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To prevent the weathering deterioration of stone building heritages in Putuo Zongcheng Temple, the fluorinated acrylate copolymer was prepared with methyl methacrylate, n-butyl acrylate, and 2,2,3,4,4,4-hexafluorobutyl methacrylate as monomers. The structure and surface morphology of the copolymer were described by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The antiaging of the copolymer was studied by the ultraviolet aging test; the contact angle and imbibition spontaneous tests were performed to estimate the wettability alteration of the copolymer emulsion. Results show that the fluorinated copolymer with 32.54 % HFMA content possesses optimal aging resistance and superb hydrophobicity. The contact angles of coated samples range from 96.90° to 125.80°. Considering the influence of water on rock weathering, the fluorinated copolymer coating is a potential method to avoid the degrading of stone heritages.

It is essential to evaluate the blasting-enhanced permeability (BEP) feasibility of a low-permeability sandstone-type uranium deposit. In this work, the mineral composition, reservoir physical properties and rock mechanical properties of samples from sandstone-type uranium deposits were first measured. Then, the reformability evaluation method was established by the analytic hierarchy process-entropy weight method (AHP-EWM) and the fuzzy mathematics method. Finally, evaluation results were verified by the split Hopkinson Pressure Bar (SHPB) experiment and permeability test. Results show that medium sandstone, argillaceous sandstone and siltstone exhibit excellent reformability, followed by coarse sandstone and fine sandstone, while the reformability of sandy mudstone is poor and is not able to accept BEP reservoir stimulation. The permeability improvement and the distribution of damage fractures before and after the SHPB experiment confirm the correctness of evaluation results. This research provides a reformability evaluation method for the BEP of the low-permeability sandstone-type uranium deposit, which contributes to the selection of the appropriate regional and stratigraphic horizon of the BEP and the enhanced ISL of the low-permeability sandstone-type uranium deposit.

AbstractStudy of strain localization in geomaterials generally consists of two aspects, the pre-localization regime and the post-localization regime. The former refers to the onset and the orientation of the shear band, which corresponds to the bifurcation theory. The latter deals with the width and the evolution of the shear band. The purpose of this paper is to make a full-range analysis of the shear band in structural level. By comparing the bifurcation conditions in classical continuum an analogical bifurcation condition in micropolar theory is defined. The factors which may affect the shear band orientation in the numerical modeling process are emphasized, and a basic principle of the geometric modeling is concluded. Furthermore, the existing shear band width measurement methods are summarized, and some other more effective methods considering the singularity of the discontinuous surface is suggested. At the last, the ratio between the node distance of the element and the internal length less than 5 is suggested as reasonable choice.

Straw checkerboard sand barriers with a porous structure that consists of a pervious upper portion and a dense lower portion are widely used to achieve great sand control effect. Considering this, and resolving the serious earth surface undercutting problem after HDPE sandbreak net checkboard barriers setting, the authors used HDPE (high-density polyethylene) materials to prepare new sandbreak materials with a similar porous structure. Through wind tunnel simulations and field sand control monitoring, we compared the sand control effect of three HDPE sandbreak nets with different porosity structure. Compared to the sandbreak net with uniform porosity structure, the three types of HDPE sandbreak nets with different porosity structure had poorer effect on reducing sand transport rates, but had longer effective protection distance before sandbreak nets at low wind velocity conditions (<12 m/s), longer effective protection distance at high wind velocity (>14 m/s) and longer effective protection distance between sandbreak nets at all experimental wind velocity conditions. Wind and sand control effect characteristics of HDPE sandbreak nets with different porosity structure provide an ideal material on semi-buried checkerboard sand barriers for sand stabilization. By contrast, uniform-type sandbreak nets are used as materials on high upright sand fences for sand blocking. These HDPE sandbreak nets can be used to replace traditional sandbreak materials and have a very high potential for widespread and popular application in aeolian sand disaster control.

