采矿外文翻译---受开采影响地表横向剪切变形.docx

翻译部分英语原文ON MINING-INDUCED HORIZONTAL SHEAR DEFORMATIONS OF THE GROUND SURFACEGang Li1, Robert Pquet1, Ray Ramage1 and Phil Steuart1ABSTRACT: Horizontal shear deformations have not been commonly considered in subsidence engineering and risk management practices. This situation is quite different from many other engineering disciplines. This article presents the authors initial findings of case studies from a number of collieries across all NSW Coalfields. The objective of this article is to highlight the significance of a ground deformation mode, that is, horizontal shear, and its implications to subsidence engineering and risk management. A Shear Index is suggested to facilitate studies of mining-induced shear deformations of the ground surface.INTRODUCTIONThis article presents an argument that conventional subsidence parameters specifying horizontal deformations, in particular, horizontal strains (i.e. change in length), are inadequate for subsidence engineering and risk management. The above-mentioned inadequacy can become practically important in areas where only low magnitude of conventionally defined horizontal strains is detectable due to deep cover depths (or relatively low “extraction width-to-cover depth” ratios).Through the preliminary investigation of a number of coals in NSW, the study found there is clear evidence to suggest that the above-mentioned inadequacy is related to a lack of understanding of mining-induced horizontal deformations of the ground surface, in particular, horizontal shear deformations.Despite theoretical definitions found in limited literature on mine subsidence (e.g. 1992), horizontal shear deformations have not been commonly considered in subsidence engineering and risk management practices. This situation is quite different from many other engineering disciplines.HORIZONTAL SHEAR DEFORMATIONSWhen two adjacent cross sections of a stem has a pair of horizontal force perpendicular to stem axis but works in the opposite direction of breaking, and it produces deformation that two section along the lateral force direction of relative rupture occurred. The deformation called shear deformation.Indicators of horizontal shear deformations, as identified by this study, comprise:1. Observed subsidence effects on civil structures indicating influence of shear deformations and significance of this deformation mode in terms of its impacts and frequency of occurrences. The shear effects at a particular site are demonstrated in Figure 1;2. Statistical information suggesting a strong correlation between the shear -affected structures and strip footings, which have less capacity to resist or accommodate horizontal shear deformations as compared with that for other types of footings considered in this study.The analyses show that the transverse shear deformation effect has a significant influence on the thick reinforced concrete slabs and the concentrated load condition;3. Observed patterns of mining-induced surface fractures and deformations (in plan view) suggesting influence of shear, for example, i) en-echelon fractures near chain pillars where shear deformations were active or ii) occurrences of surface wrinkles where the effects of horizontal shear were clearly visible4. Importantly, horizontal shear deformations of ground surface as indicated in 3D survey data obtained from a number of collieries across all NSW Coalfields (to be further discussed).However, rigorous definition, in accordance with the principles of continuum mechanics (e.g. Jaeger, 1969), of horizontal shear strains is not possible using 3D survey data from a straight line of survey points.It follows that if warranted considering the significance of the surface features and their capacity to resist or accommodate shear deformations, the current surveying practices may need to be changed to obtain properly defined horizontal shear strains (or principal strains).To utilise the large amount of subsidence data in existence in the mining industry, an alternative (and approximate) Shear Index is suggested in order to gain an understanding of the general characteristics of mining-induced horizontal shear deformations. This Shear Index is derived based on the component of horizontal movements perpendicular to a survey line or a line of interest. The formula for deriving this index is the same as that for the conventionally defined tilt. Physically, this index reflects angular changes in the horizontal plane but it is not possible to tell what causes such changes, being either shear or rigid body rotation or both. However, the distribution pattern of this