两值随机序列加权和的收敛性

利用二个比较函数讨论了取值０或１的随机序列｛Ｘｎ，ｎ≥１｝加权和Ｓｎ（ｗ）＝∑ｎｉ＝１ａｉＸｉ（ｗ），（ａｉ∈Ｒ）的收敛性．     

方程div（A（│Du│）Du）＋f（│x│,u）=0奇异Dirchlet问题的正…

主要讨论一类非线性偏微分方程奇异Ｄｉｒｉｃｈｌｅｔ问题ｄｉｖ（Ａ（│Ｄｕ│）Ｄｕ）＋ｆ（│ｘ│，ｕ）＝０，ｘ∈Ｒ＾ｎ／｛０｝ｕ（ｒ）〉０，ｒ∈Ｒ＾＋ｌｉｍｕ（ｒ）＝＋∞，ｌｉｍｕ（ｒ）＝０。正径向解的不存在性。     

基于干预ARIMA模型的中国GDP趋势分析

文章通过时间序列分析采用ARIMA模型及干预模型对我国的GDP数据进行分析,引入干预变量,对其进一步建模,拟合出ARIMA(2,2,0)模型。利用干预模型来预测2017年中国GDP的均值。     

岩石节理力学参数的非线性估计

通过建立一个多层神经网络模型ＮＮ（ｎ,ｈ１,ｈ２,１）,探讨了描述节理开度与剪切位移之间的非线性关系和尺度效应的新方法,由小尺度试件节理的实测数据建立的非线性模型可以推广地预测出较大一些尺度试件的节理开度值。对３７条现场实测的节理进行了分形特征研究,建立了分形维数与ＪＲＣ关系式,该关系式可用于ＪＲＣ值的近似分形预测     

试件尺寸对碱——集料反应膨胀的影响

本文研究不同灰集比（ｃ／ａ）及不同集料粒径条件下试件尺寸对碱－硅反应（ＡＳＲ）和碱－碳酸盐反应（ＡＣＲ）膨胀的影响，试验结果表明，试件尺寸对ＡＳＲ膨胀有较大的影响，但对ＡＣＲ膨胀没有显著的影响，对ＡＳＲ膨胀，集料粒径越大，试件尺寸的影响越显著，此外，本文从传热和传质两方面分析了试件尺寸对ＡＡＲ膨胀的影响，认为集料的活性组份的流失是导致这一影响的重要原因。根据研究结果，分析了ＡＳＴＭＣ２２７方法和中     

用组合模型预测软土地基桩基沉降

结合温州地区某桩基工程实测沉降数据,以多元回归分析模型、时间序列分析模型及GM(1,1)灰色理论模型为组合模型的子模型,经大量数据的演算,探讨了不同组合模型建模方案在对历史数据的拟合及未知数据的预测上的不同特点,总结了各种组合模型的一般规律及其适用性.     

警惕混凝土桥梁中AAR的破坏

警惕混凝土桥梁中ＡＡＲ的破坏孙剑陈志源孙家瑛（上海同济大学５０＃）１前言碱—集料反应（ＡＡＲ）是指在混凝土建筑中，由于水泥基体或环境中的碱与某些集料发生化学反应，引起混凝土膨胀、开裂甚至破坏。自１９４０年美国的Ｔ．Ｅ．Ｓｔａｎｔｏｎ首次证实了因为ＡＡ...     

P（nBA＋AA）／P（St＋AN）乳胶IPN的聚合条件及性能研究

本文研究了Ｐ（ｎＢＡ＋ＡＡ）／Ｐ（Ｓｔ＋ＡＮ）乳胶ＩＰＮ的聚合条件，乳化剂，组成对涂膜力学性能的影响和组成，交联剂与成膜性的关系。     

老混凝土工程碱集料反应防治方法研究

本文从物理约束、表面隔水和碱转移三方面研究了老混凝土工程碱集料反应（ＡＡＲ）的防治措施。研究表明，对含ＡＡＲ的混凝土棱柱体施加预压应力可减小ＡＡＲ裂纹；采用有机硅和甲基丙烯酸甲酯对混凝土表层与表面进行适当处理，可在一定程度上抑制ＡＡＲ；一定浓度的ＬｉＯＨ溶液可有效地抑制ＡＡＲ；硅溶胶也能降低ＡＡＲ膨胀，缓和ＡＡＲ破坏。     

Banach函数空间的范数Hlder不等式

本文给出了基本不等式ｎ１ａｉαｉ≤ｎ１αｉａｉ（ａｉ＞０,αｉ＞０,ｎ１αｉ＝１）的一个确界形式,以此统一得出Ｂａｎａｃｈ函数空间ＬＰ（Ｅ,μ）,Ｌ∞（Ｅ,μ）,Ｌ∞（Ｒ）,Ｃ（Ｒ）等的Ｈｏｌｄｅｒ范数不等式     

