Is the Cape Stone Forest in Shantou City formed by wave erosion? A comparison of the pedestal rocks on the coasts and the mountains of Queshi in eastern Guangdong, China

Cape Stone Forest is a group of granite rock pillars(pedestal rocks) towering over Shilin Lake, on the southern shore of Shantou Bay in eastern Guangdong, China. The rock pillars were previously identified as sea stacks because they have marine notch-like concave sidewalls at their base, and more importantly, the lake is immediately adjacent to the bay, which is exposed to the open sea. However, rock pillars similar in shape and size can also be found at the top of Queshi Mountain, which is only about 300 meters northwest of the lake and about 85 meters above sea level. Therefore, the marine origin of Cape Stone Forest is seriously questioned. In this study, 3D imagery and drone technology were used to collect data in the investigations without direct manual measurements in the water or on the mountain. It shows that the concave sidewalls of the rock pillars in the lake and on the mountains occur at different heights and are exposed to different directions, while a natural sea stack on Mayu Island at the mouth of Shantou Bay has a horizontal notch parallel to the sea level, although the granite rock of the sea stack is the same as that of the lake and the mountains. The eastern side of the island, where the sea stack is located, is exposed to the open sea but blocks large waves for the rock pillars in the lake. Therefore, the origin of Cape Stone Forest cannot be explained by wave-based mechanisms. The only satisfactory explanation that takes into account all the field evidence is that the narrow rock pillars of the lake and mountain were formed by chemical weathering that penetrated closely the spaced joints of the granite rock, and the notch-like concave sidewalls were formed by more effective chemical weathering at the base of the pillars.

Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments

Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes （SS） with different sand cover patterns （including length and thickness） and uncovered loess slopes （LS） to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.

A review of the research on complex erosion by wind and water

Complex erosion by wind and water, which is also called aeolian-fluvial interactions, is an important erosion process and landscape in arid and semiarid regions. The effectiveness of links between wind and water process, spatial environmental transitions and temporal environmental change are the three main driving forces determining the geomorphologic significance of aeolian-fluvial interactions. As a complex interrelating and intercoupling system, complex erosion by wind and water has spatial- temporal variation features. The process of complex erosion by wind and water can be divided into palaeoenvironmental process and contemporary process. Early work in drylands has often been attributed to one of two schools advocating either an ＇aeolianist＇ or a ＇fluvialist＇ perspective, so it was not until the 1930s that the research on complex erosion by wind and water had been conducted. There are two obstacles restricting the research of complex erosion by wind and water. Firstly, how to transform in different temporal and spatial scales is still unsettled; and secondly, the research methodology is still immature. In the future, the mechanism and control of erosion, the complex soil erodibility in wind and water erosion will be the focus of research on complex erosion by wind and water.

Investigation of long-wavelength elastic wave propagation through wet bentonite-filled rock joints

The saturation of the compacted bentonite buffer in the deep geological repository can cause bentonite swelling,intrusion into rock fractures,and erosion.Inevitably,erosion and subsequent bentonite mass loss due to groundwater inflow can aggravate the overall integrity of the engineered barrier system.Therefore,the coupled hydro-mechanical interaction between the buffer and rock during groundwater inflow and bentonite intrusion should be evaluated to guarantee the long-term safety of deep geological disposal.This study investigated the effect of bentonite erosion and intrusion on the elastic wave propagation characteristics in jointed rocks using a quasi-static resonant column test.Jointed rock specimens with different joint conditions(i.e.joint surface saturation and bentonite filling)were prepared using granite rock discs sampled from the Korea Underground Research Tunnel(KURT)and Gyeongju bentonite.The long-wavelength longitudinal and shear wave velocities were measured under different normal stress levels.A Hertzian-type power model was used to fit the wave velocities,and the relationship between the two fitted parameters provided the trend of joint conditions.Numerical simulations using three-dimensional distinct element code(3DEC)were conducted to better understand how the long-wavelength wave propagates through wet bentonite-filled rock joints.

