基于能量法测量节理岩体品质因子的实验研究

品质因子是衡量岩体中应力波衰减特性的一个重要参数。利用分离式霍普金森压杆实验系统对含人工节理花岗岩试样进行单轴冲击压缩实验,研究节理吻合系数(JMC)对岩体试样品质因子的影响。首先,根据品质因子基本概念得出了利用应力波能量计算品质因子的方法,并证明在试样严格满足应力均匀条件时,其与应力–应变曲线方法是等价的。然后,用三波法得到了节理试样的应力–应变曲线,同时用应力波能量方法计算了品质因子。实验结果表明:随着节理吻合系数(JMC)降低,应力–应变曲线滞回环面积增加,节理岩体试样的动态割线模量和品质因子均减小,说明节理接触面积减小弱化了整个试样并且使试样能量耗散能力增加。     

Laboratory-scale investigation of response characteristics of liquid-filled rock joints with different joint inclinations under dynamic loading

In underground rock engineering, water-bearing faults may be subjected to dynamic loading, resulting in the coupling of hydraulic and dynamic hazards. Understanding the interaction mechanism between the stress waves induced by dynamic loadings and liquid-filled rock joints is therefore crucial. In this study, an auxiliary device for simulating the liquid-filled layer was developed to analyze the dynamic response characteristics of liquid-filled rock joints in laboratory. Granite and polymethyl methacrylate (PMMA) specimens were chosen for testing, and high-amplitude shock waves induced by a split Hopkinson pressure bar (SHPB) were used to produce dynamic loadings. Impact loading tests were conducted on liquid-filled rock joints with different joint inclinations. The energy propagation coefficient and peak liquid pressure were proposed to investigate the energy propagation and attenuation of waves propagating across the joints, as well as the dynamic response characteristics of the liquid in the liquid-filled rock joints. For the inclination angle range considered herein, the experimental results showed that the energy propagation coefficient gently diminished with increasing joint inclination, and smaller coefficient values were obtained for granite specimens compared with PMMA specimens. The peak liquid pressure exhibited a gradually decreasing trend with increasing joint inclination, and the peak pressure for granite specimens was slightly higher than that for PMMA specimens. Overall, this paper may provide a considerably better method for studying liquid-filled rock joints at the laboratory scale, and serves as a guide for interpreting the underlying mechanisms for interactions between stress waves and liquid-filled rock joints.     

复杂介质对地震波传播的影响

本文基于两相介质动力学方程组,利用显式集中质量有限元结合透射人工边界,研究了水平自由场地单相土、欠饱和土和饱和土及不同模量的土层排列结构对地震波传播的影响。结果表明介质的性质对P 波传播有明显的影响;而土层结构对SV 波传播有明显影响。同时,本文还研究了横向不均匀场地地震反应,结果进一步表明,仅用一维模型研究横向不均匀场地会引起较大误差。     

Experimental research on seismic behavior of reinforcedconcrete shear wall with construction joint

施工缝的存在会在一定程度上影响剪力墙的性能,为研究施工缝对钢筋混凝土剪力墙抗震性能的影响,对整浇和带施工缝两种剪力墙试件进行拟静力试验。通过对比分析施工缝对剪力墙破坏过程的影响,并从滞回曲线、承载能力、变形能力、耗能、刚度退化和破坏过程等方面分析施工缝对剪力墙抗震性能的影响。研究结果表明,同等条件下带缝剪力墙与整浇剪力墙的最后破坏形态基本一致,但是裂缝发展过程明显不同,带缝试件初始裂缝及贯通裂缝出现在施工缝处,而整浇试件的初始裂缝及贯通裂缝出现位置比较随机。轴压比较小时,整浇试件的承载力和耗能比带缝试件高;轴压比较大时,轴向力抵消了施工缝的不利影响,带缝试件的承载力和耗能比整浇试件的高;整浇试件的延性和刚度退化均比带缝试件的小;配筋率提高使带缝试件的承载力提高、耗能增大,但对刚度的影响较小;轴压比增大使带缝试件的延性降低、刚度退化变快。     

含软弱夹层岩质边坡在爆破地震波下的试验研究

为探求地质工程中爆破地震波作用下含软弱夹层边坡的动力响应特性,设计由混凝土基座和边坡模型组成的物理模拟试验,采用雷管和乳化炸药施加爆破地震波,开展考虑爆破孔位置和炸药量影响的多次爆破试验.首先,对速度、加速度响应分别进行快速傅里叶变换(FFT)、希尔伯特—黄变换(HHT),两者的频谱结果均表明符合爆破地震波的特征;然后...     

