Investment risk analysis of China's wind power industry based on pre-assessment matrix

Wind energy is a clean and sustainable energy, and wind power does not rely on fossil fuels. So there is no fuel price risk, and it, of course, does not include the environmental costs, such as carbon emissions. Because of these unique advantages, wind power has gradually become an important part of the strategy of sustainable development in China. Now with the growing voices on global greenhouse gas emission reduction, and as a clean and efficient energy, wind power has huge potential in combating climate change, energy security pressures and the needs for energy. Wind power in China began to develop from the 1980s. In the first 20 years, the speed of development was slow; but since 2004, it has had an extremely rapid growth.This paper, in order to study the development mechanism of China＆amp;amp;amp;#39;s wind power industry, investigated and analyzed the status quo of wind power industry in China, and then found that （1） the development trend of wind power industry in China appears exponential growth; （2） China＆amp;amp;amp;#39;s installed capacity of wind power is still smaller than that os some other countries; （3） new subsidy policies bring developing opportunities to wind power industry in China; （4） the sectors of wind power industry are in unbalanced growing; （5） the owners of proposed wind farms are too optimistic though the built wind farm had many problems. In addition, by using the methodology of Game Theory, this paper has also constructed the matrix of pre-assessing risks of China＆amp;amp;amp;#39;s wind power industry to further discuss the potential risk factors within China＆amp;amp;amp;#39;s wind power industry as risk factors of wind farm construction, risk factors of production of wind turbines, risk factors of parts and components manufacturing industry under risk indicators like R＆amp;amp;amp;amp;D, patents, the domestic policy, the international policy, the quality of products and the market regulation, in order to provide a scientific assessment and self-assessment tool for investors or implementers, and also to promote the further development of the wind power industry.

NEURAL NETWORK ASSESSMENT OF ROCKBURST RISKS FOR DEEP GOLD MINES IN SOUTH AFRICA

ＮＥＵＲＡＬＮＥＴＷＯＲＫＡＳＳＥＳＳＭＥＮＴＯＦＲＯＣＫＢＵＲＳＴＲＩＳＫＳＦＯＲＤＥＥＰＧＯＬＤＭＩＮＥＳＩＮＳＯＵＴＨＡＦＲＩＣＡ①ＦｅｎｇＸｉａｔｉｎｇＣｏｌｅｇｅｏｆＲｅｓｏｕｒｃｅｓａｎｄＣｉｖｉｌＥｎｇｉｎｅｒｉｎｇ，Ｎｏｒｔｈｅａｓｔ...

AN EXPERT SYSTEM ON ASSESSING ROCKBURST RISKS FOR SOUTH AFRICAN DEEP GOLD MINES

Expert systems are methods that can cope with rock engineer’s expertise effectively.An expert system on assessing rockburst risks for South African deep gold mines is described.Expertise was represented by rules, frames and mathematical models integratively. About 950 rules was built in the knowledge base, which can be learned by the suggested learning algorithm. A new uncertain reasoning algorithm was proposed. According to the features such as depth below surface, energy release rate (ERR), excess shear stress (ESS), geological structure, face angle with structure, distance from structure, extent of mining, mining type, width of bracket pillar, stope width, local support, regional support and gully support, rockburst risk is assessed either "Low", "Moderate", "High" or "Severe". A computer program system was developed by Turbo Prolog. The results of testing cases show its applicability of the system.

Studies on the evolution process of rockbursts in deep tunnels

This paper focuses on the evolution processes of different types of rockbursts occurring in deep tunnels. A series of laboratory tests and in-situ monitoring in deep tunnels excavated by tunnel boring machine （TBM） and drill-and-blast （D＆B） method have been conducted to understand the mechanisms and processes of the evolution of different types of rockbursts, including strain rockburst, strain-structure slip rockburst, immediate rockburst and time-delayed rockburst. Three different risk assessment methods are proposed to evaluate the intensity and potential failure depth of rockbursts. These methods can be applied before excavation and the results can be updated according to the real-time information during excavation. Two micro-seismicity based real-time warning systems have been established for predicting various intensities ofrockbursts, such as slight, moderate, intensive and extremely intensive rockbursts. Meanwhile, the probability and intensity of the rockburst are also given. The strategy for excavation and support design has been suggested for various intensities of rockbursts before excavation. The strategy for dynamic control of the rockburst evolution process is also proposed according to the monitoring results. The methodology has been successfully applied to rockburst risk reduction for deep tunnels at Jinping II hydropower project. The results have illustrated the applicability of the proposed methodology and techniques concerning rockbursts.

