基于无监督方法确定岩土参数取值

随着城市工程建设的发展,建筑工程事故问题愈发突出,采用传统方法求取的岩土参数区间无法满足实际工程需要。基于无监督学习思想,选取工程性质较差的泥炭质土,结合工程经验选用8个物理指标作为输入集,利用主成分分析（priciple components analysis, PCA）算法实现多样本多参数去耦合的降维处理,得出各物理指标相关性及敏感度,结合其相关性及敏感度赋予不同埋深泥炭质土物理指标的综合评价值。利用k-means聚类分析泥炭质土物理指标、综合评价值及工程特性之间的关系,为岩土参数选取提供理论基础。采用监督学习方法——BP神经网络算法分析无监督结果,验证（PCA—k-means）算法模型的合理性。将通过聚类分析得到的正态样本利用多种截尾法优化,得到可靠取值区间,并将取值结果与实际工程取值比较,验证了该模型工程参数取值的合理性。该算法模型具有较好的工程应用价值,所得研究结果可为工程勘察、设计、施工参数取值提供参考,也能为岩土参数取值分析提供新的分析方法。     

基于层次分析法的矿山岩土工程系统环境质量多目标评价模型

矿山开发给矿区环境带来了负面影响,对矿山环境质量进行评价是实现矿业可持续发展的必要手段。笔者建立了矿山岩土工程环境质量多目标评价指标体系,运用层次分析法确定出各个评价指标的权重; 规定了分级规则,并对各个评价指标进行了分级; 建立了矿山岩土工程体系环境质量多目标综合评价模型,并将该模型应用于矿山实际,得出该矿山环境质量较差,需及时采取措施进行治理。     

基于神经网络的采空塌陷预测

依据某煤炭开采区的勘察资料, 综合考虑影响采空塌陷的主要因素, 建立了预测采空塌陷的 BP神经网络模型。该模型结构为 7-10-2型。优化学习参数后, 用该模型对采空区塌陷进行了预测分析, 结果与实际情况完全吻合, 表明 BP神经网络模型应用于采空塌陷预测领域是行之有效的。     

岩土工程中的设计地震动参数确定

与岩土工程相关的设计地震动参数的规定分散在各行业的工程设计规范之中,比较了主要技术规范中设计地震动参数规定之间的差别,讨论了在岩土工程的勘察与设计中确定地震动参数的方法和内容,分析和研究了确定设计地震动参数时不同规范之间需要协调的主要问题,指出了在目前岩土工程中的设计地震动参数确定方面的需要重点关注的参数选择的合理性,提出了具有地震工程专业基础（注册地震安评工程师）的注册土木工程师（岩土）确定具体设计地震动参数应更符合工程建设的实际需要的建议。     

Rock slopes risk assessment based on advanced geostructural survey techniques

The rock mass structure determines the possible unstable blocks that can induce rock fall phenomena. The stability analyses must therefore be based on an accurate geo-structural survey. In this work, the stability conditions of several steep slopes along a motorway in the Far East have been evaluated through key block analysis based on traditional surveys and on laser scanner acquisitions. Discontinuity orientations and positions on the rock face are derived from the point cloud in order to perform the reconstruction of the rock mass and to identify blocks in the slope. Results obtained from both the traditional and the new method is in good agreement. Stability analyses have been performed for evaluating the kinematic feasibility of different failure mechanisms. The rock block shapes and volumes are computed by performing 2D and 3D analyses whereas the failure mechanisms are examined using the key block method. Parametrical analyses have been carried on to evaluate the influence of slope angle variation. DEM models have also been set up. The relative hazard is determined by statistically evaluating the kinematical feasibility of different failure mechanisms. Hazard mapping has been utilized to identify the best methodology for risk mitigation.     

某些岩土参数的对数正态分布特征

本文试图说明服从对数正态分布岩土参数频率直方图的分布特征和在累积频率概率格纸上作正态检验及求取参数特征值的统计方法。使岩土参数的统计更合理     

Multiple-point geostatistical modeling based on the cross-correlation functions

An important issue in reservoir modeling is accurate generation of complex structures. The problem is difficult because the connectivity of the flow paths must be preserved. Multiple-point geostatistics is one of the most effective methods that can model the spatial patterns of geological structures, which is based on an informative geological training image that contains the variability, connectivity, and structural properties of a reservoir. Several pixel- and pattern-based methods have been developed in the past. In particular, pattern-based algorithms have become popular due to their ability for honoring the connectivity and geological features of a reservoir. But a shortcoming of such methods is that they require a massive data base, which make them highly memory- and CPU-intensive. In this paper, we propose a novel methodology for which there is no need to construct pattern data base and small data event. A new function for the similarity of the generated pattern and the training image, based on a cross-correlation (CC) function, is proposed that can be used with both categorical and continuous training images. We combine the CC function with an overlap strategy and a new approach, adaptive recursive template splitting along a raster path, in order to develop an algorithm, which we call cross-correlation simulation (CCSIM), for generation of the realizations of a reservoir with accurate conditioning and continuity. The performance of CCSIM is tested for a variety of training images. The results, when compared with those of the previous methods, indicate significant improvement in the CPU and memory requirements.     

