堤防工程地質勘察管理論文
時間:2022-06-28 08:24:00
導(dao)語:堤(di)防(fang)工程(cheng)地(di)質勘察管理論(lun)文一文來源(yuan)于網友上傳,不(bu)代表本站觀點(dian),若(ruo)需要原創文章可咨詢(xun)客服老(lao)師,歡迎參考(kao)。
堤防工程建設的基礎是設計,而設計的依據是地質,這是工程建設的常識性問題,不會有什么質疑。然而在實際工作中卻往往并非如此。問題主要出在人們對堤防工程地質勘察工(gong)(gong)(gong)作(zuo)(zuo)的(de)(de)片(pian)面理(li)解或被一(yi)(yi)些假(jia)象所迷(mi)惑,走了兩個極(ji)(ji)(ji)端(duan)(duan)。一(yi)(yi)個極(ji)(ji)(ji)端(duan)(duan)是(shi)過(guo)高(gao)地(di)(di)(di)要(yao)求地(di)(di)(di)質(zhi)(zhi)勘(kan)察能在(zai)(zai)“查明”工(gong)(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)(di)質(zhi)(zhi)條(tiao)件的(de)(de)同時,“準確(que)(que)”地(di)(di)(di)提(ti)供設(she)計(ji)需要(yao)的(de)(de)地(di)(di)(di)質(zhi)(zhi)圖件和堤(di)(di)(di)基巖土體物理(li)力學參(can)數,一(yi)(yi)旦(dan)在(zai)(zai)有限的(de)(de)勘(kan)探(tan)控制工(gong)(gong)(gong)作(zuo)(zuo)量之(zhi)內不能完(wan)全同時達(da)到“查明”和“準確(que)(que)”的(de)(de)要(yao)求時,就立(li)即降低了對地(di)(di)(di)質(zhi)(zhi)勘(kan)察工(gong)(gong)(gong)作(zuo)(zuo)的(de)(de)認(ren)可和重視程(cheng)(cheng)(cheng)度;另一(yi)(yi)個極(ji)(ji)(ji)端(duan)(duan)是(shi)我們(men)的(de)(de)祖先在(zai)(zai)數百年乃至(zhi)上千年來(lai)與洪水搏(bo)斗的(de)(de)歲月里修建的(de)(de)大量堤(di)(di)(di)防(fang)工(gong)(gong)(gong)程(cheng)(cheng)(cheng),卻從來(lai)沒有進行過(guo)任何地(di)(di)(di)質(zhi)(zhi)勘(kan)察工(gong)(gong)(gong)作(zuo)(zuo),許多堤(di)(di)(di)防(fang)工(gong)(gong)(gong)程(cheng)(cheng)(cheng)至(zhi)今也(ye)是(shi)安全的(de)(de)。這兩個極(ji)(ji)(ji)端(duan)(duan),不同程(cheng)(cheng)(cheng)度地(di)(di)(di)影響著堤(di)(di)(di)防(fang)工(gong)(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)(di)質(zhi)(zhi)勘(kan)察工(gong)(gong)(gong)作(zuo)(zuo)的(de)(de)有序開展,在(zai)(zai)大規模(mo)的(de)(de)堤(di)(di)(di)防(fang)工(gong)(gong)(gong)程(cheng)(cheng)(cheng)建設(she)中,難免(mian)存在(zai)(zai)這樣(yang)那樣(yang)的(de)(de)問(wen)題(ti)。為(wei)使堤(di)(di)(di)防(fang)工(gong)(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)(di)質(zhi)(zhi)勘(kan)察工(gong)(gong)(gong)作(zuo)(zuo)能夠科學、客觀、完(wan)整、系(xi)統地(di)(di)(di)為(wei)設(she)計(ji)提(ti)供可靠的(de)(de)地(di)(di)(di)質(zhi)(zhi)資料,我們(men)有責任將近年來(lai)堤(di)(di)(di)防(fang)工(gong)(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)(di)質(zhi)(zhi)勘(kan)察工(gong)(gong)(gong)作(zuo)(zuo)中出現的(de)(de)若干問(wen)題(ti)展示出來(lai),供同行們(men)討(tao)論參(can)考。
1堤防(fang)工程(cheng)地(di)質勘(kan)察的過去(qu)與現(xian)狀
我(wo)國已(yi)建江(jiang)河堤(di)(di)防(fang)(fang)工(gong)(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)總長20余萬(wan)公里(li),98特(te)大(da)(da)洪(hong)(hong)(hong)水(shui)(shui)后尚有(you)大(da)(da)量(liang)堤(di)(di)防(fang)(fang)工(gong)(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)正在(zai)規(gui)劃建設中(zhong)。許多已(yi)建堤(di)(di)防(fang)(fang)工(gong)(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)過去基本(ben)上(shang)沒有(you)進行過真正工(gong)(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)意義(yi)上(shang)的(de)(de)(de)(de)工(gong)(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)(di)質(zhi)勘察,更談不(bu)上(shang)各大(da)(da)江(jiang)河湖海堤(di)(di)防(fang)(fang)工(gong)(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)系統(tong)化規(gui)范性的(de)(de)(de)(de)地(di)(di)(di)質(zhi)資(zi)(zi)料(liao)的(de)(de)(de)(de)匯編與分析整理工(gong)(gong)(gong)(gong)(gong)作。正因(yin)為(wei)如此(ci),許多堤(di)(di)防(fang)(fang)工(gong)(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)在(zai)98特(te)大(da)(da)洪(hong)(hong)(hong)水(shui)(shui)期間(jian)險(xian)象環生,出(chu)險(xian)堤(di)(di)段堤(di)(di)基的(de)(de)(de)(de)地(di)(di)(di)質(zhi)條(tiao)件(jian)沒有(you)足夠的(de)(de)(de)(de)資(zi)(zi)料(liao)可供搶(qiang)險(xian)分析,為(wei)確保萬(wan)無一(yi)失,只能按最壞情(qing)況(kuang)進行搶(qiang)險(xian),其人(ren)力物(wu)力的(de)(de)(de)(de)巨(ju)大(da)(da)付出(chu)實在(zai)是(shi)不(bu)得已(yi)而為(wei)之;洪(hong)(hong)(hong)水(shui)(shui)期間(jian)上(shang)至中(zhong)央下(xia)到地(di)(di)(di)方(fang)的(de)(de)(de)(de)各級領導以(yi)及(ji)全國人(ren)民的(de)(de)(de)(de)精神緊(jin)張程(cheng)(cheng)(cheng)度和精力耗費更是(shi)無法用(yong)實物(wu)價(jia)值(zhi)去衡量(liang)。如此(ci)被動(dong)局面(mian)(mian),一(yi)方(fang)面(mian)(mian)是(shi)大(da)(da)自然教訓人(ren)類的(de)(de)(de)(de)生動(dong)一(yi)課,另一(yi)方(fang)面(mian)(mian)則(ze)是(shi)祖先給我(wo)們留下(xia)的(de)(de)(de)(de)世紀難題。
