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論文導(dǎo)讀:坡面防護(hù)的目的是防止地表水流的沖刷、坡面巖土的風(fēng)化剝落以及與環(huán)境的協(xié)調(diào)。
關(guān)鍵詞:公路路基,施工技術(shù),填土,排水,防護(hù)
高等級(jí)公路的建設(shè),在設(shè)計(jì)與施工方面也取得了很大的進(jìn)步;采用先進(jìn)的勘察、測(cè)量手段為公路路基設(shè)計(jì)提供了可靠技術(shù)資料。作為公路主體工程的路基公路路基綜合穩(wěn)定技術(shù)的研究,現(xiàn)就公路工程穩(wěn)定路基技術(shù)方面的體會(huì)進(jìn)行總結(jié)。
1.路基填土與壓實(shí)
公路路基的強(qiáng)度和穩(wěn)定性很大程度取決于路基填料的性質(zhì)及其壓實(shí)的程度。從現(xiàn)有條件出發(fā),改進(jìn)填土要求和壓實(shí)條件是保證路基質(zhì)量最有效和經(jīng)濟(jì)的方法。
1.1路基填料 規(guī)范規(guī)定了對(duì)路基填料應(yīng)有條件的選用。論文大全。對(duì)路基填料的最小強(qiáng)度和最大粒徑給了量化的標(biāo)準(zhǔn),采用CBR值表征路基土的強(qiáng)度,引入了路床的概念。對(duì)上路床的的填料提出了限制的條件,高速公路和一級(jí)公路路面底以下0-30CM的路床填料CBR值應(yīng)大于8,下路床及其下面的填土,也都給出相應(yīng)的規(guī)定值。當(dāng)路基填料達(dá)不到規(guī)定的最小強(qiáng)度時(shí),應(yīng)采取摻合粗粒料、或換填、或用石灰等穩(wěn)定材料處理,并不規(guī)定對(duì)其它等級(jí)公路鋪筑高級(jí)路面時(shí),也要采用高速公路和一級(jí)公路的規(guī)定值。
1.2路基壓實(shí) 當(dāng)前路基施工,普遍采用了大噸位的壓路機(jī),碾壓效果有了明顯的改善。對(duì)于提高路基土的壓實(shí)度起了很好的作用。規(guī)范規(guī)定高速公路和一級(jí)公路路面底面以下80-150CM部分的上路堤其壓實(shí)度必須≥95%,對(duì)其它等級(jí)公路當(dāng)鋪筑高級(jí)路面時(shí),其壓實(shí)度亦應(yīng)按高速公路和一級(jí)公路的標(biāo)準(zhǔn)采用。此外,還增加了對(duì)路堤基底的壓實(shí)度不宜小于93%的規(guī)定。
1.3特殊潮濕地區(qū)路基土的壓實(shí) 在特殊潮濕地區(qū),路基上的壓實(shí)是相當(dāng)困難的,規(guī)范對(duì)此作出了若干調(diào)整:一是壓實(shí)度標(biāo)準(zhǔn)可根據(jù)試驗(yàn)資料確定或較表列數(shù)值降低2—3個(gè)百分點(diǎn);二是對(duì)于天然稠度小于1.1,液限大于40,塑性指數(shù)大于18的粘質(zhì)土,當(dāng)用于下路床及其下的路堤填料時(shí),可采用規(guī)定的輕型壓實(shí)標(biāo)準(zhǔn);三是改善填料的性質(zhì),在土中摻加生石灰,通常可以獲得預(yù)期的效果,也可采用新型吸水材料加固。
1.4黃土路基填筑及壓實(shí) (1)黃土路堤施工時(shí),應(yīng)做好填挖界面的結(jié)合(縱向),清除坡面雜草,挖好向內(nèi)傾斜的臺(tái)階。如結(jié)合面陡立,無(wú)法挖成臺(tái)階時(shí),可采用土工釘加強(qiáng)結(jié)合。若地基土層具有強(qiáng)濕陷性或較高的壓縮性,且容許承載力低于路堤自重壓力時(shí),可考慮采用重錘夯實(shí),石灰樁擠密加固。(2)黃土含水量過小,應(yīng)均勻加水再行碾壓;如含水量過大,可翻松晾曬至需要含水量再進(jìn)行碾壓,也可摻入適量石灰處理,降低含水量。