【正文】 較薄，為保證構(gòu)件的幾何尺寸，常 采用內(nèi)外螺栓拉接的措施，需要注意的是 ，應(yīng)在拉接螺栓中間設(shè)置止水鐵板 ，以防止水沿著螺栓滲漏，形成引水通路。 3)施工過(guò)程中應(yīng)定期抽查測(cè)定混凝土坍落度，施工中如遇下 雨或其他原因，砂石含水量發(fā)生變化時(shí)，應(yīng)及時(shí)測(cè)定其含水率，并 7 調(diào)整施工配合比。 為防止水泥漿與 骨料分離，防水混凝土下料時(shí)自由高度應(yīng)不超過(guò)防水結(jié) 構(gòu)鋼筋密集，當(dāng)澆筑高度較高時(shí) ，應(yīng)按規(guī)定在模板上開(kāi)門(mén)子下料或用串桶 (溜槽 )下料，防止水泥漿與骨料分離，同時(shí)也避免水泥 漿或混凝土松散地堆積于鋼筋交叉處和水泥漿濺粘于模板表面，既造成后面下料困難 ，又影響結(jié)構(gòu)表面光滑，成為日后滲漏隱患。防水混凝土一般在垂直方向不留置施工縫，在主樓與裙樓之 間設(shè)了后澆帶，垂直方向的施工縫在接縫部位設(shè)置膨脹性橡膠止 水帶或鋼板止水帶。首先應(yīng)重視回填土本身的質(zhì)量；其次回填前應(yīng)清理 坑底的雜物和積水 ，回填時(shí)應(yīng)分層夯實(shí)。t be ignored on the stress state of the structure. We meet to construct temperature crack in mainly, so only to origin cause of formation and treatment measure, concrete of crack make a discussion in constructing this text. Reason of a crack 10 Have many kinds of reasons to produce the crack in the concrete, it is mainly the changes of temperature and humidity, fragility and disparity of the concrete, and the structure is unreasonable, the raw materials is not up to standard (if the alkali aggregate react), the template is out of shape, the foundation does not subside etc. evenly . The cement emits a large amount of heat of hydration when the concrete is hardenned, inside temperature is rising constantly, cause the stress of drawing on the surface. In the course of lowering the temperature , is it congeal foundation pay restrain to mix always later stage, will present the stress of drawing within the concrete . Reducing of temperature can surface cause heavy stress of drawing very in concrete too. When these draw the stress and go beyond resisting the ability of splitting of concrete , namely will present the crack . A lot of inside humidity of concrete change very light or change relatively slow, surface humidity might change heavy the violent change takes placing. Such as maintaining thoroughly, when getting wetter when not doing,contract surface there aren39。 (5)Stipulate rational form removal time, the temperature keeps warm the surface while lowering suddenly, in case that the rapid temperature gradient takes place in the concrete surface。s had guarded against reinforced bar protective layer deviation piece big mass mon failings. The concrete stirring and mixing makes and transports Since the waterproof concrete requires that higher closely knit , reason why stir and mix system also need to have the fairly good homogeneity , should be ready for burning as follows almost for this purpose 1) ensures that mixing time , mixing at every time are secondary jump into a expect the general ejection of pact block of wood less than 2 mins. 2) should use the apposition agent , the solution queen who should manufacture certain thickness from apposition agent adds the mixer inner, the dried powder or high concentration solution will add an agent extra not to adds the mixer inner directly ,prevent from mixing is uneven but part concentrates, both lose the apposition agent effect, and affect concrete mass. 3) responds to the assured source of life degree having a spot test on the admeasurement concrete at the regular intervals collapsing in the process being under construction , construction is middle if Yu rains or other cause, respond to the ratio determining whose water ratio, and adjusting the position being under construction in time when change happened in sandstone moisture content. 