LU Kun-lin,ZHU Da-yong,YANG Yang 均质边坡准三维安全系数实用计算曲线

针对三维极限平衡法计算边坡安全系数存在着分析过程繁琐、较难普及推广等诸多不足,建立了一套实用的三维边坡安全系数计算曲线。假设三维滑面为中间圆柱和两端为部分球面的组合滑面,采用基于滑面正应力修正的极限平衡分析方法,计算36 864个均质边坡,根据计算结果绘制该套曲线。依据该套曲线可以得到,（1）根据已知边坡体的相关指标快速获得三维安全系数,能够得到较二维分析方法更准确、更客观的稳定性评价;（2）根据实际坡体的稳定状况反分析获得滑面土体强度参数,有效地克服二维反分析得到滑面土体强度参数偏高的弊端。研究成果可为均质边坡三维稳定性初步评价提供简单、实用的参考依据。     

峰值强度与残余强度对边坡加固的影响研究

现有的边坡加固方案中,基本上都是用岩土的峰值强度来确定边坡的临界滑面和锚固长度。实际上,边坡出现滑动后,滑面保持残余变形和抵抗外部载荷的能力出现了衰减,滑面上的强度只是残余强度,采用一种混合方法进行边坡加固,即用峰值强度来确定边坡的临界滑面,用残余强度来确定锚固长度。研究表明,采用混合方法对边坡进行加固可以提高边坡加固工程的安全性,具有较大的实际意义。     

Stability design charts for homogeneous slopes under typical conditions based on the double shear strength reduction technique

Based on a brief review of the existing shear strength reduction (SSR) techniques, the objective function of the comprehensive safety factor for simple homogeneous slopes is established by combining the double SSR technique (considered the shortest pathway of the strength reduction) with the upper bound limit analysis theorem, leading to a strict upper bound on the safety factor. Combining nonlinear sequential quadratic programming (SQP) with the random walk method, the value of the comprehensive safety factor can be optimized, avoiding the trap of a local minimum. Compared with classical examples, the present method is a conservative and effective method for slope stability evaluation. A set of design charts for homogeneous slopes under simple and typical conditions, such as surcharge load, pore water pressure, and seismic loading are produced by the analysis of substantial data, which can eliminate the necessity for iterations when calculating the safety factor. These stability charts are presented in a convenient manner to determine the comprehensive safety factors and corresponding failure patterns under different typical conditions, which might be preferred by engineers for performing the preliminary evaluations of slope safety. Several examples are used to illustrate the application of these stability charts under different conditions.     

基于TBM掘进参数的岩石强度估算方法探讨

隧道盾构掘进机(TBM)掘进时难以及时地、有效地评估掌子面岩石强度,导致现场施工过程中很难客观地判别岩爆、卡机等施工风险。在前人研究成果和工程实践的基础上,提出一种基于TBM掘进参数的现场岩石强度快速估算方法,对掌子面岩石强度进行实时评价。通过TBM规格、掘进参数与岩石强度的力学分析,建立了现场岩石强度快速估算公式。基于对国内外多条隧道TBM数据的统计拟合分析,确定了估算公式中系数常量与TBM参数(开挖直径、刀具尺寸)的相关性,以多个典型TBM工程实例进一步验证了所提经验公式的普适性与可靠性。研究结果可为TBM工程岩石强度的快速现场估算提供新的切实可行的思路。     

Input parameters for estimating seismic loading

The estimation of seismic loading requires both the featuring of the seismotectonic environment as well as a prognosis of site-specific strong ground-motion parameters. Due to the long recurrence times of larger events, there is a lack of high quality strong motion recordings at many sites. The use of seismograms obtained from different seismotectonic regions, additionally recorded under different subsoil conditions, poses several questions as to the significance of the assessment of seismic loading. A way to overcome these problems is the generation of synthetic seismograms, e.g. by the use of Boore's stochastic procedure. Subsoil conditions may be explicitly included in the simulation as proposed by Kunze et al. In this context, the seismotectonic environment forms the deterministic frame of any stochastic strong ground-motion simulation. In terms of Boore's approach, seismic moment, global stress drop, high frequency cut off, and focal depth act as controlling parameters. In order to achieve a more realistic assessment of possible seismic loading, a classification of seismoactive zones should account for parameter vectors as described above rather than for single parameters like magnitudes or intensities. A tool to attack this task may be found in cluster analysis, which is a type of pattern recognition based on statistical considerations. Crucial to this technique, however, is the use of properly estimated parameters, which still cause discussion in the seismological community. Problems and chances of the approach are discussed with examples from the Swabian Jura and the Rhine graben.Paper presented at the 21st General Assembly of the European Seismological Commission held in Sofia, 1988.     

