土遗址全长黏结式锚固系统动力响应解析方法     

芦苇  赵冬  李东波  毛筱霏 《岩土力学》2020,41(4):1377-1387

以纵向宽大裂隙引起的夯土城墙遗址稳定问题为背景，建立危险土体?锚杆?稳定土体锚固系统简化力学模型。该模型将土体对锚杆的摩阻作用简化为一个线性弹簧和一个与速度相关的阻尼器的并联机构，将裂隙段锚杆对两侧土体的拉结作用简化为一个线性弹簧。基于弹性体动力理论建立锚固系统动力平衡方程，并推导了锚杆轴力和位移的动力响应解析解。最后，以新疆高昌故城南城墙某段锚固工程为例对提出的解析方法进行了说明，明确了锚杆轴力响应特征及其分布规律，并通过数值分析对其合理性进行了验证。结果表明：在动力作用下同一位置锚杆的轴力响应呈围绕静力平衡位置的波动形态，轴力峰值点位于裂隙附近，且逐渐向临空端和锚固端指数衰减。在考虑地震加速度沿遗址高度的放大效应后能够获得较精确的锚杆轴力响应。  相似文献   

扎鲁特地区无烟煤分子结构特征和模型构建     

张帅  马汝嘉  刘路  张浩  刘钦甫 《煤田地质与勘探》2020,48(1):62-69

为了构建内蒙古扎鲁特地区无烟煤的分子结构模型，采用工业分析、元素分析、核磁共振碳谱、高分辨率透射电镜和X射线光电子能谱等测试方法对该地区无烟煤的分子结构进行研究。结果表明无烟煤分子结构中以芳香碳为主，脂肪碳以短烷基侧链和环烷烃为主。煤分子结构中氧原子主要以酚羟基和醚氧基的形式存在，氮原子主要以吡咯型氮和吡啶型氮的形式存在，硫原子主要的赋存形态是硫醇硫酚。结合由核磁共振碳谱测得的煤结构参数和由高分辨率透射电镜测得的芳香环尺寸和含量，构建了无烟煤大分子平均结构模型。对构建的模型进行了结构优化与能量分析，发现煤分子结构的芳香片层趋于平行排列，非键结势能中的范德华力是保持煤结构稳定的主要因素。本研究为采用分子动力学模拟从分子尺度研究扎鲁特地区无烟煤在石墨化过程中，其芳香碳层的拼叠过程及其反应路径提供了模型基础。   相似文献   

基于VG模型确定土水特征曲线基本参数     

潘登丽  倪万魁  苑康泽  张镇飞  王熙俊 《工程地质学报》2020,28(1):69-76

土水特征曲线基本参数(进气值、残余吸力值和反弯点的斜率等)在非饱和土的强度理论、渗流理论以及体变特性等方面都是非常重要的参数,常常通过传统画图法来确定,其精确度难以保证。以洛川标准剖面4层原状黄土为研究对象,基于VG模型提出单峰和双峰SWCC基本参数的确定方法;采用滤纸法测得SWCC数据点,基于VG模型进行最优化拟合,获取拟合参数,利用单峰和双峰SWCC数据点验证该方法的可行性;进行自然状态下的水分蒸发试验,根据质量含水率与蒸发时间的关系确定蒸发残余饱和度Srzf,依据Sr1、Sr2(Sr1和Sr2分别由确定残余状态的两种方法得到)与Srzf的相对误差值,比较了两种确定残余状态的方法。结果表明:对于单峰和双峰SWCC曲线,该方法都可以得到合理的基本参数并有效地确定其残余状态。  相似文献   

