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集对分析对边坡稳定性进行评价时,采用线性公式来表达联系度,难以准确反映工程实际,且具体的联系度扼杀了系统的随机性。对此,将云理论中“隶属云”的概念引入对联系度进行改进得到云联系度,形成了集对云模型。该模型将云联系度矩阵与云理论改进AHP确定的权重矩阵相结合,得到综合云联系度矩阵,通过云发生器绘出等级云图。该模型兼顾系统的模糊性和随机性,且实现了等级的可视化,并通过X云发生器得到隶属不同等级的概率。将该模型应用于边坡工程中,与既有模型和工程实际进行对比分析,验证该模型的准确性,并对不同的边坡进行稳定性排序。模型结合云理论与集对分析的优点,充分考虑系统的随机性,为边坡稳定性评价提供了一种思路和参考。 相似文献
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优势断裂找寻是区域稳定性评价的重要内容,关系到重大工程的安全运行和场址选择.本文基于粗糙集和集对分析理论,探讨了优势断裂的粗糙集对势评价模型,即首先据优势面理论确定了分析优势断裂的优势指标,应用粗糙集理论对待评断裂的评价指标进行约简,并基于属性重要性计算相应约简后指标的权重,通过集对分析理论计算待评样本与指标最优、最劣值的集对同一度和对立度及集对同势,进而提出相应的优势断裂集对同势判定标准,以确定工程区域优势断裂.实例应用和与其它方法对比分析结果表明,该模型应用于区域优势断裂评价是有效可行的且客观;规模优势指标、距离优势指标和时间优势指标对润扬大桥桥址区断裂活动性影响相对大,茅山断裂、郯庐断裂和长江断裂为工程区域优势断裂. 相似文献
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为弥补当前水资源空间均衡评估中对指标模糊性和信息动态性考虑不足的缺陷,基于可变集原理及偏联系数方法构建一种新的水资源空间均衡评估模型。采用可变集方法计算评价对象的相对隶属度,获取级别特征值;利用偏联系数方法探究信息演化对级别的影响,得到基于支持度最大原则的定级策略;综合二者结果对水资源空间均衡状况进行评估。将模型应用于2017年中国31个省级行政区的结果表明:①中国东南地区水资源空间均衡程度良好,西北地区较差,南方优于北方、东部优于西部;②北京市等17个省级行政区的水资源空间均衡状态呈现不同程度的负向演化态势,亟待进一步加强管理,其余地区呈现良性的发展态势;③四川等省份各指标的均衡程度差异较大,需针对性地进行调控与优化。 相似文献
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隧道水害危险性评价是一个非线性复杂的不确定系统问题。首先,针对其评价指标参数具有不确定性、模糊性和随机性等特点,在充分考虑岩溶隧道水害危险性评价指标关联性的基础上,提出了基于Jousselme距离的指标信度测度动态赋权理论,实现不同的实例、不同的指标实测值对整个系统的动态赋权,降低实际工作中由于指标实测值误差或错误导致评价结果偏差的风险;其次,运用云理论优化集对联系度,与所得权重加权得出系统综合云联系度,并与等级评价区间期望加权平均得到危险值,同时生成对应的等级云图判定隧道水害危险性等级,进而判定岩溶隧道水害危险状态,实现水害危险等级判定的可视化;再次,基于大气降水为岩溶隧道水害主要来源的视角,选取年均降水量、入渗系数、汇水面积、渗透系数和单位涌水量5项指标作为集对云评价指标,并以6条典型岩溶隧道为样本数据进行模型检验,发现评价结果与其他方法的评价结果相吻合,证明了该模型的可靠性和有效性。最后,将模型应用于京珠高速公路媲双坳岩溶隧道水害事故中,评价结果与实际情况相符,采取与评价等级相对应的处治措施,取得了良好的水害治理效果,表明该模型具有工程实用价值,评价流程可操作性强,为岩溶隧道水害的预测和防治提供参考。 相似文献
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A novel application of multi-criteria decision making (MCDM) technique to seismic soil liquefaction, a complex problem in earthquake geotechnical engineering, is presented. Seismic soil liquefaction depends on a diversified set of physical parameters with highly non-linear interconnections. Factors governing liquefaction may broadly be grouped as seismic parameters, site conditions and primarily dynamic soil properties, as the stimulus itself is manifestly dynamic. Each of these factors incorporates a wide range of variety of parameters that characterize liquefaction, to a varying degree of significance, such as: the magnitude, effective overburden pressure, shear modulus, normalized standard penetration blow count [N1]60, etc. Estimating rapid, yet accurate and reliable liquefaction susceptibility requires identification of the most significant factors controlling liquefaction. Thus a new concept of extracting significant parameters and gauging their importance is carried out by assigning them weights by applying MCDM introduced herein, whose evaluation is accomplished by means of an ‘entropy method’. In line with this, a relative reliability risk index (R3I) is computed indicating the ranking that directly reflects the severity of risk for liquefaction. Although the entropy analysis is carried out separately for the three multivariate criteria, it is remarkable that the R3I evaluated for each of these gives consistent ranking. 相似文献
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由于边坡支护方案评价时掌握的信息不充分,资料不全,加之问题本身的复杂性、不确定性以及人类思维的模糊性,方案的评价值往往难以精确表达,用三角模糊数的形式表示更合理。针对属性值用三角模糊数表示的边坡支护方案优选问题,提出了一种基于集对分析联系数的三角模糊数型方案综合评价模型。首先,根据集对分析中的联系数理论,利用三角模糊数的中值及上下确界所限定的取值区间,将三角模糊数转化为联系数;然后,根据联系数的加法和乘法定义,建立了联系数决策模型;按照综合决策值大小即可得到最优方案。该模型既考虑了三角模糊数的中值,又兼顾了三角模糊数的上下确界,即联系数的差异度,更具有客观性、合理性。实例应用表明,该模型算理清晰,计算简便,结论与实际相符。 相似文献
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文摘将可拓工程方法与工程地质评价结合,在物元理论、可拓集合理论和关联函数运算的基础上进行关联度的计算,建立了工程地质评价的物元模型。运用此物元模型进行临港新城规划区的砂土液化评价,证明可拓学理论在工程地质多因素综合评价中的应用是可行的,并且具有定量与定性相结合、因地制宜的考虑所选取的因素等优势。 相似文献