Verhulst反函数模型滑坡起始预测时刻的选择

 Verhulst反函数模型用于滑坡预测的关键在于起始预测时刻t0的选择。针对用定量计算方法选择t0,研究模型中对数函数自变量存在出现负值的问题。计算所有t0满足模型要求的累计位移和相对位移预测数据,形成预测曲线,通过分析预测曲线与实际监测曲线选择起始预测时刻t0值,得出其选择的主要原则：(1) 预测位移在观测序列点n和n +1处成立;(2) 预测累计位移曲线与实测曲线形态相似;(3) 预测相对位移与实测相对位移在点n处差值最小。多种已知滑坡试验表明：其临滑时刻的预测精度可以达到1个时间间隔以内,t0选择方法是有效的。     

Displacement measurement techniques and numerical verification in 3D geomechanical model tests of an underground cavern group

In this paper, the stability of an underground cavern group is investigated on the basis of large-scale 3D geomechanical model tests and numerical simulations. Multiple measurement techniques are developed to measure the convergence of deformation in the cavern, displacements at key points in the side walls and the damage pattern during the excavation simulation process. The digital photogrammetric technique and fiber Bragg grating (FBG) based displacement sensing bars are applied to measure displacements in the surrounding rock masses. Mini multi-point extensometers with high-precision grating scales are developed as transducers for displacement monitoring. Afterward, a nodal-based Discontinuous Deformation Analysis (NDDA) method is applied to simulate the whole process of the physical model tests and to compare with experimental results. The variation process and law curves of the displacements in the surrounding rock and at key points in the side walls are obtained at excavation stages. The study shows that the application of the displacement measurement methods used in the surrounding rock masses for large-scale model tests of cavern group under true 3-D stress state have achieved satisfactory results.     

边坡非线性位移的神经网络-时间序列分析

边坡的变形表现出复杂的非线性演化特征，大量的工程实践表明利用部分实测的边坡位移时间序列来预测未来边坡的位移更为准确。以神经网络和时间序列分析方法为基础，使用零均值化和标准偏差预处理方法，以及规则化能量函数法和贝叶斯规则化方法进行BP神经网络建模，利用BP网络对边坡位移非平稳时序进行趋势项提取，使非平稳监测时序转化为平稳时序以进行常规ARMA时序分析。结合滚动预测方法，建立了适合岩土体位移预测的神经网络-时间序列分析联合模型，以隔河岩水电站进水口边坡变形和水布垭水电站大岩淌滑坡位移为例进行预测分析。研究结果表明：新模型的预测精度高、实时可靠，可应用于实际工程。     

基于遗传–组合核函数高斯过程回归算法的边坡非线性变形时序分析智能模型

 与支持向量机相比,高斯过程有着容易实现、灵活的非参数推断及预测输出具有概率意义等优点。将高斯过程回归引入边坡非线性变形时序分析,采用单一核函数之和作为高斯过程回归的组合核函数以提高其泛化性能。目前通常采用共轭梯度法求取训练样本对数似然函数的极大值以自适应地获得最优超参数,但共轭梯度法存在优化效果初值依赖性强、迭代次数难以确定、易陷入局部最优解的缺陷。改用十进制遗传算法在训练过程中搜索最优超参数,形成遗传–组合核函数高斯过程回归算法,并编制了相应的计算程序。卧龙寺新滑坡变形时序分析结果表明,与遗传–单一核函数高斯过程回归算法和遗传–支持向量回归算法相比,所提出的遗传–组合核函数高斯过程回归算法显著提高预测精度,可以应用于边坡变形的时序分析,并为类似工程提供借鉴。     

深埋隧道开挖过程动态及破裂形态分析

 地下工程开挖过程中,在洞室围岩中会产生拉压交替变化区,当地应力过大时,会产生分区破裂化现象。为了解释洞室围岩拉压交替变化和分区破裂化现象,根据隧道开挖卸荷这一动力学特征,建立隧道开挖过程的动态分析力学模型和计算模式,由此导出由开挖卸荷引起的扰动应力、扰动应变和扰动位移满足的平衡方程、物理方程、几何方程和边界条件。根据实际的位移约束条件,假设位移试函数,利用Hamilton时域变分原理,考虑时域变分条件和约束变分条件导出围岩体的积分–变分方程组,建立该方程组的模态矩阵。在给定开挖卸荷路径和零初始条件下采用Duhamel积分,得到离散振动方程组的稳态响应。通过矩阵变换,得到隧道围岩体扰动应力、应变和位移的解答函数式。算例分析表明,所给出的理论和方法能正确地反应出隧道开挖引起围岩内的动态过程,并能有效地对开挖引起的围岩的破坏形态进行评价。     

