用趋势面分析方法提高模拟退火法反演的效率

利用模拟退火反演过程中废弃的随机搜索的模型解信息, 建立起目标函数的二阶趋势面, 根据趋势面的分析结果预测和指导模拟退火的搜索方向, 使模拟退火法快速地收敛到全局最优解.数值试验证明, 这种方法比传统模拟退火法的计算效率高出十倍以上.      

Slopewash,surface runoff and fine-litter transport in forest and landslide scars in humid-tropical steeplands,luquillo experimental forest,Puerto Rico

Rainfall, slopewash (the erosion of soil particles), surface runoff and fine-litter transport steepland sites in the Luquillo Experimental Forest, Puerto Rico (18° 20’ N, 65° 45’ W) were measured from 1991 to 1995. Hillslopes underlain by (1) Cretaceous tuffaceous sandstone and silstone in subtropical rain (tanonuco) forest with vegetation recovering from Hurricane Hugo (1989), and (2) Tertiary quartz diorite in subtropical lower mantone wet (colorado and dwarf) forest with undisturbed forest canopy were compared to recent landslide scars. Monthly surface runoff on these very steep hillslopes (24° to 43°) was only 0·2 to 0·5 per cent of monthly rainfall. Slopewash was higher in sandy loam soils whose parent material is quartz diorite (averaging 46 g m⁻² a⁻¹) than in silty clay loam soils derived from tuffaceous sandstone and siltstone where the average was 9 g m⁻² a⁻¹. Annual slopewash of 100 to 349 g m⁻² on the surfaces of two recent, small landslide scars was measured initially but slopewash decreased to only 3 to 4 g m⁻² a⁻¹ by the end of the study. The mean annual mass of fine litter (mainly leaves and twigs) transported downslope at the forested sites ranged from 5 to 8 g m⁻² and was lower at the tabonuco forest site, where post-Hurricane Hugo recovery is still in progress. Mean annual fine-litter transport was 2·5 g m⁻² on the two landslide scars. Copyright © 1999 John Wiley & Sons, Ltd.     

Spectral scaling in Mars topography: effect of craters

Extensive computer simulations aimed at testing a hypothesis that impact craters may explain the scaling behaviour of surface spectra are presented. The simulations show that indeed crater effects alone may explain the spectral scaling of Mars’ topography revealed from MOLA data. The range of the scaling exponents obtained for a wide range of simulation parameters does not exceed the limits observed for Mars. The simulations suggest that the shape of large craters is the key factor leading to the two scaling ranges in the surface spectra. Particular values of the scaling exponents may additionally depend on the depth-diameter relationship and the crater size distribution.     

三面临空单薄破碎岩体帷幕灌浆设计与施工尝试

本文阐述了三面临空单薄破碎岩体帷幕灌浆的设计和施工方法，进而讨论和验证了该方法的合理性及效果，同时，本文还讨论了在类似条件下灌浆压力值的确定及施工工艺。工程经灌浆后十余年的检验，证明所采用的设计方案符合工程实际。     

Characterization, lateral variability and lateral extent of discontinuity surfaces on a Carbonate Platform (Barremian to Lower Aptian, Oman)

Hiati of various duration in carbonates are commonly expressed as discontinuity surfaces. The understanding of processes that form and affect these surfaces leads to an improved sequence-stratigraphic interpretation, a reliable outcrop correlation, and better models for reservoir compartmentalization. Various intraformational discontinuities were analysed and interpreted in a well-exposed study window, 2·5 km in lateral length and 60 m in height comprising the Barremian-Aptian Qishn Formation (Haushi-Huqf area, central Oman). This study focuses on the lateral extent and morphology of the surfaces, the petrography of the underlying rocks, and the facies changes and geochemical trends across these discontinuities. Furthermore, the lateral variability of discontinuity surfaces was documented. Three genetic types of discontinuities are differentiated: (i) erosion surfaces; (ii) omission surfaces (hard- and firmgrounds); and (iii) composite surfaces with evidence for both subaerial exposure and submarine boring. Field observations, combined with petrographic and geochemical data, suggest that 17 surfaces are laterally extensive for at least 20 km and record relative sea-level fluctuations of regional scale. In contrast, a large number of laterally limited surfaces (<1 km) are related to locally active processes such as waves and current erosion. The lateral variability along extensive surfaces is the result of the depositional environment below the discontinuity, the sea-floor topography, waves and currents and differential erosion. The most pronounced lateral variability is present along six laterally extensive composite surfaces that record terrestrial exposure and subsequent flooding of a tidal flat environment. This variability is caused by spatial variability in the tidal flat environment, meteoric alteration and differential erosion. This study emphasizes the spatial and temporal complexity of processes that form and modify discontinuity surfaces. This variability must be kept in mind when interpretations and correlations are based on one-dimensional sections or cores.     