建(jian)國(guo)(guo)以(yi)來,隨著大(da)規(gui)模工(gong)(gong)程(cheng)(cheng)(cheng)建(jian)設(she)(she)(she)的(de)(de)需(xu)要,工(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)質專(zhuan)業(ye)從無到(dao)有(you),日(ri)(ri)益發展壯大(da),成為(wei)國(guo)(guo)家(jia)工(gong)(gong)程(cheng)(cheng)(cheng)建(jian)設(she)(she)(she)不可缺少的(de)(de)重要基(ji)(ji)礎性(xing)專(zhuan)業(ye)。工(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)質勘(kan)察的(de)(de)法(fa)(fa)規(gui)性(xing)準(zhun)(zhun)(zhun)則也逐漸成熟(shu)與(yu)完善(shan),與(yu)工(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)質相關(guan)的(de)(de)規(gui)程(cheng)(cheng)(cheng)規(gui)范相繼出臺(tai),并(bing)結合工(gong)(gong)程(cheng)(cheng)(cheng)實(shi)踐的(de)(de)反饋信息進行修訂修編。水利部(bu)1997年(nian)(nian)2月(yue)了行業(ye)標(biao)(biao)準(zhun)(zhun)(zhun)《堤(di)防(fang)工(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)質勘(kan)察規(gui)程(cheng)(cheng)(cheng)》(以(yi)下簡稱(cheng)《規(gui)程(cheng)(cheng)(cheng)》,編號(hao)SL/T188,同年(nian)(nian)5月(yue)1日(ri)(ri)起實(shi)施),這是(shi)(shi)我國(guo)(guo)堤(di)防(fang)工(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)質勘(kan)察的(de)(de)第(di)一部(bu)法(fa)(fa)規(gui)性(xing)行業(ye)標(biao)(biao)準(zhun)(zhun)(zhun)。而國(guo)(guo)家(jia)標(biao)(biao)準(zhun)(zhun)(zhun)《堤(di)防(fang)工(gong)(gong)程(cheng)(cheng)(cheng)設(she)(she)(she)計規(gui)范》(以(yi)下簡稱(cheng)《規(gui)范》,編號(hao)為(wei)GB50286-98,自1998年(nian)(nian)10月(yue)15日(ri)(ri)起施行)則是(shi)(shi)98特大(da)洪(hong)水之后出臺(tai)的(de)(de)。特大(da)洪(hong)水前后出臺(tai)的(de)(de)這兩部(bu)法(fa)(fa)定標(biao)(biao)準(zhun)(zhun)(zhun)或許是(shi)(shi)歷(li)史的(de)(de)巧(qiao)合,也許是(shi)(shi)歷(li)史的(de)(de)必(bi)(bi)然。巧(qiao)合與(yu)必(bi)(bi)然都說明這樣一個事實(shi):工(gong)(gong)程(cheng)(cheng)(cheng)地(di)(di)質是(shi)(shi)工(gong)(gong)程(cheng)(cheng)(cheng)建(jian)設(she)(she)(she)的(de)(de)基(ji)(ji)礎和(he)偵察兵(bing),具(ju)有(you)超前意識和(he)預見(jian)性(xing),信不信由你(ni)。
《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》頒布前的(de)(de)堤防工(gong)(gong)程(cheng)(cheng)(cheng)(cheng)(cheng)地(di)質(zhi)勘察(cha)工(gong)(gong)作(zuo)基本上沒(mei)有(you)什么(me)標(biao)準。《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》頒布后,地(di)質(zhi)工(gong)(gong)作(zuo)有(you)規(gui)(gui)(gui)(gui)可(ke)循,有(you)法可(ke)依。更為98特大洪水后大規(gui)(gui)(gui)(gui)模堤防建設奠定了(le)基礎。首次頒布此《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》,與(yu)(yu)(yu)工(gong)(gong)程(cheng)(cheng)(cheng)(cheng)(cheng)實際存在(zai)一些差異(yi)再(zai)所難免。《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》實施三(san)年多來(lai),主要存在(zai)三(san)方面的(de)(de)問題,一是《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》本身的(de)(de)實踐性與(yu)(yu)(yu)可(ke)操(cao)作(zuo)性問題;二是地(di)質(zhi)師對(dui)《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》的(de)(de)理解(jie)程(cheng)(cheng)(cheng)(cheng)(cheng)度與(yu)(yu)(yu)把握尺(chi)度;三(san)是人們對(dui)堤防工(gong)(gong)程(cheng)(cheng)(cheng)(cheng)(cheng)地(di)質(zhi)勘察(cha)的(de)(de)認識程(cheng)(cheng)(cheng)(cheng)(cheng)度與(yu)(yu)(yu)理解(jie)程(cheng)(cheng)(cheng)(cheng)(cheng)度。近兩年來(lai),生產(chan)第一線的(de)(de)廣(guang)大地(di)質(zhi)師對(dui)《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》提出(chu)了(le)許多好的(de)(de)意見和(he)建議(yi),我(wo)們在(zai)工(gong)(gong)程(cheng)(cheng)(cheng)(cheng)(cheng)審查過(guo)程(cheng)(cheng)(cheng)(cheng)(cheng)中(zhong),也(ye)在(zai)逐漸地(di)深化對(dui)堤防工(gong)(gong)程(cheng)(cheng)(cheng)(cheng)(cheng)和(he)《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》的(de)(de)理解(jie),力求(qiu)較準確地(di)把握審查尺(chi)度,緊密地(di)與(yu)(yu)(yu)工(gong)(gong)程(cheng)(cheng)(cheng)(cheng)(cheng)實際相結(jie)合(he),避免教(jiao)條和(he)呆板地(di)執行(xing)《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》中(zhong)明顯(xian)與(yu)(yu)(yu)工(gong)(gong)程(cheng)(cheng)(cheng)(cheng)(cheng)實際不(bu)相符合(he)的(de)(de)條款,要求(qiu)客觀地(di)、創(chuang)造性地(di)應用(yong)和(he)執行(xing)《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》,同時也(ye)強(qiang)調(diao)執行(xing)《規(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)(cheng)(cheng)》的(de)(de)嚴肅性。
近年來,堤防(fang)工(gong)程地質勘察工(gong)作基(ji)本上可(ke)以(yi)滿足堤防(fang)工(gong)程設計與施工(gong)的(de)要(yao)求。隨著工(gong)程實踐經驗的(de)積累和(he)對堤防(fang)工(gong)程深層次的(de)認(ren)識與理解,一些具有全局性(xing)和(he)普遍(bian)性(xing)的(de)問題,迫切需要(yao)提(ti)出(chu)來進行討論(lun),以(yi)便引起(qi)足夠的(de)重視(shi)。
2堤(di)防工程隱患與險情分類
2.1分類(lei)的(de)意(yi)義(yi)與原則
堤防(fang)工程(cheng)存在隱(yin)患出現險(xian)(xian)情,導致大洪水(shui)時十分(fen)緊張。大規模的堤防(fang)工程(cheng)建設(she)正(zheng)是(shi)針(zhen)對(dui)隱(yin)患和險(xian)(xian)情而提(ti)出來的“整險(xian)(xian)加(jia)(jia)固(gu)”或“除險(xian)(xian)加(jia)(jia)固(gu)”。顯然(ran),對(dui)隱(yin)患和險(xian)(xian)情實施科學分(fen)類,不僅(jin)是(shi)從實踐上升到理(li)論的成熟過程(cheng),也為堤防(fang)工程(cheng)的勘測設(she)計工作明確(que)了任務,同(tong)時為“加(jia)(jia)固(gu)”工程(cheng)指明方向(xiang),提(ti)供(gong)依據。
在分類之前,我們先給出險情和隱患的定義:
險(xian)(xian)(xian)(xian)情(qing)是指正在發(fa)(fa)生或發(fa)(fa)生過程中被搶險(xian)(xian)(xian)(xian)保(bao)住了的事故堤段,具(ju)有直(zhi)觀性,措(cuo)施(shi)明確性等特點。針(zhen)對險(xian)(xian)(xian)(xian)情(qing),需要分析出險(xian)(xian)(xian)(xian)原因,界定險(xian)(xian)(xian)(xian)情(qing)性質,預測再(zai)次出險(xian)(xian)(xian)(xian)的可能(neng)性,落實工(gong)程措(cuo)施(shi),確保(bao)大堤安(an)全(quan)。
