Influence of filling velocity on stability of subgrade with marine soft soil

Filling velocity and thickness of soft layer are major factors affecting subgrade stability according to an example study by means of finite element stress method (FESM). A case is studied and shows that the subgrade was slided because of excessive filling velocity. To determine a reasonable filling velocity is a key problem to a subgrade with marine soft soil.     

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Settlement patterns of mountainous half-filled and half-cut widened subgrade with retaining wall

The settlement of widened highway subgrade in mountainous area is not only affected by the interaction between new and existing subgrade, but also seriously restricted by the external retaining wall. Based on the practical engineering of half-filled and half-cut widened mountainous highway subgrade with external balance weight retaining wall(BWRW), a sophisticated finite element numerical model is established. The evolution law of subgrade settlement is revealed during the whole process of new subgrade filling and BWRW inclination after construction. The settlement component of subgrade is clarified considering whether the existing pavement continues to be used. The results show that the additional settlement caused by the BWRW inclination after construction cannot be ignored in the widening and reconstruction of mountainous highway subgrade. In addition, pursuant to the comprehensive design of subgrade and pavement, the component of subgrade settlement should be determined according to whether the existing pavement continues to be used, while considering the influence of BWRW inclination after construction. When the existing pavement continues to be used, the settlement of the existing subgrade is caused by the new subgrade filling and the BWRW inclination after construction. On the contrary, the settlement is only caused by the BWRW inclination after construction.     

土工格室加固风积沙路基不同深度动力响应试验研究

风积沙路基的处理一直是沙漠公路建设面临的难题, 土工格室加固方法可为沙漠公路建设提供一条新路径, 结合S21线(乌鲁木齐-阿勒泰)沙漠公路路基现场试验, 研究不同路基深度动力响应特征, 对土工格室加固风积沙性能探究具有重要的价值及意义。结果表明: ①测试车速对路基不同深度处动应力、动加速度和动速度的时程曲线波动性影响较大, 且提高车速时, 动速度峰值、动加速度峰值和动应力峰值都出现了明显的增加; ②随着路基层深度的不断增加, 动速度幅值、动加速度幅值和动应力幅值均呈现出逐渐衰减的趋势, 其中在土工格室加固风积沙层衰减幅度最大; ③沿路基横断面水平方向上, 动速度幅值、动加速度幅值和动应力幅值均呈指数型衰减的趋势, 距振动源水平距离为5 m时, 其幅值衰减至10%左右, 可将此水平范围作为工程设计参考值。      

Wave-electric field coupling imaging diagnostic method for filled subgrade

Thick earth-rock filled embankment of large earthwork volume often occurs during the construction of expressways in mountainous and hilly areas. The compaction quality of earth-rock filled subgrade will directly affect the settlement deformation and stability of the embankment after filled. Therefore, effective evaluation on the compaction quality of the earth-rock filled subgrade is an unsolved critical technical issue to control the construction quality of highway engineering. Based on the wave propagation and electrical resistivity characteristics of the earth and rock fillings, a theoretical model of the compaction quality detection by wave-electric field coupling imaging diagnostic method was established. Then, two filled subgrade models containing cavities and heterogeneous bodies respectively were make separately, and by the wave velocity testing and electrical resistivity testing, the wave-electric field coupling imaging diagnostic method was applied to these two model. The result shows that it is feasible to use the wave testing technique and the electrical resistivity testing technique for a diagnostic test of the subgrade compaction quality. Based on the abnormal areas reflected by the wave velocity imaging and electrical resistivity imaging results, we are able to analyze the scope and site of distress but not able to quantitatively evaluate the subgrade compaction quality. We can accurately qualitatively analyze the subgrade compaction quality based on the wave-electric field coupling calculation model of fill subgrade quality proposed by this paper.     

