复合填料一维冻胀量数值模拟分析

复合填料是以废铸砂、粉煤灰、聚苯乙烯颗粒（EPS）、水泥和水为原料,拌合后形成的一种轻质填筑材料。其中,EPS颗粒含量适当时,能减少或消除复合填料的冻胀和融沉,可作为季节性冻土区的路基填料。假设复合填料中除EPS颗粒外的骨料颗粒、孔隙冰为刚性介质,同时考虑EPS颗粒变形和填料孔隙变形对复合填料冻结过程的影响,在已有的冻土水热耦合分离冰模型的基础上,得到考虑EPS颗粒变形影响的饱和填料一维冻结水热耦合控制方程,进而预测填料的冻胀量。与室内模型试验结果对比表明,本文模型可用于该种具有弹性颗粒复合填料的冻胀量模拟,为工程中冻胀量预测提供依据。     

Seismic analysis of a building block

This paper reports on the study of the seismic response of an urban building block located in Faial, a town of the Horta Island of the Azores, Portugal. The work fits within the framework of studying strengthening schemes suitable for the reconstruction process of a town damaged by an earthquake action and includes numerical modelling of all the building blocks with calibration of material and structural parameters based on ambient vibration tests. The study aims at understanding a number of issues that are likely to influence the global behaviour of the block and the local response of individual buildings, namely the group effect of adjacent constructions, the in-plane stiffness of floors and/or roofs and the presence of possible localized strengthening interventions in selected parts of the block.     

Sedimentary facies of the subaqueous Changjiang River delta since the late Pleistocene

The sedimentary facies of the subaqueous Changjiang(Yangtze) River delta since the late Pleistocene was studied based on lithology and foraminifera analysis for two boreholes,CJK07 and CJK11,along with14C dating.Four sedimentary facies were identified,namely fluvial,tidal flat,offshore,and prodelta facies.The fluvial sedimentary facies is comprised of fluvial channel lag deposits,fluvial point bar deposits,and floodplain deposits,showing a fining-upward sequence in general with no benthic foraminifera.A layer of stiff clay overlies the fluvial deposits in core CJK07,indicating a long-term exposure environment during the Last Glacial Maximum(LGM).During the postglacial sea-level rise around 13-7.5 cal ka BP,the tidal flat facies was deposited in core CJK11,characterized by abundant silt-clay couplets.Euryhaline species dominate the subtidal flat foraminiferal assemblages,while almost no foraminifera was found in the intertidal flat.The offshore environment was the major sedimentary environment when the sea level reached its highest level around 7.5 cal ka BP,with a maximum accumulation rate of 10 mm/a found in core CJK11.Prodelta sediments have been deposited in core CJK11 since ~3 cal ka BP,after the formation of the Changjiang River delta.The difference in sedimentary facies between core CJK07 and CJK11 is due to their location: core CJK07 was in an interfluve while core CJK11 was in an incised valley during the LGM.Furthermore,AMS14C dating of core CJK07 shows poor chronological order,indicating that the sediments were reworked by strong tidal currents and that sediment deposited since ~7.7 cal ka BP in core CJK07 was eroded away by modern hydrodynamic forces caused by the southward shift of the Changjiang River delta depocenter.     