隱(yin)患(huan)是指尚未發(fa)生或可能(neng)將要發(fa)生險情的(de)事故堤段(duan),具有隱(yin)伏(fu)性,隨機性,再生性等特點(dian),更需(xu)要技(ji)術人員的(de)分析判斷(duan),以(yi)便對癥下藥,采取(qu)措施消除(chu)隱(yin)患(huan)。
險情(qing)與隱患(huan)(huan)有明(ming)顯(xian)區別(bie)但又并沒有嚴格的(de)界線,往(wang)往(wang)在(zai)(zai)險情(qing)中(zhong)存在(zai)(zai)著隱患(huan)(huan),在(zai)(zai)隱患(huan)(huan)中(zhong)孕育著險情(qing)。辯證(zheng)地看(kan),險情(qing)是隱患(huan)(huan)發展(zhan)到一(yi)定(ding)程度(du)后的(de)質變(bian)或(huo)(huo)必(bi)然結果,隱患(huan)(huan)是潛藏著的(de)險情(qing)。從過(guo)程時態來看(kan),險情(qing)是現(xian)在(zai)(zai)進行(xing)時或(huo)(huo)過(guo)去(qu)完成時態;隱患(huan)(huan)是過(guo)去(qu)、現(xian)在(zai)(zai)和將來組成的(de)全過(guo)程時態,或(huo)(huo)單(dan)個過(guo)程時態。
本(ben)文(wen)分類的(de)原則主要(yao)體現在(zai)(zai):水工建筑物(wu)(堤(di)(di)身(shen)、穿堤(di)(di)建筑物(wu))與天然地質體(堤(di)(di)基)區別開來,出險(xian)(xian)堤(di)(di)段(duan)(duan)(duan)和(he)存在(zai)(zai)隱(yin)患(huan)(huan)的(de)堤(di)(di)段(duan)(duan)(duan)與非(fei)出險(xian)(xian)堤(di)(di)段(duan)(duan)(duan)和(he)不(bu)存在(zai)(zai)隱(yin)患(huan)(huan)的(de)堤(di)(di)段(duan)(duan)(duan)區別開來,再按險(xian)(xian)情和(he)隱(yin)患(huan)(huan)的(de)性質進一步細化,作為指(zhi)導后(hou)續工作的(de)綱要(yao)。
2.2堤防工程險情分(fen)類
按出險(xian)部位可(ke)分(fen)為(wei)堤基(ji)險(xian)情、崩岸險(xian)情、堤身險(xian)情和穿堤建筑物(wu)險(xian)情,這是出險(xian)時首(shou)先(xian)要(yao)明確的基(ji)本類型(xing)。前兩(liang)類與地質(zhi)(zhi)條件(jian)直接有(you)關,后兩(liang)類與地質(zhi)(zhi)條件(jian)間接有(you)關。可(ke)進一步劃分(fen)如下:
(1)與地質(zhi)條件與河勢(shi)演變均有關(guan)系的險情:崩岸(an)險情,具(ju)有可預見性(xing)、直觀性(xing)、發展性(xing)和多變性(xing)特征。
崩(beng)(beng)岸(an)類險(xian)情(qing)多發生在河(he)流(liu)(liu)凹(ao)岸(an)迎流(liu)(liu)頂沖(chong)或(huo)(huo)深(shen)弘逼(bi)岸(an)區段,地(di)質條件往往是抗沖(chong)刷能(neng)力較差的(de)細砂類土或(huo)(huo)粘性土。由于(yu)河(he)水(shui)位與河(he)勢流(liu)(liu)態的(de)變(bian)化關系,有的(de)崩(beng)(beng)岸(an)險(xian)情(qing)并不發生在洪水(shui)期(高水(shui)位)而是在退水(shui)期(低水(shui)位),因此可以進一步(bu)將崩(beng)(beng)岸(an)險(xian)情(qing)分為洪水(shui)期崩(beng)(beng)岸(an)險(xian)情(qing)和(he)枯水(shui)期崩(beng)(beng)岸(an)險(xian)情(qing),前者(zhe)搶險(xian)緊張,后者(zhe)可以從容(rong)對待。
(2)與地質(zhi)條件直接有(you)關(guan)的(de)險(xian)(xian)情(qing)(主要為堤基險(xian)(xian)情(qing),包括穿堤建筑物地基險(xian)(xian)情(qing)):堤基滲透破(po)壞險(xian)(xian)情(qing)、堤基滑動破(po)壞險(xian)(xian)情(qing)和堤基沉降破(po)壞險(xian)(xian)情(qing)等。
堤基滲(shen)透(tou)破(po)壞(huai)(huai)險情具有(you)一(yi)定的(de)隱(yin)伏性,往往不易準確判(pan)斷,洪水期發生的(de)滲(shen)透(tou)破(po)壞(huai)(huai)實例與(yu)理論計(ji)算有(you)較大出入。另(ling)外,還需注意(yi)將承(cheng)壓水性質的(de)滲(shen)透(tou)破(po)壞(huai)(huai)與(yu)堤基接觸沖刷或砂性土(tu)堤基滲(shen)透(tou)破(po)壞(huai)(huai)區(qu)別開來,因為(wei)滲(shen)透(tou)破(po)壞(huai)(huai)機制不同(tong),工程措施當然(ran)也不一(yi)樣。
存(cun)在滑動或(huo)沉降破(po)壞(huai)(huai)險(xian)情的堤段,堤基(ji)大多分布(bu)有(you)軟弱土層,土體抗剪強度低,壓縮(suo)系數大;另一類滑動或(huo)沉降破(po)壞(huai)(huai)是隨著崩岸險(xian)情而產生的,此類險(xian)情危害最大,搶險(xian)最困難。此外,堤基(ji)內或(huo)堤基(ji)外可能存(cun)在陡坎或(huo)堤坡太(tai)陡,或(huo)堤身填(tian)筑施(shi)工速度太(tai)快,都(dou)可能出現類似破(po)壞(huai)(huai)。
以上險情(qing)實際上也就是我們通常(chang)要求界定明(ming)確的堤防工(gong)程(cheng)(cheng)的三大主要工(gong)程(cheng)(cheng)地質問題:崩岸、滲透破壞(huai)、滑(hua)動或(huo)沉降破壞(huai)。
(3)與地質(zhi)條件基本(ben)無(wu)關(guan)或關(guan)系不大(da)的險(xian)(xian)(xian)情(qing)(qing)(主要為(wei)堤身(shen)(shen)險(xian)(xian)(xian)情(qing)(qing)):堤身(shen)(shen)滲透破(po)壞(huai)(huai)險(xian)(xian)(xian)情(qing)(qing)(與堤身(shen)(shen)質(zhi)量有(you)關(guan),如堤身(shen)(shen)土體的密實(shi)程度、填筑土體的滲透性(xing)質(zhi)和堤身(shen)(shen)單薄等)、堤身(shen)(shen)滑(hua)動破(po)壞(huai)(huai)險(xian)(xian)(xian)情(qing)(qing)和堤身(shen)(shen)沉(chen)降(jiang)破(po)壞(huai)(huai)險(xian)(xian)(xian)情(qing)(qing)等。
2.3堤防(fang)工(gong)程隱患分類
按(an)隱(yin)患存在(zai)的部位可分為:堤(di)身隱(yin)患、穿堤(di)建筑物隱(yin)患和堤(di)基隱(yin)患。
按隱患(huan)的性(xing)質可分(fen)為:常規(gui)性(xing)隱患(huan)和特殊性(xing)隱患(huan)。
常規性(xing)隱(yin)患(huan)(huan):堤(di)(di)身單薄,堤(di)(di)坡太陡,填(tian)筑(zhu)(zhu)質量差(cha),填(tian)筑(zhu)(zhu)體中存(cun)(cun)在(zai)(zai)砂(sha)性(xing)土(tu)(tu)夾(jia)層(ceng),有(you)明顯的堤(di)(di)身裂縫等。與地質條件直(zhi)接有(you)關的主要為堤(di)(di)基(ji)類隱(yin)患(huan)(huan)(包括(kuo)穿堤(di)(di)建筑(zhu)(zhu)物地基(ji))。例如(ru)上(shang)覆粘性(xing)土(tu)(tu)層(ceng)薄,或本身即(ji)為砂(sha)性(xing)土(tu)(tu)堤(di)(di)基(ji)(包括(kuo)淺(qian)層(ceng)砂(sha)性(xing)土(tu)(tu)透鏡體),存(cun)(cun)在(zai)(zai)滲透破壞的可能性(xing);堤(di)(di)基(ji)有(you)軟弱(ruo)土(tu)(tu)層(ceng)分布(bu),存(cun)(cun)在(zai)(zai)滑動穩定問題(ti)。
常規性隱(yin)患具有直觀性和(he)(he)可檢測性,隱(yin)患的(de)分析(xi)和(he)(he)工程(cheng)處理措(cuo)施(shi)都較為明確,一般情(qing)況下可以(yi)通過(guo)常規性的(de)堤防工程(cheng)維修(xiu)加固予以(yi)消除。
