互通式立交与隧道之间采用小间距方案的研究

Research on the Scheme of Small Spacing between Interchange and Tunnel

为缓解我国山区高速公路互通式立交与隧道间距无法满足设计规范和设计细则的矛盾,灵活处理互通式立交与隧道间距的问题,提高该段落范围内的运营安全性,研究了山区高速公路互通式立交选址困难的普遍性问题。在具体勘设过程中设计人员由于对规范的理解和掌握尺度不同,普遍存在以下问题:为了满足规范要求而造成互通式立交工程规模和工程造价显著增加;互通式立交移位设置导致服务对象上下高速公路绕行距离较远,运营成本和社会成本显著提高;互通式立交与隧道段交通事故高发等。具体工程实例表明,在地形、地质、地物等因素限制较多的特殊情况下,根据互通式立交功能和服务对象等实际情况,通过加强交安设施设计来保障运营安全,由此突破互通式立交与隧道的距离要求,属于不得已而为之,但互通式立交方案也是可行的。建议对路线规范相应条款适当放松,改“应”为“宜”,给设计人员留下灵活设置的余地。研究成果对于合理降低工程规模和造价,提高公路安全运营水平,具有一定的经济价值及社会意义。

In order to alleviate the contradiction of small spacing between interchange and tunnel of mountain highways in China, eliminate the concerns and misunderstandings of designers, deal with the problem of interchange and tunnel spacing flexibly and improve the operation safety on such sections, the difficulty of determining the location of interchange in mountain highways is studied in the paper, and the problems in the process of survey and design due to designer’s different understanding and knowledge of specifications are concluded. The following problems are common: in order to meet the requirements of the specifications, the scale and cost of the interchange project have increased significantly;the shifting setting of the interchange has led to a long detour distance for the service object on and off the expressway, and the operating cost and social cost have increased significantly;traffic accidents frequently occur on the interchange and the tunnel section, etc.. Combined with specific example, it is shown that under the special circumstances of terrain, geology, ground objects and other factors, according to the actual situation of interchange function and service object, it is necessary to strengthen the design of interchange facilities to ensure operation safety and break through the distance requirement between interchange and tunnel. It is suggested that the wording of corresponding provisions in the Design Specification for Highway Alignment should change from "should" to "suggest", leaving room for designers to set up flexibly. This scheme has great economic value and social significance for reasonably reducing the project scale and cost and improving the level of highway safety operation.