节理表面波纹度对其闭合性质的影响

节理的表面形貌中普遍含有波纹度。本文分析了含波纹度节理闭合模型的性质，探讨了其接触变形机理，研究了波纹度幅值、频率及不规则度方差对节理闭合性质的效应，最后与将波纹度分量作为随机分量处理的以往的节理闭合模型进行了比较。     

岩体结构面倾向参数概率分布函数改进的Bayes推断方法

三峡船闸是世界上最大的船闸。该地区断层及节理比较发育,且具有一定的随机统计性,它对岩体力学性质起重要的控制作用。为了研究节理倾向的概率分布特征,本文引入以Bayes 最小熵优度比较检验为基础的概率分布的改进Bayes 统计推断方法,基于三峡工程永久船闸节理岩体3373 条结构面的实测参数,就对岩体力学性质起控制作用的各组结构面的倾向参数的概率分布进行了研究。文章最后还讨论了推断的最优分布参数,估计了结构面参数的检验误差范围。     

不连续岩体变形破坏过程中AE的空间演化与意义

通过一些典型节理化岩体模型变形破坏过程中的AE事件的定位分析和破裂面形态的研究,探讨了不连续岩体变形破坏过程的空间演化特征。结果表明：单节理岩体变形破坏的空间动态特征受节理角控制,随着节理角从小变大,岩体的变形破坏方式从AE在局部集中的突发式失稳向AE弥漫于整个节理层面的类似渐进式的破坏形式发展；失稳破裂面从简单的整体状岩-膏界面变成形态复杂的层内复合破裂面；复杂节理岩体的变形破坏受一条（组）主导构造控制,强AE事件集中发生在不连续构造交汇部位,在包含多条主构造的岩体模型中最终失稳破裂面只与最后阶段AE的位置一致。     

节理岩体爆生裂纹扩展动态焦散线模型实验研究

应用动态焦散线测试系统，模拟含节理岩体断裂爆破过程，进行了PMMA模型透射式动态焦散线实验，着重研究了爆炸初始裂纹与节理面夹角不同的情况下，裂纹尖端动态强度因子的变化规律、裂纹穿过节理面的扩展规律、以及炮孔与节理距离不同时裂纹穿过节理扩展的规律。实验结果分析表明，爆生裂纹穿过节理面时，裂纹尖端的动态强度因子和裂纹扩展速度显著下降，穿过节理面后，强度因子又增强；裂纹穿过节理面时，裂纹会沿节理面偏离一段距离后沿原方向继续扩展。实验结果还表明，炮孔与节理间距适宜的情况下，裂纹才会穿过节理继续扩展，间距太小和过大都不利于裂纹的扩展。     

共面闭合断续节理岩体直剪强度特性研究

介绍了节理面和岩桥各自的抗剪强度机制,引入法向变形协调条件,基于Mohr-Coulomb理论,推导了共面闭合断续节理岩体的直剪强度公式。模型试验发现,剪切破坏面以拉剪复合破坏为主,同时岩块中伴随大量的拉张微裂隙。试样的强度和变形具有明显的阶段性,全应力应变曲线主要经历了线弹性增长、节理面错动、次生裂纹起裂稳态扩展、节理面贯通破坏和残余强度5个阶段。对比发现,理论计算结果与试验值吻合较好。     

光弹模拟岩石分形节理的抗剪强度

本文用分形维数人为地制成具有分形曲线的节理面以模拟岩石节理粗糙度特征，利用光弹技术测定了分形节理最大剪应力随维数变化的过程．研究表明，岩石分形节理的抗剪强度不会随分维的增加而无限制地增大     

黄土构造节理研究及其应用

作者发现大量不同力学性质的黄土构造节理后，识别了它们的区域性、系统性特征；认定其两组扭裂面代表新构造应力场最大剪切应力方向，利用黄土构造节理系及由其控制的土层沟槽网络恢复了相应地区Q3-4构造应力场；提出构造节理是黄土区地下水运移的主要通道和赋存的场所；发现构造节理是黄土区地裂缝、滑坡、崩塌和水土流失等地质灾害的构造基础之一，证实构造节理是黄土地层的软弱面，风化和继之而来的应力侵蚀就由此开始，进而逐步塑造黄土碟、穴、井、桥、柱、墙、沟等潜蚀地貌和部分侵蚀地貌。研究黄土构造节理对恢复新构造应力场、帮助预测地裂乃至地震活动、控制水土流失和滑塌灾害、进行工程乃至区域稳定性评价、重新认识黄土潜蚀地貌发育规律、指导干旱半干旱黄土区找水，既有理论意义又有实际意义。     