特殊性隱(yin)患(huan):進一步可分為隨機(ji)性隱(yin)患(huan)(堤身或堤基隨機(ji)分布有生物(wu)洞穴、植物(wu)腐爛(lan)物(wu)等)、再(zai)生性隱(yin)患(huan)(生物(wu)洞穴類(lei)隱(yin)患(huan)具有再(zai)生性)、人(ren)類(lei)活動留下的(de)(de)隱(yin)患(huan)(例(li)如(ru)城(cheng)市區與堤外(wai)江河相(xiang)通的(de)(de)早已被廢棄(qi)了的(de)(de)各類(lei)排泄(xie)管道(dao),工程勘探留下的(de)(de)封堵不合格(ge)的(de)(de)鉆孔等)以(yi)及地質(zhi)條件不明的(de)(de)堤基隱(yin)患(huan)等等。
特(te)殊性隱患規律性差,檢測困難,在洪(hong)水期(qi)一旦演變成險情,其突發性質(zhi)增加(jia)了(le)搶險難度。
2.4險情(qing)和隱患與堤型(xing)之間的關系
堤(di)(di)(di)防(fang)(fang)工程的(de)主體~防(fang)(fang)洪(hong)大(da)堤(di)(di)(di),絕(jue)大(da)多數為就地取材填筑的(de)土(tu)堤(di)(di)(di)類型,由于筑堤(di)(di)(di)的(de)歷(li)史條件(jian)、筑堤(di)(di)(di)材料(liao)、自然環境等(deng)等(deng)因素(su)復雜,為后人(ren)留(liu)下(xia)了長(chang)期(qi)隱患(huan),洪(hong)水期(qi)險(xian)情(qing)不斷,令人(ren)心驚。鑒(jian)于土(tu)堤(di)(di)(di)存在的(de)這(zhe)(zhe)些(xie)問(wen)題,近年來(lai)一些(xie)城市(shi)區的(de)堤(di)(di)(di)防(fang)(fang)工程比較(jiao)傾向(xiang)于改土(tu)堤(di)(di)(di)為混(hun)(hun)凝土(tu)防(fang)(fang)洪(hong)墻(堤(di)(di)(di))。混(hun)(hun)凝土(tu)墻可以基(ji)本排除堤(di)(di)(di)身隱患(huan)和險(xian)情(qing),但卻增加了堤(di)(di)(di)基(ji)的(de)出險(xian)負擔(dan)。一是(shi)堤(di)(di)(di)基(ji)的(de)受力(li)條件(jian)發生了較(jiao)大(da)變(bian)化,原(yuan)來(lai)的(de)土(tu)堤(di)(di)(di)是(shi)大(da)面(mian)積分布荷(he)載,混(hun)(hun)凝土(tu)墻改為集(ji)中荷(he)載;二是(shi)堤(di)(di)(di)基(ji)較(jiao)長(chang)滲(shen)徑(jing)變(bian)為水頭集(ji)中的(de)較(jiao)短(duan)滲(shen)徑(jing)。混(hun)(hun)凝土(tu)墻顯然對堤(di)(di)(di)基(ji)地質條件(jian)提出了更高的(de)要求(qiu),這(zhe)(zhe)是(shi)地質工作(zuo)需要重視(shi)的(de)。
另一方面,險情(qing)和(he)(he)隱(yin)患與堤防(fang)(fang)(fang)工(gong)(gong)(gong)程的(de)擋(dang)水(shui)性質在很大關(guan)系(xi)。例如一些(xie)丘陵山區(qu)城市堤防(fang)(fang)(fang)工(gong)(gong)(gong)程,其(qi)擋(dang)水(shui)性質為暴(bao)漲暴(bao)落,遠不能與長(chang)江中(zhong)(zhong)下游堤防(fang)(fang)(fang)工(gong)(gong)(gong)程高水(shui)位較長(chang)時間(jian)(jian)運行(xing)情(qing)況(kuang)相提并論,其(qi)險情(qing)和(he)(he)隱(yin)患的(de)性質也是有(you)差(cha)別(bie)的(de),需要區(qu)別(bie)對(dui)待。而(er)《規范》中(zhong)(zhong)只(zhi)是對(dui)堤防(fang)(fang)(fang)工(gong)(gong)(gong)程的(de)等級標準有(you)所(suo)規定,并沒有(you)對(dui)反(fan)映出險情(qing)和(he)(he)隱(yin)患與等級標準之間(jian)(jian)的(de)關(guan)系(xi),需要由有(you)經驗的(de)地質師(shi)和(he)(he)設(she)計(ji)師(shi)根據具體(ti)情(qing)況(kuang)去理(li)解與把握。
3堤基工程地質分段
3.1堤基工(gong)程地質分段存(cun)在(zai)的問(wen)題(ti)
自(zi)然(ran)界(jie)的(de)地(di)(di)質(zhi)條件千差(cha)萬別。堤(di)(di)防工(gong)程(cheng)(cheng)是(shi)長距離線狀工(gong)程(cheng)(cheng),跨(kua)越(yue)了(le)(le)不(bu)(bu)同的(de)地(di)(di)質(zhi)單元,不(bu)(bu)進行(xing)分(fen)段(duan)分(fen)類區別對(dui)待顯然(ran)是(shi)不(bu)(bu)行(xing)的(de)。堤(di)(di)基工(gong)程(cheng)(cheng)地(di)(di)質(zhi)分(fen)段(duan)又稱堤(di)(di)基工(gong)程(cheng)(cheng)地(di)(di)質(zhi)分(fen)類。在(zai)實際工(gong)程(cheng)(cheng)中,一些勘測設(she)計(ji)單位不(bu)(bu)進行(xing)工(gong)程(cheng)(cheng)地(di)(di)質(zhi)分(fen)段(duan),或(huo)(huo)分(fen)段(duan)不(bu)(bu)合理(li),或(huo)(huo)即便是(shi)進行(xing)了(le)(le)地(di)(di)質(zhi)分(fen)段(duan),但其(qi)巖土(tu)體的(de)物理(li)力學參數(shu)又不(bu)(bu)進行(xing)分(fen)段(duan)統計(ji)分(fen)析,工(gong)程(cheng)(cheng)地(di)(di)質(zhi)條件明(ming)顯不(bu)(bu)同的(de)堤(di)(di)段(duan)沒(mei)有(you)區別開來。還有(you)一些堤(di)(di)基工(gong)程(cheng)(cheng)地(di)(di)質(zhi)分(fen)段(duan)的(de)結果不(bu)(bu)同程(cheng)(cheng)度地(di)(di)存在(zai)自(zi)相矛盾(dun)性,對(dui)工(gong)程(cheng)(cheng)設(she)計(ji)和工(gong)程(cheng)(cheng)措施的(de)選定缺乏針對(dui)性。當然(ran),更多的(de)情況是(shi)工(gong)程(cheng)(cheng)地(di)(di)質(zhi)分(fen)段(duan)的(de)合理(li)性與(yu)科學性不(bu)(bu)足。
例(li)如(ru)某設計(ji)院參加過(guo)大量堤(di)(di)(di)(di)(di)防工(gong)(gong)程(cheng)(cheng)地(di)(di)質(zhi)(zhi)(zhi)勘(kan)察,有(you)(you)豐富的(de)(de)堤(di)(di)(di)(di)(di)防工(gong)(gong)程(cheng)(cheng)地(di)(di)質(zhi)(zhi)(zhi)勘(kan)察經驗(yan),他們進行(xing)堤(di)(di)(di)(di)(di)基工(gong)(gong)程(cheng)(cheng)地(di)(di)質(zhi)(zhi)(zhi)分(fen)段所(suo)考(kao)慮的(de)(de)因素(su)有(you)(you):上覆粘(zhan)性土層的(de)(de)厚度、外灘(tan)寬度和(he)歷史險(xian)情(qing)等,將(jiang)堤(di)(di)(di)(di)(di)基分(fen)為(wei)工(gong)(gong)程(cheng)(cheng)地(di)(di)質(zhi)(zhi)(zhi)條件好、較(jiao)好、較(jiao)差(cha)和(he)差(cha)四個等級。如(ru)此(ci)分(fen)段其大原則(ze)沒有(you)(you)什么問題(ti),但對于一些特(te)殊(shu)組合(he)則(ze)不(bu)易明確。例(li)如(ru),某堤(di)(di)(di)(di)(di)基段其上覆粘(zhan)性土層足夠(gou)厚,堤(di)(di)(di)(di)(di)內(nei)也沒有(you)(you)任何(he)險(xian)情(qing),但堤(di)(di)(di)(di)(di)外無灘(tan),受水流(liu)(liu)沖刷(shua)崩(beng)(beng)(beng)岸嚴重,是(shi)典型的(de)(de)險(xian)工(gong)(gong)險(xian)段。將(jiang)這種(zhong)堤(di)(di)(di)(di)(di)段分(fen)成(cheng)工(gong)(gong)程(cheng)(cheng)地(di)(di)質(zhi)(zhi)(zhi)條件差(cha)或(huo)較(jiao)差(cha)都(dou)不(bu)一定合(he)適。