Deep Underground Science and Engineering最新文献

{"title":"Dynamic evolution in mechanical characteristics of complex supporting structures during large section tunnel construction","authors":"Hua Jiang,&nbsp;Jianhua Mu,&nbsp;Jinxun Zhang,&nbsp;Yusheng Jiang,&nbsp;Chongyang Liu,&nbsp;Xiaoyan Zhang","doi":"10.1002/dug2.12027","DOIUrl":"10.1002/dug2.12027","url":null,"abstract":"<p>The shallow tunnelling method (STM) often uses temporary supports to divide large section tunnels into several closed or semiclosed sections so as to share the upper load. The complex support system composed of primary and temporary supports can ensure safety during tunnel construction. Based on the large section tunnel of Beijing Subway Line 12, the mechanical characteristics of support system by the double-side-drift method (DSDM) during excavation and demolition were analyzed through numerical simulation and monitoring. The study showed that the middle cave excavation was the most critical stage of the DSDM, during which the load on the supporting structure increased significantly. The temporary vertical support bore most of the new load during middle cave excavation. During the demolition stage, the load was redistributed, which caused arch settlement and section convergence. The removal of the temporary vertical support exerted the greatest impact in this process. The lateral temporary inverted arch changed from axial compression to axial tension after the middle and lower caves were excavated. Based on the mechanical characteristics of the support system, some engineering suggestions were proposed for large section tunnel construction. These research results can provide reference for the design and construction of similar large section tunnels.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 2","pages":"183-201"},"PeriodicalIF":0.0,"publicationDate":"2022-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80501320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Potential triggers for large earthquakes in open-pit mines: A case study from Kuzbass, Siberia","authors":"Gevorg Kocharyan,&nbsp;Chengzhi Qi,&nbsp;Svetlana Kishkina,&nbsp;Vladimir Kulikov","doi":"10.1002/dug2.12028","DOIUrl":"10.1002/dug2.12028","url":null,"abstract":"<p>The extraction and movement of rock during mining operations is considered a possible trigger for slip along the fault. In this study, possible anthropogenic causes were analyzed for triggering the earthquake with the local magnitude of <i>M</i>_L = 6.1 (at a depth of 4 km just beneath the quarry), in the vicinity of the large coal open-pit mine in Russia. This event was the largest earthquake associated with a quarry (an open pit). A sufficiently deep occurrence of the source testified that seismic vibrations were produced in a dynamic slip along a preexisting and prestressed tectonic fault. Analytical calculations were conducted of increments of normal and shear stresses at fault planes with several dip angles at depths corresponding to the probable location of the hypocenter of the Bachat earthquake. As the results show, long-term rock excavations bring a prestressed thrust fault closer to the ultimate Coulomb strength, and stress variations at those depths may suffice to initiate a movement along the fault. By measuring seismic vibrations at different quarries and mines in Russia, the dynamic effect at the supposed depth of the source occurrence could be reliably estimated. As is shown, the ultimate anticipated dynamic deformations are noticeably lower than corresponding values produced by seismic waves of distant earthquakes in the case when the effects of dynamic triggering were observed. Accordingly, the seismic effect of explosions cannot trigger a large earthquake with deep source occurrence. Operations in open-pit mines can only bring forward the moment of an earthquake at a potentially seismogenic fault. At the same time, the numerical calculations reveal that a branching network of underground tunnels located at several horizons can noticeably reduce the effective shear modulus of the host rock. This effect can even provoke a dynamic movement at a previously aseismic fault.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 2","pages":"101-115"},"PeriodicalIF":0.0,"publicationDate":"2022-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73746810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Grouting theories and technologies for the reinforcement of fractured rocks surrounding deep roadways","authors":"Hongpu Kang,&nbsp;Wenzhou Li,&nbsp;Fuqiang Gao,&nbsp;Jianwei Yang","doi":"10.1002/dug2.12026","DOIUrl":"https://doi.org/10.1002/dug2.12026","url":null,"abstract":"<p>Grouting is an effective method to improve the integrity and stability of fractured rocks that surround deep roadways. After years of research and practice, various theories and a complete set of grouting technologies for deep roadways with fractured rocks have been developed and are widely applied in Chinese coal mining production. This paper systematically summarizes and analyzes the research results concerning the theory, design, materials, processes, and equipment for the grouting and reinforcement of fractured rocks surrounding deep roadways. Specifically, in terms of grouting methods, pregrouting, grouting-while-excavation, and postgrouting methods are explored; in terms of grouting theory, backfill grouting, compaction grouting, infiltration grouting, and fracture grouting theories are studied. In addition, this paper also studies grouting borehole arrangement, water-cement ratio, grouting pressure, grouting volume, grout diffusion radius, and other grouting parameters and their determination methods. On this basis, this paper explores the physical and mechanical properties of organic and organic-inorganic composite grouting materials, and assess grouting reinforcement quality testing methods and instruments. Taken as the field cases, the application of pregrouting in front of heading faces, grouting-while-excavation, and postgrouting in the Kouzidong coal mine are then introduced, and the effects of the grouting reinforcements are evaluated. This paper proposes a development direction for grouting technology based on problems existing in the grouting reinforcement of fractured rocks surrounding deep roadways.