分析含水层水位恢复数据的多次直线解析法

提出了一种分析含水层抽水试验中水位恢复数据的新方法。在方法的建立过程中,考虑了地下水位在上升和下降过程中,含水层的的释水系数和贮水系数之间可能存在着的差异。对表示水位恢复阶段降深变化表达式中的两个表达式都采用了相同的简化方式,即对由于持续抽水引起的降深项和停抽时刻开始的虚拟注水引起的降深项,均采用了保留Theis井函数的级数表达式中前三项作为其简化式,简化条件为无量纲时间 和 。在这样的简化条件下,建立了具有同时能够确定含水层导水系数、贮水系数和释水系数的方法。根据贮水系数和释水系数是否相等,可以判断含水层水位下降与水位恢复过程的形变是否可逆。最后,通过算例说明了方法的应用步骤。     

砂沟滴灌技术参数模型

在分析砂沟滴灌土壤入渗规律的基础上,根据水量平衡原理建立了求解砂沟滴灌技术参数(沟宽、沟高、透水边壁高度、滴头流量)的模型,并将恒定水头积水入渗试验和Philip模型用于求解模型中的土壤入渗性能。以该模型计算的技术参数为基础,通过砂沟滴灌试验验证了模型的可行性,并对影响模型精度的因素做出了分析。试验结果表明,该模型能够较精确地设计砂沟滴灌技术参数。二维恒定水头积水入渗试验中,土壤吸渗率和渗透率是灌水时间的函数,砂沟滴灌中变化的积水深度和湿周是影响模型精度的另一个因素。     

An empirical approach to estimating population parameters from censored fracture-length distributions

Most fracture data sets are length-censored because of incomplete exposure at the surface, so estimating values of parameters of the sampled populations is difficult. Unless the form of the distribution function of the population is known, or one which is analytically tractable is assumed, length-censoring presents formidable problems in determining population parameters. Tests conducted on experimental fracture patterns developed in clay samples subjected to simple shear loading are the basis of a distribution-free way to estimate population parameters. Comparison of random samples of censored and uncensored fracture lengths shows that a useful, homogeneous data set consists of those cracks which lie entirely within the sampling area (two-ended cracks). The properties of this data set can be used to estimate the mean and variance of uncensored data. Estimates of the maximum fracture length of uncensored data, using the variance and maximum length of these two-ended cracks, show good agreement with measured values. Knowledge of the mean, variance, and maximum value of fracture-length populations are of interest in engineering and hydraulic studies, as well as in remote sensing studies of the Earth and other planets. Application of these results to data on rock masses are subject to the caveat that different crack-growth mechanisms in clay and rock may affect the accuracy of the calculations.     

分析隔水边界附近抽水-恢复试验数据的新方法

为能同时分析含水层具有直线隔水边界条件下,抽水试验中抽水―恢复阶段降深数据,提出了一种新的数据分析方法。在建立这种方法时,将表示抽水和恢复阶段水头降深表达式中Theis井函数的级数表达式的前3项作为其近似表达式,经过推导,分别得到抽水和恢复2个阶段的直线方程。2个直线方程的因变量和自变量均为观测数据的函数,而直线常数为待求参数的函数,在进行数据分析时,只要将试验观测数据分别转化为直线方程的因变量和自变量数据,就能够利用一元线性回归法分别计算2个直线方程的常数,而利用直线常数的表达式,能够推导得到计算含水层参数和映射井到观测孔间距离的公式。通过算例说明了方法的具体应用步骤。     

一种长期观测资料确定弱透水层参数的方法

弱透水层是含水层系统的重要组成部分,要准确计算弱透水层释水量和变形量需事先确定弱透水层的渗透系数和贮水率值。基于一维含水层系统概念模型,在相邻含水层降深随时间线性增大的边界条件下,推得了无量纲形式的弱透水层降深解析解,分析了弱透水层中滞后降深消散规律。根据水量均衡方程得到了弱透水层累计压缩变形量随时间变化的标准曲线,并提出了一种配线法用以确定弱透水层的渗透系数和贮水率,该配线法能够反映弱透水层释水变形过程的滞后性。以上海含水层系统为例,运用配线法确定了f_(10-7)分层标处第2弱透水层的渗透系数为4.26×10~(-10)m/s,贮水率为2.22×10~(-4)m~(-1)。对于具有长序列变形和水位观测资料的含水层系统,该方法具有一定的适用性。     

