Deformation and failure of a high-steep slope induced by multi-layer coal mining

During underground mining,accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines.Numerical simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining conditions.By utilising PFC2 D(particle flow code) software,the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province,China were investigated.Additionally,the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was elucidated.The result showed that after the goaf passed by the slope toe,multi-layer mining aggravated the subsidence and deformation of the slope toe:the slope toppled forward as it sank.The toppling of the slope changed the slope structures:the strata in the front of the slope were transformed from anti-dip to down-dip features.Extruded by collapsedtoppled rock mass,the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the slope.Multi-layer mining degraded the overall stability of the slope,in that the total displacement of the slope was much greater than the total mining thickness of the coal seams.Based on the aforementioned research,ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.

Study on high and steep slope stability of surface mine based on RFPA-SRM

The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pingzhuang Western Surface Mine and based on strength reduction method, the dynamic instability processes of the top high and steep slope was simulated. Also, the landslide mode was determined, the characteristics of the displacement distribution, the deformation, failure, and the stress distribution in the slope were demonstrated, and the stability was calculated. Conclusions can be drawn as follows： the landslide or failure of high and steep slopes on a surface mine is a gradual process, in which the slope undergoes the generation, expansion, and connection of the fractures and the displacement increases until landslide occurs; a small portion of the upper rocks fail due to the tension and the lower rocks fail due to the shear; the potential sliding surface is combined and the essential cause of the landslide is the shear stress concentration.

Research on Deformation and Force of Bridge Pile Foundation on High and Steep Slope in Mountainous Area

With the rapid development of my country’s economy, the demand for infrastructure construction is also increasing. However, in most areas of China, the terrains are mountainous and hilly. Some projects have to be built on steep slopes. Choosing viaducts or half-bridges on high-steep slopes is not only conducive to the protection of the surrounding environment, but also conducive to the stability of the slope. Bridges usually choose the form of pile foundation-high pier bridge. This paper uses numerical simulation to study and analyze the bridge pile foundation of the slope section. Relying on actual engineering, use the finite element software ABAQUS6.14 to establish a three-dimensional finite element model to study the bearing mechanism and mechanical characteristics of the pile foundation under vertical load, horizontal load and inclined load, discuss the influence of the nature of the soil around the pile and the stiffness of the pile body on the deformation and internal force of the bridge pile foundation in the slope section. The analysis results show that the horizontal load has a great influence on the horizontal displacement of the pile, but has a small influence on the vertical displacement, and the vertical load is just the opposite. Inclined load has obvious “p-Δ” effect. The increase in soil elastic modulus and pile stiffness will reduce the displacement of the pile foundation, but after reaching a certain range, the displacement of the pile foundation will tend to be stable. Therefore, in actual engineering, if the displacement of the pile foundation fails to meet the requirements, the hardness of the soil and the stiffness of the pile can be appropriately increased, but not blindly.

Application of Three-Dimensional Laser Scanning and Surveying in Geological Investigation of High Rock Slope

The appearance of 3D laser scanning technology is one of the most important technology revolutions in surveying and mapping field. It can be widely used in many interrelated fields, such as engineering constructions and 3D measurements, owing to its prominent characteristics of the high efficiency and high precision. At present its application is still in the initial state, and it is quite rarely used in China, especially in geotechnical engineering and geological engineering fields. Starting with a general introduction of 3D laser scanning technology, this article studies how to apply the technology to high rock slope investigations. By way of a case study, principles and methods of quick slope documentation and occurrence measurement of discontinuities are discussed and analyzed. Analysis results show that the application of 3D laser scanning technology to geotechnical and geological engineering has a great prospect and value.

GIS-based 3D limit equilibrium analysis for design optimization of a 600 m high slope in an open pit mine

Combining the GIS （geographic information systems） grid-based data with four proposed column-based 3D slope stability analysis models, a comprehensive solution of a high-steep open-pit slope has been obtained. For six searching ranges, 19 critical slip surfaces of different sizes have been studied, in which the minimum 3D safety factor is 1.33. Comparison of 3D safety factors of designed and proposed slope plans shows for all the critical slip surfaces for the proposed plan, the smallest 3D safety factor is 1.33 under the most unfavorable condition. This means that the proposed plan of the high slopes, about 600 m, of an open pit （2-5° steeper than designed plan） is feasible.