边坡位移时间序列分析预测

将边坡位移看成是一系列时刻t1,t2,t3,…,tn得到的时间序列,采用时间序列AR模型,对其进行模型识别、参数估计、位移预报。预测结果表明：AR模型实时建模的分析方法能较好地反映边坡位移变形的动态变化规律,准确预报出边坡位移的发展趋势。     

Deformation and failure mechanism of slope in three dimensions

Understanding three-dimensional(3D)slope deformation and failure mechanism and corresponding stability analyses are crucially important issues in geotechnical engineering.In this paper,the mechanisms of progressive failure with thrust-type and pull-type landslides are described in detail.It is considered that the post-failure stress state and the pre-peak stress state may occur at different regions of a landslide body with deformation development,and a critical stress state element(or the soil slice block)exists between the post-failure stress state and the pre-peak stress state regions.In this regard,two sorts of failure modes are suggested for the thrust-type and three sorts for pull-type landslides,based on the characteristics of shear stress and strain(or tensile stress and strain).Accordingly,a new joint constitutive model(JCM)is proposed based on the current stability analytical theories,and it can be used to describe the mechanical behaviors of geo-materials with softening properties.Five methods,i.e.CSRM(comprehensive sliding resistance method),MTM(main thrust method),CDM(comprehensive displacement method),SDM(surplus displacement method),and MPM(main pull method),for slope stability calculation are proposed.The S-shaped curve of monitored displacement vs.time is presented for different points on the sliding surface during progressive failure process of landslide,and the relationship between the displacement of different points on the sliding surface and height of landslide body is regarded as the parabolic curve.The comparisons between the predicted and observed load e displacement and displacement e time relations of the points on the sliding surface are conducted.The classi fi cation of stable/unstable displacement e time curves is proposed.The de fi nition of the main sliding direction of a landslide is also suggested in such a way that the failure body of landslide(simpli fi ed as"collapse body")is only involved in the main sliding direction,and the strike and the dip are the same as the collapse body.The rake angle is taken as the direction of the sum of sliding forces or the sum of displacements in collapse body,in which the main slip direction is dependent on progressive deformation.The reason of non-convergence with fi nite element method(FEM)in calculating the stability of slope is also numerically analyzed,in which a new method considering the slip surface associated with the boundary condition is proposed.It is known that the boundary condition of sliding surface can be described by perfect elasto-plastic model(PEPM)and JCM,and that the stress and strain of a landslide can be described properly with the JCM.     

Optimal shakedown design of metal structures under stiffness and stability constraints

Optimal shakedown design of metal frame and truss-like structures is considered in this paper. Strength, stiffness and stability (only for trusses) constraints are included in non-linear mathematical models of volume minimization problems of structures. Stiffness conditions are realized by the restriction of structure deflections or nodal displacements, which can vary non-monotonically during the adaptation process. Determination of displacements is especially complicated if the variable repeated load is defined by variation bounds, which are not related to time. For trusses, stability constraints are related to recommendations of Eurocode 3 (EC3). Numerical examples concerning the calculation of frame and truss structures are presented. The results are valid for the small displacement assumptions.     

Analytical model for evaluating XCC pile shaft capacity in soft soil by incorporating penetration effects

The derivation of a new analytical model for predicting the soil displacement of X-section cast-in-place concrete (XCC) piles installed vertically into soft clay as well as for predicting limit shaft resistance during loading phases is presented in this paper. The analytical model is formulated by assuming that the XCC pile penetration process is an X-shaped cylindrical cavity expansion process. Based on the theoretical framework of the Strain Path Method (SPM), the strain, displacement and stress induced by X-shaped cavity expansion can be obtained. The proposed analytical model is validated by comparing the degenerate solution of this study with that of conventional circular (cylindrical) cavity expansion theory. Analytical model-based design methods are then proposed for evaluating soil displacement and XCC pile shaft capacity. Theoretical predictions are compared with field test measurements to verify the suitability of the proposed design method. The proposed new analytical model reveals the fundamental penetration mechanics of XCC piles and gives improved design methods for determining XCC pile shaft capacities.     

空间结构变更后的有限元分析法

基于有限元分析,本提出空间结构变更后的新算法。该算法将杆件撤除这高为原结构上施加了关联荷载,不需重建并分解总刚,重新求解方程组,大大减小计算量。中导出求关联荷载的一般算式。