宝鸡─常兴源农灌区斜坡环境的变异研究

在黄土台源农灌区，其天然斜坡环境常被农田灌溉所变异，形成农灌工程地质斜坡环境。在此种环境中，斜坡的变形和破坏常被诱发、激活和加剧，从而产生了新的农灌斜坡环境工程地质问题。若对其进行治理，必须从农田灌溉诱发、激活和加剧灌区内斜坡变形和破坏这一观点进行考虑．本文试图以宝鸡─常兴源农灌区斜坡的环境工程地质问题为例，对上述观点进行阐述。     

延安市凤凰山东北麓滑坡危险斜坡的变形特征及稳定性分析

通过对凤凰山东北麓工程地质特征的分析．指出该区存在的不良地质问题有滑坡(滑塌)以及危险斜坡等，并对各滑坡(滑塌)以及危险斜坡的变形破坏特征进行了分析，最后运用斜坡(滑坡)稳定性计算中常用的瑞典法、毕肖普法和剩余推力法对其进行了稳定性验算，为凤凰山东北麓后期的治理设计提供了依据。     

三峡库区湖北省夷陵区陈家冲斜坡的稳定性分析及治理对策

在介绍三峡库区湖北省夷陵区陈家冲斜坡的工程地质条件和斜坡特征的基础上,对斜坡的稳定性进行定性分析和定量计算,根据斜坡的危害程度结合斜坡周边环境条件提出了治理方案。     

恩施盆地典型红砂岩斜坡破坏机理试验研究

恩施城市建设中盆地内红砂岩斜坡破坏较为严重,其中结构面控制的逆向红砂岩斜坡破坏现象普遍。以恩施市内凤凰山公园斜坡为典型实例,研究其变形破坏过程与机理。工程地质调查与室内岩体物理力学试验研究表明,该类红砂岩斜坡破坏的影响因素为斜坡地质结构构造、地层岩性与工程诱发因素。基于物理模型试验再现了该类斜坡失稳破坏的全过程,通过坡体位移监测、有机玻璃投影监测与宏观变形拍照记录分析了斜坡的变形破坏机理,并采用离散元法数值模拟对比验证了该类斜坡破坏机理。结果表明,该类斜坡的稳定性状态主要由结构面控制,在工程开挖的作用下,斜坡沿结构面必发生失稳破坏。鉴于此,工程建设中必需对该类斜坡进行合理的边坡设计,防止出现不同规模的失稳滑动现象。      

歧口凹陷板桥斜坡区新生代断裂特征及油气地质意义

歧口凹陷发育多类型斜坡构造,为地层岩性油气藏主要富集区。板桥斜坡为歧口凹陷西缘受边界断裂控制的旋转掀斜型斜坡,斜坡内断裂特征复杂。在钻井及高分辨地震三维解释基础上,对板桥斜坡区内断裂特征进行分析,并探讨其油气地质意义。研究表明,板桥斜坡内部发育3组不同类型的断裂系,其组合类型、变形特征及成因机制具有显著差异。西侧的大张坨平行断裂系受控于差异伸展作用,缓岸带一侧发育一组平行排列的张性断裂,断裂走向与斜坡倾向垂直,形成断鼻背景上的单一斜坡构造;东侧的长芦羽状断裂系及高沙岭帚状断裂系形成受伸展走滑作用共同控制,断裂走向与地层倾向平行,形成顺向复杂断裂斜坡构造。斜坡区演化经历了初始裂陷期-旋转掀斜期-坳陷沉降期3个阶段,控制了斜坡区古地貌特征、沉积体系类型及砂体展布。断裂活动特征的差异则控制了油气运聚特征的不同,早衰型断裂易于油气短距离运移在中深部富集成藏,继承型断裂两侧具多目的层立体含油的特征。      