装配式新型梁-柱钢连接节点抗震性能研究

与传统建筑业相比,装配式建筑具有能耗低、施工周期短、施工现场环境好等优点.本文基于现有的装配式RC结构梁-柱节点连接方式,提出了一种用于装配式RC结构的新型梁-柱钢连接节点,以期克服现浇混凝土连接节点施工效率低的缺点,同时保证节点的强度和稳定性,进而确保结构具有良好的整体性.通过有限元分析软件ABAQUS对现浇与新型梁...     

Stochastic wave models for stationary and homogeneous seismic ground motion

A fundamental theory of stationary, homogeneous stochastic waves is developed and a technique for digitally generating samples of such waves is introduced as a further extension of the spectral representation method. This is done primarily for the purpose of developing an analytical model for propagating seismic waves that can account for their stochastic characteristics in the time and space domain. From this model, the corresponding sample seismic waves can be digitally generated with great computational efficiency. The efficacy of this technique is demonstrated with the aid of a numerical example in which a sample of a stationary, homogeneous, two-dimensional, dispersive Rayleigh wave consistent, in its analytical form of spatial variability, with Lotung, Taiwan dense-array data is digitally generated. Although the stochastic wave model considered in this work is stationary and homogeneous, it is a straightforward task to extend the methodology introduced to nonstationary and / or non-homogeneous stochastic waves characterized by an evolutionary power spectrum.     

施工缝对框架柱抗震性能影响的试验研究

为研究施工缝对钢筋混凝土框架柱抗震性能的影响,对整浇柱和在底部设施工缝的带缝柱两种类型构件进行拟静力试验。通过对比深入分析施工缝对柱端传力机制和破坏机理的影响,并且从耗能、纵筋滑移、应力分布及剪切变形分量所占比重等不同角度分析施工缝对柱子抗震性能的影响。结果表明,同等条件下带缝柱与整浇柱的破坏形态一致,但是裂缝发展过程和破坏机理明显不同;施工缝使破坏区域集中,塑性铰长度减小;施工缝对柱抗震性能的影响程度主要与轴压比和剪跨比有关;混凝土接缝面之间的摩擦力和抗剪能力均与轴向荷载的大小有关;施工缝有割裂力在上下混凝土间的传递和利用缝面摩擦力增大耗能能力两种效应,具体哪种效应起控制作用取决于施工缝面法向应力和切向剪力的相对大小。     

SV波斜入射对岩体隧道洞身段地震响应影响研究

基于显式有限元方法并结合黏弹性人工边界条件,推导了SV波斜入射时人工边界面上等效节点力的计算公式,并基于通用有限元软件实现了SV波的倾斜输入。采用简单算例验证了SV波斜入射输入方法的准确性。分别考虑了SV波在隧道横断面和纵断面内斜入射工况,研究了SV波斜入射条件下岩体隧道洞身段地震响应规律。计算结果表明：SV波斜入射时的隧道地震响应规律与垂直入射时具有较大的差异;SV波在不同断面内斜入射时隧道的地震响应结果也具有较大差别。     

爆破地震波作用下隧道围岩动应力集中系数分析

将爆破地震波进行合理近似简化,采用波函数展开法,推导了无限岩石介质中爆破地震波作用下隧道围岩动应力集中系数的表达式,结合具体算例,从理论上定量分析了围岩不同位置上爆破地震波主频和围岩物理力学指标对动应力集中系数的影响。分析结果表明：隧道围岩迎爆侧的动应力集中系数整体上大于背爆侧,动应力集中系数峰值偏向于迎爆侧;在不同主频爆破地震波作用下,动应力集中系数的影响存在最大值;隧道围岩的弹性模量对动应力集中系数的影响较大,而泊松比对动应力集中系数的影响较小。     