Research on Effect of Heap Loading on Deformation and Mechanical Properties of Bridge Double Pile Foundation on Steep Slope

In order to analyze the deformation and stress characteristics of the pile foundation on the slope, this paper uses the finite element software Abaqus for numerical simulation. The displacement and stress data of pile under different working conditions (the combination of heap load and vertical load and horizontal load and inclined load) were collected;the distribution of pile displacement, axial force and bending moment were analyzed. Simulation results show that: slope top loading has little effect on vertical displacement; when the heap load exceeds 200 kPa, the horizontal displacement is greatly affected. Pile axial force decreases with pile burial depth;pile lateral resistance plays a more adequate role in the rock and soil layer. The bending moment of double pile foundation is positive at the top and negative at the bottom. Applied oblique load has obvious p-Δ effect.

Impact of a Low Severity Fire on Soil Organic Carbon and Nitrogen Characteristics in Japanese Cedar Soil, Yamagata Prefecture, Japan

Slash and burn practices are widely used around the globe with different degrees of success which are mostly related to the impact of fire on soil properties. In Japan slash and burn practises, known as Yakihata, have a long history and are still used in Yamagata Prefecture today. The purpose of this study was to determine the impact of a low severity controlled fire underneath Japanese cedar (Cryptomeria japonica) on brown forest soil (Cambisol). Japanese Cedar is the dominant species among plantations in Japan. We measured organic carbon and nitrogen content as well as changes in carbon (δ13C) and nitrogen (δ15N) stable isotope composition in a steep west facing slope under heavy precipitation (~2600 mm/a) and heavy snowfall (~3 to 4 m/a). The accumulation of Ctotal and Ntotal at the bottom of the slopes was remarkably higher at the slash and burned site than in the control forest site. After slash and burn δ15N isotopes in the slope in general became significantly lighter than in the control forest while the δ13C did not show any significant difference between the two sites except at the bottom of the slopes where δ13C was heavier in the forest. The results show that Ctotal and Ntotal values as well as the isotopes ratios of C and N change with decreasing elevation in the forest as well as in the burned site being consistent with leaching and erosion. The changes in soil nitrogen and carbon isotopes at the bottom of the slope appear to be related to the transport of material with different isotopic composition from the upper slope. The effect of the low severity fire (as part of the slash and burn practice) on soil organic carbon and nitrogen movement was enhanced by the steepness of the slopes and the high precipitation of Shonai region.

Cut slope reinforcement technique in open-pit mines

The design and practice in supporting the cut slope of an open-pit mine wereintroduced, in which the high pressure grouting method was used in reinforcing the weak formation inthe slopes. Based on a detailed geological survey of the slope, a theoretical analysis was carriedout, and the design parameters were proposed, where the Tresca or Mohr-Coulomb yield criteria wasemployed. A patent technology, named 'Technology of high pressure and multiple grouting in differentlevels within a single hole', was employed in the construction. Anchor bars were also installed asgrouting proceeds. This method combines anchoring and grouting comprehensively and was foundsuccessful in practice.

Buckling failure analysis and numerical manifold method simulation for high and steep slope: A case study

Buckling failure of layered rock slopes due to self-weight is common in mountain areas, especially for high andsteep slope, and it frequently results in serious disasters. Previous research has focused on qualitatively evaluatingslope buckling stability and rarely studied the whole process from bending deformation to forming landslide. Inthis work, considering the tensile and compressive characteristics of rock, the simulation of high and steep slopebucking failure evolved in Bawang Mountain, was conducted by numerical manifold method. The bucklingdeformation mechanism and progressive failure process of Bawang Mountain high steep slope were studied. Thereliability of the numerical method was verified by the comparison of theoretical calculation and field measurement data. The results show that numerical manifold method can accurately simulate high and steep slopebuckling failure process by preforming interlayer and cross joints. The process of slope buckling deformation andinstability failure can be divided into minor sliding-creep deformation, interlayer dislocation-slight bending,traction by slope toe-sharp uplift, accelerated sliding-landslide formation. Under the long-term action of selfweight, the evolution of slope buckling from formation to landslide is a progressive failure process, whichmainly contains three stages: slight bending deformation, intense uplift deformation and landslide formation.

