Deep-water Fan Systems and Petroleum Resources on the Northern Slope of the South China Sea

The shallow shelf delta/strand arenaceous-pelitic deposit region in the north of the Pearl River mouth basin, sitting on the northern continental shelf of the South China Sea, has already become an important oil production base in China. Recent researched has revealed that a great deal of deep-water fans of great petroleum potentiality exist on the Baiyun deep-water slope below the big paleo Pearl River and its large delta. Based on a mass of exploration wells and 2-D seismic data of the shallow shelf region, a interpretation of sequence stratigraphy confirmed the existence of deep-water fans. The cyclic falling of sea level, abundant detrital matter from the paleo Pearl River and the persistent geothermal subsidence in the Baiyun sag are the three prerequisites for the formation and development of deep-water fans. There are many in common between the deep-water shelf depositional system of the northern South China Sea and the exploration hotspots region on the two banks of the Atlantic. For example, both are located on passive continent margins, and persistent secular thermal subsidence and large paleo rivers have supplied abundant material sources and organic matter. More recently, the discovery of the big gas pool on the northern slope of the Baiyun sag confirms that the Lower Tertiary lacustrine facies in the Baiyun sag has a great potentiality of source rocks. The fans overlying the Lower Tertiary source rocks should become the main exploration areas for oil and gas resources.

Deep-seated large-scale toppling failure in metamorphic rocks：a case study of the Erguxi slope in southwest China

Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope located in southwest China,which affected a large area and damaged critical transportation infrastructure with the volume of the deforming rock mass exceeding 24×10~6 m^3.It poses significant risks to the downstream Shiziping Hydropower Station by damming the Zagunao River.Field investigation and monitoring results indicate that the deformation of the Erguxi slope is in the advanced stage of deep-seated toppling process,with the formation of a disturbed belt but no identifiable master failure surface.It was postulated that the alternating tensile and shear strength associated with the hard/soft laminated rock strata of metasandstone and phyllite layers preclude the development of either a tensile or shear failure surface,which resulted in the continuous deformation and displacement without a catastrophic mass movement.The slope movement is in close association with the unfavorable geological conditions of the study area in addition to the construction of transportation infrastructure and the increase of the reservoir level.On the basis of the mechanism and intensity of the ongoing toppling deformation,a qualitative grading system was proposed to describe the toppling process and toevaluate the slope stability.This paper summarized the field observation and monitoring data on the toppling deformation for better characterizing its effect on the stability of the Erguxi slope.The qualitative grading system intends to provide a basis for quantitative study of large-scale deep-seated toppling process in metamorphic rocks.

Study on determination of the stable slope configuration for deep open pit mine

The space effects of deep pit slope are analyzed by an elastic mechanics principle. The interaction among the critical slide angle, the friction coefficient, the cohesion, and the horizontal radius of the deep pits is derived in this paper. It indicates that the deeper the pit is excavated, the greater the critical slide angle is. Both the theory for reducing stripping waste rock in deep pit and the approach to determining the configuration of the stable slope are developed from the interaction. The theory in this paper comprises the preceding principles of stability analysis of slopes and is suitable for analyzing that of deep pit.

The Relationship between Tectonic Subsidence and BSR of Upper Neogene in the Deep-Water Area of the Northern Continental Slope, South China Sea

BSR （Bottom Simulating Reflector） occurs widely in the strata since the late Miocene in the deep-water area of the northern continental slope of South China Sea （SCS）. It is an important seismic reference mark which identifies the gas hydrate and its distribution influenced by the tectonic movements. Single-point basin modeling was conducted using 473 points in the study area. To discuss the relationships between the tectonic subsidence and BSR, the volume and rate of tectonic subsidence in each geological time have been simulated. The results show that there are three tectonic accelerate subsidence processes in the study area since the late Miocene, especially since 1.8Ma the tectonic subsidence accelerates more apparently. Since the Late Miocene to Pleistocene, the rate of tectonic subsidence in deep-water underwent a transformation from weak to strong. The ratio of tectonic subsidence to the total subsidence was relatively high （65-70%）. Through the superposition of the BSR developed areas and the contours of tectonic subsidence in this area, it was discovered that more than 80% of BSR tend to be distributed at the slope break or depression-uplift structural transfer zone and the average tectonic subsidence rate ranges from 70 m/Ma to 125 m/Ma.