To understand and evaluate the CO2injectivity in different coal seams, low-, middle-, and high-rank coals from Shanxi Province of China were collected to conduct CO2adsorption/desorption, induced swelling/shrinkage, and permeability experiments. Results show that the adsorption/desorption amount, swelling/shrinkage deformation, and permeability depend on the coal rank. The CO2adsorption/desorption amount of high-rank coal is the largest, followed by middle-rank coal, and that of low-rank coal is the smallest. The swelling/shrinkage strain and initial permeability of coals follow the sequence middle-rank coal > low-rank coal > high-rank coal. The percentage reductions of permeability of low-rank coal, middle-rank coal, and high-rank coal are 57.46, 48.50, and 71.17% when CO2adsorption reaches the equilibrium state, indicating that the permeability of high-rank coal is more sensitive for the CO2adsorption swelling. The swelling and shrinkage deformation presents obvious three-dimensional anisotropic characteristics; the deformation in the vertical bedding plane direction (VBD) is the maximum, the second is that in the parallel face cleat direction (PFD), and the deformation in the parallel butt cleat direction (PBD) is the maximum. The developmental characteristics of cleats and the distribution of macerals in coal contribute largely to the anisotropic deformation of coal induced by CO2adsorption–desorption. The permeability of coal shows a U-shaped change trend of first decreasing and then increasing after CO2adsorption because the permeability of coal is first dominated by the CO2adsorption swelling and then is dominated by the reduction of effective stress. The swelling behavior and permeability attenuation of coal seams after CO2injection are unavoidable; adopting the reservoir stimulation methods to produce more complex fracture networks is the key to improving CO2injectivity. Combining the reservoir stimulation methods with CO2-ECBM technology may be an important development direction of the CCUS in coal seams.

The Lanzhou-Xinjiang high-speed railway (HSR) traverses areas of the Gobi Desert where extremely strong winds are frequent. These strong winds cause sand/gravel hazards, an unaddressed issue that often seriously compromises the safe operation of the HSR. This paper studies the mechanisms leading to wind-blown sand hazards and the outcomes of sand control projects in these areas. The main findings are as follows: (1) Cold northern airflows over the Tian Shan mountain range are accelerated by the wind tunnels and downslope effect as they pass over complex terrain comprising passes, gullies, and proluvial fans. Consequently, the wind intensity often increases two- to threefold, creating frequent high-speed winds that lead to severe sand damage along the HSR. (2) In the Gobi areas with extremely strong winds, sand grains can be lifted as high as 9 m from the ground into the air, far higher than in other areas of the desert. The sand transport rate decreases exponentially with increasing height. Both wind speed and particle size determine saltation height. Coarser particles and stronger winds provide the particles with a higher kinetic energy as they collide with the ground. In the wind zones of Baili and Yandun, the analysed study areas, the saltation layer height of wind-blown sand/gravel exceeds 3 and 2 m, respectively. (3) Based on the above findings, recently emerging sand control materials, suitable for the areas of interest, were screened and developed. Furthermore, under the proposed principle of ‘supplementing blocking with trapping’, a comprehensive sand control measure was established, featuring sand-blocking belts comprised of multiple rows, and high, vertical sand-trapping installations with a large grids size. The installed system showed a high efficacy, reducing sand transport rate by 87.87% and significantly decreasing the deposition of sand along a trial section of the HSR.

Coal pores are the locations of coalbed methane occurrence and enrichment and the main storage space targeted in CO2sequestration. The systematic investigation of the coal pore structure and its development is of great significance to provide insights into coalbed methane generation, coal mine gas outburst mechanisms, and coal seam CO2sequestration. In this study, coal pore testing technologies and methods, pore classification methods, and coal pore structure characteristics and their main control factors were systematically investigated and summarized. The results show that direct test methods, indirect fluid injection test methods, and X-ray and spectroscopic methods have been used for the quantitative characterization of the pore structure. However, each testing method has limitations. Therefore, a comprehensive method for the quantitative characterization of the full-scale pore structure must be developed, especially for the accurate quantitative characterization of closed pores in coal. The in situmeasurement of pores in coal is one of the future research trends. Classification methods of pores in coal mainly include the classification of the genetic pore type, pore size, and pore morphology. Metamorphism, tectonic deformation, and macerals are the main internal factors affecting the pore distribution in coal. The effect of tectonic deformation on the macromolecular structure and micro- and ultramicropores of coal must be further studied. In addition, molecular mechanics simulations, molecular dynamics simulations, and quantum chemistry calculations of the dynamic response of the macromolecular structure and micro- and ultramicropores during gas adsorption and desorption must be carried out.