高速铁路隧道围岩参数空间变异性的力学响应分析

 针对大断面高速铁路隧道围岩的参数变异性及空间相关性等问题,在随机场理论的基本框架下,将非侵入式随机分析、地层结构模型、有限差分法和蒙特卡洛模拟有机结合,提出考虑围岩参数空间变异性的非侵入式随机有限差分分析模型。运用该模型对隧道开挖后围岩的力学响应进行分析,得到围岩参数空间变异性的2个基本要素：参数变异性和空间相关性,其特征参数的取值变化会直接影响到围岩变形特性、塑性区发展模式以及地表沉降形态。同时与确定性模型的计算结果进行比较,提炼出隧道开挖后围岩参数空间变异性的4种典型工程效应：(1) 围岩结构性低强度荷载占优效应;(2) 围岩结构空间相关各向异性效应;(3) 功能函数敏感性差异及非线性效应;(4) 功能函数转变分布类型效应。研究成果为拓展基于空间变异性的高速铁路隧道工程稳健性设计奠定了一定的基础。     

装配式梁柱外环板高强螺栓连接节点#br# 抗震性能试验研究

针对装配式梁柱外环板高强螺栓连接节点抗震性能开展了拟静力加载试验,研究节点试件的破坏模式、滞回曲线、骨架曲线、延性、耗能、刚度退化等抗震性能指标;并对影响节点试件抗震性能参数进行分析;研究节点试件层间位移角及转动能力;提出节点恢复力计算模型。研究结果表明：节点试件失效模式为外环板与梁翼缘连接螺栓剪断、梁翼缘钢板断裂、外环板与柱连接处焊缝开裂3种形式;4个节点试件的滞回环面积较为饱满并呈“Z”形,具有较强的耗能能力;4个节点试件均有显著的刚度退化现象,下降坡度平缓;4个节点试件的层间位移角为0.09～0.12rad超过抗震规范的要求,表明节点具有良好的转动能力和延性性能;外环板的厚度和宽度对节点抗震性能有一定影响;提出的节点恢复力计算模型与节点试件的试验曲线吻合较好。     

岩体中弹性波传播尺度效应的初步分析

含缺陷岩体具有尺度效应,此类岩体中传播的弹性波也有尺度效应。对现场测点 EC37-201-06 ,在 3.0 ´ 3.2 m² 的范围内采用动态有限元方法进行了 15 种尺度的弹性波传播规律的分析研究。对现场测点 EC37-101-06 ,在 1.2 ´ 1.2 m² 的范围内采用准静态有限元方法进行了 60 种尺度的弹性波波速与围压及计算尺度的关系的计算分析。前者采用了射线理论分析思想,而后者采用等效介质分析思想,得到了相应的弹性波的尺度效应,但二者规律有差异。为建立二者间的联系,也为了工程应用,基于量纲理论分析方法,给出了一个半理论的波速与入射波频率的计算公式。与现场声波和地震波测试结果,以及考虑随机分布单节理散射模型的计算结果进行比较,初步分析结果表明,此公式基本可行。     

自复位装配式钢-混凝土混合框架节点抗震性能试验研究

结合装配式梁、柱构件螺栓连接施工便捷的特性与后张预应力筋预压连接的抗震性能优势,提出一种自复位装配式钢-混凝土混合结构框架节点,该节点由钢筋混凝土柱和钢-混凝土混合梁通过高强螺栓拼装而成,主要通过后张梁内的无黏结预应力筋提供复位力,并通过摩擦耗能装置与钢梁段塑性变形进行耗能。共完成了5个边节点的低周往复加载试验,分别研究了混合梁内预应力筋的初始预拉力与摩擦装置中高强螺栓的初始预紧力对该节点承载能力、抗震性能、耗能能力和复位能力的影响。研究结果表明：试件表现出明显的两阶段滞回特性,第一阶段为钢梁段屈服前,混凝土梁与钢梁段接触面呈现出持续开合复位机制,滞回曲线呈现明显双旗形,复位效果明显;第二阶段为钢梁段屈服后,随着荷载增大,钢梁的塑性变形逐渐增大,滞回曲线趋于饱满,试件耗能能力显著增加。试件的峰值荷载、延性系数和累积耗能值随摩擦装置中高强螺栓的初始扭矩增大而增大,峰值荷载和复位能力随梁内预应力筋的初始预拉力增大而增大。在整个试验过程中,各试件梁、柱主体构件损伤不明显,基本实现震后可恢复。     

Stability analysis of rock blocks around a tunnel using a statistical joint modeling technique

