海水入侵模拟方法VFT3D及应用          下载免费PDF全文

王佳琪  郭芷琳  田勇  范林峰  曾文科  王晓丽  苏皝  Michele Lancia  郑春苗 《水文地质工程地质》2022,49(2):184-194

海水入侵是困扰沿海地区经济社会发展的重大资源、环境问题,严重影响沿海地区地下水资源。定量模拟、预测和可视化管理是对海水入侵进行有效监测和机理分析的重要手段。基于前期海水入侵模拟的理论研究及方法,提出了海水入侵模拟及预测模型VFT3D,该模型综合考虑地表水-地下水对海水入侵的协同控制作用,能够模拟变密度地下水流及复杂反应性迁移,实现模拟海水入侵的完整水文循环过程。文章介绍了VFT3D模型,利用VFT3D模型模拟了一个海水入侵案例,并与SEAWAT模型模拟结果进行了对比分析。结果表明VFT3D 模型模拟水头与SEAWAT模型模拟结果相差不大,但SEAWAT模型无法模拟海水入侵中复杂的化学反应过程。VFT3D 模型模拟发现,水文地球化学过程（阳离子吸附交换作用）对阳离子（Na+、K+、Mg2+和Ca2+）运移产生明显影响,同时引起过渡带中离子组分浓度发生变化,对海水入侵过程产生较大影响。因此,考虑变密度和复杂反应过程,才能更加准确地描述海水入侵,从而有利于地下咸水治理工程的科学实施。  相似文献   

强震作用下液化场地群桩动力响应及p-y曲线     

冯忠居  孟莹莹  张聪  赖德金  朱继新  林路宇 《岩土力学》2022,43(5):1289-1298

为研究液化场地中群桩在强震作用下的动力响应特征及桩侧土抗力-桩土相对位移（p-y）曲线规律,依托海文大桥实体工程,基于振动台模型试验,开展了0.15g～0.35g地震动作用饱和粉细砂土层不同埋置深度下的砂土孔压比、桩身弯矩及p-y曲线动力响应研究。结果表明：地震动强度达到0.25g时,不同埋置深度下的饱和粉细砂土层孔压比均大于0.8,产生液化现象,且随埋置深度增加,孔压比增长时刻明显滞后;不同埋置深度下,桩身弯矩最大值均位于液化土层和非液化土层分界面处;同一埋置深度时,随地震动强度的增大,p-y曲线所包围的面积逐渐增大,其整体斜率逐渐变小,说明桩-土相互作用动力耗能逐渐增大,桩周土体刚度逐渐减小;随埋置深度增加,p-y曲线所包围的面积逐渐减小,其整体斜率逐渐增大,说明桩-土相互作用动力耗能逐渐减小,桩周土体刚度逐渐增大。因此,液化场地桥梁群桩抗震设计时,应综合考虑液化土层与桩基础的相互位置关系,确保桩基础在液化土层与非液化土层分界处的抗弯承载能力。  相似文献   

桩前溶洞对抗滑桩嵌固端稳定性影响物理模型试验研究     

刘孟瀚  范秋雁  李天雨  李武奇  梁家珲  韩进仕 《中国岩溶》2022,41(1):59-66

Simulation and assessment of soil temperature and moisture in seasonally frozen soil regions of the Tibetan Plateau based on SHAW model北大核心CSCD     