index can help to understand the development of shear deformations and to find trouble spots (refer to further discussions presented in the Section below).FURTHER DISCUSSIONS ON HORIZONTAL SHEAR DEFORMATIONSFigure 2 shows the distribution pattern of horizontal movements perpendicular to a survey line across a longwall panel and the corresponding Shear Index as discussed above.Although the site is located in the Hunter Coalfield with shallow cover depths, this case is selected as it provides a clear demonstration of the following observations common to the studied cases from all NSW Coalfields: A complex history of the horizontal movements perpendicular to the cross line (Figure 2a) involving a reversal of movement direction after the extraction face passed the survey site by a certain distance. This distance varied from site to site. Similar findings were reported by Holla and Thompson (1992) and Mills (2001); Indications of horizontal shear deformations (near both solid ribs in this case, as shown by the Shear Index plotted in Figure 2b), noting the reversal in the sense of shearing after the extraction face has passed the survey site. The reversal in the sense of shearing has a potential to enhance the effects of shear deformations, and The occurrences of permanent horizontal deformations.IMPLICATIONSFrom the 3D survey data collected from a number of collieries across all NSW Coalfields, the characteristics (i.e. the magnitude, nature, distribution and timing of occurrences) of the conventionally defined subsidence parameters are compared with those of the following horizontal deformational parameters:(i) Mining-induced horizontal movements perpendicular to survey grid lines, and(ii) The corresponding Shear Index as discussed above.Implications from the findings of the current study so far are summarised as follows.1. Horizontal Shear Deformations There is a need to recognise horizontal shear deformation as a significant mode of mining-induced deformations at the ground surface. Specific attention should be paid to surface features with inadequate shear resistance and to areas with deep cover depths (or relatively low “extraction width-to-cover depth” ratios) where the conventionally defined horizontal strains predicted may suggest low risks.2. Assessment of Subsidence Impacts on Civil Structures Further to Point (1) above, there is a need to recognise the limitations of subsidence models based on conventionally defined horizontal strains and AS 2870-1996 (Standards Australia, 1996) when predicting subsidence impacts on civil structures. Consequently, there is a need to identify areas where changes and improvements to these models are required.3. Civil Structures on Sloping Ground Further to Point (1) above, specific attention should be paid to civil structures on the sloping ground. In this case, there is a potential for enhanced shear deformations due to the participation of down-slope movements. In addition, the performance of any footings to resist or accommodate shear deformations in this environment needs to be investigated and understood.4. Capacity of Surface Features to Resist or Accommodate Shear Deformations This is an area where knowledge has not been clearly established for subsidence engineering and management. The situation here, again, is different from many other engineering disciplines when shear deformations are concerned. There is a need to undertake necessary research into this area.5. Mining-induced Surface Wrinkles Mining-induced surface wrinkles (Figure 3), or compression humps, are one of the significant factors for subsidence impacts on civil structures. Where these deformational features occurred in areas with low predicted horizontal strains according to conventional subsidence models, geological structures were often blamed for their occurrences resulting in unpredicted or higher-than-predicted impacts on civil structures. However, recently conducted field investigations have not been able to provide a clear link between geological structures and such surface wrinkles, while there is a continuing need for an improved understanding of these features to develop effective early warning and risk management systems. The identification of horizontal shear deformations can offer an explanation (Figure 4), additional to geological structures and the conventionally defined compressive horizontal strains, for the occurrences of these deformational features.6. Management of Subsidence-related Risks to Linear Infrastructure Items The results of this study suggest a need to review the adequacy of risk management systems for important linear