CO2enhanced coalbed methane recovery (CO2-ECBM) has been confirmed as an effective technology to improve coalbed methane (CBM) production; however, the injected CO2and the reservoir water can react with the caprock of the coal seam, which changes its internal structure and increases the risk of CO2leakage. To clarify the CO2–water–rock reaction process and the structural responses of the caprock, the roof mudstone samples of coal seams from Qinshui Basin were first selected to conduct the geochemical reaction experiment; then, scanning electron microscopy (SEM), N2adsorption, and mercury intrusion porosimetry were adopted to monitor the multiscale structure alteration of the samples. The results show that the rock sample has progressively deteriorated during the CO2–water–rock reaction process, and this effect is aggravated with the increase of the reaction time. The dissolution process consists of three stages: (1) lots of isolated and shallow holes are developed; (2) holes are connected and formed to the dissolution grooves; (3) dissolution grooves are widened, and the dissolution zone is expanded until all the soluble minerals immerse into the reaction solution. The pore volume (PV) and specific surface area (SSA) of small pores are reduced, while those of large pores are increased, which can be attributed to the pore-blocking effect caused by clay mineral swelling and mineral precipitation and the pore-enlarging effect caused by mineral dissolution, respectively. Additionally, the ScCO2–water–rock reaction varies the pore structure distribution and makes the PV distribution more heterogeneous and the SSA distribution more homogeneous. The changes in the internal structure of the roof mudstone promote gas diffusion and seepage, which may increase the potential threat of CO2leakage during the long-term CO2-ECBM process to a certain degree. This study will provide an essential basis for the investigation and evaluation of the security of CO2-ECBM in Qinshui Basin, China.

CO2injection to enhance coalbed methane (CO2-ECBM) production is a promising technology for realizing the efficient exploitation of new energy resource, but its effect is cooperatively affected by miscellaneous influencing factors. To elucidate the mechanism and increase the efficiency of the displacement of CH4by CO2, CO2flooding experiments under the influence of the injection pressure, confining pressure, and temperature were conducted. The results show that an increase in the injection pressure enlarges the pore-fracture network of the coal matrix and promotes its gas adsorption ability and seepage capacity, while an increase in the confining pressure compresses the coal body and reduces the adsorption capacity and permeability. Increasing the temperature enhances kinetic energy and induces the thermal swelling effect, which disfavors the adsorption and seepage processes. The CO2adsorption capacity is larger than the CH4adsorption capacity due to the higher adsorption affinity of CO2, but the CO2permeability is lower than the CH4permeability due to the severe adsorption swelling effect. The CO2flooding process is characterized by three parameters (equal percentage displacement time, displacement rate, and displacement efficiency) and can be divided into the CO2driving stage, replacement and displacement stage, and equilibrium stage. The injection pressure and temperature decrease the displacement time and increase the displacement rate and displacement efficiency, while confining pressure shows the opposite trends. Multifactor interaction models of the displacement efficiency of coal seams at various buried depths were established and demonstrated to appropriately predict the displacement efficiency of CO2-ECBM in deep coal seams. The displacement efficiency is controlled by the reservoir performance, geological characteristics, and CO2injection technology. The selection of a high-permeability coal reservoir and coal seams with an appropriate buried depth and the development of a reasonable injection plan are suggested for the implementation of CO2-ECBM extraction.

Aerial photographs and 3-D laser scans of a 90-m high star dune at the Crescent Moon Spring scenic spot in Dunhuang, China, are used to investigate the changes in dune morphology on timescales from months to decades. The result revealed that relative-equilibrium airflow strength in three wind directions of northeast, west and south was an important condition for the stability of star dunes with limited migration. Transverse and longitudinal airflows exerted a crucial impact on variation processes of star dune morphology. Controlled by transverse airflows, the easterly winds, the east side was dominated by wind erosion; and strong deposition occurred on the south-south-east arm with a maximum deposition rate of 0.44 m/a in the 46-a monitoring period, causing the east side becoming steep and high. Controlled by longitudinal airflows, the westerly winds, the west-north-west side was mainly eroded and the north arm migrated from west to east with a rate of 0.30 m/a, causing the dune slope becoming gentle and elongate. The local air circulation (southerly winds) exerted a significant impact on the development process of the star dune. Due to the influence of human activities, the south side present surface processes from a concave profile to a convex profile in 46 a, which is a potential threat to the Crescent Moon Spring. The results indicate that rehabilitating the airflow field at most is a crucial strategy to the protection of Crescent Moon Spring from burial. Opening up the passage of easterly, westerly and southerly winds through intermediately cutting the protection forest, demolishing the enclosed wall and changing the pavilion into a porous pattern have been suggested to protect the Crescent Moon Spring from burial.