薛伟  周毓彦  刘建伟  鲁帆  侯保灯  胡莹莹  肖伟华 《冰川冻土》2023,(1):54-66

In recent years,more and more attention has been paid to the problem of the cryosphere changes on the Tibetan Plateau,and it has gradually become a hot issue for scholars. Known as the“water tower of Asia”,the Tibetan Plateau is the source of many major rivers in Asia. Under the combined influence of climate change and human activities,water resources on the Tibetan Plateau have undergone profound changes,especially soil water,as an important component of water resources,which plays an important role in regulating vegetation and crop growth,rainfall and runoff. However,global warming leads to the degradation of permafrost and seasonal⁃ ly frozen soil,which affects the original water cycle process and the spatial and temporal pattern of water re⁃ sources by changing the properties of soil water storage and water transport. In the Tibetan Plateau,where there are few data,it is difficult to directly study the soil water cycle process under freezing-thawing by using original data. Therefore,it is an important means to simulate the variation characteristics of soil water and temperature under freezing-thawing in seasonally frozen soil regions of the Tibetan Plateau by using coupling model of soil water and heat. Aiming at the key problem of the difference of soil temperature and moisture characteristics in typical seasonally frozen soil regions under different meteorological conditions,this paper simulated the charac⁃ teristics of soil moisture and temperature change in Maqu,Naqu（Nagqu）and Shiquanhe from 2017 to 2018 by using SHAW（Simultaneous Heat and Water）model and three soil moisture characteristic curve models. The simulation effect and variation characteristics of soil moisture and temperature under different meteorological conditions were analyzed,and the influence of soil moisture characteristic curve model on the simulation effect was studied. The results show that SHAW model can well simulate the temporal variation and vertical distribu⁃ tion of soil temperature and moisture under different meteorological conditions. The simulation effect of soil tem⁃ perature is better than that of soil moisture. The average NSE,R2 and RMSE of soil temperature are 0. 88,0. 96 and 2. 20 ℃,respectively. The mean NSE,R2 and RMSE of soil moisture are 0. 60,0. 72 and 0. 03 m3·m-3,respec⁃ tively. In terms of different meteorological conditions,the simulation effect of soil temperature in relatively dry region was significantly better than that in humid region,while the simulation effect of soil water in relatively hu⁃ mid region was significantly better than that in arid region. From different depths in soil,the simulation effect of soil temperature decreases gradually with the increase of depth,while the simulation effect of soil moisture in the middle and lower layers is better than that in the surface layer. From the view of different soil moisture character⁃ istic curve models,different soil water characteristic curve models have no significant effect on soil temperature simulation effect,but there are significant differences in soil moisture simulation effect. In addition,there are great differences and uncertainties in simulating soil temperature and moisture in different freezing-thawing stag⁃ es. With the increasing trend of climate warming,permafrost and seasonally frozen soil on the Tibetan Plateau may continue to degrade,may change the current water resources pattern,resulting in frequent extreme weather events. Therefore,from the perspective of numerical simulation,this paper verified the applicability of soil moisture and heat coupling model in soil temperature and moisture simulation under different meteorological con⁃ ditions,revealed the influence of precipitation and temperature on soil temperature and moisture simulation at different depths in seasonally frozen soil regions,and analyzed the differences in simulation effects of different soil moisture characteristic curve models. The results provide reference for the study of soil water resources vari⁃ ation under freezing-thawing conditions. © 2023 Chinese Journal of General Practitioners. All rights reserved.  相似文献   

安徽沙坪沟斑岩钼矿床赋矿岩体钾质交代作用及其微量元素和Sr-Nd同位素响应     

何俊  徐晓春  王萍  范子良  傅仲阳  王波华  张怀东  谢巧勤 《矿床地质》2018,37(3):611-629

以沙坪沟钼矿主要的赋矿岩石——石英正长岩和花岗斑岩为对象,通过对比不同蚀变强度岩石的岩相学、岩石地球化学和同位素特征,研究该矿床的钾质交代作用-矿化特征,探讨不同热液蚀变的元素组合、蚀变过程中的元素迁移和Sr-Nd同位素的变化及其成因、不同蚀变的物理化学条件差异及其与矿化的关系,进而揭示蚀变-成矿热液流体的特征和起源。研究表明,石英正长岩和花岗斑岩的地球化学特征总体相似,显示其属同源岩浆演化产物,二者均受到钾质蚀变,但蚀变强度相差较大。钾质蚀变岩石的化学成分表现为高K_2O、Rb和低Na_2O、CaO、Sr、Ba,不同蚀变强度的岩石Rb/Sr和Sr同位素组成差别较大,花岗斑岩样品数据更显离散,甚至出现异常低的锶同位素初始值,表明热液蚀变强烈改造了Rb-Sr同位素体系,而Sm-Nd体系基本保持稳定。这一现象在东秦岭-大别钼矿带中典型的斑岩钼矿床也有出现,显示该成矿带具有相似的蚀变类型、热液起源和演化特征。而且钾长石化后期至黄铁云(绢)英岩化阶段也是最主要的钼成矿期,表明这期间流体系统pH值的降低致使Mo元素从流体中沉淀成矿。对比斑岩铜、铜-钼矿床和钼矿床的蚀变特征及其过程中元素和同位素的变化可以发现,这3种矿床均发育碱质交代作用,但蚀变强度、热液的Rb-Sr分异程度及其对原岩的改造程度存在较大差异,这暗示了各自特有的成岩、成矿物质和流体来源及大地构造背景。  相似文献   