珠江口盆地惠西南地区转换斜坡类型及其控藏作用

综合利用地震、钻井、油藏及地球化学资料,对珠江口盆地惠西南地区转换斜坡特征及其对油气的垂向输导作用开展了研究。研究揭示研究区发育了开放型、连接型和破坏型3类转换斜坡,已探明的油藏主要分布在转换斜坡附近或与其相连构造脊的圈闭内。3类转换斜坡对油气的垂向输导能力存在差异,破坏型转换斜坡的垂向输导性最强,与其相关的中浅层油藏储量大、充满度高;开放型转换斜坡的垂向输导性最弱,与其相关的中浅层油藏几乎不发育;连接型转换斜坡的垂向输导性则介于前两者之间。转换斜坡内微裂隙发育程度的差异决定了其垂向输导油气能力的强弱,利用位移-距离法分析认为形成破坏型转换斜坡的应力最强,微裂隙最发育,导致其垂向输导能力最强。转换斜坡输导油气差异性的认识可为珠江口盆地的油气勘探提供指导。      

面向区域滑坡易发性精细化评价的改进斜坡单元法

易发性评价是区域滑坡灾害风险预警与稳定性分析的基础,针对乡镇尺度的大比例尺精细化滑坡易发性评价,传统基于水文学和地貌学的斜坡单元划分方法难以满足评价精度。针对以上问题,以重庆市万州区大周镇为实例验证对象,形成了适用于精细化评价的改进斜坡单元划分方法。首先从斜坡地质环境孕灾规律出发,综合考虑地形地貌、物质组成、斜坡结构和灾害类型的均一性要求,提出了基于斜坡地质环境一致性的改进斜坡单元划分方法,选择重庆市万州区大周镇为实例验证对象,并与水文分析法、曲率分水岭法进行了对比分析。结果表明：(1)改进斜坡单元法划分的评价单元大小均匀性较好,未出现细碎单元或畸形长条状单元;(2)评价单元的总体形态特征更为合理,形态指数集中在1～2之间,呈现圆形或正方形斜坡形态;(3)改进斜坡单元划分的结果与已有灾害边界范围的叠加重合度最高,能更好地体现滑坡易发性评价或稳定性分析物理意义。研究结论对提高区域滑坡易发性评价的准确性与精度具有重要借鉴意义。     

延安市区斜坡稳定性两级模糊综合评判

本文采用两级模糊综合评判方法,在对延安市区斜坡稳定性进行定性分析和评价的基础上,选取主要影响因素作为评价指标并将其定量化,然后按不稳定、次不稳定、基本稳定和稳定等四个级别进行了延安市区斜坡稳定性两级模糊综合评判。评判结果较好地反映了市区斜坡带的实际稳定程度。该方法清晰易用,能使较多的影响因素参与评判,是进行斜坡稳定性定量化研究的一个有效途径。     

强震作用下斜坡表面放大效应的三维离散元模拟

为研究强震作用下斜坡表面的动力放大效应, 以陕西勉县某岩质斜坡为例, 建立了三维模型。运用离散元软件3DEC, 模拟了动力条件下斜坡的变形失稳过程, 分析了斜坡表面的动力响应特征, 研究了不同地震波输入工况条件下坡体表面动力响应差异。研究结果表明: 考虑地震纵波的影响时, 竖向加速度得到显著增强, 坡面的PGA放大系数增强了约1.62倍; 坡面形态强烈影响着斜坡表面的动力响应特征, 强震作用下, 斜坡坡肩及坡形转折处的放大效应均十分强烈, 凸出部位次之, 坡表两侧的放大效应最弱; 不同输入工况下, 斜坡坡形转折处的水平向PGA放大系数均维持较高值, 特别是在仅输入水平向加速度的条件下, 该部位在地震滑坡灾害预防中应特别注意; 强震作用下滑坡的运动过程可概括为滑坡孕育启动阶段—挤压碰撞高速运动阶段—堆积阶段。研究成果可为该地区防灾减灾工作提供一定理论支持。      

模糊模型判识在斜坡破坏危险性分区中的应用

本文在探讨斜坡破坏危险性分区中,试用模糊模型判识方法,依斜坡演变趋势与影响因素间的关联性,进行模糊聚类和相容度的分析,从而对斜坡破坏危险性做以分级分区研究并对斜坡的环境质量做以评价。     

Dynamic failure mode and energy-based identification method for a counter-bedding rock slope with weak intercalated layers

