浮法玻璃过渡辊台辊子姿态的非接触精密检测     

刘尚国  于胜文  郑文华 《测绘科学》2010,35(6):145-146,128

采用由两台Leica TM5100A电子经纬仪构成的Axyz工业测量系统,对某浮法玻璃生产线过渡辊台、渣箱及辊子的平行度及其相对高差进行了非接触精密检测。在没有已知控制点的情况下,借助激光发射器投射激光点,测定高温目标和运转目标上的检测点三维坐标。通过坐标系转换、拟合计算等,分析其平行度、垂直度、相对高差等姿态信息,为辊子的维护工作提供可靠的调整数据。检测结果表明,在20m范围内的高温嘈杂环境下,能够满足其亚毫米级的测量精度要求。  相似文献   

A numerical model of wave overtopping on seadikes     

Thieu Quang Tuan  Hocine Oumeraci 《Coastal Engineering》2010

This paper describes the development of a numerical model for wave overtopping on seadikes. The model is based on the flux-conservative form of the nonlinear shallow water equations (NLSW) solved with a high order total variation diminishing (TVD), Roe-type scheme. The goal is to reliably predict the hydrodynamics of wave overtopping on the dike crest and along the inner slope, necessary for the breach modelling of seadikes. Besides the mean overtopping rate, the capability of simulating individual overtopping events is also required. It is shown theoretically that the effect of wave breaking through the drastic motion of surface rollers in the surfzone is not sufficiently described by the conventional nonlinear shallow water equations, neglecting wave setup from the mean water level and thus markedly reducing the model predictive capacity for wave overtopping. This is significantly improved by including an additional source term associated with the roller energy dissipation in the depth-averaged momentum equation. The developed model has been validated against four existing laboratory datasets of wave overtopping on dikes. The first two sets are to validate the roller term performance in improving the model prediction of wave overtopping of breaking waves. The last two sets are to test the model performance under more complex but realistic hydraulic and slope geometric conditions. The results confirm the merit of the supplemented roller term and also demonstrate that the model is robust and reliable for the prediction of wave overtopping on seadikes.  相似文献   

Large-wave simulation of three-dimensional,cross-shore and oblique,spilling breaking on constant slope beach     

Aggelos S. Dimakopoulos  Athanassios A. Dimas 《Coastal Engineering》2011

In this work, the large-wave simulation (LWS) method is adapted for application in spilling wave breaking over a constant slope beach. According to LWS, large scales of velocities, pressure and free-surface elevation are numerically resolved, while the corresponding unresolved scale effects are taken into consideration by a subgrid scale (SGS) model for wave and eddy stresses. The model may be not fully applicable in very shallow water, close to the shoreline, where the unresolved, turbulent, free-surface oscillation is of the same order with the water depth. Time integration of the Euler equations is achieved by a two-stage fractional scheme, combined with a hybrid scheme for spatial discretization, consisting of finite difference and pseudospectral approximation methods. Model parameters are calibrated by comparison to available experimental data of free-surface elevation and velocities in the surf zone for cross-shore incoming waves. The action of the wave SGS stresses in the outer coastal and surf zones initiates breaking and generates appropriate vorticity, in the form of an eddy structure (surface roller), at the breaking wavefront. At incipient breaking, both advection and gravity contribute to the vorticity flux at the free surface, while only after the full development of the surface roller, the effect of advection becomes stronger. The SGS model is also utilized to simulate propagation, refraction and breaking of oblique incoming waves. The gradual breaking and dissipation of wave crestlines and the surface roller structure along the breaking wavefront are automatically captured without any empirical input, such as data for the roller shape or the wave propagation angle at breaking.  相似文献   