A method to define the palaeowind strength from lacustrine parameters

Gravelly beach ridges, which are formed solely by swash processes, may accurately reflect past wave conditions. The thickness (or height) of a gravelly beach ridge approximately equals the height of wave inundation, which is the sum of the surge and wave run‐up. Their ancient counterparts, if well‐preserved and identified, can be used to estimate palaeowave conditions, which can later be converted to palaeowind intensities based on wind–wave relationships. A technique is described for estimating the palaeowind speed in this paper, which is referred to as the gravelly beach‐ridge thickness technique. By comparing these estimates with instrumental wind records obtained at a modern lake, Qinghai Lake in north‐western China, the beach‐ridge thickness technique is shown to be useful for estimating the average wind speed (V _avg). When applying this method to ancient fetch‐limited basins, five parameters are necessary: (i) the thickness of the isolated gravelly beach ridge; (ii) the average depth of the water body; (iii) the palaeofetch; (iv) the angle between the palaeowind direction and the normal to the shoreline; and (v) the particle size. This technique was applied to an ancient example in the Eocene Dongying Depression, located in eastern China. The results indicate that the average wind speed of the northern wind ranged between 2·27 m sec⁻¹ and 8·36 m sec⁻¹ from 45·0 Ma to 42·0 Ma, and displayed a generally decreasing trend that included early strengthening followed by weakening and later strengthening during this period. The beach‐ridge thickness technique provides a new perspective on delineating palaeowind conditions and can be applied to ancient fetch‐limited basins with gravelly beach ridges worldwide. Generally, if a water body is sufficiently large (fetch exceeding 40 km), deep (average depth exceeding 10 m) and waves (or winds) are determined to approach the shoreline with high angles (angle of incidence <35°), then the calculation errors will be small to negligible.     

煤田火区碳排放量计算模型和关键参数研究

完善碳排放清单,是进行减排工作的基础,为了查明煤田火区对大气碳排放的贡献量,以煤氧复合作用学说为理论基础,从不同的研究思路出发,提出了烧失煤量法和排放通量法两种火区碳排放量计算模型。在明确模型中关键参数“释放因子”“排放系数α”“排放通量”“排放系数β”的具体含义的基础上,重点对各参数所对应的获取途径进行了研究论述：(1)释放因子通过在室内进行煤自燃模拟实验得出;(2)排放系数α通过煤岩吸附实验结合火区实地勘测得出;(3)排放通量通过对火区现场煤自燃气体排放及环境因素的实时监测得出;(4)排放系数β通过对遥感图像裂隙信息的提取得到。上述两种计算模型在我国乌达实验区进行了实际应用,并对其可实现性进行了检验。     

地震效应下非线性抗剪强度参数对裂缝边坡稳定性影响的上限解析

基于非线性Mohr-Coulomb破坏准则,结合极限分析上限法和拟静力分析法,建立功能方程,推导了地震效应下裂缝边坡的安全系数计算方程。采用数学规划方法,计算了不同参数组合条件下的边坡安全系数值,详细分析了非线性条件下一系列参数对边坡稳定性的影响。研究表明,边坡安全系数随非线性参数和地震效应的增大而减小。对比分析可知,在非线性破坏准则下,裂缝深度较大时,裂缝对边坡稳定性影响显著,且边坡越陡影响越大;当裂缝深度超过某个值后,临界破坏面起始端可能不穿过裂缝最底端,而是从裂缝中间某部位穿过。在地震效应作用下,非线性抗剪强度参数对安全系数影响显著。研究成果进一步完善了裂缝边坡稳定性分析内容,所列图表为边坡的设计与施工提供有益参考。     

岩体边坡中流体包裹体参数的逐步回归分析

以白鹤岭铁路隧道岩体边坡为例,在垂直边坡面的4条剖面上采集了不同变形和破坏状态岩石中的16个定向样品,测定了流体包裹体迹面（FluidInclusionPlane简称为FIP）特征参数（包括FIP的长度、形态、连通性、闭合性、粗糙度、交叉性质等参数）与包裹体热动力学参数（包括FIP中包裹体的均一温度、均一压力、包裹体流体密度、流体包裹体成分和氧逸度等参数）。同时,将样品中裂隙分布的分形维数作为描述岩石变形破坏状态的定量指标,采用反馈式逐步回归方法分析这些分形维数与所选7个FIP参数的定量关系。分析表明,影响岩体变形和破裂的主要微观参数包括两个FIP特征参数（即粗糙度系数和分布密度）和两个包裹体热力学参数（即水溶液包裹体均一温度和CO2-H2O包裹体均一温度）。由于岩体的变形和（或）破坏不仅可使FIP中包裹体成分泄漏、也会使FIP迹面特征参数和包裹体热动力学参数发生改变,因此,岩体边坡中流体包裹体参数的逐步回归分析结果对进一步研究岩体变形破坏过程与边坡稳定性将具有重要的参考价值。     

