張浩
摘要:玉磨鐵路曼勒一號(hào)隧道下穿小磨高速公路勐遠(yuǎn)特大橋,由于高速公路已開通運(yùn)營,隧道開挖施工過程中可能引起橋梁結(jié)構(gòu)地基應(yīng)力發(fā)生變化,產(chǎn)生位移,發(fā)生沉降,導(dǎo)致梁體混凝土局部應(yīng)力過大,產(chǎn)生損傷;同時(shí)預(yù)防橋梁所在山體本身存在不穩(wěn)定因素。因此必須在隧道施工期內(nèi)對(duì)隧道洞內(nèi)、洞頂?shù)乇?、橋墩、隧道及橋墩所在山體進(jìn)行監(jiān)控量測并形成監(jiān)控量測體系,通過監(jiān)測數(shù)據(jù)指導(dǎo)隧道施工,控制形變過大,防止隧道施工對(duì)高速公路造成破壞,確保高速公路橋梁安全穩(wěn)定。通過監(jiān)測了解該工程條件下所表現(xiàn)、反映出來的一些變形規(guī)律和特點(diǎn),為今后類似工程的施工提供借鑒、依據(jù)和指導(dǎo)作用。
Abstract: The Manle No.1 Tunnel of Yumo Railway passes through the Mengyuan bridge of Xiaomo Expressway. Since the expressway has been opened to traffic, the foundation stress of the bridge structure may change during the tunnel excavation process, resulting in displacement and settlement, resulting in too large local stress of the beam body concrete, causing damage; at the same time, there is instability in the mountain where the bridge is located. Therefore, during the tunnel construction period, it is necessary to monitor and measure the tunnel body, the pier top, the pier, the tunnel and the mountain where the pier is located, and form a monitoring and measurement system. The monitoring data guides the tunnel construction, to control deformation to prevent the highway from damage caused by tunnel construction, to ensured that the highway bridge is safe and stable. By monitoring and understanding some deformation laws and characteristics reflected under the engineering conditions, it will provide reference, basis and guidance for the construction of similar projects in the future.
關(guān)鍵詞:監(jiān)測體系;隧道;下穿;橋梁;應(yīng)用
Key words: monitoring system;tunnel undercrossing;bridge application
中圖分類號(hào):U456.3 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 文獻(xiàn)標(biāo)識(shí)碼:A ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?文章編號(hào):1006-4311(2019)15-0125-05
1 ?工程概況
①玉磨鐵路曼勒一號(hào)隧道位于云南省西雙版納傣族自治州勐臘縣境內(nèi),隧道全長8280m,其進(jìn)口工區(qū)長493m,采用雙向掘進(jìn),隧道斜交37°近距離下穿已運(yùn)營通車的小磨高速公路勐遠(yuǎn)特大橋第26跨(見圖1)。
②玉磨鐵路與小磨高速在2015年7月同時(shí)勘察期間,確定的鐵路在高速公路交叉范圍為DK445+970~DK446+110段140m(見圖2)。
③玉磨鐵路曼勒一號(hào)隧道(簡稱“隧道”)與小磨高速公路勐遠(yuǎn)特大橋(簡稱“橋梁”)交叉形式為新通車橋梁上跨在建隧道,隧道從橋梁25、26號(hào)橋墩中間通過,隧道開挖輪廓距25#-0樁基邊緣凈距4.71m、鐵路軌面距樁底
-1.26m(見圖3),距26#-1樁基邊緣凈距4.56m、鐵路軌面距樁底-7.019m。
2 ?隧道地質(zhì)概況
①全隧洞身圍巖為侏羅系中統(tǒng)小紅橋組(J2x)泥巖、砂巖夾礫巖,三疊系中統(tǒng)易比組(T2y)泥巖夾石英砂巖、板巖,二疊系中統(tǒng)長興組上段(P2cb)砂巖夾泥巖、頁巖、灰?guī)r,下段(P2ca)灰?guī)r,二疊系中統(tǒng)龍?zhí)督M(P2l)粉砂質(zhì)泥巖夾砂巖、灰?guī)r、煤層。單斜構(gòu)造區(qū)域。不良地質(zhì)為巖溶、有害氣體、順層偏壓,特殊巖土為膨脹土。
②DK445+970~DK446+110段140m地質(zhì)情況。地表為<2-2>人工填土(Q4ml),厚1~6m,坡殘積粉質(zhì)黏土<7-3>,厚0~4m。其下為二疊系中統(tǒng)龍?zhí)督M(P2l)粉砂質(zhì)泥巖夾砂巖含炭質(zhì)巖、煤層。黃灰、灰黑、淺灰、黃綠色,泥、鈣質(zhì)粉粒結(jié)構(gòu),薄層葉片狀,變質(zhì)作用明顯,質(zhì)軟,具遇水軟化崩解特性。全風(fēng)化帶(W4)厚1~4m,局部厚達(dá)9m;強(qiáng)風(fēng)化帶(W3)厚14~20m,其下為弱風(fēng)化帶(W2)。