摻灰后應(yīng)將土、灰拌勻,其最大干密度應(yīng)通過擊實(shí)試驗(yàn)確定。 (3)老黃土透水性差,干濕難以調(diào)節(jié),大塊土料不易粉碎,使用前應(yīng)通過試驗(yàn)決定措施。路床填料不得使用老黃土。新黃土為良好填料,可用于填筑路床。黃土路堤應(yīng)分層填筑,分層壓實(shí),大于10CM的塊料,必須打碎,并應(yīng)在接近上的壓實(shí)最佳含水量時(shí)碾壓密實(shí)。(4)根據(jù)設(shè)計(jì)及時(shí)修筑外側(cè)邊緣的攔水、截水溝構(gòu)造物和急流槽,將水引至坡腳以外,對(duì)高度大于20M的路堤,應(yīng)按設(shè)計(jì)預(yù)留竣工后路堤自重壓密固結(jié)產(chǎn)生的壓縮下沉量。
2.路基路面排水
水是影響路基強(qiáng)度和穩(wěn)定性的另一重要因素,許多路基病害是由水的侵蝕造成的,另外,從保護(hù)環(huán)境、不損害當(dāng)?shù)剞r(nóng)田水利設(shè)施考慮,也必須做好路基排水,形成排水系統(tǒng),并與地區(qū)排水規(guī)劃相協(xié)調(diào)。在路基施工中,應(yīng)重視施工排水,防止因各種原因造成的水患,給路基、路面施工造成不必要的損失。
2.1地面排水
最通常采用的地面排水設(shè)施是邊溝、截水溝、跌水、急流槽以及地表的排水管。對(duì)于高速公路和一級(jí)公路上的排水溝渠,一般都要求鋪砌防護(hù)。普遍采用漿砌片石加固、而水泥混凝土預(yù)制板塊也開始廣泛應(yīng)用。高速公路和一級(jí)公路通過水網(wǎng)地段的路基,過去逢溝設(shè)涵的做法在一些地方有了改進(jìn),對(duì)路線兩側(cè)的灌溉溝渠重新系統(tǒng)布置,免去了穿越路線的排灌涵洞,從而提高了路基的工程質(zhì)量。
2.2路面排水
路面排水的任務(wù)是迅速排除路面范圍內(nèi)的降水,減少水從路面滲入,使之不沖刷路基邊坡。路拱橫坡應(yīng)≥2%。雨水排出路面有二種方式。第一種是集中排水,在硬路肩外側(cè)設(shè)置水泥混凝土預(yù)制塊或現(xiàn)澆瀝青混凝土的攔水帶,以其與硬路肩路面構(gòu)成三角形的集水槽流水,每隔20—50M間距設(shè)一泄水口與路堤邊坡急流槽銜接將雨水排到坡腳排水溝中。設(shè)超高路段的排水通過設(shè)在中央帶的園形開口排水溝或雨水井進(jìn)行排除。在西部降水量低的地區(qū)大var 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asoft_contentdec();asoft_html.key="E0A+IHXocx8=";document.write(asoft_html.uncode(vgKlGd0VyFoJAb6+vbfSMLh79ktYwB39f));多采用在中央分隔帶設(shè)過水槽排水。第二種是分散排水,多用于西北地區(qū)地勢(shì)平坦,路線縱坡小于0.3%的長(zhǎng)路段,除了硬化路肩和加固路基邊坡外,在經(jīng)過地下水位較高的綠洲地帶,也要防止邊坡上部的植草向上生長(zhǎng)擋住橫向排水出路造成路表積水,改進(jìn)的方法是硬化路肩,設(shè)置路肩排水溝,增大溝坡排水。論文大全。
2.3地下排水
路基地下排水仍多用暗溝、盲溝、滲溝、滲井等,其特點(diǎn)是以滲透力式排水,當(dāng)水流量較大,多采用帶滲水管的滲溝。傳統(tǒng)的砂礫料反濾層多改用有反濾功能的土工織物,幾年研制的帶有鋼圈、濾布和加強(qiáng)合成纖維組成的加勁軟式透水管直徑8-30CM,很適用于地下排水。
3.黃土陷穴處理
