土木工程類專業(yè)英文文獻(xiàn)及翻譯-免費(fèi)閱讀
【正文】 亞利桑那州的土壤通常有56%的面積比。此外，在現(xiàn)場(chǎng)試驗(yàn)取得的飽和度是變化的，通常也不能確定。鑒別濕陷性土已經(jīng)有許多技術(shù)，提出了鑒別濕陷性土的問(wèn)題。這樣，如果提供給土壤水量高于自然狀態(tài)水量，可能在較低水平的壓力時(shí)就發(fā)生崩潰，或許就在上覆土壓力作用下。在干旱地區(qū)，有很高的蒸發(fā)量，而降水量較低。這種土的形成過(guò)程以及計(jì)算可能發(fā)生的體積變化量將在下文中介紹。然而，最好的和最合理的設(shè)計(jì)可能會(huì)具有更大的經(jīng)濟(jì)優(yōu)勢(shì)相比于可靠的體積變化預(yù)測(cè)。對(duì)典型的路面路基提供了一種方法去預(yù)測(cè)相關(guān)的應(yīng)力和相應(yīng)的濕陷張力。PAVEMENT PROBLEMS CAUSEDBY COLLAPSIBLE SUBGRADESBy Sandra L. Houston,1 Associate Member, ASCE(Reviewed by the Highway Division)ABSTRACT: Problem subgrade materials consisting of collapsible soils are mon in arid environments, which have climatic conditions and depositional andweathering processes favorable to their formation. Included herein is a discussionof predictive techniques that use monly available laboratory equipment andtesting methods for obtaining reliable estimates of the volume change for theseproblem soils. A method for predicting relevant stresses and corresponding collapsestrains for typical pavement subgrades is presented. Relatively simple methods ofevaluating potential volume change, based on results of familiar laboratory tests,are used.INTRODUCTIONWhen a soil is given free access to water, it may decrease in volume,increase in volume, or do nothing. A soil that increases in volume is calleda swelling or expansive soil, and a soil that decreases in volume is called acollapsible soil. The amount of volume change that occurs depends on thesoil type and structure, the initial soil density, the imposed stress state, andthe degree and extent of wetting. Subgrade materials prised of soils thatchange volume upon wetting have caused distress to highways since the beginning of the professional practice and have cost many millions of dollarsin roadway repairs. The prediction of the volume changes that may occur inthe field is the first step in making an economic decision for dealing withthese problem subgrade materials.Each project will have different design considerations, economic constraints, and risk factors that will have to be taken into account. However,with a reliable method for making volume change predictions, the best designrelative to the subgrade soils bees a matter of economic parison, anda much more rational design approach may be made. For example, typicaltechniques for dealing with expansive clays include: (1) In situ treatmentswith substances such as lime, cement, or flyash?；谑煜さ膶?shí)驗(yàn)室測(cè)試結(jié)果，使用相對(duì)簡(jiǎn)單的方法評(píng)估潛在體積的變化。例如，典型的處理膨脹黏土的技術(shù)有：(1)在現(xiàn)場(chǎng)用例如石灰、粉煤灰或者水泥等處置處理；(2)設(shè)置滲流屏障或者排水設(shè)施；(3)進(jìn)行適用性散失的計(jì)算來(lái)變更設(shè)計(jì)來(lái)接受預(yù)期膨脹。美國(guó)亞利桑那州皇家經(jīng)濟(jì)學(xué)會(huì)高級(jí)助理教授Tempe注：討論開(kāi)放至1989年4月1日。因此，當(dāng)有降水時(shí)只有地面土壤濕潤(rùn)。額外的負(fù)荷，如交通荷載或橋梁結(jié)構(gòu)的存在，
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