Geomechanics and Engineering最新文献

{"title":"An analytical approach to estimate the mechanical state of roof strata in underground longwall mining","authors":"J. Zhang, Yansong Zhang, Wenzhou Du, Houwang Wang, M. Serati","doi":"10.12989/GAE.2021.27.1.057","DOIUrl":"https://doi.org/10.12989/GAE.2021.27.1.057","url":null,"abstract":"The movement and collapse of roof strata in underground longwall mining is a key trigger factor for the occurrence of dynamic disasters. An accuracy estimation of roof strata mechanical state is critical for the prediction and control of dynamic disaster, such as coal burst and coal-and-gas outburst. An analytical approach is proposed in this work to estimate the mechanical state of roof strata in underground longwall mining. To do so, the unit width of roof strata is considered as a beam structure. A system of 4 simulations differential equations is proposed with 4 local slope data as input parameters to derive the mechanical expression of suspending roof strata. A differential evolution algorithm is further adapted to solve the equation system. In addition, a set of verification tests is carried out to showcase the feasibility and robustness of the proposed method. The results show that the average relative errors of 10 independent tests reach a high accuracy, which is less than 1% for the strata mechanical state control parameters. By using the estimated results, the slope, bending moment and shear force of suspending strata are derived. Moreover, the slope data sampling strategy is also devised. The parameters bound determination method is also proposed to ensure the calculation convergence. The local slope based analytical method proposed in this paper is a feasible approach to estimate the mechanical state of suspended roof strata before first weighting.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41548003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating of free vibration behavior of bidirectional FG beams resting on variable elastic foundation","authors":"Ismail Benaberrahmane, S. Benyoucef, M. Sekkal, M. Mekerbi, R. B. Bouiadjra, M. Selim, A. Tounsi, M. Hussain","doi":"10.12989/GAE.2021.25.5.383","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.5.383","url":null,"abstract":"In the present study, the free vibration of bidirectional functionally graded (FG) beams resting on variable elastic foundation are comprehensively investigated. The beam’s behavior is modeled using 2D displacement field that contain undetermined integral terms and involves a reduced unknown functions. The material properties of the FG beam are assumed to be graded in both the thickness and longitudinal directions according to a power law. The beams are considered simply supported and resting on variable elastic foundation. The differential equation system governing the free vibration behavior of bidirectional beams is derived based on the Hamilton principle. The problem is then solved using the Navier solution for a simply supported beam. The accuracy of the used model can be noticed by comparing it with other solutions available in the literature where a good conformance was obtained. A detailed parametric study is conducted to explore the influences of material composition and variable elastic parameters on the vibration characteristics of the beams. The results reveal that the grading indexes in one or both directions as well as the parameters of the elastic foundation strongly impact the fundamental frequencies.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49133316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of grout penetration in single rock fracture using electrical resistivity","authors":"Hangbok Lee, T. Oh, Jong-Won Lee","doi":"10.12989/GAE.2021.24.1.001","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.1.001","url":null,"abstract":"In this study, a new approach using electrical resistivity measurement was proposed to detect grout penetration and to evaluate the grouting performance for such as waterproof efficiency in single rock fracture. For this purpose, an electrical resistivity monitoring system was designed to collect multi-channel data in real time. This was applied to a system for grout injection/penetration using a transparent fracture replica with various aperture sizes and water-cement mix ratio. The electrical resistivity was measured under various grout penetration conditions in real time, which results were directly compared to the visual observation images of grout penetration/distribution. Moreover, the grouting success status after the curing process was evaluated by measuring the electrical resistivity in relation to changes in frequency in fracture cells where grout injection and penetration were completed. Consequently, it was determined that the electrical resistivity monitoring system could be applied effectively to the detection of successful penetration of grouting into a target area and to actual field evaluation of the grouting performance and long-term stability of underground rock structures.