发生骨侵蚀的早期银屑病关节炎患者的临床特征

目的:探讨早期PsA发生骨侵蚀患者的临床特征及相关因素。方法:选取2018年1月至2023年1月住院治疗的早期PsA(关节炎病程≤1年)患者50例,采用彩色多普勒超声仪对患者外周关节进行超声检查,分析发生骨侵蚀的部位及特征,根据超声下有无骨侵蚀分为骨侵蚀组及无骨侵蚀组,分析两组间年龄、性别、病程、血沉、C反应蛋白等临床和实验室参数以及超声影像等的差异。结果:50例PsA患者中23例(46.00%)存在骨侵蚀,27例(54.00%)无骨侵蚀,骨侵蚀组较无骨侵蚀组受累外周关节数更多(P<0.05)。骨侵蚀组手、足关节受累及附着点炎发生率均明显高于无骨侵蚀组(P<0.05)。两组间在年龄、性别、病程、皮疹是否先发、中轴关节是否受累、HLA-B27的阳性率及炎性指标等方面均无统计学差异(P>0.05)。手、足关节受累、附着点炎、受累外周关节数与骨侵蚀呈正相关。结论:骨侵蚀在早期PsA患者较为多见,最常发生于手、足关节,并与附着点炎及受累外周关节数密切相关。

Interfacial microstructure and properties of YG11C/42CrMo joint brazed with BCu64MnNi filler metal

Brazing hard alloy to high strength steel, incomplete atomic diffusion and excessive brittle reaction product precipitation at the faying interface are usually suffered because of incomplete understanding the process of the initial interface disappearing and diffusion layer forming and evolving. In this paper , hard alloy YG11C （ WC-11wt. %Co） and high strength steel 42CrMo were picked up as base metals and BCu64MnNi as filler metal to clarify the interfacial microstrncture evolution. The process parameters of dwell time were set as 30 s, 60 s, 120 s, and 300 s and braze temperature were set as 950 ℃, 970 ℃, 990 ℃, 1 010 ℃, the effect of which on the evolution of interfacial microstructure, tensile strength, integrated with fracture morphology analysis, were conducted. The results showed that increasing brazing temperature from 950 ℃ to 970 ℃, no signifwant difference existed in the joint interface, whereas brazed at 990 ℃, the binder phase erosion occurred, i. e. the liquid filler metal etched into Co binder phase of WC-Co base metal, which caused WC particles debonding from the base metal surface and formed an micro-anisotropic zone.. Increase temperature to 1 010 ℃, severe binder erosion happened so as to micropores appear. Through the parameters optimization, the tensile strength can reach to the maximum 589 MPa at temperature of 970 ℃. The dwell time showed similar effect on tensile strength because longer dwell time also caused erosion and porosity owing to long-time diffusion and reaction.

蒸发塔挥发线腐蚀分析

某蒸发塔挥发线,运行期间多次发生腐蚀穿孔,采用碳纤维补强作为临时措施。在装置大修期间,开展设备的腐蚀调查,并截取有代表性的弯头、法兰短节开展腐蚀问题分析。采用现场腐蚀调查、宏观和微观腐蚀形貌观察、XRD成分分析、EDS能谱分析等方法开展分析测试,并针对焊缝进行了金相组织观察和硬度测试。分析结果表明,由于硫酸腐蚀与电偶腐蚀、缝隙腐蚀、冲刷腐蚀等的协同作用,在法兰面、焊缝、弯头等薄弱位置形成严重的局部腐蚀。建议加强内衬的质量控制,避免异金属连接,对弯头、焊缝等重点位置加强检测。

Cavitation erosion behavior of CLAM steel weld joint in liquid lead-bismuth eutectic alloy

The cavitation erosion of weld joint and base metal of China low activation martensitic（CLAM）steel in liquid lead-bismuth eutectic alloy（LBE）at 550°C was investigated to simulate the cavitation erosion of the first wall and the nuclear main pump impeller in the accelerator driven sub-critical system（ADS）.A suit of ultrasonic cavitation facility was self-designed to study the cavitation erosion.By studying the surface micro topography,roughness and mean pit depth of the tested specimens,it was found that some crater clusters and large scale cracks appeared on the tested specimen surface after the formation of numerous single craters,and the base metal exhibited much better cavitation erosion resistance than the weld bead due to the difference in their mechanical properties and microstructures.In addition,by comparing the results of static corrosion and cavitation erosion,it could be concluded that the cavitation erosion and the dissolution and oxidation corrosion in liquid LBE would accelerate mutually.