因為(wei)出現的(de)(de)險(xian)情(qing)不(bu)是(shi)堤(di)(di)(di)(di)(di)基本身的(de)(de)工(gong)(gong)程(cheng)(cheng)地(di)(di)質(zhi)(zhi)(zhi)條件差(cha),而是(shi)堤(di)(di)(di)(di)(di)外腳受水流(liu)(liu)沖刷(shua)產生的(de)(de)崩(beng)(beng)(beng)塌或(huo)塌滑,且在(zai)不(bu)同水位(wei)條件下其險(xian)情(qing)不(bu)同,與(yu)江河(he)水流(liu)(liu)及河(he)勢變化(hua)都(dou)有(you)(you)關系。顯然(ran),崩(beng)(beng)(beng)岸類(lei)險(xian)工(gong)(gong)險(xian)段在(zai)堤(di)(di)(di)(di)(di)基工(gong)(gong)程(cheng)(cheng)地(di)(di)質(zhi)(zhi)(zhi)分(fen)段時應結合(he)河(he)勢水流(liu)(liu)特(te)征單(dan)獨進行(xing)分(fen)類(lei),以便于有(you)(you)針對性考(kao)慮工(gong)(gong)程(cheng)(cheng)處理措(cuo)施。例(li)如(ru)對某一類(lei)崩(beng)(beng)(beng)岸問題(ti),拋石護腳是(shi)有(you)(you)效的(de)(de),而另(ling)一類(lei)崩(beng)(beng)(beng)岸問題(ti)或(huo)許(xu)要與(yu)“丁(ding)壩”挑流(liu)(liu)改(gai)變流(liu)(liu)態相結合(he)才能從根本上解決問題(ti),或(huo)者無建“丁(ding)堤(di)(di)(di)(di)(di)”的(de)(de)條件,則(ze)需(xu)考(kao)慮“樁”、“籠”等工(gong)(gong)程(cheng)(cheng)措(cuo)施。
另一方面,對于堤(di)基工(gong)程地質(zhi)(zhi)(zhi)條(tiao)件(jian)(jian)用“好”與“差(cha)”來(lai)評(ping)價(jia),其針對性(xing)不強。例如(ru),存(cun)在(zai)滲透(tou)破壞(huai)的(de)(de)(de)堤(di)基劃為(wei)工(gong)程地質(zhi)(zhi)(zhi)條(tiao)件(jian)(jian)差(cha),而實際上可能此類堤(di)基的(de)(de)(de)承載能力和抗滑穩定(ding)(ding)性(xing)都是很好的(de)(de)(de),如(ru)砂性(xing)土(tu)堤(di)基。又如(ru)淤泥質(zhi)(zhi)(zhi)土(tu)類堤(di)基,其承載能力和抗滑穩定(ding)(ding)性(xing)差(cha)些,但(dan)滲透(tou)系數卻很小,抗滲條(tiao)件(jian)(jian)是好的(de)(de)(de)。如(ru)此等(deng)等(deng),用常規的(de)(de)(de)工(gong)程地質(zhi)(zhi)(zhi)條(tiao)件(jian)(jian)好或差(cha)來(lai)評(ping)價(jia),都存(cun)在(zai)明顯(xian)的(de)(de)(de)矛盾。
目前各(ge)勘測單位(wei)自行制定的堤(di)基工(gong)(gong)程地(di)質(zhi)分(fen)段原(yuan)則(ze),基本上是以工(gong)(gong)程地(di)質(zhi)條件為基礎,再考慮(lv)一些自然(ran)因(yin)素和工(gong)(gong)程因(yin)素,筆者認(ren)為這種分(fen)段法的思路(lu)源自于常規(gui)的工(gong)(gong)程地(di)質(zhi)分(fen)類(lei)法,跳不出(chu)傳統(tong)思維的約束,不能較好(hao)地(di)適應堤(di)防工(gong)(gong)程的實際,需(xu)要探索(suo)新路(lu)。
3.2堤基工程地(di)質分段
我們在(zai)進行傳統意(yi)義上的(de)工(gong)(gong)程(cheng)地(di)(di)質(zhi)評價(jia)時,通(tong)常從工(gong)(gong)程(cheng)地(di)(di)質(zhi)條件出(chu)發,結(jie)合(he)工(gong)(gong)程(cheng)建筑物特點(dian),界定出(chu)主(zhu)要工(gong)(gong)程(cheng)地(di)(di)質(zhi)問(wen)題。在(zai)堤(di)基(ji)工(gong)(gong)程(cheng)地(di)(di)質(zhi)分(fen)段(duan)(duan)中,我們不妨(fang)借用逆向(xiang)思維的(de)思想(xiang),以(yi)(yi)工(gong)(gong)程(cheng)地(di)(di)質(zhi)問(wen)題為主(zhu)線,以(yi)(yi)工(gong)(gong)程(cheng)地(di)(di)質(zhi)條件為基(ji)礎,再結(jie)合(he)歷史險情(qing)類(lei)型,爭(zheng)取探討出(chu)一個符(fu)合(he)工(gong)(gong)程(cheng)實際的(de)堤(di)基(ji)工(gong)(gong)程(cheng)地(di)(di)質(zhi)分(fen)段(duan)(duan)法。
本文(wen)強調(diao)的是(shi)“工(gong)程地(di)質(zhi)(zhi)”分段,因此主(zhu)(zhu)要(yao)是(shi)對堤(di)(di)基(ji)(ji)而言的。我們知(zhi)道,無論堤(di)(di)基(ji)(ji)地(di)質(zhi)(zhi)條(tiao)件有多復雜,其主(zhu)(zhu)要(yao)工(gong)程地(di)質(zhi)(zhi)問(wen)(wen)題則是(shi)明確的,歸(gui)納起來主(zhu)(zhu)要(yao)為三(san)類(即三(san)大主(zhu)(zhu)要(yao)工(gong)程地(di)質(zhi)(zhi)問(wen)(wen)題):崩岸(an)、滲透(tou)破壞、滑(hua)動(dong)與(yu)沉降變形(xing)。絕大多數堤(di)(di)基(ji)(ji)巖土(tu)體(ti)不外乎為:砂(sha)性(xing)土(tu)、粘性(xing)土(tu)和砂(sha)性(xing)土(tu)與(yu)粘性(xing)土(tu)的混合結構;城(cheng)市區雜填土(tu)較為復雜,另當別論。
根據以(yi)上以(yi)工程(cheng)地(di)質問題(ti)(ti)(ti)為主(zhu)線的(de)(de)分(fen)段原則,我們首先將(jiang)堤(di)基分(fen)為三(san)大類:Ⅰ類(不存(cun)在問題(ti)(ti)(ti)的(de)(de)堤(di)基)、Ⅱ類(可能存(cun)在問題(ti)(ti)(ti)的(de)(de)堤(di)基)和(he)Ⅲ類(存(cun)在問題(ti)(ti)(ti)的(de)(de)堤(di)基)。對于(yu)Ⅱ類和(he)Ⅲ類堤(di)基,按其(qi)存(cun)在問題(ti)(ti)(ti)的(de)(de)性質可繼續劃分(fen)亞類。
(1)Ⅲ類(lei)(存在問題的堤(di)基)
堤(di)基發生過歷史險情(qing),尤(you)其(qi)是一些每年汛期都要(yao)(yao)出險的(de)部位,在汛期要(yao)(yao)投入大量的(de)人力(li)(li)物力(li)(li)搶(qiang)險才能保證大堤(di)安全(quan)的(de)堤(di)段。按出除性(xing)質又分為(wei)兩個(ge)亞類:Ⅲ-1和Ⅲ-2類。
Ⅲ-1類:主要指崩岸(an)類,這是在堤(di)基分段(duan)時對(dui)有問題的堤(di)基段(duan)應首先分出來的一類。
Ⅲ-2類(lei):除崩岸之外的一切堤基存在問(wen)題的堤段。按工程地質問(wen)題繼續(xu)分出兩個(ge)子(zi)類(lei):
Ⅲ-2-1類:存在滲透破(po)壞(huai)的(de)堤(di)基(ji)(ji)段。汛(xun)期出現過冒砂、涌混水等險情;堤(di)基(ji)(ji)為砂性土,或表層粘性土較薄,或淺層有砂性土透境(jing)體分布,或堤(di)身與堤(di)基(ji)(ji)接觸部位存在滲漏破(po)壞(huai)問題(ti)。
Ⅲ-2-2類(lei):存在滑(hua)動(dong)與(yu)沉(chen)降變(bian)形(xing)的堤(di)(di)基(ji)(ji)(ji)段。運行(xing)期(qi)或(huo)施(shi)工(gong)期(qi)發生過堤(di)(di)基(ji)(ji)(ji)土層(ceng)滑(hua)動(dong),或(huo)沉(chen)降過大(da)導(dao)致(zhi)堤(di)(di)身開裂;堤(di)(di)基(ji)(ji)(ji)有(you)壓縮性大(da)、承載力和抗(kang)剪強度低的軟弱(ruo)土層(ceng)分(fen)布,或(huo)堤(di)(di)基(ji)(ji)(ji)清(qing)基(ji)(ji)(ji)不徹(che)底,導(dao)致(zhi)堤(di)(di)身與(yu)堤(di)(di)基(ji)(ji)(ji)接觸面存在滑(hua)動(dong)軟弱(ruo)帶(dai)。
(2)Ⅱ類(可能(neng)存在問題的堤基段)
