倾斜煤层动压巷道围岩应力分布规律的数值分析

针对倾斜煤层巷道围岩应力分布规律问题,建立了不同岩层倾角的数值计算模型,计算分析了倾斜煤层在动压作用下的围岩应力变化过程。通过对计算结果的分析,得知在岩层倾角为30°~40°时,围岩集中应力区域向两帮顶角区域转移;50°~60°时,向下帮底角区域转移;70°~80°时,转移至下帮顶角区域;同时由40°开始,围岩开始显现较强的不对称性,并随岩层倾角的增大快速增大。在动压作用下,围岩不同位置处的应力随动压的增大近似同比例增大;当岩层倾角在10°~50°时,应力提高率处于0.5~2.3;50°~80°时,基本处于0.5左右。针对围岩应力分布的不对称系数分析得知,岩层倾角越大,不对称系数越大;在岩层倾角为30°~80°时,不对称系数在动压作用下基本保持不变,说明在动压作用下围岩应力会持续处于不对称状态。     

煤矿应力异常集中区强矿压防治研究

根据木城涧煤矿三槽西五壁工作面的生产地质条件,采用FLAC^3D三维数值模拟软件,分析了工作面开采过程中的垂直应力,特别是超前支承压力的分布规律,以此划分了应力异常集中区,强矿压危险区域为工作面轨道顺槽前方不规则煤柱的尖角处,垂直应力集中系数达到2.75。利用电磁辐射对上述危险区域进行重点监测,对超过临界预警值的区域,及时采取煤体卸压爆破进行强矿压危险性的卸压解危,并利用电磁辐射检验卸压效果,直至监测指标降至临界值以下,最终确保了工作面的安全生产。     

采掘工作面冲击地压防治

为了能够更好地防治冲击地压,通过分析现有防治冲击地压的技术方法,提出了集束卸压孔防治冲击地压的方法.在巷道周围或工作面顶底板附近,打集束卸压孔,大量取出岩煤,在垂直钻孔的围岩断面上形成一个呈多孔状的弱面,在空间中形成一系列空岩管覆盖或围绕在一定距离的巷道周围或工作面顶底板中.当集中应力作用于巷道围岩时,首先破坏该弱面结构消耗能量,破坏后的该弱面会中断或减弱应力传递,并导致应力集中区向两侧深部岩体转移(采空区或较安全位置),保护巷道不产生或减少两帮挤进和底鼓.当发生地压冲击时,集中应力主要作用于两侧深部煤岩体,从而保护采掘巷道和局部工作面,确保人员设备安全与生产连续进行.     

Identifying and assessing the critical risk factors in an underground rail project in Thailand: a factor analysis approach

Large and complex infrastructure projects involve various risk factors and the successful implementation of such projects depends on effective management of the key risk factors. This paper reviews the literature to identify essential risk variables associated with infrastructure projects. Based on these risk variables, a survey is conducted to isolate and assess the critical risk factors for a mass rapid-transit underground rail project (Chaloem Ratchamongkhon Line), Thailand. Responses obtained within the project organisation are evaluated using principal component analysis to understand the latent structure of the critical risk factors. The variables within the factors are tested to confirm the reliability and validity of the constructs. Finally, nine critical factors with 35 items are extracted after four iterations. Critical risk factors obtained through the factor analysis are assessed to gain better understanding of their importance and impact on project management. The research findings are supported by the perceptions of the senior management within the project organisation, which are also discussed in the paper.     

