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陆明勇 《大地测量与地球动力学》2007,27(4):105-111

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Effects of frictional forces acting on sidewalls of buried box culverts     

Junsuk Kang  Frazier Parker  Young J. Kang  Chai H. Yoo 《国际地质力学数值与分析法杂志》2008,32(3):289-306

The effects of frictional forces acting on the sidewalls of buried box culverts are presented as determined with finite element method (FEM) and detailed soil modelling. The possibility of reducing earth pressure on deeply buried concrete box culverts by the imperfect trench installation (ITI) method has been contemplated during the last several decades. There have been limited research results published primarily regarding the qualitative aspect of load reduction in ITIs. It was found during the course of this study that significant frictional forces develop along the sidewalls of box culverts and adjacent sidefills in ITIs. Current American Association of State Highway and Transportation Officials provisions do not consider these frictional forces, but they cannot be neglected in ITIs, as their effect is dominant. An optimum geometry for the soft zone in ITIs is presented to maximize earth load reductions. The soil–structure interaction at the box culvert–soil interface was found to have a significant effect on total earth pressure acting on the bottom slab. Predictor equations for earth load reduction rates were formulated for ITIs incorporating the optimum soft zone geometry based on the FEM. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

弧形防波堤波浪力试验研究     

赵利平  朱亚州  谢奥运  邹俊飞 《海洋工程》2015,33(5):35-42

在圆筒形防波堤和V形防波堤的基础上,结合离岸堤后形成V形和半圆形连续出现的韵律海岸的地貌平面形态特点,提出一种前墙为连续的半圆筒形防波堤形式。通过在波浪水槽内进行规则波物理模型试验,探究这一新型防波堤的波压力分布规律及波高、周期、水深等因素对波压力的影响。将试验结果与海港水文公式和合田良实公式计算的理论值对比分析,给出了以合田良实公式的折减系数来拟合新型弧形防波堤波浪总水平力的计算公式。结果表明:新型弧形防波堤上的波压力随波高、周期的增大而增大,其水平波浪总力比同等尺度直墙少10%左右。  相似文献   

Analytical and Experimental Studies on Hydrodynamic Performance of Semi-Immersed Jarlan-Type Perforated Breakwaters   总被引：2，自引：1，他引：1  

刘勇  姚卓琳  李华军 《海洋工程》2015,29(6):793-806

The present study proposes a new semi-immersed Jarlan-type perforated breakwater including a perforated front wall, a solid rear wall, and a horizontal perforated plate connecting the lower tips of the two walls. An analytical solution is developed to estimate the hydrodynamic performance of the new breakwater. The analytical solution is confirmed by solutions for special cases, an independently developed multi-domain boundary element method solution and experimental data. Numerical examples based on the analytical solution indicate that compared with previous semi-immersed breakwaters, the new breakwater may have better wave-absorbing performance and smaller wave forces. Some useful results are presented for practical designs of semi-immersed Jarlan-type perforated breakwaters.  相似文献   

浅析高精度地图发展现状及关键技术   总被引：1，自引：0，他引：1  

杨振凯  华一新  訾璐  张政  王继伟 《测绘通报》2021,(6):54-60

随着国家对智能汽车创新发展战略任务的推进,作为其关键保障技术的高精度地图在近几年已经成为测绘等多个领域的研究重点。针对当前高精度地图综述性理论研究相对缺乏的问题,本文从高精度地图数据结构、数据生产和功能应用3个方面,对高精度地图相关的主要研究内容及现状进行阐述和总结。从数据结构层面,高精度地图描述内容可划分为静态地图数据和动态地图数据,其中静态地图数据是当前制图的重点;考虑数据生产的层次性,分别对高精度地图的生产模式、生产流程和具体的技术方法进行了分析,认为专业部门指导结合众包是数据生产的基本特征;以自动驾驶中的匹配定位和导航规划为代表,总结了高精度地图在应用方面的关键技术。最后,对高精度地图未来发展的方向进行了展望。  相似文献   

Critical conditions for natural gas charging and delineation of effective gas source rocks for tight sandstone reservoirs     

Fujie Jiang  Xiongqi Pang  Fengtao Guo  Jigang Guo 《Geological Journal》2016,51(1):113-124

