一、砂石墊層的施工要求有哪些
1、砂石墊層的材料必須具有良好的振實加密性能,宜選用碎石、卵石、角礫、圓礫、礫砂、粗砂、中(zhong)砂或(huo)石屑(粒(li)徑小(xiao)于2mm的(de)部分(fen)不應超過(guo)總重(zhong)的(de)45%),且應級配良好,不含植(zhi)物(wu)殘體、垃圾等(deng)雜物(wu)。若只(zhi)用(yong)粉(fen)細砂或(huo)石粉(fen)(粒(li)徑小(xiao)于0.075 mm的(de)部分(fen)不超過(guo)總重(zhong)的(de)90%)時,應均勻摻入不少于總重(zhong)30%的(de)碎石或(huo)卵石。砂石的(de)最大(da)粒(li)徑不宜(yi)大(da)于50mm。
2、基(ji)坑(keng)(keng)開挖時應避免(mian)坑(keng)(keng)底(di)土(tu)(tu)(tu)(tu)層(ceng)受擾(rao)動(dong)(dong),可保(bao)留約200mm厚(hou)(hou)的(de)(de)土(tu)(tu)(tu)(tu)層(ceng)暫(zan)不挖去(qu),待鋪(pu)填墊(dian)(dian)(dian)層(ceng)前再挖至設(she)計標(biao)高。嚴(yan)禁擾(rao)動(dong)(dong)墊(dian)(dian)(dian)層(ceng)下的(de)(de)軟弱土(tu)(tu)(tu)(tu)層(ceng),防止其被踐踏、受凍或受水(shui)(shui)浸(jin)泡(pao)。在(zai)碎石(shi)墊(dian)(dian)(dian)層(ceng)底(di)部(bu)宜設(she)置(zhi)150~300mm厚(hou)(hou)的(de)(de)砂墊(dian)(dian)(dian)層(ceng)或鋪(pu)一層(ceng)土(tu)(tu)(tu)(tu)工(gong)織物,以(yi)防止軟弱土(tu)(tu)(tu)(tu)層(ceng)表面的(de)(de)局(ju)部(bu)破(po)壞,同時必須防止基(ji)坑(keng)(keng)邊坡(po)坍土(tu)(tu)(tu)(tu)混(hun)入墊(dian)(dian)(dian)層(ceng)。在(zai)地(di)下水(shui)(shui)位(wei)以(yi)下施(shi)工(gong)時,應采(cai)取降(jiang)低地(di)下水(shui)(shui)位(wei)的(de)(de)措施(shi)(水(shui)(shui)撼(han)法施(shi)工(gong)除外),使基(ji)坑(keng)(keng)保(bao)持無積水(shui)(shui)狀態。如因墊(dian)(dian)(dian)層(ceng)下方(fang)土(tu)(tu)(tu)(tu)質(zhi)差異而(er)使墊(dian)(dian)(dian)層(ceng)底(di)面標(biao)高不一時,基(ji)坑(keng)(keng)(槽)底(di)宜挖成(cheng)階梯形(xing),施(shi)工(gong)時按(an)先深后淺(qian)的(de)(de)順序進行(xing),并應注意(yi)搭接處的(de)(de)質(zhi)量(liang)。
3、砂(sha)(sha)(sha)石(shi)(shi)墊層(ceng)(ceng)施工(gong)(gong)的(de)(de)(de)關(guan)鍵(jian)是(shi)將砂(sha)(sha)(sha)石(shi)(shi)材(cai)料(liao)振(zhen)實(shi)(shi)(shi)加密(mi)到設計要(yao)求的(de)(de)(de)密(mi)實(shi)(shi)(shi)度(du)(du)(壓實(shi)(shi)(shi)系數0.94~0.97)。如(ru)要(yao)求進(jin)一步提高砂(sha)(sha)(sha)石(shi)(shi)墊層(ceng)(ceng)的(de)(de)(de)質(zhi)(zhi)量,則宜加大(da)機械的(de)(de)(de)功率。砂(sha)(sha)(sha)石(shi)(shi)墊層(ceng)(ceng)的(de)(de)(de)施工(gong)(gong)方(fang)法(fa)有(you)振(zhen)實(shi)(shi)(shi)法(fa)、水撼法(fa)、夯實(shi)(shi)(shi)法(fa)、碾(nian)壓法(fa)等(deng)多種,可根據砂(sha)(sha)(sha)石(shi)(shi)材(cai)料(liao)、地質(zhi)(zhi)條(tiao)件、施工(gong)(gong)設備等(deng)條(tiao)件選用(yong)。施工(gong)(gong)時應分層(ceng)(ceng)鋪筑,在下層(ceng)(ceng)的(de)(de)(de)密(mi)實(shi)(shi)(shi)度(du)(du)經檢(jian)驗(yan)達到合(he)格要(yao)求后(hou),方(fang)可進(jin)行上層(ceng)(ceng)施工(gong)(gong)。砂(sha)(sha)(sha)墊層(ceng)(ceng)施工(gong)(gong)時的(de)(de)(de)含(han)水量對壓實(shi)(shi)(shi)效果(guo)(guo)影響很大(da),一般以(yi)潤濕到接近飽和狀(zhuang)態時效果(guo)(guo)最(zui)好(hao)。
二、砂石墊層成品有哪些保護措施
1、施(shi)工時(shi)應妥(tuo)善(shan)保護標(biao)高控制(zhi)樁(zhuang),防止碰撞位移,并應經常復測。
2、對伸出墻(qiang)的(de)(de)設備管(guan)線(xian)、埋入(ru)墊層中的(de)(de)各種管(guan)線(xian)均應(ying)妥善保護,防止施工(gong)時碰撞(zhuang)或(huo)損(sun)壞。
3、施工中遇(yu)雨、雪(xue)天(tian)要做臨時覆(fu)蓋,以(yi)防(fang)墊(dian)層被浸泡(pao)或受凍(dong)。
4、墊層(ceng)施(shi)工完后(hou),應及時進行下道工序(xu)施(shi)工,否則(ze),應進行圍擋和臨時遮蓋.并經常灑水濕潤(run)。
5、施工完的(de)墊層不(bu)得在上堆放(fang)重物和行(xing)駛(shi)車輛。