排水管堵塞引起的高铁隧道结构变形与渗流场特征模拟试验研究

基于3D打印技术构建了高铁隧道结构及排水系统设施精细模型,提出了切实可行的隧道堵管模拟方法及模拟装置,依托典型病害案例开展了堵管病害相似模型模拟试验,探讨了在不同堵管条件、不同地层水头下隧道渗流场(隧道排水量、结构外水压力)及结构位移量的变化规律特征.研究结果表明:随堵塞程度加深,隧道排水量呈现先慢后快型下降趋势,具体为排水管堵塞率为50%前隧道排水量下降幅度较小,而堵塞率达50%后隧道排水量骤减直至不排水;底部结构隆起位移存在\"隧底>内轨>外轨\"的量值关系,且随堵塞程度加深隆起位移呈现先慢后快型增长趋势;受排水减少影响,堵管后结构外水压力逐步由\"隧底最大,拱顶、拱腰次之,墙脚最小\"的扇贝型分布转为\"静水压\"型分布;至全堵条件下地层水头40 m时试验位移结果与现场病害特征吻合良好,验证了上述模拟方法的可行性与有效性.研究成果以期为富水隧道堵管防治及类似病害评价提供借鉴与指导作用.     

建筑3D打印技术及材料的研究进展

3D打印技术在建筑领域的研究与应用逐渐成为世界范围内的热点研究课题之一,建筑3D打印材料的研究与开发是3D打印技术在建筑领域应用的重点和难点.本文回顾了3D打印技术的发展历程,在总结国内外建筑3D打印技术的基础上,重点介绍了建筑3D打印材料的研究状况和进展,并对目前建筑3D打印材料的应用和问题进行了概括,对建筑3D打印...     

3D打印技术在高铁隧道仰拱隆起病害模拟试验中的应用与研究

高铁隧道仰拱隆起病害频发,严重影响线路正常运营。提出一种用于高铁隧道变形致灾病害试验模拟的新方法,利用3D打印技术构建高铁隧道结构及附属设施精细模型,全方位考虑高铁隧道附属设施的工作状态,并系统介绍3D打印隧道模型的构件类型、打印材料及优选方法、打印流程等多方面内容;依托典型病害案例进行相似模型模拟试验,重现现场病害特征,探讨隧道排水量、结构外水压力和结构位移量的规律特征。研究结果表明:随地下水位的上升,隧道排水量与地下水位呈对数型增长关系;地下水位20 m后隧道排水量增量明显减缓、结构外水压力显著增加(尤其是隧底与拱顶)、底部结构隆起持续增长,且存在\"隧底>内轨>外轨\"的隆起量值特征;至地下水位50m时试验结果与现场病害特征吻合良好,验证了该方法的可行性与有效性。研究成果可为隧道病害及类似隧道模型试验的精细化模拟提供借鉴。     

混凝土3D打印技术的研究与应用进展

3D打印技术是一种热门的新兴技术,与传统技术相比,其更加系统,也更加便捷,已经在很多行业和领域得到应用.本文综合相关研究成果,阐述了混凝土3D打印技术的材料与工艺研究、3D打印混凝土的性能试验方法研究及混凝土3D打印技术的应用研究,并分析了3D打印技术现阶段存在的问题与不足,对混凝土3D打印技术的研究方向进行了展望.     

3D打印建筑技术应用研究

近年来,3D打印技术的快速发展,带动了其在建筑领域的研究及实践。新的建造技术是对传统技术的挑战和补充,同时促使了建筑设计、材料研发、计算机编程、机械设计等多方面的创新。本文通过一些3D打印建筑应用案例及设计的研究,分析本技术的特点,对3D打印建筑的发展进行展望。     

混凝土3D打印材料的性能与评价方法

3D打印技术的关键在于打印材料的性能,要求其具有良好的流动性、可塑性、挤出性、建造性且凝结时间可调,从而实现可连续打印、无坍塌;同时,还要求其硬化后具有较高的力学性能,以保证打印构建能承受自重及抵抗外力冲击。本文针对混凝土打印材料的性能及评价方法进行总结和分析,为混凝土3D打印技术的后续研究提供参考,并指出混凝土3D打印技术存在的挑战和未来的研究方向。     

原位建筑3D打印两层办公室的施工关键技术

总结了两层办公室项目的原位3D打印施工关键技术.设计开发了具有模块化、高精度、多功能等技术特点大型建筑3D打印机;开发了适合现场3D打印施工的专用添加剂,现场搅拌制备出性能优良的、适合现场施工的3D打印混凝土;提出了一种打印建筑竖向钢筋笼放置和连接方法,解决了打印混凝土结构构造柱根部节点与基础连接的施工难题;通过材料技...     

水泥基材料3D打印技术研究进展

3D打印技术是一种增材制造、快速成型技术,应用于建筑结构具有建造速度快、建造成本低、无模化施工和建筑垃圾少等优势.本文针对建筑结构的3D打印建造,介绍了三种适用的打印工艺,讨论了3D打印水泥基材料工作性能、力学性能与耐久性能的研究现状,对3D打印配筋增强构件的研究进展做了总结分析,对目前3D打印在建筑领域应用面临的问题...     