A semi-quantitative coal burst risk classification system

Safety is the highest priority in the mining industry as underground mining in particular poses high safety risks to its workers. In underground coal mines, coal bursts are one of the most catastrophic hazards, which involves sudden and violent dynamic coal mass failure with rapid ejection of the broken material into the mine workings. Despite decades of research, the contributing mechanisms of coal bursts are still not completely understood. Hence, it remains challenging to forecast coal bursts and quantify their likelihood of occurrence. However, a range of geological and geotechnical factors are associated with coal bursts and can increase the coal burst proneness. This paper introduces a semi-quantitative coal burst risk classification system, namely, BurstRisk. Based on back-analysis of case histories from Australia, China and the United States, BurstRisk classifies the coal burst risk into three categories:low, medium and high risk. In addition, it allows mining engineers to modify the weighting of the selected factors based on specific conditions. The risk classification charts introduced are for both longwall retreat and development sections of long-wall mining operations. This paper also provides a set of risk management strategies and control measures for effective coal burst mitigation.

Rockburst risk control and mitigation in deep mining

It is important to understand and manage rockburst challenges in deep mining operations.This paper presents a systematic study of rockburst risk in underground mining,offering a detailed examination of influencing factors,risk assessment,and various control and mitigation methods.The complexities of rockburst phenomena are explained by examining factors that lead to the occurrence of rockbursts.A rockburst risk assessment using a bow-tie analysis is conducted,which provides insights into both risk evaluation and proactive control and mitigation systems.The core of the paper presents a comprehensive array of rockburst risk control and mitigation methods,which range from controls to reduce rockburst hazard,and excavation vulnerability,to controls and mitigations to reduce exposure.Strategic engineering control methods,including mine design and mining sequencing,are discussed.Tactical engineering control measures,such as ground pre-conditioning and rock support,are scrutinized,along with administrative controls like evacuation and re-entry protocols and the use of mechanized equipment.A multiple-line defense system is advocated for rockburst risk management to address the uncertainties involved in the process.Finally,emerging technologies and innovations as well as challenges are discussed,providing a roadmap for continued advancements in rockburst risk management in the future.This work serves as a valuable resource for mining professionals,researchers,and policymakers seeking a comprehensive understanding of rockburst risk management in deep mining.

动载扰动诱发巷道冲击的风险性分析

巷道冲击地压发生机理与风险性评估问题,对不同区域应力场中的巷道围岩分区能量释放规律进行分析,考虑动载事件扰动,建立了始态应力场、动载事件产生的瞬态应力场与巷道围岩破坏之间的力学联系,提出了动载事件扰动下的终态巷道围岩塑性区边界计算方程,阐述了动载事件与始态应力场共同作用诱发冲击地压的机理,并对不同因素变化下的巷道冲击风险性进行了分析,以震动事件发生角为指标对动载事件发生的不同区域进行了风险强度的划分。研究结果表明:区域应力场不均匀程度的增大使得巷道围岩系统在扰动平衡后的能量释放量增大,且能量释放的主要区域为区域应力场的最大围压方向;巷道冲击地压是巷道围岩受始态应力场与动载事件的瞬态应力场2者共同作用的结果,动载事件的影响会使得巷道围岩系统的终态应力场产生偏转,而围岩协调所释放的能量是冲击产生的主要原因;当始态应力场处于蝶形风险区时,受动载事件影响后的巷道冲击风险性更大,且动载事件的有效释放能量的增大、震源距离的减小与横波能量占比的增大会使得巷道冲击风险性随之增大;震动事件发生角影响着巷道冲击风险性,当动载事件发生在强风险区与次强风险区时,微小的动载事件也极易诱发冲击地压,巷道冲击风险性较高;当动载事件发生在弱风险区时,较大的动载事件也不易引起冲击地压,巷道的冲击风险性较低。

冲击地压煤层智能开采关键技术研究与实践

如何实现深部冲击地压煤层智能安全高效开采是煤炭开采面临的一项重大工程技术难题。该问题的核心内涵在于冲击地压煤层开采的智能化、无人化和本质安全化,通过煤岩冲击风险的智能精准感知与预警,以及采掘工程的自适应与自优化,形成智能防冲控采技术,实现由工程致灾向工程防灾、工程减灾的根本转变。通过开采源头设计、顶板区域压裂、局部靶向治理、强化巷道支护等措施为冲击地压煤层安全高效开采创造低应力环境和巷道安全空间。在此基础上,开发融合静态地质、动态监测、工况环境、人员定位、生产组织、历史数据等信息的大数据分析软件平台,以及融合冲击地压决策信息的智能化开采控制系统,将防冲信息源转化为智能开采控制源,形成了“低压快推,中压慢采,高压停产”的柔性智能推采新模式。通过现场应用表明,在智能防冲控采区,工作面及巷道矿压显现程度更小,煤岩能量释放更稳定,有利于冲击产能的合理释放。

