電話： 郵(you)箱(xiang)：
當管(guan)(guan)(guan)底(di)為巖石(shi)(shi)、碎石(shi)(shi)或(huo)多(duo)石(shi)(shi)地基(ji)時(shi)，對(dui)(dui)金(jin)屬管(guan)(guan)(guan)道(dao)應鋪(pu)墊不(bu)小(xiao)于(yu)100 mm厚的中砂(sha)(sha)或(huo)粗(cu)砂(sha)(sha)，對(dui)(dui)非金(jin)屬管(guan)(guan)(guan)道(dao)應鋪(pu)墊不(bu)小(xiao)于(yu)150 mm厚的中砂(sha)(sha)或(huo)粗(cu)砂(sha)(sha)，構(gou)成砂(sha)(sha)基(ji)礎(chu)，再在(zai)上面鋪(pu)設(she)管(guan)(guan)(guan)道(dao)，如圖1.3.9(b)所(suo)示。當管(guan)(guan)(guan)底(di)地基(ji)土(tu)(tu)質松軟(ruan)，承(cheng)載(zai)力低(di)(di)或(huo)鋪(pu)設(she)大管(guan)(guan)(guan)徑的鋼筋(jin)混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)管(guan)(guan)(guan)道(dao)時(shi)，應采(cai)用(yong)混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)基(ji)礎(chu)。根據地基(ji)承(cheng)載(zai)力的實際情況，可采(cai)用(yong)強度等級不(bu)低(di)(di)于(yu)C10的混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)帶形基(ji)礎(chu),也可采(cai)用(yong)混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)枕基(ji)，如圖1.3.9 (c)所(suo)示。混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)帶形基(ji)礎(chu)是沿管(guan)(guan)(guan)道(dao)全(quan)長做(zuo)成的基(ji)礎(chu)，而(er)混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)枕基(ji)是只在(zai)管(guan)(guan)(guan)道(dao)接(jie)口(kou)處用(yong)混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)塊墊起，其他地方用(yong)中砂(sha)(sha)或(huo)粗(cu)砂(sha)(sha)填實。對(dui)(dui)混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)基(ji)礎(chu)，如管(guan)(guan)(guan)道(dao)采(cai)用(yong)柔性接(jie)口(kou)，應每(mei)隔(ge)一定距(ju)離在(zai)柔性接(jie)口(kou)下，留出600~800mm的范圍不(bu)澆(jiao)筑混(hun)凝(ning)(ning)(ning)(ning)(ning)土(tu)(tu)，而(er)
PP波(bo)紋管 象研究梁(liang)的(de)(de)變(bian)形一樣,我(wo)們從(cong)純彎(wan)曲(qu)的(de)(de)情(qing)況著手,假設彎(wan)曲(qu)狀態(tai)下(xia)的(de)(de)金屬波(bo)紋管的(de)(de)軸向剖(pou)面上(shang)取半(ban)(ban)(ban)個波(bo)峰寬(kuan)度和半(ban)(ban)(ban)個波(bo)谷寬(kuan)度作為微(wei)量,從(cong)其(qi)通徑和波(bo)紋幾(ji)何形狀上(shang)去分析(見圖4-1)。常態(tai)下(xia)的(de)(de)全屬波(bo)紋管,AA、BB′、CC'、DD都是互相平行的(de)(de)。PE波(bo)紋管彎(wan)曲(qu)之后,軸心(xin)線EG變(bian)成了撓(nao)曲(qu)線。由于(yu)撓(nao)曲(qu)線上(shang)方(fang)(fang)的(de)(de)波(bo)谷的(de)(de)半(ban)(ban)(ban)圓(yuan)弧所受(shou)拉應力與(yu)其(qi)下(xia)方(fang)(fang)波(bo)谷的(de)(de)半(ban)(ban)(ban)圓(yuan)弧所受(shou)壓應力相等(deng),所以,BB依(yi)然平行于(yu)AA;由于(yu)撓(nao)曲(qu)線上(shang)方(fang)(fang)的(de)(de)波(bo)峰的(de)(de)半(ban)(ban)(ban)圓(yuan)弧所受(shou)的(de)(de)拉應力與(yu)其(qi)下(xia)方(fang)(fang)波(bo)峰的(de)(de)半(ban)(ban)(ban)圓(yuan)弧所受(shou)的(de)(de)壓應力相等(deng),以,DD'依(yi)然平行于(yu)CC