The dynamic failure mode and energy-based identification method for a counter-bedding rock slope with weak intercalated layers are discussed in this paper using large scale shaking table test and the Hilbert-Huang Transform (HHT) marginal spectrum. The results show that variations in the peak values of marginal spectra can clearly indicate the process of dynamic damage development inside the model slope. The identification results of marginal spectra closely coincide with the monitoring results of slope face displacement in the test. When subjected to the earthquake excitation with 0.1 g and 0.2 g amplitudes, no seismic damage is observed in the model slope, while the peak values of marginal spectra increase linearly with increasing slope height. In the case of 0.3 g seismic excitation, dynamic damage occurs near the slope crest and some rock blocks fall off the slope crest. When the seismic excitation reaches 0.4 g, the dynamic damage inside the model slope extends to the part with relative height of 0.295-0.6, and minor horizontal cracks occur in the middle part of the model slope. When the seismic excitation reaches 0.6 g, the damage further extends to the slope toe, and the damage inside the model slope extends to the part with relative height below 0.295, and the upper part (near the relative height of 0.8) slides outwards. Longitudinal fissures appear in the slope face, which connect with horizontal cracks, the weak intercalated layers at middle slope height are extruded out and the slope crest breaks up. The marginal spectrum identification results demonstrate that the dynamic damage near the slope face is minor as compared with that inside the model slope. The dynamic failure mode of counter-bedding rock slope with weak intercalated layers is extrusion and sliding at the middle rock strata. The research results of this paper are meaningful for the further understanding of the dynamic failure mode of counter-bedding rock slope with weak intercalated layers.     

基于GridMet模型的浙江省温湿指数空间分布及地形影响分析

温湿指数是气候舒适度评价模型之一,通过温度与湿度的组合反映人体与周围环境的热量交换,本文利用2003-2018年浙江省及其周边71个气象站点月平均气温、地面水汽压数据,以及MODIS水汽产品,基于GridMet模型模拟了浙江省各月温湿指数空间分布（100 m×100 m）,分析了浙江省温湿指数随地形因子（海拔、坡度、坡向）变化的特征;讨论了各地形因子对温湿指数空间分布的影响程度。结果表明：① 海拔、坡度、坡向3个地形因子中,1月温湿指数随坡向的变化最大,7月最小;② 同坡向上,坡度变化对1月温湿指数影响较大,而海拔变化则是对7月影响最大;③ 南坡1月温湿指数随海拔和坡度增加均略为增加,南坡其他月份及北坡各月均为随海拔和坡度增加温湿指数减小;④ 北坡相对于南坡而言,海拔和坡度对温湿指数的影响更为明显。浙江大部分山区由于地形影响,夏季较为“舒适”,适宜建立避暑消夏的旅游项目。     

极限平衡方法在夏日哈木镍钴矿山拟建露天采场边坡角优化中的应用

夏日哈木镍钴矿为大型镍钴硫化物矿床,现拟建大型露天采场,边坡采用分台阶式高边坡,最高边坡高度超过600m。该工程具有开挖成本高,边坡一但失稳后果严重的特点。为此需要选择一个即节约经济成本又保障整体边坡稳定的最佳边坡角。本文采取Geostudio软件中的Slope模块极限平衡方法对拟建露天采场假设开挖边坡角的整体边坡稳定性进行分析,提出最佳设计边坡角。　本次边坡角优化的思路：首先根据场地工程地质条件和拟建边坡的高度等因素将拟建边坡划分为5个区,选择典型边坡工程地质剖面并进行工程地质岩体分段,然后通过岩石强度指标折减计算（本文采用费辛柯法、M.Georgi法和经验法）给各分段的岩体赋予凝聚力、内摩擦角等计算参数,采用极限平衡方法（Geostudio软件中的Slope模块法）对不同角度下对各分区边坡的破坏形式及安全系数进行计算,最后提出了各分区边坡的最佳设计边坡角。     

The characteristics of rill development and their effects on runoff and sediment yield under different slope gradients