重复剪切作用下结构面起伏角度对其力学特性影响研究          下载免费PDF全文

魏继红  王武超  杨圆圆  朱峰  范昊天 《水文地质工程地质》2018,(1):60-68

在室内直剪试验的基础上,研究了重复剪切作用下起伏角对结构面变形和强度的影响。采用钢制模具和混凝土材料预制4种起伏角度结构面,分别在5级法向应力下进行6次直剪试验,记录每次剪切过程中的切向应力和法向位移随切向位移的变化。通过对切向应力和法向位移随切向位移变化曲线分析可知,首次剪切时,法向应力和起伏角度越大,结构面剪切破坏方式越容易从滑移破坏过渡为剪断破坏,对于同一种剪切破坏方式,法向应力越大,对结构面磨损或剪断的作用越强烈,峰值剪胀位移越小,起伏角度越大,锯齿被磨损或剪断的高度越大;第2次剪切开始,不论法向应力和起伏角度如何,结构面的剪切破坏方式基本上都转变为滑移破坏。  相似文献   

中国—吉尔吉斯天山成矿单元划分及其特征   总被引：1，自引：0，他引：1  

孟广路  王斌  范堡程  曹积飞  李宝强 《地质通报》2015,34(4):696-709

中国—吉尔吉斯天山地处中亚天山造山带中段,是古亚洲构造域的重要组成部分,地质构造复杂,矿产资源丰富。在收集境内、外大量地质、矿产资料及图件的基础上,通过近年来对研究区内地层、构造、岩浆及矿产的研究,在大地构造单元划分基础上对研究区内天山进行了成矿单元划分,划分出北天山—伊犁、中天山和南天山—塔里木3个成矿省,进一步划分为22个成矿带和58个成矿亚带,总结了各成矿单元的地质及矿产特征,为天山成矿带矿产勘查和地质大调查工作部署提供有益的思路和依据。  相似文献   

重探试验锤击数的杆径换算研究          下载免费PDF全文

范建好 《探矿工程》2015,42(1):72-75

目前,国内绝大多数规范规定重探试验应采用φ42 mm钻杆,但从施工方便等因素的考虑,很多工程勘察单位趋向于采用φ50 mm的钻杆进行重探试验。通过分析重探试验要点及其影响因素,基于重探试验锤击数修正系数表,推导出杆径换算系数为0.89,并以海南省某岛礁水运工程实例加以验证。结果表明,同一地貌单元,埋深12 m以浅的珊瑚碎屑层,采用φ42 mm钻杆进行重探试验的击数与采用φ50 mm钻杆进行重探试验的击数之比值为0.875,与推导结果基本一致。  相似文献   

岑溪:努力推进国土资源节约集约利用     

玉莹莹 《南方国土资源》2015,(4):55

<正>2015年3月以来,广西岑溪市国土资源局采取强有力措施,努力提升国土资源节约集约利用水平。一是加大征地拆迁和盘活存量土地力度。目前,岑溪市共取得上级批准而储备的土地198公顷,各相关镇政府和征地工作队将进一步加大征地力度,尽快完成征地,确保及时依法供地,进一步提高土地利用率。  相似文献   

山东精细化海区风的MOS预报方法研究   总被引：1，自引：0，他引：1  

荣艳敏  阎丽凤  盛春岩  范苏丹  车军辉 《海洋预报》2015,32(3):59-67

基于中尺度数值模式WRF_RUC的预报产品,采用逐步回归的MOS方法,对山东12个精细海区代表站有关大风进行解释应用。对2013年9月—2014年4月海区风的客观预报产品进行检验,结果表明:MOS预报方法对6级以上日最大风速有较好的预报能力,较WRF_RUC模式直接输出的预报结果有了明显的提高,但对4级以下小风预报效果较差。选取4级风作为阈值,当WRF_RUC模式预报风力大于4级时,用MOS预报结果替换,显著提高了风速分级预报效果,无论是4级以下小风还是6级以上大风,MOS预报评分都要高于WRF_RUC模式预报。将平均风速与阵风的统计关系应用到阵风客观预报中,MOS方法对于改进的日极大风速的预报效果有明显提高,对10级强风也有一定的预报能力。  相似文献