排砂管线弯接头的冲蚀机理研究

排砂管线是气体钻井中不可缺少的地面设备之一,在高压高产气井的钻井中存在安全隐患,常规情况下通常被人们忽略。排砂管线失效主要由高速气流中的固体颗粒冲蚀破坏,通常发生在弯接头部分。针对排砂管线弯接头的冲蚀失效情况,开展冲蚀破坏机理的理论研究和数学模型研究,对弯接头的冲蚀攻角、冲蚀函数、冲蚀颗粒形状系数以及固体颗粒的受力状况进行探讨。建立排砂管线弯接头的CFD有限元模型,可以任意改变弯接头的角度,定量地模拟不同工况下含有固相颗粒的多相流对弯接头的冲蚀速率和冲蚀机理,对排砂管线在气体极限流量100×104m3/d和50×104m3/d的工况下,对不同含砂量进行一系列的CFD仿真模拟,得出冲蚀速率随弯接头角度变化定量的关系曲线,为弯接头的结构优化设计提供理论依据。

气体携岩对钻杆接头冲蚀规律研究

针对气体钻井钻杆接头冲蚀严重易导致钻杆快速失效的问题,基于两相流计算流体动力学有限元法建立了气体携岩冲蚀18°斜坡钻杆的CFD仿真模型。根据此模型,系统地研究了钻杆居中、钻杆不同偏心程度、不同注气量以及不同钻速对岩屑颗粒冲蚀钻杆接头、岩屑颗粒运动轨迹和浓度分布以及环空气流速的影响。结果表明:(1)钻杆居中时,冲蚀速度对称分布,接头冲蚀比钻杆本体冲蚀严重,迎风坡面顶部附近出现最大冲蚀速度。同时,得到了接头最大冲蚀速度随岩屑质量流量及携岩速度的定量关系;(2)钻杆偏心时的最大冲蚀速度和接头宽流道环空一侧的冲蚀速度比钻杆居中时大,且偏心程度越高,接头环空窄流道一侧冲蚀区域越密集。钻杆偏心程度在30%～70%时,最大冲蚀速度由钻杆接头转移至钻杆本体。接头最大冲蚀速度分别在钻杆偏心0～30%、50%～70%和80%～90%时随携岩速度增加而增加,但在钻杆偏心30%～50%和70%～80%时最大冲蚀速度随接头环空宽流道岩屑浓度减小而减小。研究结果为预防钻杆接头冲蚀失效提供了理论依据,并在现场得到了应用。

黄土崩塌破坏模式及离散元数值模拟分析

黄土崩塌是黄土高原区最常见、致灾最为严重的一种地质灾害。首先,从黄土地形地貌、黄土类型及结构、黄土垂直节理、坡脚侵蚀、降雨、人类工程活动等方面分析了黄土崩塌的成因,认为黄土中的垂直节理和坡脚侵蚀作用是造成黄土崩塌的主要原因;其次,通过野外黄土崩塌变形破坏特征及地质现象分析,将黄土崩塌归纳为拉裂-坠落式、拉裂-倾倒式、拉裂-下挫式和拉裂-滑移式4种主要破坏机制,并概化出了各类破坏示意图;通过离散元数值模拟,对黑龙沟黄土崩塌的形成破坏过程进行了再现和分析,其破坏过程为侵蚀剥落-坡脚局部凹进-垂直节理张开-下挫解体-堆积坡脚。

膝关节类风湿关节炎滑膜切除术后远期观察

目的连续观察膝关节类风湿关节炎(RA)滑膜组织切除对改善关节损害及对生活质量的远期效果。方法1988-1997年中21例RA患者做24个膝关节滑膜切除。在术前、术后0.5年以及连续8年每年检查X光平片并用Larsen评分法评估骨破坏情况及健康评定问卷(HAQ)评分情况。结果滑膜切除术后关节损害均有不同程度改善,关节周围骨质疏松有明显好转。在手术0.5年开始Larsen评分下降,1年时获得最好效果并至少能持续5年,此后再度出现关节损害。HAQ评分在术后0.5年出现最好效果并至少维持2年,术后4年恢复至术前水平并逐步恶化。结论膝关节滑膜切除不仅能阻止局部病变的进展,而且有利于改善关节周围骨破坏,提高生活质量。但在术后远期,随着滑膜组织增生再度出现关节损害和生活质量下降。因此,从临床上证实RA滑膜组织参与关节周围骨破坏和全身疾病活动。