南盘江—右江盆地构造演化与金锑成矿作用     

杨成富  刘建中  顾雪祥  王泽鹏  陈发恩  王大福  徐良易  李俊海 《地球学报》2020,41(2):280-292

南盘江—右江盆地具独特的盆地构造演化历史和背景,是西南低温成矿域的重要组成部分,广泛发育有Au-As-Sb-Hg-Tl等低温热液矿床,金锑成矿作用与盆地构造演化密切相关。本文系统总结南盘江—右江盆地构造演化过程和历史,分析盆地演化对沉积地层、沉积相带分布、古地理变迁等的控制作用。盆地内金锑矿床受构造和有利岩性组合控矿明显,结合南盘江—右江盆地内Cu-W-Sn-Pb-Zn-Au-Sb-Hg等矿床空间分布特征及规律,探讨盆地构造演化与金锑成矿作用和成矿效应的关系。类比斑岩-矽卡岩-浅成低温热液型多金属矿床最新研究成果,建立南盘江—右江盆地以陆内斑岩型铜矿床为中心,上部或边部矽卡岩型铜矿床、脉状钨-锡-银-铅-锌矿床和远端低温热液金-银-锑-汞矿床的找矿预测模型,模型对南盘江—右江成矿区深部斑岩型矿床或与斑岩体有关的矽卡岩型矿床的找矿勘查具有重要意义。  相似文献   

塔河油田奥陶系储层构造应力场研究     

刘佳庚  李静  苏玉亮  范作松  刘旭亮  郭豪 《地质力学学报》2020,26(1):48-54

油气储层构造应力场的分布特征，对油气运移、注采井网布置、储层改造等具有重要意义。为此，文章从塔河油田AD13井区的地质构造演化入手，基于油田测井资料，结合弹性力学及有限元理论，建立研究区地应力弹性力学计算模型，利用有限元软件对研究区储层地应力进行模拟研究，并将模拟结果与现场地应力实测值进行对比分析。结果表明，研究区最大水平主应力为102~130 MPa，最小水平主应力为87~110 MPa，均为压应力；研究区东部及南部最大水平主应力方向为北东向，西北部最大水平主应力方向为北东东向，西南部最大水平主应力方向为南东向，地应力大小及方向均与实际结果相符。研究结果可为研究区油气勘探开发工程提供科学依据。   相似文献   

基于GridMet模型的浙江省温湿指数空间分布及地形影响分析     

施国萍  何永健  张眉  邱新法  曾燕 《地球信息科学学报》2019,21(12):1923-1933

温湿指数是气候舒适度评价模型之一,通过温度与湿度的组合反映人体与周围环境的热量交换,本文利用2003-2018年浙江省及其周边71个气象站点月平均气温、地面水汽压数据,以及MODIS水汽产品,基于GridMet模型模拟了浙江省各月温湿指数空间分布（100 m×100 m）,分析了浙江省温湿指数随地形因子（海拔、坡度、坡向）变化的特征;讨论了各地形因子对温湿指数空间分布的影响程度。结果表明：① 海拔、坡度、坡向3个地形因子中,1月温湿指数随坡向的变化最大,7月最小;② 同坡向上,坡度变化对1月温湿指数影响较大,而海拔变化则是对7月影响最大;③ 南坡1月温湿指数随海拔和坡度增加均略为增加,南坡其他月份及北坡各月均为随海拔和坡度增加温湿指数减小;④ 北坡相对于南坡而言,海拔和坡度对温湿指数的影响更为明显。浙江大部分山区由于地形影响,夏季较为“舒适”,适宜建立避暑消夏的旅游项目。  相似文献   

对流层延迟与可降水量直接转换模型研究     

李黎  宋越  易金花  田莹  周嘉陵 《大地测量与地球动力学》2019,39(5):492-495

采用线性回归和最小二乘法拟合建立无线电探空可降水量（RS-PWV）与GPS对流层延迟（GPS-ZTD）、地面温度及大气压之间的直接转换模型，并将直接转换模型得到的PWV分别与RS-PWV及GPS反演得到的可降水量（GPS-PWV）进行比较。结果表明，RS-PWV与GPS-ZTD之间存在良好的线性关系，相关系数达0.927 6；RS-PWV与4阶拟合温度和大气压呈现较好的相关性，相关系数分别为0.640 1和－0.626 3；基于ZTD的单阶单因子模型PWV与GPS-PWV的相关系数达到0.969 9；基于ZTD、温度及大气压的单阶多因子模型PWV比基于ZTD的单阶单因子模型PWV精度明显提高，RMS从4.3 mm提高到3.3 mm。  相似文献   

