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1、 調(diào)查的非液化層的厚度表面液化引起的原因g.papathanassiou地質(zhì)系，薩洛尼卡亞里士多德大學(xué)，希臘摘要：這項(xiàng)研究的目的是探討關(guān)于液化現(xiàn)象的表面表現(xiàn)非液化蓋層的影響。為了實(shí)現(xiàn)這個(gè)來(lái)自土耳其，臺(tái)灣和希臘在震后獲得的實(shí)地調(diào)查，收集資料和鉆孔液化價(jià)值潛力指數(shù)在每個(gè)站點(diǎn)（lpi）的結(jié)果。大部分的鉆孔在液化現(xiàn)象用幾個(gè)非液化鉆孔點(diǎn)觀察。隨后，開(kāi)發(fā)了一個(gè)依據(jù)估計(jì)覆蓋層的厚度和勞工生產(chǎn)力指數(shù)的圖表，這里液化和非液化的例子被策劃著。這項(xiàng)研究的結(jié)果，可能出現(xiàn)的，液化現(xiàn)象可能與不可能的被描述成這個(gè)相對(duì)于勞工生產(chǎn)力指數(shù)的覆蓋層厚度圖。本研究成果可用于液化引起的地面干擾和為緩解這一地質(zhì)災(zāi)害的預(yù)測(cè)。1.簡(jiǎn)介該土壤

2、層的液化潛能評(píng)估是必要的，如果損壞建筑物和其他基礎(chǔ)設(shè)施被避免。一些科學(xué)家已經(jīng)研究并提出了對(duì)土層液化潛能評(píng)估方法，雖然很少有研究報(bào)告或報(bào)告液化引起的地面變形。盡管youd&garris（1955年）得出結(jié)論認(rèn)為，能夠準(zhǔn)確地預(yù)測(cè)其表面破壞的潛力是一個(gè)地質(zhì)學(xué)家擔(dān)負(fù)著與建設(shè)工程選址安全的主要工作。ishihara (1985年)用經(jīng)驗(yàn)提出的標(biāo)準(zhǔn)評(píng)估地面，通過(guò)關(guān)聯(lián)的上覆非液化層，h1型，（覆蓋層）和液化層厚度，氫氣，它的下方厚度。圖表的開(kāi)發(fā)被相關(guān)的地面峰值加速度和建議之間發(fā)生的邊界曲線和非液化的表面效應(yīng)發(fā)生不同厚度這兩個(gè)參數(shù)值（sonmez等，2008年）。由ishihara（1985年）收集的

3、資料來(lái)自無(wú)論1983年n ihonkai，日本中部地震（m= 7.7）和1976年的中國(guó)唐山大地震（m= 7.8）的有無(wú)兩次地震引發(fā)的液化。在日本橋代碼公布的標(biāo)準(zhǔn)是適用于估計(jì)土層的厚度和液化潛能。20世紀(jì)90年代，youdgarris（1995年）使用308個(gè)鉆孔數(shù)據(jù)記錄，從那里可以預(yù)期或注意到液化后15個(gè)震級(jí)5.3級(jí)至8.0級(jí)（m）的范圍地震領(lǐng)域。他們使用seed等人（1985年）創(chuàng)造的程序，簡(jiǎn)化的程序來(lái)計(jì)算土層的厚度。研究中的一個(gè)重要參數(shù)是，材料極易液化。youdgarris（1995年）把表層效應(yīng)分成三組：砂翻滾和無(wú)側(cè)位移的小地裂縫；砂翻滾加上地面振動(dòng)的影響和通過(guò)橫向傳播引起的表面效應(yīng)。

4、此外，他們開(kāi)發(fā)的領(lǐng)域，并沒(méi)有體現(xiàn)在地面液化第四組。圖1 圖表關(guān)聯(lián)液化與非液化蓋層厚度嚴(yán)重指數(shù)，以便確定在地面的存在或缺乏明確的液化區(qū)（sonmez等，2008年）。他們的結(jié)論是，發(fā)生或不發(fā)生液化是在沒(méi)有通過(guò)橫向傳播或地面的振動(dòng)影響的地點(diǎn)，由ishihara（1985年）所提出的圖大概正確的預(yù)測(cè)，對(duì)該點(diǎn)液化引起地面的振動(dòng)和橫向擴(kuò)散效應(yīng)進(jìn)行了觀察，簡(jiǎn)單的預(yù)測(cè)（youdgarris，1995年）。此外，yuan等人（2003年）和chu等人（2004年）所提出的圖表應(yīng)用了ishihara（1985年）與1999年集集大地震相關(guān)的案例。前者研究的結(jié)論是這些圖只有少數(shù)例外匹配這個(gè)數(shù)據(jù)，后者液化位點(diǎn)的方法

