某一特定场地的岩土力学参数在地质作用下普遍呈现固有的不确定性,融合现场观测数据进行概率反分析可有效缩减这一不确定性。虽然基于子集模拟的贝叶斯更新(Bayesian Updating with Subset simulation,简称BUS)方法可以将等量场地信息...某一特定场地的岩土力学参数在地质作用下普遍呈现固有的不确定性,融合现场观测数据进行概率反分析可有效缩减这一不确定性。虽然基于子集模拟的贝叶斯更新(Bayesian Updating with Subset simulation,简称BUS)方法可以将等量场地信息的高维概率反分析问题转化为等效的结构可靠度问题,但是当现场观测数据增多时,构建的似然函数值会变得非常小,甚至低于计算机浮点运算精度,会严重影响概率反分析计算效率与精度。为此,提出了一种基于并联系统可靠度分析的改进BUS方法,从基于乔列斯基分解的中点法出发,将接受率低的总失效区域分解为多个接受率高的子失效区域,从而避免因融合大量现场观测数据引起的“维度灾难”问题,实现对边坡岩土力学参数的准确概率反分析。最后,通过一不排水饱和黏土边坡案例验证了提出方法的有效性,结果表明提出的方法能够融合大量钻孔数据和边坡服役状态等观测信息高效进行岩土力学参数概率反分析及边坡可靠度评估,为高维空间变异参数概率反分析和边坡可靠度评估提供了一种有效的工具。展开更多
基坑开挖工程中,最大地表沉降和最大墙体侧移是非常重要的两个变形量。然而由于土体存在变异性,基坑开挖变形难以准确预测。提出一种基于KJHH模型的基坑开挖概率反分析方法,可以同时预测最大地表沉降和最大墙体侧移。在贝叶斯更新框架下...基坑开挖工程中,最大地表沉降和最大墙体侧移是非常重要的两个变形量。然而由于土体存在变异性,基坑开挖变形难以准确预测。提出一种基于KJHH模型的基坑开挖概率反分析方法,可以同时预测最大地表沉降和最大墙体侧移。在贝叶斯更新框架下,动态融合各开挖阶段观测数据,利用多重数据同化集合平滑器(Ensemble smoother with multiple data assimilation, ES-MDA)更新土体参数,提高变形预测准确性。以台北TNEC基坑工程为例,验证了所提方法的有效性。实验结果表明:随着融合更多不同开挖阶段的观测数据,预测均值和实测值趋于一致;对于TNEC工程,假设先验分布服从对数正态分布得到的开挖变形预测结果略大于采用均匀分布时的预测结果;变形预测的准确性随着迭代次数和样本量的增加而提高。展开更多
Offshore project risk concerns many influence factors with complex relationship, and traditional methods cannot be used for the evaluation on risk probability. To deal with this problem, a new method was developed by ...Offshore project risk concerns many influence factors with complex relationship, and traditional methods cannot be used for the evaluation on risk probability. To deal with this problem, a new method was developed by the combination of improved technique for order preference by similarity ideal solution method, analytical hierarchy process method and the network response surface method. The risk probability was calculated by adopting network response surface analysis based on the state variable of a known event and its degree of membership.This quantification method was applied to an offshore platform project, Bonan oil and gas field project in Bohai Bay in June 2004.There were 7 sub-projects and each includes 4 risk factors.The values of 28 risk factors, ranging from 10^-6 to 10^-4, were achieved. This precision conforms to the international principle of as low as reasonably practically.The evaluation indicates that the values of comprehensive level of construction group and ability of technical personnel on the spot are relatively high among all risk factors, so these two factors should be paid more attention to in offshore platform construction.展开更多
The mechanism of the leaching process of chalcopyrite concentrate with sodium nitrate in sulphuric acid solution were studied and discussed. Chemical reactions of leaching and their thermodynamic probabilities are pre...The mechanism of the leaching process of chalcopyrite concentrate with sodium nitrate in sulphuric acid solution were studied and discussed. Chemical reactions of leaching and their thermodynamic probabilities are predicted based on the calculated Gibbs energies and analysis of E-pH diagrams. Experimental data, thermodynamic analysis, chemical, XRD, and SEM/EDX analyses of concentrate and the leach residues, were performed to develop a better understanding of the chemical reactions that took place in the system. Elemental sulphur was formed as the main leaching product, precipitated at the particle surfaces and tended to inhibit the leaching rate.展开更多