A three-dimensional statistical joint modeling technique was used to analyze the stability of rock blocks around a tunnel. The rock blocks generated from the joints and the tunnel were analyzed for their volume, height, perimeter, safety factor, and probability of occurrence. All these procedures were programmed into the computer program blocstab. The characteristics of rock block occurrence due to the variation of joint persistence (diameter), orientation and volumetric frequency were investigated. The rock block stability around a storage cavern of liquefied petroleum gas in Korea was analyzed as a case study. Here, the joints were assumed to follow the Baecher disk model for their shape and location, and their orientations were modeled by the Fisher distribution. The joint diameter distribution was estimated by using the window sampling method recently developed by Song and Lee.     

不同地应力下爆炸应力波在节理岩体中传播规律模型试验研究

 通过模型试验研究不同地应力下应力波在节理岩体中的传播规律,同时考虑节理数量的影响,并推导地应力作用下应力波在多条非线性节理处的传播方程。首先,通过导爆索产生爆炸应力波,监测不同位置的应力,研究地应力下节理岩体中应力波传播的衰减组成,并分析地应力以及节理数量对应力波衰减的影响,其次,考虑地应力对非线性节理模型的影响,结合时间递归分析法,得出地应力作用下应力波在多条非线性节理处的传播方程,并将计算结果与试验数据进行对比分析。研究结果表明,高地应力下,爆炸应力波在节理岩体中传播时,其衰减主要由岩石材料和节理两部分分别引起的衰减叠加组成,随着地应力增加,节理岩体对应力波的衰减增强,其中岩石材料对应力波的衰减作用加强,而节理引起的衰减减弱。     

关于水平地震作用下框架节点柱端设计的建议

归纳了框架结构的几种破坏形式,讨论了钢筋混凝土框架节点柱端的一些影响因素,并针对性的提出了几点建议,以期为钢筋混凝土框架节点设计和研究积累经验。     

硬岩深孔爆破破坏范围地震波CT测试

硬岩巷道掘进工作效率受岩石硬度影响较大,采用深孔爆破可以对岩层产生不同程度的弱化作用。为了有效评价爆破弱化范围及特征,采用地震波CT测试技术,在不同开挖断面布置CT测试观测系统进行数据采集,利用SIRT反演方法获得断面波速分布结果,进一步划分爆破波速异常范围作为岩石弱化范围。实际应用结果表明,本次测试爆破孔弱化范围在0.4～1.2m,且影响程度沿钻孔自外向内有减小的趋势。该方法测试效果显著,可为爆破技术改进提供有效的技术参数。     

钢管混凝土叠合柱-钢筋混凝土梁外加强环节点抗震性能试验研究

针对实际工程设计中的钢管混凝土叠合柱-钢筋混凝土梁外加强环节点,对其进行抗震性能试验研究。以3个不同外加强环形式的平面中节点的低周反复荷载试验为基础,结合有限元分析,对节点的承载力、刚度、延性、耗能能力、变形性能以及外加强环的应变分布规律进行分析。研究结果表明：不同外加强环形式的试件在梁端往复荷载作用下的破坏过程和破坏模式基本一致,试件的整体滞回性能和承载力、刚度退化规律也很相近,外加强环应变分布规律基本相同,均具有良好的承载力、延性及耗能能力。基于研究结果,对采用外加强环的钢管混凝土叠合柱-钢筋混凝土梁节点的构造措施提出了建议。     

Finite element analysis on the seismic behavior of side joint of Prefabricated Cage System in prefabricated concrete frame

The Prefabricated Cage System (PCS) has the advantages of high bearing capacity and good ductility. Meanwhile, it is convenient for factory production and it is beneficial to the cost savings, construction period shortening. Side joint is the weak region of PCS concrete frame and has great influence on seismic behavior of the whole structure. Thus systematically study on the seismic behavior of PCS concrete side joint is necessary. This paper presents a finite element study on behavior of the side joint under seismic loading. In the finite element model, PCS concrete and the reinforced concrete (RC) is modeled by the solid element and fiber-beam element, respectively. The numerical results is compared with the experimental results and it is found that the results of model based on fiber-beam element is in better agreement with the experimental results than solid element model. In addition, the overall seismic behavior of the side joints in PCS concrete is better than that of the RC with the same strength.