5、與ishihara（1985年）不一致。sonmez等人（2008年）設(shè)計(jì)的評(píng)估液化在地面的體現(xiàn)的新圖表通過(guò)關(guān)聯(lián)與非液化層厚度的上限液化嚴(yán)重程度指數(shù)（lsi）的效果。他們的收集的數(shù)據(jù)由土耳其和臺(tái)灣發(fā)生在1999年的地震引發(fā)液化和非液化地點(diǎn)完成的現(xiàn)場(chǎng)測(cè)試。被提到的圖表（圖1）分為三個(gè)區(qū)，定義為：其中液化引起的地面破壞，可觀察（a區(qū)），液化引起的地面破壞可能是沒(méi)有觀察到（c區(qū)）和過(guò)渡區(qū)a和c之間的區(qū)域（b區(qū)）。然而，正如sonmez等人（2008年）指出，ishihara的過(guò)程只考慮到了覆蓋層和底層液化層，而不考慮一個(gè)交替存在大量液化和非液化層和他們的聯(lián)合影響。sonmez等人（2008年）用液化

6、嚴(yán)重程度指數(shù)代替液化層的厚度。這項(xiàng)研究避免了開(kāi)發(fā)一個(gè)可用于此限制使用的圖表，該圖表可用于預(yù)測(cè)液化表面形式，該表現(xiàn)形式以非液化蓋層、h與液化潛能指數(shù)（lpi）相關(guān)的厚度為基礎(chǔ)。選擇該指數(shù)的勞工生產(chǎn)力指數(shù)，是因?yàn)樗辉S多研究者（iwasaki等人1978年；sonmez等人，2003年；papathanassiou，2008年；霍爾澤，2008年）認(rèn)為可以描述整個(gè)土柱的性能。那些在這項(xiàng)研究中所使用的數(shù)據(jù)被用于按地區(qū)提供了與標(biāo)準(zhǔn)貫入試驗(yàn)進(jìn)行測(cè)試，在kocaeli，1999年的土耳其，集集，1999年的臺(tái)灣和雷夫卡達(dá)，2003年的希臘的事件后。2.編制數(shù)據(jù)集和估計(jì)的勞工生產(chǎn)力指數(shù)2.1數(shù)據(jù)集在這項(xiàng)研究

7、中，papathanassiou（2008年）編制的數(shù)據(jù)集被使用。這包括在臺(tái)灣，土耳其和希臘震后的79標(biāo)準(zhǔn)貫入試驗(yàn)鉆孔液化和非液化點(diǎn)收集的鉆孔。資料來(lái)自1999年集集和臺(tái)灣的地震，http//lifelindes/research和/chichi/tw-liq/in現(xiàn)場(chǎng)- test.html。信息來(lái)自1999年科來(lái)自1999年科賈埃利地震，下載自/publications/turkey。數(shù)據(jù)來(lái)自2003年的雷夫卡達(dá)，希臘地震，獲得了由科德9六方會(huì)談（2004年）收集

8、鉆孔。臺(tái)灣標(biāo)準(zhǔn)貫入試驗(yàn)數(shù)據(jù)來(lái)自進(jìn)行了觀察和地點(diǎn)沒(méi)有液化的證據(jù)的橫向擴(kuò)展，建筑物沉降或砂翻滾。來(lái)自土耳其的標(biāo)準(zhǔn)貫入試驗(yàn)數(shù)據(jù)從adapazari小鎮(zhèn)，在那里觀察了如沙翻滾和建筑物沉降現(xiàn)象，并在那里觀察了液化引起的橫向擴(kuò)散現(xiàn)象（布雷等人，2001年）。來(lái)自2003年希臘的雷夫卡達(dá)地震的六方會(huì)談的鉆孔主要在島內(nèi)市。2.2評(píng)估對(duì)液化安全系數(shù)得到土柱的lpi在這項(xiàng)研究中，每一層的fs液化安全系數(shù)，最初是作為檔案室（循環(huán)阻力比）的比例，在企業(yè)社會(huì)責(zé)任（循環(huán)應(yīng)力比）的基礎(chǔ)上，確定的程序計(jì)算，通常被稱為“簡(jiǎn)化程序”（seed & idriss，1971年；seed的等人，1985年 和youd等人，20

