Numerical simulation for influence of excavation and blasting vibration on stability of mined-out area

Dynamic analysis steps and general flow of fast lagrangian analysis of continua in 3 dimensions(FLAC3D) were discussed. Numerical simulation for influence of excavation and blasting vibration on stability of mined-out area was carried out with FLAC3D. The whole analytical process was divided into two steps, including the static analysis and the dynamic analysis which were used to simulate the influence of excavation process and blasting vibration respectively. The results show that the shape of right upper boundary is extremely irregular after excavation, and stress concentration occurs at many places and higher tensile stress appears. The maximum tensile stress is higher than the tensile strength of rock mass, and surrounding rock of right roof will be damaged with tension fracture. The maximum displacement of surrounding rock is 4.75 mm after excavation. However, the maximum displacement increases to 5.47 mm after the blasting dynamic load is applied. And the covering area of plastic zones expands obviously, especially at the foot of right upper slope. The analytical results are in basic accordance with the observed results on the whole. Damage and disturbance on surrounding rock to some degree are caused by excavation, while blasting dynamic load increases the possibility of occurrence of dynamic instability and destruction further. So the effective supporting and vibration reducing measures should be taken during mining.

Numerical simulation of surface movement laws under different unconsolidated layers thickness

Based on specific geology and mining conditions of certain coal working face in China, a series of numerical models under different unconsolidated layers thickness were respectively established by employing FLAC3D. The relationship between the unconsolidated layers thickness and surface movement laws was studied. Maximum surface subsidence, Maximum horizontal displacement and surface subsidence degree were obtained. Contours of surface subsidence/horizontal displacement and curves were drawn. Some laws of surface subsidence/horizontal displacement were analyzed. The role of the unconsolidated layers in surface subsidence was revealed. It is significant to predict surface subsidence of thick unconsolidated layers for coal mine and take effective measures to control surface subsidence.

Novel modeling on numerical computing the geo-deformation information in coalmine based on the GIS-Excel

Numerical simulation modeling is a hotspot in the geological engineering computing field. Tak- ing a fast Langrangian analysis of continua in 3 dimensions （FLAC3D） numerical modeling on com- puting the geo-deformation information caused by the mining subsidence in a coalmine for example, a new GIS-Excel modeling method is proposed to build geologic strata within the simulation range combined with the coal-seam dip angle of the underground mining working-planes. First of all, the coal-seam model of the numerical computing is built by using the geographic information system （GIS） according to the stripe-through principle and the calculating formula on the size of the model blocks in the paper defined, then the FLAC3D numerical computing model of all geologic strata with- in the simulation range is also built based on the calculating formula of thickness of each stratum and the Excel fast computing advantages. The GIS-Excel method is good at the higher modeling accuracy, seldom making mistakes and consuming less time. The reliability and validity of the method is veri- fied well by its practical applications in the coalmine area.

Numerical Study on Effect of Longwall Mining on Stability of Main Roadway under Weak Ground Conditions in Indonesia

The purpose of this research is to study the effect of longwall mining on the stability of main roadway in the underground coal mine. The PT GDM （Gerbang Daya Mandiri） underground coal mine in Indonesia, where the rocks are weak, was selected as a representative study site. To accomplish the objective of the research, the finite difference code software FLAC3D was used as a tool for the numerical simulations. The longwall mining of several panel and barrier pillar widths at various depths was simulated and discussed. Based on the simulation results, it indicates that the effect of coal panel extraction on the main roadway stability depends on the width of panel and barrier pillar. The greatest effect occurs when the large panel width and the small barrier pillar width are applied, whereas the smallest effect happens when the narrow panel width and the large barrier pillar width are adopted. In this paper, therefore, to maintain the stability of the main roadway with the aim of maximizing the coal recovery, the appropriate size of panel and barrier pillar width is proposed for each mining depth for this underground coal mine.