Study on the Submarine Slope Stability of the Deep Channel in the Caofeidian Harbor

Objective The greatest advantage of the Caofeidian Harbor is its deep channel facing the Bohai Bay. The deep channel is a natural port hub for shipping of the Caofeidian Habor. The construction of the Caofeidian Harbor has impacted the hydrodynamic environment and the sediments movement, which has attracted much attention about the geomorphic evolution, slope stability and the evolution trend after submarine slope destruction. Insight from this study might be significant for the future development of the Caofeidian Habor, including planning, operation and maintenance.

Main Detrainment Height of Deep Convection Systems over the Tibetan Plateau and Its Southern Slope

Deep convection systems (DCSs) can rapidly lift water vapor and other pollutants from the lower troposphere to the upper troposphere and lower stratosphere. The main detrainment height determines the level to which the air parcel is lifted. We analyzed the main detrainment height over the Tibetan Plateau and its southern slope based on the CloudSat Cloud Profiling Radar 2B_GEOPROF dataset and the Aura Microwave Limb Sounder Level 2 cloud ice product onboard the Atrain constellation of Earth-observing satellites. It was found that the DCSs over the Tibetan Plateau and its southern slope have a higher main detrainment height (about 10-16 km) than other regions in the same latitude. The mean main detrainment heights are 12.9 and 13.3 km over the Tibetan Plateau and its southern slope, respectively. The cloud ice water path decreases by 16.8% after excluding the influences of DCSs, and the height with the maximum increase in cloud ice water content is located at 178 hPa (about 13 km). The main detrainment height and outflow horizontal range are higher and larger over the central and eastern Tibetan Plateau, the west of the southern slope, and the southeastern edge of the Tibetan Plateau than that over the northwestern Tibetan Plateau. The main detrainment height and outflow horizontal range are lower and broader at nighttime than during daytime.

供水工程新近系红层区斜坡深层变形破坏模式分析

针对新近系红层区斜坡变形破坏模式认识不足的问题,通过对以往工程区斜坡破坏现象的调查分析,寻找已有深层破坏形成的滑坡体,反分析滑坡体破坏前原始斜坡地质结构模型,并建立典型斜坡深层破坏模式,根据变形体主要工程地质条件,建立红层斜坡变形体的三维数值模型,分析其在天然、地震及降雨等条件下的稳定性。结果表明,通过建立的新近系地层不同岩段区斜坡深层破坏模式,识别出新近系地层区供水工程20#支线沿线有一个大型深层破坏斜坡变形体。该斜坡变形体在降雨条件下的稳定性较差。

顺层深路堑边坡滑带土强度特性和基底预留厚度预警分析

含软弱夹层的顺层深路堑边坡在边坡工程中普遍存在,滑带土强度和基底预留厚度(开挖边坡基底到软弱夹层的距离)是影响其稳定性的2个关键性因素。以杨宣(杨柳-宣城)高速K42路堑边坡为例,分析了边坡变形演化过程和基底隆起变形特征,通过适合研究大剪切位移下土体抗剪强度的环剪试验揭示了边坡深部滑带土的特性,应用滑带土的饱和残余强度参数进行了边坡开挖基底预留厚度分析。结果表明:K42滑带土有明显的应变软化特性,且法向应力越小滑带土应变软化特性表现越明显;由峰值抗剪强度到残余抗剪强度,黏聚力和内摩擦角均表现出衰减效应,且黏聚力衰减程度大于内摩擦角;滑带土残余抗剪强度参数中的残余黏聚力随剪切速率的变化很小,而残余内摩擦角和剪切速率呈对数函数φ=0.1303ln v+7.3197关系变化,当剪切速率<2 mm/min时,滑带土残余抗剪强度参数对剪切速率较为敏感,反之敏感性较差;最后,依据边坡不同临界状态的回归方程h_(1)、h_(2)、h_(3)将不同坡率下的基底预留厚度分成A(失稳)、B(欠稳定)、C(基本稳定)以及D(稳定)4个区,并且在此基础上建立了基底预留厚度判据和边坡开挖基底预留厚度预警模型。

库水作用下深层倾倒变形体的失稳软化机制研究

在高山峡谷地貌和复杂脆弱的地质环境下,库岸边坡深层倾倒变形破坏现象成为了威胁水电工程安全运转的重大工程地质问题。近些年来随着越来越多大型、巨型水电工程建设与蓄水运行,深层倾倒变形体破坏问题逐渐凸显。这些深层倾倒变形体具有长期饱水(王雅雯,2016)、发育岩性为于遇水软化作用明显的软岩之中、滑坡演化时间长以及变形破坏模式为牵引式破坏(张成强,2018)等特点。综合以上特点.