9、01年)。在集集（臺(tái)灣），科賈埃利（土耳其）和雷夫卡達(dá)（希臘）地震的震級(jí)兆瓦分別為7.6，7.4和6.2。平均峰值在炎陵縣，南投，霧峰，大春和zangbin臺(tái)灣城鎮(zhèn)水平加速度分別為0.18g，為0.38 g，0.67g（楚等人，2004年）和0.19g，0.12g（莊，2002年）?？瀑Z埃利地震為1999年城鎮(zhèn)標(biāo)準(zhǔn)貫入試驗(yàn)鉆孔制定的數(shù)據(jù)是從在adapazari和亞洛瓦，那里的pga的記錄值等于0.4g。最大地表加速度的雷夫卡達(dá)城（希臘）記錄得0.42g（itsak，2003年），而在美國(guó)pga vassiliki和nydri村莊估計(jì)分別為0.25g和0.4g，（christaras等人，200

10、5年）。用液化潛能指數(shù)（lpi）來(lái)計(jì)算每個(gè)鉆孔。這種方法是由iwasaki等人（1982年），以更好地估計(jì)可能液化損害。使用的勞工生產(chǎn)力指數(shù)的計(jì)算公式如下： lpi=f(z)w(z)dz (1)其中z是地面以下的深度，其計(jì)算為w（z）= 10 - 0.5z；f（z）是對(duì)液化的安全系數(shù)fs，其中當(dāng)fs < 1時(shí)， f(z) = 1 fs；如果fs>1，那么f(z) = 0。eq（1）表現(xiàn)為一個(gè)從0到100的值的lpi。勞工生產(chǎn)力指數(shù)是和安全系數(shù)（fs）聯(lián)系在一起的。只有土壤的fs<1并且在同一時(shí)間滿足液化敏感性標(biāo)準(zhǔn)才作用于液化嚴(yán)重性(juang 和 li,，2007年)。在這項(xiàng)

11、研究中，當(dāng)ll <37和pi<12時(shí)，土層被定性為易液化，它是由seed等人提出的（2003年）。勞工生產(chǎn)力指數(shù)指數(shù)綜合了液化層厚度，對(duì)非液化（蓋）層厚度和消除對(duì)液化值的安全系數(shù)。iwasaki等人（1982年）校準(zhǔn)的液化引起的損害程度與勞工生產(chǎn)力指數(shù)值使用了87鉆孔在日本提供的液化和非液化標(biāo)準(zhǔn)貫入試驗(yàn)值的數(shù)據(jù)點(diǎn)。根據(jù)iwasaki等人（1982年）液化破壞潛能在>15（非常高）到0（極低）的范圍內(nèi)，即高5到15之間，低0和5之間。勞工生產(chǎn)力指數(shù)的方法被sonmez（2003年）修改，加入了1.2而不是1的安全系數(shù)值，并引入了兩個(gè)新的類(lèi)別較低值：0不液化，0-2液化低和2-

12、5溫和液化。對(duì)勞工生產(chǎn)力指數(shù)的優(yōu)點(diǎn)是，它通過(guò)提供量化為整個(gè)土柱的安全因素，而不是而不是為每個(gè)層的安全因素。因此，勞工生產(chǎn)力指數(shù)值分別用于液化危害圖的編制，可以用來(lái)作為一種工具來(lái)為規(guī)劃者的液化潛能的初步評(píng)估。3. 評(píng)價(jià)液化現(xiàn)象的發(fā)生為了評(píng)估非液化蓋層的厚度，h，適用的標(biāo)準(zhǔn)被papathanassiou（2008年）考慮在內(nèi)。尤其是作為土壤非液化層的特點(diǎn)要滿足一個(gè)或多個(gè)下列條件：非飽和土，液化安全系數(shù)大于1（fs>1），和塑性指數(shù)pi> 12或液限> 37。這些非敏感性的標(biāo)準(zhǔn)，由seed等人（2003年）提出的。因此，考慮到lpi和h的估計(jì)值，開(kāi)發(fā)了一個(gè)圖表，如圖2所示。與觀察到