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This article describes a new performance-based approach for evaluating the return period of seismic soil liquefaction based on standard penetration test (SPT) and cone penetration test (CPT) data. The conventional liquefaction evaluation methods consider a single acceleration level and magnitude and these approaches fail to take into account the uncertainty in earthquake loading. The seismic hazard analysis based on the probabilistic method clearly shows that a particular acceleration value is being contributed by different magnitudes with varying probability. In the new method presented in this article, the entire range of ground shaking and the entire range of earthquake magnitude are considered and the liquefaction return period is evaluated based on the SPT and CPT data. This article explains the performance-based methodology for the liquefaction analysis – starting from probabilistic seismic hazard analysis (PSHA) for the evaluation of seismic hazard and the performance-based method to evaluate the liquefaction return period. A case study has been done for Bangalore, India, based on SPT data and converted CPT values. The comparison of results obtained from both the methods have been presented. In an area of 220 km2 in Bangalore city, the site class was assessed based on large number of borehole data and 58 Multi-channel analysis of surface wave survey. Using the site class and peak acceleration at rock depth from PSHA, the peak ground acceleration at the ground surface was estimated using probabilistic approach. The liquefaction analysis was done based on 450 borehole data obtained in the study area. The results of CPT match well with the results obtained from similar analysis with SPT data. 相似文献
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基于模糊因素的岩质边坡地震稳定性多模型组合评价 总被引：2，自引：0，他引：2
岩质边坡地震稳定性评价是岩土边坡地震失稳防治的基础工作,针对评价过程中评价因素的多源模糊性,借鉴工程可变模糊集理论,将模糊可变评价模型应用于岩质边坡地震稳定性评价中。综合考虑岩质边坡内在结构和外部自然条件,选取岩土体特性、新构造运动特征、坡高、坡角、年均降雨量和场地地震烈度6个指标作为评价指标体系并建立等级标准;将改进熵权算法引入该模型中,利用指标实际数据离散性求权重;通过改变模糊可变评价模型参数对岩质边坡地震稳定性进行线性与非线性组合评价,并将均值作为最终评价结果。将该方法应用于天然边坡与路堑边坡实例中,结果表明,模糊可变评价模型评价结果合理、客观,具有更高的可靠性与稳定性,为岩质边坡地震稳定性评价工作提供了一种新的研究方法与思路 相似文献
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与圆颗粒的标准砂相比较,片状结构的砂的动力特性更为复杂,用规范法进行液化判别时会误判。为了将砂土片状结构特性考虑到判别过程中,建议了一个更为合理的Ncr 的经验公式,并利用该公式对南京地铁玄武门-南京站区间的砂土层进行液化判别,该区间会发生中等程度为主的液化,最后,将液化判别结果与规范法和室内动力实验结果相比较,分析发现,在南京地铁进行液化判别时,必须考虑片状结构特性对于液化影响;同时,给出了平均液化势随深度的变化情况,以及考虑砂土结构特性对判别结果的影响系数随土层深度的关系,提高了判别的精度。 相似文献
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选择平顶山煤田二矿、十矿和十二矿51个钻孔的隔水层厚度、断层复杂程度、含水层水压、含水层单位涌水量、采高5个因素为评价因子,以层次分析法和灰色关联分析法计算的常权权重为基础,应用变权理论确定各指标因子的变权权重;分别利用物元可拓法、模糊可变集理论、突变理论、模糊综合评价法,对煤层底板突水危险性进行评价并确定突水危险性等级。与实际开采情况的对比分析证明,模糊可变集理论是最适宜研究区的底板突水危险性评价方法,评价结果与开采实际较为吻合。模糊可变集理论的评价表明,二矿、十矿、十二矿带压区内安全区占比分别为4.08%、14.30%、0,低威胁区占比分别为76.91%、83.14%、85.78%,高威胁区占比分别为19.01%、2.56%、14.22%,研究区内暂无危险区。 相似文献
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The performance-based liquefaction potential analysis was carried out in the present study to estimate the liquefaction return
period for Bangalore, India, through a probabilistic approach. In this approach, the entire range of peak ground acceleration
(PGA) and earthquake magnitudes was used in the evaluation of liquefaction return period. The seismic hazard analysis for
the study area was done using probabilistic approach to evaluate the peak horizontal acceleration at bed rock level. Based
on the results of the multichannel analysis of surface wave, it was found that the study area belonged to site class D. The
PGA values for the study area were evaluated for site class D by considering the local site effects. The soil resistance for
the study area was characterized using the standard penetration test (SPT) values obtained from 450 boreholes. These SPT data
