结构面倾角对岩质边坡位移影响的分析

岩体结构面是影响岩质边坡位移及其稳定性的重要因素之一,但是由于数学和力学上的困难,岩体结构面对岩质边坡变形的影响通常难以用理论公式计算得出,目前只能采用数值分析手段。分别针对坚硬岩边坡和软岩边坡中存在软弱结构面的情况,用有限元差分程序FLAC和边坡稳定性系数公式,定量和定性地讨论了岩体结构面倾角对岩质边坡位移的影响。通过计算分析发现,(1)岩体中结构面的存在是影响岩石边坡位移及其稳定性的重要因素之一;(2)随着结构面倾角的增加,边坡的稳定性和边坡的位移可能增加,也可能减小,并不象我们想象的那样随着结构面倾角的增加而增加,必须用定性和定量方法针对具体问题进行具体分析。     

无泥型软弱层带的强度参数

分析表明 ,控制无泥型软弱层带强度参数的主要因素是其物质组成和所赋存的地质环境 (地应力场 )。通过现场和室内完成的大量抗剪试验结果 ,从中建立出强度参数和各控制因素的关系式 ,最终以控制因素的变化规律去揭示软弱层带强度参数的变化规律 ,进而给出不同地段、不同类型软弱层带的强度参数值。     

中国丹霞地貌研究进展

从本世纪３０年代阵国达提出“丹霞地形”的概念以来,中国学者经历了初创、成型和发展三个阶段的研究,作为地貌学一个新领域的丹霞地貌研究已日趋成熟。“红色陆相碎屑岩”作为丹霞地貌的物质基础和“陡崖坡”作为形成２限定为大部分学者所接受。“顶平、身陡、麓缓”的坡面组合,是丹霞地貌 的基本形成特征。目前所发现的红层均早于中生代;大部分丹霞地貌发育在红色砾岩、砂砾岩、砂岩的地层组合上,而相对软弱的粉沙质和泥质岩     

加固含水平软弱层高陡边坡预应力锚索倾角的取值范围

用直线和曲线滑面两种模型，模拟预应力锚索加固含有水平软弱层的高陡边坡的潜在滑动面，通过对锚索加固的力学机理分析来阐述预应力在滑动面主滑方向上产生分力的原因。从锚索受力角度上对锚索倾角的取值范围进行探讨，结合实际造孔过程有不同程度的孔斜或弯曲以及获取较好的锚固灌浆效果，就仰角锚固和俯角锚固两种锚固条件分别得出锚索倾角的取值范围，并以此来判定锚索的预应力是否会在滑动面走向方向上产生不利于坡体稳定的下滑力。     

贵州水城曾家包包大型基岩滑坡的成因机制及稳定性

从滑坡的地质环境入手,通过地质调研及测绘,分析曾家包包大型基岩滑坡的特征、控制因素及成因机制,并运用sama法及不平衡推理法、毕肖普法对滑坡稳定性极限平衡进行计算分析。在此基础上,对在现今应力场作用下滑坡的稳定性采用了有限元模拟,并对模拟的结果进行分析,得出在天然条件下曾家包包滑坡曾处于稳定状态,岩体中的软弱夹层经长期持续的地下水浸润软化逐渐泥化形成倾角上陡下缓的贯通性滑移面,在雨季降雨异常集中期,岩体排水不畅形成较高的空隙水压力,斜坡岩体就会沿滑移面发生顺层滑移,从而形成大型基岩滑坡。     

含水平软弱夹层斜坡变形破坏特征的振动台试验

已有研究结果表明,强度相对较低的软弱夹层会对地震波产生吸收或强化作用,在一定程度上控制了斜坡的地震动力响应及变形破坏特征。试验以振动台为研究手段,设计并完成含不同厚度水平软弱夹层的两个单面斜坡概念模型。通过记录斜坡模型的变形破坏过程,分析其动力响应特征。试验结果表明,斜坡模型的变形破坏与地震动力参数密切相关:1.模型在正弦波激振下较天然波变形明显;2.合成向ZX、水平单向X和竖直单向Z的激振下,变形程度依次减弱;3.随着激振强度增加,变形破坏愈明显。两模型的变形破坏均出现在坡体中上部,且最大破坏深度距坡顶约50 cm。含薄夹层斜坡的破坏范围分布于整个中上部,坡顶近1/2发生变形和滑移破坏,呈现出"拉裂-剪切-滑移-碎屑流化"破坏模式,而含厚夹层斜坡的破坏范围仅集中于软弱夹层以上坡肩以下,两侧未达坡体边缘的局部范围,形成浅表的"凹岩腔",呈现出"震裂-剥落"破坏模式。在相同的加载条件下,含薄夹层斜坡变形破坏先于含厚夹层斜坡。试验模拟再现了含水平软弱夹层斜坡在强震作用下的变形破坏规律,为地震诱发次生地质灾害的研究和防治提供了有力的依据。     