infrastructure items such as roads, rails, canals or pipelines, if these management systems have been developed based primarily on conventional subsidence models taking into consideration parameters predicted or measured along the lengths of such infrastructure items and/or if the features in questions do not have sufficient capacity to resist or accommodate lateral movements or shear deformations.7. Survey Practices - As discussed above, to obtain properly defined shear strains or principal strains, the survey practices need to be changed. The suggested change is related primarily to the layout of survey grids, for example, 3D surveys of two (or multiple) parallel grid lines separated by an appropriately defined distance.SUMMARYBased on the investigation of the NSW coalfield measurement, this paper analysis the horizontal shear deformation on civil structure influence. This paper research the application of the horizontal shear deformation in the subsidence engineering and risk management system. Finally, the author put forward concerning the horizontal shear deformation field research direction and the prospect of certain.ACKNOWLEDGEMENTThe assistance by NSW Mine Subsidence Board with field investigations and data analysis in relation to civil structures is specifically acknowledged. This article is published with the permission of the NSW Department of Primary Industries. The views expressed in this article are those of the authors.REFERENCESHolla, L and Thompson, K, 1992. A study of ground movement in three orthogonal directions due to shallow multi-seam longwall mining, The Australian Coal Journal, No.38, pp3-13.Jaeger, J C, 1969. Elasticity, Fracture and Flow with Engineering and Geological Applications, pp268 (Chapman and Hall Science Paperbacks).Mills, K W, 2001. Observations of horizontal subsidence movement at Baal Bone Colliery, inProceedings 5th Triennial Conference on Coal Mine Subsidence Current Practice and Issues, pp 99-111.Peng, S S, 1992. Surface Subsidence Engineering, pp162 (Society for Mining, Metallurgy, andExploration, Inc, Littleton, Colorado).Ramsay, J G, 1980. Shear zone geometry: a review. J. Struct. Geol., Vol. 2, pp83-99 Standards Australia, 1996. Residential Slabs and Footings Construction (AS 2870-1996).中文译文受开采影响地表横向剪切变形Gang Li1, Robert Pquet1, Ray Ramage1 and Phil Steuart11 NSW Department of Primary Industries - Mineral Resources摘要：横向剪切变形尚未普遍应用于沉陷工程风险管理。这种情况完全不同于许多其他工程学科。本文介绍了作者在新南威尔士多个煤矿煤田的初步调查结果的案例研究。本文的目的是突出地面变形模型的重要意义，即，横向剪切及其在沉陷工程风险管理中的应用。文中采用抗剪指标来研究受开采影响地表横向剪切变形。简介本文介绍的论点，利用传统的沉降参数指定的水平变形，特别是横向剪切菌株（即长度变化），对于沉陷工程与风险管理系统是不合适的。由于深覆盖层深度（或较低的提取width-to-cover深度”的比率），只有在低程度的传统定义横向拉力是可检测的，上述不足会成为实际监测中的重要影响部分。 作者通过对新南威尔士多个煤矿煤田的初步调查研究发现，有明确的证据表明，上述不足是由于缺乏有关地表受采动影响产生的变形，特别是对地表横向剪切变形的认识。尽管关于横向剪切变形的理论上的定义在有关矿山沉陷的一些文献（例如，Peng，1992）中可以找到，但横向剪切变形尚未普遍在沉陷工程风险管理应用。这种情况是完全不同与其他许多工程学科。横向剪切变形当杆件在两相邻的横截面处有一对垂直于杆轴，但方向相反的横向力作用时，其发生的变形为该两截面沿横向力方向发生相对的错动，此变形称为剪切变形。本文中的主要研究横向剪切变形的指标,内容包括:1 观测沉降在剪切变形和指示意义的变形模式方面对土木结构的影响,考虑到它的影响和出现的频率。如图1剪切效应在一个特定的位置中发生;图 1 土木结构受水平剪切变形的影响2.根据统计资料表明，本研究中认为受剪切效应影响的结构体和地带地基有关，这种地基相对于其他类型的地基具有较少的抵抗或容纳横向剪切变形的能力, 分析表明，横向剪切变形对钢筋混凝土厚板及集中荷载的影响很大； 3.通过观察受采动影响的地面裂缝和变形（从三维角度来看）形式，例如，i）在剪切变形活跃的护巷煤柱附近有雁列式裂缝；ii）在横向剪切变形影响的地表产生清晰可见的表面褶皱。4.重要的是，利用三维测量获得的一系列在的新南威尔士州煤田煤矿的观测数据都表明受开采影响的地表存在横向剪切变形（待进一步讨论）。然而，从严格的意义上讲，根据连续介质力学原理（例如Jaeger，1969），横向剪切应变是不能使用在一条直线上的点的三维测量数据。也就是说，只要合理的考虑地表特征的重要性，以及他们抵制或容纳剪切变形的能力，目前的测量规范可能需要改变以获得横向剪切应变（或主应变）的准确定义。 利用矿山测量中大量的沉降原始观测数据，另一种（或近似）切变指数以便了解具有一般特征受采动影响的横向剪切变形。该剪切指数是由水平运动在观测测线或感兴趣的线上的垂直分量推导得出。该公式推导过程和由常规定义的倾斜得出的是一样的。从物理意义上讲，该指数反映水平角的变化，但是我们不知道它是由剪切或刚体转动引起的，还是两者共同作用的结果。然而，这个指数的分布规律可以帮助我们了解横向剪切变形的发展规律和发现“出错点”（在以下部分进一步讨论中解释）。横向剪切变形进行进一步的讨论图2显示了水平移动在长壁板垂直观测线和上面讨论过的相应的切变指数的分布规律。虽然试验中的观测站是位于浅埋深的Hunter煤田,选取该观测线的原因是由于它可以的论证所有新南威尔士煤田的共同研究特点:一个复杂的垂直于纵线的水平移动曲线图 (图2-a)，该纵轴大小等于以一定距离提取的观测站反向移动距离的平方。这个距离为相邻两观测站之间的距离。类似的研究结果在Holla and Thompson (1992)和 Mills (2001)都有提到；水平剪力变形的大小(在这种情况下，固体两侧板的切变指数标绘在图2 b中),我们发现在提取的切变数据在负方向上通过观测站。在这个意义上的逆转剪切有增强剪切变形影响的作用；该区域内存在永久横向剪切变形。影响分析新南威尔士煤田中一些煤矿的三维测量数据，通过传统意义上的沉降参数特征(即量值大小、特征、分类及其出现的时间)和下列的水平变形参数的进行对比研究:(i)受开采影响的垂直于测量观测线的水平移动；(ii) 上文已经讨论过的相应的切变指数。从当前进行的测量结果，分析研究地表受横向剪切应变的影响，总结如下:1横向剪切变形我们必须认识到横向剪切变形是受开采影响的地表移动变形中一个重要的组成部分。具体要关注抵抗剪切能力不足的地表和在深厚覆盖层深度(或相对较低的“提取width-to-cover深度”比率)的地区,通常利用传统意义上的水平变形进行预测，这些地区的沉陷很小。2土木结构受沉降影响预计进一步在(1)的基础上, 有必要认识到基于传统意义上的水平应变和AS 2870 - 1996(澳大利亚标准协会,1996年)的沉降模型在预计沉陷对土木结构影响时的局限性。因此,当需要使用该模型时，有必要确定模型在哪些地方需要进行改变和改进。3民用建筑受地面倾斜的影响进一步在(1)的基础上,具体应重视位于倾斜地面上的民用建筑。在这种情况下, 由于“下沉倾斜”运动的参与，产生一个增强横向剪切变形的变量。此外, 在上述这种环境中，任意地基抵抗或适应剪切变形的特征都需要研究和分析。4地表抵抗或适应剪切变形的特性能力这一领域知识尚未建立明确的沉降工程和预计体系。这里的情况,当与剪切变形有关时，再一次,不同于许多其他工程学科。因此，非常有必要进行这一领域的研究。5受开采影响的地表褶皱受开采影响的地表褶皱(图3),或压缩隆起,是沉降对土木结构影响的一个重要因素。这些可变形特