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66471533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel preloading method for foundation underpinning for the remodeling of an existing building","authors":"Chengcan Wang, Jin-Tae Han, S. Kim, Y. Jang","doi":"10.12989/GAE.2021.24.1.029","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.1.029","url":null,"abstract":"The utilization of buildings can be improved by extending them vertically. However, the added load of the extension might require building foundations to be underpinned; otherwise, the loads on the foundations might exceed their bearing capacity. In this study, a preloading method was presented aiming at transferring partial loads from existing piles to underpinning piles. A pneumatic-type model preloading device was developed and used to carry out centrifuge experiments to evaluate the load–displacement behavior of piles, the pile–soil interaction during preloading, and the additional loading caused by vertical extension. The results showed that the preloading devices effectively transfer load from existing piles to underpinning piles. In the additional loading test of group piles, the load-sharing ratio of a pile increased with its stiffness. The load-sharing ratio of a preloaded micropile was less than that of a non-preloaded micropile as a result of the reduction in axial stiffness caused by preloading before additional loading. Therefore, a slight reduction of the load-sharing capacity of an underpinning pile should be considered if the preloading method is applied. Further, two full scale preloading devices was developed. The devices preload underpinning piles and thereby produce reaction forces on a reaction frame to jack existing piles upward, thus transferring load from the existing piles to the underpinning piles. Specifically, screw-type and hydraulic-jack type devices were developed for the practical application of foundation underpinning during vertical extension, and their operability and load transfer effect verified via full-scale structural experiments.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66471634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seismic response of utility tunnels subjected to different earthquake excitations","authors":"Chenglong Wang, Xuan-ming Ding, Zhi-xiong Chen, Li Feng, Liang Han","doi":"10.12989/GAE.2021.24.1.067","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.1.067","url":null,"abstract":"The influence of ground motions on the seismic response of utility tunnels was investigated. A series of small-scale shaking table model tests were carried out under uniform excitation in the transverse direction. Different peak accelerations of EL-Centro and Taft earthquake waves were applied. The acceleration responses, earth pressure, seismic strain, bending moment and structure deformations were measured and discussed. The results showed that the types of earthquake waves had significant influences on the soil-structure acceleration responses. However, the amplitude of the soil acceleration along the depth showed consistent variation regardless of the types of earthquake waves and tunnels. The horizontal soil pressure near the top and bottom slabs showed obviously larger values than those at other depths. In general, the strain response in the outer surface was more significant than that on the inner surface, and the peak strain in the end section of the model was larger than that in the middle section. Moreover, the bending moment at the corner points was much larger than that at middle point, and the bending moment was greatly affected by both input accelerations and seismic wave types. The opposite direction of shear deformation on the top and bottom slabs presented a rotation trend of the model structure.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66471967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the crack propagation rules and regional damage characteristics of rock specimens","authors":"Liu Yangyang, Xue Yadong, Shichuan Zhang, F. Jing, Du Guobin, Sukai Lu, Guangsheng Fu","doi":"10.12989/GAE.2021.24.3.215","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.3.215","url":null,"abstract":"To study the evolution mechanism of cracks in rocks with multiple defects, rock-like samples with multiple defects, such as strip-shaped through-going cracks and cavity groups, are used, and the crack propagation law and changes in AE (acoustic emission) and strain of cavity groups under different inclination angles are studied. According to the test results, an increase in the cavity group inclination angle can facilitate the initial damage degree of the rock and weaken the crack initiation stress; the initial crack initiation direction is approximately 90°, and the extension angle is approximately 75~90° from the strip-shaped through-going cracks; thus, the relationship between crack development and cavity group initiation strengthens. The specific performance is as follows: when the initiation angle is 30°, the cracks between the cavities in the cavity group develop relatively independently along the parallel direction of the external load; when the angle is 75°, the cracks between the cavities in the cavity group can interpenetrate, and slip can occur along the inclination of the cavity group under the action of the shear mechanism rupture. With the increase in the inclination angle of the cavity group, the AE energy fluctuation frequency at the peak stress increases, and the stress drop is obvious. The larger the cavity group inclination angle is, the more obvious the energy accumulation and the more severe the rock damage; when the cavity group angle is 30° or 75°, the peak strain of the local area below the strip-shaped through-going fracture plane is approximately three times that when the cavity group angle is 45° and 60°, indicating that cracks are easily generated in the local area monitored by the strain gauge at this angle, and the further development of the cracks weakens the strength of the rock, thereby increasing the probability of major engineering quality damage. The research results will have important reference value for hazard prevention in underground engineering projects through rock with natural and artificial defects, including tunnels and air-raid shelters.