Development and Properties of Glass Fiber Reinforced Plastics Geogrid

Glass fiber reinforced plastics geogrid has a wide application in the field of soil reinforcement because of its high strength, good toughness, and resistance to environmental stress, creep resistance and strong stability. In order to get high-powered glass fiber reinforced plastics geogrid and its mechanical characteristics, the properties and physical mechanical index of geogrid have been got through the study of its raw material, production process and important quality index. The analysis and study have been made to the geogrid＇s mechanical properties with loading speed, three-axial compression, temperature tensile test and FLAC3D numerical simulation, thus obtain the mechanical parameters of its displacement time curve, breaking strength and elongation at break. Some conclusions can be drawn as follows： （a） Using glass fiber materials, knurling and coated projection process, the f^acture strength and corrosion resistance of geogrid are greatly improved and the interlocking bite capability of soil is enhanced. （b） The fracture strength of geogrid is related to temperature and loading rate. When the surrounding rock pressure is fixed, the strength and anti-deformation ability of reinforced soil are significantly enhanced with increasing reinforced layers. （c） The pullout test shows the positive correlation between geogrid displacement and action time. （d） As a new reinforced material, the glass fiber reinforced plastics geogrid is not mature enough in theoretical research and practical experience, so it has become an urgent problem both in theoretical study and practical innovation.

Using true‑triaxial stress path to simulate excavation‑induced rock damage:a case study

This study presents an example illustrating the role of in situ 3D stress path method in simulating the roof damage development observed in the Mine-by tunnel at Underground Research Laboratory(URL)located in Manitoba,Canada.The 3D stress path,at the point 1 cm in the crown of the Mine-by tunnel,was applied to a cubic Lac du Bonnet(LdB)granite sample to further understand the roof damage process and the associated seismicity.After careful calibrations,a numerical model was used to reproduce the experiment,which produced similar seismicity processes and source mechanisms.Acoustic emission(AE)events obtained from laboratory and numerical modeling were converted to locations in relation to the tunnel face and were compared to the feld microseismicity(MS)occurring in the upper notch region of the Mine-by tunnel.The crack development and damage mechanism are carefully illustrated.The diference between tests and feld monitoring was discussed.The intermediate principal stress(σ_(2))unloading process was carried out in numerical simulation to investigate its role in rock damage development.The results clearly showedσ_(2)could play a signifcant role both in damage development and failure mode.It should be considered when predicting the damage region in underground excavations.This study highlights the potential role of laboratory and numerical stress path tests to investigate fracture processes and mechanisms occurring during engineering activities such as tunnel excavation.

Support technology for mine roadways in extreme weakly cemented strata and its application

For the engineering geology conditions of bad mine roadway roof and floor lithology in extremely weak cemented strata, the best section shape of the roadway is determined from the study of tunnel surrounding rock displacement, plastic zone and stress distribution in rectangular, circle arch and arch wall sections, respectively. Based on the mining depth and thickness of the coal seam, roadway support technology solutions with different buried depth and thickness of coal seam are proposed. Support schemes are amended and optimized in time through monitoring data of the deformation of roadway, roof separation, l-beam bracket, bolt and anchor cable force to ensure the long-term stability and security of the roadway surrounding rock and support structure. The monitoring results show that mine roadway support schemes for different buried depth and section can be adapted to the characteristics of ground pressure and deformation of the surrounding rock in different depth well, effectively control the roadway surrounding rock deformation and the floor heave and guarantee the safety of construction and basic stability of surrounding rock and support structure.