Liquefaction potential evaluations by energy-based method and stress-based method for various ground motions     

《Soil Dynamics and Earthquake Engineering》2015

An energy-based liquefaction potential evaluation method (EBM) previously developed was applied to a uniform sand model shaken by seismic motions recorded at different sites during different magnitude earthquakes. It was also applied to actual liquefaction case histories in Urayasu city during the 2011 M9.0 Tohoku earthquake and in Tanno-cho during the 2003 M8.0 Tokachi-oki earthquake. In all these evaluations, the results were compared with those by the currently used stress-based method (SBM) under exactly the same seismic and geotechnical conditions. It was found that EBM yields similar results with SBM for several ground motions of recent earthquakes but has easier applicability without considering associated parameters. In Urayasu city, the two methods yielded nearly consistent results by using an appropriate coefficient in SBM for the M9.0 earthquake, though both overestimated the actual liquefaction performance, probably because effects of plasticity and aging on in situ liquefaction strength were not taken into account. In Tanno-cho, EBM could evaluate actual liquefaction performance due to a small-acceleration motion during a far-field large magnitude earthquake while SBM could not.  相似文献   

Severe soil erosion during a 3‐day exceptional rainfall event: combining modelling and field data for a fallow cereal field          下载免费PDF全文

Manuel López‐Vicente  Laura Quijano  Leticia Gaspar  Leticia Palazón  Ana Navas 《水文研究》2015,29(10):2358-2372

Exceptional rainfall events cause significant losses of soil, although few studies have addressed the validation of model predictions at field scale during severe erosive episodes. In this study, we evaluate the predictive ability of the enhanced Soil Erosion and Redistribution Tool (SERT‐2014) model for mapping and quantifying soil erosion during the exceptional rainfall event (~235 mm) that affected the Central Spanish Pyrenees in October 2012. The capacity of the simulation model is evaluated in a fallow cereal field (1.9 ha) at a high spatial scale (1 × 1 m). Validation was performed with field‐quantified rates of soil loss in the rills and ephemeral gullies and also with a detailed map of soil redistribution. The SERT‐2014 model was run for the six rainfall sub‐events that made up the exceptional event, simulating the different hydrological responses of soils with maximum runoff depths ranging between 40 and 1017 mm. Predicted average and maximum soil erosion was 11 and 117 Mg ha^?1 event^?1, respectively. Total soil loss and sediment yield to the La Reina gully amounted to 16.3 and 9.0 Mg event^?1. These rates are in agreement with field estimations of soil loss of 20.0 Mg event^?1. Most soil loss (86%) occurred during the first sub‐event. Although soil accumulation was overestimated in the first sub‐event because of the large amount of detached soil, the enhanced SERT‐2014 model successfully predicted the different spatial patterns and values of soil redistribution for each sub‐event. Further research should focus on stream transport capacity. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Modified Rindler acceleration as a nonlinear electromagnetic effect     

《Astroparticle Physics》2015

The model proposed originally by Mannheim and Kazanas for fitting the shapes of galactic rotation curves has recently been considered by Grumiller to describe gravity of a central object at large distances. Herein we employ the same geometry within the context of nonlinear electrodynamics (NED). Pure electrical NED model is shown to generate the novel Rindler acceleration term in the metric which explains anomalous behaviors of test particles/satellites. Remarkably a pure magnetic model of NED yields flat rotation curves that may account for the missing dark matter. Weak and strong energy conditions are satisfied in such models of NED.  相似文献