【作者】 童怀峰；

【导师】 郭院成；

【作者基本信息】 郑州大学 ， 结构工程， 2008， 博士

【摘要】 近年来,随着我国经济的快速增长,特别是加入WTO以来,物流业的发展,城市间的合作往来更加紧密,高速公路的交通流量日益增加,现在有相当一部分已不能适应交通量增长和社会发展的要求,迫切需要扩大道路通行能力,由于近距离新建高速公路,投资规模大,占用土地多,且容易造成路网分布不均,因而在现阶段我国高速公路扩建大多采用老路加宽的方案。高速公路的扩建加宽就必然涉及到新老公路的融合贯通、新老路堤的相互影响等问题,原有路堤经过多年运营,沉降已基本完成,在其边坡上进行扩建加宽,新填的土方和运营后的汽车荷载必然会引起既有路基的附加沉降,并在新老路基之间产生相对过大的差异沉降,进而会引起既有路基变形,严重时则出现路基拉裂,下沉过速等病害,将会对高速公路的正常营运带来难以估量的不良后果;同时,高速公路加宽扩建工程通常工期紧、施工场地狭窄,同时还要维持正常的交通运输,较新建高速公路具有更高的要求。因此选择经济、快速、可靠的加宽处治措施以确保现有高速公路营运安全、确保减小加宽后高速公路新旧路面的差异沉降就显得尤为重要。本文基于以上工程背景,主要研究内容如下:1.高填方路基后处理技术即投石压浆无砂砼小桩技术是一种新的地基处理技术,通过对无砂砼小桩技术的施工工艺、压力注浆、后处理机理的详细分析可知,后处理技术具有堆载预压、快速排水、排气固结、固化、竖向置换增强等综合作用机理;投石压浆无砂砼小桩复合地基由于其特殊的施工工艺,其承载力大小除与工程地质条件有关外,还与灌浆材料、灌浆压力和灌浆量、灌浆工艺及置换率有关,所以在无砂砼小桩复合地基承载力计算公式中引入参数β₁（投石压浆无砂砼小桩单桩承载力发挥系数）和β₂（桩间土承载力增强系数）;通过对无砂砼小桩复合地基桩土竖向变形协调、桩间土的应力和竖向变形的分析,解决了无砂砼小桩复合地基基于变形控制下的优化设计问题。2.高填方路基后处理技术中后处理先填土高度的确定是非常关键的一个技术环节,直接关系到后处理技术的经济和社会效果,对于不同的地质条件,采用不同的分析确定方法,当浅层含有饱和软弱土层,地基承载力较低时,采用基于统一双剪强度理论的分析方法分析确定后处理先填土高度,可以充分发挥天然地基的原有承载力,达到降低造价的目的;当地基承载力较高时,基于小坡堤稳定的分析方法可以方便地分析确定后处理先填土高度,消除了后处理之前由于填土自身稳定问题给工程带来的不良影响。3.基于高填方路基加宽时加宽填土荷载的特殊性,对各种荷载形式作用下地基土体的初始有效应力和超孔隙水压力进行了分析;对后处理技术先填土、成孔施工各阶段的固结过程进行了详细分析,得出了各阶段土体超孔隙压力和固结度的计算分析结果。4.基于统一强度理论和柱形孔扩张弹性理论,分析了无砂砼小桩注浆期间注浆压力与桩周土体的应力状态,得出了考虑中主应力影响下桩周土体处于弹性状态和弹塑性状态时注浆压力计算公式以及注浆压力与塑性开展半径的关系式;通过对桩周土体处于不同应力状态时土体注浆开裂与挤密之问的相关关系以及中主应力权系数b和初始应力p₀取不同值时注浆压力p与塑性开展半径r_c的关系进行了分析,为后处理技术注浆施工工艺的优化选择提供理论依据。5.基于高速公路双侧对称加宽的工程背景,对加宽路基不进行处理和采用先处理及后处理三种情况下,加宽填土荷载的施工对原有地基和老路路堤的变形性状的影响进行了详细的数值模拟对比分析。6.在无砂砼小桩后处理技术在路基加宽工程的应用中,通过对老路坡肩和新加宽路基坡肩位置水平及竖向变形监测结果可知,小桩后处理技术不仅能够增强新老路基之间的结合,而且能够协调新老路基之间的变形,大大减小工后沉降变形。更多还原