岩石抗剪强度参数的理论概率分布形态研究

岩石抗剪强度参数的概率分布形态是岩石工程可靠度分析和设计的基础。在考虑完整岩石压缩强度为服从正态分布随机变量的条件下,针对Mohr-Coulomb和Drucker-Prager屈服准则的线性系数形式,基于随机变量函数分布理论推导出岩石抗剪强度参数内摩擦角 和黏聚力 的概率密度函数。 和 概率密度函数显示：不仅岩石压缩强度和抗剪强度参数概率分布具有非一致性,而且根据不同屈服准则计算得出的岩石抗剪强度参数概率分布也具有非一致性。在进一步分析屈服准则系数具有不同变异系数和相关系数时的抗剪强度参数概率密度函数特征的基础上,提出根据概率分布的偏度和峰度确定一般情况下抗剪强度参数概率分布形态的方法,从理论上解决岩石压缩强度与抗剪强度参数分布的协调性问题。最后,对大理岩常规三轴压缩试验得出的抗剪强度参数进行大样本统计分析,验证了其概率密度函数理论推导的正确性以及概率分布形态确定方法的合理性。该研究为实际岩石强度概率分析时选择抗剪强度参数合理概率分布形式提供了理论指导。     

On estimating the parameters in mixtures of circular normal distributions

The method of maximum likelihood used in analyzing data which are bimodal in the range (0, )is lengthy and not always successful. Two alternative methods are proposed and the results compared with those obtained by using the method of maximum likelihood on orientation data from clasts and shells. It is shown that a procedure based on the Method of Moments gives comparable results and is much more practicable.     

旁压试验在苏通大桥地质勘察工程中的应用

详细介绍了旁压试验的使用方法,以及受潮汐影响的大桥勘察旁压原位测试中的特殊处理措施,分析了旁压试验中各强度参数指标的处理方法和原则,并运用这些方法和原则处理了苏通大桥旁压试验的强度参数指标,为大桥的设计提供了设计强度参数,也可为同类工程提供参考意义。     

Identification of representative slip surfaces for reliability analysis of soil slopes based on shear strength reduction

Although a slope may have numerous potential slip surfaces, its failure probability is often governed by several representative slip surfaces (RSSs). Previous efforts mainly focus on the identification of circular RSSs based on limit equilibrium methods. In this paper, a method is suggested to identify RSSs of arbitrary shape based on the shear strength reduction method. Monte Carlo simulation is used to generate a large number potential slip surfaces. The RSSs are identified through analyzing the failure domains represented by these samples. A kriging-based response surface model is employed to enhance the computational efficiency. These examples shows that the RSSs may not always be circular, and that the suggested method can effectively locate the RSSs without making prior assumptions about the shape of the slip surfaces. For the examples investigated, the system failure probabilities computed based on the shear strength reduction method are comparable to, but not the same as those computed based on the limit equilibrium methods. The suggested method significantly extends our capability for identifying non-circular RSSs and hence probabilistic slope stability analysis involving non-circular slip surfaces.     

A practical procedure for searching critical slip surfaces of slopes based on the strength reduction technique

Once an earth slope is led to the limit equilibrium state by means of the finite element–strength reduction technique, a plastic zone will go through the slope from the toe to the top. Based on the observation that the critical slip surface will be within the plastic zone and be composed of the points at which the equivalent plastic strain arrives at the maximum in the vertical direction. First, some vertical lines are arranged along the horizontal direction. Then, along each of the vertical lines the point with the maximum equivalent plastic strain is found out. All such points take on a shape of wave and form the functional data. Finally, the functional data are smoothed by the least squares and the position of the critical slip surface is determined. The proposed procedure is verified through comparison with other procedures.     

岩体抗剪强度参数的线性优化方法

针对岩体结构面力学参数的重要性,以大量工程实例为依据,以统计误差分析相关理论为基础,研究最小二乘法与M-估计法在分析结构面抗剪强度参数时的适用性。研究结果表明,在难以判断粗差的数量和比例时,很难对两种线性回归方法的优劣进行规律性的比较。考虑到数据是具有工程特性的,为更准确地处理实验数据,在以上两种方法的基础上提出了一种新的实验数据处理方法,并应用于计算李家河水库的抗剪强度参数。