基于RS与LS-SVR的储层参数预测

该文提出结合粗糙集（RS）和最小二乘支持向量回归（LS-SVR）的方法。该方法利用RS对原始数据进行约简，更好地减少了支持向量的维数；同时采用LS-SVR解决了常规SVM计算速度幔、抗噪能力差的缺点。实例证明该方法应用在复杂地层储层参数预测中具有优越性。     

Subsidence on steep slopes due to longwall mining

Summary A two dimensional finite element model is used to simulate the extraction of coal by the longwall method underneath idealized surface slopes. The resulting subsidence, tilt and horizontal displacement values are compared with similar extractions using the same method beneath initially horizontal surfaces. The conclusions of a parametric study using this model, supported by field evidence, indicate that in areas of rugged topography, simple application of the procedures outlined in the National Coal BoardSubsidence Engineer's Handbook (1975) does not give acceptable predictions of the induced ground movements.     

相关型岩土参数分析和选用

岩土参数与应力环境、沉积条件、风化程度和埋藏条件等因素相关,其统计值具有空间变异性和相关性,采用非相关型岩土统计参数进行岩土工程设计具有不经济性。通过分析岩土参数的变化规律及与其相关的主要因素,说明岩土参数可用深度或参数与地层顶面或底面的距离作为相关参数进行相关型判别,论述相关型参数的判定标准和相关型标准值的计算方法,采用图解法分析相关型参数多种取值方法的可靠性。以华南某核电厂常规岛地基和某变电站边坡为例,介绍了相关型岩土参数标准值经验公式在岩土设计优化中的应用。分析表明：具有规律性变化的岩土参数宜选择恰当的相关参数划分为相关型,相关参数可取参数与地层顶面或底面的距离,相关型岩土参数标准值可使岩土设计方案更具合理性和经济性。     

Influence of depositional processes on the geotechnical parameters of Chicago glacial clays

The effects of depositional environment on properties, stress history, and undrained and drained shear-strength parameters are evaluated for Chicago glacial clay. Recent geology and basic depositional environments are described. Both laboratory and in-situ shear-strength evaluations have been conducted at several sites in the study area. Results of the investigations indicate that, while depositional environment has a large impact on the engineering properties of these clays, identification of the depositional environment is in itself insufficient to strength parameters. Post-depositional events are shown to alter the stress history imparted during deposition and thus impact shear-strength parameters.     

煤层地下开采地表沉陷预测的边值方法

采空区上覆岩、土体对地表沉陷的耦合行为可归结为弹性理论的边值问题,由不同性状松散表土层确定的应力边界和岩、土体之间形成的位移边界构成了相应边值问题的定解条件。在已有研究成果的基础上,提出了地表下沉预测研究的边值提法,以探讨地下开采引起的地表沉陷规律。给出了采空区上覆表土层内任一点的位移和地表下沉的计算公式,确定了地表沉陷的范围,并以神东矿区大柳塔1203工作面开采引发的地表沉陷为例给出了工程实例。研究结果表明,采空区上覆岩体对地表及表土层内任一点下沉的影响取决于上部岩层破断后的结构形态;采空区上覆土体对地表下沉量的作用与土体性质及表土层厚度有关,土体对表土层下沉的影响由下而上增大,呈非线性变化,至地表达最大值;地表沉陷区域随表土层厚度的增加而增大,其影响范围远大于采空区。     

弱透水层瞬态水力参数的地质统计反演识别研究

弱透水层释水变形伴随着水力参数(渗透系数K和贮水率Ss)的瞬态变化,传统的“移动窗口”式反演方法假定每个反演窗口的初始状态是静态的,这与弱透水层释水变形存在明显滞后效应的实际情况不符。本文提出了在高维参数反演优化情境下,时间域上模型参数的动态变化可与空间域上模型参数的一维非均质性等价,因而可用地质统计反演方法可用于识别弱透水层瞬态K和Ss的新思路,实现了该方法在水文地质领域的创新性应用。以上海越流含水层系统为例,运用似线性地质统计反演算法,高精度地拟合了F16分层标处的长观变形数据,获取了原位透镜体状弱透水层K和Ss的瞬态特征。反演结果显示,观测时段内K的变幅为1. 02×10-5~5. 89×10-4 m/a,平均值为1. 38×10-4 m/a,Ss的变幅为4. 34×10-4~6. 02×10-3 m-1,平均值为2. 65×10-3 m-1。基于反演所得参数瞬态特征,分析原位弱透水层在1994年前后分别以弹性和塑性变形为主,弱透水层K呈现与含水层水位相反的季节性变化特征,该现象可能与渗流力作用下细粒物质在含水层与弱透水层透镜体交界面附近的对孔隙的阻塞和疏通作用有关。该方法可获取完整观测时段内水文地质参数的动态变化轨迹,在计算评价地表水 地下水交互领域的河床渗透性、原位修复领域的渗透反应墙渗透性等的动态演化特征方面具有潜在的应用价值,并可作为构建水文地质领域、岩土工程等领域有关本构模型的有效辅助手段。     