此類與前(qian)述的堤(di)基隱患(huan)相對應。在汛(xun)期有一定(ding)滲水(shui)情況(kuang)發生,但并(bing)未發展(zhan)成(cheng)為險情;或(huo)經(jing)地(di)質(zhi)勘(kan)察,地(di)基中存在砂性土透鏡體、軟(ruan)弱(ruo)夾層等(deng)不利地(di)質(zhi)條件,經(jing)滲控或(huo)穩定(ding)性驗(yan)算,安全系數(shu)達不到規范要求的堤(di)基;或(huo)存在生物(wu)洞穴等(deng)其它隱患(huan)的堤(di)基。
(3)Ⅰ類(不(bu)存在問題堤基段)
歷(li)史上無險情(qing)發(fa)生(sheng),堤基為厚度(du)較(jiao)大的粘性(xing)土或基巖,物性(xing)指標和力學指標均(jun)較(jiao)好,不存在三大主要工程(cheng)地質(zhi)問題。
(4)結合工程實際(ji)進一步細分亞類的原則
以(yi)上分(fen)類法(fa),從宏觀(guan)上將堤(di)基(ji)分(fen)為三(san)大(da)類別,但(dan)在(zai)具體實(shi)(shi)施過程(cheng)(cheng)(cheng)中,還可以(yi)根(gen)據工程(cheng)(cheng)(cheng)實(shi)(shi)際(ji)按不同工程(cheng)(cheng)(cheng)地質(zhi)條(tiao)件和(he)工程(cheng)(cheng)(cheng)地質(zhi)問題進一(yi)步(bu)細化(hua)。例如,對(dui)于Ⅱ類堤(di)基(ji)段,可以(yi)按可能存(cun)在(zai)問題的(de)性(xing)(xing)質(zhi)進一(yi)步(bu)細化(hua);對(dui)于Ⅲ類堤(di)基(ji)段,也可以(yi)按存(cun)在(zai)問題的(de)嚴(yan)重程(cheng)(cheng)(cheng)度或巖土體的(de)性(xing)(xing)質(zhi)等進一(yi)步(bu)細化(hua)。堤(di)基(ji)分(fen)段的(de)科學性(xing)(xing)、合理性(xing)(xing)、實(shi)(shi)用性(xing)(xing)和(he)可操作(zuo)性(xing)(xing),不但(dan)是地質(zhi)師對(dui)堤(di)防工程(cheng)(cheng)(cheng)理解(jie)程(cheng)(cheng)(cheng)度的(de)反映,更是一(yi)項創(chuang)造性(xing)(xing)的(de)工作(zuo)。本文所提(ti)出的(de)分(fen)段原則和(he)方法(fa),尚有(you)待工程(cheng)(cheng)(cheng)實(shi)(shi)踐去檢驗。
3.3堤基(ji)工程地質分(fen)段對勘測(ce)設計(ji)工作的指導作用(yong)
在(zai)進(jin)行工程地(di)質勘察(cha)時,Ⅲ類是重(zhong)點(dian),應(ying)根據具體情況(kuang)加(jia)密(mi)勘探(tan)(tan)點(dian);Ⅱ類次之,實施(shi)常規性(xing)勘探(tan)(tan)即可(ke)(ke);Ⅰ類基本上可(ke)(ke)以(yi)不(bu)考慮地(di)質勘察(cha)。設計方面(mian),Ⅲ類堤(di)基必須考慮工程措施(shi);Ⅱ類堤(di)基應(ying)視具體情況(kuang)而定,也(ye)可(ke)(ke)以(yi)通過進(jin)一步(bu)勘探(tan)(tan)和檢測或(huo)監測結果來確定工程措施(shi);Ⅰ類堤(di)基則不(bu)需要采取工程措施(shi),僅(jin)僅(jin)通過堤(di)防工程的常規性(xing)維護即可(ke)(ke)。
4執行《堤防工程(cheng)地(di)質勘察規程(cheng)》的基本(ben)原則
從(cong)《堤防工程地(di)質(zhi)勘察(cha)規(gui)程》頒(ban)布實施三年(nian)多(duo)來的(de)(de)(de)(de)實踐(jian)可(ke)以看到,除了(le)《規(gui)程》本(ben)身存在一些尚需修訂的(de)(de)(de)(de)問題(ti)之外,能夠將《規(gui)程》與(yu)(yu)工程實際(ji)相結合,創造性地(di)執行和應用《規(gui)程》,準確地(di)把握《規(gui)程》的(de)(de)(de)(de)原則(ze)性與(yu)(yu)靈(ling)活性,是(shi)對地(di)質(zhi)師綜合素質(zhi)的(de)(de)(de)(de)高(gao)標準要求。業(ye)務能力和創新意識,是(shi)檢驗和考察(cha)我們對堤防工程的(de)(de)(de)(de)認識深(shen)度與(yu)(yu)理(li)解能力。筆者的(de)(de)(de)(de)理(li)解主要反映在以下(xia)幾個方面。
4.1勘測階段
已(yi)建堤(di)(di)防除險加固工(gong)程(cheng)(cheng)可以(yi)一次(ci)進場(chang),達到(dao)初(chu)設深度;新建堤(di)(di)防可按(an)可研和(he)初(chu)設兩個階段(duan)進行(xing)。其理由是:新建堤(di)(di)防存在(zai)線路比(bi)(bi)選(xuan)問題,不(bu)(bu)可能將比(bi)(bi)選(xuan)堤(di)(di)線的工(gong)程(cheng)(cheng)地質(zhi)條件(jian)都按(an)初(chu)設要求做到(dao)相(xiang)同深度;已(yi)建堤(di)(di)防一般不(bu)(bu)存在(zai)線路比(bi)(bi)選(xuan)問題,因此也就不(bu)(bu)存在(zai)多階段(duan)多方案的反(fan)復比(bi)(bi)選(xuan)問題。另外,新建堤(di)(di)防工(gong)程(cheng)(cheng)應(ying)該在(zai)規劃階段(duan)即開展(zhan)工(gong)程(cheng)(cheng)地質(zhi)工(gong)作,以(yi)便將規劃線路從(cong)地質(zhi)專業的角度先(xian)期界定其可行(xing)性(xing)。
4.2勘(kan)測深度及勘(kan)探工作量(liang)
在實(shi)際(ji)工(gong)作(zuo)(zuo)(zuo)中(zhong),對于堤防工(gong)程(cheng)(cheng)勘(kan)(kan)測(ce)深度與勘(kan)(kan)探(tan)(tan)工(gong)作(zuo)(zuo)(zuo)量(liang)問(wen)(wen)題,在理(li)解和(he)把握上(shang)有(you)較(jiao)大(da)差異。有(you)人喜歡嚴(yan)格按(an)《規(gui)程(cheng)(cheng)》要(yao)求布置(zhi)(zhi)勘(kan)(kan)探(tan)(tan)工(gong)作(zuo)(zuo)(zuo)量(liang),而少在工(gong)程(cheng)(cheng)地(di)(di)(di)質條件(jian)的(de)(de)(de)查明與工(gong)程(cheng)(cheng)地(di)(di)(di)質問(wen)(wen)題的(de)(de)(de)分(fen)析方面下(xia)功夫。筆者強烈主張,一(yi)是(shi)(shi)將安全正常運行(xing)的(de)(de)(de)堤段與險工(gong)險段區別開來(lai),二是(shi)(shi)將堤身出險情(qing)況與堤基出險情(qing)況區別開來(lai),分(fen)別對待。這(zhe)也是(shi)(shi)本文(wen)費了較(jiao)多筆墨進行(xing)險情(qing)隱(yin)患(huan)分(fen)類和(he)堤基工(gong)程(cheng)(cheng)地(di)(di)(di)質分(fen)段的(de)(de)(de)目的(de)(de)(de)之一(yi)。特別是(shi)(shi)經歷(li)了98特大(da)洪水考驗過的(de)(de)(de)堤防工(gong)程(cheng)(cheng),未出險的(de)(de)(de)堤段完(wan)全沒(mei)有(you)必要(yao)“嚴(yan)格”按(an)照(zhao)(zhao)《規(gui)程(cheng)(cheng)》要(yao)求的(de)(de)(de)勘(kan)(kan)探(tan)(tan)工(gong)作(zuo)(zuo)(zuo)量(liang)去實(shi)施(shi)地(di)(di)(di)質勘(kan)(kan)探(tan)(tan),即(ji)使按(an)照(zhao)(zhao)《規(gui)程(cheng)(cheng)》中(zhong)的(de)(de)(de)上(shang)限要(yao)求,也是(shi)(shi)一(yi)種(zhong)毫無意(yi)義的(de)(de)(de)巨大(da)浪費。而應在分(fen)析險工(gong)險段的(de)(de)(de)具體問(wen)(wen)題之基礎上(shang)明確(que)勘(kan)(kan)察目的(de)(de)(de),研究和(he)選(xuan)擇勘(kan)(kan)探(tan)(tan)方法(fa),合理(li)布置(zhi)(zhi)勘(kan)(kan)探(tan)(tan)工(gong)作(zuo)(zuo)(zuo)量(liang),重(zhong)點在工(gong)程(cheng)(cheng)地(di)(di)(di)質問(wen)(wen)題的(de)(de)(de)分(fen)析上(shang)下(xia)功夫。如(ru)果認可本文(wen)提出的(de)(de)(de)堤基分(fen)段原則和(he)方法(fa),地(di)(di)(di)質勘(kan)(kan)探(tan)(tan)工(gong)作(zuo)(zuo)(zuo)的(de)(de)(de)布置(zhi)(zhi)則更(geng)為方向明確(que)目標清(qing)楚。