类风湿关节炎手腕部骨侵蚀的磁共振定量分析

目的:通过类风湿关节炎手腕部骨侵蚀MRI表现及临床指标对照研究,探讨两者在评价类风湿关节炎诊断及预后中的价值。方法:随机选取行手腕部MRI扫描的患者80例,患者均在1周内行相关实验室检查,其中符合类风湿诊断标准的入选为研究对象。采用OMERACT的RA评分系统为类风湿关节炎骨质破坏的评分标准,对磁共振图像进行分析及评分。分别按性别、年龄、病程、晨僵、类风湿因子(RF)、抗环瓜氨酸肽(抗CCP)、抗"O"(ASO)、C反应蛋白(CRP)、血沉(ESR)予以分组,使用Mann-Whitney方法分析各组间骨侵蚀的差异。结果:符合RA诊断标准的共54例,共发现238处骨质侵蚀,最多的1例累及13处骨质。腕部骨侵蚀最常累及三角骨(36/54),其次为头状骨(31/54);手部最常累及第三掌骨头(7/54),其次为第二掌骨头(6/54)。早期/中晚期RA组、CRP阳/阴性组、ESR阳/阴性组间骨侵蚀评分差异具有高度统计学意义(P<0.01)。抗CCP阳/阴性组间的骨侵蚀评分差异具有统计学意义(P<0.05)。性别、年龄、晨僵、RF、ASO的组间骨侵蚀评分差异无统计学意义(P>0.05)。结论:MRI可为骨侵蚀的诊断及评估预后提供最直观的依据,抗CCP抗体、CRP、ESR可在一定程度上提示骨侵蚀。

胶原诱导型关节炎大鼠的关节影像学特点

目的旨在分析CIA X线片四肢关节的破坏特点,揭示CIA大鼠关节破坏的规律,为规范评分方案提供依据。方法采用П型胶原和弗氏完全佐剂皮下注射清洁级Wistar大鼠,造模成功(每批10只,共3次)后第35天行全身X线钼靶照片,以正常组作为对照、每只大鼠评价96块骨破坏(erosion)和100个关节间隙(joint space narrowing,JSN);处死动物,取左前肢和右后肢近端第3足趾关节苏木素-伊红(HE)染色,评价中性粒细胞、淋巴细胞、浆细胞浸润、滑膜增生和软骨破坏的情况。结果造模成功后CIA大鼠关节出现明显的红肿,活动受限;HE病理显示,CIA关节存在明显的中性粒细胞、淋巴细胞和浆细胞浸润,滑膜增生,纤维组织增生,软骨破坏;X线片分析结果显示:①广泛性骨质疏松,边缘性骨质侵蚀,关节间隙狭窄或增宽,部分踝关节间隙消失,关节相互融合甚至骨性强直。②67%的骨出现erosion,JSN影响为78%,关节破坏以中、重度为主;③远端、近端趾间关节和踝关节发病率高,损害严重,掌趾关节发病率低,破坏较轻。④后肢关节破坏重于前肢(P<0.01),左右肢没有显著性差异(P>0.05)。结论①滑膜是CIA炎症反应启动的主要病灶,与骨交界的滑膜和血管翳造成了CIA的骨质破坏;②CIA影像学表现关节破坏严重,以远端、近端趾间关节和踝关节为主,这些关节可作为评价破坏程度的选择。本研究对于深入CIA关节破坏的病因病理和进一步规范X线片评分方案具有一定意义。

超声在鉴别类风湿性和痛风性跖趾关节炎骨质侵蚀中的应用

目的探讨超声在类风湿性关节炎与痛风性关节炎骨质侵蚀的诊断与鉴别诊断价值。方法回顾性分析本院43例类风湿性关节炎患者和52例痛风性关节炎患者的足部跖趾关节骨质侵蚀声像图特征,观察骨质侵蚀发生的部位、形态、边界、内部血流分布等直接征象及滑膜或关节腔积液内点状高回声、痛风石、双轨征等特异性间接征象。结果骨侵蚀在类风湿性关节炎中第五跖趾关节均受累(n=43例,100%),边界模糊(n=40例,93.0%),外形以圆形为主(n=39例,90.7%),滑膜增生(n=38例,88.4%);而在痛风性关节炎中第一跖趾关节均受累(n=52例,100%),边界清晰(n=39例,75%),外形呈椭圆形或圆形(61.5%vs 38.5%),滑膜增生(n=10例,19.2%),两组之间差异均有统计学意义(P<0.001);且在痛风组中出现了特异性间接征象(P<0.001),滑膜或关节腔积液内点状高回声(n=23例,44.2%),痛风石(n=33例,63.5%),双轨征(n=21例,40.4%),而在类风湿性关节炎中均无上述间接征象出现。结论超声可以依据骨侵蚀的特征鉴别类风湿性与痛风性跖趾关节炎。