Groundwater is one of the important factors controling the accumulation and exploitation of coal measures gas. In this work, a water source identification method based on hydrochemistry, stable isotope, 129I and 14C dating is first established; then, the source, age, and evolution of coal measures water in the Central-South Qinshui Basin are clarified. The results reveal that the hydrogeological environment of coal measures water in Carboniferous-Permian is between semiclosed and open, with free water exchanging. The coal measures water in the Guxian and Shizhuangnan blocks are Ca-HCO3and Na-HCO3types, respectively, while the closed coefficients are 1.77 and 322.75, respectively. Therefore, the water is attributed to river water or shallow groundwater in the Guxian block and deep groundwater in the Shizhuangnan block. The age of coal measures water is 1.51–20.61 Ma, which indicates that the water in coal measures at the present stage is a mixture of a little paleo sedimentary water and massive modern meteoric water and that the modern meteoric water recharge lasted until 1950. The above achievements deepen the understanding of the coal measures reservoir type and also guide the optimal selection and co-exploration and -exploitation of coal measures gas.

The changes of anisotropic adsorption–swelling and permeability with injecting CO2in coal influence the CO2injectivity during CO2-ECBM or CGS (ECBM = enhancing coal bed methane; CGS = CO2geological sequestration). To strengthen the understanding of this issue, two special-made cubic coal samples were adopted to test the porosity, swelling, and permeability in parallel face cleat and bedding plane direction, parallel butt cleat and bedding plane direction, and vertical bedding plane direction. To quantitatively characterize the anisotropic porosity, anisotropic swelling, and anisotropic permeability, an anisotropy index was introduced in this work. The results show that porosity anisotropy reflects the pore connectivity in different directions, which fall in the order of parallel face cleat and bedding plane direction > parallel butt cleat and bedding plane direction >vertical bedding plane direction. The porosity varieties can be owed to the compaction effect, thermal evolution effect, banded structure, and cleat distribution in coal seams. The maximum swelling ratios of the vertical bedding plane direction to the parallel bedding plane direction are 2.30 in sample 1 and 1.89 in sample 2. However, the ratios of parallel face cleat to parallel butt cleat are 1.28 in sample 1 and 1.30 in sample 2. The inhomogeneity of matter composition in the vertical bedding direction and the difference of cleat distribution in various coal bands mainly cause the anisotropic swelling. Both injecting CO2in coal and raising its temperature increase the anisotropy swelling index, but the effect of thermal swelling is quite weak. Adsorbing CO2especially for supercritical CO2will enhance the permeability anisotropy of coal. This is because the low-permeability cleat possesses higher permeability adsorption sensitivity and the bedding plane fracture with higher permeability instead does not produce a pronounced permeability drop because of its lower permeability adsorption sensitivity. Cleats that are easily affected by adsorption–swelling always serve as throats between fractures and the coal matrix in a high-anisotropic coal, which will restrain CO2flow in coal pores. Accordingly, cleat seepage and corresponding potential enhanced permeability measures deserve being paid enough attention to in future research. This work clarifies the understanding and offers some implications for CO2injecting into coal seams from the perspective of anistropic properties of coal.

The Singing Sand Mountain and Crescent Spring Scenic Spot in Dunhuang, Northwest China is a world-renowned desert attraction that is also an integral component of the Dunhuang UNESCO Global Geopark. This scenic area underwent a 30-year transformation, i.e., from a severe sand risk with spring water threatened by sand burial due to dune deformation, to restoration of the original sand flow field and mitigation of the sand burial problem. The current paper summarizes the research on the intensive monitoring of the dynamic change of star dunes near the spring, observation of wind and sand flow movement, and then restoring the harmonic vibration of the sand particles (singing sand) that were previously silenced. The existing and prospective impacts of anthropogenic and natural forces on the deformation of the sand dunes are investigated by integrated methods, guiding the implementation of mitigating measures with significant ameliorative effects. Contrast to common sand control practices that aim to reduce wind speed and stop blown sands, our research highlights the importance of maintaining the natural wind flow field in stabilizing surrounding dunes. These mitigation measures consist of removing excessive vegetation and newly constructed buildings to recover the original wind flow field and sand transport activity. Such research and mitigation efforts ensure the scientific protection and restoration of the special desert landform, and contribute to the mutual enhancement of the conservation and exploitation of this desert scenic spot and similar sites.

