Study on Failure Mechanism and Macro-meso Damage Constitutive Model of Concrete-like Materials

混凝土、岩石材料是由颗粒组成的一类脆性材料，都先天带有微裂隙（裂纹）等缺陷以及不均质性等特点，因此它们具有相近的力学性质。混凝土类材料破坏机理及本构模型的研究一直是土木工程学科最为重要的问题之一，最近发展起来的损伤力学理论为该研究提供了一种新的研究思路和方法。利用连续损伤理论分析混凝土类材料破坏的损伤机理，并结合统计强度理论建立混凝土类材料受压破坏全过程的损伤本构模型成为研究热点。本文以混凝土和岩石材料为研究对象，从室内试验出发，利用连续损伤理论分析混凝土类材料破坏的损伤机理，并结合统计强度理论建立混凝土类材料受压破坏全过程的损伤本构模型。在建立损伤本构模型的过程中，通过混凝土类材料破坏过程的...Concrete and rock materials, a class of brittle materials composed of grain, which are both inherent with defects (such as micro-cracks) and non-homogeneous characteristics have similar mechanical properties.The research for failure mechanism and constitutive model of concrete-like materials has been one of the most important issues of Civil Engineering all along and a recently developed damage me...学位：工学硕士院系专业：建筑与土木工程学院土木工程系_工程力学学号：2532007115220

改良非创伤性修复技术对部队龋病患者的防治效果评价

目的:探讨适宜于部队官兵龋病防治可行性和实用性的方式。方法:应用非创伤性标准器械和Carisolv工具及凝胶以非创结合微创的方法对某部官兵206牙,进行去腐充填,并对修复体完好率进行1年的随访。结果:3、6、12个月后成功率分别为97.6%、95.2%、92.1%。结论:改良非创伤性修复技术适合于基层部队龋病防治,效果良好

混凝土受压过程中声发射数的灰色模型研究

针对在混凝土单轴受压破坏全过程的声发射试验中,采用传统GM(1,1)灰色模型多步预测分析所得预测值普遍较实测值偏大、预测精度偏低的问题,通过引进预测值折减系数,重点探讨了折减系数的特点。结果表明,折减系数在预测曲线起点处基本为一常数,在终点处基本与已知数据百分数呈线性关系。基于上述特点通过插值求其折减系数来合理修正传统的灰色模型,建立起折减修正GM(1,1)灰色模型。通过该修正GM(1,1)灰色模型对室内声发射试验建立的预测模型,其精度较传统GM(1,1)灰色模型有较大提高

基于不同初值的微震源定位方法

分析微震源定位方法中的线性定位方法和Geiger定位方法以及各自特点,并提出线性定位方法和Geiger定位方法相结合的联合定位方法。以柿竹园全数字多通道微震监测系统为背景,通过进行人工定点爆破试验,分别采用线性定位方法、常规Geiger定位方法及联合定位方法对震源进行定位。通过与实际爆破坐标进行对比分析得出,联合定位方法解决线性定位求解精度低的问题;同时优化常规Geiger定位方法初值选择,提高迭代求解效率,避免当Geiger定位方法求解出现奇异矩阵时,迭代初值不准确造成定位误差较大甚至无法定位等问题

深埋双轨巷道围岩与支护结构稳定性的有限元仿真分析

采用有限元方法对深埋双轨巷道在无支护和有支护条件下围岩与支护结构的受力及变形特征进行分析,给出两种支护条件下围岩的应力分布特征、巷道周边特征点的变形(位移)大小及破坏区的范围,对支护前后巷道周边特征点处的应力、位移和屈服度进行对比分析,计算了混凝土支护结构所受内力和弯矩的大小,并给出其分布特征图。通过研究得出围岩能够自行稳定、支护结构设计参数合理和原设计方案可行的结论

类岩石材料声发射参数与应力和应变耦合本构关系

利用液压伺服试验系统和声波监测仪开展了岩石和混凝土材料声发射特性试验研究,并在试验基础上研究了损伤变量与声发射参数之间的量化关系.结果表明,损伤变量与声发射参数呈线性关系.采用基于Weibull分布的损伤本构模型及损伤变量与声发射数间的经验公式,推导出应力、应变参量与声发射数参量的耦合模型,该模型参数可以根据应力--应变全曲线及损伤变量与声发射数关系曲线的几何边界条件确定其表达式,方式简单适用.通过与岩石和混凝土试样单轴压缩试验实测结果对比,证实模型可以很好地反映单轴受压状态下岩石和混凝土的应力、应变与声发射数的耦合关系

車載レンジセンサを用いた長大トンネルの3次元モデリングとその評価

Precise and accurate 3D model of a road structure is the basic information which can be utilized for various purposes, such as safety measures, 3D navigation, driving simulation, and reference data for autonomous driving. Generally, the 3D model of a tunnel where GPS signal is not available has been constructed based on positioning using gyro sensor, however, error accumulation becomes a considerable problem in the case of long tunnels. We propose a method to obtain geometrically optimal whole structure of a tunnel:(1) Acquire a set of partial structures by static scanning using a laser range sensor, which is mounted on the roof of a survey vehicle, and align them by 3D matching using edge feature. (2) Fix the absolute position of the data for both ends of the tunnel by GPS and align the rest data again. By applying this method, we succeeded to create the 3D digital model of Kanaya Tunnel in New Tomei Expressway, whose length is 4.6 km. For the comparison and evaluation of modeled tunnel, we present a system to evaluate the quality of the modeled tunnel comparing with the 2D CAD blueprint. This system can be described as following steps:(1)Extract the boundaries both from CAD blueprint and modeled tunnel to a 2D plane. (2)Transform the coordinate of modeled tunnel to the same coordinate as CAD blueprint. (3)Calculate the closest distance between the modeled tunnel boundaries and CAD boundaries. (4)Calculate the middle line of two data boundaries, and calculate the curvatures of both middle line, finally compare the curvature graph with the closest distance graph. We succeed creating a dense model of actual tunnel with a length of 4.6 km by geometric process. For the error evaluation, we did the curvature calculation and closest distance calculation. The closest distance of our modeled tunnel with 2D CAD data is about 50 centimeters on the west side, about 20 centimeters on the east side and about 4 meters around the big curve in the middle of tunnel. From this result ,we have three assumptions about the error factors, which can be described as follows, the uncertainty in central part, the rotation error around the big curve during the local alignment process, and the GPS positioning errors accumulated in the simultaneous alignment. From curvature analysis, we can see that the largest error is at the central part, and the error rate is about 0.1 percent, also the GPS points should not be fully fixed in global alignment. About our future work, we plan to increase our modeling accuracy and reduce errors at three parts. For data acquisition, we want to increase more density of our raw data, for local alignment, we want to use more other features besides edges for local alignment to reduces accumulated errors, lastly, for global alignment, we want to allow some freedom for GPS points to move slightly