RAC is further improved by mixing short bamboo strips. An experimental and analytical study of the behavior of bamboo sheet twining tube-confined recycled aggregate concrete (BSTRAC) columns under axial compression is presented. A total of thirty-six axially loaded BSTRAC columns were manufactured to investigate the effects of the number of bamboo sheet layers (BCT thickness) and the volume content of short bamboo strips. The results indicated that the BCT had strong lateral confinement as well as the ability to bear axial loads, which resisted lateral expansion deformation, and the increase in BCT thickness led to an increase in compressive strength and ductility. In addition, the short bamboo strips could improve the compressive strength, ductility and residual bearing capacity of the axially loaded BSTRAC column. Based on the compressive performance of short bamboo strip-reinforced RAC, ten existing FRP-confined concrete models were considered to predict the ultimate stress, ultimate strain and axial stress–strain curves of BSTRAC columns. It can be concluded that some existing models can be used to predict the ultimate stress and ultimate strain of BSTRAC columns accurately; moreover, a few models provide reasonable predictions for the BSTRAC specimens of stress–strain curves.

Parametric Instability of Rotating Functionally Graded Graphene Reinforced Truncated Conical Shells Subjected to Both Mechanical and Thermal Loading Conditions

This article focuses on parametric instability of rotating functionally graded (FG) truncated conical shells reinforced by graphene platelets (GPLs) and subjected to both mechanical and thermal loading conditions. The GPL nanofillers are uniformly dispersed in each concentric conical layer but its weight fraction varies continuously along thickness direction, which induces the position-dependent effective material properties. Based on Love’s thin shell theory and Galerkin approach, the equations of motion for the conical shells are derived with the effects of the periodic axial loads, thermal expansion deformation, rotation-induced initial hoop tension, gyroscopic and centrifugal forces taken into account. Then, the parametric instability under combination parametric resonance for the conical shells is performed by the method of multiple scales, and the analytical solutions of both instability boundaries are obtained. A comprehensive parametric study is conducted which focuses on instability regions and vibration characteristics of the conical shell. Of particular interest in this process is the combined effect of the rotation, dynamic loads and thermal effects on dynamic stability of FG-GPL reinforced truncated conical shells.

The design and investigation of hydrogel-based metamaterials with ultra large negative hygroscopic expansion ratio

ABSTRACT A design strategy for a mechanical metamaterial with large negative hygroscopic expansion (NHE) was proposed in this paper. Different from the reported structures, the present metamaterial is designed by constructing repeated lattice microstructure consisting of curved ligaments incorporating hydrogel active layers and polymer support layers and straight polymer bars. When immersed in the solution environment, the swelling of hydrogel layer of such composite structure induces the reversed bending of the ligament, leading to the overall ultra-large shrink (negative expansion) deformation of the metamaterial. Through the new structural design, large NHE effects can be achieved. The theoretical investigation and finite element analysis (FEA) were conducted to demonstrate the large negative expansion effects of such metamaterial. The results showed that the effective NHE ratio of the metamaterial is dependent of the curvature of the curved ligament and the size of both the ligament and the connecting rod. The ultra-large NHE ratios about −80% for the 2D structure and −90% for the 3D version can be obtained by adopting the structural parameters. The newly designed metamaterials have potential applications in medical and other fields.

Coal Permeability Variation during the Heating Process considering Thermal Expansion and Desorption Shrinkage

In order to explore the influence of coal deformation caused by temperature and desorption on seepage characteristics in the process of heat injection mining of coalbed methane, the permeability test, thermal expansion, and constant temperature adsorption desorption of coal samples under different temperature and stress states were carried out using the high temperature multifunctional triaxial test system, and the influence of thermal expansion and desorption deformation effect on coal permeability in the process of temperature increase is studied. The results show that (1) with the increase of temperature, the sensitivity of coal thermal expansion deformation to temperature decreases gradually. The thermal expansion deformation makes the coal matrix expand, and the seepage channel is squeezed and the permeability decreases. (2) The effect of thermal expansion deformation is related to the porosity of coal. When the porosity of coal is high, the thermal expansion deformation reduces the permeability; on the contrary, the inward expansion of thermal expansion deformation is limited, and the effect on permeability is weakened. (3) The desorption of coal cause matrix shrinkage. The higher the desorption amount, the more obvious the shrinkage and the higher the permeability. Increasing temperature promotes desorption deformation of coal and increases permeability. (4) In the process of increasing temperature, the change of coal permeability is affected by thermal expansion deformation and desorption deformation. With the increase of temperature, when the influence of thermal expansion deformation on coal permeability is dominant, the permeability decreases gradually, and when desorption deformation is dominant on coal permeability, the permeability increases gradually. (5) With the increase of axial pressure, confining pressure, and pore pressure, the decrease of coal porosity is smaller. When the temperature increases, the temperature corresponding to the minimum permeability point is smaller. The research conclusion provides a basis for the technology of heat injection mining coalbed methane.

