當管(guan)(guan)(guan)底為巖石、碎石或多(duo)石地(di)(di)基(ji)(ji)時，對(dui)金屬管(guan)(guan)(guan)道(dao)(dao)(dao)應(ying)鋪(pu)(pu)(pu)墊(dian)(dian)不(bu)小(xiao)于(yu)100 mm厚的(de)中砂(sha)或粗(cu)砂(sha)，對(dui)非金屬管(guan)(guan)(guan)道(dao)(dao)(dao)應(ying)鋪(pu)(pu)(pu)墊(dian)(dian)不(bu)小(xiao)于(yu)150 mm厚的(de)中砂(sha)或粗(cu)砂(sha)，構成(cheng)砂(sha)基(ji)(ji)礎，再在上面鋪(pu)(pu)(pu)設(she)管(guan)(guan)(guan)道(dao)(dao)(dao)，如圖1.3.9(b)所示。當管(guan)(guan)(guan)底地(di)(di)基(ji)(ji)土(tu)質(zhi)松軟，承載(zai)力低或鋪(pu)(pu)(pu)設(she)大管(guan)(guan)(guan)徑的(de)鋼筋混(hun)(hun)凝(ning)土(tu)管(guan)(guan)(guan)道(dao)(dao)(dao)時，應(ying)采(cai)(cai)用(yong)(yong)(yong)混(hun)(hun)凝(ning)土(tu)基(ji)(ji)礎。根據地(di)(di)基(ji)(ji)承載(zai)力的(de)實(shi)際(ji)情況，可采(cai)(cai)用(yong)(yong)(yong)強(qiang)度等級不(bu)低于(yu)C10的(de)混(hun)(hun)凝(ning)土(tu)帶(dai)形基(ji)(ji)礎,也可采(cai)(cai)用(yong)(yong)(yong)混(hun)(hun)凝(ning)土(tu)枕基(ji)(ji)，如圖1.3.9 (c)所示。混(hun)(hun)凝(ning)土(tu)帶(dai)形基(ji)(ji)礎是(shi)(shi)沿管(guan)(guan)(guan)道(dao)(dao)(dao)全長做(zuo)成(cheng)的(de)基(ji)(ji)礎，而混(hun)(hun)凝(ning)土(tu)枕基(ji)(ji)是(shi)(shi)只在管(guan)(guan)(guan)道(dao)(dao)(dao)接口處用(yong)(yong)(yong)混(hun)(hun)凝(ning)土(tu)塊(kuai)墊(dian)(dian)起，其他地(di)(di)方用(yong)(yong)(yong)中砂(sha)或粗(cu)砂(sha)填實(shi)。對(dui)混(hun)(hun)凝(ning)土(tu)基(ji)(ji)礎，如管(guan)(guan)(guan)道(dao)(dao)(dao)采(cai)(cai)用(yong)(yong)(yong)柔性接口，應(ying)每(mei)隔一定(ding)距離在柔性接口下，留(liu)出600~800mm的(de)范圍不(bu)澆筑混(hun)(hun)凝(ning)土(tu)，而

PP波(bo)(bo)(bo)紋(wen)管(guan) 象研究梁的(de)(de)變形一樣,我(wo)們從(cong)純彎(wan)(wan)曲的(de)(de)情況著手,假設彎(wan)(wan)曲狀(zhuang)態下(xia)(xia)的(de)(de)金(jin)屬波(bo)(bo)(bo)紋(wen)管(guan)的(de)(de)軸向(xiang)剖面上取半(ban)(ban)個波(bo)(bo)(bo)峰(feng)(feng)寬度和(he)半(ban)(ban)個波(bo)(bo)(bo)谷(gu)寬度作(zuo)為微量(liang),從(cong)其通徑和(he)波(bo)(bo)(bo)紋(wen)幾何形狀(zhuang)上去分析(見圖(tu)4-1)。常(chang)態下(xia)(xia)的(de)(de)全屬波(bo)(bo)(bo)紋(wen)管(guan),AA、BB′、CC'、DD都(dou)是(shi)互相平行的(de)(de)。PE波(bo)(bo)(bo)紋(wen)管(guan)彎(wan)(wan)曲之后,軸心線(xian)EG變成(cheng)了撓曲線(xian)。由(you)于(yu)撓曲線(xian)上方(fang)的(de)(de)波(bo)(bo)(bo)谷(gu)的(de)(de)半(ban)(ban)圓(yuan)弧所(suo)受拉應(ying)(ying)力(li)與(yu)(yu)其下(xia)(xia)方(fang)波(bo)(bo)(bo)谷(gu)的(de)(de)半(ban)(ban)圓(yuan)弧所(suo)受壓應(ying)(ying)力(li)相等(deng),所(suo)以,BB依然平行于(yu)AA;由(you)于(yu)撓曲線(xian)上方(fang)的(de)(de)波(bo)(bo)(bo)峰(feng)(feng)的(de)(de)半(ban)(ban)圓(yuan)弧所(suo)受的(de)(de)拉應(ying)(ying)力(li)與(yu)(yu)其下(xia)(xia)方(fang)波(bo)(bo)(bo)峰(feng)(feng)的(de)(de)半(ban)(ban)圓(yuan)弧所(suo)受的(de)(de)壓應(ying)(ying)力(li)相等(deng),以,DD'依然平行于(yu)CC

