路基工程中的石方路基质量控制

结合工程实际,通过对石方路基试验段的施工质量的控制,总结出了石方路基工程的质量控制标准:当石方填料最大粒径≤47.5 cm,石块含量超过总量的75%,选用50 t振动压路机,松铺厚度不大于50cm,碾压遍数不少于8遍,沉降量指标≤5 mm时,可视为石方路基的压实质量合格。     

新型轻质材料填筑路堤的试验与稳定分析

通过室内抗压、抗拉及抗剪强度试验,说明了轻型混凝土可作为一种新型的路堤填筑材料,轻型混凝土的容重仅为压实土的1／3到1／2,其抗压强度,抗拉强度,抗剪强度比压实土高得多,压缩性很小。工程实例表明它在软基上筑堤具有广阔的应用前景。     

浅谈深层搅拌水泥土防渗墙在堤防工程中的应用

文章主要从深层搅拌防渗墙的原理、深层搅拌桩的施工控制参数、施工操作要点、施工质量检测及施工所存在的问题等方面进行阐述,以供参考。     

山区高速公路高填路基病害分析及治理

分析了高填路基病害、成因,并对其防治措施进行了探讨。     

山区高速公路门架式标志牌视认特性研究

为了研究山区高速公路不同路基形式下门架式标志牌处的驾驶人眼动特征,通过多条高速公路的实车试验,利用Smart Eyepro5.7眼动仪采集和记录驾驶人的眼动参数和注视行为。通过对行车录像的逐帧分解,得到了路堤和路堑的段数,并分别筛选出路堤和路堑的门架式标志牌路段数。采用视野平面法划分驾驶人行车视域,分别统计路堤、路堑和门架式标志牌各视域的注视分布情况;并对应驾驶人的眼动数据进行视觉适宜性和敏感性分析。结果表明:位于不同路基形式上,门架式标志对驾驶人眼动特征的影响具有显著性差异。在路堤段的视觉适宜性要高于路堑段,而路堑段的视觉敏感性要高于路堤段;路堤和路堑的右侧近处是驾驶人视觉较为敏感的区域;路堑段右侧近处的信息量较大,而路堤段右侧远处的信息量较大;道路前方是最敏感区域,信息量也最大。门架式标志牌是驾驶人的视觉适宜和敏感目标,驾驶人视点明显抬高,前方上侧是敏感区域。在同等条件下,门架式标志牌宜设置在路堑段。     

低路堤软土地基在交通荷载作用下的动力特性试验研究

设计并制作了低路堤软黏土地基模型。测试了软黏土地基在交通荷载不同强度、不同频率下的动土压力和孔隙水压力;以及土压力和孔隙水压力随深度的变化。获得了低路堤软粘土地基在交通荷载作用下的动力特性发展规律。研究表明:在交通荷载循环作用下,无论荷载强度、荷载频率的大小,软黏土地基的土压力和孔压都是随着埋深的增加而呈衰减趋势。随着荷载频率的增加,土压和孔压的波动变化明显加剧,但压力值并不是随着荷载频率的增加而简单的增长或减小;随着荷载强度的加大,某一深度处土压力受到的最值变化不是很明显,而孔隙水压力却显著的发生了变化。     

低承台桥台桩基侧向受力性状试验与数值分析

基于现场测试结果,采用三维有限元技术分析低承台桥台桩基在台后路基填土过程中桩基沉降、桩身弯矩、桩顶水平变形、桩身剪力和桩侧附加水平挤压力随台后填土荷载增加的变化规律.研究结果表明:计算结果与实测结果吻合较好:桩顶水平变形和桩身最大弯矩随填土荷载的增加近似呈线性增加:深度方向20m范围内,桩身剪力图呈“S”型,桩侧附加水平挤压力图呈抛物线型.低承台桥台桩基力学模型等同于桩项和桩端嵌入一定深度、具有一定变位的超静定梁结构.本文所得结论可以为桥台桩基的设计和施工提供参考.     

山区高速公路构造物占地研究

根据山区土地资源缺乏、公路构造物为永久性占地的特点,以湖南省吉首至怀化、安化至邵阳高速公路为例,对采用路基方案和对应的桥梁、隧道、路基支挡物方案进行了比较,分析了山区高速公路桥梁、隧道、路基支挡结构等构造物的占地特点,对山区高速公路构造物方案的确定具有一定的参考意义。     

Numerical Analysis for Temperature Characteristics of Open Boundary Crushed-rock Embankment on Qinghai-Tibet Railway

At present, in order to protect the stability of permafrost beneath embankment, the crushed-rock embankment, as a new type of embankment structure, has widely been used in the construction of Qinghai- Tibet Railway. Its crushed-rock layer is almost open in tow bilateral boundaries and closed at top and bottom, and air can flow into/out of the ballast layer and crushed-rock layer. Therefore, the convection and transfer heat patterns are very complicated in the ballast layer and crushed-rock layer of the embankment, which are regarded as porous media. In this paper, based on the wind, temperature and geology conditions of Qinghai- Tibet Plateau, a numerical approach of the unsteady two-dimensional continuity, momentum （non-Darcy flow） and energy equations of heat convection for incompressible fluid in porous media is provide to analyse the velocity and temperature characteristics of the crushed-rock embankment with different embankment heights under open boundary condition for the coming 50 years. The calculated results indicate that, due to the influence of the external wind, the convective heat transfer mainly relies on the forced convection in the open crushed-rock emban kment. Even if the air temperature will be wanned up by 2.6℃ in the coming 50 years, it still has a better cooling effect on the underlying soils and a low temperature frozen-soil core is formed in the permafrost below it if the embankment is constructed in the regions whose present mean annual air temperature is - 4.0℃. Furthermore, the cooling effect of high crushed-rock embankment is better than that of low embankment. This results from the fact that the wider bottom of high emban kment has a more influence dimension on the underlying frozen soil. However, cardinal winds on Qinghai-Tibet Plateau disturb its convection pattern, so that an asymmetric temperature distribution occurs under high embankment and it is possible to induce a transverse uneven deformation of emban kment, but no similar situation occurs under low embankment. This asymmetric temperature field problem should be considered when crushed-rock emban kment is designed and constructed.     

山区高速公路高路堤加筋土挡土墙的设计

加筋土挡土墙是20多年来我国公路工程中广泛采用的挡土墙新技术.本文就楚(雄)——大(理)线高路堤加筋土挡墙工程为实例,以设计方案比选、拉筋设计拉筋抗拔稳定检算以及面板和其他构造的设计为重点,并对筋土之间的摩擦系数取值方法进行讨论,进一步拓展了加筋土技术在山区高等级公路上的应用范围.