降水强夯结构填石处理大面积软弱粉土地基试验研究

浙江省粉土、砂土分布广泛,但使用强夯法处理软弱粉土地基鲜见报道。通过某工程降水强夯结构镇石处理软弱粉土地基的试验研究,笔者认为用该方法处理大面积浅层粉土地基可取得良好的效果,具有很好的社会和经济效益。     

阿博高速公路软土地基沉降监测分析

沉降观测是验证软土地基设计、指导施工的重要手段,对阿荣旗至博克图高速公路K42+400～K42+500段软土地基处理后现场沉降观测结果及差异沉降量进行分析,表明沉降主要发生在集中填筑期内,沿路基横断面沉降量的分布是不均匀的;验证了采用砂垫层+土工格栅法处理软土地基对减小横向差异沉降和提高地基承载力效果良好。     

采空区残余倾斜变形对路基稳定性的影响分析与评价

地下开采导致的地表残余倾斜对采空区公路路基的稳定性有重要影响。针对采空区公路路基的稳定性评价,笔者提出了基于概率积分法和Knothe时间函数的地表残余倾斜的计算方法,分析了路基稳定性的条分法计算原理及残余倾斜对路基稳定性的影响机理,推导了基于解析法的路基最不利滑动面计算公式,使用C#语言编制了路基稳定性系数计算软件,并通过工程实例,对提出的方法和软件进行了验证,分析了地表残余倾斜、路基边坡坡率对路基稳定性的影响。     

风场反演中距离圈上速度退模糊方法研究

在深入分析速度模糊的特点后,根据在距离圈上不模糊点到模糊点的不连续性,以及对模糊跳变处风速差和最大不模糊速度间关系的判定,从零方位开始在距离圈上逐点进行速度模糊的判定,并引入模糊标记的形式以确定退模糊处理的区间.然后通过实例分析,证明了方法的可用性和正确性.最后利用经过该方法处理的低仰角基本速度资料成功反演了雷达风场.     

瑞雷面波在灌浆加固路基检测中的应用

瑞雷面波在灌浆加固路基检测中 ,既可利用面波波速等值线断面发现可能存在的软弱部位 ,在三维空间上宏观评价灌浆加固效果 ,还可结合少量动力触探 ,间接计算路基承载力。文章从工程实例出发 ,着重探讨了实际工程应用中路基加固效果的宏观评价及触探击数与波速回归分析中的抽样问题     

黄河三角洲地区砂土路基液化机理探讨及处置

从砂土路基液化机理人手,结合黄河三角洲地区地基土工程地质特征,对该地区路基砂土液化做现场振动试验,找出影响砂土路基液化的影响因素,主要内因有土体的密实度、含水量和土体中是否存在软弱区;主要外因有荷载的大小、作用时间和荷载频率。并针对砂土液化的内外因,结合青银高速公路强夯处理案例展开分析,提出了处理方法。     

基于LoRa的铁路路基沉降数据采集系统设计

设计一套铁路路基沉降数据自动化采集系统,采用静力水准仪作为铁路路基沉降数据的采集单元,利用LoRa无线通信技术,选用低功耗STM8系列单片机和SX1278收发器,在IAR环境下移植Contiki操作系统及其自带的Rime协议栈,完成Mesh网络的多跳传输。将采集到的铁路路基沉降数据形成可视化监测界面,实现现有铁路路基沉降数据远距离、低功耗、可靠的无线传输。     

基于球谐变换的GERD水库形变预测

提出一种基于球谐变换预测GERD水库蓄水过程中引起的地表形变的新方法。首先假定GERD水库分别在5 a、10 a、15 a间被注满,利用SRTM-DEM数据求取蓄水过程中每月水库的面积、体积和平均水高。经球谐展开后计算对应蓄水过程中引起的地表形变,并通过提高最大谐波度的上限来增加结果的精确度。3种蓄水策略下引起的垂向位移速率分别约为11.8 mm/a、5.9 mm/a、3.9 mm/a;引发的东向和西向位移速率分别约为1.8 mm/a和1.4 mm/a、0.9 mm/a和0.7 mm/a、0.6 mm/a和0.4 mm/a;引发的南向和北向位移速率分别约为2.6 mm/a和4.4 mm/a、1.3 mm/a和2.2 mm/a、0.8 mm/a和1.5 mm/a。     

某一级公路路基填土膨胀性试验

通过对某一级公路路基填土的天然含水量、液限、塑限、颗粒组成、矿物成分、自由膨胀率、胀缩总率等试验研究,运用塑性图,并综合各项指标对路基填土的膨胀性做了评价。结果认为,此路基填土为高液限和塑限的淤泥质软土,天然状态下具有弱膨胀性。通过对路基填土的击实试验和承载比试验表明,填土压实之后具有一定的膨胀性,在含水量变化差异性影响下的胀缩变形可能导致路基开裂。     

Dynamic behaviour of weathered red mudstone in Sichuan (China) under triaxial cyclic loading