基于Flac3D软件的某路堑开挖稳定性分析

铁路路堑稳定性是铁路安全的一个重要保障。本文利用Flac3D软件．基于Mohr—Coulomb屈服准则,对某铁路路堑进行了数值模拟计算,以确定其应力、位移状态及塑性区分布情况．进而分析和评价路堑安全性,最后得出Flac3D软件在铁路路堑稳定性分析中应用的合理性和适用性。     

An approach to measure infill matric suction of irregular infilled rock joints under constant normal stiffness shearing

Rock joints infilled with sediments can strongly influence the strength of rock mass. As infilled joints often exist under unsaturated condition, this study investigated the influence of matric suction of infill on the overall joint shear strength. A novel technique that allows direct measurement of matric suction of infill using high capacity tensiometers (HCTs) during direct shear of infilled joints under constant normal stiffness (CNS) is described. The CNS apparatus was modified to accommodate the HCT and the procedure is explained in detail. Joint specimens were simulated by gypsum plaster using three-dimensional (3D) printed surface moulds, and filled with kaolin and sand mixture prepared at different water contents. Shear behaviours of both planar infilled joints and rough joints having joint roughness coefficients (JRCs) of 8–10 and 18–20 with the ratios of infill thickness to asperity height (t/a) equal to 0.5 were investigated. Matric suction shows predominantly unimodal behaviour during shearing of both planar and rough joints, which is closely associated with the variation of unloading rate and volumetric changes of the infill material. As expected, two-peak behaviour was observed for the rough joints and both peaks increased with the increase of infill matric suction. The results suggest that the contribution of matric suction of infill on the joint peak normalised shear stress is relatively independent of the joint roughness.     

建筑3D打印力学性能研究综述

3D打印试样的力学性能具有各向异性,其抗压强度与抗折强度的测试方法与传统混凝土相似,但需经过加工与切割,这会造成3D打印试件的变化。在3D打印力学性能中,层间强度最差,大多数试验采用与劈裂强度相似的方法进行测量。由于需加入增稠剂等来调节原材料的流动性,这会影响3D打印试样的力学性能。3D打印接触空气的面积较大,容易造成收缩开裂,可通过加入纤维等来减少收缩。在实际工程中,也可以通过预埋支架等来提高3D打印试样的力学性能。     

基坑支护后的监测与分析

根据广东省某基坑支护现场监测的实测数据资料,采用Plaxis 3D Tunnel三维隧道软件模拟了基坑支护后的变形,通过实际监测进一步验证了分析模拟的正确性,并分析了基坑开挖对周围建筑物的影响,为边坡稳定性分析奠定了理论基础。     

A state-of-the-art review of automated extraction of rock mass discontinuity characteristics using three-dimensional surface models

In the last two decades, significant research has been conducted in the field of automated extraction of rock mass discontinuity characteristics from three-dimensional (3D) models. This provides several methodologies for acquiring discontinuity measurements from 3D models, such as point clouds generated using laser scanning or photogrammetry. However, even with numerous automated and semi-automated methods presented in the literature, there is not one single method that can automatically characterize discontinuities accurately in a minimum of time. In this paper, we critically review all the existing methods proposed in the literature for the extraction of discontinuity characteristics such as joint sets and orientations, persistence, joint spacing, roughness and block size using point clouds, digital elevation maps, or meshes. As a result of this review, we identify the strengths and drawbacks of each method used for extracting those characteristics. We found that the approaches based on voxels and region growing are superior in extracting joint planes from 3D point clouds. Normal tensor voting with trace growth algorithm is a robust method for measuring joint trace length from 3D meshes. Spacing is estimated by calculating the perpendicular distance between joint planes. Several independent roughness indices are presented to quantify roughness from 3D surface models, but there is a need to incorporate these indices into automated methodologies. There is a lack of efficient algorithms for direct computation of block size from 3D rock mass surface models.     

A simplified three-dimensional extension of Hoek-Brown strength criterion

The Hoek-Brown(HB) strength criterion has been applied widely in a large number of projects around the world.However,this criterion ignores the intermediate principal stress σ_2.Many evidences have demonstrated that the rock strength is dependent on σ_2. Thus it is necessary to extend the HB criterion into a three-dimensional(3D) form.In this study,the effect of σ_2 on the strength of rocks is identified by reviewing the true triaxial tests of various rock types reported in the literature.A simple 3D strength criterion is developed.The modified criterion is verified by the true triaxial tests of 13 rock types.The results indicate that the modified criterion can achieve a good fit to most of rock types.It can represent a series of criteria as b varies.For comparisons,several existing 3D versions of the HB criterion are selected to predict the strengths of these rock types.It is indicated that the proposed criterion works better than other criteria.A substantial relationship between parameter b and the unconfined compressive strength is established,which guarantees that the proposed criterion can still work well even in the absence of true triaxial test data.     

3D打印混凝土材料的研究现状与展望

随着3D打印技术的快速发展和3D打印建筑材料的研发,3D打印技术在建筑行业得到了迅速发展,它是一种基于增材制造的建造技术,而混凝土是该技术最常用的打印材料。重点阐述了3D建筑打印技术,3D打印混凝土材料的可建造性、临界失效时间、层间黏结强度、干燥收缩率等性能要求,总结了3D打印混凝土材料国内外研究现状,最后着重阐述了3D打印混凝土施工技术中存在的问题,并对其发展前景进行了展望,希望为以后该方向此类问题的研究提供借鉴。     

砂土颗粒形状量化及其对力学指标的影响分析

颗粒形状是影响砂土宏观力学指标的重要因素。提出一种修正的三维形状系数