泸定M_(S)4.5地震不对称高陡谷坡地震动响应

基于2023年四川泸定M_(S)4.5地震实测地震动数据,开展不对称斜坡时频域数据分析。结果表明:1)位于右岸1^(#)监测点的PGA放大系数最大,水平向和竖直向分别为3.16~15.08、4.37;2)Arias强度右岸最大值为2.24 cm/s,左岸最大值为0.79 cm/s,说明右岸地震动响应能量更强;3)斜坡右岸监测点的卓越频率为2~9 Hz,左岸卓越频率为2~17 Hz,地震幅值所呈现出来的能量在水平向比竖直向更为集中。地震动响应在不对称高陡谷坡右岸凸出半岛状斜坡地形比直线形斜坡更为强烈,高位覆盖层的存在会增强地震动响应。

露天边帮开采中充填方式的探讨

针对我国露天边帮开采充填的现状,结合井工开采充填的方式,介绍了矸石充填、膏体充填和高水充填3种边帮充填方式的优缺点,探讨了3种井工开采充填方式应用到露天边帮开采充填的可行性,为露天边帮开采充填设计者提供了一些思路。

基于GEO-Slope方法的危岩体边坡稳定性研究

水能资源富集的西部地区,深切河谷高陡岸坡稳定性问题严重制约了水电建设项目的顺利进行。锦屏一级水电站的高陡边坡稳定性问题十分突出,其左岸1#危岩体边坡即为典型案例之一。1#危岩体边坡为缆机平台边坡,其稳定与否直接关系到缆机平台的顺利开挖。本文运用GEO-Slope方法对其进行了稳定性研究,结果表明,其潜在失稳范围的后缘边界为黄斑岩脉X,底边界为f_(LL2)断层。开挖后该范围块体基本处于极限平衡状态,再加上施工扰动,基本不能自稳,因此建议在开挖前采取相应的支护措施。

Earthquake-induced collapse mechanism of two types of dangerous rock masses

As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially following a strong earthquake, is one of common geological disasters known in rock slope engineering. Therefore, it is important to study the collapse mechanism of dangerous rock masses induced by an earthquake and the analysis approach of its stability. This study provides a simple and convenient method to determine the collapse mechanisms of two types of dangerous rock masses （i.e. cantilever and upright） associated with the definition and calculation of the safety factor, which is based on the flexure theory of a constant-section beam by combining with the maximum tensile-stress criterion to depict the process of crack propagation caused by seismic waves. The calculation results show that there are critical crack depths in each form of the dangerous rock masses. Once the accumulated depth of the crack growth during an earthquake exceeds the critical depth, the collapse will occur. It is also demonstrated that the crack extension amount of each step is not a constant value, and is closely associated with the current accumulated crack depth. The greater the cumulative crack depth, the more easily the crack propagates. Finally, the validity and applicability of the proposed method are verified through two actual engineering examples.

Key Technical Issues of TGP Permanent Shiplock

To solve the high dam navigation issue of a world class project is one of the key technical issues that bring many difficulties upon the Three Gorges Project (TGP). Special requirements exist in the TGP double lane five step shiplock in terms of a general layout of navigation structures, a sedimentation hindrance to navigation, hydraulics of the water conveyance system, treatment of high and steep slopes, the manufacture and technology of both main metal structures and mechanical and electric equipment, all of which have been resolved step by step by means of scientific tests, verification and engineering practice.

高海拔铁路隧道斜井机械化配套与快速施工

为解决高海拔高寒地区斜井施工存在气压低、含氧量低、温差大、严寒干燥等问题,以某高海拔铁路隧道斜井工程为背景,结合围岩等级、断面大小、海拔高度,根据斜井施工机械化配套原则,提出高海拔陡坡长斜井机械化安全快速进洞施工工法,并选配超前支护、钻爆、装运、喷锚支护、衬砌等机械化作业线的成套设备。基于高度机械化的设备配套,提出“快挖、快运、快支”的高效施工技术以及各工序快速衔接工艺。以控制围岩变形为核心,构建一套积极干预加固围岩、注重早期支护并快速闭合的主动支护体系。结果表明:与普通钻爆法施工相比,采用三臂凿岩台车高度机械化配套施工效率高,月最快进尺为180 m,较人工钻爆法施工月进尺为130 m相比提高了近30%,施工质量稳定,作业人员投入少,且拱顶沉降和周边收敛均小于规范要求值,衬砌强度可靠,可实现高海拔小断面隧道“快挖、快支、主动支、快封闭”。

