THE EXTENSIONAL MOVEMENT AND ACTION IN THE SOUTHERN TIBET SINCE HERCYNIAN

THE EXTENSIONAL MOVEMENT AND ACTION IN THE SOUTHERN TIBET SINCE HERCYNIAN     

下坂地水利枢纽工程坝基砂层透镜体的动力特性试验研究

在不同固结状态(σ3 c和kc)下对下坂地水利枢纽工程坝基砂层透镜体的砂土进行了动三轴试验。结果表明:不能用Hard in公式确定偏压固结时的起始动剪切模量G0,G0和τy(最大动应力)均与σ3 c.kc之间有良好的幂函数关系,且对不同固结状态可以归一;动强度dτ/σm′受固结围压σ3 c的影响很小,但随固结比kc的增大而增大;动孔压比ud/σ′m与振次比N/Nf关系曲线为下凹型,不符合Seed提出的孔压模型,可用指数关系来拟合。动应力σd值变化对ud/σm′-N/Nf和ud/σm′-εdr关系影响很小,固结比kc变化对它们有显著的影响;界限残余应变εdr,t受kc的影响较小,但它随σ3 c的增大而增大,当εdr大于εdr,t时呈先快速增长后趋于平缓的变化。     

Test on mechanical behavior of SRC L-shaped columns under combined torsion and bending moment

Investigations of the seismic behavior of steel reinforced concrete L-shaped columns under constant axial compression and cycled bending-shear-torsion load were performed.Six specimens,which considered two parameters,i.e.,the moment ratio of torsion to bending(γ)and the aspect ratio(column length-to-depth ratio,φ),were prepared for the experiment.In this study,the failure process,torsion-displacement hysteresis curves,and flexure-displacement hysteresis curves were obtained.The failure characteristics,mechanical behavior of specimens such as the failure patterns,hysteresis curves,rigidity degradation,ductility and energy dissipation,are analyzed.The experimental research indicated that the major failures of the specimens were bending failure,bending-shear failure and bending-torsion failure as the moment ratio of torsion to bending(γ)increased.The torsion-displacement hysteresis curves were pinched in the middle,formed a slip platform,and the phenomenon of“load drop”occurred after the peak load.The bending-displacement hysteresis curves were plump,which showed that bending capacity of the specimen was better than its torsion capacity.Additionally,the energy dissipation of the specimen was dominated by torsion in the early stage and ultimately governed by the bending moment in the later phase.Test results also indicated that the displacement ductility coefficient and interstory rotation angle of the failure point were less than 3.0 and 1/50,respectively,which means the test specimen performance does not meet the requirement of the Chinese Code for Seismic Design of Buildings(GB 50011-2014)in this respect.     

一种新的地质地貌景观类型—河北省白石山大理岩构造峰林特点及成因

河北省涞源县白石山,在构造上位于NNE向太行山深断裂带的西缘。白石山呈现“双层结构”,山体“底座”为燕山期花岗岩,“顶盖”为中元古界雾迷山组(Jxw)白云石大理岩,形成巨型“顶盘悬挂体”。这里实际上是燕山期以来构造活动带和强震带中的一块“安全岛”,既有产生构造峰林强大的构造应力,又能使峰林很好地保存下来。产状近于水平的白云石大理岩层,因受强大的燕山期主压应力作用,产生两组直立的、规模宏大的NNE和NNW向共轭剪切节理,形成“X型构造”。新生代以来,山体上升,在构造节理的主导下,配合物理风化及部分地表流水作用,逐步发展成为白云石大理岩构造峰林。这是中国地质地貌景观的一种新类型。     

河北省涞水县野三坡国家地质公园：地质遗迹的地质意义和4期节理的导控作用

野三坡国家地质公园位于太行山断隆与燕山“台褶带”的结合部,两构造单元以紫荆关大断裂为界。公园内地质遗迹丰富,其地质内涵是华北地质的精髓。发育4期宏大构造节理,分别与印支期华南板块、燕山期伊佐奈歧板块、华北期太平洋板块和喜马拉雅期印度板块的挤压有关。4期节理,特别是喜马拉雅期南北向“追踪张节理”,对园区构造地貌景观的形成起着关键作用。     

Experimental study on the effects of the moisture content of bituminous coal on its gas seepage characteristics

Moisture content is the main factor affecting the occurrence and flow of gas in bituminous coal and restricts the gas permeability of the coal seam, which affects the effectiveness of gas extraction from the coal seam directly. In order to study the influence of moisture content on the gas seepage characteristics of bituminous coal, this paper focused on bituminous coal from the Xutuan coal mine and used a bespoke laboratory unit called a Gas Flow and Displacement Testing Apparatus (GFDTA). The moisture content of bituminous coal was measured, and the axial and radial gas seepage experiments of bituminous coal under different moisture content conditions were carried out. The average original moisture content (1.3%) and the average saturated moisture content (2.4%) of the bituminous coal sample were obtained. It was observed that, with the increase of time, the original moisture content of the coal decreased with a negative exponential function and the wetting moisture content increased with an Exponential Association function. The gas axial seepage experimental results showed that when the moisture content was lower, the coal adsorbed CH₄; when the moisture content was higher than M_ad, the two fields of gas and liquid are coupled and affect the axial flow of the CH₄, decreasing the moisture content. With higher moisture content, the interaction between the two is more readily evident and the diffusion behavior of the CH₄ has a greater impact on the moisture content. Axial and radial gas seepage experiments, under the same gas pressure, axial pressure, and confining pressure, revealed that with the increase of moisture content, the axial and radial permeability of bituminous coal first increased and then decreased. This phenomenon is analyzed by the water lock effect, the effects of sorption on gas seepage and moisture content on gas adsorption effects. Among them, critical moisture content of approximately 1% exists when the axial and confining pressures are loaded or unloaded at the same time as well as the axial pressure loading or unloading alone. However, the critical moisture content is about 0.5% under confining pressure loading or unloading alone. In addition, in radial seepage experiments, it was observed that the volumetric strain of the coal decreased with the increase in the moisture content.     

河北省白石山中元古代地震遗迹的发现

在河北省涞源县白石山构造峰林游览路线上,中元古界雾迷山组(距今10～14亿年间)第二段地层下部,发现“震动坍塌巨角砾岩”(震积岩)。“巨角砾岩”受两条同沉积期正断层控制,是由两侧断崖上坍塌的岩块瞬时地在水下形成的。这是目前所知最早的震积岩(古地震遗迹)。根据震积岩的规模与两条正断层的断陷程度推测,白石山古地震的强度大体相当里氏6级以上,是华北中元古代地震灾变事件濒发期的具体表现。白石山距古太行山深断裂不足10km,白石山震积岩、同沉积期正断层与古太行山断裂带均呈NNE向延伸,推断当时白石山地区处在古太行山断裂带活动的影响范围内。