13、的液化點(diǎn)的區(qū)別來(lái)自非液化，從而相對(duì)區(qū)的劃定。此外，一個(gè)介于這兩個(gè)區(qū)的存在，可以被視為“灰色地帶”，其中50的數(shù)據(jù)繪制相應(yīng)的液化點(diǎn)和50非液化點(diǎn)。為液化在地面表現(xiàn)值被定義為勞工生產(chǎn)力指數(shù)= 10。低于這個(gè)界限，在地面的觀測(cè)沒(méi)有液化的證據(jù)。如不液化蓋層厚度超過(guò)6米的特點(diǎn)是不液化，對(duì)勞工生產(chǎn)力指數(shù)值無(wú)關(guān)。該參數(shù)定義的液化區(qū)，如圖2所示，勞工生產(chǎn)力>10和h <4米。因此，擁有這些特征的點(diǎn)應(yīng)該被視為發(fā)生液化表現(xiàn)的能力?！盎疑貛А笔侵改睦锏膌pi>10和蓋層厚度在4-6米范圍內(nèi)。這些點(diǎn)被繪制在這方面應(yīng)作為液化表面表現(xiàn)的可能地點(diǎn)分類(lèi)。比較圖2與sonmez等人（2008年）提出的圖表（

14、圖1），從它可以看出，他們?cè)陉P(guān)于液化的發(fā)生與該覆蓋層厚度的關(guān)系是大致一致的。特別是，sonmez等人（2008年），如圖1所示，結(jié)論是液化在蓋層值h大于6米的地方不能預(yù)測(cè)，同時(shí)對(duì)h <3米液化引起的地面破壞可以預(yù)測(cè)。在我們的研究表明，這些值是分別在6米和4不發(fā)生和發(fā)生液化。圖2 勞工生產(chǎn)力指數(shù)的79個(gè)記錄包含在數(shù)據(jù)集（實(shí)心圓：液化點(diǎn)；空心圓：非液化點(diǎn)）及相關(guān)區(qū)劃定。4. 應(yīng)用該方法的拉里薩，希臘城市本研究提出的方法是應(yīng)用在拉里薩，希臘中部的城市。這座城市位于色薩利，希臘中部，是金融和商業(yè)活動(dòng)的重要中心。拉里薩市位于地震多發(fā)、中等地震活動(dòng)的地區(qū)，所在的0.24g基巖點(diǎn)有10的概率（鉑）超過(guò)

15、50年，已經(jīng)被確定使用希臘抗震規(guī)范。歷史報(bào)告中描述的發(fā)生在1941年地震后，砂翻滾和沿pinios江橫向蔓延在城市的北部，發(fā)生在1941年三月一號(hào)的地震（maravelakis，1943年）。該區(qū)的程度，可能會(huì)被表面表現(xiàn)的液化影響，通過(guò)估算液化潛能指數(shù)lpi及對(duì)在六方會(huì)談的53個(gè)地點(diǎn)收集的非液化覆蓋層厚度。此數(shù)據(jù)多數(shù)是由私人公司georesearch收集，拉里薩，其余由tsotsospitilakis（1995年）進(jìn)行的一項(xiàng)研究中收集。最初，土層液化敏感性的評(píng)估是根據(jù)由seed等人（2003年）提出的建議和之后的，對(duì)安全系數(shù)和低截獲概率進(jìn)行了計(jì)算，每孔使用2.2節(jié)所述的步驟。然而，多數(shù)拉里薩的

16、城市是建立在河流相沉積，還決定在最終調(diào)查加速度值在近地表地質(zhì)的影響。為了放大效應(yīng)，由于地表地質(zhì)，由stewart等人（2003年）提出的回歸法，導(dǎo)致一澳瑪值等于0.25g。在非液化層厚度上限確定使用papathanassiou（2008年）和上述標(biāo)準(zhǔn)。從這些地點(diǎn)的結(jié)果，繪制了使用參數(shù)勞工生產(chǎn)力指數(shù)和h，如圖3所示。只有兩幅繪制符合“液化表現(xiàn)”地帶。特別是，lpi及這些鉆孔的h（點(diǎn)），49和9的計(jì)算值是前者17個(gè)和3，后者21和3米。因此，液化引起的地面破壞，預(yù)測(cè)由地震中的m = 7和pga = 0.25g這兩個(gè)地點(diǎn)附近觸發(fā)。在圖4中的拉里薩圖所示，包括標(biāo)準(zhǔn)貫入試驗(yàn)鉆孔的點(diǎn)在內(nèi)。圖3 圖顯示了通

