真空預壓沉降監測

真(zhen)(zhen)空(kong)(kong)(kong)(kong)預(yu)壓法(fa)就是在(zai)(zai)需要(yao)加(jia)(jia)固(gu)(gu)的軟基(ji)中插入豎(shu)向(xiang)(xiang)(xiang)排(pai)(pai)(pai)(pai)水(shui)通道(dao)(dao)（如砂(sha)(sha)(sha)井、袋裝(zhuang)砂(sha)(sha)(sha)井或(huo)塑料排(pai)(pai)(pai)(pai)水(shui)板(ban)等），然(ran)后在(zai)(zai)地(di)面(mian)鋪(pu)設(she)(she)一(yi)(yi)(yi)層(ceng)(ceng)砂(sha)(sha)(sha)墊層(ceng)(ceng)，再在(zai)(zai)其上(shang)覆蓋一(yi)(yi)(yi)層(ceng)(ceng)不透氣(qi)的薄(bo)膜。在(zai)(zai)膜下抽真(zhen)(zhen)空(kong)(kong)(kong)(kong)形成負(fu)(fu)(fu)(fu)壓（相對大氣(qi)壓而言)），負(fu)(fu)(fu)(fu)壓沿豎(shu)向(xiang)(xiang)(xiang)排(pai)(pai)(pai)(pai)水(shui)通道(dao)(dao)向(xiang)(xiang)(xiang)下傳(chuan)(chuan)遞 土(tu)體(ti)與豎(shu)向(xiang)(xiang)(xiang)排(pai)(pai)(pai)(pai)水(shui)通道(dao)(dao)的不等壓狀態又使負(fu)(fu)(fu)(fu)壓向(xiang)(xiang)(xiang)土(tu)體(ti)中傳(chuan)(chuan)遞，在(zai)(zai)負(fu)(fu)(fu)(fu)壓作用(yong)(yong)下，孔隙水(shui)逐漸滲流到(dao)豎(shu)向(xiang)(xiang)(xiang)排(pai)(pai)(pai)(pai)水(shui)通道(dao)(dao)中而達到(dao)土(tu)體(ti)排(pai)(pai)(pai)(pai)水(shui)固(gu)(gu)結(jie)、強(qiang)度增長的效果。真(zhen)(zhen)空(kong)(kong)(kong)(kong)預(yu)壓法(fa)作為新(xin)一(yi)(yi)(yi)代軟基(ji)加(jia)(jia)固(gu)(gu)方(fang)法(fa)，以其工(gong)期短、施(shi)(shi)工(gong)安(an)全、無污染環(huan)境、費用(yong)(yong)低等優點而廣(guang)泛應用(yong)(yong)于港口、碼頭(tou)、機場、工(gong)業與民用(yong)(yong)建(jian)筑等工(gong)程建(jian)設(she)(she)，但(dan)理論研(yan)究的落(luo)后限(xian)制了其工(gong)程上(shang)的進一(yi)(yi)(yi)步推廣(guang)應用(yong)(yong)。用(yong)(yong)真(zhen)(zhen)空(kong)(kong)(kong)(kong)預(yu)壓加(jia)(jia)固(gu)(gu)軟土(tu)地(di)基(ji)，在(zai)(zai)固(gu)(gu)結(jie)過程中不僅土(tu)體(ti)產生(sheng)垂(chui)直沉降，側向(xiang)(xiang)(xiang)也會產生(sheng)向(xiang)(xiang)(xiang)著負(fu)(fu)(fu)(fu)壓源(yuan)的水(shui)平位(wei)移。當在(zai)(zai)真(zhen)(zhen)空(kong)(kong)(kong)(kong)預(yu)壓的影響(xiang)范圍內有其他建(jian)筑設(she)(she)施(shi)(shi)時(shi)，使用(yong)(yong)該法(fa)可能(neng)會危及(ji)其上(shang)部(bu)結(jie)構物的安(an)全。真(zhen)(zhen)空(kong)(kong)(kong)(kong)預(yu)壓法(fa)施(shi)(shi)工(gong)流程如下：測量(liang)放線→鋪(pu)設(she)(she)主支濾排(pai)(pai)(pai)(pai)水(shui)管→鋪(pu)設(she)(she)上(shang)層(ceng)(ceng)砂(sha)(sha)(sha)墊層(ceng)(ceng)→砂(sha)(sha)(sha)面(mian)整(zheng)平→鋪(pu)設(she)(she)聚氯(lv)乙烯薄(bo)膜→施(shi)(shi)工(gong)密封溝→設(she)(she)置測量(liang)標志→安(an)裝(zhuang)真(zhen)(zhen)空(kong)(kong)(kong)(kong)泵→抽真(zhen)(zhen)空(kong)(kong)(kong)(kong)預(yu)壓固(gu)(gu)結(jie)土(tu)層(ceng)(ceng)。