馬雪城 李國(guó)芬 趙康
摘 要:為得到荷位、軸載、大氣溫度以及計(jì)算方法各因素對(duì)鋼橋面鋪裝車轍的影響,本文以上層高彈改性瀝青混合料(35 mm)+下層澆筑式瀝青混合料(40 mm)復(fù)合鋪裝結(jié)構(gòu)為研究對(duì)象,并建立鋼橋面鋪裝模型,通過(guò)單軸貫入試驗(yàn)獲取材料的蠕變參數(shù),利用ABAQUS計(jì)算鋼橋面鋪裝車轍。分析表明:車轍主要發(fā)生在下層的澆筑式瀝青混合料;橫向荷位變化對(duì)車轍的影響遠(yuǎn)大于縱向荷位;車轍值總體與溫度呈正相關(guān)性,與季節(jié)的溫度變化相一致;連續(xù)變溫下鋪裝車轍的計(jì)算方法比恒溫下的要準(zhǔn)確,車轍深度隨著接地壓力的增加而不斷增大。研究結(jié)論對(duì)鋼橋面鋪裝設(shè)計(jì)和車轍預(yù)估有一定的意義。
關(guān)鍵詞:車轍;蠕變?cè)囼?yàn);鋼橋面鋪裝;有限元
中圖分類號(hào):U443.33 文獻(xiàn)標(biāo)識(shí)碼:A 文章編號(hào):1006-8023(2018)05-0077-06
Abstract: In order to get the influence of load location, axle load, atmospheric temperature and calculation method on rutting of steel bridge deck pavement. The composite pavement structure of high elastic modified asphalt mixture (35mm) and under layer pouring asphalt mixture (40mm) as research object in this paper, and a steel bridge deck pavement model was established, through a single axis penetration test to obtain the material creep Variable parameters, using ABAQUS to calculate the steel deck pavement. The analysis shows that rutting mainly occurs in the under layer of asphalt mixture; the effect of lateral load change on the rutting is much greater than that of the longitudinal load; the rutting value is positively correlated with temperature, which is consistent with seasonal temperature change; the calculation method of the pavement at the continuous temperature change is more accurate than at the constant temperature, and the depth of the rut increases with the increase of the ground pressure. The research conclusion is of significance for the design and rutting prediction of steel bridge deck pavement.
Keywords: Rutting; creep test; steel bridge deck pavement; finite element
0 引言
目前我國(guó)多數(shù)大跨徑鋼橋面鋪裝出現(xiàn)了不同程度的破壞,其中車轍病害日益嚴(yán)重,大大降低了鋼橋面鋪裝的使用性能[1-2],因而需要對(duì)車轍進(jìn)行深入研究分析。課題組對(duì)比分析了基于澆筑式瀝青混合料的復(fù)合鋪裝結(jié)構(gòu)高溫性能[3],并基于修正Burgers模型進(jìn)行了車轍預(yù)估分析[4-6]。湯文[7]采用多參數(shù)得到車轍預(yù)估模型,楊軍、錢振東[8-10]等采用Bailey-Norton模型,龍堯[11]采用Burgers模型,Al-Qadi I L[12]采用廣義的Maxwell模型對(duì)混凝土材料參數(shù)進(jìn)行獲取并進(jìn)行車轍預(yù)估,但是未對(duì)連續(xù)變溫下的鋪裝進(jìn)行準(zhǔn)確考慮,本文以南京長(zhǎng)江四橋的鋪裝為分析對(duì)象,通過(guò)ABAQUS建立局部箱梁模型,通過(guò)不同的荷位、溫度等因素對(duì)車轍的影響分析。
1 鋼橋面鋪裝分析模型
1.1 有限元模型參數(shù)
本文采取的計(jì)算模型具體參數(shù)參照南京長(zhǎng)江四橋,見(jiàn)表1。鋪裝為兩層結(jié)構(gòu),上層高彈改性瀝青混合料(35 mm)+下層澆筑式瀝青混合料(40 mm),有限元模型如圖1所示。
1.2 材料參數(shù)
混合料的蠕變模型采用Bailey-Norton[13-14]模型,其表達(dá)式為:
式中:為應(yīng)變速率;σ為應(yīng)力;t 為荷載累計(jì)作用時(shí)間;A、m、n為系數(shù),主要與溫度和應(yīng)力大小有關(guān)。
為了使獲得的參數(shù)更接近鋼橋面鋪裝的真實(shí)受力狀態(tài),實(shí)驗(yàn)制作300 mm×300 mm×50 mm的標(biāo)準(zhǔn)車轍板試件,分別為高彈改性瀝青混合料試件和澆筑式瀝青混合料試件,共有4種溫度水平,分別為30、40、50、60℃,每種溫度水平共用3組試件,對(duì)混合料的蠕變參數(shù)分別擬合,擬合結(jié)果見(jiàn)表2。
1.3 荷載參數(shù)
根據(jù)李凌林[15-18]等研究,輪胎接地壓力與輪胎的內(nèi)壓處于不平衡的關(guān)系,參照經(jīng)驗(yàn)公式計(jì)算不同軸載作用下的接地壓力,公式如下:
p=0.290×pt+0.0042×P+0.1448。 (2)
式中:p為輪胎接地壓力,MPa;Pt為輪胎充氣壓力,MPa;P為軸載,kN。
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