露天矿高陡复杂边坡软弱岩层组“坐落-滑移式”破坏模式研究

边坡稳定性问题随露天矿开采的进行不断突出,而边坡软弱岩层严重影响边坡稳定性。大量工程实例显示,露天矿含软弱岩层组的高陡复杂边坡失稳模式通常为“坐落-滑移式”破坏。为明晰露天矿高陡复杂边坡软弱岩层组“坐落-滑移式”破坏模式的破坏机理,以某露天矿为例,提出一种针对露天矿含软弱岩层组高陡复杂边坡的综合分析方法。研究结果表明:采用工程地质分析、传统极限平衡方法和数值模拟分析相结合的综合分析方法,针对该类型复杂边坡可发挥不同分析方法的优势,较全面地从地质自然环境条件、定性定量方面、应力应变角度分析边坡破坏机理及模式,总结归纳出含软弱层组露天矿高陡复杂边坡“坐落-滑移式”破坏的“坐落-滑移-剪出”三段式破坏特征,为其他类似复杂边坡稳定性的分析和防治提供思路和手段。

石灰石露天矿高陡边坡稳定性计算分析

以西南某石灰石矿高陡边坡为研究对象,根据矿山边坡现状、边坡岩体结构和结构面发育特征因素对“现状边坡”和“终了边坡”进行地质分区,通过岩石室内物理力学试验获得坡体岩石物理力学参数,采用GSI法计算边坡岩体内摩擦角、粘聚力、变形模量和泊松比等参数,评估边坡地质强度特性,采用Morgenstern-Price极限平衡法分三种荷载工况分别计算“现状边坡”和“终了边坡”各分区稳定性系数。经分析,该石灰石矿各地质分区“现状边坡”和“终了边坡”稳定性好,采场边坡参数设计合理,可为矿山扩产安全设施设计和安全生产提供参考。

高边坡下方管廊基坑支护设计方案比选

人工填土高边坡的坡体稳定性差,因其土体未经压实,开挖极易引起坍塌,对周边建(构)筑物的基坑开挖产生严重的安全隐患。根据人工填土高边坡下南宁凤岭管廊基坑开挖的工程地质条件,分析了基坑设计的难点。对钻孔灌注桩、SMW工法桩、钢板桩3种管廊基坑常用的支护形式进行了对比,在综合考虑整体刚度和强度、基坑安全性、费用、施工速度等因素后,最终确定采用具有降低施工成本、可对施工材料重复利用、地下空间资源污染低的SMW工法桩作为该基坑的最佳支护方案。此方案可对今后类似工程的设计施工提供借鉴和参考。

基于无人机3D点云的高陡斜坡岩体结构特征

岩体结构控制着岩质斜坡的变形破坏模式,但传统的结构面信息调查方法存在危险性高、难度大的缺陷。为安全、高效地获取斜坡岩体结构信息,利用无人机摄影技术开展高陡岩质斜坡的测量,构建斜坡岩体的3D点云模型,识别结构面的产状、间距、迹长等岩体结构信息。对湖北秭归卡门子湾滑坡区调查验证,斜坡共发育6组优势结构面,平均间距为0.46~1.01 m,平均迹长为0.82~12.57 m;无人机3D点云获取的岩体结构信息精度满足要求,方法高效、可行;获得的岩体结构信息为斜坡岩体结构模型建立和稳定性评价等工作提供了可靠的数据基础。

点荷载试验在典型露天采场超高边坡工程地质勘察中的应用

夏日哈木镍钴矿山拟建大型超高边坡露天采场,需进行边坡工程地质勘察工作。岩石抗压强度是重要的工程地质参数,如何在青藏高原山区快速获得各类岩石的单轴抗压强度等参数非常关键,尤其是各类难以进行室内压缩试验的风化或蚀变岩石。本次在野外现场采用济南矿岩HDH-1型岩石点荷载仪对矿区内各类岩石进行点荷载试验,并通过前人总结的点荷载强度与单轴抗压强度转换公式计算出了各类岩石的单轴抗压强度及层状(条带状)岩石的各向异性指数。本次点荷载试验克服了昆仑山区岩石测试加工工序复杂、周期较长、成本高等因素,且适用于风化层、蚀变带内不易进行室内压缩试验的岩石,是一种间接测量估算岩石相关强度参数的快捷方法,对以后西部山区的工程地质勘察工作具有较为广泛的借鉴作用。