4.3《規程(cheng)》原則(ze)性與(yu)靈活(huo)性的準(zhun)確把握
《規(gui)(gui)(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)》的(de)(de)原(yuan)則(ze)性(xing)(xing)和(he)嚴肅性(xing)(xing)是(shi)(shi)(shi)不可(ke)置疑的(de)(de),這并不等(deng)(deng)于(yu)(yu)“死”規(gui)(gui)(gui)(gui)(gui)(gui)定。明(ming)顯與(yu)工(gong)(gong)程(cheng)(cheng)(cheng)實際不相(xiang)符合的(de)(de)具體問題,需(xu)(xu)要由(you)地質(zhi)(zhi)師的(de)(de)創造(zao)性(xing)(xing)勞動(dong)加以“靈活(huo)”處理。規(gui)(gui)(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)規(gui)(gui)(gui)(gui)(gui)(gui)范是(shi)(shi)(shi)指導技術工(gong)(gong)作(zuo)(zuo)的(de)(de)法規(gui)(gui)(gui)(gui)(gui)(gui)性(xing)(xing)文(wen)件,并不等(deng)(deng)同于(yu)(yu)為犯(fan)罪(zui)分子(zi)定罪(zui)的(de)(de)法律(lv)(lv)條款,因(yin)此執行(xing)規(gui)(gui)(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)規(gui)(gui)(gui)(gui)(gui)(gui)范是(shi)(shi)(shi)可(ke)以有“靈活(huo)”性(xing)(xing)的(de)(de)。靈活(huo)性(xing)(xing)的(de)(de)把(ba)握原(yuan)則(ze)是(shi)(shi)(shi):不應因(yin)忠(zhong)實嚴格(ge)執行(xing)規(gui)(gui)(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)規(gui)(gui)(gui)(gui)(gui)(gui)范而遺(yi)漏(lou)重大工(gong)(gong)程(cheng)(cheng)(cheng)地質(zhi)(zhi)問題,留下工(gong)(gong)程(cheng)(cheng)(cheng)隱患造(zao)成工(gong)(gong)程(cheng)(cheng)(cheng)事(shi)故;也不應造(zao)成不必(bi)要的(de)(de)浪費。例(li)如,對(dui)(dui)于(yu)(yu)某些特殊的(de)(de)險工(gong)(gong)險段、Ⅲ類堤基(ji)、城市區(qu)規(gui)(gui)(gui)(gui)(gui)(gui)律(lv)(lv)性(xing)(xing)差的(de)(de)雜填土和(he)人類活(huo)動(dong)留下的(de)(de)隱患管(guan)道等(deng)(deng),《規(gui)(gui)(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)》規(gui)(gui)(gui)(gui)(gui)(gui)定的(de)(de)勘探工(gong)(gong)作(zuo)(zuo)量可(ke)能就(jiu)不能滿足要求;而對(dui)(dui)于(yu)(yu)安全正常運行(xing)多年的(de)(de)Ⅰ類堤基(ji),按《規(gui)(gui)(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)》規(gui)(gui)(gui)(gui)(gui)(gui)定的(de)(de)勘探工(gong)(gong)作(zuo)(zuo)量又(you)顯得沒(mei)有必(bi)要。總之(zhi),準(zhun)確把(ba)握執行(xing)規(gui)(gui)(gui)(gui)(gui)(gui)程(cheng)(cheng)(cheng)規(gui)(gui)(gui)(gui)(gui)(gui)范的(de)(de)原(yuan)則(ze)性(xing)(xing)與(yu)靈活(huo)性(xing)(xing),需(xu)(xu)要地質(zhi)(zhi)師的(de)(de)責任心、業(ye)務(wu)水平和(he)創新意(yi)識,同時(shi)也體現出了工(gong)(gong)程(cheng)(cheng)(cheng)地質(zhi)(zhi)專業(ye)的(de)(de)特殊性(xing)(xing)與(yu)復雜性(xing)(xing)。
5不同(tong)行業標(biao)準之間的關系(xi)
堤(di)防(fang)工(gong)(gong)程(cheng)(cheng)(cheng)地(di)基(ji)(ji)多為(wei)土(tu)(tu)質地(di)基(ji)(ji),其工(gong)(gong)程(cheng)(cheng)(cheng)地(di)質評價(jia)的(de)(de)(de)基(ji)(ji)本理(li)論依據(ju)是(shi)(shi)土(tu)(tu)力(li)學,因(yin)而容易與工(gong)(gong)民建(jian)(jian)基(ji)(ji)礎設(she)計相(xiang)混淆。目前反映比(bi)較(jiao)集中的(de)(de)(de)是(shi)(shi)執行(xing)水(shui)利行(xing)業標準還是(shi)(shi)執行(xing)以(yi)工(gong)(gong)民建(jian)(jian)為(wei)主要(yao)對(dui)象的(de)(de)(de)《巖土(tu)(tu)工(gong)(gong)程(cheng)(cheng)(cheng)勘察(cha)(cha)規(gui)范(fan)》(國(guo)家標準GB50021—94簡(jian)稱《巖土(tu)(tu)規(gui)范(fan)》)。兩(liang)個標準既(ji)有共同之處,又有一(yi)定(ding)的(de)(de)(de)差異(yi)。我們認為(wei)應該以(yi)水(shui)利行(xing)業標準為(wei)主要(yao)依據(ju),同時(shi)參照《巖土(tu)(tu)規(gui)范(fan)》。原因(yin)是(shi)(shi):①《巖土(tu)(tu)規(gui)范(fan)》主要(yao)是(shi)(shi)針對(dui)一(yi)般性工(gong)(gong)民建(jian)(jian)地(di)基(ji)(ji)勘察(cha)(cha)與評價(jia),而水(shui)工(gong)(gong)建(jian)(jian)筑(zhu)物與工(gong)(gong)民建(jian)(jian)有根(gen)(gen)本性的(de)(de)(de)區別,前者(zhe)(zhe)地(di)基(ji)(ji)所承受的(de)(de)(de)荷載(zai)以(yi)垂直向(xiang)為(wei)主,建(jian)(jian)筑(zhu)物對(dui)地(di)基(ji)(ji)的(de)(de)(de)要(yao)求主要(yao)反映在承載(zai)力(li);后者(zhe)(zhe)的(de)(de)(de)荷載(zai)是(shi)(shi)垂向(xiang)與水(shui)平(ping)向(xiang)的(de)(de)(de)組合,地(di)基(ji)(ji)巖土(tu)(tu)體(ti)處于復雜應力(li)狀態,特別是(shi)(shi)水(shui)荷載(zai)對(dui)地(di)基(ji)(ji)巖土(tu)(tu)體(ti)的(de)(de)(de)復雜作(zuo)用(yong),是(shi)(shi)水(shui)工(gong)(gong)建(jian)(jian)筑(zhu)物與工(gong)(gong)民建(jian)(jian)的(de)(de)(de)根(gen)(gen)本區別。②《巖土(tu)(tu)規(gui)范(fan)》在總則(ze)中表示該規(gui)范(fan)適用(yong)于除水(shui)利工(gong)(gong)程(cheng)(cheng)(cheng)、……以(yi)外的(de)(de)(de)工(gong)(gong)程(cheng)(cheng)(cheng)建(jian)(jian)設(she)巖土(tu)(tu)工(gong)(gong)程(cheng)(cheng)(cheng)勘察(cha)(cha)。明(ming)確了不適用(yong)于水(shui)利工(gong)(gong)程(cheng)(cheng)(cheng)。③《巖土(tu)(tu)規(gui)范(fan)》中對(dui)勘探(tan)量的(de)(de)(de)安排和勘探(tan)工(gong)(gong)作(zuo)的(de)(de)(de)布置主要(yao)依照巖土(tu)(tu)工(gong)(gong)程(cheng)(cheng)(cheng)勘察(cha)(cha)等級(ji)來(lai)制定(ding),而堤(di)防(fang)工(gong)(gong)程(cheng)(cheng)(cheng)則(ze)主要(yao)從工(gong)(gong)程(cheng)(cheng)(cheng)勘測設(she)計的(de)(de)(de)階(jie)段來(lai)確定(ding)。