基于新表面理论的TBM破岩效率评价指标     

闫长斌  李高留  陈健  李严  杨延栋  杨风威  杨继华 《岩土力学》2023,(4):1153-1164

岩碴是岩-机作用的直接产物,也是评价隧道掘进机（TBM）破岩效率和优化TBM掘进参数的有效指标。依托兰州水源地建设工程和龙岩万安溪引水工程,开展不同岩性条件下TBM岩碴筛分试验,得到了岩碴粒径分布规律。基于新表面理论,从滚刀破岩能量转化角度出发,提出了一种新的TBM破岩效率评价指标。基于岩碴粒径分布规律和TBM掘进参数统计,探讨了新表面理论指标与比能、岩碴粗糙度指数之间的关系,指出了新表面理论指标在反映岩碴破碎程度和评价TBM破岩效率方面的优势。对新表面理论指标与TBM掘进推力以及刀间距s与贯入度p的比值进行回归分析,得到了硬岩（围岩等级为Ⅱ级）和软岩（围岩等级为III级）掘进条件下的TBM最优掘进推力和s/p取值区间。研究表明：（1）新表面理论指标符合岩石破碎学原理,可准确评价TBM破岩效率。岩碴越是破碎,新表面理论指标越大,掘进能耗越高,此时TBM破岩效率相对较低。（2）新表面理论指标与比能、岩碴粗糙度指数均具有良好的线性相关关系。岩碴越是破碎,破碎单位体积岩石的能量消耗越大,新表面理论指标越大,对应的粗糙度指数越小。软岩掘进条件下TBM掘进比能低于硬岩,而岩碴破碎程度高于硬岩。（...  相似文献   

灰土挤密桩处理黄土湿陷工程问题分析          下载免费PDF全文

梁东  王刚  王华  李卫华 《探矿工程》2015,42(2):82-84

郑州豫翠园工程灰土挤密桩处理黄土湿陷施工中,消除黄土湿陷性的效果不好,施工后个别层位仍为轻微湿陷。通过对黄土湿陷机理、灰土挤密桩处理湿陷原理以及该工程具体问题的分析,认为灰土桩成孔方法不对以及挤密冲击力不够是导致效果不好的主要原因。将挤密桩成孔调整为冲击挤密成孔工艺,回填夯实灰土的冲击锤质量由100 kg增加到200 kg以增大冲击力,场地各土层的黄土湿陷现象全部消除,处理效果良好。  相似文献   

A combined neural network/gradient‐based approach for the identification of constitutive model parameters using self‐boring pressuremeter tests     

Rafał F. Obrzud  Laurent Vulliet  Andrzej Truty 《国际地质力学数值与分析法杂志》2009,33(6):817-849

This paper presents a numerical procedure of material parameter identification for the coupled hydro‐mechanical boundary value problem (BVP) of the self‐boring pressuremeter test (SBPT) in clay. First, the neural network (NN) technique is applied to obtain an initial estimate of model parameters, taking into account the possible drainage conditions during the expansion test. This technique is used to avoid potential pitfalls related to the conventional gradient‐based optimization techniques, considered here as a corrector that improves predicted parameters. Parameter identification based on measurements obtained through the pressuremeter expansion test and two types of holding tests is illustrated on the Modified Cam clay model. NNs are trained using a set of test samples, which are generated by means of finite element simulations of SBPT. The measurements obtained through expansion and consolidation tests are normalized so that NN predictors operate independently of the testing depth. Examples of parameter determination are demonstrated on both numerical and field data. The efficiency of the combined parameter identification in terms of accuracy, effectiveness and computational effort is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

非开挖铺管导向钻进中的事故处理   总被引：2，自引：0，他引：2  

史晓亮  李粮纲 《地质与勘探》2000,36(2):60-62

根据导向钻进法在实际管线铺设施工中遇到的孔内事故 ,阐述了处理常见孔内事故的措施 ,并提出了避免事故发生的建议。  相似文献   

Environmental factors shaping boring sponge assemblages at Mexican Pacific coral reefs     

