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基于布里渊光时域反射计(BOTDR)的工作原理,介绍了光纤测试技术是近年来国际上研发成功的一项新型的分布式光电传感技术。实践证明通过该技术,将传感光纤按照一定的工艺粘贴在埋置于土体中的测斜管上,由传感光纤实测的应变分布,可以实现深部土体水平位移的在线监测。 相似文献
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The Crossrail project currently under construction in Central London has been described asThe Big Dig on Steroids,obviously referencing the Central Artery/Tunnel project in Boston completed in 2007.To address the multiple demands for timely construction performance monitoring,Crossrail envisioned the underground construction information management system(UCIMS)to monitor construction progress and structural health along the entire route,with a network of geotechnical instruments(i.e.slope inclinometers,extensometers,piezometers,etc.)and tunnel boring machine(TBM)position information.The UCIMS is a geospatially referenced relational database that was developed using an open source geographic information system(GIS)that allowed all stakeholders near immediate feedback of construction performance.The purpose of this article is to provide a brief history of geotechnical and structural monitoring software,to describe the structure and operation of the UCIMS,and to demonstrate how the functionality afforded by this system provided the requisite feedback to the stakeholders.Examples will be given regarding how the data management and visualization concepts incorporated into the UCIMS advanced the geotechnical construction industry. 相似文献
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岩土工程反分析的初步探讨 总被引:1,自引:0,他引:1
介绍了岩土工程反分析的定义、特点及本质,重点讨论了位移反分析的概念、分类、发展现状,指出了反分析存在的一些问题及未来的主要发展方向。 相似文献
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论述了土工格栅的性能,分析了土工格栅加筋路堤中筋材与土的相互作用,并介绍了土工格栅加筋机理的理论依据和试验分析,指出土工格栅是一种良好的路用加筋材料,其加筋路堤的作用主要通过土工格栅筋材的拉力激发来实现。 相似文献
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针对岩土参数小样本下t分布法区间估计较宽将导致工程设计偏于保守的问题,根据描述土体固有变异性的c,?总体开展小样本随机取样勘察模拟,运用Bootstrap法进行数据重构得到区间估计和点估计结果,对比与t分布法所得参数估计的差异。基于充足次数重复抽样构建的参数估计空间,分析与之映射的边坡稳定安全系数离散特征。研究表明:对应于同一置信水平,能充分利用小样本经验分布信息的Bootstrap法可有效收窄c,?均值置信区间,保证率下限值较传统t分布法结果更接近真值;虽然2种方法得到点估计结果的均值和方差相同,即对应的边坡稳定可靠指标相等,但采用Bootstrap法保证率下限值计算的边坡稳定安全系数均值相对较大,离散性更小,且这种改善效果随参数变异水平上升愈加明显;在保证相同可靠度条件下,Bootstrap法能更合理地对小样本统计不确定性导致的边坡安全风险进行补偿。 相似文献
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Bhatkar T. Mandal A. Kumar C. Usmani A. 《Bulletin of Engineering Geology and the Environment》2017,76(3):1209-1216
Bulletin of Engineering Geology and the Environment - The present report highlights the methods used to monitor the rock mass behavior and performance of a cavern during excavation in order to... 相似文献
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岩土地质抗浮锚杆数值模拟分析 总被引:2,自引:0,他引:2
结合青岛市王家下河社区安置项目,采用ANSYS有限元软件对岩土地质条件下抗浮锚杆的受力机理进行了分析,并证明在风化岩层上覆薄弱土层的地基条件下,上部土层的锚杆抗拔力设计值为通常情况下锚杆抗拔力设计值的42.9%. 相似文献
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结合建筑工程中常遇的岩土工程问题,对建筑岩土工程勘察的内容进行了简要的概述,并对建筑岩土工程勘察的要点进行了分析,从而确保勘察的准确性。 相似文献
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Assaf Klar Raphael Linker 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2010,25(5):575-586
Cross-borders smuggling tunnels enable unmonitored movement of people, drugs and weapons and pose a very serious threat to homeland security. Recent advances in strain measurements using optical fibers allow the development of smart underground security fences that could detect the excavation of smuggling tunnels. This paper presents the first stages in the development of such a fence using Brillouin optical time domain reflectometry (BOTDR). Two fiber optic layouts are considered and evaluated in a feasibility study that includes evaluation of false detection and sensitivity: (1) horizontally laid fiber buried at a shallow depth, and (2) fibers embedded in vertical mini-piles. In the simulation study, two different ground displacement models are used in order to evaluate the robustness of the system against imperfect modeling. In both cases, soil–fiber and soil-structure interactions are considered. Measurement errors, and surface disturbances (obtained from a field test) are also included in the calibration and validation stages of the system. The proposed detection system is based on wavelet decomposition of the BOTDR signal, followed by a neural network that is trained to recognize the tunnel signature in the wavelet coefficients. The results indicate that the proposed system is capable of detecting even small tunnel (0.5 m diameter) as deep as 20 m (under the horizontal fiber) or as far as 10 m aside from the mini-pile (vertical fiber), if the volume loss is greater than 0.5%. 相似文献
