Optimization of artificial ground freezing in tunneling in the presence of seepage flow     

《Computers and Geotechnics》2016

Artificial ground freezing is an environmentally friendly technique to provide temporary excavation support and groundwater control during tunnel construction under difficult geological and hydrological ground conditions. Evidently, groundwater flow has a considerable influence on the freezing process. Large seepage flow may lead to large freezing times or even may prevent the formation of a closed frozen soil body. For safe and economic design of freezing operations, this paper presents a coupled thermo-hydraulic finite element model for freezing soils integrated within an optimization algorithm using the Ant Colony Optimization (ACO) technique to optimize ground freezing in tunneling by finding the optimal positions of the freeze pipe, considering seepage flow. The simulation model considers solid particles, liquid water and crystal ice as separate phases, and the mixture temperature and liquid pressure as primary field variables. Through two fundamental physical laws and corresponding state equations, the model captures the most relevant couplings between the phase transition associated with latent heat effect, and the liquid transport within the pores. The numerical model is validated by means of laboratory results considering different scenarios for seepage flow. As demonstrated in numerical simulations of ground freezing in tunneling in the presence of seepage flow connected with the ACO optimization algorithm, the optimized arrangement of the freeze pipes may lead to a substantial reduction of the freezing time and of energy costs.  相似文献   

平面度优化计算研究     

何真 《广东海洋大学学报》1994,(1)

提出了平面度的优化计算方法，并对其中的有关理论问题进行了研究。用这种方法能求出满足“最小区域”的平面度值。  相似文献   

调谐质量阻尼器的优化分析   总被引：7，自引：0，他引：7  

林均岐  王云剑 《地震工程与工程振动》1996,16(1):116-121

本文根据双自由度系统的随机反应，推导了设置调谐质量阻尼器的单自由度系统的运动方程，求出了白噪声基底输入时，设置ＴＭＤ的单自由度系统的反应方差与未设置ＴＭＤ的单自由度系统的反应方差之比，并采用模式搜索法对其进行优化方法，得到了ＴＭＤ系统的最佳减振效果以及相应的ＴＭＤ的参数取值，本文的分析表明，ＴＭＤ系统对减小白噪声基底输入的单自由度系统的随机反应是十分有效的。  相似文献   

Anchor deployment for deep water floating offshore equipments   总被引：1，自引：0，他引：1  

O. B. Augusto  B. L. Andrade 《Ocean Engineering》2003,30(5):611-624

In this work a planning methodology for deep water anchor deployment in offshore platforms and floating production systems aiming at operational resources optimization is explored, by minimizing a multi criteria objective function. As an additional advantage provided by the proposed methodology, planning automation is achieved. Planning automation overcomes the traditional way, using a trial error basis. With it, an engineer, using an anchoring software, decides how much work wire and anchoring line must be paid out from both the floating system and the tug boat. Additionally, he decides which horizontal force must be applied to the line, trying to settle the anchor on a previously defined target on the ocean floor.  相似文献   

Optimization and modeling of boric acid extraction from colemanite in water saturated with carbon dioxide and sulphur dioxide gases     

Zafer Ekinci  Enes ŞayanAyşe Vildan Beşe  Osman Nuri Ata 《International Journal of Mineral Processing》2007

In this study, the boric acid extraction from colemanite ore in aqueous media saturated by CO₂ and SO₂ gases was studied and the effects of relevant parameters, namely; reaction temperature, solid-to-liquid ratio, mean particle size, stirring speed and reaction time have been investigated on the boric acid extraction from colemanite ore by using the fractional factorial design and central composite design methods. The chosen experimental parameter levels were as follows: reaction temperature, 11.4–58.6 °C; solid-to-liquid ratio, 0.0685–0.1315 g/mL; mean particle size, 0.2835–3 mm; stirring speed, 107–893 rpm; reaction time, 7.125–22.875 min. A model has been developed between the boric acid extraction efficiency from colemanite ore and relevant parameters by means of variance analysis by using the matlab computer software and the obtained model was used to determine optimum conditions. The optimum conditions were found to be as follows: reaction temperature, 41 °C; solid-to-liquid ratio, 0.0685 g/mL; mean particle size, 0.2835 mm; stirring speed, 266 rpm; reaction time, 7 min. The calculated boric acid extraction efficiency from colemanite ore was approximately 99.9% under the optimum conditions.  相似文献   

