【作者】 张宁霞；

【导师】 刘保健；

【作者基本信息】 长安大学 ， 岩土工程， 2014， 博士

【摘要】 涵洞是公路工程中的重要组成部分之一，在山岭重丘地区，每公里平均约有4~6道。然而涵洞工程并没有得到应有的重视，在设计时仅参考平面地形图和工程地质勘查资料，并没有重视涵洞的设计理论，忽略了涵洞结构与土体是共同工作、是超静定结构的机理，从而导致涵洞病害的产生，严重影响了高速公路的正常运营。本文依托国内某大跨径高填方涵洞，通过理论分析、数值模拟和必要的工程实例，对大跨径高填方涵洞的工作特性进行综合研究，取得了以下成果：1．目前，对于涵洞工程，公路规范中的竖向土压力为土柱压力，小于涵顶受到的实际压强，使涵洞结构处于不安全状态；同时，公路涵洞工程的地基与基础设计借助于工民建工程中基底压力小于地基承载力原则，这就导致了两个问题：一是若地基承载力不够则进行地基处理，结果是：地基处理的强度达到了，地基承载力满足了，但作用在涵顶的竖向土压力却超出土柱压强越多。二是对于涵洞工程，一般用公路设计规范计算的地基承载力会明显不够，主要是埋深的取值不对，这正是规范没有考虑涵洞工作特性的原因。本文分析后认为：要对设计规范的地基承载力公式进行修正，修正后的地基承载力会高出现行规范计算的承载力。总之，公路规范中不仅竖向土压力计算值偏小，地基承载力计算值也偏小，本文对此进行了研究并进行修正，且通过实际工程为依托进行验证。2．涉及涵洞竖向土压力有名的计算公式有二十多种，各自考虑的因素不一，且目前众多公式的适用情况比较分散，至今仍缺乏对涵洞土压力计算理论进行统一的整理归纳。本文对其进行了梳理、分析、验证，说明了各自的适用条件及优缺点，可为应用提供参考。并通过一工程实例，对现有涵洞竖向土压力计算理论与方法进行对比评述。3．涵洞与土共同作用是超静定结构，对荷载结构进行设计时，必须先应判断其属于哪种工况，才能选用合适的竖向土压力计算公式。现有的涵洞与土体的共同作用机理模型都侧重于从某一个方面对涵顶土压力进行分析，由于不同的实际工程其特点是不同的，涵体的劲度、地基刚度、埋设形式和填土性质等都对涵顶的土压力有重要的影响。针对目前现有的涵土的分析模型的不足，本文提出了“质剪弹”模型，该模型能够全面的反映涵土作用机理，能解决多数涵洞与土共同作用的力学问题。4．依托工程设计中，一方面，设计方在计算地基承载力时采用常规的方法，没有理解基础埋置深度的实质，埋深的取值不符合涵洞受力的特性。实际上，工民建中是挖基坑后埋置基础，而涵洞工程通常是修建好涵洞后在其上填埋土体，其实质是不同的。结果使公式中基础埋置深度的取值明显偏小，使计算结果不能满足地基承载力要求，设计无法通过；另一方面，设计方按照传统的理论，认为涵顶土压力等于土柱压力，以此作为设计依据。对于高填方涵洞而言，这些理论是不适用的，是错误的。如果按照涵顶实际承受的土压力来对涵洞结构进行设计，则涵洞结构的尺寸、配筋等都会明显增大，涵洞结构本身也会非常厚重、接近实体结构。这对于实际的工程从经济、实用、美观等方面来说都是不合适的。为了解决设计方面临的这一问题，本章根据课题组及国内外的众多研究，提出了“土压力调整”措施，即在涵顶一定范围内铺设EPS板。为了在施工前预先掌握“土压力调整”的结果，本文采用有限元软件对此进行了模拟，对大跨径高填土路堤下涵洞的荷载变化规律以及涵土的作用机理进行分析。为了设计完成后此涵洞工程的顺利施工，针对此涵洞工程提出了土压力调整方案实施的细则，对EPS板材料本身的要求、铺设的厚度、位置等做了详细的指导说明，对于施工的顺利开展提供了有利保障。更多还原