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vibration of multilayered functionally graded deep beams under thermal load","authors":"A. Bashiri, Ş. Akbaş, A. Abdelrahman, A. Assie, M. A. Eltaher, E. Mohamed","doi":"10.12989/GAE.2021.24.6.545","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.6.545","url":null,"abstract":"Since the functionally graded materials (FGMs) are used extensively as thermal barriers in many of applications. Therefore, the current article focuses on studying and presenting dynamic responses of multilayer functionally graded (FG) deep beams placed in a thermal environment that is not addressed elsewhere. The material properties of each layer are proposed to be temperature-dependent and vary continuously through the height direction based on the Power-Law function. The deep layered beam is exposed to harmonic sinusoidal load and temperature rising. In the modelling of the multilayered FG deep beam, the two-dimensional (2D) plane stress continuum model is used. Equations of motion of deep composite beam with the associated boundary conditions are presented. In the frame of finite element method (FEM), the 2D twelve –node plane element is exploited to discretize the space domain through the length-thickness plane of the beam. In the solution of the dynamic problem, Newmark average acceleration method is used to solve the time domain incrementally. The developed procedure is verified and compared, and an excellent agreement is observed. In numerical examples, effects of graduation parameter, geometrical dimension and stacking sequence of layers on the time response of deep multilayer FG beams are investigated with temperature effects.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66475045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental research on the effect of water-rock interaction in filling media of fault structure","authors":"Dong Faxu, Peng Zhang, Sun Wenbin, Shaoliang Zhou, Kong Lingjun","doi":"10.12989/GAE.2021.24.5.471","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.5.471","url":null,"abstract":"Water damage is one of the five disasters that affect the safety of coal mine production. The erosion of rocks by water is a very important link in the process of water inrush induced by fault activation. Through the observation and experiment of fault filling samples, according to the existing rock classification standards, fault sediments are divided into breccia, dynamic metamorphic schist and mudstone. Similar materials are developed with the characteristics of particle size distribution, cementation strength and water rationality, and then relevant tests and analyses are carried out. The experimental results show that the water-rock interaction mainly reduces the compressive strength, mechanical strength, cohesion and friction Angle of similar materials, and cracks or deformations are easy to occur under uniaxial load, which may be an important process of water inrush induced by fault activation. Mechanical experiment of similar material specimen can not only save time and cost of large scale experiment, but also master the direction and method of the experiment. The research provides a new idea for the failure process of rock structure in fault activation water inrush.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66475168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the effect of void ratio and particle breakage on saturated hydraulic conductivity of tailing materials","authors":"Changkun Ma, Chao Zhang, Qinglin Chen, Zhenkai Pan, Lei Ma","doi":"10.12989/GAE.2021.25.2.159","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.2.159","url":null,"abstract":"Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66476273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional finite element analysis of urban rock tunnel under static loading condition: Effect of the rock weathering","authors":"Mohammad Zaid","doi":"10.12989/GAE.2021.25.2.099","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.2.099","url":null,"abstract":"Tunnel provide faster, safer and convenient way of transportation for different objects. The region where it is construction and surrounding medium has significant influence on the overall stability and performance of tunnel. The present simulation has been carried out in order to understand the behaviour of rock tunnel under static loading condition. The present numerical model has been validated with the laboratory scaled model and field data of underground tunnels. Both lined and unlined tunnels have been considered in this paper. Finite element technique has been considered for the simulation of static loading effect on tunnel through Abaqus/Standard. The Mohr-Coulomb material model has been considered to simulate elastoplastic nonlinear behaviour of different rock types, i.e., Basalt, Granite and Quartzite. The four different stages of rock weathering are classified as fresh, slightly, moderately, and highly weathered in case of each rock type. Moreover, extremely weathered stage has been considered in case of Quartzite rock. It has been concluded that weathering of rock and overburden depth has great influence on the tunnel stability. However, by considering a particular weathering stage of rock for each rock type shows varying patterns of deformations in tunnel.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66476423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}