關(guan)于土(tu)(tu)(tu)的(de)(de)(de)(de)(de)分(fen)(fen)類(lei)(lei)問題,也(ye)(ye)是近年(nian)來較為混亂的(de)(de)(de)(de)(de)問題之一(yi)。1990年(nian)以(yi)(yi)前,土(tu)(tu)(tu)的(de)(de)(de)(de)(de)分(fen)(fen)類(lei)(lei)主(zhu)要以(yi)(yi)1962年(nian)版(ban)的(de)(de)(de)(de)(de)《土(tu)(tu)(tu)工試驗(yan)操作(zuo)規(gui)程》為依據,采用(yong)(yong)土(tu)(tu)(tu)的(de)(de)(de)(de)(de)分(fen)(fen)類(lei)(lei)三角(jiao)坐標(biao)(biao),這種分(fen)(fen)類(lei)(lei)法(fa)以(yi)(yi)顆分(fen)(fen)為基礎(chu),以(yi)(yi)礫石、砂粒(li)和細粒(li)的(de)(de)(de)(de)(de)含量百分(fen)(fen)比來給細粒(li)土(tu)(tu)(tu)定名。廣大設計院應用(yong)(yong)這種分(fen)(fen)類(lei)(lei)方(fang)法(fa)比較成(cheng)熟。1991年(nian)國標(biao)(biao)《土(tu)(tu)(tu)的(de)(de)(de)(de)(de)分(fen)(fen)類(lei)(lei)標(biao)(biao)準(zhun)》(GBJ145-90)頒布(bu),此(ci)標(biao)(biao)準(zhun)以(yi)(yi)顆分(fen)(fen)為基礎(chu),以(yi)(yi)塑(su)性指數和液限為控制指標(biao)(biao)對(dui)土(tu)(tu)(tu)進行(xing)分(fen)(fen)類(lei)(lei),1999年(nian)頒布(bu)的(de)(de)(de)(de)(de)水(shui)利行(xing)業標(biao)(biao)準(zhun)《土(tu)(tu)(tu)工試驗(yan)規(gui)程》對(dui)土(tu)(tu)(tu)的(de)(de)(de)(de)(de)分(fen)(fen)類(lei)(lei)也(ye)(ye)沿用(yong)(yong)此(ci)國標(biao)(biao)。我(wo)們(men)認為,目前兩種分(fen)(fen)類(lei)(lei)都有各自(zi)的(de)(de)(de)(de)(de)特點,原則上應使(shi)用(yong)(yong)國標(biao)(biao)和最(zui)新的(de)(de)(de)(de)(de)行(xing)業標(biao)(biao)準(zhun)為主(zhu),現階段也(ye)(ye)可以(yi)(yi)根(gen)據各單位對(dui)標(biao)(biao)準(zhun)的(de)(de)(de)(de)(de)理解和與工程相結合的(de)(de)(de)(de)(de)具體(ti)情(qing)況,互相參(can)照使(shi)用(yong)(yong),只要能夠客觀(guan)地反映工程實(shi)際(ji),滿足為工程設計提(ti)供有關(guan)地質(zhi)參(can)數的(de)(de)(de)(de)(de)要求即可。另(ling)一(yi)方(fang)面,我(wo)們(men)也(ye)(ye)提(ti)倡和鼓勵對(dui)此(ci)類(lei)(lei)問題深(shen)入探(tan)討,為進一(yi)步(bu)統一(yi)標(biao)(biao)準(zhun)進行(xing)實(shi)踐和理論(lun)準(zhun)備。
6堤防工(gong)程地質勘察的成(cheng)果(guo)資料
堤防工程地質勘察所獲得的基礎性資料數據,具有種類繁多數量巨大的特點。這些資料數據的分析整理歸納匯總,要求標準化,計算機化,最后形成能夠通過計算機綜合管理的(de)(de)(de)數(shu)字(zi)化的(de)(de)(de)基(ji)礎(chu)資(zi)料數(shu)據(ju)庫(ku)(ku)系統(tong)(tong)(tong),并與堤(di)防(fang)工(gong)程的(de)(de)(de)其它資(zi)料數(shu)據(ju)庫(ku)(ku)系統(tong)(tong)(tong)集(ji)(ji)成(cheng),充(chong)分(fen)應用計算機網絡技(ji)術,為(wei)堤(di)防(fang)工(gong)程建設、管理和抗(kang)洪(hong)搶(qiang)(qiang)險(xian)提(ti)供(gong)使(shi)用方(fang)便功能(neng)強大(da)的(de)(de)(de)檢索查詢(xun)指揮(hui)調(diao)度(du)系統(tong)(tong)(tong)。集(ji)(ji)成(cheng)后的(de)(de)(de)系統(tong)(tong)(tong)可(ke)在局域(yu)網、城域(yu)網、廣域(yu)網和Internet/Intranet上(shang)運行。系統(tong)(tong)(tong)要求具有靈活的(de)(de)(de)結構(gou)定(ding)義、多種存(cun)儲方(fang)式、強大(da)方(fang)便的(de)(de)(de)查詢(xun)定(ding)位功能(neng)、豐富的(de)(de)(de)統(tong)(tong)(tong)計報表(biao)功能(neng)以及(ji)可(ke)靠(kao)的(de)(de)(de)數(shu)據(ju)安全(quan)保(bao)證體系等;能(neng)夠通過圖示圖表(biao)提(ti)供(gong)隱患預測、險(xian)情分(fen)析(xi)、搶(qiang)(qiang)險(xian)提(ti)示、決策支持、模擬(ni)潰(kui)堤(di)和決口后洪(hong)水進堤(di)的(de)(de)(de)演變趨勢。目前的(de)(de)(de)基(ji)礎(chu)性工(gong)作(zuo)是(shi)制定(ding)目標,統(tong)(tong)(tong)一規(gui)劃(hua),結構(gou)設計,系統(tong)(tong)(tong)集(ji)(ji)成(cheng)。
堤防工程數據庫(ku)系(xi)統(tong)需要列為專題研(yan)究(jiu),力爭全國統(tong)一,至少也應該(gai)全流域統(tong)一。各類資料數據的使用權限、歸檔管理、存儲格式和(he)形式、存儲介質(zhi)等等,都應該(gai)及早研(yan)究(jiu),統(tong)一規(gui)定。
7結語
98特(te)大洪水期間,抗洪搶險(xian)場面之驚(jing)心(xin)動魄,至今仍然令人(ren)難以忘懷(huai)。大洪水給人(ren)以大啟示。中(zhong)國歷(li)(li)史(shi)上前所未(wei)有(you)的(de)(de)(de)大規模堤防工(gong)(gong)程(cheng)(cheng)建(jian)設(she)在98特(te)大洪水之后迅(xun)速(su)拉開(kai)序幕。經(jing)歷(li)(li)了98特(te)大洪水洗禮(li)過的(de)(de)(de)江河(he)堤防工(gong)(gong)程(cheng)(cheng),其工(gong)(gong)程(cheng)(cheng)隱患(huan)基本暴(bao)露(lu)無遺,認真研究(jiu)堤防工(gong)(gong)程(cheng)(cheng)的(de)(de)(de)出(chu)險(xian)機理,總結未(wei)出(chu)險(xian)工(gong)(gong)程(cheng)(cheng)的(de)(de)(de)成功范例,吸取前人(ren)修建(jian)堤防工(gong)(gong)程(cheng)(cheng)的(de)(de)(de)歷(li)(li)史(shi)經(jing)驗,做好堤防工(gong)(gong)程(cheng)(cheng)的(de)(de)(de)勘測設(she)計(ji)工(gong)(gong)作,是肩負著堤防工(gong)(gong)程(cheng)(cheng)建(jian)設(she)的(de)(de)(de)各(ge)級領導和工(gong)(gong)程(cheng)(cheng)技術人(ren)員的(de)(de)(de)神圣(sheng)職(zhi)責。
近(jin)幾年(nian)來我們(men)參(can)加(jia)了(le)大量(liang)堤防工程審查,在向生產(chan)第一(yi)線的(de)(de)廣(guang)大工程技(ji)術干部學習的(de)(de)同時,也對堤防工程地質(zhi)勘(kan)察中普遍存在的(de)(de)一(yi)些問題(ti)進行(xing)了(le)認真思考。本文對于執(zhi)行(xing)《規程》的(de)(de)原(yuan)則(ze)、勘(kan)探(tan)工作量(liang)的(de)(de)控(kong)制、勘(kan)測資料的(de)(de)整理(li)等等問題(ti)表明了(le)我們(men)的(de)(de)觀(guan)點;關于堤防工程險情和隱患分類,我們(men)認為是(shi)實踐上升到理(li)論(lun)(lun)的(de)(de)必然(ran)過程;關于堤基分段分類的(de)(de)原(yuan)則(ze)與方法,屬于工程地質(zhi)理(li)論(lun)(lun)與實踐相結合的(de)(de)探(tan)討性(xing)課題(ti),同時又是(shi)指導工程勘(kan)測設計的(de)(de)基礎性(xing)工作。
本文觀點供同行們(men)參考,愿(yuan)與大家共同討論(lun)。
參考文獻:
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