Héctor Nava  José Luis Carballo 《Marine Ecology》2013,34(3):269-279

Recent studies suggest a future increase in sponge bioerosion as an outcome of coral reef decline around the world. However, the factors that shape boring sponge assemblages in coral reefs are not currently well understood. This work presents the results of a 17‐month assessment of the presence and species richness of boring sponges in fragments collected from living corals, dead coral reef matrix and coral rubble from Punta de Mita and Isabel Island, two coral reefs from the central coast of the Mexican Pacific Ocean. Both localities have a high cover of dead corals generated by past El Niño Southern Oscillation events, but Punta de Mita was also highly exposed to anthropogenic impacts. Additionally, environmental factors (water transparency, water movement, temperature, sediment deposition, SST, and chlorophyll concentration) were assessed to test the hypothesis that environmental conditions which are potentially harmful for corals can enhance sponge bioerosion. Isabel Island and Punta de Mita showed a similar species richness (13 and 11 species, respectively) but boring sponge presence in both live and dead corals was higher at Isabel Island (57.6%) than at Punta de Mita (35.7%). The same result was obtained when each type of substrate was analysed separately: dead coral reef matrix (81.3% versus 55.5%), coral rubble (47.7% versus 20.0%) and living corals (43.7% versus 31.7%). A principal components analysis showed a higher environmental heterogeneity at Punta de Mita, as well as important environmental differences between Punta de Mita and Isabel Island, due to sediment deposition (2.0 versus 0.2 kg·m^?2·d^?1) and water movement (24.5% versus 20.5% plaster dissolution day^?1), that were also negatively correlated with boring sponge presence (r = ?0.7). By analysing the boring sponge assemblage, we found that environmental settings, together with habitat availability (i.e., dead coral substrate) differentiated assemblage structure at both localities. Major structural differences were largely due to species such as Cliona vermifera, Cliona tropicalis and Aka cryptica. In conclusion, factors such as habitat availability favored the presence of boring sponges but some environmental factors such as abrasion resulting from moving sediment acted restrictively, and exerted a major role in structuring boring sponge assemblages in the Mexican Pacific.  相似文献   

Prediction model of tunnel boring machine performance by ensemble neural networks     

《Geomechanics and Geoengineering》2013,8(2):123-128

The penetration rate of a tunnel boring machine (TBM) depends on many factors ranging from the machine design to the geological properties. Therefore it may not be possible to capture this complex relationship in an explicit mathematical expression. In this paper, we propose an ensemble neural network (ENN) to predict TBM performance. Based on site data, a four-parameter ENN model for the prediction of the specific rock mass boreability index is constructed. Such a neural-network-based model has the advantages of taking into account the uncertainties embedded in the site data and making appropriate inferences using very limited data via the re-sampling technique. The ENN-based prediction model is compared with a non-linear regression model derived from the same four parameters. The ENN model outperforms the non-linear regression model.  相似文献   

软弱砂岩骨料碾压混凝土的配制及其特性研究          下载免费PDF全文

刘伟宝  陆采荣  梅国兴  戈雪良  王珩  杨虎 《海洋工程》2014,32(6):105-110

在东南亚和我国西南地区由于缺乏合适的原材料,必须采用软弱骨料配制混凝土。以东南亚某工程现场的软弱砂岩为原材料,开展碾压混凝土配制和性能试验工作,探讨了该骨料配制碾压混凝土的可行性。采用软化系数为0.71的软弱砂岩,配制强度等级分别为C18020的二级配碾压混凝土和C1807.5的三级配碾压混凝土。结果表明,采用该砂岩骨料可以配制出满足强度要求的碾压混凝土,其用水量比常规骨料高15~20 kg/m3,拌和物密度和抗压弹模较低。其中,二级配碾压混凝土采用50%粉煤灰掺量、0.55水胶比;三级配碾压混凝土采用60%粉煤灰掺量、0.65水胶比。骨料抗碾压破碎模拟试验表明该骨料在碾压过程中破坏程度很低,说明采用该软弱骨料配制碾压混凝土具有可行性。  相似文献