顺层路堑边坡锚杆支护稳定性的有限元模拟分析

基于理想弹塑性本构模型和Drucker-Prager准则,运用ANSYS软件和有限元数值模拟技术,建立了顺层岩体边坡的有限元分析模型。结合沪蓉国道主干线宜昌至恩施公路白氏坪-榔坪段顺层路堑高边坡工程实例,对顺层岩体路堑边坡布设锚杆支护前后的应力、变形和稳定性进行了模拟分析。分析比较表明,锚杆支护结构可以减小边坡临界状态下的最大位移、增大最危险接触面的摩擦力和提高边坡的稳定性系数,从而能有效地提高边坡的稳定性以防止顺层滑坡的发生。     

山西腰站矿区ZK6004孔烧钻事故的处理

山西腰站矿区施工的ZK6004钻孔,设计孔深1450 m,地层复杂,而且全孔漏失,极易发生烧钻事故。就该孔连续发生的2次烧钻事故,进行了事故原因分析、处理方法的经验介绍。2次烧钻事故的处理过程中,根据实际不同情况,分别采用了掏眼法和冲砸法。这是深孔烧钻事故处理新方法、新尝试。同时总结了漏失深孔烧钻事故的预冲孔经验及预防措施。对于今后在复杂漏失地层深斜钻孔的施工有一定的借鉴价值。     

路基沉降监测中几种监测方法的应用

某高速公路工程是北京地区高速公路修建中地质条件复杂的工程之一,我们对本工程重点路段进行了施工期和工后变形监测。在整个工程监测中我们采用了横剖测试法、沉降板测量法和分层沉降法等几种监测方法进行了路基沉降监测。这几种监测方法也都体现出了不同的特点,下面对几种监测方法在工程应用中的区别、特点进行分析总结,希望对类似工程的方法选择和设计优化有所帮助。     

岩石切削机理模型分析及实验研究

切削机理模型是研究岩石钻进切削过程中的切削力以及切削热的基础。在分析岩石切削机理模型的基础上,基于摩尔理论和裂纹扩展理论,分析中硬岩石切削状态,认为在中硬岩石切削过程中岩石存在着脆性切削和延展性切削2种方式,在此基础上得到新的中硬岩石切削机理模型。以砂岩、大理岩和花岗岩为钻进对象,开展微钻实验研究。结果表明：切削过程为岩石在刀具的扭矩和推进力作用下发生破坏,导致小岩屑、大切屑不断循环产生的过程,小大切屑形成主要源于岩石挤压变形和裂纹生成扩展。实验结果与岩石切削机理表现出较好的一致性。     

Robust algorithms for polyhedral modelling of fractured rock mass structure

This paper presents robust algorithms for application in polyhedral modelling of rock mass structure based on discrete fracture networks. The algorithms improve the robustness of current polyhedral modellers to challenging or degenerate geometries and geometrical errors. These issues are inevitably encountered when the fracture network realisations incorporate large numbers of fractures, or regions of densely packed fractures are modelled, or when the number of fracture network realisations interrogated is large. Several stages in the polyhedral modelling process which are sensitive to geometrical errors are reviewed and algorithms which are robust and capable of handling topological errors in the input fracture network geometry are presented.     

水力内割刀在中国东部海区科学钻探套管卡阻事故处理中的应用

中国东部海区科学钻探CSDP-02井完钻井深2843.18 m。为后续开展相关科研工作,完井后要进行扩孔钻进施工。扩孔前需起拔井内φ114 mm套管,由于套管在井内时间较长,井壁失稳,套管起拔遇卡,无法正常起出。采用水力内割刀工艺,分段割取遇卡套管,提高单次起拔遇卡套管长度,经济、高效地解决了该井套管卡阻事故。本文结合工程实例,对水力内割刀的使用方法及要点进行了阐述。     

复合排渣钻进技术在松软突出煤层中的应用

分析了复合排渣钻进技术的原理、特点和工艺参数,介绍了在松软突出煤层中复合排渣钻进技术的配套设备和应用情况。实践表明,复合排渣钻进技术在松软突出煤层钻进中取得了较好的应用效果。     

Discrete element modeling of tool‐rock interaction I: rock cutting

Tool‐rock interaction processes can be classified as indentation or cutting depending on the direction of motion of the tool with respect to the rock surface. The modes of failure induced in the rock by an indenting or a cutting tool can be ductile and/or brittle. The ductile mode is associated with the development of a damage zone, whereas the brittle mode involves the growth of macrocracks. This is the first part of a series of two papers concerned with an analysis of the cutting and the indentation processes based on using the discrete element method. In this paper, numerical simulations of the cutting process are conducted to reproduce the transition from a ductile to a brittle failure mode with increasing depth of cut, which is observed in experiments. The numerical results provide evidence that the critical depth of cut d _* controlling the failure mode transition is related to the characteristic length ? = (K_Ic ∕ σ_c)² with K_Ic denoting the material toughness and σ_c its unconfined compressive strength. The nature of frictional contact between the cutter face and the rock in the ductile failure mode is also examined. It is shown that the inclination of the total cutting force is controlled by a multi‐directional flow mechanism ahead of the cutter that is related to the formation of a wedge of failed material, intermittently adhering to the cutter. As a result, the inclination of the total cutting force varies with the rake angle of the cutter and cannot be considered an intrinsic measure of the interfacial friction between the cutter and the rock. Copyright © 2012 John Wiley & Sons, Ltd.     

矿山地质环境治理中坚硬岩石削坡方法比较和优化

对各种岩性的山体进行削坡减载是矿山地质环境治理项目中的重要工程。以江苏省某地矿山环境治理项目为例,对高边坡坚硬石体削坡的“露岩爆破法”、“膨胀剂破碎法”、“二氧化碳致裂法”、“机械破碎法”4种方法进行了比较和优化,在分析了该工程的施工重点、难点的基础上,选用“二氧化碳致裂法”施工,取得了良好的效果。详细介绍了工程的施工工艺、施工过程等,总结了相关经验,对用“二氧化碳致裂法”施工进行了进一步的思考。     

福建省永安市西洋镇2.5a生人促阔叶林与伐前林分的对比评价

福建省永安市西洋镇2.5 a生人促阔叶林分平均胸径、树高、密度、单位面积蓄积量和平均年生长量分别为2.0 cm、1.8 m、19 533 株/hm2 、7.0 m~3/hm~2和2.80 m~3/(hm~2·a),乔木层物种丰富度R、多样性指数SW、均匀度E和生态优势度ED分别为33、2.93、0.62和0.21,林分相对直径分布范围0.25-3.00,直径分布为反J型,表现为异龄林特征.35 a生的伐前林分平均胸径、树高、密度、单位面积蓄积量和平均年生长量分别为13.6 cm、10.5 m、1 185 株/hm2 、101.3 m~3/hm~2和2.89 m~3/(hm~2·a),乔木层物种丰富度R、多样性指数SW、均匀度E和生态优势度ED分别为24、3.72、0.81和0.10,林分相对直径分布范围0.44-2.50,直径分布为反J型,表现为异龄林特征.