本文主要研究内容
作者乔宇（2019）在《长江口表层沉积物侵蚀特性研究》一文中研究指出：全球范围内,有半数以上的河口海岸区域面临着侵蚀灾害加剧的风险。在自然条件变化和人类活动导致的入海泥沙通量持续减少的背景之下,长江三角洲淤涨速率下降,甚至面临大范围侵蚀的威胁,该侵蚀趋势不仅会导致宝贵的滩涂湿地丧失,还会直接增加海岸工程的风险。河口区泥沙运动临界条件的研究是泥沙动力学的基础理论课题,能够为地貌冲淤演化与预测提供重要依据,因此已成为河口海岸泥沙运动与河床演变研究的应用热点问题。本文聚焦长江口,基于2015~2017年间长江口多次大范围底质采样观测分析,对长江口表层沉积物的基本物理性状包括粒度组成、含水量、容重等特征与分布进行了研究,同时利用室内微观侵蚀系统(U-GEMS)和流变系统,分别试验探究了河口原状表层沉积物的剪切起动与流变特性。结合理论分析,初步阐明了表层沉积物侵蚀特性与泥沙物理性状的响应关系及作用机理,给出了长江口及其部分邻近海域的表层沉积物临界起动应力空间分布格局,尝试构建了适用于长江口黏性细颗粒表层沉积物的起动应力公式,可为长江口潮流-泥沙数值模拟的改进提供重要参数,为长江口动力机制、冲淤趋势和地貌演变的研究提供科学依据。得到的核心认识如下:1.首次对长江口及其邻近海域大范围表层沉积物的临界起动应力进行观测和量化,并给出分布格局。其变化范围主要为0.3~0.9 Pa,河口最大浑浊带和口外泥质区附近较小,浑浊带上游河槽和口外海滨北部较大。口内河槽区域,北支表层沉积物抗侵蚀能力弱,起动应力为0.45~0.6 Pa;南支、南港和北港上段临界起动应力高于0.75 Pa,难以继续冲刷;最大浑浊带所处河段,临界起动应力分布不均,平均小于0.6 Pa;北港口门及崇明东滩、横沙浅滩前缘附近表层沉积物粒径粗,含水量低,起动应力约0.8 Pa;南槽表层沉积物的粒度和含水量差异大,起动应力在0.5~0.7 Pa之间变化。口外海滨区域,北部以粗颗粒残留砂为主的表层沉积物临界起动应力超过0.8 Pa,难以被侵蚀搬运;南部海域整体分布范围约0.35~0.6 Pa,泥质区一带表层沉积物临界起动应力仅0.4 Pa左右,极易起动,其再悬浮泥沙是维持河口最大浑浊带含沙量的重要物质来源。杭州湾北岸海域表层沉积物的临界起动应力由东向西从0.6 Pa增至0.8 Pa,抗侵蚀能力逐渐增强,冲刷趋势将得到缓冲。2.给出长江口大范围原状表层沉积物的含水量分布格局,其变化范围在30%~150%之间,口内河槽区域北高南低,口门及口外海滨区域北低南高。含水量的平均水平和可变化范围与黏土含量呈正相关关系。在最大浑浊带上游区域,含水量的横向分布表现为北高南低,南北相差70%;最大浑浊带由于滩槽交错分布和径潮流相互作用的复杂动力条件,含水量在30%~150%之间不等;口外海滨区域含水量分布呈北低南高,北部普遍低于60%,而靠近泥质区高达130%。湿容重范围为1000~1800 kg/m3,与含水量的空间分布相关性良好。含水量、湿容重等能够反映沉积物固结程度的物理性状受到粒度组成的影响。统计不同区域含水量与各粒度组分含量发现,当沉积物中黏土、粉砂含量越多,砂含量越少时,孔隙率越大,含水量的平均水平和可变化范围也相应增大。此时含水量的大范围变动主要是由不同固结程度下床沙与底层水体的交换混合强度不一或孔隙水饱和度不同造成。3.沉积物的表面侵蚀有“突变型”、“渐变型”等不同泥沙起动形态,侵蚀过程受粒度与含水量的共同控制;体积侵蚀则主要受细颗粒泥沙之间的粘结力作用控制。沉积物表面侵蚀有“突变起动型”、“渐变起动型”等不同的泥沙起动形态。通常沉积物的含水量由高变低时,临界起动应力增大。而当含水量低于90%,湿容重大于1250 kg/m3,固结程度开始增强时,沉积物的粒度组成变化对临界起动应力的影响程度开始提升。当沉积物中细颗粒组分含量高时(黏土含量大于20%,砂含量小于20%,中值粒径小于20μm),黏土含量变化对含水量范围以及泥沙黏性特征的影响显著,临界起动应力变化范围较大;反之粗颗粒组分占比高时,颗粒间粘结作用弱化,重力抗侵蚀作用突出,临界起动应力随粒径增大而增大。在强动力条件下,当沉积物细颗粒组分占比高,泥沙黏性特征十分显著时,不排水剪切强度大,体积侵蚀较难发生,反之亦然。长江口表层沉积物的黏土含量低于20%,砂含量高于20%,中值粒径大于20μm时,在强动力条件下较易被整体起动冲刷,出现体积侵蚀。含水量可以改变细颗粒泥沙黏性特征的表现,因此对体积侵蚀的临界条件也有一定影响,尤其当含水量高于50%,湿容重小于1500 kg/m3时,不排水剪切强度随含水量的升高而有所下降,并且影响程度随黏土含量的增多而愈加强烈。
Abstract
quan qiu fan wei nei ,you ban shu yi shang de he kou hai an ou yu mian lin zhao qin shi zai hai jia ju de feng xian 。zai zi ran tiao jian bian hua he ren lei huo dong dao zhi de ru hai ni sha tong liang chi xu jian shao de bei jing zhi xia ,chang jiang san jiao zhou yu zhang su lv xia jiang ,shen zhi mian lin da fan wei qin shi de wei xie ,gai qin shi qu shi bu jin hui dao zhi bao gui de tan tu shi de sang shi ,hai hui zhi jie zeng jia hai an gong cheng de feng xian 。he kou ou ni sha yun dong lin jie tiao jian de yan jiu shi ni sha dong li xue de ji chu li lun ke ti ,neng gou wei de mao chong yu yan hua yu yu ce di gong chong yao yi ju ,yin ci yi cheng wei he kou hai an ni sha yun dong yu he chuang yan bian yan jiu de ying yong re dian wen ti 。ben wen ju jiao chang jiang kou ,ji yu 2015~2017nian jian chang jiang kou duo ci da fan wei de zhi cai yang guan ce fen xi ,dui chang jiang kou biao ceng chen ji wu de ji ben wu li xing zhuang bao gua li du zu cheng 、han shui liang 、rong chong deng te zheng yu fen bu jin hang le yan jiu ,tong shi li yong shi nei wei guan qin shi ji tong (U-GEMS)he liu bian ji tong ,fen bie shi yan tan jiu le he kou yuan zhuang biao ceng chen ji wu de jian qie qi dong yu liu bian te xing 。