深度置信网络算法在公路边坡工程安全评价中的运用

针对传统边坡工程安全评价方法无法对边坡稳定性进行符合实际情况下工程安全评价的问题,提出一种基于深度置信网络(Deep Belief Networks,DBN)算法的公路边坡工程安全评价方法。首先,使用MATLAB建立模型;然后,对基于DBN算法的边坡稳定性安全评价方法进行研究;最后,使用DBN算法在莆炎高速公路项目中进行公路边坡工程安全评价。结果显示:(1)与反向传播(Back Propagation,BP)神经网络相比,DBN模型得到的预测值误差更小,精度更高,计算复杂度更低、可扩展性更强;(2)在实际工程中,DBN算法能够有效地对众多非线性因素共同作用下的公路边坡进行符合实际的安全评价。

冷竹关沟高陡斜坡地震动响应特征

四川省泸定县冷竹关沟两岸属于高陡斜坡,距2022年5月20日汉源M_(S)4.8地震震中52 km。基于冷竹关沟监测剖面上安置的4台强震仪对汉源M_(S)4.8地震的监测数据,分析了高陡斜坡上的地震波响应规律,并与前人研究成果对比,结果显示:(1)斜坡对此次地震的地震波放大效应在水平南北向最为显著,右岸半岛状山梁处的放大作用强于左岸浑厚山体,且随着高程的增加场地的放大作用逐渐增大;(2)斜坡右岸的地震动卓越频率为2—6 Hz,左岸主要分布在7—13 Hz,冷竹关沟高陡斜坡的地震动卓越频率在半岛状山梁部位以特低频为主,在浑厚山体斜坡以中低频为主,在未来可能发生的地震中,斜坡更容易与卓越频率在此范围内的地震动记录发生共振作用,以致坡体地震动响应强烈;(3)冷竹关沟高陡斜坡存在地震波背坡效应,同时该处斜坡对地震波的放大效应还受到微地形的控制,地震波在右岸坡顶凸起地形处能量最为强烈,右岸斜坡坡顶在地震波经过时更容易发生崩塌等次生灾害。

川东红星地区中上二叠统页岩气勘探成果及方向展望

基于构造、岩心、测井等资料,采用电镜扫描、低温N_(2)吸附实验、高压压汞实验、盆地模拟等手段,系统分析了川东红星地区中上二叠统页岩的沉积演化、储层特征及页岩气富集模式,明确了勘探有利区,总结了勘探成果及意义。研究结果表明:(1)红星地区中上二叠统的沉积演化表现为:栖霞组—茅口组三段为开阔台地相;茅四段底部为台地-陆棚相,相带变化快,茅四段顶部为斜坡-陆棚相,地层被剥蚀、南厚北薄;吴家坪组一段(吴一段)底部为海陆过渡滨岸沼泽-潟湖相,吴一段顶部为台地-斜坡-陆棚相,斜坡-陆棚相带分布范围小、相变快;吴二段为斜坡-陆棚相沉积,从早至晚依次受控于古气候、火山活动和古气候、火山活动,沉积中—晚期古生产力较高,TOC均值大于8.00%。(2)研究区茅四段及吴二段陆棚相区发育2套优质页岩,具有“高有机碳-高灰质”的特征,富有机质页岩厚度分别为19 m和25 m,孔隙类型以有机孔为主,结构以微孔和介孔为主;富碳凝灰岩薄夹层混合质页岩岩相、高碳凝灰岩薄夹层硅质页岩为优质岩相,孔隙度分别为6.27%和6.43%,TOC值分别为10.11%和9.35%,含气饱和度分别为92.59%和91.81%,脆性指数分别为55.24%和61.19%,是地质和工程的双“甜点”段。(3)研究区二叠系广泛发育的层状藻为主要有机质来源;在侏罗纪主排烃期,其构造稳定、二叠系烃源岩排烃较少,中侏罗纪—早白垩纪早期为主生气期,构造活动较弱,页岩气的保存条件好,现今已完成生气过程,处于成熟—过成熟阶段,Ro值约2.1%,勘探潜力巨大。(4)建南、龙驹坝、三星区块为有利勘探区,其中建南区块潜力最大;茅四段(3)小层及吴二段(3)小层为优质层系的靶窗层段。