岩石分形节理粗糙性对应力场影响的光弹模拟研究

节理的粗糙性是影响岩体力学特性的重要因素。现有的众多的研究结果表明：不规则的节理面具有很好的自相似特征，可以用分形几何去描述，节理面的分形维数是表征节理面粗糙度（ＪＲＣ）恰当的统计量。基于以上观点，为了能够精确地控制节理面的粗糙性，本文以Ｍａｎｄｅｌｂｒｏｔｗｅｉｅｒｓｔｒａｓｓ函数生成不同分维的分形曲线来模拟实际的粗糙节理面，制成光弹实验试样进行多组的单压和压剪实验，通过光弹条纹和接触点的变化来研究不规则的节理对于岩体变形，应力场的影响，得出了一些有益的结论．     

含节理岩体爆生裂纹扩展的动焦散模型实验研究

应用动态焦散线测试系统,模拟含节理岩体断裂爆破过程,进行了PMMA模型透射式动态焦散线实验,着重研究了爆炸初始裂纹与节理面不同夹角的情况下,裂纹尖端动态应力强度因子的变化规律,裂纹穿过节理面的扩展规律,以及裂纹扩展速度的变化规律。实验结果分析表明,爆生裂纹穿过节理面时,裂纹尖端的动态应力强度因子和裂纹扩展速度显著下降,穿过节理面后,应力强度因子又有所增强;裂纹穿过节理面时,裂纹会沿节理面偏离一段距离后沿初始裂纹方向继续扩展。研究结果可以为节理岩体的断裂爆破提供理论依据。     

考虑损伤的节理本构模型

本文在弹塑性损伤的理论框架内，讨论了节理等地质间断面的本构模型。这个模型能够反映节理面的损伤弱化，扩容和弹性刚度劣化等复杂特性。这个模型的另一优点是，塑性变形增量与屈服面是非正交的，但本构矩阵具有对称性。这种对称性在岩石力学的理论研究和数值分析中是至关紧要的。     

Thermo-mechanical modelling of the contact between rough surfaces using homogenisation technique

In this study, thermo-mechanical behaviour of contacting rough surfaces has been modelled. Firstly, a numerical microscopic contact model that considers the properties of engineering surfaces has been developed. Geometrical characteristics of rough surfaces are deduced using the standard procedure for roughness and waviness parameter determination according to the so-called “motif” procedure. Secondly, an equivalent macroscopic contact model using a homogenisation technique has been presented. The interfacial behaviour of this model has been governed by the curves deduced from the microscopic model. The transition from microscopic to macroscopic scale was also validated.     

机床结构结合面静态特性研究与内聚力模拟

针对机床结构中的平面结合面,通过实验分析了结合面在均布面压作用下的结合面法向变形与平均压力的关系;将结合面表面简化为半圆弧和正弦曲线两种微观形貌,利用有限元方法模拟结合面的接触变形力学行为,计算结果显示半圆弧形貌接触分析结果与实验结果较为接近.从结合面作用的物理本质出发,将结合面的相互作用等效为内聚力效应,利用内聚力模型分析了结合面的静态力学行为;内聚力模型计算结果与实验结果吻合较好.     

Compressive strength of fibre composites with random fibre waviness

The compressive strength of unidirectional long fibre composites is predicted for plastic microbuckling from a random two-dimensional distribution of fibre waviness. The effect of the physical size of waviness is addressed by using couple stress theory, with the fibre bending resistance scaling with the fibre diameter d. The predicted statistical distribution of compressive strength is found using a Monte Carlo method. An ensemble of fibre waviness profiles is generated from an assumed spectral density of waviness and the compressive strength for each such realisation is calculated directly by the finite element method. The average predicted strength agrees reasonably with practical values, confirming the hypothesis that microbuckles can be initiated by fibre misalignment. It is found that the probability distribution of strength is well matched by a Weibull fit, and the dependence of the Weibull parameters upon the spectral density of waviness is determined. For the practical range of fibre distributions considered, it is concluded that the strength depends mainly upon the root mean square amplitude of fibre misalignment, with the shape of the power spectral density function playing only a minor role. An engineering model for predicting the compressive strength is proposed, akin to weakest link theory for materials containing flaws. A specimen containing randomly distributed waviness is examined to locate regions of high-fibre misalignment. The strength of each of these weak regions is estimated from a look-up table derived from calculations with idealised circular or elliptical patches of waviness. The strength of the composite is given by the failure stress associated with the weakest such patch. For random distributions of waviness, the predictions using this engineering approach are in good agreement with the direct calculations of strength using the finite element method.     