【Abstract】 In recent years, with the rapid growth of economic construction in our country,especially since the accession to the WTO and the development of the logistics industry, city-to-city cooperation between more closely and traffic flow of highway increasing, the considerable portion of highway has been unable to meet the demand of traffic growth and the requirements of the social development, there is an urgent need to expand the capacity of the road. Because the construction of a new highway near the old highway would cause the large-scale of investment and the use of more land, and easily lead to uneven distribution network, the old road widening programme were adopted by the most of China’s highway expansion projects at the present stageHighway expansion will inevitably involve the integration and link of old and new highway, and mutual influence of old and new embankments and other issues, After years of operating the existing embankment, the settlement has been completed, in its wider expansion on the slope, reclamation of the earth and the operation of the vehicle load is bound to cause additional settlement of the existing roadbed, and the relatively large difference settlement between in the new and old roadbed, then not only will cause deformation of roadbed, while there is a serious road-Kira, have been sinking fast, and other diseases, the immeasurable negative consequences will bring to the normal operation of highway; At the same time, the construction time of widening expansion projects of highway is normally tight, and the construction site is narrow, while also maintaining the normal transport, there are higher demands compared to the construction of a new highway. So it appears to be particularly important that to choose the economic, fast and reliable treatment measures in widening the existing highway to ensure the security operations of the existing highway and the reduceing of the differential settlement between the old and new hughway pavement after widening. Based on the above background of the project, the main contents of the study are listed as follows:1. The post-processing technology of small non-sand concrete pile is a new processing technology of thick filling area, through the detailed analysis of the construction technology and the pressure grouting and the post-processing mechanism of small non-sand concrete pile technology, we can see the post-processing technology have preloading, rapid drainage, exhaust consolidation, curing, the vertical displacement, and so on a comprehensive mechanism; Composite foundation with small non-sand concrete pile because of its unique construction process, its bearing capacity related in addition to the engineering and geological conditions, but also to filling materials, grouting and pressure grouting, grouting process and the replacement rate, so the parametersβ₁ （pile capacity to play a factor of small non-sand concretepile） andβ₁ （enhancing factor of bearing capacity of inter-pile soil） were introduced inthe bearing capacity formula of composite foundation with small non-sand concrete pile; Through the analysis of the vertical deformation coordination of the pile-soil, and the soil stress and deformation between the piles of composite foundation with small non-sand concrete pile, the optimal design based on the deformation control was solved2. First filling height is a key technical parameters in the post-processing technology of thick filling area, it direct related the economic and social effects of post-processing technology, so different methods of analysis were used for different geological conditions, when the weak saturated with shallow soil, bearing capacity is low, the calculation methods of first filling height based on the twin shear unified strength theory is discussed, which can give full play to the natural foundation of the original capacity, to achieve the purpose of reducing costs; When bearing capacity is high, the methods of analysis based on the stability of embankment can easily determined the first filling height, which eliminated the adverse effects due to filling its own stability before post-processing.3. Based on the particularity of widening filling load of thick filling area, analysis of the initial effective stress and ultra-pore water pressure of soil under various forms of loads were carried out; results of pore water pressure and degree of consolidation of soil were obtained in various stages based on the detail analysis of consolidation process for the first filling and construction of hole in the post-processing technology.4. Based on the expansion elastic theory of cylindrical cavity and the twin shear unified strength theory, analysis of stress state of soil around the pile and grouting pressure of small non-sand concrete pile is given, grouting pressure is obtained in the elastic limit state and elastic-plastic state of soil around the pile considered the intermediate principal stress, and the relationship is obtained between the grouting pressure and the plastic radius; When the soil around the pile is in different stress state, the correlativity of crack and densification of grouting is analyzed, and the relationship between the grouting pressure p and the plastic radius r_p is discussed withthe right coefficient b of the intermediate principal stress and initial press p₀ underdifferent value, which has provided theoretical basis for optimazation of grouting construction technology of small non-sand concrete pile.5. Based on the engineering background of the widening bilateral symmetry of highway, a detailed comparative analysis of the influence of The characters of deformation of the original foundation and the old embankment with the construction of the widening filling load on numerical simulation is carried out considering both cases that widening embankment is not used for processing and use of pre-processing and post-processing.6. In the applications of the post-processing technology in the road widening project, through the level and vertical deformation monitoring results of the old sloping shoulders and widening road shoulders slope position, we can see the post-processing technology not only can enhance the combination between the old and new embankment, but also can coordinate deformation between the old and new roadbed, significantly reduce the settlement after construction.更多还原