摘要 旧路加宽改造可利用有限的建设资金提高既有道路的等级，随着国民经济的快速发展，旧路加宽改造工程越来越多。旧路加宽改造后，由于新旧路基在土质、结构、强度和固结时间等方面的差异，必将在新旧路基间产生沉降与变形以及刚度的差异，此种差异是导致路面沿纵向开裂等结构性损坏的最直接、最重要的原因之一。因此，旧路加宽综合处治技术的关键是：一方面在设计和施工时采取有效的处治措施来减小这种差异；另一方面通过路面结构层的优化设计来改善层底产生脱空时路面结构的受力状态，以保证路面结构在使用期间不会因新旧路基间的这种差异而产生结构性的破坏。 路基经加宽改造后，新旧路基间沉降与变形的差异是必然存在的，运用相关的分析理论与计算方法可对新旧路基间的沉降与变形差异的大小和分布形态进行研究。对于产生层底脱空的路面结构，可采用弹性半空间地基的三维应力分析方法进行分析。三维应力分析方法可考虑半空间体上下结构层之间既非完全连续，又非完全光滑的接触状态，且可较好地运用弹性薄膜单元来模拟分析土工合成材料的加筋作用。 基于层底脱空的路面结构分析结果表明：当层底脱空深度大于2．0锄的临界值时，脱空深度的变化对结构受力的影响甚微；而脱空范围的变化对路面结构响应的影响非常明显，脱空范围越大结构受力越不利。路面表面变形和基层层底拉应力是结构响应分析的主要指标，而以基层层底拉应力作为旧路加宽路面设计的控制指标更为合适，由此而计算得加宽路基层底脱空范围的临界值为2.0m。通过结构层参数变化对路面结构响应的敏感性分析，发现基层厚度是最主要的影响冈素。 室内模型试验和现场试验路的测试分析结果表明，土工合成材料加筋可提高路基的回弹模量，减小路基的不均匀变形，从而可有效地扩散上覆荷载的传递，阻止和延缓路面的破坏。在室内外试验研究成果的基础上，提出了加宽路基处治的最佳方案——在二灰、粉煤灰等轻质材料路堤中加铺土工合成材料加筋的综合处治措施。 关键词：】旧路加宽；综合处治；沉降与变形差异；刚度差异；三维有限元分析法；弹性薄膜单元；路面结构分析；脱空模式；土工合成材料加筋；轻质材料路堤。 ABSTRACT The road grade call been advanced by widening of the old road，using the limited funds．So it is more and more to widening of the old road，along with the developraent of national economy．There are difference of settlement and deformation，and rigidity between the new and old subgrade，because of the difference between soil character、structure、strength and the time of concrefion，for widening of the old road． It is one of the most indirect and important reasons that will lead structure destroy as longitudinal crazing of pavement．On the basis of these，the key technology of synthetical disposal has two hands．On the one hand，the difference between the new and old subgrade will be reduced by the effective disposal ways，in the process of design and construction．On the other hand， in order to assure the road structure doesn’t been destroyed by the difference．，through optimizing design to improve the bearing-force status of pavement structure，for hoHowing in the basis of layer． It is certain that there being difference of settlement and deformation between the Hew and old subgrade，so we can study the size and distributing form of the difference，by using the analysis theory and calculating method．It is can been analyzed by using the three-dimensional stress analysis method of elastic semi—space foundation，for the pavement structure of hoflowing in the basis of layer．We can not only consider the non-absolute continuous contact status between the upper and under structure layers，but also consider the non-absolute slick contact status．So we can successfully analyze the reinforce action of geofabric．by using the model of elastic film cell． When the depth of the subbase hollowing exceed 2.0cm,the bearing—force status of road structure has little varies，so the limited depth is 2.0cm．But it does been extraordinary notability effected by the scope vary of hollowing，the scope of hollowing is bigger,the bearing•force status of road structure is worse．The result of there-dimensional fmite element method analysis indicates，the tension stress of subbase basis and the distortion of road surface are the most important analysis index．the tension stress of subbase basis caIl been used as control index in the analysis of responsibility of road structure for widening of the old road，so the limited scope is 2．0nL Through the sensitivity analysis of the responsibility of road slructure，by the varies of structure layers’ parameter,we can found that the depth of subbase is the most important effect factor． Because of the modulus of subgrade being improved and the different deformation being reduced，so the breakage of pavement can been postponed，by the reinforce action of geofabnc．On the basis of inner and field test result，the best disposal plan for widening of the old road has been put forward，it is the synthetical disposal ways of rolling out geofabric in the embankment，which is filled by two kind ashes、fly ash，etc light material．Not only it is credibility and availability on technology,but also it has favourable benefits of economy and society．. Key Words: Widening of the old road；Synthetical disposal；Difference of settlement and deformation；Difference of rigidity；There-dimensional fmite element method；Pavement slructure analysis；Pattern of hollowing；Reinforce action by geofabfic；Light material embankment． |
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