深水斜坡沉积特征与控制因素——以澳大利亚柔布克盆地为例

深水斜坡沉积规律对深水油气勘探开发以及深水地质灾害防护具有重要的研究意义。为揭示澳大利亚柔布克盆地新近纪深水斜坡沉积特征与控制因素,利用高分辨率二维地震资料,划分了斜坡沉积地层层序,在地震剖面上识别出7个三级层序界面和6个地震层序。研究结果表明:研究区新近纪主要形成了进积型、加积-进积混合型和退积型沉积层序;柔布克盆地深水区发育前积型碳酸盐岩、硅质碎屑三角洲和滑塌3种斜坡沉积;研究区深水斜坡沉积受多种因素共同控制,中渐新世—晚中新世,斜坡沉积主要受相对海平面升降、古气候变化和物源供给的控制,而晚中新世之后,向北漂移的澳大利亚板块与班达岛弧发生碰撞,深水斜坡沉积主要受构造活动的控制。

一种基于深度学习与图像局部特征提取的边坡异常监测技术

为提升边坡险情的监测能力,本文提出了一种基于深度学习与图像局部特征提取的边坡异常监测技术。该技术通过提取边坡自然特征物的二维坐标构成目标三角网络,以三角网络的变化区域圈定边坡险情范围,并提取变化范围内的同名特征点,以同名特征点的位移情况对边坡的变化进行描述。首先,拍摄边坡发生险情前后的图像,利用目标检测模型YOLOv5识别边坡自然特征物,利用语义分割模型DeepLabV3+对提取的自然特征物进行语义分割得到其二值化区域,提取区域中心得到二维坐标,以所有自然特征物的二维坐标点阵构建目标三角网络,并以三角网络变化圈定边坡的变化范围。然后,利用图像特征提取技术,提取变化范围之内的同名特征点,并统计其位移距离与方向,以此反馈边坡的变化情况。最后,设计了试验验证该方法的稳定性与可靠性,并在真实的边坡验证了方法的实用性。试验结果表明,该技术能够对边坡的变化进行有效监测,是边坡监测工程中的一种可行技术。

基于FLAC^(3D)的露天矿山深部开采边坡稳定性研究

为研究复杂地质条件露天矿山深部开采整体边坡稳定性问题,根据现场钻孔数据和地质调查,依次通过犀牛软件建立复杂三维地质体模型、griddle软件对模型进行网格划分、导入FLAC^(3D)三维数值分析软件进行计算,最终得到矿山露天边坡的应力大小(最大拉应力为0.3 MPa)、位移量(最大位移量13 cm)、塑性区分布、剪应变增量,最小安全系数值等结果。通过对三维软件计算结果的逐个分析,得出该露天矿山深部开采边坡的稳定情况,Ⅰ区边坡稳定性略差,Ⅲ区的边坡稳定性最差,Ⅳ、Ⅴ区边坡稳定性好,该结论为矿山深部开采边坡监测划分重点区域和矿山安全生产提供理论依据和技术保障。

基于沉积学原理的被动陆缘陆坡古地貌恢复方法

深入了解被动陆缘陆坡古地貌如何控制深水重力流储层的形成与分布对深水油气勘探意义重大。在少井探区,基于三维地震的地层厚度印模法在古地貌研究中应用广泛,但是,陆坡区容易因沉积物供给不足而处于“半饥饿欠补偿”状态和陆坡地形坡度的存在会影响该方法的适用性和准确性,对沉积体系和油气储层的分布特征分析产生不利影响。为此,根据沉积型陆坡的特点,对地层厚度印模法进行了两方面的补充与改进:其一,通过三维地震资料的分析明确目的层陆坡补偿状态,讨论了地层厚度印模法的适用性;其二,根据研究区陆坡演化过程,以沉积物体积等分方式求取目的层段各层序对应的潜在坡度趋势,基于此实现古陆坡地形坡度校正。利用改进后的方法对非洲西部尼日尔三角洲盆地下陆坡古地貌进行恢复的结果与研究区现有构造演化认识高度一致,符合“构造活动主导地貌特征”这一普遍认识。另外,地震属性刻画出的深水沉积体系分布特征与古地貌恢复结果间存在良好的耦合关系。应用实例证明了改进方法的科学性和研究区古地貌恢复结果的客观性。