区域经济一体化视角下“行政区经济”约束强度的定量测度及时空演化分析——以成德绵地区为例

“行政区经济”作为行政区划框架下自身发展和区域竞争相互作用的经济运行现象,对区域协调发展影响深远。论文立足于区域经济一体化的视角,构建基于“行政区经济”函数和改进潜能模型的“行政区经济”测度模型,以成德绵地区为例,定量刻画其2005—2018年“行政区经济”约束强度的时空演化特征。研究表明:① 研究期内成德绵地区“行政区经济”约束强度历经“累积上升—快速下降—波动起伏”3个阶段,行政区划对经济一体化的刚性约束总体上呈下降趋势,区域一体化态势明显;② 2009年是其变化的拐点(峰值),各阶段“行政区经济”约束强度变化与政策以及行政区划调整耦合性较强,“行政区经济”测度模型具有较好适用性和合理性;③ 2005—2018年间研究区“行政区经济”类型结构具有阶段性稳步降低的特点,高强度型和60%的中强度型政区转为较低强度型政区,较低强度及以下类型政区占比由51.7%提升至91.4%,表明“行政区经济”的约束强度明显降低,区域一体化水平显著提升;④ 成德绵地区“行政区经济”空间格局经历了“中心极化—中部辐射递减—外围塌陷”的过程,研究区在区域协调发展方面采取了有效的措施且效果显著,推动“行政区经济”重心向南偏西3°方向位移10.08 km。未来还需通过改革行政组织结构和适时推进行政区划调整等途径优化体制机制,弱化行政区划约束,构建良好的一体化发展模式。     

无泥型软弱层带饱水前后强度特性现场试验

针对以粗粒土为代表的软弱层带在水电、铁路等交通领域对边坡及洞室围岩稳定性的控制,结合某水电工程坝区,分别对岩块岩屑型和岩屑夹泥型两种软弱夹层,在考虑一定围压作用下进行了天然含水状态和饱水状态的现场直剪试验.结果显示,剪应力-剪切位移曲线饱水前、后均呈现出微弱的峰值,整体均表现为塑性破坏特征,饱水前、后发生屈服前的剪切位移分别为5 mm和10 mm以内.在强度参数上,两类夹层饱水前、后峰值强度内摩擦系数降低幅度一般在8%～10%,残余强度一般降低5%以内.表明以粗粒土为代表的软弱层带由于细粒(＜0.075 mm)物质少,细粒起不到包裹粗颗粒而作为润滑作用,同时因围压效应,饱水对其强度参数的影响有限,因此不同含水状态对该类软弱层带内摩擦角和内聚力均无显著影响,其强度参数主要还是取决于夹层本身的颗粒成分.     

缓倾角红层开挖路堑边坡支护设计中支护力计算

分析了四川盆地缓倾角红层地质结构特征,将下覆泥岩风化形成凹岩腔后的砂岩视为悬臂岩梁,提出了一种计算泥岩风化凹进极限深度及在设计支撑柱时计算支护力的计算方法,并给出一个计算示例。     

基于多源数据的广佛都市区城市引力结构特征分析

利用夜间灯光遥感数据和POI数据,采用断裂点分析法得出城市实体地域的范围大小。在此基础上引入交通便利系数和相对引力常量修正引力模型,分析广佛都市区内部各个城市实体地域间的引力强度和方向。结果表明：1）广佛都市区形成了以核心区为中心的“7+1”城镇体系结构;2）“七边形”正向城市体系结构围绕核心区域生成,“六边形”负向城市体系结构围绕西南区域生成,“西强东弱”格局明显;3）城市三角结构是广佛城市引力结构的基本单元,发展较好的城市组团为“核心区—顺德—南沙”“核心区—顺德—高明”“核心区—三水—花都”“核心区—花都—从化”,而“核心区—增城—南沙”和“核心区—高明—三水”组团则发展动能不足;4）广佛都市区引力势能大小及结构稳定与城市经济职能强度正相关。     