PP波(bo)(bo)紋管(guan)(guan)在(zai)橫向上受(shou)到力的(de)(de)作(zuo)用之(zhi)后,必(bi)然產生彎曲變(bian)(bian)形(xing),變(bian)(bian)形(xing)的(de)(de)主(zhu)要部位就是(shi)圓(yuan)(yuan)環(huan)(huan)膜(mo)(mo)片(pian)(pian)(pian)。凹面向心(xin)和(he)凹面背(bei)心(xin)的(de)(de)兩(liang)個半(ban)(ban)(ban)圓(yuan)(yuan)弧從軸向剖(pou)面圖上來看,它稱(cheng)作(zuo)波(bo)(bo)峰和(he)波(bo)(bo)谷(gu))剛性大(da)(da),它與圓(yuan)(yuan)環(huan)(huan)膜(mo)(mo)片(pian)(pian)(pian)相(xiang)比,變(bian)(bian)形(xing)極小。也就是(shi)說,凹面向心(xin)和(he)凹面背(bei)心(xin)的(de)(de)半(ban)(ban)(ban)圓(yuan)(yuan)弧的(de)(de)小半(ban)(ban)(ban)徑(jing)(jing)以(yi)(yi)及連接它們的(de)(de)圓(yuan)(yuan)環(huan)(huan)膜(mo)(mo)片(pian)(pian)(pian)的(de)(de)內、外半(ban)(ban)(ban)徑(jing)(jing)差,這(zhe)兩(liang)個參數(shu)與變(bian)(bian)形(xing)有著直接的(de)(de)關系。但由于制(zhi)造工(gong)藝上的(de)(de)困難,一定通徑(jing)(jing)的(de)(de)PE波(bo)(bo)紋管(guan)(guan)的(de)(de)波(bo)(bo)紋高(gao)度(du)將受(shou)到其最大(da)(da)值(zhi)的(de)(de)限(xian)制(zhi)。這(zhe)就是(shi)說,波(bo)(bo)峰和(he)波(bo)(bo)谷(gu)半(ban)(ban)(ban)圓(yuan)(yuan)弧的(de)(de)小半(ban)(ban)(ban)徑(jing)(jing)及圓(yuan)(yuan)環(huan)(huan)膜(mo)(mo)片(pian)(pian)(pian)的(de)(de)內、外半(ban)(ban)(ban)徑(jing)(jing)之(zhi)差這(zhe)兩(liang)個值(zhi)的(de)(de)確定,是(shi)以(yi)(yi)通徑(jing)(jing)大(da)(da)小為基礎的(de)(de)。從這(zhe)個意義(yi)上來看,通徑(jing)(jing)大(da)(da)小是(shi)影響金屬波(bo)(bo)紋管(guan)(guan)變(bian)(bian)形(xing)的(de)(de)主(zhu)要因素。

PP波(bo)(bo)紋(wen)(wen)管(guan)(guan)(guan)以(yi)圓片翹(qiao)曲理論為基(ji)礎確定波(bo)(bo)紋(wen)(wen)管(guan)(guan)(guan)的(de)(de)(de)縱向(xiang)剛(gang)度(du)金屬波(bo)(bo)紋(wen)(wen)管(guan)(guan)(guan)的(de)(de)(de)結構特(te)點說明了它在受到軸向(xiang)力的(de)(de)(de)作用之(zhi)后,各部分(fen)很容易產(chan)生(sheng)彈性變形。PE波(bo)(bo)紋(wen)(wen)管(guan)(guan)(guan)由于波(bo)(bo)峰半(ban)(ban)圓弧(hu)和波(bo)(bo)谷半(ban)(ban)圓弧(hu)這兩部分(fen)的(de)(de)(de)相對變形遠遠小(xiao)于圓環(huan)膜片部分(fen)因此,可以(yi)忽略不(bu)計,并把它們視為圓環(huan)膜片與圓環(huan)膜片之(zhi)間的(de)(de)(de)剛(gang)性接點。把波(bo)(bo)紋(wen)(wen)管(guan)(guan)(guan)復雜的(de)(de)(de)受力狀態簡化(hua)為圓環(huan)膜片單(dan)一受力的(de)(de)(de)形式。這樣,便(bian)可以(yi)用圖片翹(qiao)曲理論為基(ji)礎去分(fen)析整個(ge)波(bo)(bo)紋(wen)(wen)管(guan)(guan)(guan)的(de)(de)(de)縱向(xiang)剛(gang)度(du)

PE波(bo)紋管(guan)給水管(guan)道的(de)基(ji)礎用來防止管(guan)道不均勻(yun)沉陷造成管(guan)道破裂或接口(kou)損(sun)壞而(er)漏水。般情況(kuang)下有三種基(ji)礎。當管(guan)底地(di)(di)基(ji)土(tu)層承(cheng)載力較(jiao)高，地(di)(di)下水位(wei)較(jiao)低(di)時(shi)，可采(cai)用天(tian)(tian)然地(di)(di)基(ji)作為PP波(bo)紋管(guan)管(guan)道基(ji)礎。施(shi)工(gong)時(shi)，將(jiang)天(tian)(tian)然地(di)(di)基(ji)整平(ping)，管(guan)道鋪設在未經擾動的(de)原狀土(tu)上即可，如(ru)圖(tu)1.3.9(a) 所示。為安全起見，可將(jiang)天(tian)(tian)然地(di)(di)基(ji)夯實后再鋪設管(guan)道;為保(bao)證管(guan)道鋪設的(de)位(wei)置正確，可將(jiang)槽(cao)底做成90°~ 135*的(de)弧(hu)形槽(cao)。