塔里木东南缘阿克塔什塔格地区古元古代壳源碳酸岩的特征及其地质意义

塔里木盆地东南缘的阿克塔什塔格地区,变质基底杂岩中发育火成碳酸岩侵入体,呈似层状侵入于米兰岩群和新太古代TTG花岗片麻岩中。碳酸岩主要由方解石(45%~90%)、透辉石(15%)和含量不等的石英、长石等矿物组成,可见少量金云母、方柱石,矿物组成较为简单。常量元素中Fe、Mg、Mn、Ti、P等元素低于世界已知幔源碳酸岩10个数量级之上,而Si、Al含量较高;微量元素富集大离子亲石元素Rb、Th、K和轻稀土元素,亏损高场强元素Nb、Ta、Sr、Ti, 并且稀土总量仅为(25.74~63.01)×10-6,锆石Th/U比为0.04~0.36。上述特征明显有别于幔源成因的碳酸岩,可能指示米兰岩群大理岩在古元古代的深熔作用,即由米兰岩群中的大理岩在古元古代深熔作用条件下形成。挑选其中的锆石利用U Pb SHRIMP法测年,获得年龄为(1 931±18) Ma。该碳酸岩体的发现不仅丰富了壳源碳酸岩的成因类型,也暗示塔里木克拉通的新太古代基底变质岩在古元古代末期发生过深熔作用和混合岩化,是塔里木克拉通对全球哥伦比亚超大陆的汇聚事件的响应。     

Bending of Jets in the QSO NRAO 530

We present radio images of NRAO 530 on scales ranging from pc to kpc. The observations include the EVN at 5 GHz, the VLBA at 1.6, 8.6 and 15 GHz, the MERLIN at 1.6 and 5 GHz, and the VLA at 5, 8.4, 15, 22, and 43 GHz. The VLBI images show a core-jet structure with an oscillating trajectory on a scale of about 30 mas north of the strongest compact component (core). Superluminal motions are detected in five of the jet compo-nents with apparent velocities in the range of 13.6 to 25.2c. A new component is detected at 15 GHz with the VLBA observations, which appears to be associated with the outburst in 2002. Significant polarized emission is detected around the core with the VLBA observationsat 15 GHz. Rapid variations of the polarization intensity and angle are found between the epochs in 2002 and 2004. On the kpc-scale, a distant component (labelled as WL) located 11 arcsec west (PA=-86°) of the core is detected beyond the core-jet structure which ex-tended to several hundreds of mas in the north-west direction (-50°). A significant emission between the core-jet structure and the WL is revealed. A clump of diffuse emission (labelled EL, 12 arcsec long) at PA 70° to the core, is also detected in the VLA observations, suggest-ing the presence of double lobes in the source. The core component shows a flat spectrum,while the distant components WL and EL have steep spectra. The steep spectra of the distantcomponents and the detection of the arched emission suggest that the distant components are lobes or hot-spots powered by the core of NRAO 530. The morphologies from pc-to kpc- scales and the bending of jets are investigated. The observed radio morphology from pc to kcp appears to favor the model in which precession or wobbling of the nuclear disk drives the helical motion of the radio plasma and produces the S-shaped structure on kpc scale.     

海上低渗透油田特点及开发策略探讨

目前海油低渗探明储量和低渗的产量分别占海油总探明储量和总产量比例虽然小,但在海油实现5 000万t年产后稳产阶段所起的作用将会越来越大。对于海上10～50 mD之间的一般低渗为主要考虑的勘探开发对象,当渗透率是5～10 mD之间的特低渗油田时需要优选出构造相对简单、储层比较连续的区块开发;对于复杂断块特低渗透油田和小于5 mD的超低渗油田,在目前海上经济技术条件下暂不具备勘探开发条件。在海上低渗透油田开发中需考虑压裂、注水的综合应用,尽量采用水平井和分支井开发,并且在开采过程中注意低渗储层的保护。     

乾安县40年气候变化的分析

利用东北地区月平均气温、降水量、蒸发量等资料,计算了宁夏季气温和降水的相关系数,表明东北地区西部复季气温与降水量呈显著负相关.从年代际变化的分析中得知,20世纪90 年代暖干趋势明显,其中以乾安最为突出.分析乾安及其邻近测站蒸发量的年代际变化,表明乾安的夏季蒸发量上升趋势明显,并远大于其他测站,对环境的不良影响加重,而存下垫面条件较好一些的区域,夏季蒸发量呈下降趋势.乾安县未来复季气温仍为上升趋势,降水量存总体平均值之下呈旱.涝交替变化.     