along with the PGA values obtained from the probabilistic seismic hazard analysis were used to evaluate the liquefaction return
period for the study area. The contour plot showing the spatial variation of factor of safety against liquefaction and the
corrected SPT values required for preventing liquefaction for a return period of 475 years at depths of 3 and 6 m are presented
in this paper. The entire process of liquefaction potential evaluation, starting from collection of earthquake data, identifying
the seismic sources, evaluation of seismic hazard and the assessment of liquefaction return period were carried out, and the
entire analysis was done based on the probabilistic approach. 相似文献
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This papers presents a new approach for developing a limit state for liquefaction evaluation based on field performance data. As an example to illustrate the new approach, a database that consists of, among many other features, in situ shear wave velocity measurements and field observations of liquefaction/non‐liquefaction in historic earthquakes is analysed. This database is first used to train a neural network to classify liquefaction/non‐liquefaction based on soil resistance parameters and load parameters. The successfully trained and tested neural network is then used to establish a limit state, a multiple dimension boundary that separates ‘zone’ of liquefaction from ‘zone’ of non‐liquefaction. The limit state yields cyclic resistance ratio for a given set of soil resistance parameters. Examination of all cases in the database show that the developed limit state has a high degree of accuracy in predicting the occurrence of liquefaction/non‐liquefaction. The developed neural network model can accurately predict the cyclic resistance ratio of soils. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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基于模糊数学理论,通过统计经验数据,采用熵值法对影响近松散含水层安全开采的关键因素赋权,利用GIS定量确定各个因素的隶属度,构造了基于熵值的模糊综合评判模型。以山东某矿六采区01工作面开采为例,选择覆岩厚度、断层构造、第四系底部粘土层厚度、底部含水层的单位涌水量、煤层开采厚度、导水裂隙带高度6个影响因素为评判指标,确定了可行性程度的评判集:{较低,低,中等,高,很高},依据水体下开采的有关安全规程,采用GIS方法确定了各个因素的隶属度,并利用历史开采经验数据确定各个影响因素的权重。对该工作面近松散含水层下开采的评判结果表明,该工作面控制采高为2 m时开采是安全可行的,开采过程中针对薄弱环节采取了相应措施,没有发生突水溃砂事件,初步验证了该模糊综合评判模型的实用性。 相似文献
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A review of probabilistic and deterministic liquefaction evaluation procedures reveals that there is a need for a comprehensive approach that accounts for different sources of uncertainty in liquefaction evaluations. For the same set of input parameters, different models provide different factors of safety and/or probabilities of liquefaction. To account for the different uncertainties, including both the model and measurement uncertainties, reliability analysis is necessary. This paper presents a review and comparative study of such reliability approaches that can be used to obtain the probability of liquefaction and the corresponding factor of safety. Using a simplified deterministic Seed method, this reliability analysis has been performed. The probability of liquefaction along with the corresponding factor of safety have been determined based on a first order second moment (FOSM) method, an advanced FOSM (Hasofer–Lind) reliability method, a point estimation method (PEM) and a Monte Carlo simulation (MCS) method. A combined method that uses both FOSM and PEM is presented and found to be simple and reliable for liquefaction analysis. Based on the FOSM reliability approach, the minimum safety factor value to be adopted for soil liquefaction analysis (depending on the variability of soil resistance, shear stress parameters and acceptable risk) has been studied and a new design safety factor based on a reliability approach is proposed. 相似文献