Mechanical homogenisation of masonry wall without mortar

Some refractory linings of metallurgical vessels consist of masonry without mortar. To describe the mechanical behaviour of these large-sized structures, it is necessary to use an equivalent material instead of a model that comprises all the bricks and joints involved. The properties of the equivalent material depend on the opening and closure mechanism of joints. In this paper, four joint states which are the combination of open/closed states of bed and head joints are identified, and the corresponding equivalent elastic properties are determined accordingly using homogenisation techniques. The transition criterion between these joint states is based on the unilateral contact conditions written in terms of macroscopic strain. The developed model is then compared to an in-plane biaxial compression test. The numerical and experimental results are in good agreement.     

磨料水射流冲蚀金属损伤形貌特征及机理研究

针对前混合磨料水射流冲蚀过程,进行了冲蚀试验及仿真研究.从试验中得到了材料冲蚀损伤形貌特征.采用SPH耦合FEM方法建立相应的冲蚀模型,对材料冲蚀过程进行模拟分析,揭示了材料损伤形貌特征产生的机理.结果表明:随着冲蚀深度的增加,磨料颗粒的冲蚀动能逐渐减小,冲蚀角度逐渐增大,材料冲蚀损伤由微切削和微犁削逐渐变为冲击变形,材料冲蚀损伤断面的形貌特征逐渐恶化,具体表现为拖尾角和表面粗糙度逐渐增大.不同金属材料损伤断面形貌特征具有相似性,但是金属材料属性的差异会对磨料冲蚀过程产生影响,导致条纹在材料损伤断面上的分布和条纹角度出现差异.由于材料损伤形貌特征受控于磨料颗粒运动特性,因此材料冲蚀断面质量改善应该从改变磨料颗粒运动特性角度出发,这为进一步研究材料冲蚀断面质量改进奠定了理论基础.     

Prediction of stress–strain and fracture behaviour of an 8-Harness satin weave ceramic matrix composite

A computationally economic finite-element-based approach has been developed to predict the stress–strain and fracture behaviour of an 8-Harness satin woven ceramic matrix composite with strain-induced damage. The finite element analysis utilises a solid element to model the behaviour of the homogenised orthotropic uni-directional tow and its matrix. The underpinning models of the tow and matrix, (Tang et al., 2009) capture the physics of the interactions between fibres and matrix; and, in this way, permit modelling that bridges the length scales of the fibres and full-scale components. The non-linear multi-axial stress–strain behaviour of the composite has been discretised by multi-linear elastic curves; and the latter has been used as input to a user defined subroutine, UMAT, in the commercial finite element package, ABAQUS. A partial unit cell model has been constructed of the 8-Harness satin weave composite of carbon fibres embedded in an amorphous carbon matrix, HITCO C/C. Predictions of the global stress–strain curve, which include the effects of fibre waviness, have been made for two failure modes: the first by deformation localisation, and the second by dynamic tow failure on fibre fracture, triggered by instantaneous pull-out deactivation. Comparisons have been made between the predictions and experimental data that exhibit two classes of fracture behaviour: brittle and quasi-ductile. The predicted results, both with and without tow waviness, compare well with the experimental data; however, the predictions for waviness are slightly better. The two extremes of experimental behaviour have been found to correspond with the two tow fracture criteria modelled.     

缝合复合材料层板面内局部纤维弯曲模型及刚度预报

提出了缝合层板面内局部纤维弯曲模型,假设缝合线受挤压后横截面为椭圆形,指出当纤维弯曲幅度较小时,缝合仅造成单胞内局部纤维弯曲,纤维弯曲角为特定值,由纤维种类决定;当纤维弯曲幅度较大时,缝合造成单胞内整体纤维弯曲,纤维弯曲角大于特定值,由纤维弯曲幅度和单胞尺寸决定。采用有限元法建立了缝合层板刚度分析方法,使缝合层板单胞满足周期性边界条件,预报结果与试验吻合较好,详细探讨了缝合参数对层板刚度的影响规律,结果表明缝合后层板刚度降低,缝合参数变化对层板刚度有较大影响。