Although it has been shown that the potential of tight‐sand gas resources is large, the research into the mechanisms of hydrocarbon charging of tight sandstone reservoirs has been relatively sparse. Researchers have found that there is a force balance during hydrocarbon charging, but discriminant models still have not been established. Based on the force balance conditions observed during gas migration from source rocks to tight sandstone reservoirs, a calculation formula was established. A formula for identifying effective source rocks was developed with the gas expulsion intensity as the discrimination parameter. The critical gas expulsion intensity under conditions of various burial depths, temperatures, and pressures can be obtained using the calculation formula. This method was applied in the Jurassic tight sandstone reservoirs of the eastern Kuqa Depression, Tarim Basin, and it was calculated that the critical expulsion intensity range from 6.05 × 10⁸ m³/km² to 10.07 × 10⁸ m³/km². The critical gas charging force first increases with depth and later decreases with greater depths. The distribution range of effective gas source rocks and total expelled gas volume can be determined based on this threshold. This method provides new insight into and method for predicting favourable tight‐sand gas‐bearing regions and estimating their resource potentials. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

一种新型高度地形追随坐标在GRAPES区域模式中的实现:理想试验与比较研究   总被引：1，自引：0，他引：1  

张旭  黄伟  陈葆德 《气象学报》2015,73(2):331-340

将一种新的高度地形追随坐标(Klemp坐标)引入了GRAPES区域模式,并与传统追随坐标(Gal-Chen坐标)和平缓地形追随坐标(SLEVE,Smooth Level Vertical coordinate)进行了比较。对不同坐标下气压梯度力的计算误差通过理想静止大气试验进行了评估,结果表明:与Gal-Chen坐标和SLEVE坐标相比,Klemp坐标有效地减小了气压梯度力的计算误差。理想重力波模拟试验表明,Klemp坐标下对重力波的模拟相比其他两种坐标也更接近于解析解。模式进一步采用了Mahrer气压梯度计算方案减少了计算误差,并提高了模式的精度和稳定性。实际个例试验与理想试验的结论相似。  相似文献   

不同洞口位置节能砌块隐形密框复合墙体恢复力模型研究          下载免费PDF全文

倪博文  李升才  朱永甫 《世界地震工程》2022,38(1):056-68

为研究洞口位置对节能砌块隐形密框复合墙体滞回特性的影响,对6个采用低周反复加载方式的1/2缩尺试件的试验现象及数据进行分析。基于试验结果和现有恢复力模型理论,对试验数据进行拟合分析,利用退化四折线模型和回归方法,建立节能砌块隐形密框复合墙体的四折线恢复力模型。试验结果表明:当洞口位于墙体中间时,试件滞回环愈加丰满,试件初始刚度有所增加,承载力衰减速率减小,卸载刚度退化速率变慢。通过对骨架曲线特征参数的计算,并和试验骨架曲线对比,两者吻合较好,表明该恢复力模型可以较好的反映出不同洞口位置对其滞回特性的影响,可为节能砌块隐形密框复合墙体的弹塑性分析及工程应用提供参考。  相似文献   

基于细观力学的混凝土劈拉破坏率相关特性研究     

秦川  张楚汉 《岩土力学》2010,31(12):3771-3777

提出了一种高效的混凝土细观力学预处理方法,其中包括基于背景网格的骨料投放与细观三组分的识别;建立了颗粒离散元的混凝土细观力学模型。利用该模型对不同应变率下混凝土的劈拉试验进行了数值仿真,仿真结果显示出的混凝土动力强度提高的规律以及不同应变率下混凝土的破坏模式与试验结果吻合较好。研究表明,随着应变率的提高,混凝土破坏时产生更多弥散状分布的裂纹,同时有些裂纹穿过强度较高的骨料,导致混凝土在高应变率破坏过程中消耗更多的能量,是混凝土的动力强度提高的重要原因。此外,在高应变率下,力链产生更多的分叉,空间分布的不均匀性和随机性增加,因此,在高应变率下混凝土动力强度表现出更大的离散性。  相似文献   

灌注桩后注浆单桩竖向极限承载力研究          下载免费PDF全文

刘建茂  杨子民  王连力  康宪泉 《地质找矿论丛》2010,25(4):381-386

近年来,后注浆技术得到了广泛的应用。钻孔灌注桩可大大降低建筑物的沉降,并使建筑物的沉降更加均匀,文章介绍后注浆工艺的承载力提高机理及在天津地区的几个工程实例,分析了注浆前后单桩竖向极限承载力对比情况及影响单桩竖向极限承载力的几个因素。  相似文献