Blind Source Separation for MT-InSAR Analysis With Structural Health Monitoring Applications

Monitoring large areas of the Earth&#x0027;s surface is possible thanks to the availability of remote sensing data obtained by a large collection of diverse satellites orbiting the Earth. Specifically, multitemporal interferometric synthetic aperture radar (MT-InSAR) techniques supply the structural community with time series of line-of-sight displacements of terrain or structures, such as bridges or buildings, resulting from causes such as thermal expansion, contraction, and terrain deformation. The analysis of the different deformation signals observed is crucial in order to identify the different phenomena that cause the deformation. In this article, we explore the possibility of applying blind source separation algorithms to MT-InSAR, with the aim of developing methods towards automatic identification of different deformation patterns both in buildings and structures. We validate the proposed methodology using both synthetically generated datasets and real MT-InSAR data. We also provide a comparison with other similar methods. Our results demonstrate that InSAR time-series analysis can benefit from the use of the proposed blind source separation approach. Furthermore, the proposed technique is robust to the noise which is usually present in MT-InSAR data. This opens the door for monitoring infrastructure at scale over very large areas, helping to monitor civil infrastructures, and providing relevant insights to asset owners regarding the performance of such structures over time.

Study of Mutual Improvement of Completed Weathered Phyllite and Red Clay Based on Neutralization Effects of Swelling and Shrinkage Deformation

Completely weathered phyllite (CWP) soil is a kind of special soil with high swell potential, while red clay is a special soil with high shrinkage. This means that these two kinds of special soils are usually not suitable for direct use as subgrade fill. To reduce the swell index of the CWP soil and the shrinkage of red clay at the same time, it was proposed to blend the CWP soil with red clay to improve their basic characteristics. A series of swell index tests and dry-wet cycle tests of the blended soils have been carried out at varying blending ratios, compaction coefficients and moisture contents. The test results show that the free swell index of the blended soil decreases with the increase of red clay, moisture content and compaction coefficient, respectively. The fissure density of the blended soil first decreases and then increases with the blending ratio, with the lowest being zero when the blending ratio is ranging from 20% to 40%. Through particle microscopic analysis and elemental composition analysis, it is found that the neutralization effect, the dilution effect of swell minerals, and the partition effect of coarse particles play an important role in restraining expansion and shrinkage deformation of the blended soil. Based on the liquid limit requirement of Chinese Railway Design Code (TB 10001-2016), the optimal blending ratio of red clay has been proposed to be 50%. Compared with the CWP soil, the free load swell index of the blended soil is reduced by 45.0% and the fissure density is reduced by 99.3% compared with that of red clay. Therefore, it is feasible to improve the CWP soil by blending it with red clay at an optimal ratio of 50% by using the neutralization effect of the expansion of CWP and shrinkage of red clay.

Kirigami Deformation Mechanism Using by Multiple Simultaneous Expansions of Bellows-typed Tube

In this study, we designed the multiple semi-bellows type arms driven by pneumatic contoroll, and attempted post-functional operation after pre-fixation in order to utilize the three-dimensional deformation of their actuator functions. In that case, Kirigami structural top plate was fixed, and two-dimensional expansion deformation of the fixed Kirigami top plate synchronized with the bending motion of the arm was examined.

Expansion and Pull-Out Simulation Test of Self-expanding Bond Bolts in Adjacent Rock Bodies with Varied Stiffnesses

To improve the ultimate pullout capacity of bolt structures, developing a self-expanding bond bolt (SEBB) with a High-Performance Calcium-Sulpho-Aluminate (HCSA) expansive agent expounded the mechanism of ultimate pullout capacity improvement. However, the expansion law and ultimate pullout capacity of SEBBs in low-stiffness rock and soil bodies are not clear. This paper uses three steel pipes with varying wall thicknesses to simulate adjacent rock bodies with different radial stiffnesses and tested the evolution law of radial expansion stress and expansion deformation of the anchorage structure. Then, the prediction equation of the expansive stress of SEBBs and the corresponding displacement under initial anisotropic stress is derived, verified the equation's reliability by numerical simulation. Then, carried out a numerical pullout simulation test of SEBBs. The results show that the ultimate pullout capacity of SEBBs is increased by nearly 210% under three kinds of low surrounding rock stiffnesses, and the contribution of Coulomb's friction to the ultimate pullout capacity is more significant than that of the expanded head effect. Finally, established the design equation of the expansive agent dosage based on the strength parameters of the adjacent soft rock and the initial stress to ensure the normal working performance of the self-expanding anchorage structure.