冲击矿压的声发射监测技术研究

煤岩体的破坏伴随着声发射现象,通过分析煤岩体损伤破坏与声发射之间的耦合关系,论述了利用声发射评价冲击矿压危险的可行性,提出了冲击矿压危险性评价的声发射指标的表达方式、临界指标的确定以及危险等级的划分。实验室测试了某冲击矿压矿井煤样破坏过程的声发射特征,为现场应用提供参照。最后分析了波兰ARES声发射系统在冲击矿压矿井中的应用效果与存在的问题。

煤层定点水力压裂防冲的机制研究

为实现在掘进或回采前对冲击危险煤层的一次性卸压,达到区域防冲的目的,提出了煤层定点水力压裂技术。为了从理论上说明煤层定点水力压裂技术防治冲击地压的可行性和有效性,首先,通过建立煤层压裂力学模型,从定性和定量两方面分析煤层定点水力压裂防冲的机制,认为煤层压裂通过增阻和降能2方面实现冲击地压的防治;提出了基于压裂效能指数In的压裂防冲效果评价方法以及关键冲击块临界体积的估算公式,为煤层压裂施工参数的选择提供参考;最后,在华丰煤矿1412工作面成功应用该项技术,从现场观测、管路压力、微震事件和应力变化4方面验证了煤层定点水力压裂技术防治冲击地压的效果。

冲击危险评价的相对应力集中系数叠加法

冲击动力灾害是关乎矿井能否安全稳定生产的主要因素,目前越来越多的矿井需要在采掘工作面设计阶段确定冲击危险等级与区域,迫切需要发展科学、精确、定量、便于技术人员操作的冲击危险早期评价预警方法。为了解决冲击显现无法用现有强度准则进行表述、不同应力无法标量叠加的问题,提出了冲击危险评价的相对应力集中系数叠加法,将某一待分析区域内影响冲击矿压发生的某因素引起的最大主应力与自重应力的比值,称为相对应力集中系数分量,各分量的乘积为该区域的相对应力集中系数。将影响冲击矿压的因素从载荷特性上分为静载荷和动载荷,从对应力影响效果上分为增压型与减压型,给出了影响冲击的主要动载因素,以及相对应力集中系数计算方法。发生过冲击矿压的矿井利用冲击区域的总相对应力集中系数作为临界指标,未发生冲击的矿井利用临界应力与自重应力的比值作为临界值,根据相对应力叠加系数与临界值的比值对冲击危险等级进行了划分。现场应用表明,相对应力集中系数叠加法与监测冲击危险区域与等级具有较高一致性。

影响冲击地压危险性评价结果的Ⅱ类开采技术因素研究

针对目前冲击危险性评价方法的不足,提出了II类开采技术因素,并揭示了该类因素诱发煤岩震动异常并激发灾害发生的内在规律。结果表明,工作面推进度与高能震动事件频率成正比,推进度变化梯度与高能震动事件能量大小成正比,大的变化梯度将增加冲击地压突发的风险;煤层卸压爆破针对巷道两帮冲击启动区,爆破后7~18 h内是解危措施发挥作用的主要时段;巷帮扩修使得围岩从原有的相对稳定变为不稳定状态,扩修进尺过快显著影响煤岩震动异常;工作面停产后恢复生产时期,各能级的微震事件急剧上升,且伴随高能事件发生的危险。II类开采技术因素临时介入,打破原有平衡状态,使得煤岩宏观调整,微观破裂突然无序,激发煤岩冲击事件发生。

基于动静应力分析的复杂工作面冲击危险评价

为在回采前定量评价复杂条件工作面冲击危险等级及划分冲击危险区域,基于冲击矿压发生的动静叠加诱冲原理,以济宁三号煤矿复杂条件工作面为工程背景,提出了基于动静应力分析的冲击危险评价方法。实验室试验研究表明,煤体动力破坏的临界应力与煤的单轴抗压强度密切相关,根据煤体单轴抗压强度,确定了济宁三号煤矿复杂工作面冲击临界应力为70MPa。采用FLAC3D数值软件,研究了工作面原岩应力与采动支承压力分布规律,得到了静载应力分布曲线。探讨了工作面过断层期间的应力演化规律,根据断层至工作面的距离,将采动作用下断层附近支承压力对冲击影响程度分为4级,即小于10 m时为塑性变形区,10~20m为冲击弹性区,20~50m为应力叠加区,大于50m为原始应力区。采用理论分析,计算了坚硬顶板破断来压的能量释放规律,工作面基本顶破断步距在50m时,释放能量达到105J,对应动载应力为10MPa。基于动静载应力水平,给出了冲击危险等级评价与划分标准,将冲击危险性分为4级,动静载最大叠加应力小于50 MPa为无冲击危险;50~70MPa为弱冲击危险;70~105MPa为中等冲击危险,大于105 MPa为强冲击危险。对123下04工作面冲击危险进行了评价与分区,与现场微震监测结果具有较高的一致性,为工作面的安全回采提供了支持。