基于动力学和材料软化特性的边坡渐进破坏特征研究

边坡的失稳是一个从量变到质变的动态渐进破坏过程,此问题也是边坡领域研究的重点与难点之一。在考虑岩土材料软化特性和动力学求解的基础上,建立了边坡渐进破坏仿真的理论框架;利用ABAQUS软件的动力显式求解模块实现了边坡的渐进破坏仿真;根据塑性应变揭露了剪切带的扩展过程,由软化本构确定了滑面材料的分区演化规律,根据等效塑性应变确定了边坡的滑面,通过滑面位置将边坡分为滑体、滑带、滑床,并分别研究了边坡各分区内部特征点运动学变量的发展过程,从而揭示了边坡的渐进破坏过程;基于材料参数沿滑面的时空分布,利用矢量和法得到了边坡不同演化阶段的安全系数。对比该方法与Bishop法确定的滑面位置与安全系数,发现两种方法峰值和残余强度对应的安全系数比较接近,该方法搜索所得滑面位于Bishop法自动搜索的滑面之间,验证了此方法的合理性及可靠性。最后分析了材料软化特征对边坡稳定性的影响,在保持其他参数不变的条件下,增大残余黏聚力,边坡的滑面位置加深,安全系数的初始值减小,安全系数的快速减小阶段有所推迟,并且快速减小阶段经历的时间有所延长,稳定后的安全系数有所增大。保持其他参数不变,增大残余黏聚力对应的等效塑性应变阈值,边坡的滑面位置加深,安全系数的初始值减小,安全系数的快速减小阶段有所推迟,但快速减小阶段经历的时间基本不变,达到稳定的时间有所推迟,同时稳定后的安全系数略微有所增大。     

煤炭勘查中岩土参数的统计分析

基于岩土工程勘察规范中岩土参数标准值的确定方法,就修正系数在置信度为0.95和0.90的简化公式进行了讨论,并运用于煤炭勘查项目中具体力学参数的标准值计算。结果表明,工程实际中若遇试验数据不足,置信度0.95和0.90修正系数的简化公式均具有足够的精度;采用服从标准正态分布计算的置信度为0.90的单侧置信下限与采用正态分布计算的置信度为0.95的单侧置信下限相等。     

基于STL-EEMD-GA-SVR的采煤工作面瓦斯涌出量预测方法及应用

瓦斯涌出量准确预测可为矿井通风及瓦斯灾害防治措施提供重要依据。为提高采煤工作面瓦斯涌出量预测精度,根据陕西黄陵某矿采煤工作面绝对瓦斯涌出量监测数据,应用基于局部加权回归的周期趋势分解(Seasonal-Trend decomposition procedure based on Loess, STL),将监测数据分解成趋势项、周期项和不规则波动项;利用集成经验模态分解(Ensemble Empirical Mode Decomposition,EEMD),将不规则波动项分解得到不同特征尺度的IMFs(Intrinsic Mode Functions, IMFs)分量以及残差余量;通过遗传算法(Genetic Algorithms, GA)参数寻优后的支持向量回归机(Support Vector Regression, SVR),对各项分解数据进行预测;叠加各分量模型预测结果,得到最终瓦斯涌出量预测结果。结果表明：在预测集为247、147和70组3种情景下,对比分析了STL-EEMD-GA-SVR模型(简称SEGS)、EEMD-GA-SVR模型、GA-SVR模型和高斯过程回归(Gauss...     

