趙德才 許列 夏云東
摘要:夾巖水利樞紐工程兩路口隧洞進(jìn)口開挖后其右側(cè)邊坡存在滑坡、崩塌等地質(zhì)災(zāi)害風(fēng)險(xiǎn),為應(yīng)對(duì)可能發(fā)生的地質(zhì)災(zāi)害,采取了邊坡加固處理措施,并驗(yàn)證了其處理效果。施工過程中布置相應(yīng)監(jiān)測(cè)儀器進(jìn)行持續(xù)觀測(cè),基于監(jiān)測(cè)數(shù)據(jù)的統(tǒng)計(jì)和分析,對(duì)邊坡加固處理后的穩(wěn)定性進(jìn)行了分析評(píng)價(jià)。分析結(jié)果表明:邊坡抗滑樁能夠承受來自邊坡淺覆蓋層的側(cè)方擠壓力并保持相對(duì)穩(wěn)定狀態(tài),邊坡加固處理效果較好。對(duì)于類似的淺覆蓋層為殘坡積黏土夾碎石及崩塌堆積物的邊坡,采用聯(lián)排抗滑樁的加固處理方法,可有效治理邊坡的淺層大范圍滑動(dòng),且施工難度相對(duì)較低,是一種經(jīng)濟(jì)、合理、有效的處理措施。
關(guān)鍵詞: 邊坡加固;應(yīng)力監(jiān)測(cè);邊坡穩(wěn)定性;夾巖水利樞紐工程;貴州省
中圖法分類號(hào):TV223文獻(xiàn)標(biāo)志碼:ADOI:10.15974/j.cnki.slsdkb.2020.09.003
Abstract: After the excavation of Lianglukou tunnel entrance of the Jiayan Hydro-complex Project, its right-side slope bears the risks of geological hazards such as landslide and collapse, to cope with the possible geological disaster, reinforcement measures were taken to mitigate the risks. To verify the effectiveness of the measures, monitoring devices were installed in the construction for continuous monitoring and the stability of the reinforced slope was then analyzed and assessed using the monitoring data and statistical analysis method. The results showed that the reinforcement measures were effective, anti-slide pile was able to withstand the lateral extrusion pressure from the shallow overburden of the slope and still remained relatively stable. For the similar clay shallow overburden slopes mixed with gravels and deposits, large range sliding of the shallow layer can be effectively controlled by installing rows of anti-slide piles. The measure is proved to be economical and feasible.
Key words: slope reinforcement; stress monitoring; slope stability; Jiayan Hydro-complex Project; Guizhou Province
地質(zhì)環(huán)境是人類生活的載體,但我國(guó)地質(zhì)環(huán)境狀況不容樂觀,各類地質(zhì)災(zāi)害頻發(fā)。根據(jù)國(guó)家統(tǒng)計(jì)局?jǐn)?shù)據(jù),21世紀(jì)初我國(guó)因地質(zhì)災(zāi)害所帶來的損失較大,僅2000年因地質(zhì)災(zāi)害傷亡人數(shù)就高達(dá)27 697人;經(jīng)過重點(diǎn)防治后,在2013年,由滑坡、崩塌、泥石流以及地面塌陷帶來的直接經(jīng)濟(jì)損失依然高達(dá)104億元;2013~2017年地質(zhì)災(zāi)害累計(jì)經(jīng)濟(jì)損失255億元,5 a累計(jì)傷亡 3 104人,傷亡人數(shù)僅次于地震與洪水災(zāi)害。地質(zhì)災(zāi)害對(duì)環(huán)境破壞及其次災(zāi)害所造成的損失更是無法計(jì)量[1]。在工程建設(shè)過程中邊坡的安全性至關(guān)重要,針對(duì)邊坡穩(wěn)定性開展研究具有重要的實(shí)際意義。
本文以夾巖水利樞紐工程(以下簡(jiǎn)稱“夾巖工程”)北干渠5標(biāo)段兩路口隧洞進(jìn)口右側(cè)邊坡為例,通過初期臨時(shí)監(jiān)測(cè)及現(xiàn)場(chǎng)巡視檢查掌握了邊坡表面變形情況,根據(jù)初期監(jiān)測(cè)數(shù)據(jù)制定了邊坡加固處理措施,同時(shí)在加固處理實(shí)施過程中布置相應(yīng)監(jiān)測(cè)儀器并持續(xù)觀測(cè),以此掌握邊坡加固處理后的穩(wěn)定情況,同時(shí)驗(yàn)證該加固處理措施是否合理有效。
1 工程概況
兩路口隧洞進(jìn)口右側(cè)邊坡為河谷岸坡、斜坡地形,地形坡度10°~20°。地表覆蓋層為殘坡積黏土夾碎石及崩塌堆積物,厚0.6~17.6 m,下伏基巖為T2g1薄至中厚層泥質(zhì)白云巖、白云巖、泥巖。巖體強(qiáng)風(fēng)化層厚度8~12 m,弱風(fēng)化層厚度10~15 m。巖層產(chǎn)狀為353°∠12°。地下水類型為基巖裂隙水,埋藏淺,隧洞進(jìn)口段位于地下水位變動(dòng)帶。
工程初期在兩路口隧洞進(jìn)口右側(cè)邊坡陸續(xù)開挖修建了施工便道、施工營(yíng)地、拌和站、砂石料堆放場(chǎng)等。進(jìn)入雨季之后工程區(qū)域遭遇連續(xù)強(qiáng)降雨,隧洞進(jìn)口右側(cè)邊坡中、上部產(chǎn)生大量地表裂縫,部分裂縫開合度達(dá)到50 cm以上,裂縫延伸較廣,有明顯滑移趨勢(shì),根據(jù)當(dāng)時(shí)臨時(shí)表面變形觀測(cè)數(shù)據(jù),該邊坡局部區(qū)域合位移量達(dá)到2 m以上。為應(yīng)對(duì)可能發(fā)生的地質(zhì)災(zāi)害風(fēng)險(xiǎn),決定在該邊坡施工便道以上布置一排抗滑樁進(jìn)行加固處理,邊坡二次加固工程共設(shè)置33根抗滑樁,直徑為1 200 mm,長(zhǎng)度10~15 m,樁身混凝土設(shè)計(jì)強(qiáng)度為C30;施工過程中同時(shí)布置相應(yīng)監(jiān)測(cè)儀器,選取部分抗滑樁在其不同深度段布置鋼筋計(jì),以掌握抗滑樁不同深度受力情況,在其樁頂布置變形觀測(cè)墩以獲得抗滑樁位移情況,在邊坡中部(抗滑樁以上)布置深部位移觀測(cè)孔,孔口布置變形觀測(cè)墩以掌握邊坡不同深度滑移情況。