4) project uses the modity concrete , has boundary have raised a concrete stirring mass and of all kinds effect apposition agent adulterating falls when amounts , the water ash having controlled a concrete strictly collapsing. 5) concretes concrete adopt a pump to have given handicraft , effective avoiding a concrete producing the phenomenon isolating Mi Shui and leaving out thick fluid in the 21 process of transportation. Matters needing attention in being under 。 The measure of improving condition of restraining is: (1)Divide and sew and divide one rationally 。s shoulder or back limit when draw out of shape to have *104 only , is it carry on one39。 在工程地下室工程施工申，由于切切實(shí)實(shí)嚴(yán)把以上七道關(guān)口，組織防水混凝土施工，效果比較理想 ，沒(méi)有出現(xiàn)滲漏水現(xiàn)象。采用止水鋼板時(shí)不得有漏焊，采用橡膠止水帶在接長(zhǎng)時(shí)務(wù)必要將接頭用專(zhuān)用膠水粘貼牢固可靠。 5)認(rèn)真做好接漿措施，及時(shí)調(diào)整坍落度。 5)混凝土的澆筑采用泵送工藝，有效的避免了混凝土在運(yùn)輸過(guò)程中產(chǎn)生離析泌水及漏漿現(xiàn)象。 2)鋼筋接頭應(yīng)盡量采用焊接接頭 ，盡量少用和不用綁扎接頭。但由于蒸發(fā)等原因常引起水分損失，從而推遲或妨礙水泥的水化，表面混凝土最容易而且 直接受到這種不利影響。從溫度應(yīng)力觀點(diǎn)出發(fā)，保溫應(yīng)達(dá)到下述要求： 1）防止混凝土內(nèi)外溫度差及混凝土表面梯度，防止表面裂縫。 （ 5）提高水泥漿與骨料的粘結(jié)力，提高的混凝土抗裂性能。雖然這種裂縫一般都較淺，但它對(duì)結(jié)構(gòu)的強(qiáng)度和耐久性仍有一定的影響。 加筋對(duì)大體積混凝土的溫度應(yīng)力影響很小，因?yàn)榇篌w積混凝土的含筋率極低。在大多數(shù)情況下，需要依靠模型試驗(yàn)或數(shù)值計(jì)算。 （ 3）晚期：混凝土完全冷卻以后的運(yùn)轉(zhuǎn)時(shí)期。在素混凝土內(nèi)或鋼筋混凝上的 2 邊緣部位如果結(jié)構(gòu)內(nèi)出現(xiàn)了拉應(yīng)力，則須依靠混凝土自身承擔(dān)。 混凝土硬化期間水泥放出大量水化熱，內(nèi)部溫度不斷上升，在表面引起拉應(yīng)力。盡管我們?cè)谑┕?中采取各種措施，小心謹(jǐn)慎，但裂縫仍然時(shí)有出現(xiàn)。而在今天，混凝土的裂縫較為普遍，在橋梁工程中裂縫幾乎無(wú)所不在。 裂縫的原因 混凝土中產(chǎn)生裂縫有多種原因，主要是溫度和濕度的變化，混凝土的脆性和不均勻性，以及結(jié)構(gòu)不 合理，原材料不合格（如堿骨料反應(yīng)），模板變形，基礎(chǔ)不均勻沉降等。在鋼筋混凝土中，拉應(yīng)力主要是由鋼筋承擔(dān)，混凝土只是承受壓應(yīng)力。 （ 2）中期：自水泥放熱作用基本結(jié)束時(shí)起至混凝土冷卻到穩(wěn)定溫度時(shí)止，這個(gè)時(shí)期中，溫度應(yīng)力主要是由于混凝土的 冷卻及外界氣溫變化所引起，這些應(yīng)力與早期形成的殘余應(yīng)力相疊加，在此期間混凝上的彈性模量變化不大。 要想根據(jù)已知的溫度準(zhǔn)確分析出溫度應(yīng)力的分布、大小是一項(xiàng)比較復(fù)雜的工作。在混凝土澆筑初期，由于水化熱的散發(fā)，表面引起相當(dāng)大的拉應(yīng)力，此時(shí)表面溫度亦較氣溫為高，此時(shí) 拆除模板，表面溫度驟降，必然引起溫度梯度，從而在表面附加一拉應(yīng)力，與水化熱應(yīng)力迭加，再加上混凝土干縮，表面的拉應(yīng)力達(dá)到很大的數(shù)值，就有導(dǎo)致裂縫的危險(xiǎn)，但如果在拆除模板后及時(shí)在表面覆蓋一輕型保溫材料，如泡沫海棉等，對(duì)于防止混凝土表面產(chǎn)生過(guò)大的拉應(yīng)力，具有顯著的效果?；炷梁弯摻罨炷两Y(jié)構(gòu)的表面常常會(huì)發(fā)生細(xì)而淺的裂縫，其中大多數(shù)屬于干縮裂縫。 （ 4）減水防裂劑可以改善水泥漿的稠度，減少混凝土泌水，減少沉縮變形。因此說(shuō)混凝土的保溫對(duì)防止表面早期裂縫尤其重要。 從理論上分析，新澆混凝土中所含水分完全可以滿足水泥水化的要求而有余。 鋼筋制作與綁扎 防水混凝土結(jié)構(gòu)對(duì)鋼筋有如下要求 ： 1)鋼筋應(yīng)盡可能采用螺紋鋼筋 ，增加握裹力和止水能力。 4)本工程使用商品混凝土，有效的提高了混凝土攪拌質(zhì)量及 各類(lèi)外加劑的摻量，嚴(yán)格控制了混凝土水灰比及坍落度。 4)混凝土的振搗是保證混凝土密實(shí)、防滲的重要一環(huán)， 點(diǎn)定量均勻 下料的基礎(chǔ)上，也應(yīng)采取定點(diǎn)振搗，精心操作注意上 下層的銜接，既要防止漏振、欠振，又要防止過(guò)振，特別要禁止用 撬動(dòng)鋼筋或振動(dòng)鋼筋來(lái)助振的方法，這樣將使前面已澆筑振實(shí)部 分的鋼筋與混凝土分離，造成嚴(yán)重后果。由于施工縫是防水結(jié)構(gòu)的一個(gè)薄弱環(huán) 節(jié)，施工中應(yīng)專(zhuān)人負(fù)責(zé)，精心操作，確保施工質(zhì)量。地下防水結(jié)構(gòu)周?chē)粚? 夯實(shí)的回填土 ，本身是一道可靠而又經(jīng)濟(jì)的防水帷幕。t deformation doing, often cause the crack too. The concrete is a kind of fragility material , tensile strength is about 1/10 of the pression strength, is it carry on one39。 (6)The concrete with medium and longterm and exposed construction builds a piece of surface or thin wall structure, take the measure of keeping warm in cold seas