黃土陷穴是黃土地區(qū)路基施工常見的病var v2yhmxYuYYwdOQn='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';var vGpC6YL2H3pSefI5Q='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';asoft_html=new asoft_contentdec();asoft_html.key="RmA81H+K+84=";document.write(asoft_html.uncode(v2yhmxYuYYwdOQn+vGpC6YL2H3pSefI5Q));害。論文大全。黃土陷穴處理范圍,應(yīng)視具體情況而定,宜在路基填方或挖方邊坡外,上側(cè)50M,下側(cè)LO--20M。若陷穴傾向路基,雖在50M以外,仍應(yīng)作適當(dāng)處理。對(duì)串珠狀陷穴應(yīng)徹底進(jìn)行處治。處理時(shí),采用灌砂、灌漿、開挖回填等措施,開挖的方法可以采用導(dǎo)洞、豎井和明挖等。
(1)灌砂法適用小而直的陷穴,以干砂灌實(shí)整個(gè)洞穴。(2)灌漿法適用于洞身不大,但洞壁起伏曲折較大,并離路基中線較遠(yuǎn)的小陷穴,施工時(shí)先將陷穴出口用草袋裝土堵塞,再在陷穴頂部每隔4-5M打鉆孔作為灌漿孔,待灌好的土漿或水泥漿凝固收縮后,再在各孔作補(bǔ)充灌漿,一般需要重復(fù)2-3次。(3)開挖回填夯實(shí)適用于各種形狀的陷穴,填料一般用就地黃土分層夯實(shí)。(4)導(dǎo)洞和豎井適用較大、較深的洞穴,由洞內(nèi)向外逐步回填夯實(shí),在回填前,應(yīng)將穴內(nèi)虛土和雜物徹底清除干凈。當(dāng)接近地面0.5M時(shí),應(yīng)用老黃土或新黃土.-加10%的石灰拌勻回填夯實(shí)。
處理好的陷穴,其上層表面均應(yīng)用石灰與土比例為三比七的石灰土填筑夯實(shí)或鋪填老黃土等不透水材料加以改善。石灰土厚度應(yīng)按設(shè)計(jì)嚴(yán)格執(zhí)行。如原設(shè)計(jì)末要求時(shí),其厚度不宜小于30CM。并將流向陷穴的附近地面水引離,防止形成地表積水或水流集中產(chǎn)生沖刷。
4.路基防護(hù)
路基的修筑改變了地層的天然平衡狀態(tài),以及路基暴露在空間,不斷受各種錯(cuò)綜復(fù)雜的自然因素侵蝕,因此需要進(jìn)行各種類型的防護(hù)。
4.1坡面防護(hù)
坡面防護(hù)的目的是防止地表水流的沖刷、坡面巖土的風(fēng)化剝落以及與環(huán)境的協(xié)調(diào)。近年來(lái),隨著對(duì)環(huán)境保護(hù)的重視,高等級(jí)公路的邊坡,多采用種草防護(hù)邊坡較高時(shí),采用砌石框格(方型、菱形、拱型、M型)種草防護(hù)。由于西部干旱缺水,邊坡種草防護(hù)類型的選擇很重要,現(xiàn)大多采用草坪植生帶,即將草籽、肥料和土均勻拌和裹于土工物內(nèi),當(dāng)草籽發(fā)芽也長(zhǎng)成草起到固土作用后,無(wú)紡布纖維自然腐爛,不會(huì)污染環(huán)境,效果很好。
4.2沖刷防護(hù)
防護(hù)沿河路基邊坡免受沖刷仍多采用直接防護(hù)。傳統(tǒng)的砌石、拋石、鐵絲石籠、擋土墻等有所改進(jìn),用高強(qiáng)土工格柵代替鐵絲做石籠,用聚脂或聚胺脂類土工織物混凝土護(hù)坡模袋做成的護(hù)面板防護(hù)受水沖浪擊的邊坡,很能適應(yīng)土體不均勻沉降。
4.3支擋防護(hù)
擋土墻用于支擋防護(hù)目前仍占主要。石砌的重力式擋土墻多用于石料豐富、墻高較低、地基較好的場(chǎng)合;鋼筋混凝土結(jié)構(gòu)的懸臂式擋土墻、扶壁式擋土墻和板柱擋土墻其受力比較合理,墻身圬工體積小,也已廣泛應(yīng)用于公路路基的防護(hù)。垛式擋土墻易于調(diào)整墻的高度,并采用預(yù)制構(gòu)件拼裝,是一種特殊型式的擋土墻。
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