Experimental study on the movement law of overlying rock non-pillar coal overhead mining

Pillarless coal mining technology is a new practical technology.Based on the compensating mechanical behavior of the Negative Poisson’s Ratio(NPR)anchor cable on the roof,the roadway was successfully retained by the top cutting and pressure relief technology.This study utilizes the Digital Speckle Monitoring(DIC monitoring),stress-strain monitoring,and infrared thermal imaging systems to conduct physical model experiment of similar materials from the displacement,stress-strain,and temperature fields to investigate in depth the fracture change law of the overlying rock.In addition,it uses FLAC3D numerical simulation to invert the surface displacement settlement.The results show that the non-pillar overhead mining under the 110 mining method has little influence on the rock crack in the middle of the coal seam,and the crack development area is mainly concentrated in the overlying rock mass of the upward coal seam.The compensatory mechanical behavior of NPR anchor cable and the dilatation characteristics of rock mass have a good effect of retaining roadway along goaf,and can also reduce surface settlement.The 110 mining method provides a scientific basis for ecological environment protection and the development of other kilometer deep soft rock high ground stress underground projects.

Dynamic response analysis of liquefiable ground due to sinusoidal waves of different frequencies of shield construction

Vibration induced by shield construction can lead to liquefaction of saturated sand.Based on FLAC3D software,a numerical model of tunnel excavation is established and sinusoidal velocity loads with different frequencies are applied to the excavation face.The pattern of the excess pore pressure ratio with frequency,as well as the dynamic response of soil mass under different frequency loads before excavation,is analyzed.When the velocity sinusoidal wave acts on the excavation surface of the shield tunnel with a single sand layer,soil liquefaction occurs.However,the ranges and locations of soil liquefaction are different at different frequencies,which proves that the vibration frequency influences the liquefaction location of the stratum.For sand-clay composite strata with liquefiable layers,the influence of frequency on the liquefaction range is different from that of a single stratum.In the frequency range of 5-30 Hz,the liquefaction area and surface subsidence decrease with an increase in vibration frequency.The research results in this study can be used as a reference in engineering practice for tunneling liquefiable strata with a shield tunneling machine.

Study on the Safety of the Foundation Rock Masses in the Tangkou Bank of the Taipinghu Bridge

The Taipinghu Bridge is an important project, and the safety of rock masses of its foundation is very crucial. This article analyzes the potential causes of the deformation of the rock masses of the bridge foundation, and uses the Fast Lagrangian Analysis of Continua to analyze the geologic model. The simulating process shows that no mater in the excavating process or in the loading process the rock masses are suit for the engineering. The modeling and analyzing process can be used for reference.

赵庄二号井3~#煤层陷落柱防水煤柱数值模拟研究

运用FLAC-3D软件对赵庄二号井的DX17陷落柱的防水煤柱进行了数值模拟研究。通过留设不同宽度的保护煤柱，分析煤系煤层周围及陷落柱附近塑性区及最小主应力变化情况，得出了陷落柱防水煤柱的合理留设宽度，3#煤层临近陷落柱开采时，留设70m的防水煤柱是可靠的。

Study on the Safety of the Rock Mass in the Tongling Bank of Taipinghu Bridge

The Taipinghu Bridge is an important engineering construction, and the safety of rock mass of its foundation is very crucial. This article adopts FLAC 3D to analysis the geologic model. The simulating process shows that no mater the excavating process or the loading process the rock mass are safe. The modeling and analyzing process can be used for reference.

煤层开采对地表变形影响的数值模拟研究

为研究分析煤层开采对地表变形的影响,本文通过FLAC3D数值模拟软件采用摩尔-库伦,弹性及德鲁克-普拉格3种本构模型分别模拟研究,对地表建筑物竖直和水平位移进行模拟研究,并与概率积分计算方法所得的理论计算结果进行对比分析得出:数值模拟计算与理论计算,均可得出竖直和水平位移均为靠近开采处逐渐增大,远离开采处逐渐减小并趋于稳定.在3种本构模型中,摩尔-库伦本构模型更适合用于煤层开采对地表变形影响的数值模拟.