金龙山地区斜坡滑动优势面分析

据优势面分析原理和方法,对金龙山地区斜坡各种结构面所作的优势面分析结果显示:浅层强风化岩体中顺坡向剪切裂隙,是控制浅层顺层滑坡发生发展的滑动优势面;深层弱风化岩体中粘土岩风化软弱夹层、斜坡上段拉张裂隙与斜坡下段顺坡向剪切裂隙三者相组合,是控制深层顺层滑坡发生的滑动优势面。当地受滑动优势面控制的滑坡变形破坏模式有:浅层为蠕滑—拉裂,深层为滑移—弯曲。     

顺层岩质边坡顺层滑动岩体范围分析

顺层滑移-拉裂是顺层岩质边坡中常见的一种破坏模式,顺层滑动岩体范围大小是该类边坡稳定性分析及其加固支挡结构设计的基础,是设计人员最关心的问题。考虑边坡开挖卸荷效应对边坡岩体力学参数的影响,建立了顺层岩质边坡顺层滑动岩体范围的计算式,利用重庆至怀化铁路沿线顺层岩质路堑边坡失稳破坏的调查资料进行对比分析,结果吻合较好。     

Rock Strength and Development of Glacial Valley Morphology in the Scottish Highlands and Northwest Iceland

Using data from the Scottish Highlands and northwest Iceland, the present study indicates that bedrock strength properties are an important control on the morphology of glacial valleys. Results indicate that on closely jointed metasedimentary bedrock of low rock mass strength, broad U‐shaped valleys are developed, whilst steeper sided, narrower cross‐profiles have been developed on igneous bedrock of high rock mass strength. Findings suggest it is the interplay of the mass strength of the subglacial bedrock and the dynamic properties of the eroding glacier that control valley morphological development. The implication is that realistic models of topographic development beneath ice sheets need to consider the rock mass strength properties of the eroded bedrock as well as the glaciological variables.     

羌塘盆地玛曲地区膏岩盖层测井评价

为定量评价羌塘盆地玛曲地区膏岩盖层的封闭质量,基于羌资-16井实际钻遇的一套巨厚膏岩地层,根据膏岩与其它岩石的测井响应特征不同,有效地划分出膏岩地层的深度、厚度。选取厚度、孔隙度、渗透率和排替压力等4种关键参数评价膏岩盖层的封闭质量,并确立各参数的权值和计算方法。结果表明羌资-16井雀莫错组膏岩厚度大,孔隙度、渗透率极低,排替压力高,达到优质盖层标准。利用测井方法评价羌塘盆地玛曲地区膏岩盖层的封隔能力,为该区油气成藏机理研究提供了重要的依据。     

库车盆地古近纪—新近纪蒸发岩沉积演化特征及其资源效应初步探讨

库车盆地古近纪—新近纪时期具有巨厚的蒸发岩沉积,古近纪时期岩盐沉积的最大厚度达1 447.5 m,新近纪时期岩盐沉积的厚度有所减小,岩盐层最大厚度402 m。库车盆地在古近纪—新近纪时期沉积沉降中心也有所改变,从盆地西部的拜城凹陷转移到东部的康村—阳霞地区。库车盆地东西部蒸发岩岩体特征的差异,对此地区油气藏规模造成一定影响。初步判断库车盆地西部蒸发岩有可能比东部蒸发岩盐下形成的油气藏量较大。盆地中蒸发岩沉积中心的迁移对钾盐沉积也有重要影响。     

Influence of rock strength on the valley morphometry of Big Creek, central Idaho, USA