jie ge li lun fen xi ,chu bu chan ming le biao ceng chen ji wu qin shi te xing yu ni sha wu li xing zhuang de xiang ying guan ji ji zuo yong ji li ,gei chu le chang jiang kou ji ji bu fen lin jin hai yu de biao ceng chen ji wu lin jie qi dong ying li kong jian fen bu ge ju ,chang shi gou jian le kuo yong yu chang jiang kou nian xing xi ke li biao ceng chen ji wu de qi dong ying li gong shi ,ke wei chang jiang kou chao liu -ni sha shu zhi mo ni de gai jin di gong chong yao can shu ,wei chang jiang kou dong li ji zhi 、chong yu qu shi he de mao yan bian de yan jiu di gong ke xue yi ju 。de dao de he xin ren shi ru xia :1.shou ci dui chang jiang kou ji ji lin jin hai yu da fan wei biao ceng chen ji wu de lin jie qi dong ying li jin hang guan ce he liang hua ,bing gei chu fen bu ge ju 。ji bian hua fan wei zhu yao wei 0.3~0.9 Pa,he kou zui da hun zhuo dai he kou wai ni zhi ou fu jin jiao xiao ,hun zhuo dai shang you he cao he kou wai hai bin bei bu jiao da 。kou nei he cao ou yu ,bei zhi biao ceng chen ji wu kang qin shi neng li ruo ,qi dong ying li wei 0.45~0.6 Pa;na zhi 、na gang he bei gang shang duan lin jie qi dong ying li gao yu 0.75 Pa,nan yi ji xu chong shua ;zui da hun zhuo dai suo chu he duan ,lin jie qi dong ying li fen bu bu jun ,ping jun xiao yu 0.6 Pa;bei gang kou men ji chong ming dong tan 、heng sha jian tan qian yuan fu jin biao ceng chen ji wu li jing cu ,han shui liang di ,qi dong ying li yao 0.8 Pa;na cao biao ceng chen ji wu de li du he han shui liang cha yi da ,qi dong ying li zai 0.5~0.7 Pazhi jian bian hua 。kou wai hai bin ou yu ,bei bu yi cu ke li can liu sha wei zhu de biao ceng chen ji wu lin jie qi dong ying li chao guo 0.8 Pa,nan yi bei qin shi ban yun ;na bu hai yu zheng ti fen bu fan wei yao 0.35~0.6 Pa,ni zhi ou yi dai biao ceng chen ji wu lin jie qi dong ying li jin 0.4 Pazuo you ,ji yi qi dong ,ji zai xuan fu ni sha shi wei chi he kou zui da hun zhuo dai han sha liang de chong yao wu zhi lai yuan 。hang zhou wan bei an hai yu biao ceng chen ji wu de lin jie qi dong ying li you dong xiang xi cong 0.6 Pazeng zhi 0.8 Pa,kang qin shi neng li zhu jian zeng jiang ,chong shua qu shi jiang de dao huan chong 。2.gei chu chang jiang kou da fan wei yuan zhuang biao ceng chen ji wu de han shui liang fen bu ge ju ,ji bian hua fan wei zai 30%~150%zhi jian ,kou nei he cao ou yu bei gao na di ,kou men ji kou wai hai bin ou yu bei di na gao 。han shui liang de ping jun shui ping he ke bian hua fan wei yu nian tu han liang cheng zheng xiang guan guan ji 。zai zui da hun zhuo dai shang you ou yu ,han shui liang de heng xiang fen bu biao xian wei bei gao na di ,na bei xiang cha 70%;zui da hun zhuo dai you yu tan cao jiao cuo fen bu he jing chao liu xiang hu zuo yong de fu za dong li tiao jian ,han shui liang zai 30%~150%zhi jian bu deng ;kou wai hai bin ou yu han shui liang fen bu cheng bei di na gao ,bei bu pu bian di yu 60%,er kao jin ni zhi ou gao da 130%。