1、本 科 毕 业 设 计 （ 论 文 ） 外 文 翻 译系别： 工程技术系 专业： 土木工程 姓名： 学号： 译文公路工程路基施工的质量问题探析1 公路路基常见病因分析1 路基沉陷路基沉陷出现的原因主要有：填方路基由于压实不足而下沉；桥涵通道等构造物与路基衔接处由于所用材料不当或碾压时比较困难而无法充分压实，造成路基逐步下沉；软土地基未加处置或方法不妥当造成路基沉降。目前，修建高速公路，建设周期一般较短，路基没有足够的自然沉降时间，但是因赶工期在未自然沉降充分的路基上修建路面，路基的沉降也会反映到路面之上；路基施工时，土壤含水量过大，填土无法达到规范要求的压密度，从而给路基留下沉降的隐患。2 纵
2、向裂缝路基起始填筑宽度不够，到填至一定高度时经检查才发现填土不够宽，或中线偏位，进行填补镶边，在镶边时，又没有按规定挖台阶和由下而上的分层填筑碾压，造成工程竣工后镶边下沉，产生纵向裂缝；靖淤不到位，在清除植被或软基清挖时，在左边还有 12m 宽未清到，或堆放的淤泥尚未完全运到路外，就进行填土施工致使路基边缘下沉，产生纵向裂缝；半填半挖路段的路基，在填挖交界处未按规定挖台阶进行分层填筑压实，也易产生纵向裂缝；路基压实不到位，致使产生纵向裂缝，在路基施工中，应适当加宽填土，一般每边需加宽 50cm。2 公路路基施工的技术要求 1 级配砂砾垫层技术要求级配砂砾是路面垫层较好的主要材料，但砂砾本身的质
3、量优劣直接影响到垫层的作用及路面整体的工程质量，所以监理工程师应掌握对砂砾的技术要求，控制级配砂砾垫工程质量。这些技术要求包括：级配砂砾中砾石的压碎值应小于 30。砾石含量 055cm 的颗粒不得少于 50，最大颗粒不得大 6cm，级配砂砾中 0.074ram 的粉料数量不应大于 7，且塑性指数不应大于 6，鉴于级配砂砾垫层的强度主要与颗粒级配和压实有关，所以对级配砂砾的级配应有所要求。2 级配砂砾垫层的施工工艺级配砂砾垫层的施工可以分为碾压路槽、运输摊平、整形洒水碾压和初期养护等五个工序。级配砂砾是一种松散材料，为防止遭到行车破坏，监理工程师应提醒施工单位在进行施工组织计划时，要半幅通车半幅
4、施工方法，避免因施工造成行车混乱，使级配砂砾垫层的表面松散、平整度差和延长工期。3 水泥稳定砂砾基层根据施工方法又可以分为厂拌法和路拌法两种形式。底基层可采用路拌法，上基层可采用厂拌法。水泥稳定砂砾作为高等级公路路面的基层，是路面结构中的重要组成部分，关系到路面整体强度的高低和能否保证在路面设计周期内正常使用。4 水泥稳定砂砾基层的施工工艺水泥稳定砂砾基层的施工工艺有两种。路拌法施工水泥稳定砂砾基层，工序分为：初平砂砾料、洒水闷料、摆放水泥、摊平水泥、机械拌合、整型找平、碾压成型洒水养生。厂拌法施工水泥稳定砂砾基层，工序分为砂砾备料、水泥剂量、加水拌和、运料上路、摊铺碾压和洒水养生等。5 公路
5、路基的级配砂砾垫层路基复查，建立工程师在级配砂砾垫层施工前，必须对已竣工的路基进行复查验收，并向路面施工单位进行组织交接手续，交接手续应由驻地监理工程师组织，由路基、路面两个施工单位的领导和技术负责人参加，路基竣工后，由路基施工单位进行自检路基自检报告；材料试验，路面施工单位必须向监理工程师提交关于级配砂砾的各项材料试验。砂砾颗粒筛选试验，平均每半公里监理工程师在施工段上取料，送交监理工程师审查，满足级配砂砾的技术要求后，路段上的级配砂砾方可使用，砂砾容量试验，重型标准实验室。求得最佳含水量及最大密实度。3 路基施工技术措施1 路基质量控制在公路路基结构设计中土基的回弹模量影响结构层。路基上的
6、控制，压实度控制保证土的最佳含水量，强度控制路基工程。2 水破坏的控制水对公路路基使用性能的影响较大，它降低路基的强度，特别是夏天高温天气，雨水渗入整体道床。形成高温水，在行车荷载作用下，碎石剥落下来，两者分离，在行车作用下形成坑涧，表层施工按防水层处理，使水进人不到结构层内部，从而避免出现这样的破坏。3 裂缝的防治公路通常采用整体道床，整体道床裂缝的种类基本上可以分为两大类，基层开裂所形成的反射裂缝和面层自身产生的温缩裂缝，这是第一类属于非荷载裂缝：另一方类是行车荷载反复作用而产生的裂缝，它是由于整体道床基层承受的拉应力超出其抗弯强度而产生的网状不规则的裂缝，这要在设计时充分考虑。施工时控制
7、好质量就是为了解决第一类裂缝。整体道床基层裂缝的控制。选择收缩性小的水泥稳定类结构做基层，施工时要考虑到水泥类稳定材料产生裂缝的机理。整体道床面层裂缝的防治。沥青整体道床非荷载裂缝是低温和疲劳裂缝总和。它与沥青的品质有关，主要是沥青的温度敏感性和针入度，国内外多项试验表明，针人度指标越高，温度敏感性越低。公路的路基质量对公路的使用性能影响较大，因此在进行路基施工时严格按照规范要求进行，针对不同的路基项目采取不同的具体措施。原文Highway engineering roadbed constructionquality problem explore analysisOglesby CH, H
8、icks RG. HIGHWAY ENGINEERING. 4TH EDITIONM. Chichester, Sussex England:Baffins Lane. 1992Abstract: the roadbed is the highway foundation, foundation, it is a crucial road portion of tissue. Roadbed construction good ring, directly affect the road usage life, also related to the subsequent repair deg
9、ree and time. This article from the highway roadbed common etiology analyses proceed with, put forward the roadbed construction technology requirement, elaborated the method for Subgrade construction.Key words: highway roadbed construction quality and technical measuresThe roadbed is the basis of th
10、e road, under the vehicle load, the project has the following characteristics: engineering amount big, labor intensive, involve wide, investment is high. Subgrade engineering quality, directly affects the quality of highway, passenger comfort and normal traffic. On the quality of roadbed of Highway
11、Disease of many influence factors, problems also occur frequently, but most of them or by the construction quality problems caused by. A common etiology analysis, highway roadbed:1 roadbed subsidence. Roadbed subsidence appears the reason mainly has: Fill Subgrade due to inadequate compaction and su
12、bsidence; bridge and culvert channel structure and roadbed linking-up office since the materials used improperly or when rolling the difficult and cannot be fully compacted, causing gradual subsidence of soft soil roadbed; without disposal or method is not properly cause of subgrade settlement. At p
