昌邑市镇村违法用地群防网建设的探索与实践

昌邑市多措并举,强化镇村监管责任,推进执法重心下移,探索建立了违法用地＂群防群治＂立体体系,始终保持对违法违规用地严厉打击的高压态势,建立了土地利用管理新秩序,维护了全市和谐稳定发展大局。     

土石混填料台背回填柔性加筋注浆技术加固试验研究

通过采用柔性加筋注浆技术处理台后回填土现场试验研究并结合室内试验的方式,研究了柔性加筋注浆新技术处理湘西红砂岩土石混填台背的施工工艺特性、加固实现机制和加固效果。现场试验及质量测试表明,水平柔性加筋注浆新技术处理湘西红砂岩土石混填台背施工工艺简单、加固效果良好,具有较好的开发应用价值。同时,现场试验过程取得大量施工参数和试验数据,为改进该新技术的设计计算及施工参数、完善施工工艺获得素材; 对有效预防和减少桥头跳车现象的发生,保证行车的舒适和安全也提供了可供选择的新方式。     

Quasi-plane-hypothesis of strain coordination for RC beams seismically strengthened with externally-bonded or near-surface mounted fiber reinforced plastic

The application of fiber reinforced plastic(FRP),including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement(EBR) and near-surface mounted(NSM) strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height(h 0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation:ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.     

Strengthening of moment‐resisting frame structures against near‐fault ground motion effects

Near‐fault ground motions with forward directivity are characterized by a large pulse. This pulse‐like motion may cause a highly non‐uniform distribution of story ductility demands for code‐compliant frame structures, with maximum demands that may considerably exceed the level of code expectations. Strengthening techniques for multi‐story frame structures are explored with the objective of reducing maximum drift demands. One option is to modify the code‐based SRSS distribution of story shear strength over the height by strengthening of the lower stories of the frame. The modified distribution reduces the maximum story ductility demand, particularly for weak and flexible structures. However, this strengthening technique is less effective for stiff structures, and is almost ineffective in cases in which the maximum demand occurs in the upper stories, i.e. strong and flexible structures. As an alternative, the benefits of strengthening frames with elastic and inelastic walls are evaluated. The effects of adding walls that are either fixed or hinged at the base are investigated. It is demonstrated that strengthening with hinged walls is very effective in reducing drift demands for structures with a wide range of periods and at various performance levels. Wall inelastic behavior only slightly reduces the benefits of strengthening with hinged walls.Copyright © 2004 John Wiley & Sons, Ltd.     

地下排水与观测廊道加固方案的现场试验论证

华东天荒坪抽水蓄能电站上水库库底的地下排水与观测廊道为城门洞型,拱体为预制混凝土,边墙与底板现浇。运行期间发现廊道拱顶沿纵向开裂。电厂曾采用外加钢结构支撑混凝土拱顶的方案进行了加固处理,但裂缝开裂并没有得到有效控制。为弄清拱顶开裂原因,提出有效的改造加固方案,为此,进行了现场试验,结果表明:预制混凝土拱脚相对现浇边墙发生向外侧的滑动,是导致开裂的主要原因,因此,阻止其相对滑动,是加固处理的关键。     

Determination of mechanical properties of traditional masonry walls in dwellings of Faial Island,Azores

The determination of mechanical properties of masonry walls is a fundamental pre‐requisite for the characterization of the seismic response of traditional buildings, which helps on the definition of adequate rehabilitation and strengthening procedures. This paper presents a testing campaign carried out in the Cedros region of Faial Island, Azores, hit by the July 98 earthquake, aiming at the determination of physical and mechanical properties of stone masonry walls, namely the mass density and Young's modulus. The paper describes the developed testing techniques as a contribution to the study and the preservation of traditional masonry buildings. Copyright © 2002 John Wiley & Sons, Ltd.     