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Spatial variability (randomness, correlation, and singularity) within the geotechnical parameters of complicated geological movements influences the estimation quality that depends on how well mathematical tools can account for variability through limited observations of a spatial field. Classical statistical methods depict randomness well, but cannot account for the problems associated with spatial correlations. Geostatistical methods such as ordinary Kriging (OK), universal Kriging (UK), and co-Kriging (CK) can produce predictions based on spatial auto-correlation and cross-correlation, but are always accompanied by average smoothing effects; a local singularity created by nonlinear geo-processes, therefore, requires special methods to be properly evaluated. In this study, a shallow load-bearing stratum of silt clay (length = 525 m, width = 80 m) at the former 2010 Expo Park in Shanghai was explored by performing 42 borehole laboratory experiments, which provided the key geotechnical parameters: the cohesion coefficient (\( C \), in kPa), the friction angle (\( \varphi \), in o), and the compression modulus (\( E_{\text{S}} \), in MPa). First, Kriging methods such as OK, UK, and CK estimated these geotechnical parameters, then a multi-fractal analysis was employed to measure the local singularity. Cross-validation illustrates that multi-fractal analysis has the ability to depict a local anomaly, and further that the auxiliary information utilized in CK improves spatial estimation accuracy. 相似文献
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岩土材料在外荷载作用下其变形通常表现出时间与空间分布上的非均匀性特征,在应用DSCM(数字散斑相关方法)进行图像像素测点的相关搜索过程中,传统方法通常对于全部试验阶段的图像和同一幅图像上的所有测点均采用相同的搜索范围,显然,这是一个虽然简单但效率很低的图像搜索分析方法。提出一种依据参考网格的测点动态范围搜索方法(简称PDSS),即首先利用常规搜索方法分析获得一个间距较大且覆盖正式分析范围的测点网格的位移,然后以其作为正式图像测点分析的参考网格,最后,对任一测点,以其所在的参考单元节点的最大位移作为该测点的搜索范围值,从而可实现与测点变形大小相适应的动态范围搜索。PDSS方法本质上是通过减少相关分析的像素点数量来大幅提高图像分析速度。试验检验结果表明,PDSS方法相对于普通方法的图像分析速度通常可提高10倍左右。研究成果解决了具有时空非均匀变形特征的岩土材料DSCM的快速优化分析问题,可进一步提高DSCM在岩土材料变形量测中的应用技术水平。 相似文献
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Hongming Tian Weizhong Chen Diansen Yang Yonghao Dai Jianping Yang 《Bulletin of Engineering Geology and the Environment》2016,75(1):239-249
The back analysis method has been widely used as an indirect method of determining geotechnical parameters based on field measurements. The number of parameters and their initial values greatly influence the reliability and efficiency of back analysis. Therefore, sensitivity analysis is often employed to select high sensitivity parameters that have more greater impact on measured back analysis values. The orthogonal design method was first utilized to select geotechnical parameters for back analysis. The optimized parameter values obtained from an orthogonal design table can be used as the initial back analysis values, so as to avoid optimisation algorithm searching in local parameter spaces. By introducing a penalty function to the objective function, back analysis of the geotechnical parameters is changed into an unconstrained optimisation problem, whereby the Nelder–Mead method can then be employed. To verify the feasibility of the proposed back analysis method, a case study was conducted to determine the rock mass parameters for the Houziyan underground powerhouse complex. 相似文献
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基于注浆技术在岩土施工工程项目中的重要性,对不同的注浆法进行了分类介绍,并阐述了注浆技术在防渗治水与地基加固工程中的应用技术,对注浆过程中出现的串孔、冒浆、地面隆起等情况提出了处理措施,以达到良好的施工效果。 相似文献