博士眼里25萬噸重的“孩子”

李野 張軍興

李亞勇最近做了好幾個相同的夢——在剛通車的禮嘉大橋上，他抱著7個月大的孩子在橋上拍照。

今年30歲的李亞勇，從2011年到重慶大學攻讀碩士、博士，2016年進入中建隧道工作，就一直沒離開重慶。2017年開始，李亞勇在二橫線指揮部任項目副總工，作為重慶二橫線快速路重點工程的禮嘉嘉陵江大橋，就是他負責的項目之一。在他眼中，這座25萬噸重的大橋從無到有，不僅是技術(shù)與美學的完美結(jié)合，更像是他創(chuàng)造的有生命的孩子。

這是一座上承式梁拱組合預應力混凝土剛構(gòu)橋，屬于全新的設計方案，在全國也是首例。它是在常規(guī)連續(xù)剛構(gòu)橋、空腹式連續(xù)剛構(gòu)橋形式上的新改型，建造階段集梁橋、懸澆拱橋、矮塔斜拉橋施工工藝于一身，需經(jīng)歷臨時扣索安拆、上下弦箱梁交匯、主橋合龍等多次體系轉(zhuǎn)換，沒有成功的經(jīng)驗可以借鑒。

面對種種困難與挑戰(zhàn)，李亞勇帶領項目團隊攻克了一個又一個難關。尤其是BIM技術(shù)的嫻熟運用，更是助力二橫線項目獲得了全球含金量最高的BIM大獎——2020年AEC全球卓越工程BIM大賽最佳實踐獎第一名。

所謂“BIM技術(shù)”，通俗來說，就是把二維圖紙以三維建筑模型展現(xiàn)，通過建筑模型前置開展整座大橋的全方位模擬，如建造工序、施工進度的模擬等。

“上弦箱梁與下弦拱梁交匯合龍階段，我們運用BIM技術(shù)對上下弦梁合龍施工工藝進行反復推演，發(fā)現(xiàn)了圖紙的錯漏與偏差，并提出最佳合龍方案，有效節(jié)約了工期與成本。”李亞勇說，“既然是我?guī)У摹⒆印揖偷米屗聣殉砷L。”

作為橋都，重慶已有很多優(yōu)秀的橋梁建筑，比如朝天門大橋、東水門大橋等等。李亞勇希望禮嘉大橋以后也能成為人們口中“別人家的孩子”，談起它時都能豎起大拇指，而且它的創(chuàng)新技術(shù)與專利也能為別人提供借鑒。李亞勇說，等它完全“長大了”，要讓它捧回“魯班獎”“詹天佑獎”，那時候他會帶著全家人一步一步地走完整座大橋。

Li Yayong had the same dream several times recently--on the newly opened Lijia Bridge， he took pictures with his 7-month-old child on the bridge.

Li Yayong， 30 years old， went to Chongqing to pursue his master’s and doctor’s degrees at Chongqing University in 2011， and entered China Construction Tunnel in 2016. Since then， he has never left Chongqing. Since 2017， Li Yayong has served as deputy chief engineer for projects in the headquarters of Erhengxian. As the key project of Chongqing Erhengxian Expressway， Lijia Jialing River Bridge is one of the projects he charged. In his eyes， the 250，000-ton bridge built from scratch is not only a perfect combination of technology and arts， but also a living child he created.

This is a deck beam-arch composite prestressed concrete rigid frame bridge， which adopts a brand-new design scheme， the first in China. It is a new modification of conventional continuous rigid frame bridge and open-web continuous rigid frame bridge. In the construction stage， it integrates the construction technology of beam bridge， suspended arch bridge and low-pylon cable-stayed bridge. It needs to undergo many system transformations such as temporary cable installation and dismantling， intersection of upper and lower chord box girders， closure of the main bridge， etc. There is no successful experience to learn from.

Facing all kinds of difficulties and challenges， Li Yayong led the project team to overcome one difficulty after another. In particular， the skillful application of BIM technology helped the Erhengxian Project win the BIM award with the highest gold content in the world-the first best practice award in the 2020 AEC Global Excellence Project BIM Competition.

The so-called "BIM technology"， generally speaking， is to show two-dimensional drawings as three-dimensional building models， and to carry out all-round simulation of the whole bridge through the front of the building models， such as the simulation of construction procedures and construction progress.

"In the closing stage of the intersection of the upper chord box girder and the lower chord arch girder， we used BIM technology to repeatedly deduce the closing construction technology of the upper and lower chord beams， found the mistakes and deviations of the drawings， and proposed the best closing scheme， effectively saving the construction period and cost." Li Yayong said， "Since I brought the ’child’ to the world， I have to raise him up."

As a capital of bridges， Chongqing is home to many excellent bridge buildings， such as the Chaotianmen Bridge， Dongshuimen Bridge， and so on. Li Yayong hopes that Lijia Bridge will become what people call "other people’s children" in the future. When talking about it， they can give a thumbsup. Its innovative technology and patents can also provide references for others. Li Yayong said that when it is a "grownup" in real terms， he wants it to bring home the "Luban Award" and "Zhan Tianyou Award". At that time， he will take his whole family to walk the whole bridge step by step.