某砖砌体教学楼结构抗震加固设计

某中小学教学楼为典型的80年代建造的砌体教学楼,鉴定结果显示基础稳定,上部结构材料强度不足,部分构造设置不合理。在结构抗震加固再设计中,从概念上分析结构加固的合理性;合理地确定地震作用影响系数,对加固前后的结构进行整体计算分析;对重要及复杂的部分节点进行补充设计。     

The effect of dissolved magnesium on creep of calcite II: transition from diffusion creep to dislocation creep

We extended a previous study on the influence of Mg solute impurity on diffusion creep in calcite to include deformation under a broader range of stress conditions and over a wider range of Mg contents. Synthetic marbles were produced by hot isostatic pressing (HIP) mixtures of calcite and dolomite powders for different intervals (2–30 h) at 850°C and 300 MPa confining pressure. The HIP treatment resulted in high-magnesian calcite aggregates with Mg content ranging from 0.5 to 17 mol%. Both back-scattered electron images and chemical analysis suggested that the dolomite phase was completely dissolved, and that Mg distribution was homogeneous throughout the samples at the scale of about two micrometers. The grain size after HIP varied from 8 to 31 μm, increased with time at temperature, and decreased with increasing Mg content (>3.0 mol%). Grain size and time were consistent with a normal grain growth equation, with exponents from 2.4 to 4.7, for samples containing 0.5–17.0 mol% Mg, respectively. We deformed samples after HIP at the same confining pressure with differential stresses between 20 and 200 MPa using either constant strain rate or stepping intervals of loading at constant stresses in a Paterson gas-medium deformation apparatus. The deformation tests took place at between 700 and 800°C and at strain rates between 10⁻⁶ and 10⁻³ s⁻¹. After deformation to strains of about 25%, a bimodal distribution of large protoblasts and small recrystallized neoblasts coexisted in some samples loaded at higher stresses. The deformation data indicated a transition in mechanism from diffusion creep to dislocation creep. At stresses below 40 MPa, the strength was directly proportional to grain size and decreased with increasing Mg content due to the reductions in grain size. At about 40 MPa, the sensitivity of log strain rate to log stress, (n), became greater than 1 and eventually exceeded 3 for stresses above 80 MPa. At a given strain rate and temperature, the stress at which that transition occurred was larger for samples with higher Mg content and smaller grain size. At given strain rates, constant temperature, and fixed grain size, the strength of calcite in the dislocation creep regime increased with solute content, while the strength in the diffusion creep regime was independent of Mg content. The results suggest that chemical composition will be an important element to consider when solid substitution can occur during natural deformation.     

Twin lintel belt in steel for seismic strengthening of brick masonry buildings

A single-room, single-storey full-scale brick masonry building with precast RC roofing system was tested thric eunder displacement controlled lateral cyclic loading, to assess the effectiveness of the basic repair and seismic strengthening techniques. Initially, the virgin building specimen was loaded laterally to failure, In the second stage, the damaged building was repaired by stitching across the cracks, and tested under the same lateral loading. In the third stage, the twice-damaged structure was repaired once more by stitching and strengthened by twin lintel belt in steel and vertical corner reinforcement,and re-tested. The building strengthened by twin lintel belt in steel showed about 28% higher strength under lateral loading than the virgin building.     

黏度时变性灌浆材料加固碎裂岩体应用研究

针对普通水泥浆流动时间长、早期强度低、可灌性差,在复杂岩体注浆中质量难以保证的问题,提出以普通水泥浆为基浆,对普通水泥浆适当掺加外掺剂进行改良,以调节水泥水化及硬化进程,形成SJP黏度时变性灌浆材料。其特征主要为浆液初始流动性好,浆液黏度增长缓慢,浆液过可泵时间后其黏度将迅速增大,浆液在可泵时间内保持良好的可灌性;浆液流动时间可控,可泵时间到初凝时间间隔短,浆液不易被冲蚀;同时浆液固结体具有前期强度增长快,后期强度高的特点;可以根据不同岩层特点,改变外掺剂的加入量,可以形成与地层良好适应性的灌浆材料。应用结果表明:对于陡倾、宽缝、碎裂岩体,SJP黏度时变性灌浆材料具有良好适宜性,可以作为锚杆灌浆材料,在减少材料用量的同时,可缩短工时,灌注质量满足设计要求。SJP灌浆材料已应用到坝基加固、房屋地基处理、地质灾害治理工程中。