文摘某一特定场地的岩土力学参数在地质作用下普遍呈现固有的不确定性,融合现场观测数据进行概率反分析可有效缩减这一不确定性。虽然基于子集模拟的贝叶斯更新(Bayesian Updating with Subset simulation,简称BUS)方法可以将等量场地信息的高维概率反分析问题转化为等效的结构可靠度问题,但是当现场观测数据增多时,构建的似然函数值会变得非常小,甚至低于计算机浮点运算精度,会严重影响概率反分析计算效率与精度。为此,提出了一种基于并联系统可靠度分析的改进BUS方法,从基于乔列斯基分解的中点法出发,将接受率低的总失效区域分解为多个接受率高的子失效区域,从而避免因融合大量现场观测数据引起的“维度灾难”问题,实现对边坡岩土力学参数的准确概率反分析。最后,通过一不排水饱和黏土边坡案例验证了提出方法的有效性,结果表明提出的方法能够融合大量钻孔数据和边坡服役状态等观测信息高效进行岩土力学参数概率反分析及边坡可靠度评估,为高维空间变异参数概率反分析和边坡可靠度评估提供了一种有效的工具。
文摘基坑开挖工程中,最大地表沉降和最大墙体侧移是非常重要的两个变形量。然而由于土体存在变异性,基坑开挖变形难以准确预测。提出一种基于KJHH模型的基坑开挖概率反分析方法,可以同时预测最大地表沉降和最大墙体侧移。在贝叶斯更新框架下,动态融合各开挖阶段观测数据,利用多重数据同化集合平滑器(Ensemble smoother with multiple data assimilation, ES-MDA)更新土体参数,提高变形预测准确性。以台北TNEC基坑工程为例,验证了所提方法的有效性。实验结果表明:随着融合更多不同开挖阶段的观测数据,预测均值和实测值趋于一致;对于TNEC工程,假设先验分布服从对数正态分布得到的开挖变形预测结果略大于采用均匀分布时的预测结果;变形预测的准确性随着迭代次数和样本量的增加而提高。
文摘Offshore project risk concerns many influence factors with complex relationship, and traditional methods cannot be used for the evaluation on risk probability. To deal with this problem, a new method was developed by the combination of improved technique for order preference by similarity ideal solution method, analytical hierarchy process method and the network response surface method. The risk probability was calculated by adopting network response surface analysis based on the state variable of a known event and its degree of membership.This quantification method was applied to an offshore platform project, Bonan oil and gas field project in Bohai Bay in June 2004.There were 7 sub-projects and each includes 4 risk factors.The values of 28 risk factors, ranging from 10^-6 to 10^-4, were achieved. This precision conforms to the international principle of as low as reasonably practically.The evaluation indicates that the values of comprehensive level of construction group and ability of technical personnel on the spot are relatively high among all risk factors, so these two factors should be paid more attention to in offshore platform construction.
文摘The mechanism of the leaching process of chalcopyrite concentrate with sodium nitrate in sulphuric acid solution were studied and discussed. Chemical reactions of leaching and their thermodynamic probabilities are predicted based on the calculated Gibbs energies and analysis of E-pH diagrams. Experimental data, thermodynamic analysis, chemical, XRD, and SEM/EDX analyses of concentrate and the leach residues, were performed to develop a better understanding of the chemical reactions that took place in the system. Elemental sulphur was formed as the main leaching product, precipitated at the particle surfaces and tended to inhibit the leaching rate.
