含砂低液限黄土冲沟高填方路基填筑质量控制

针对我省西北地区普遍存在的含砂低液限黄土的颗粒组成、物理和力学性质、压实性能等问题进行试验研究和微观理论分析,研究含砂低液限黄土的内部结构与工程特性之间的关系,研究其压实机理,并针对特殊的压实特性提出相应合理的压实度控制指标,并优化现有的路堤压实工艺,确保含砂低液限黄土作为路堤填料的压实度要求。     

Improvements to the structural condition index (SCI) for pavement structural evaluation at network level

Structural evaluation provides valuable information about the expected behaviour and response of pavements and can be used at the network level of pavement management to prioritise projects. The falling weight deflectometer (FWD) can be used to identify the beginning and end of management sections and group pavement sections with similar structural capacities. The structural condition index (SCI) was developed as a screening tool for the pavement network-level evaluation, and the FWD data are used to determine the SCI. For the successful implementation of the SCI concept at the network level, one of the critical issues is the accuracy of the index. This article evaluates the accuracy of the SCI and also discusses a concept and procedure how to improve the SCI and its algorithm for low-volume flexible pavements. A case study (Texas) illustrates that the original SCI algorithm underestimates the existing structural condition, resulting in overestimated treatments in the pavement maintenance and rehabilitation.     

Measuring hydraulic properties of geotextiles after installation damage

Since geotextiles have been progressively incorporated into coastal protection structures, the influence of installation damage on them has been the primary concern. During installation/construction, geotextiles are repeatedly subjected to high mechanical stresses which often exceed service stress. It is therefore vital to evaluate the mechanical and hydraulic damage and determine the consequences of these damages to better develop criteria for selection of suitable products. As these damages could reduce the material's mechanical strength and hydraulic efficiency, or in the severest form of damage, puncturing, would end the separation function. The properties investigated in this paper include the permittivity and apparent opening size (AOS) of geotextiles. Generally, the greater the drop energy of armour units applied to geotextiles, the greater the potential for damage. Findings show that the residual permittivity could increase significantly, 45% during installation. The preliminary design of coastal structures will be optimised as engineers and designers can better estimate the amount of damage on geotextiles upon installation.     

公路桥涵路基加固及防渗工程中注浆施工技术

总结了注浆施工技术应用中的问题及对策,结合公路桥涵路基加固情况,就注浆施工技术要点作了分析,并给出了注浆效果检验方法,以指导工程实践。     

高寒地区路基填筑施工措施

根据海公铁路扩能改造工程概况,详细介绍了工程在冬季施工时路基填筑采取的措施,从施工方案和质量控制两方面展开叙述,实践证明这些措施在冬季路基填筑施工中取得了良好效果,克服了冬季施工的困难。     

Normalized load‐deflection curves of lateral piles in homogeneous elasto‐plastic soils

Abstract

In this paper, the procedure of normalizing load‐deflection curves of lateral piles in a homogeneous elasto‐plastic soil is presented. An analytical method using subgrade reactions reveals that the normalized relation of load‐deflection exists for force, moment or combined load. The normalized curves for force and moment load fit very well with the predictions using the equations. For the combined load, the normalized curves are distributed between the force and moment load curves, so it is easy to use interpolation from a family of curves. These normalized curves provide a very convenient way for calculating the pile load or deflection in the design stage.     

谈一般土质路基的压实

结合土壤的压实特性,从机械选择、铺层厚度、含水量控制、碾压速度和遍数等方面对土质路基的压实技术进行了阐述,并介绍了路基的压实标准及检验方法,以确保土质路基的整体强度、稳定性和耐久性满足规定要求。     

煤矸石填筑路基冲击压实施工关键技术研究

煤矸石大量的堆积和自燃,给社会和环境造成了极大影响。公路建设中利用煤矸石填筑路基,节省了土方,改善了占用土地和环境污染等问题。本文以高速公路工程为背景,分析了煤矸石填筑路基施工中的冲击压实情况。     

用简单原位试验确定切线模量法的参数及 其在砂土地基非线性沉降分析中的验证

地基沉降计算一直是岩土工程研究中的热点和难点问题,其困难在于室内试验与原位岩土参数差异较大,尤其是砂土地基和结构性强的硬黏土地基,基于室内试验参数的沉降计算与实际的误差较大。基于原位压板载荷试验来确定计算参数的切线模量法能克服这个缺点,并能计算地基的非线性沉降,是地基沉降计算的一个新进步。但原位压板载荷试验相对其他试验难度大、费用高,尤其对于深层土体,难度更大。为此,利用位于美国Texas A&M University大学河滨校区砂土地基上进行的系统的岩土试验资料,通过其不同压板尺寸的载荷试验,对切线模量法应用于砂土地基非线性沉降计算的适用性进行了验证,然后进一步研究由旁压试验、静力触探等简单的原位试验确定切线模量法所需的计算参数的可行性。结果表明：切线模量法所需的计算参数由旁压试验、静力触探等简单的原位试验确定是可行的,从而为切线模量法的推广应用确定提供了更简单的方法。对推动地基设计理论的发展有较好的意义。     

中—强膨胀土地区铁路路堑基床动静态特性模型试验

为研究以中—强膨胀土为地基的高速铁路路堑基床在不同服役环境下的动静态特性,在实验室内进行1∶1大比例尺模型试验,分别对基床在干燥状态、降雨和地下水位上升3种服役环境下以4 Hz频率进行100万次激振,监测路堑基床不同位置的动态响应和变形规律。结果表明：轨道正下方位置基床范围内的动应力主要受服役环境影响,与激振次数关系不大;动应力沿深度的衰减曲线近似成二次曲线型;膨胀土路堑基床变形受服役环境的影响大于振动次数;干燥状态和降雨时,基床变形随着振动次数的增加先增大后趋于稳定,地下水位上升时,基底膨胀土膨胀变形,并引起基床产生回弹变形;基底膨胀土干缩湿胀过程中的“过程性变形差”会造成轨面标高反复变化,极大的增加线路维护工作量。