The construction of a high-speed railway (HSR) in Southwest China is being hindered by a severe shortage of high-quality subgrade materials. However, red mudstone is widely distributed in the Sichuan Basin of China. The ability to use weathered red mudstone (WRM) to fill subgrade beds by controlling its critical stress and cumulative strain would enable substantial savings in project investments and mitigate damage to the ecological environment. To better understand the dynamic behaviour of WRM, both monotonic and cyclic triaxial tests were performed. The evolution of the cumulative strain vs. increased loading cycles was measured. The influences of confining pressure and loading cycles on the dynamic modulus, damping ratio, critical cyclic stress ratio (CSR), and dynamic stress level (DSL) were investigated. The relationship between the CSR and loading cycles under different failure strain criteria (0.1%-1.0%) was analysed. The prediction model of cumulative strain was also evaluated. The results indicated that the shear strength of WRM sufficiently meets the static strength requirements of subgrade. The critical dynamic stress of WRM can thus satisfy the dynamic stress-bearing requirement of the HSR subgrade. The critical CSR decreases and displays a power function with increasing confining pressure. As the confining pressure increases, the DSL remains relatively stable, ranging between 0.153 and 0.163. Furthermore, the relationship between the dynamic strength and loading cycles required to cause failure was established. Finally, a newly developed model for determining cumulative strain was established. A prediction exercise showed that the model is in good agreement with the experimental data.     

岩坡稳定性优势面分析法--以太湖度假区休体公园渔洋山边坡为例

运用优势面理论层次分析法。确定岩坡的控稳优势面．通过对太湖度假区休体公园渔洋山边坡的研究得出F1和软弱夹层是控稳优势面。通过优势面组合分析．得出4组优势分离体。其中F1、软弱夹层和边坡临空面组合为试算安全系数最小优势分离体。最后用Sarma法进行稳定性计算．得出各种优势分离体组合模型在考虑地下水和地震加速度为0．15g的情况下均是不稳定的。结果表明，采用层次分析法对岩坡稳定性进行评价的方法是可行的。     

Variation characteristics of temperature and moisture content of seasonal frozen soil during freezing process in Changchun, China

In China, seasonal frozen soil is widely distributed. The freezing damage of subgrade soil in Jilin Province has been one of major engineering geological problems troubling the safety of road, in which some common damage phenomena, such as frost heave, subsidence deformation and frost boiling, are all caused bywater translocation. Aiming at the phenomenon, the changes of moisture content of seasonal frozen soil in Changchun City are mainly studied by long-term field observation and indoor testing of physical properties under different conditions, and then the variation characteristics of moisture content in soil under different compactness and temperature conditions are realized. The results show that the increasing section of moisture content and negative temperature section all lie in 0.0-1.0 m of subgrade. Both lowest air and earth temperature occur in January to February, and the most negative temperature ranges from -7 ℃ to -10 ℃.     

蜀南地区茅口组古岩溶识别标志及储层预测

为预测蜀南地区茅口组储层,通过地质、钻井与岩心观察,地震及测井、地化指标分析等方法确定古岩溶发育状况,结合生产测试资料分析古岩溶储层在地震和测井上的响应特征.结果表明:该区主要储集空间类型为裂缝—溶洞型;储层地震响应总体表现为地震波的异常反射、相干剖面的不连续性及速度反演出现低速区;测井响应表现为深、浅侧向电阻率降低且出现正差异,密度减小,中子孔隙度和声波时差增大,而井径和自然伽马曲线的变化受空隙充填控制.该结果对该区储层预测及油气勘探具有指导意义.     

新一代天气雷达资料图像产品的生成方法

介绍了新一代天气雷达产品显示、以通用格式(BMP为例)自动保存图像文件、图像说明信息中文化的技术方法.重点对雷达产品显示资料处理中扇区填充的两种方法(屏幕坐标反查法和线段填充法)及其技术差别进行了比较分析.结果表明,屏幕坐标反查法较线段填充法原理简单,但计算复杂,对数据资料要求严格,在实际应用中易出现较大误差.     

软交换体系下VOIP的呼叫路由设计与实现

软交换是下一代网络呼叫与控制的中心，呼叫路由在软交换体系中占据着至关重要的位置。首先介绍了软交换网络的体系结构，接着说明了呼叫路由在软交换体系结构中的位置，最后，介绍了软交换体系下VOIP呼叫路由模块的设计与实现。