Rill formation is the predominant erosion process in slope land in the Loess Plateau, China. This study was conducted to investigate rill erosion characteristics and their effects on runoff and sediment yielding processes under different slope gradients at a rate of 10°, 15°, 20° and 25° with rainfall intensity of 1.5 mm min-1 in a laboratory setting. Results revealed that mean rill depth and rill density has a positive interrelation to the slope gradient. To the contrary, width-depth ratio and distance of the longest rill to the top of the slope negatively related to slope gradient. All these suggested that increasing slope steepness could enhance rill headward erosion, vertical erosion and the fragmentation of the slope surface. Furthermore,total erosion tended to approach a stable maximum value with increasing slope, which implied that there is probably a threshold slope gradient where soil erosion begins to weaken. At the same time, the correlation analysis showed that there was a close connection between slope gradient and the variousindices of soil erosion: the correlation coefficients of slope gradient with maximal rill depth, number of rills and the distance of the longest rill from the top of the slope were 0.98, 0.97 and-0.98, respectively,indicating that slope gradient is the major factor of affecting the development of rills. Furthermore,runoff was not sensitive to slope gradient and rill formation in this study. Sediment concentration,however, is positively related to slope gradient and rill formation, the sediment concentrations increased rapidly after rill initiation, especially. These results may be essential for soil loss prediction.     

Evaluation of the stability of vegetated slopes according to layout and temporal changes

Vegetation in slopes can effectively improve slope stability.However,it is difficult to estimate the effects of vegetation on slope stability because of variations in plant species and environmental conditions.Moreover,influences of plant growth on slope stability change with time,resulting in changes in the safety factor.This study was conducted to evaluate the stability of vegetated slopes with time and investigate the effects of different layouts of plant species on slope stability.Here,we used a plant growth model and slope stability analysis to build an evaluation model.To accomplish this,one species of tree,shrub and grass was chosen to set six layout patterns.A slope with no vegetation served as a control.The safety factors of the seven slopes were then calculated using the developed evaluation model and differences in the safety factors of slopes were compared and discussed.The slope vegetated with Platycladus orientalis reached the most stable state at the age of 60 years.Shrub slope(Vitex negundo)had the maximum safety factor after 20 years.Overall,the safety factor of vegetated slopes increased from 12.1%to 49.6% compared to the slope with no vegetation.When wind force was considered,the safety factor value of the slope changed from 3.5%to 43.5%.Vegetation mixtures of trees and grasses resulted in the best slope stability.Planting grasses on slopes can improve slope stability of trees to a greater degree than that of slopes with shrubs in the early stage of growth.     

DEM分辨率与平均坡度的关系分析

由DEM提取坡度时,DEM分辨率的变化会造成局部栅格提取的坡度数值的变化,其变化规律对于深刻理解平均坡度,随DEM分辨率的变化而变化的规律具有现实意义。在黄土高原的研究中,选择了8个典型地貌类型的样区,获得了以1:10 000比例尺地形图为数据源的DEM(分辨率为5 m)。从DEM分辨率对栅格坡度影响规律的分析中,得到如下结论:(1)随着DEM分辨率粗略化,所提取的坡度平均值有可能升高;(2)在所有样区,随DEM分辨率粗略化,负误差的栅格均是正误差的栅格数量的1.13倍以上,保持负误差的栅格是保持正误差的栅格数量的1.81-4.04倍,同时坡度的负误差均值是正误差均值变化幅度的3.1倍以上;(3)结合结论(2)和本文提出的指标,可准确地解释8个样区中坡度平均值随DEM分辨率变化而变化的规律;(4)DEM的分辨率对正负误差的栅格数量没有明显影响,正误差(或负误差)栅格均集中于个别坡度的分级区间,而DEM分辨率对此集中的区间没有明显影响;(5)坡度总体误差可根据本研究所提出的经验公式由DEM分辨率和分辨率为5 m的DEM所提取坡度的平均值计算出来。     