The Crescent Moon Spring is a precious natural heritage. However, the dynamic characteristics of megadunes around the Crescent Moon Spring are not well known. This paper quantitatively studied the characteristics and changes of megadunes around the Crescent Moon Spring by interpreting aerial photographs taken in 1985 and 2004 and analysing the dune crestlines and the wind data collected from 2011 to 2012. Results revealed that pyramid dunes were formed by a complex wind regime. The Crescent Moon Spring was not buried by shifting sands because of the stable wind regime and relative stability of pyramid dunes. The crestlines of the dunes around the spring moved northward between 1985 and 2004. The south-facing slip faces were also exposed to wind erosion, whereas the other faces were under deposition, thus indicating that the southerly wind was relatively enhanced. Limiting the scale of tall windbreaks and architectures in the Dunhuang oasis at the north of the spring was necessary to maintain the dynamic equilibrium of the wind regime and sand transport.

Disturbance in wind regime and sand erosion deposition balance may lead to burial and eventual vanishing of a site. This study conducted 3D computational fluid dynamics (CFD) simulations to evaluate the effect of a proposed city design on the wind environment of the Crescent Spring, a downwind natural heritage site located in Dunhuang, Northwestern China. Satellite terrain data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Digital Elevation Model (DEM) were used to construct the solid surface model. Steady-state Reynolds Averaged Navier-Stokes equations (RANS) with shear stress transport (SST) k-ω turbulence model were then applied to solve the flow field problems. Land-use changes were modeled implicitly by dividing the underlying surface into different areas and by applying corresponding aerodynamic roughness lengths. Simulations were performed by using cases with different city areas and building heights. Results show that the selected model could capture the surface roughness changes and could adjust wind profile over a large area. Wind profiles varied over the greenfield to the north and over the Gobi land to the east of the spring. Therefore, different wind speed reduction effects were observed from various city construction scenarios. The current city design would lead to about 2 m/s of wind speed reduction at the downwind city edge and about 1 m/s of wind speed reduction at the north of the spring at 35-m height. Reducing the city height in the north greenfield area could efficiently eliminate the negative effects of wind spee. By contrast, restricting the city area worked better in the eastern Gobi area compared with other parts of the study area. Wind speed reduction in areas near the spring could be limited to 0.1 m/s by combining these two abatement strategies. The CFD method could be applied to simulate the wind environment affected by other land-use changes over a large terrain.

The Kumtagh Desert, the last desert in China to be explored, contains a distribution of feathery dunes, a type of complex linear dune composited by linear dunes and lingoid zibars. A debate about the existence, underlying relief and formation process of these dunes has been ongoing since 1974. The authors use ground‐penetrating radar (GPR) images across dunes and interdune areas to better understand the shallow underlying relief and sedimentary structure of the dunes in the Kumtagh Desert. The results are compared with adjacent outcrops and exposures in an excavated trench. No evidence was found for underlying relief, such as yardangs, consistent with the trend and distribution of linear dune ridges that might have controlled the orientation of the dune. However, outcrop observation and remote sensing investigation indicate little gravel bar topography across or along the dunes. Lingoid zibars are common in interdune corridors. Sedimentary structures imaged by GPR in the zibar dunes indicate low‐angle strata dipping towards the SW, indicative of sand accumulation on the leeside of the lingoid zibar with dune migration towards the SW. Strata within the linear dunes are less well‐resolved but are interpreted to indicate a bimodal dip that has been recognized in previous studies of linear dunes.

Abstract: Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km2 and consist of crescent sand ridges and interridge tongue-shaped dunes. Differences in grain size, mineral composition and albedo between crescent sand ridges and tongue-shaped dunes, and between windward and leeward slopes of tongue-shaped dunes, result in their feathery appearance in aerial and satellite imagery. Measurements of the sand drift potential in the region show that the sand-moving wind for feathered sand ridges can be divided into three sectors; i.e. north-northeasterly, easterly and east-northeasterly sectors roughly corresponding to the southeast, northwest and southwest slip faces. Our findings suggests that the crescent sand ridges resulting from the connection of barchan dunes along the prevailing wind direction are longitudinal dune ridges rather than transverse ones. Tongue-shaped dunes and quasi-dune shapes have obvious distinctions and are new transverse dune types. According to McKee’s dune shape classification, the feathered sand ridges are not a deformation dune type but a complex one. According to Wu’s dune morphological and genetic classification, they are not dune ridges or compound dune ridges that form under the action of unidirectional winds or two winds intersecting at an acute angle, but are complex dune ridges that form under the action of three winds intersecting at an acute angle.

