浅埋暗挖技术在南平市天台隧道工程施工中的应用          下载免费PDF全文

李耀卿 《探矿工程》2005,32(12):56-58

主要介绍了在Ⅱ、Ⅲ类围岩中施工城市浅埋隧道的施工技术，以“短开挖、快封闭、强支护、勤量测”为指导，将隧道分成上、下两个台阶进行开挖，及时进行初期支护，保证施工始终处于安全状态。  相似文献   

西藏直孔水电站大坝混凝土防渗墙超前支护成槽试验研究及施工     

马邦凯  牟兴华  蔡海燕 《探矿工程》2005,32(12):3-5

在西藏直孔水电站松散砂卵石地层混凝土防渗墙成槽施工中，结合坝基水文地质及工程地质特点，创造性地提出了超前支护成槽方案，通过三维应力模拟和渗透试验，结合现场生产试验，对原方案更进一步完善，在施工中加以应用获得了成功。  相似文献   

Ensemble prediction of regional droughts using climate inputs and the SVM–copula approach          下载免费PDF全文

Poulomi Ganguli  M. Janga Reddy 《水文研究》2014,28(19):4989-5009

In this study, the climate teleconnections with meteorological droughts are analysed and used to develop ensemble drought prediction models using a support vector machine (SVM)–copula approach over Western Rajasthan (India). The meteorological droughts are identified using the Standardized Precipitation Index (SPI). In the analysis of large‐scale climate forcing represented by climate indices such as El Niño Southern Oscillation, Indian Ocean Dipole Mode and Atlantic Multidecadal Oscillation on regional droughts, it is found that regional droughts exhibits interannual as well as interdecadal variability. On the basis of potential teleconnections between regional droughts and climate indices, SPI‐based drought forecasting models are developed with up to 3 months' lead time. As traditional statistical forecast models are unable to capture nonlinearity and nonstationarity associated with drought forecasts, a machine learning technique, namely, support vector regression (SVR), is adopted to forecast the drought index, and the copula method is used to model the joint distribution of observed and predicted drought index. The copula‐based conditional distribution of an observed drought index conditioned on predicted drought index is utilized to simulate ensembles of drought forecasts. Two variants of drought forecast models are developed, namely a single model for all the periods in a year and separate models for each of the four seasons in a year. The performance of developed models is validated for predicting drought time series for 10 years' data. Improvement in ensemble prediction of drought indices is observed for combined seasonal model over the single model without seasonal partitions. The results show that the proposed SVM–copula approach improves the drought prediction capability and provides estimation of uncertainty associated with drought predictions. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Parallelized combined finite-discrete element (FDEM) procedure using multi-GPU with CUDA     

Quansheng Liu  Weiqin Wang  Hao Ma 《国际地质力学数值与分析法杂志》2020,44(2):208-238

This paper focuses on the efficiency of finite discrete element method (FDEM) algorithmic procedures in massive computers and analyzes the time-consuming part of contact detection and interaction computations in the numerical solution. A detailed operable GPU parallel procedure was designed for the element node force calculation, contact detection, and contact interaction with thread allocation and data access based on the CUDA computing. The emphasis is on the parallel optimization of time-consuming contact detection based on load balance and GPU architecture. A CUDA FDEM parallel program was developed with the overall speedup ratio over 53 times after the fracture from the efficiency and fidelity performance test of models of in situ stress, UCS, and BD simulations in Intel i7-7700K CPU and the NVIDIA TITAN Z GPU. The CUDA FDEM parallel computing improves the computational efficiency significantly compared with the CPU-based ones with the same reliability, providing conditions for achieving larger-scale simulations of fracture.  相似文献   

Site characterization model using least‐square support vector machine and relevance vector machine based on corrected SPT data (Nc)     