Law of surface movement for multi-coal seam strip mining

It is an important part of green mining to control the disasters of coal mining which have caused irreversible damages to buildings and ecological environment. Strip mining is one of the efficient measures to control surface subsidence and mining damage. However, the research on the laws of the surface subsidence are still deficient in multi-coal seam strip mining at present. Based on the Fast Lagrangian Analysis of Continua(short for FLAC3D) numerical simulation software, the laws of the surface subsidence and horizontal movement were systematically studied for different depths, different mining widths, different distances between seams, different mining thickness, different parameters between seams and the special relations of the upper pillar and the lower pillar in the vertical direction in multi-seam strip mining. The function relation between the maximum subsidence and the maximum horizontal movement with the depth, the mining width, the seam distance, mining thickness, different parameters between seams and the partial offset are summarized respectively. Finally the formula integrating the surface maximum subsidence value and the maximum horizontal movement was deduced. The results can be used for reference theory and measure in forecasting the surface displacement in multi-coal seam strip mining.

超深基坑支护开挖对土体变形影响数值模拟研究

研究目的:为了掌握基坑开挖引起的围护结构变形和地层沉降的计算模拟方法,利用理论分析、数值模拟,以土与支护结构相互作用稳定性为研究核心,对深基坑开挖过程中引起的土层位移、地表沉降分布规律以及支护结构的位移、应力改变等相关内容进行研究,掌握基坑开挖引起的围护结构变形和地层沉降的计算模拟方法,从而指导设计工作。研究结果:基坑开挖至设计深度并完成底板施工时,模拟计算基坑外缘地表最大沉降为28.7 mm,施工过程中实测结果为28.46 mm,模拟分析计算结果与实际工程监测结果大致吻合,故研究结果可以指导设计工作。

Analysis of stability of coal pillars with multi-coal seam strip mining

Strip mining is one of the efficient measures to control surface subsidence and mining damage. However, the researches on the laws of the geological mining factors to upper and lower pillar's stability are still deficient in multi-coal seam strip mining at present. Based on the three dimension fast Lagrangian analysis of continua (short for FLAC3D) numerical simulation software, the laws of the stress increasing coefficient on the coal pillar and its stability were systematically studied for different depths, different mining widths, different interlayer spacings, different mining thicknesses, different properties of interstratified rock and the spacial relations of the upper and lower pillars in vertical alignment in multi-coal seam strip mining. The function relation between the stress increasing coefficient of upper and lower pillars with the mining depth, mining widths, interlayer spacing, mining thickness, property of interstratified rock and the spatial relationship were obtained.

热-应力耦合作用下深部软岩隧洞大变形三维数值模拟分析

高地温是深部隧洞的一个重要特点,温度场的存在必然会影响到深部隧洞的变形和应力状况,特别是考虑到深部隧洞的高地应力和大变形的特性,温度场的影响就更加显著。因此,本文基于摩尔-库仑本构模型,利用FLAC3D软件对深部软岩隧洞洞室围岩的力学响应及其在不同温度场作用影响下的应力、变形及塑性区分布等指标的分布及变化情况进行模拟计算及研究分析,得出了一定基本规律,为工程设计提供参考。

辽河油田锦16块第一层系油藏开发调整数值模拟

本文应用根据水动力学原理建立油藏内三维三相流动模型所编制的计算机软件,对辽河油田具有多年开发历史的锦16块第一层系进行数值模拟研究.采用三种不同方案预测到2003年时的开发指标,对油田开发调整具有很强的指导作用.

充填体下矿体回采顺序数值模拟优化研究

结合矿山的采矿方法及矿体赋存特征,采用FLAC3D数值模拟软件,建立了三维数值模型,对矿体在大体积充填体下的回采顺序进行了模拟研究,根据计算结果,从应力、位移及塑性区3个方面对不同的方案进行了比较分析,进而确定从中间向两翼的回采顺序为最优回采顺序,并针对矿山在未来开采中可能存在的问题提出了合理建议,分析结果对矿山的安全生产有重要的参考价值。