海底盾构隧道管片接头氯离子侵蚀运移规律研究

随着海底隧道服役时间的延长,氯离子侵蚀对衬砌结构的危害会不断递增,需对此进行深入研究。文章从多孔介质中腐蚀离子运移机理出发,采用渗流与离子运移耦合分析的方法,建立了管片接头氯离子侵蚀运移数值模型,重点分析管片接头位置在海底氯盐环境长期侵蚀作用下的氯离子侵蚀运移规律,得到的主要结论有:孔隙水是氯离子在管片混凝土中侵蚀运移的载体,氯离子在管片中侵蚀运移作用主要包括对流、分子扩散、机械弥散等;随着隧道服役时间的延长,氯离子从管片接头外表面向隧道内部渗透的深度越大;隧道外部水压对管片渗透速度与深度影响显著,外部水压越大海水渗透深度越深;接头局部区域的氯离子侵蚀体现出不均匀分布现象,氯离子浓度较远离接缝处较高,到达临界浓度的时间也较短;近接缝面位置处由于边界条件不同及不连续的影响,存在氯离子运移曲线轨迹。

华北峡谷珍品——河北野三坡“百里峡构造-冲蚀嶂谷”的成因

野三坡国家地质公园位于紫荆关大断裂北端,河北涞水县境内。百里峡构造-冲蚀嶂谷由3条分裂嶂谷组成,总长达52.5km,发育在紫荆关大断裂东侧的中元古界雾迷山组燧石条带白云岩中。中—新生代4期宏大而直立的构造节理,特别是喜马拉雅期南北向追踪张节理,是嶂谷形成的先决条件;更新世阶段地壳迅速的抬升、外力的物理风化作用,特别是晚更新世间歇性山区洪水的冲蚀,是形成嶂谷的直接原因。百里峡构造-冲蚀嶂谷是喀斯特地貌中一种特殊的类型。

钻井液对钻杆接头冲蚀规律的试验研究

钻杆受到钻井液的冲蚀会有不同程度的损伤,若在钻杆接头部位出现冲蚀坑就可能使钻杆失效,引发钻井事故。鉴于此,通过试验分析了钻井液流量、粘度、密度、钻井液中固相颗粒体积分数及固相颗粒粒径对钻杆接头冲蚀量的影响规律。结果表明,钻井液密度对钻杆接头的冲蚀影响基本可以忽略;钻井液流量与粘度的增大会导致冲蚀量增大;固相颗粒是造成钻杆接头冲蚀的主要原因,固相颗粒体积分数的增大与粒径的减小均会导致冲蚀量增加。冲蚀量较大的位置在钻杆内外接头结合处、公接头与钻杆本体焊接后端台阶处以及公接头出口处。因此,应在强度等条件允许的情况下,改进钻杆接头部分的结构与尺寸,使流动平稳地过渡,防止因截面突变而引起涡流的产生或流速的加快,以尽量减少冲蚀量;在钻井过程中,应当采取切实有效的措施加强对固相的控制。

含砂输气管线三通部位的冲蚀仿真模拟

含砂输气管线中三通部位易受到冲蚀破坏。为了准确掌握三通在不同流向及安装位置下冲蚀破坏的具体位置,分析了影响冲蚀速率的主要因素,通过建立CFD仿真模型进行计算分析,指出三通管件两颊部位和迎流壁面处易发生冲蚀,同时部分沉积在管道底部的砂粒也会对管壁造成一定冲蚀。通过单一变量法进行对比分析,结果表明冲蚀速率随着流速、粒子质量流量的增大而增大,但随着形状系数的增大而减小,即粒子越接近于圆球形,冲蚀速率越小,形状系数较小时影响较为明显,较大时影响变小,同时还随粒子直径的增大而增大,但是到一定程度后,不再增大。

类风湿因子与类风湿关节炎疾病活动性评分及关节损害的关系

目的:探讨类风湿因子(RF)与类风湿关节炎(RA)疾病活动性评分(DAS28)及关节X线损害的关系。方法:RA患者53例,速率散射比浊法检测类风湿因子(RF)、补体、免疫球蛋白及C-反应蛋白,魏氏法测定血沉,全自动分析仪检测血常规;拍摄双手和腕关节X线片。比较RA患者RF阳性、阴性者的一般项目、临床检查、实验室检测指标、疾病活动性评分(DAS28)及关节侵蚀程度。结果:RA患者RF阳性、阴性者各指标比较,疾病病程差异有统计学意义(P<0.05);临床检查差异无统计学意义(均P>0.05);实验室检测CRP及IgM水平差异有统计学意义(均P<0.05);RF阳性者DAS28较阴性者明显增高(P<0.05);双手关节侵蚀程度比较差异统计学意义(P>0.05)。结论:RF阳性的RA患者具有更强的疾病活动性,但RF水平与关节侵蚀程度无关。