Pijush Samui  T. G. Sitharam 《国际地质力学数值与分析法杂志》2010,34(7):755-770

Statistical learning algorithms provide a viable framework for geotechnical engineering modeling. This paper describes two statistical learning algorithms applied for site characterization modeling based on standard penetration test (SPT) data. More than 2700 field SPT values (N) have been collected from 766 boreholes spread over an area of 220 sqkm area in Bangalore. To get N corrected value (N_c), N values have been corrected (N_c) for different parameters such as overburden stress, size of borehole, type of sampler, length of connecting rod, etc. In three‐dimensional site characterization model, the function N_c=N_c (X, Y, Z), where X, Y and Z are the coordinates of a point corresponding to N_c value, is to be approximated in which N_c value at any half‐space point in Bangalore can be determined. The first algorithm uses least‐square support vector machine (LSSVM), which is related to a ridge regression type of support vector machine. The second algorithm uses relevance vector machine (RVM), which combines the strengths of kernel‐based methods and Bayesian theory to establish the relationships between a set of input vectors and a desired output. The paper also presents the comparative study between the developed LSSVM and RVM model for site characterization. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

基于CityEngine的三维城市规划设计与研究     

李宏旭  杨李东 《测绘与空间地理信息》2016,(5):55-57

城市规划领域越来越需要三维建模技术的支持。CityEngine作为一种新型的三维建模软件,不仅可以批量生成规划模型,还可以用来辅助三维城市规划设计。本文基于CityEngine规则建模方法,实现了规划方案对比、建筑体量调整、规划指标计算等功能,通过对某小区进行实际建模验证,证明了CityEngine可以为城市规划者们提供新的思路,为城市设计和城市管理提供决策支持。  相似文献   

灰色组合模型在滑坡变形监测中的应用分析     

贾勇帅  魏超  刘欣  杨超 《测绘与空间地理信息》2016,(9):210-213

在GM(1,1)模型的基础上,主要研究了改进残差修正模型、灰色BP神经网络模型、灰色线性回归模型在变形数据的预计精度,并且结合实例分析了不同灰色组合模型在滑坡变形预计的精度以及优缺点。  相似文献   

豫西地区雷暴预警预报系统构建方法研究     

李振锋  付伟基  陈红霞 《气象与环境科学》2016,39(4):126-134

目前,基层台站在雷暴预警预报中主要依赖传统经验预报方法,而对卫星云图、大气电场、多普勒雷达回波和高分辨率数值预报产品等资料释用水平不高,存在主观定性分析多、客观定量计算少等不足。依托现有气象资料和雷暴预报方法,以雷暴预警预报系统构建为目标,从气象数据仓库构建、支持向量机雷暴预报、相似预报雷暴预报、Poor Man集合预报技术和多源数据融合分析等方面,探讨了雷暴预警预报系统构建方法,实现了雷暴中期预测、短期预报和短时临近预警三个层次的预报功能,解决了气象资料庞杂难以管理、数值预报产品释用水平不高、数值预报结果存在"跃变"、多源数据融合分析缺乏手段等问题,提高了基层台站雷暴预报工作效率和预报水平,同时也为其他地区类似系统构建提供了参考。  相似文献   

回归-Elman网络在矿坝变形预测中的应用     

王祖顺  韩吉德  王春青 《测绘工程》2016,25(1):39-42

金矿开展矿坝的变形监测工作,引入多层递阶回归分析模型,有较高的预测精度,但方法较繁琐,计算较复杂。由于变形数据可分离成趋势项与随机项,趋势项可用多元线性回归良好地拟合;随机项的预测,文中采用Elman网络建模计算,最后利用矿坝的实测高程位移数据进行验证,并与多层递阶回归进行比较。结果表明:回归-Elman网络模型比多层递阶回归的预测精度更高,效果更好,且方法简洁实用性强。  相似文献   

支持向量机的车载雷达点云目标识别     

李海亭  王厚之  李艳红  汪汇兵 《测绘科学》2016,41(5):45-49

为了进一步研究移动测量系统的数据处理问题,该文根据点云的基本特征,归纳了由7个特征构成的点云原始特征向量,在此基础上,结合语义环境构建了由17个特征构成的点云扩展特征向量,并采用支持向量机模型对车载LiDAR点云进行行道树点云识别的一系列实验。实验中采用粒子群优化算法和遗传算法对支持向量机进行参数寻优;采用不同特征向量和不同数目样本对点云进行学习和目标识别;分析了特征向量的学习曲线和识别精度。实验结果表明,支持向量机模型能够在行道树点云识别中取得较高的精度。  相似文献