深部矿体回采过程对巷道变形影响研究

采用FLAC3D程序,对矿体实际开采顺序进行了数值模拟,分析上一分段开采所引起的巷道围岩应力、变形以及塑性区域变化情况,得到了围岩应力、变形及塑性区域变化规律,为巷道稳定性控制提供了理论基础。     

大湾金矿元素组合异常的圈定及找矿方向

通过对云南大湾金矿地球化学特征的研究,认为Au与As、Sb、Hg元素呈正相关关系,尤其与As的相关性较好,与Hg的相关性较弱;Au与Cu、Co、Ni 3种元素呈负相关。用R型因子分析法和元素叠加异常法分别对异常进行了组合异常的圈定,对2种方法进行了对比研究,因子得分圈定组合异常能更准确和直观地反映组合异常浓集中心的位置,但圈定的异常范围较大,无法判断明确的浓集中心,利用异常下限划分出来的异常范围较为真实。     

焊接工字形板梁翼缘对腹板屈曲的影响

在纯弯或纯剪分别作用下的工字形焊接板梁,在弹性范围内腹板屈曲时,翼缘会对腹板起约束作用。通过采用柱稳定特微函数的形函数,用伽勒金法计算表明,其翼缘约束作用的大小,是与翼缘和腹板的尺寸有关。     

Fatigue design of welded very thin-walled SHS-to-plate joints under in-plane bending

The existing fatigue design S–N curve for SHS-to-plate T-joints under in-plane bending is given in the Canadian Standard, CAN/CSA-S16.1-M89, in terms of the classification method. That S–N curve is however based on the class of longitudinally loaded plates with welded non-load carrying attachments, which are different from the SHS-to-plate T-joints. The increased use of welded thin-walled (t<4 mm) tubular joints in the road transport and agricultural industry for applications such as lighting poles, traffic sign supports, truck trailers, swing ploughs, haymakers and linkage graders, means that there is a need to develop fatigue design curves for tubular joints where the tube wall thickness is less than 4 mm. This paper aims to determine fatigue design curves for SHS-to-plate T-joints where the thin-walled tubes have a thickness of less than 4 mm. Tube-to-plate T-joints, made up by welding a square hollow section tube to a plate, are tested under fatigue loading. Constant stress-amplitude cyclic loading is applied to these connections as in-plane bending load. Stress concentration factors (SCFs) have been determined from strain distributions obtained using strain gauge measurements. Analysis of the fatigue test data using least squares method is carried out to determine the design curves of the tube-to-plate T-joints under in-plane bending, for both the classification method and the hot spot stress method. A class of 44 is recommended for the classification method. An S_r._hs–N curve is proposed, with a recommended SCF of 2.0 for the hot spot stress method.     

高层建筑现浇超长地下室应力发展分析

本文以实际工程为背景 ,采用有限元的方法 ,对工程界关心的超长地下室一次性连续浇筑后早期裂缝问题进行数值分析。着重对比应力释放带开设前后 ,地下室墙板、顶板各处应力发展情况 ,并对现浇墙板结构早期的应力发展情况进行分析。     

Analysis of an energy efficient building design through data mining approach

Incorporating energy efficiency and sustainable green design features into new/existing buildings has become a top priority in recent years for building owners, designers, contractors, and facility managers. This paper intends to address why delivery of an energy efficient building is not just the result of applying one or more isolated technologies. Rather, it can best be obtained using an integrated whole building process throughout the entire project development process, which leads building designers to generate a large amount of data during energy simulations. The authors observed that even a simple energy modeling run generated pages of data with many different variables. The volumes of energy modeling data clearly overwhelm traditional data analysis methods such as spreadsheets and ad-hoc queries with so many factors to be considered. An integrated or whole building design process involves studies of the energy-related impacts and interactions of all building components, including the building location, envelope (walls, windows, doors, and roof), heating, ventilation and air conditioning (HVAC) system, lighting, controls, and equipment, which shows why it is so difficult to find the correlation between different systems. The objective of this research is to develop an energy efficient building design process using data mining technology which can help project teams discover important patterns to improve the building design. This paper utilizes the data mining technology to extract interrelationships and patterns of interest from a large dataset. Case study revealed that data mining based energy modeling help project teams discover useful patterns to improve the energy efficiency of building design during the design phase. The method developed during this research could be used to guide designers and engineers through the process of completing an early design energy analysis based on energy simulation models.