Analysis of valley morphometry and bedrock strength along Big Creek, central Idaho, shows that valley floor width is strongly controlled by bedrock. We performed statistical analysis of Schmidt hammer rock strength as a function of lithology and aspect and of valley morphometry as a function of rock strength. Rock strength is significantly greater on the south side of the valley and in Eocene granodiorites. Rock strength is weakest in Eocene volcanic tuffs. Valley floor width depends negatively on weakest valley-side rock strength, and hillslope gradient on the north side of the valley depends positively on rock strength. Stream gradient does not depend on rock strength. Valley floor width appears to be controlled by bedrock strength on the weaker side of the valley, which was generally the north (south-facing) side. We speculate that a higher degree of weathering via freeze–thaw cycles contributes to lower strength on the north side. The positive dependence of hillslope gradient on rock strength on the north side provides evidence that differential weathering across lithologies determines the gradient that can be maintained as lateral migration of the stream erodes valley walls. These results suggest that in situ rock strength exerts strong influences on some measures of valley morphometry by modulating hillslope mass wasting processes and limiting lateral erosion.     

川藏公路拉月滑坡的块状破坏特征

拉月滑坡位于东久河左岸，为典型的高位岩质滑坡。1967—08—29拉月一带山体突然发生特大型滑坡，体积超过千万立方米，是川藏公路线上著名的“拉月大塌方”灾害。文章应用块状岩体稳定性分析方法，对同结构岩石块体相互嵌合、形成具不同稳定状况的的岩体结构、控制了滑坡的发生的特点进行了分析，证明该方法判别岩质滑坡的稳定性是非常有效的。岩质滑坡在西藏与西南地区都十分普遍，因此，通过对拉月滑坡块状破坏过程的分析，对其它岩质滑坡的稳定性判别具有很好的借鉴作用。     

Thermal Regime of Rock and its Relation to Snow Cover in Steep Alpine Rock Walls: Gemsstock,Central Swiss Alps

Snow cover influences the thermal regime and stability of frozen rock walls. In this study, we investigate and model the impact of the spatially variable snow cover on the thermal regime of steep permafrost rock walls. This is necessary for a more detailed understanding of the thermal and mechanical processes causing changes in rock temperature and in the ice and water contents of frozen rock, which possibly lead to rock wall instability. To assess the temporal and spatial evolution and influence of the snow, detailed measurements have been carried out at two selected points in steep north‐ and south‐facing rock walls since 2012. In parallel, the one‐dimensional energy balance model SNOWPACK is used to simulate the effects of snow cover on the thermal regime of the rock walls. For this, a multi‐method approach with high temporal resolution is applied, combining meteorological, borehole rock temperature and terrain parameter measurements. To validate the results obtained for the ground thermal regime and the seasonally varying snowpack, the model output is compared with near‐surface rock temperature measurements and remote snow cover observations. No decrease of snow depth at slope angles up to 70° was observed in rough terrain due to micro‐topographic structures. Strong contrasts in rock temperatures between north‐ and south‐facing slopes are due to differences in solar radiation, slope angle and the timing and depth of the snow cover. SNOWPACK proved to be useful for modelling snow cover–rock interactions in smooth, homogenous rock slopes.     

Superposed deformation in turbidites and syn-sedimentary slides of the tectonically active Miocene Waitemata Basin, northern New Zealand

The Miocene Waitemata Basin was deposited on a moving base provided by the Northland Allochthon, which was emplaced in the Late Oligocene, as a new convergent plate boundary was established in northern New Zealand. The basin experienced complex interaction between tectonic and gravity‐driven shallow deformation. Spectacular examples of the resulting structures exposed on eastern Whangaparaoa Peninsula 50 km north of Auckland provide a world‐class example of weak rock deformation, the neglected domain between soft‐sediment and hard rock deformation. Quartz‐poor turbidite sequences display a protracted sequence of deformations: D1, synsedimentary slumping; D2, large scale deeper‐seated sliding and extensional low‐angle shearing, associated with generation of boudinage and broken formation; D3, thrusting and folding, indicating transport mostly to the SE; D4, thrusting and folding in the opposite direction; D5, further folding, including sinistral shear; D6, steep faults. The deformation sequence suggests continuous or intermittent southeastward transport of units with increasing sedimentary and structural burial. By phase D3, the rocks had passed from the soft‐sediment state to low levels of consolidation. However, with a compressive strength of ～5 MPa they are weak rocks even today. Such weak‐rock deformation must be important in other sedimentary basins, especially those associated with active convergent plate boundaries and with immature source areas for their sediments.