Ultrasonic method for measuring water holdup of low velocity and high-water-cut oil-water two-phase flow

Oil reservoirs with low permeability and porosity that are in the middle and late exploitation periods in China’s onshore oil fields are mostly in the high-water-cut production stage. This stage is associated with severely non-uniform local-velocity flow profiles and dispersed-phase concentration (of oil droplets) in oil-water two-phase flow, which makes it difficult to measure water holdup in oil wells. In this study, we use an ultrasonic method based on a transmission-type sensor in oil-water two-phase flow to measure water holdup in low-velocity and high water-cut conditions. First, we optimize the excitation frequency of the ultrasonic sensor by calculating the sensitivity of the ultrasonic field using the finite element method for multiphysics coupling. Then we calculate the change trend of sound pressure level attenuation ratio with the increase in oil holdup to verify the feasibility of the employed diameter for the ultrasonic sensor. Based on the results, we then investigate the effects of oil-droplet diameter and distribution on the ultrasonic field. To further understand the measurement characteristics of the ultrasonic sensor, we perform a flow loop test on vertical upward oil-water two-phase flow and measure the responses of the optimized ultrasonic sensor. The results show that the ultrasonic sensor yields poor resolution for a dispersed oil slug in water flow (D OS/W flow), but the resolution is favorable for dispersed oil in water flow (D O/W flow) and very fine dispersed oil in water flow (VFD O/W flow). This research demonstrates the potential application of a pulsed-transmission ultrasonic method for measuring the fraction of individual components in oil-water two-phase flow with a low mixture velocity and high water cut.     

Seismic retrofit of reinforced concrete frames using buckling‐restrained braces with bearing block load transfer mechanism

A new method of retrofitting reinforced concrete (RC) frames with buckling‐restrained braces (BRBs) to improve frame strength, stiffness and energy dissipation is proposed. Instead of typical post‐installed anchors, load is transferred between the BRB and RC frame through compression bearing between an installed steel frame connected to the BRB, and high‐strength mortar blocks constructed at the four corners of the RC frame. This avoids complex on‐site anchor installation, and does not limit the allowable brace force by the anchor strength. Cyclic displacements of increasing amplitudes were imposed on two RC frame specimens retrofitted with different BRB strength capacities. In one of the frames, the bearing blocks were reinforced with wire mesh to mitigate cracking. A third RC frame was also tested as a benchmark to evaluate the retrofit strength and stiffness enhancements. Test results indicate that the proposed method efficiently transferred loads between the BRBs and RC frames, increasing the frame lateral strength while achieving good ductility and energy‐dissipating capacity. When the bearing block was reinforced with wire mesh, the maximum frame lateral strength and stiffness were more than 2.2 and 3.5 times the RC frame without the BRB respectively. The BRB imposes additional shear demands through the bearing blocks to both ends of the RC beam and column member discontinuity regions (D‐regions). The softened strut‐and‐tie model satisfactorily estimated the shear capacities of the D‐regions. A simplified calculation and a detailed PISA3D analysis were shown to effectively predict member demands to within 13.8% difference of the measured test results. Copyright © 2016 John Wiley & Sons, Ltd.     

青藏铁路北麓河路段风沙防护体系阻沙效益

在分析青藏铁路北麓河路段风沙灾害现状和风沙环境的基础上,将三维激光扫描技术应用于风沙工程防护体系的效益评价中,利用Leica C10三维激光扫描仪精确测量青藏铁路两侧典型防沙措施及防护体系积沙形态特征和风沙堆积量,评估防护效益。百叶窗条形阻沙栅栏单宽积沙体积最大,为18.31 m³,其次为不通风条形阻沙栅栏,单宽积沙体积为13.66 m³。阻沙栅栏最大防护距离为12 H,即上风向-3~0 H范围和下风向0~9 H范围内,双排结构的阻沙栅栏无论积沙范围或积沙量均较单排结构阻沙栅栏好。在栅栏上风向,沙粒自距栅栏5 m处开始沉降堆积,越靠近栅栏,积沙厚度越大。在阻沙栅栏的下风向,单排结构阻沙栅栏积沙范围为15 m,双排结构阻沙栅栏积沙范围可达20 m。