PP波(bo)紋(wen)(wen)(wen)管(guan)在(zai)橫向(xiang)上受到力的(de)(de)(de)作用之后,必然產生(sheng)彎曲變形(xing)(xing),變形(xing)(xing)的(de)(de)(de)主要部位就(jiu)是圓(yuan)(yuan)環(huan)膜(mo)(mo)片(pian)。凹(ao)(ao)面(mian)(mian)向(xiang)心(xin)(xin)和凹(ao)(ao)面(mian)(mian)背心(xin)(xin)的(de)(de)(de)兩個(ge)半(ban)(ban)(ban)圓(yuan)(yuan)弧(hu)從(cong)軸向(xiang)剖面(mian)(mian)圖(tu)上來看(kan),它稱作波(bo)峰和波(bo)谷)剛(gang)性(xing)大(da),它與圓(yuan)(yuan)環(huan)膜(mo)(mo)片(pian)相比,變形(xing)(xing)極小(xiao)。也就(jiu)是說,凹(ao)(ao)面(mian)(mian)向(xiang)心(xin)(xin)和凹(ao)(ao)面(mian)(mian)背心(xin)(xin)的(de)(de)(de)半(ban)(ban)(ban)圓(yuan)(yuan)弧(hu)的(de)(de)(de)小(xiao)半(ban)(ban)(ban)徑(jing)(jing)以及(ji)連接它們的(de)(de)(de)圓(yuan)(yuan)環(huan)膜(mo)(mo)片(pian)的(de)(de)(de)內(nei)、外半(ban)(ban)(ban)徑(jing)(jing)差(cha),這兩個(ge)參數與變形(xing)(xing)有著直接的(de)(de)(de)關系。但由于制造工藝上的(de)(de)(de)困(kun)難,一定通徑(jing)(jing)的(de)(de)(de)PE波(bo)紋(wen)(wen)(wen)管(guan)的(de)(de)(de)波(bo)紋(wen)(wen)(wen)高度將受到其最大(da)值(zhi)的(de)(de)(de)限制。這就(jiu)是說,波(bo)峰和波(bo)谷半(ban)(ban)(ban)圓(yuan)(yuan)弧(hu)的(de)(de)(de)小(xiao)半(ban)(ban)(ban)徑(jing)(jing)及(ji)圓(yuan)(yuan)環(huan)膜(mo)(mo)片(pian)的(de)(de)(de)內(nei)、外半(ban)(ban)(ban)徑(jing)(jing)之差(cha)這兩個(ge)值(zhi)的(de)(de)(de)確定,是以通徑(jing)(jing)大(da)小(xiao)為基(ji)礎的(de)(de)(de)。從(cong)這個(ge)意義上來看(kan),通徑(jing)(jing)大(da)小(xiao)是影響金屬波(bo)紋(wen)(wen)(wen)管(guan)變形(xing)(xing)的(de)(de)(de)主要因素。
PP波(bo)紋管以(yi)圓片(pian)(pian)(pian)翹(qiao)曲理論為(wei)基礎確(que)定波(bo)紋管的(de)(de)縱(zong)向剛度金(jin)屬波(bo)紋管的(de)(de)結構特(te)點(dian)說明了它在受(shou)(shou)到軸(zhou)向力(li)的(de)(de)作用之后,各部分很容易產生(sheng)彈性變形(xing)(xing)。PE波(bo)紋管由于波(bo)峰半圓弧和(he)波(bo)谷半圓弧這(zhe)兩部分的(de)(de)相對變形(xing)(xing)遠遠小于圓環(huan)(huan)膜片(pian)(pian)(pian)部分因(yin)此,可以(yi)忽略(lve)不計,并把它們視為(wei)圓環(huan)(huan)膜片(pian)(pian)(pian)與(yu)圓環(huan)(huan)膜片(pian)(pian)(pian)之間的(de)(de)剛性接點(dian)。把波(bo)紋管復(fu)雜(za)的(de)(de)受(shou)(shou)力(li)狀(zhuang)態簡(jian)化為(wei)圓環(huan)(huan)膜片(pian)(pian)(pian)單一受(shou)(shou)力(li)的(de)(de)形(xing)(xing)式。這(zhe)樣,便可以(yi)用圖(tu)片(pian)(pian)(pian)翹(qiao)曲理論為(wei)基礎去分析整個波(bo)紋管的(de)(de)縱(zong)向剛度
PE波(bo)紋管(guan)(guan)(guan)(guan)給水(shui)管(guan)(guan)(guan)(guan)道(dao)(dao)的(de)基(ji)礎(chu)用來防止管(guan)(guan)(guan)(guan)道(dao)(dao)不(bu)均勻沉(chen)陷造成管(guan)(guan)(guan)(guan)道(dao)(dao)破裂或(huo)接口損壞而漏水(shui)。般情(qing)況(kuang)下(xia)有三種基(ji)礎(chu)。當管(guan)(guan)(guan)(guan)底地基(ji)土層承載力較(jiao)高，地下(xia)水(shui)位較(jiao)低(di)時(shi)，可(ke)采用天(tian)(tian)然地基(ji)作為PP波(bo)紋管(guan)(guan)(guan)(guan)管(guan)(guan)(guan)(guan)道(dao)(dao)基(ji)礎(chu)。施工時(shi)，將天(tian)(tian)然地基(ji)整(zheng)平，管(guan)(guan)(guan)(guan)道(dao)(dao)鋪設(she)在未經(jing)擾動(dong)的(de)原狀(zhuang)土上(shang)即可(ke)，如圖1.3.9(a) 所示。為安全起(qi)見(jian)，可(ke)將天(tian)(tian)然地基(ji)夯實后再鋪設(she)管(guan)(guan)(guan)(guan)道(dao)(dao);為保證管(guan)(guan)(guan)(guan)道(dao)(dao)鋪設(she)的(de)位置正確(que)，可(ke)將槽底做成90°~ 135*的(de)弧(hu)形槽。
