克拉玛依科博馆倾斜结构抗震设计

结合克拉玛依市科技博物馆工程,对超限倾斜结构设定性能设计目标,并针对性能目标提出抗震措施及抗震构造措施.考虑结构材料的非线性属性,采用静力非线性分析方法,分析倾斜框架-剪力墙结构在地震作用下的响应,尤其是结构在罕遇地震作用下的非线性动力特性.结果表明,结构在罕遇地震下也是安全可靠的,剪力墙尚处在弹性范围,未出现塑性铰,...     

老挝万象平原钾盐矿床控矿构造研究

老挝万象平原钾盐矿层赋存于新近系古新统塔贡组中,主要含钾矿物为光卤石,少量钾石盐.成矿期塔贡组及钾盐矿层主要受北西向的边界断裂及塔贡向斜控制;成矿期后钾盐矿层主要受褶皱(盐向斜、盐背斜)控制.在钾盐矿层沉积后,先在水平应力作用下形成宽缓褶皱.由于向斜部位相对沉降,沉积速度较快,钾盐矿层上部的碎屑岩较厚;而背斜部位相对上...     

海南石碌铁矿床构造变形特征及其与铁多金属成矿富集的关系

海南石碌铁矿曾被誉为“亚洲最大的富铁矿”,其形成、定位与褶皱变形及伴随的剪切、塑性流动等构造密切相关。石碌矿区构造变形大致分为早期(D1)复式向斜的形成时期、晚期(D2)褶皱叠加和剪切变形时期。后者又进一步分为韧-脆性变形(D2a),脆-韧性变形、层间滑脱断层形成(D2b)和脆性变形、矿体破坏(D2c)3个阶段。石碌铁矿床受NW—SE向复式向斜及其与NE—NNE向褶皱叠加所形成的横跨或斜跨褶皱的严格控制;褶皱过程所伴随的剪切变形和高温塑性流动是富铁矿形成的重要机制。复式向斜轴部,尤其是2期向斜褶皱轴的叠加部位往往可发现厚大的富铁矿体。     

Pseudo‐dynamic test of a full‐scale CFT/BRB frame—Part II: Seismic performance of buckling‐restrained braces and connections

This paper is Part II of a two‐part paper describing a full‐scale 3‐story 3‐bay concrete‐filled tube (CFT)/buckling‐restrained braced frame (BRBF) specimen tested using psuedo‐dynamic testing procedures. The first paper described the specimen design, experiment, and simulation, whereas this paper focuses on the experimental responses of BRBs and BRB‐to‐gusset connections. This paper first evaluates the design of the gusset connections and the effects of the added edge stiffeners in improving the seismic performance of gusset connections. Test results suggest that an effective length factor of 2.0 should be considered for the design of the gusset plate without edge stiffeners. Tests also confirm that the cumulative plastic deformation (CPD) capacity of the BRBs adopted in the CFT/BRBF was lower than that found in typical component tests. The tests performed suggest that the reduction in the BRB CPD capacities observed in this full‐scale frame specimen could be due to the significant rotational demands imposed on the BRB‐to‐gusset joints. A simple method of computing such rotational demands from the frame inter‐story drift response demand is proposed. This paper also discusses other key experimental responses of the BRBs, such as effective stiffness, energy dissipation, and ductility demands. Copyright © 2008 John Wiley & Sons, Ltd.     

浆固碎石桩成桩注浆影响范围现场试验研究

浆固碎石桩作为一种新型桩基技术,不仅具有一般刚性桩的桩体置换作用,而且能改善桩周土的力学性质,从而可有效地提高复合地基的承载力及减小沉降变形。通过现场进行成桩前后的桩周土性质研究,验证了注浆对桩周土性质的改善作用,得出成桩时注浆影响范围及分布规律。针对黏性土中浆固碎石桩浆液挤密作用,按平面轴对称问题分析了塑性区边界条件及内部单元体的平衡条件,提出浆固碎石桩浆液影响范围的计算公式。理论公式计算结果与原位测试结果较为符合,从而验证了计算方法的合理性,这对浆固碎石桩的注浆加固具有一定的指导意义。     

FRP约束混凝土矩形短柱的延性分析

将已有混凝土柱延性的定义、纤维截面模型及等效塑性铰方法应用于纤维增强复合材料(FRP)约束矩形混凝土试件的延性分析,通过FRP约束矩形混凝土应力-应变关系考虑FRP约束的影响,计算结果与试验结果符合较好。同时,对FRP约束混凝土矩形柱延性的主要影响参数进行了分析,该方法可以进一步用于FRP约束混凝土试件延性的定量参数研究。     

密肋壁板结构计算模型及Pushover分析

在前期试验和理论研究的基础上,将密肋壁板结构中的密肋复合墙板等效为整体斜撑,提出结构的刚架 - 等效斜撑力学模型,并结合试验数据确立了该模型主要参数的计算方法及塑性铰的设定.采用该模型对一实际密肋壁板结构进行了Pushover分析并进行了抗震性能评估.结果表明采用该模型是实现密肋壁板结构Pushover分析及抗震性能评估的一种有效方法.     

Performance-based concept on seismic evaluation of existing bridges

Conventional seismic evaluation of existing bridges explores the ability of a bridge to survive under significant earthquake excitations. This approach has several major drawbacks, such as only a single structural performance of near collapse is considered, and the simplified approach of adopting strength-based concept to indirectly estimate the nonlinear behavior of a structure lacks accuracy. As a result, performance-based concepts that include a wider variety of structural performance states of a given bridge excited by different levels of earthquake intensity is needed by the engineering community. This paper introduces an improved process for the seismic evaluation of existing bridges. The relationship between the overall structural performance and earthquakes with varying levels of peak ground acceleration (PGA) can successfully be linked. A universal perspective on the seismic evaluation of bridges over their entire life-cycle can be easily obtained to investigate multiple performance objectives. The accuracy of the proposed method, based on pushover analysis, is proven in a case study that compares the results from the proposed procedure with additional nonlinear time history analyses.     

动静力排水固结法在淤泥质地基处理工程中的应用

以广州南沙泰山石化仓储区1期淤泥质地基处理工程为背景,介绍了采用动静力排水固结法处理促淤饱和软黏土地基的基本思想和工艺。该工程施工与现场实时监测相结合,利用孔隙水压力、土体分层沉降和载荷试验等检测指标对加固效果进行了监测和检测。工程实践表明,采取动力即低能量“少击多遍”的强夯施工工艺,辅以填土预压和设置竖向塑料排水板的静力方法来加固淤泥质地基,其效果明显,促淤地基的物理力学性能和抗变形性能显著提高,整体加固效果很好,工后各项指标完全达到或超过预期值。     

煤与瓦斯突出中单个煤壳解体突出的突变理论分析

在煤与瓦斯突出中,煤体自组织地形成最具抗力的球盖壳形式来抵抗被突出,煤壳一旦解体便丧失承载能力,高位势煤岩系统中与单个煤壳突出相应的各种能量得以释放。根据反映煤岩破坏特性的塑性变形局部化理论,导得突出前煤壳形变、位移时相应于偏应力的功、能增量关系,建立了煤壳失稳解体的突变模型,并对由于偏应力作用导致煤壳失稳解体机制进行了研究,给出失稳瞬间释放的偏应力应变能表达式、煤岩系统体积应变能释放量表达式和孔隙瓦斯粉碎解体后的碎煤及与煤层瓦斯渗流形成瓦斯-煤粉两相流描述。所得结果可深化对煤、地应力与瓦斯压力三因素对煤与突出演化规律综合作用的认识。