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"2 1","pages":"2-19"},"PeriodicalIF":0.0,"publicationDate":"2022-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50151259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deformation characteristics and novel strain criteria of strainbursts induced by low-frequency cyclic disturbance","authors":"Lihua Hu,&nbsp;Minghe Ju,&nbsp;Peng Zhao,&nbsp;Xiaozhao Li","doi":"10.1002/dug2.12029","DOIUrl":"https://doi.org/10.1002/dug2.12029","url":null,"abstract":"<p>Strainbursts induced by cyclic disturbance with low frequency (termed as cyclic-induced strainbursts) are major dynamic disasters during deep excavation and mining. There is currently no quantitative criterion available for the prediction of such disastrous events. In this study, based on true triaxial experiments, we analyzed the deformation characteristics, established two novel strain criteria for the cyclic-induced strainbursts, and explained the physical meaning of these criteria. Characteristic strains for the cyclic-induced strainbursts were defined, including the control strain <i>ε</i>_ctr, the strain caused by the combined dynamic and static loading <i>ε</i>_sd, and the ultimate strain <i>ε</i>_u after strainbursts. As indicated by the results, the deformation evolution of the cyclic-induced strainbursts shows remarkable fatigue characteristics, which resemble that of rock subjected to cyclic loading and unloading. In other words, there are three stages during deformation evolution, namely, initial rapid growth, uniform velocity growth after several periods of disturbance, and sudden sharp growth preceding the burst. The ultimate strain <i>ε</i>_u is insensitive to the tangential static stress and disturbance amplitude, but it changes nonlinearly with disturbance frequency. From the perspective of deformation, the occurrence of a cyclic-induced strainburst is controlled by the control strain <i>ε</i>_ctr. Thus, a control strain criterion is proposed; that is, when the stain <i>ε</i>_sd is larger than the control strain <i>ε</i>_ctr, a strainburst will be induced by cyclic disturbance. Moreover, based on the statistical results, a strain ratio criterion is proposed; that is, when the strain ratio <i>ε</i>_sd/<i>ε</i>_u is greater than 30%, a cyclic-induced strainburst will be induced.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"2 1","pages":"52-60"},"PeriodicalIF":0.0,"publicationDate":"2022-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50132100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of joints on microwave fracturing of the Bukit Timah granite using an open-ended antenna","authors":"Zhongjun Ma,&nbsp;Yanlong Zheng,&nbsp;Lei He,&nbsp;Jianchun Li","doi":"10.1002/dug2.12024","DOIUrl":"10.1002/dug2.12024","url":null,"abstract":"<p>Microwave fracturing of rocks before mechanical breakage could improve the performance of mechanical excavators and reduce environmental impacts. Previous research focused on the microwave fracturing of intact rock blocks. By using an open-ended antenna, this paper investigates the effect of pre-existing joints on the microwave fracturing of the Singapore Bukit Timah granite blocks. The results show that the specimens are weakened in the manners of cracking, spalling, melting, or a combination of them. The crack number and the total crack length produced by microwave treatment of jointed rock blocks are slightly smaller than those in the intact rock blocks. The interaction between joints and microwave-induced cracks can be summarized into the following four patterns: (1) microwave-induced cracks become arrested so that the crack propagation is terminated; (2) microwave-induced cracks penetrate the joints and continue to propagate; (3) microwave-induced cracks become deflected along the joints; and (4) microwave-induced cracks propagate forward following the joints. The smaller the approach angle between the microwave-induced crack and the pre-existing joint is, the more microwave-induced cracks tend to be arrested at the joint. Increasing the approach angle between the microwave-induced crack and the joint can increase the chance of microwave-induced crack penetrating the joint. The results also show that the smaller the distance is between the microwave radiation point and the joint, the easier it is for microwave-induced cracks to penetrate the joints; otherwise, the microwave-induced crack is more likely to be arrested at the pre-existing joint.