13、resent, highway, construction cycle is short, not enough natural subgrade settlement time, but due to rush deadlines without natural subsidence of roadbed pavement fully built, the settlement of the roadbed are reflected onto the pavement; roadbed construction, soil moisture content is too large, ca
14、nnot meet the requirements of specification of pressure filling density, thereby subgrade settlement to leave hidden trouble.The 2 longitudinal crack. Initial filling roadbed width is insufficient, to fill in to a certain height through the examination found that fill is not wide enough, or midline
15、deviation, to fill the edge, in the band, and was required to dig step and a bottom-up hierarchical placement and compaction, caused after the completion of the project band sinking, the longitudinal crack; Jing and does not reach the designated position, in the clear vegetation or soft foundation e
16、xcavating, on the left and 1 2m wide open to, or stacking of silt has not yet been completely transported to the road, on the construction of fill subgrade subsidence due to edge, the longitudinal crack; Semi-excavating section of the roadbed, in the fill and excavation junction fails to dig the ben
17、ch for the layered filling compaction, but also easy to produce longitudinal crack; roadbed compaction is not in place, resulting in the longitudinal crack, in the roadbed construction, should be widened properly fill, general every edge need broaden 50cm. In two, the highway roadbed construction te
18、chnology requirements1 graded sand gravel cushion technical requirements. Graded gravel road cushion is better the main material, but the gravel itself quality affects directly the cushion effect and the whole road engineering quality, so the supervision engineers should master the technical require
19、ments of gravel, control of graded sand gravel cushion engineering quality. These technical requirements include: graded gravel gravel crushing value should be less than 30%. 0.5 - 5cm particles of gravel content shall not be less than 50%, the largest particles shall be not more than 6cm, graded gr
20、avel 0.074ram powder quantity should not be greater than 7%, and plasticity index should not be greater than 6, in view of graded sand gravel cushion between the intensity of particle gradation and compaction, so the graded gravel gradation shall be required. 2 graded sand gravel cushion constructio
21、n technology. Graded sand gravel cushion construction can be divided into the rolling way groove, transport, plastic sprinkler paving rolling and early maintenance five step. Graded gravel is a kind of loose material, to prevent damage by vehicle, the supervision engineer shall remind the constructi
22、on units in the construction organization plan, to Demi opening Banfu construction method, to avoid traffic chaos caused by construction of graded sand gravel cushion, so that the surface is loose, smoothness and extension.3 according to the construction method of cement stabilized gravel base. It c
23、an be divided into plant mixing method and mixing method in two forms. Base the road mixing method, on the base by plant mixing method. Cement stabilized gravel as the high-grade highway pavement base in the pavement structure, is an important part of the overall strength of pavement, in relation to
24、 the height and can ensure the normal use in pavement design period.4 cement stabilized gravel base construction technology. Cement stabilized gravel base construction technology two. Road mixing method in the construction of cement stabilized gravel base, process is divided into: the original flat