基于量纲分析的非充分采动导水裂缝带高度预测

为准确预测非充分采动导水裂缝带高度,选取开采厚度M、煤层埋深H、工作面倾斜长度L、煤层倾角α、覆岩力学性质R、覆岩结构特征S为非充分采动导水裂缝带高度主要影响因素。采用量纲分析建立了导水裂缝带高度与M,H,L,α,S间的无量纲关系式。结合30组实测数据,采用多元回归得到无量纲关系式的最优函数关系式。选取2个非充分采动工作面导水裂缝带现场实例对预测模型进行了工程验证,预测模型预测结果与实测结果吻合良好,其相对误差分别为3.64%和2.93%,预测模型的预测精度可以满足煤矿安全生产现场需要。     

A multiple-point geostatistical method based on geological vector information

The reproduction of the non-stationary distribution and detailed characteristics of geological bodies is the main difficulty of reservoir modeling. Recently developed multiple-point geostatistics can represent a stationary geological body more effectively than traditional methods. When restricted to a stationary hypothesis, multiple-point geostatistical methods cannot simulate a non-stationary geological body effectively, especially when using non-stationary training images (TIs). According to geologic principles, the non-stationary distribution of geological bodies is controlled by a sedimentary model. Therefore, in this paper, we propose auxiliary variables based on the sedimentary model, namely geological vector information (GVI). GVI can characterize the non-stationary distribution of TIs and simulation domains before sequential simulation, and the precision of data event statistics will be enhanced by the sequential simulation’s data event search area limitations under the guidance of GVI. Consequently, the reproduction of non-stationary geological bodies will be improved. The key features of this method are as follows: (1) obtain TIs and geological vector information for simulated areas restricted by sedimentary models; (2) truncate TIs into a number of sub-TIs using a set of cut-off values such that each sub-TI is stationary and the adjacent sub-TIs have a certain similarity; (3) truncate the simulation domain into a number of sub-regions with the same cut-off values used in TI truncation, so that each sub-region corresponds to a number of sub-TIs; (4) use an improved method to scan the TI or TIs and construct a single search tree to restore replicates of data events located in different sub-TIs; and (5) use an improved conditional probability distribution function to perform sequential simulation. A FORTRAN program is implemented based on the SNESIM.     

Statistical interpretation of shock series in mining

SummaryStatistical Interpretation of Shock Series in Mining Depending on structure of measured data the two different statistical patterns may be employed for estimation of impending bumps in mines using microseismologic measurements. The regional measurements which usually are associated with high energy shocks, may be elaborated by means of statistical patterns, being analogous to those used in general seismology. However, when working out measured data taken from single excavation and originated from low energy shocks the local statistical pattern should be employed. It has been proved that such a model enables the stress rate to be estimated exactly enough to carry safe exploitation.

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ZusammenfassungEine statistische Interpretation von Mewerten zufolge künstlicher Erschütterungen in Steinkohlebergwerken Zur Bewertung des Zustandes der in den Steinkohlengruben bestehenden Bedrohung durch Gebirgsschläge auf der Basis der mikroseismologischen Messungen können zwei unterschiedliche statistische Modelle je nach der Struktur der Meßwerte ausgenützt werden. Die auf bestimmte Region eingeschränkten Messungen, welche im allgemeinen mit Erschütterungen von großem Energieaufwand verbunden sind, können wohl mit Anwendung von derartigen statistischen Modellen bearbeitet werden, die den in der allgemeinen Seismologie üblichen analog erscheinen.Zur Bearbeitung der Meßwerte, die im Zusammenhang mit einem einzigen Arbeitsstand stehen und mit niedrigeren Erschütterungsenergien verbunden sind, soll man das lokale statistische Modell benutzen.Man hat bewiesen, daß dank eines solchen Modelles sich die Spannungen so bewerten lassen, daß eine gefahrlose Anwendung möglich wird.

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RésuméInterprétation statistique des séries de chocs dans les mines de houille Pour l'évaluation de l'état de danger de chocs dans les mines, en se basant sur les mesures microsismologiques, on peut employer deux différents modèles statistiques en dépendance de la structure des données de mesure.Les mesures régionales, qui sont en général liées avec les chocs à grandes énergies peuvent être élaborées à l'aide des modèles statistiques analogues à ceux appliqués en sismologie générale.Pourtant, pour l'élaboration des données de mesure liées un chantier de fond et liées avec les basses énergies des chocs il faut appliquer le modèle statistique local.On a démontré que, grâce à un tel modèle on peut évaluer l'état de tension qui conditionne la sécurité de l'exploitation.

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Geological and geotechnical aspects of underground coal mining methods within Australia

About one quarter of the coal produced in Australia is by underground mining methods. The most commonly used underground coal mining methods in Australia are longwall, and room and pillar. This paper provides a detailed review of the two methods, including their advantages and disadvantages, the major geotechnical and operational issues, and the factors that need to be considered regarding their choice, including the varying geological and geotechnical conditions suited to a particular method. Factors and issues such as capital cost, productivity, recovery, versatility and mine safety associated with the two methods are discussed and compared. The major advantages of the longwall mining method include its suitability for mining at greater depth, higher recovery, and higher production rate compared to room and pillar. The main disadvantages of the room and pillar method are the higher risks of roof and pillar collapse, higher capital costs incurred as well as lower recovery rate.