Results of experimental research of wound ballistics of separate types and calibers of modern bullets

There was made the analysis of wound ballistics of modern expansive bullets in comparison with shell bullets on 25 blocks of ballistic plasticine (ROMA PLASTILINA No. 1, Ballistic Testing Backing Material), made in the USA, in which one shot from an AKS-74 automatic firearm and carbine ZBROYAR Z-10 with an optical sight was fired. The bullet speed was the highest in 5.45x39 caliber cartridge with a V-max bullet. – 1185 m/s, low in the bullet caliber cartridge .308 Win with a bullet SP, – 664 m/s. The difference is significant at the level of significance α=0.05. In terms of the size of the entrance hole, the largest is from the bullet of cartridge .308 Win with a bullet SP – 10.0 cm, the smallest - from the bullet "PS" with a steel core 5.45x39 mm, cartridge sample of the year 1974 (7H6) – 1.2 cm. The difference is significant at the level of significance α=0.05. In the expansive bullet of type "V-Max" of shortgun cartridge of caliber 5.45x39 mm, the size of the entrance hole was 9.1 cm, with asterial shape having radial gaps and turned edges of ballistic plasticine on the outside. All cartridges with expansive bullets did not have an exit hole after the shot. The dimensions of the formed residual cavity were the largest after firing with .308 Win caliber cartridge with a bullet SP – 25.0x5.0 cm., the smallest – bullet of a military caliber cartridge of 5.45x39 mm (7H6) – 6.0x4.0 cm. The difference is significant at significance level α=0.05. The shape and character of the residual cavity in ballistic plasticine was significant for all expansive bullets, in contrast to the bullet of a military cartridge 5.45x39 mm (7H6), where no such changes are detected. The considerable signs of expansion properties and deformation of the bullet in the form of a "flower of death" were identified in the bullet of caliber cartridge .308 Win with a bullet SP, other bullets with expansive properties showed significant fragmentation, with the location of fragments both in the residual cavity and outside its borders at different distances. Expansive bullets differ significantly at the level of significance α=0.05. The low flight speed of bullets (m/s) of .308 Win caliber cartridges with bullets BTHP and SP is due to their structure, weight, and caliber. Bullet of type V-max with cartridge 5.45x39 mm has the highest speed – 1185 m/s, and due to its design has significant expansive properties. Common to expansive bullets is a entrance hole, the blind nature of the lesion with the presence of a large residual cavity, which is due to kinetic energy return 114.37 E, J/mm2 inside the object of lesion. Fragmentation of expansion bullets occurs inside an object with fragments located at different distances. A .308 Win caliber cartridge with SP bullet causes deformation of s bullet by the type of "death flower" causing significant damage.

Deformation Mechanism of the Coal ahead of Fully Mechanized Caving Face under High-Intensity Mining Condition

In order to study the coal deformation and failure mechanism in fully mechanized caving face under the high-intensity mining, based on the equivalent mechanical model of transversely isotropic cylindrical coal with fractures, the equivalent equations for axial, radial, and volume strains of coal sample loaded in linear elastic and plastic stages were derived in this paper. The equivalent mechanical model shows good reliability through the conventional triaxial experiment. Taking the N1206 workface in Yuwu coal mine of Luan group as the example, we have simulated the stress concentration factor of the coal body ahead of the working face with FLAC and divided three regions according to stress distribution in coal mining. Mathematical equations were derived to express the horizontal and vertical stress, which provide theoretical guidance of the stress paths in triaxial experiment about real mining stress environment simulation. Experimental results show that the volume strain’s value is about 0.4% in the coal mass deformation progress of axial compression increasing slowly area. In axial compression increasing rapidly area, the volume strain’s value varies from 0.41% to 0.27%, and the radical strain changes from compression deformation to expansion deformation gradually. The volume strain of coal sample increases sharply in axial compression releasing rapidly area; meanwhile, there are good linear relationships between Poisson’s ratio and axial strain and radial strain.