设计总说明：本设计根据给定资料，通过对原始数据的分析，根据该路段的性质、地形、地物、水文等自然条件，依据《公路工程技术标准》(JTGB01—2014)等交通部颁发的有关技术指标，完成了以下内容：根据给定起终点，选择合适控制点，根据等高线间距和选定的平均纵坡，初步拟定可行的路线方案。设计时，通过选择三条可行的路线，经过方案比选后，从而确定出一条最合适的路线。

此路线桐千线：总长为2764.976m，属于二级公路，速度为60km/h，车道数为两车道，路面宽为7m，两侧路肩宽都为1.5m。经修正确定出满足要求的平面线形,并做详细的线型设计，特殊线型设计，在平曲线中有4个转角，圆曲线半径依次为250m,250m,300m,300m，缓和曲线长依次为70m,70m,75m,70m。同向曲线间的最小直线长度满足大于3V（即180m）的要求，反向曲线间的最小直线长度满足大于2V（即120m）的要求。根据《公路路线设计规范》(JTGD20—2017)交通部规定最大纵坡、限制坡长、

纵坡折减等，结合控制点和经济点高程，确定路线纵断面设计线，竖曲线设计阶段：竖曲线中有4个变坡点，竖曲线半径依次为3650m,8426m,2500m,3000m。当变坡点在平曲线中的曲线段时满足“平包竖”原则，经过拉坡设计后整条路线的填挖方也基本平衡。根据填挖高度设计路基、挡墙等，完成横断面设计。土石方调配时，通过计算借方，弃方和总运量来解决设计道路的土石方数量的平衡与利用。路基设计过程通过圆弧法来计算土体稳定性。在桩号K0+500-K0+560处通过设置20m长的8m挖方仰斜式挡土墙和40m长的9m挖方仰斜式挡土墙来保证道路边坡土体的稳定性，修筑挡土墙是为了阻止土体坍滑，它主要应用于路堤，路堑边坡、隧道洞口、桥梁两端的支撑。根据公路等级和交通量，确定路面等级并完成路面结构设计，包括沥青路面结构设计及水泥路面结构设计；根据行车、行人及排水的要求，确定通道、涵洞及桥梁位置并布置。通道及涵洞设计：在桩号K0+120处设置2.5m高的通道，供行车及行人用；在桩号K1+680处设置3m高的通道，供行车及行人用；在桩号K1+940处设置2m高的涵洞，供行人及排水用。桥梁：在桩号K1+320-K1+440处设置预应力混凝土简支T形梁桥：25+2*35+25，跨径为120m,分4跨。在桩号K1+640-K1+680处设置预应力混凝土简支T形梁桥：20+20，跨径为40m,分2跨。最后进行项目概预算。

关键词：平、纵、横线形设计，路面结构设计，挡土墙设计，桥涵设计，概预算。

Second level road design of tongqian line 

Design general description: this design according to the given data, through the analysis of original data, according to the nature of the sections, terrain, terrain, hydrology and other natural conditions, according to "highway engineering technical standards" (JTG B01-2014) issued by the relevant technical indexes such as the ministry of communications, completed the following content: according to a given destination, choose appropriate control points, according to the average longitudinal slope, and the spacing between the contour lines of the selected preliminarily formulate feasible route scheme. In the design, three feasible routes are selected, and the most suitable route is determined after the scheme is compared and selected. 

This route has a total length of 2764.976m. It is a second-class highway with a speed of 60km/h. The number of lanes is two lanes, the road width is 7m, and the shoulder width of both sides is 1.5m. Amended, determine the meet the requirements of horizontal alignment, and make a detailed linear design, special lines design, four corner in plane curve, circular curve radius, in turn, is 250 m, 250 m, 300 m, 300 m, easement curve length of 70 m, 70 m, 75 m, 70 m. The minimum line length between the homologous curves satisfies the requirement of greater than 3V (180m), and the minimum line length between the reverse curves satisfies the requirement of greater than 2V (120m). According to specification for design of highway route (JTG D20-2017), the ministry of communications restrictions placed upon the maximum longitudinal slope, slope length, longitudinal slope reduction and so on, combined with control points and economic point elevation, determine the route line profile design, vertical curve design phase: has four variable slope point in vertical curve, vertical curve radius, in turn, is 3650 m, 8426 m, 2500 m, 3000 m. When the changing point of slope is in the curve section of the flat curve, the principle of "flat ladle vertical" is satisfied. Design the roadbed and retaining wall according to the filling height and complete the cross-section design. In the allocation of earthwork, the balance and utilization of earthwork quantity of design road can be solved by calculating the amount of debit, discard and total traffic volume. The stability of soil is calculated by arc method in the course of roadbed design. Around the pile K0 + 500 - K0 + 560 by setting the excavation back 20 m long, 8 m and 40 m long and 9 m oblique earth-retaining wall excavation back inclined type retaining wall to ensure the stability of the slope soil roads, build soil retaining wall is to prevent the collapse sliding, it is mainly used in embankment, cut slope, tunnel portal, Bridges on both ends of the support. According to the highway grade and traffic volume, determine the road grade and complete the road structure design, including asphalt pavement structure design and cement pavement structure design. Determine the location and layout of the passageway, culvert and bridge according to the requirements of driving, pedestrian and drainage. Passageway and culvert design: 2.5m high passageway is set at pile number K0+120 for driving and pedestrian; 3m high passageway at pile number K1+680 for driving and pedestrian; A 2m high culvert for pedestrian and drainage is provided at the location of pile number K1+940. Bridge: prestressed concrete t-beam bridge with simple support is set at pile number K1+ 320-k1 +440:25+2*35+25, span diameter is 120m, pided into 4 spans. The t-beam bridge with simple support of prestressed concrete is set at pile number K1+ 640-k1 +680:20+20, with a span of 40m and 2 spans. Finally, the project budget is estimated.  二级公路桐千线公路设计:http://www.chuibin.com/gongcheng/lunwen_205343.html