【Abstract】 Highway culvert is one important part of the project, in terrains area average of about4to6(Block) per kilometer. However culvert project did not get the attention it deserves, in thedesign of the reference plane only Geological Survey topographic maps and engineering data,and did not pay attention culvert design theory, ignoring the culvert structure and the soil is acommon task is statically indeterminate structure mechanism, resulting in the generation ofculvert, seriously affected the normal operation of the highway. This article relies on adomestic long-span high fill culverts, through theoretical analysis, numerical simulation andthe necessary engineering example, long-span high fill culvert operating characteristicscomprehensive study achieved the following results:1. Currently, culvert highway specification vertical earth pressure for the soil columnpressure, the pressure is less than the actual subject of the culvert, so culvert structure is in anunsafe condition; Meanwhile, foundation and foundation engineering design by means of civilengineering highway culvert engineering principles of foundation bearing capacity is less thanthe base pressure, which leads to two problems: First, it is not enough if the bearing capacityof foundation treatment, a result, the better the foundation treatment, foundation bearingcapacity to meet, but the role of the culvert top The vertical earth pressure is exceeded, themore pressure the soil column. Second, high fill large span culvert project, the foundationbearing capacity is generally calculated using the highway design specifications willobviously not enough, mainly depth values wrong, this is the specification does not considerthe operating characteristics of the culvert reasons. In this paper, after analysis: To designspecification foundation bearing capacity formula is corrected, the foundation bearingcapacity after correction will be higher than the current design bearing capacity. In short, notonly on the road specification less vertical earth pressure calculation, the foundation bearingcapacity less considered, this paper conducted a study and correct, and actual project as thebasis for verification.2. The formula involves culverts vertical earth pressure famous are20kinds of differentfactors to consider each and currently applicable scattered many formulas, it still lackstheoretical calculation of earth pressure on culverts unified finishing induction. This paper was carried out combing, analysis, verification, explains the advantages and disadvantages ofeach of the applicable conditions and can provide a reference for the application. And throughan engineering example, the existing culvert vertical earth pressure calculation theories andmethods of comparative commentary.3. Culverts and soil interaction is statically indeterminate structure, when the structure isdesigned to load, you must first determine what conditions should belong to the appropriatechoice of vertical earth pressure calculation formula. Existing common mechanism modelculverts and soil are focused on one aspect from the analysis of the culvert top soil pressure,due to the different characteristics of the actual project which is different, Han body stiffness,foundation stiffness, laying forms and Fill nature and so have an important impact on theearth pressure culvert roof. Current lack of analytical models for the existing culvert soil, thispaper presents the "quality scissors bomb" model, which can fully reflect the culvert soilmechanism of action, to solve mechanical problems most culverts and soil interaction.4. Relying on engineering design, on the one hand, the design side using conventionalmethods in calculating the bearing capacity of the foundation, there is no substantive basis forunderstanding the depth of embedment, depth values do not meet the culvert forcecharacteristics. In fact, civil engineering is embedded after digging the foundation pit, andculvert construction project is usually good after culverts landfill soil on it, and its essence isdifferent. Resulting in a formula-based embedded depth was significantly smaller values, sothe results can not satisfy the requirements of foundation bearing capacity, not by design, buton the other hand, according to the traditional square design theory that the earth pressureequal culvert top soil column pressure, that is considered to meet the design requirements. Forhigh fill culverts, these theories are not applicable, is wrong.If designers follow the actual culvert earth pressure to bear on the culvert structuredesign, the size of the culvert structures, reinforcement, etc. will be significantly increased,while the culvert structure itself will be very heavy, close to the physical structure. This worksregardless of the actual economic, practical, beautiful and so it is inappropriate. To solve thisproblem the design side facing in this chapter and in accordance with a number of domesticand international research group, proposed the "earth pressure adjustment" measures, namelythe laying of culvert EPS board in the top of a certain range. In order to advance in the pre-construction master "earth pressure adjustment" results, we use finite element software tosimulate this, load variation on the large span under high embankment culverts and culvertmechanism of soil analysis.In order to design successful completion of the construction of this culvert project,proposed for this culvert earth pressure adjustment programs implemented rules. EPS boardmaterial itself on the requirements laid thickness, position, and so do the detailed instructions.For the smooth conduct of construction provides a strong guarantee.更多还原