shi rong chong fan wei wei 1000~1800 kg/m3,yu han shui liang de kong jian fen bu xiang guan xing liang hao 。han shui liang 、shi rong chong deng neng gou fan ying chen ji wu gu jie cheng du de wu li xing zhuang shou dao li du zu cheng de ying xiang 。tong ji bu tong ou yu han shui liang yu ge li du zu fen han liang fa xian ,dang chen ji wu zhong nian tu 、fen sha han liang yue duo ,sha han liang yue shao shi ,kong xi lv yue da ,han shui liang de ping jun shui ping he ke bian hua fan wei ye xiang ying zeng da 。ci shi han shui liang de da fan wei bian dong zhu yao shi you bu tong gu jie cheng du xia chuang sha yu de ceng shui ti de jiao huan hun ge jiang du bu yi huo kong xi shui bao he du bu tong zao cheng 。3.chen ji wu de biao mian qin shi you “tu bian xing ”、“jian bian xing ”deng bu tong ni sha qi dong xing tai ,qin shi guo cheng shou li du yu han shui liang de gong tong kong zhi ;ti ji qin shi ze zhu yao shou xi ke li ni sha zhi jian de nian jie li zuo yong kong zhi 。chen ji wu biao mian qin shi you “tu bian qi dong xing ”、“jian bian qi dong xing ”deng bu tong de ni sha qi dong xing tai 。tong chang chen ji wu de han shui liang you gao bian di shi ,lin jie qi dong ying li zeng da 。er dang han shui liang di yu 90%,shi rong chong da yu 1250 kg/m3,gu jie cheng du kai shi zeng jiang shi ,chen ji wu de li du zu cheng bian hua dui lin jie qi dong ying li de ying xiang cheng du kai shi di sheng 。dang chen ji wu zhong xi ke li zu fen han liang gao shi (nian tu han liang da yu 20%,sha han liang xiao yu 20%,zhong zhi li jing xiao yu 20μm),nian tu han liang bian hua dui han shui liang fan wei yi ji ni sha nian xing te zheng de ying xiang xian zhe ,lin jie qi dong ying li bian hua fan wei jiao da ;fan zhi cu ke li zu fen zhan bi gao shi ,ke li jian nian jie zuo yong ruo hua ,chong li kang qin shi zuo yong tu chu ,lin jie qi dong ying li sui li jing zeng da er zeng da 。zai jiang dong li tiao jian xia ,dang chen ji wu xi ke li zu fen zhan bi gao ,ni sha nian xing te zheng shi fen xian zhe shi ,bu pai shui jian qie jiang du da ,ti ji qin shi jiao nan fa sheng ,fan zhi yi ran 。chang jiang kou biao ceng chen ji wu de nian tu han liang di yu 20%,sha han liang gao yu 20%,zhong zhi li jing da yu 20μmshi ,zai jiang dong li tiao jian xia jiao yi bei zheng ti qi dong chong shua ,chu xian ti ji qin shi 。han shui liang ke yi gai bian xi ke li ni sha nian xing te zheng de biao xian ,yin ci dui ti ji qin shi de lin jie tiao jian ye you yi ding ying xiang ,you ji dang han shui liang gao yu 50%,shi rong chong xiao yu 1500 kg/m3shi ,bu pai shui jian qie jiang du sui han shui liang de sheng gao er you suo xia jiang ,bing ju ying xiang cheng du sui nian tu han liang de zeng duo er yu jia jiang lie 。
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论文作者分别是来自华东师范大学的乔宇，发表于刊物华东师范大学2019-07-02论文，是一篇关于表层沉积物论文,侵蚀特性论文,临界起动应力论文,含水量论文,粒度论文,长江口论文,华东师范大学2019-07-02论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自华东师范大学2019-07-02论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。
标签：表层沉积物论文; 侵蚀特性论文; 临界起动应力论文; 含水量论文; 粒度论文; 长江口论文; 华东师范大学2019-07-02论文;