Granule ripples are widespread on Earth and are a fundamental component of dryland sedimentary systems, but the relationship between their wavelength and surface particle size is unclear; in addition, their sedimentary bedding and granule ripple development are incompletely understood. In this study, we examined the relationship between granule ripple development, morphology, and the surface grain‐size distribution. We measured the morphology and particle‐size distribution of granule ripples in China's Kumtagh Desert, and found an exponential relationship between ripple wavelength and average crest particle size, which contradicts previous results. We hypothesize the ripples resulted from creep of coarse particles caused by saltation impacts, accompanied by decreasing bed elevation, leading to crest migration and increased crest height. The size composition and wind regime determined the movement mode of particles, which controlled ripple development and size, but dry–wet and freeze–thaw cycles also contributed. We established a new conceptual model for the development of large granule ripples. Sand ripples and small granule ripples develop similarly, but large ripples did not form from merger of smaller ripples. We report for the first time that particles between 2.3 and 4.7 mm in diameter were missing in the ripple crests (confirmed in wind tunnel experiments). This gap affects the particle movement mode. Since the threshold wind speed for particle saltation at 4.7 mm approaches the regional maximum wind speed, quantifying the missing particles may permit prediction of regional maximum wind speeds, and has practical significance for identifying wind conditions elsewhere, including the surface of Mars. Granule ripple landforms develop under strong winds. Understanding their dynamics and characteristics better would reveal how near‐surface wind and sediment characteristics control sediment transport and the development and evolution of Aeolian landforms. We investigated granule ripple morphological characteristics and their range of particle sizes in China's Kumtagh Desert. We found a new relationship between particle size and ripple wavelength, and demonstrated that the largest ripples didn't form from merger of smaller ripples. Our results reveal a new conceptual model for large granule ripple development. We report for the first time that particle sizes from 2.3 to 4.7 mm were missing in the ripple crests (confirmed in a wind tunnel). The particles larger than 4.7 mm can only roll along the surface, whereas particles smaller than 2.3 mm can both roll and jump. The size gap represents a transition between the two movement modes. The particle movement mode is determined by the particle size and wind regime, which control granule ripple development and size, but dry–wet and freeze–thaw cycles also contributed. This phenomenon was missed in previous research, but may let us predict regional maximum wind speeds without needing to monitor these speeds in the field. We found a new quantitative relationship between granule‐ripple wavelength and crest particle sizeOur results represent a new conceptual model for large granule ripple developmentParticles of a certain size were missing from the ripple crests, and this provides a new method for quantifying maximum wind speeds We found a new quantitative relationship between granule‐ripple wavelength and crest particle size Our results represent a new conceptual model for large granule ripple development Particles of a certain size were missing from the ripple crests, and this provides a new method for quantifying maximum wind speeds

To carry out an in-depth study of the macromolecular differences of vitrinite and inertinite with metamorphism degree, ultimate analysis, Fourier transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy, and X-ray diffraction (XRD) were performed on coal macerals by density gradient centrifugation (DGC). Results show that carbon gradually increases rapidly, hydrogen and oxygen decrease significantly, sulfur gradually decreases, and the change of nitrogen is not obvious with coal rank. Functional groups (ether, carbonyl, hydroxyl, and methylene) gradually fall off with Ro,max, and the molecular chains are reconnected to larger macromolecular chains, which eventually increases the maturity and aromaticity of vitrinite and inertinite. The shedding of aliphatic side chains and oxygen functional groups makes the arrangement of coal macromolecules more orderly, the lattice defects of C atom less, and the structure closer to graphitization, which finally show as the decrease of d002and the increase of Laand Lc. The aromatic structure parameters (fa–F, I, DOC) of vitrinite are lower than those of inertinite, which indicates that the maturity and aromaticity degree of vitrinite are lower than those of inertinite; the aliphatic side chains of vitrinite are larger than those of inertinite, which makes the hydrocarbon generation potential of vitrinite higher than that of inertinite. Vitrinite has more functional groups and complex structure than inertinite, which makes its C atom lattice defects larger and graphitization degree lower than inertinite. Finally, the heterogeneity of macromolecular structure of vitrinite is larger than that of inertinite. This study can provide the basis for macromolecular structure evolution and molecular modeling of coal macerals.