Theis解析模型的数值解及其在MatLab中的实现     

李林子  朱国荣  江思珉  闵望 《江苏地质》2007,31(3):242-246

讨论了如何应用数值积分方法求解含水层中地下水非稳定流抽水试验的解析模型以获得含水层的水文地质参数,并以Theis公式为例讨论求解原理。引入了MatLab的数值积分工具和优化工具,轻松实现了对水文地质参数的求解,此举既保证了解的可靠性和唯一性,也大大提高了方法的可操作性。最后以一个具体的承压水非稳定流抽水试验为例验证了这个方法,所得的结果与应用配线法得到的结果基本一致,从而肯定了方法的应用价值。研究结果尽管是针对Theis模型进行的,但求解原理同样适用于其他各种模型。  相似文献   

Using beamforming for the global network location     

V. Pinsky 《Physics of the Earth and Planetary Interiors》2006,158(1):75-83

The aim of this study is the design and trial of a novel sparse network beamforming (NB) technique to improve earthquake location. For this purpose bulletin phase arrival time data were processed via the use of complex exponents form and then used in an optimization via grid-search to search for the maximum semblance in hypocenter space. The use of the robust semblance statistic, provides reliable location results. The NB location results for a set of test events were compared to standard iterative ISC location procedure “iscloc” and its prototype the Jeffreys maximum likelihood estimator. For this purpose a data-base of 139 reference ground-truth events was extracted from the catalog of the International Seismological Centre (ISC) (97 GT5 events, assumed earthquakes, and 42 GT0 nuclear tests). The tuned NB procedure has shown excellent location results for events with a “good” ISC location and demonstrated the large epicenter deviations have been decreased in “bad” cases. Further developments of the algorithm would include allowances for 3D earth structure and a priori site-specific information.  相似文献   

Designing a monitoring network for detecting groundwater pollution with stochastic simulation and a cost model     

M. F. P. Bierkens 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(5):335-351

A method is presented to design monitoring networks for detecting groundwater pollution at industrial sites. The goal is to detect the pollution at some distance from the site’s boundary so that it can be cleaned up or hydrologically contained before contaminating groundwater outside the site. It is assumed that pollution may occur anywhere on the site, that transport is by advection only and that no retardation and chemical reactions take place. However, the approach can be easily extended to include designated (and uncertain) source areas, dispersion and reactive transport. The method starts from the premise that it is impossible to detect 100% of all the contaminant plumes with reasonable costs and therefore seeks a balance between the risk of pollution and network density. The design approach takes account of uncertainty in the flow field by simulating realisations of conductivity, groundwater head and associated flow fields, using geostatistical simulation and a groundwater flow model. The realisations are conditioned to conductivity and head observations that may already be present on the site. The result is an ensemble of flow fields that is further analysed using a particle track program. From this the probability of missing a contaminant plume originating anywhere on the terrain can be estimated for a given network. From this probability follows the risk, i.e. the expected costs of an undetected pollution. The total costs of the monitoring strategy are calculated by adding the risk of pollution to the costs of installing and maintaining the monitoring wells and the routinely performed chemical analyses. By repeating this procedure for networks of varying well numbers, the best network is chosen as the one that minimises total cost. The method is illustrated with a simulated example showing the added worth of exploratory wells for characterising hydraulic conductivity of a site.  相似文献   

First-order design of geodetic networks using the simulated annealing method     

J. L. Berné  S. Baselga 《Journal of Geodesy》2004,78(1-2):47-54

The general problem of the optimal design for a geodetic network subject to any extrinsic factors, namely the first-order design problem, can be dealt with as a numeric optimization problem. The classic theory of this problem and the optimization methods are revised. Then the innovative use of the simulated annealing method, which has been successfully applied in other fields, is presented for this classical geodetic problem. This method, belonging to iterative heuristic techniques in operational research, uses a thermodynamical analogy to crystalline networks to offer a solution that converges probabilistically to the global optimum. Basic formulation and some examples are studied.  相似文献   

含水层地下储气库参数优化问题分析     

康永尚  杨帆 《地球科学进展》2004,(Z1)

讨论了灰色物元法在含水层储气库参数优化问题中的应用。天然气地下储气库的建造是一项大型、复杂、具有多目标性的工程项目,包括固定资产投资、钻井、修井、注采气工艺完善、地面建设等,需要上亿元的投资,因此其方案的确定,事关重大,必须在建设前期进行充分的技术和工程论证。地下储气库设计方案的优选需要考虑使用功能、技术性、经济性、安全性、环境影响等诸方面的效果进行综合论证,来确定最优方案。由于确定地下储气库优化设计指标类型的多样性,不相容性,且其量纲也不尽相同,甚至有些指标只能是定性描述的非量化灰数,这就导致地下储气库建造设计方案的优选是属灰色系统问题。利用灰色物元分析法优选储气库参数,可以使储气库的参数设计达到最佳。  相似文献