煤岩动力系统失稳机理

为了计算不同冲击危险程度煤岩体的具体影响尺度,实现煤矿冲击地压的针对性预防和治理,提出了"煤岩动力系统"的概念,构建了"煤岩动力系统与冲击地压显现关系"模型。基于爆破理论和Mises屈服强度准则,提出了"煤岩动力系统"各区域尺度计算方法并建立了相应的评价指标体系。根据煤矿已发生冲击地压和"高能量"微震事件的震源位置和能量值,确定煤岩动力系统"动力核区"、"破坏区"、"损伤区"和"影响区"等各区域尺度的具体影响范围,判断不同尺度范围内煤岩体的冲击危险程度。将煤岩动力系统各区域尺度计算方法在老虎台煤矿进行了准确性验证,表明该方法具有较高的可信度和实用性,可以广泛应用在矿井冲击地压的预测与危险性评价工作中。

基于数据挖掘的深部采场岩爆知识的自动获取

将岩石力学和人工智能相结合 ,提出了深部采场岩爆风险估计知识自学习的一种新方法·它利用数据挖掘的方法从岩爆实例数据中挖掘出知识 ,并在此基础上建立了岩爆风险估计的智能系统·从而可以根据获得的现场测试和监测资料 ,综合估计深部采场因开采而诱发的岩爆风险·

吉林省道清矿北斜井南平峒煤层冲击地压危险性数值模拟

通化矿业(集团)公司道清煤矿地质构造复杂,且已经进入深部开采阶段,煤体采动所形成的矿压对安全生产造成较大威胁。为预测该矿北斜井南平峒煤层冲击地压危险性的程度,对其煤层进行冲击地压危险性数值模拟,分析了煤层在自重应力场和构造应力场下水平应力、垂直应力、XY剪切应力大小及分布规律,得出应力集中区出现在F3号逆掩断层与煤层交汇处,即此处冲击地压危险性程度相对较大,开采时应注意防范,确保矿井安全开采。

深部开采诱发的岩爆及其防治策略的研究进展

深部开采诱发了严重的岩爆。在南非的深部金矿，67％的死亡和30％的受伤者与岩爆和岩崩有关。本文给出了目前岩爆机理和风险估计研究的主要进展、现场监测矿震的主要手段和防治岩爆的几种主要的有效措施。

基于贝叶斯判别法的工程岩爆危险评估与预测

基于岩爆在工程中的特点和岩爆烈度分级预测理论,运用贝叶斯判别原理,确定了工程岩爆危险评估与预测的贝叶斯判别分析法。通过辨别对岩爆产生作用的因子,拣选了围岩最大切向地应力/岩石单轴抗压强度(σθ/σc),岩石单轴抗压强度/岩石单轴抗拉强度(σθ/σt),弹性能量指数(Wet)作为贝叶斯判别分析模型的判别因子,从而进行岩爆误判概率的计算与岩爆危险评估与预测。以贵州省江口至都格、江口至瓮安高速、杭瑞高速等公路工程实例作为学习样本,进行训练判别,通过与现场观测、聚类分析、人工神经网络方法(NN)的预测进行对比,结果发现与训练模型回判的结果一致,验证了贝叶斯判别准则的可行性与可靠性,其对岩爆危险的准确分级和预测,具有较高的工程应用价值。

岩爆危险性评价的变权物元可拓模型

为客观评价岩爆危险性,将物元理论与变权理论结合,构建了变权物元评价模型。首先,对指标数据规则化处理,解决传统物元模型自身局限性;其次,基于变权理论确定评判指标权重,避免评价过程中的主观性,同时使得被评价对象主动参与综合评判;第三,以非对称贴近度代替传统模型中的最大隶属度;最后,通过物元等级变量特征值的计算结果对样本等级进行评定,以权重及特征值对指标的敏感性确定影响评价结果的关键性指标。以甲玛矿为例,计算结果显示该矿为弱岩爆等级,且偏向于无岩爆,与现场实际情况吻合,与已有评判结果基本一致;倾向性指数、应力指数为敏感性指标,应力系数为一般敏感性指标。

深部硬岩矿山岩爆风险防控技术研究进展

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