软弱地基排土场稳定性分析及控制

针对某坡脚为深厚软弱层地基排土场的稳定性,采用多种极限平衡法分别计算排土场在正常工况、降雨工况、地震工况下的安全系数。根据计算结果,对比规范要求,进行排土场断面优化设计。提出采用清理基底软土层、降低边坡角、堆填块石压坡脚以及其他防治措施,从源头上提出解决排土场重大安全风险隐患的系统防范机制,实现工程本质安全管理。研究成果为深厚软弱层地基排土场边坡设计及治理提供了理论支持和参考。

基于图深度学习与北斗监测的边坡位移预测研究

位移预测是边坡地质灾害监测预警的关键,本文以温州绕城高速公路边坡为例,提出了一种新的基于图深度学习与北斗监测的边坡多因子位移预测方法。首先基于北斗高精度监测点位的空间位置对整体监测体系的图结构进行建模,构建图节点之间的邻接矩阵。再对北斗高精度位移、降雨量、地下水位与土壤含水率多因子监测数据进行去粗差、插值与归一化等时序数据处理,并进行时空相关性分析,结果表明位移主要受连续两个月的降雨量、三级边坡的地下水位与土壤含水率的影响。将最先进的基于图深度学习的GTS(Graph for Time Series)预测模型引入边坡位移预测中,提出适用于北斗高精度边坡变形监测的GTS-BDS位移预测模型。当预测时长为1 h时,其均方根误差(RMSE)、平均绝对误差(MAE)与平均绝对百分比误差(MAPE)指标评价分别达到0.301、0.154与3.5%,均优于LSTM与T-GCN等模型。本文所提出的位移预测方法充分利用了北斗高精度及其他传感器监测点位之间的空间拓扑与监测数据的时序特征,从整体监测体系的角度提升边坡位移预测的准确率与可靠性,在边坡安全预警中具有良好的应用前景。

基于三维有限元的DCM平面布置对边坡稳定的影响

在应用于边坡稳定问题时,DCM(深层水泥搅拌桩)的平面布置形式直接关系到其受力的合理性,进而影响边坡的稳定和安全。针对当前工程实践中采用不同DCM平面布置形式解决边坡稳定问题时,其受力机理仍存在一定程度的认识不足,基于三维有限元方法,结合不同的DCM平面布置形式(桩式、横墙壁式、纵墙壁式、格栅式),对加固后边坡从整体稳定、位移和应力等方面进行分析,探讨采用不同DCM平面布置形式加固边坡后的位移和应力分布规律及特点。研究表明:纵墙壁式和格栅式布置相对于桩式布置,边坡整体稳定安全系数显著提高,位移和应力明显减小且分布更为合理,其中纵墙壁式布置优势最为明显。

露天矿边坡裂隙智能识别与信息解算

节理裂隙是影响露天矿边坡稳定性的重要因素之一,随着图像处理技术以及机器视觉技术的发展,采用智能算法进行识别已成为热点.为快速获取节理裂隙几何信息,通过ResNet系列算法对U-net的骨架构网络进行改进,提出了一种露天矿边坡裂隙识别及几何参数解译方法.利用无人机综合考虑视角、距离、重叠率以及飞行速度等因素对露天矿边坡裂隙航拍获取高清图像,使用全局阈值分割技术进行预处理,并运用随机旋转、随机亮度及对比度调整等方式进行数据增广形成裂隙图像数据集;采用残差网络(ResNet)对U-Net网络的骨架构网络进行改进,提出基于改进U-net网络的边坡裂隙识别模型,基于像素二分类问题采用准确率(Accuracy)、交并比(IoU)和F1分数(F1 Score)作为评价指标,结合裂隙图像数据集对提出模型进行训练和评估,输出裂隙二值图,并与传统裂隙识别方法识别结果进行对比;对裂隙二值图进行裂隙几何参数信息解算,获得裂隙长度、宽度统计分布规律和参数.结果表明:ResNet模型对U-net模型改进可以提高模型的评价指标,随着网络层数加深,评价指标有先增高,后趋于稳定的趋势,在网络层次达到101时评价指标达到最优,Res101-Unet模型的Accuracy、IoU、F1 Score分别为95.12%、60.13%、79.53%,对于简单和复杂裂隙的识别完整度都有提升;利用训练好的Res101-Unet模型对目标边坡上的裂隙进行识别,所得裂隙数量与现场测线方式所得结果一致,证明本模型识别结果与工程实际相符.