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 2","pages":"138-147"},"PeriodicalIF":0.0,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81040299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coal rock image recognition method based on improved CLBP and receptive field theory","authors":"Chuanmeng Sun,&nbsp;Ruijia Xu,&nbsp;Chong Wang,&nbsp;Tiehua Ma,&nbsp;Jiaxin Chen","doi":"10.1002/dug2.12023","DOIUrl":"10.1002/dug2.12023","url":null,"abstract":"<p>Rapid coal-rock identification is one of the key technologies for intelligent and unmanned coal mining. Currently, the existing image recognition algorithms cannot satisfy practical needs in terms of recognition speed and accuracy. In view of the evident differences between coal and rock in visual attributes such as color, gloss and texture, the complete local binary pattern (CLBP) image feature descriptor is introduced for coal and rock image recognition. Given that the original algorithm oversimplifies local texture features by ignoring imaging information from higher-order pixels and the concave and convex areas between adjacent sampling points, this paper proposes a higher-order differential median CLBP image feature descriptor to replace the original CLBP center pixel gray with a local gray median, and replace the binary differential with a second-order differential. Meanwhile, for the high dimensionality of CLBP descriptor histogram and feature redundancy, deep learning perceptual field theory is introduced to realize data nonlinear dimensionality reduction and deep feature extraction. With relevant experiments conducted, the following conclusion can be drawn: (1) Compared with that of the original CLBP, the recognition accuracy of the improved CLBP algorithm is greatly improved and finally stabilized above 94.3% under strong noise interference; (2) Compared with that of the original CLBP model, the single image recognition time of the coal rock image recognition model fusing the improved CLBP and the receptive field theory is 0.0035 s, a reduction of 71.0%; compared with the improved CLBP model (without the fusion of receptive field theory), it can shorten the recognition time by 97.0%, but the accuracy rate still maintains more than 98.5%. The method offers a valuable technical reference for the fields of mineral development and deep mining.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 2","pages":"165-173"},"PeriodicalIF":0.0,"publicationDate":"2022-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12023","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90241676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogeological feasibility of mine water deep geological storage in Baotashan coarse sandstone: A case study in Ordos Basin","authors":"Ge Chen,&nbsp;Yajun Sun,&nbsp;Zhimin Xu,&nbsp;Xin Li","doi":"10.1002/dug2.12022","DOIUrl":"10.1002/dug2.12022","url":null,"abstract":"<p>For the sake of mine water drainage and sustainable groundwater protection, the new approach of mine water deep geological storage (MWDGS) is highly necessary to save water resources in the semi-arid region of China. However, up to now, little academic research has been done on mine water geological storage. Given this situation, the hydrogeological feasibility of MWDGS was explored in Baotashan coarse sandstone (BCS) of Jurassic measure in Ordos Basin. The results show that the white-gray BCS with a fragile skeleton of quartz (41.4%), feldspar (21.1%), and clay minerals (16.4%) provides the potential variable-void for mine water; and its hydro-chemical type of BCS aquifer is CO₃-Na and Cl-Na. As the burial depth increases, the strong alkaline groundwater is in stagnant and poor recharge-runoff-discharge condition. The lab test shows that the pores whose diameter is over 10 μm could be treated as the main storage of mine water; and the effective porosity varies from 1.36% to 3.46%. When mine water is injected, the strong hydrodynamics of mine water storage would change the permeability significantly and about 0.201% soluble solids would be dissolved. Partial clay minerals obstruct the pores and induce the saturated phase of high permeability to evolve into steady phase of lower permeability. Under the condition of nonhydraulic fracturing during continuous storage, the heterogeneous anisotropic medium obtained by Transition PRObability GeoStatistics (TPROGS) shows that the capacity of BCS aquifer is 0.455 to 1.226 Mm³ for 1 km² in the study area. The simulation shows that the groundwater mound in well-scale and mine-scale would be formed. The groundwater quality characteristics of “Three Zone” would occur around and gradually drop to approximate the original brine within 10 years. The hydrogeological feasibility reveals that this approach is useful for the well design and groundwater environment management during the mine water deep geological storage project in the Ordos basin.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 2","pages":"148-164"},"PeriodicalIF":0.0,"publicationDate":"2022-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12022","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84508095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of rockburst proneness considering specimen shape by storable elastic strain energy","authors":"Song Luo,&nbsp;Fengqiang Gong","doi":"10.1002/dug2.12020","DOIUrl":"10.1002/dug2.12020","url":null,"abstract":"<p>To systematically assess the rockburst proneness considering specimen shape, multiple groups of laboratory tests were performed on 5 rock materials in cylindrical and cuboid shapes. The linear energy storage (LES) law of both cylindrical and cuboid rock specimens under uniaxial compressive load was confirmed, and the energy storage coefficient was