Slope wavenumber spectrum models of capillary and capillary-gravity waves

Capillary and capillary-gravity waves possess a random character, and the slope wavenumber spectra of them can be used to represent mean distributions of wave energy with respect to spatial scale of variability. But simple and practical models of the slope wavenumber spectra have not been put forward so far. In this article, we address the accurate definition of the slope wavenumber spectra of water surface capillary and capillary-gravity waves. By combining the existing slope wavenumber models and using the dispersion relation of water surface waves, we derive the slope wavenumber spectrum models of capillary and capillary-gravity waves. Simultaneously, by using the slope wavenumber models, the dependence of the slope wavenumber spectrum on wind speed is analyzed using data obtained in an experiment which was performed in a laboratory wind wave tank. Generally speaking, the slope wavenumber spectra are influenced profoundly by the wind speed above water surface. The slope wavenumber spectrum increases with wind speed obviously and do not cross each other for different wind speeds. But, for the same wind speed, the slope wavenumber spectra are essentially identical, even though the capillary and capillary-gravity waves are excited at different times and locations. Furthermore, the slope wavenumber spectra obtained from the models agree quite well with experimental results as regards both the values and the shape of the curve.     

Experimental study of motion characteristics of rock slopes with weak intercalation under seismic excitation

In order to investigate the effect of a weak intercalation on slope stability, a large-scale shaking table model test was conducted to study the dynamic response of rock slope models with weak intercalation. The dynamic response of the prototype slopes were studied in laboratory with the consideration of law of similitude. The initiation failure was observed in the rock slope model with a counter-tilt thin-weak intercalation firstly, not in the slope model with a horizontal thin-weak intercalation. Furthermore, it was interesting that the fracture site is shifted from crest top to the slope surface near the weak intercalation, which is different with the location of failure position in a normal layered slope. We also discussed the effect of the dip angle and the thickness of weak intercalation on the failure mechanism and instability mode of the layered rock slope. From the experimental result, it was noted that the stability of the slope with a counter-tilt weak intercalation could be worse than that of the other slopes under seismic excitation. The findings showed the difference of failure in slopes with a horizontal and counter weak intercalation, and implicated the further evaluation of failure of layered slopes caused by seismic loads.     

Effect of lithology and structure on seismic response of steep slope in a shaking table test

Studies on landslides by the 2008 Wenchuan earthquake showed that topography was of great importance in amplifying the seismic shaking, and among other factors, lithology and slope structure controlled the spatial occurrence of slope failures. The present study carried out experiments on four rock slopes with steep angle of 60° by means of a shaking table. The recorded Wenchuan earthquake waves were scaled to excite the model slopes. Measurements from accelerometers installed on free surface of the model slope were analyzed, with much effort on timedomain acceleration responses to horizontal components of seismic shaking. It was found that the amplification factor of peak horizontal acceleration, RPHA, was increasing with elevation of each model slope, though the upper and lower halves of the slope exhibited different increasing patterns. As excitation intensity was increased, the drastic deterioration of the inner structure of each slope caused the sudden increase of RPHA in the upper slope part. In addition, the model simulating the soft rock slope produced the larger RPHA than the model simulating the hard rock slope by a maximum factor of 2.6. The layered model slope also produced the larger RPHA than the homogeneous model slope by a maximum factor of 2.7. The upper half of a slope was influenced more seriously by the effect of lithology, while the lower half was influenced more seriously by the effect of slope structure.     

Stability analysis of an unsaturated soil slope considering rainfall infiltration based on the Green-Ampt model

Based on the principle of saturated infiltration and the Green-Ampt model, an unsaturated infiltration model for a soil slope surface was established for either constant moisture content, or depth-varying moisture content and the slope. Infiltration parameters in the partially saturated slope were revealed under sustained rainfall. Through analysis of the variation of initial moisture content in the slope, the ponding time, infiltration depth, and infiltration rate were deduced for an unsaturated soil slope subject to rainfall infiltration. There is no ponded water on the surface of the slope under sustained low-intensity rainfall. The results show that the infiltration parameters of an unsaturated slope are influenced by the initial moisture content and the wetting front saturation, the soil cohesion and rainfall intensity under sustained rainfall. More short-term slope failures can occur with the decrease of cohesion of the soil of the slope. The ponding time and infiltration depth differ considering constant or different initial moisture content respectively in the soil slope. Then, best-fit curves of the infiltration rate, ponding time, and infiltration depth to the wetting front saturation were obtained with constant or different initial moisture contents. And the slope failure time is roughly uniform when subject to a rainfall intensity I5 mm/h.