25、sandy gravel, cement, feeding, watering close placement of paving cement, mechanical mixing, integer leveling, compaction watering. Plant mixing method in the construction of cement stabilized sand gravel, process is divided into preparation, dosage of cement, water mixing, transportation, paving an
26、d rolling on the road and watering etc.5 highway roadbed graded sand gravel cushion. Roadbed review, building engineer in graded sand gravel cushion construction, must have completed the review and acceptance of the subgrade, pavement construction units to organize handover, handover procedures shal
27、l be borne by the resident supervision engineer organization, subgrade, pavement by two construction unit leadership and technical responsible persons attended, roadbed is completed, by the roadbed construction unit the self-check“ roadbed self-inspection report“; materials testing, pavement constru
28、ction unit must submit to the Engineer for the material test of graded sand gravel. Grit particles screening test, average every half a kilometer of supervision engineer in construction period of supervision engineers to review the material, to meet the technical requirements, graded gravel, section
29、s on graded gravel can be used, gravel capacity test, heavy duty standard laboratory. To determine the optimal moisture content and maximum density.In three, the roadbed construction technology measures1 quality control for roadbed. In the highway roadbed structure design of soil base modulus of res
30、ilience of effect of structure layer. On the control of subgrade compaction control and soil, to ensure optimum moisture content, intensity control of subgrade engineering.2 water damage control. Water on the roadbed using properties of the impact is bigger, it reduces the strength of subgrade, espe
31、cially in hot summer weather, the rain infiltration integral ballast bed. Formation of high temperature water, in the traffic loads, gravel peeling off, the separation of the two, formed under the pit road in the stream, surface construction on waterproof layer treatment, so that water does not to s
32、tructure layer, thus avoiding the emergence of such destruction.3 prevention and control of cracks in. Highway usually adopts the integral ballast bed, monolithic track bed crack type basically can be divided into two categories, the crack formed by the reflection crack and surface layer produced by
33、 low temperature shrinkage crack, this is the first kind of non load crack : the other side is the repeated vehicle load and the cracks, it is because the whole bed basic tensile stress exceeds its bending strength and generate a mesh of irregular crack, the design fully consider. The construction o
34、f good quality control is to solve the first crack.Monolithic roadbed cracks control. Selection of small contraction of cement stabilized base construction structure, taking into account the cement stabilized material crack mechanism.Monolithic roadbed surface layer crack prevention. Asphalt monolit
35、hic non load crack of low temperature and fatigue crack. It is mainly related to the quality of bitumen, asphalt temperature sensitivity and penetration, the domestic and foreign many tests show that, needle of index is higher, the lower the temperature sensitivity.Highway subgrade quality for road use performance influence, therefore in the roadbed construction in strict accordance with the standard requirements, according to different roadbed project to take different measures.