found to be unrelated to specimen shape. On the basis of LES law, two rockburst proneness indexes, namely the strain energy storage index (<i>W</i>_et) and the potential energy of elastic strain (PES), were modified. Subsequently, the <i>W</i>_et, PES, peak-strength strain energy storage index (, and peak-strength potential energy of elastic strain (PES^p) were used to assess the rockburst proneness of the cylindrical and cuboid specimens. In addition, the fragment ejection course of specimens under test was recorded by a high-speed camera. Then, the rockburst proneness judgments obtained from the 4 indexes were compared with the qualitative data during rock destruction. The results show that, under similar stress conditions, specimen shape has an ignorable effect on the rockburst proneness as a whole. The judgment accuracy of the two modified indexes, especially that of the PES^p, is favorably improved to evaluate the rockburst proneness of both cylindrical and cuboid specimens. However, misjudgment of and PES^p may still occur in the assessment of rockburst proneness as these two indexes only consider the energy state before rock peak strength and the is formulated in a ratio form.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 2","pages":"116-130"},"PeriodicalIF":0.0,"publicationDate":"2022-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90341128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fracture distribution in overburden strata induced by underground mining","authors":"Wenli Yao,&nbsp;Enzhi Wang,&nbsp;Xiaoli Liu,&nbsp;Ran Zhou","doi":"10.1002/dug2.12021","DOIUrl":"10.1002/dug2.12021","url":null,"abstract":"<p>Coal-mining activities give rise to a series of ecological environmental problems, such as ground settlement and groundwater pollution. In fact, they are mainly caused by mining-induced fractures. Hence, it is necessary to study the mining-induced fracture distribution to identify the behavior of rock mass movement. However, the fractures in overburden strata cannot be directly measured owing to the special condition. Therefore, the majority of previous studies are based on experiments or experience. For this reason, this study first used a discrete element method to simulate the shape of mining-induced fractures in overburden strata. Then, a geophysical tool of transient electromagnetic method (TEM) was used to investigate the mining-induced fracture distribution. Based on the low-resistivity anomaly area, the water-rich area in overburden strata was analyzed to be mainly caused by fracture seepage. Through the mutual authentication between numerical simulation and TEM results, the mining-induced fractures in overburden strata were explored. This study can enhance the understanding of mining-induced fracture distribution on the one hand and guarantee the coal mining safety on the other, thus guiding the coordinated development between coal mining and environmental protection.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 1","pages":"58-64"},"PeriodicalIF":0.0,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90678404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stress wave propagation and incompatible deformation mechanisms in rock discontinuity interfaces in deep-buried tunnels","authors":"Cong Zhang,&nbsp;Zhende Zhu,&nbsp;Shanyong Wang,&nbsp;Xuhua Ren,&nbsp;Chong Shi","doi":"10.1002/dug2.12016","DOIUrl":"10.1002/dug2.12016","url":null,"abstract":"<p>Complex weak structural planes and fault zones induce significant heterogeneity, discontinuity, and nonlinear characteristics of a rock mass. When an earthquake occurs, these characteristics lead to extremely complex seismic wave propagation and vibrational behaviors and thus pose a huge threat to the safety and stability of deep buried tunnels. To investigate the wave propagation in a rock mass with different structural planes and fault zones, this study first introduced the theory of elastic wave propagation and elastodynamic principles and used the Zoeppritz equation to describe wave field decomposition and develop a seismic wave response model accordingly. Then, a physical wave propagation model was constructed to investigate seismic waves passing through a fault, and dynamic damage was analyzed by using shaking table tests. Finally, stress wave attenuation and dynamic incompatible deformation mechanisms in a rock mass with fault zones were explored. The results indicate that under the action of weak structural planes, stress waves appear as a complex wave field decomposition phenomenon. When a stress wave spreads to a weak structural plane, its scattering may transform into a tensile wave, generating tensile stress and destabilizing the rock mass; wave dynamic energy is absorbed by a low-strength rock through wave scattering, which significantly weakens the seismic load. Wave propagation accelerates the initiation and expansion of internal defects in the rock mass and leads to a dynamic incompatible deformation. This is one of the main causes for large deformation and even instability within rock masses. These findings provide an important reference and guide with respect to stability analysis of rock mass with weak structural planes and fault zones.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"1 1","pages":"25-39"},"PeriodicalIF":0.0,"publicationDate":"2022-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.12016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87438841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}