适用倾斜滑面的刚性抗滑桩最小嵌固深度计算方法

为计算确定桩前滑面倾斜情况下加固边坡的抗滑桩最小嵌固深度,基于倾斜地面条件的抗滑桩计算地基系数法,确定嵌固段桩侧土层压力,同时采用塑性极限分析方法,推导与滑面倾角密切相关的嵌固段土层极限抗力,并根据桩侧地层最大压力不超过其极限抗力的条件,建立了抗滑桩最小嵌固深度计算方法,并确定了其与滑面倾角的关系。实例分析表明,抗滑桩最小嵌固深度随滑面倾角呈非线性增大,在倾角为10°～30°范围内变化显著;嵌固段地层黏聚力、内摩擦角和重度对抗滑桩最小嵌固深度均有明显影响,且呈负相关关系;本文方法所得桩体最小嵌固深度比传统考虑桩前滑面倾斜影响的方法约小18%。     

贵州兴旺煤矿开采地表塌陷预测方法探讨

以贵州六枝特区兴旺煤矿地表塌陷为例,采用概率积分法作为地表移动及变形预测的模式,选取下沉系数、主要影响角、主要影响半径和水平移动系数为地表移动参数,计算得出井田开采后地表最大下沉值为1425．3mm,影响面积约1．85km^2。并比较说明除移动参数外各类煤柱的留设也是其中需要考虑的因素。     

盾构穿越砂卵石地层地表沉降特征细宏观分析

以成都砂卵石地层中地铁1号线的土压平衡盾构掘进施工为研究背景,采用室内试验、PFC2D二维颗粒流程序和 Plaxis 3D有限元软件对盾构穿越砂卵石地层地表沉降特征进行了细宏观数值模拟,揭示了土压盾构穿越砂卵石地层的失稳机制和沉降规律,并结合实际施工参数和实测地表沉降数据进行了对比分析,获得了土压盾构在砂卵石地层中掘进引起的地表横向沉降槽和纵向沉降槽曲线,分析了不同大小的开挖面土仓压力和盾尾注浆压力对地表沉降的影响,给出了砂卵石地层开挖面土仓压力的建议值和盾尾注浆压力参数的合理取值范围。细宏观分析表明,与注浆压力相比较,土仓压力对地表最大沉降曲线的形状影响较小;但必须关注土仓压力的变化,在砂卵石地层中由于土拱效应对开挖面稳定性影响较大,甚至发生突然坍塌破坏。     

铜（II）在高岭石表面的吸附

在天然天体系中,铜、铅、镉等重金属元素的形态分布、归宿和生物有放性强烈取决于重金属元素在水体颗粒物表面的分配趋势,本文对铜（ＩＩ）在常见的重要粘土矿物－高岭石表面的吸附进行了实难和模式研究,结果表明,在同时考虑自由水合离子Ｃｕ＾２＋和羟基金属郭子ＣｕＯＨ＾＋与高岭石表面络合的情况下,单一表面基团、无静电表面络合模式能很好地描述酮（ＩＩ）的吸附行为。拟合得到的ＣｕＯＨ＾＋的络合常数比Ｃｕ＾２＋的大得     

土体表面三维位移测试的新方法

采用双目立体视觉与数字图像相关相结合的新方法,对静载作用下湿喷桩复合地基室内模型的土体表面三维位移进行测试。给出了双目立体视觉系统的标定结果,提出了提取角点坐标的新方法及基于仿射变换的左右摄像机同名点的匹配搜索法,得到了土体表面三维位移随荷载变化的曲线。试验结果证明,将该系统应用于湿喷桩复合地基室内模型的土体表面位移测试是一种有益的尝试,也为土体位移测试提供了新的方法。