17、過(guò)在拉里薩（實(shí)心三角形）城市的現(xiàn)場(chǎng)測(cè)試提供的數(shù)據(jù)分布。 圖4 地圖顯示中的城市拉里薩和地區(qū)分布的鉆孔為本研究中提出的程序的液化分類(lèi)。這一結(jié)果不與地表地質(zhì)為基礎(chǔ)的評(píng)估在拉里薩地區(qū)河流的地方液化敏感性，容易液化，沉積物映射一致。但是，低（深）地下水位和致密層的底土（標(biāo)準(zhǔn)貫入試驗(yàn)- n> 25）認(rèn)為導(dǎo)致這種非液化的行為和解釋由本研究所提出的方法的應(yīng)用成果的主要參數(shù)。參考書(shū)目bray, j.d., sancio, r.b., youd, l.f., durgunoglu, t., onalp, a., cetin, o.k., seed, r.b., stewart, j.p.,christen

18、sen, c., baturay, m.b., karadayilar, t. & emrem, c. 2001. 記錄事件所引起的地表塌陷的原因,1999年8月17日土耳其地震:報(bào)道在地表環(huán)境數(shù)據(jù)的特征(2001)p。588。christaras, b., pavlides, s.p. & papathanassiou, g. 2005. 研究包括地表斷裂。 從2003年案例研究(希臘)地震地質(zhì)、線性國(guó)際學(xué)術(shù)研討會(huì),法國(guó)里昂基礎(chǔ)設(shè)施(2005)(cd)。chu, d.b., stewart, j.p., lee, s., tsai, j.s., lin, p.s., chu,

19、 b.l., seed, r.b., hsu, s.c., yu, m.s. &wang, m.c.h. 2004. 研究臺(tái)灣九二一地震液化和無(wú)液化條件下的土壤(。土動(dòng)力學(xué)和地震工程24:647-657。holzer, t.l. (2008). 液化概率風(fēng)險(xiǎn)圖。巖土地震工程土動(dòng)力學(xué)四，普惠制181，asce的。ishihara, k. 1985. 天然地震中土的穩(wěn)定性、觸發(fā)性。第11屆全球會(huì)議土力學(xué)及基礎(chǔ)工程，舊金山，加州，鹿特丹1:321-376。itsak, 2003. 2003年8月14日，雷夫卡達(dá)地震和他對(duì)建筑和大自然的影響，見(jiàn)報(bào)告（2003年），地震61（希臘）。iwasak

20、i, t., tatsuoka, f., tokida, k. & yasuda, s. 1978. 一個(gè)評(píng)估潛在的土壤液化在日本各網(wǎng)站案例分析實(shí)用方法。第二屆國(guó)際會(huì)議小區(qū)劃：885-896。iwasaki, t., tokida, k., tatsuoka, f., watanabe, s., yasuda, s. & sato, h. 1982. 土壤液化潛能小區(qū)劃使用簡(jiǎn)化方法。訴訟的第13屆小區(qū)劃，西雅圖，美國(guó)第一卷國(guó)際會(huì)議。三，1319年至1330年。juang, c.h., yuan, h., lee, der-her. & ku, c.s. 2002.液化評(píng)

21、估與從臺(tái)灣地震重點(diǎn)評(píng)價(jià)彩管的案件為基礎(chǔ)的方法。土動(dòng)力學(xué)和地震工程22：241-258。maravelakis (1943). 地質(zhì)和拉里薩破壞性地震強(qiáng)震研究，1941年3月1日，第27papathanassiou, g. 2008.生產(chǎn)力指數(shù)的方法用于校準(zhǔn)液化引起的故障的嚴(yán)重程度和評(píng)估液化表面證據(jù)，工程地質(zhì)。 96:94-104。seed, h.b. & idriss, i.m. 1971. 簡(jiǎn)化程序，評(píng)價(jià)土壤液化過(guò)程。作者：土力學(xué)基礎(chǔ)部，asce的97（sm9）:1249- 1273seed, h.b., tokimatsu, k., harder, l.f. & chung

22、, r.m. 1985. 在土壤液化標(biāo)準(zhǔn)貫入試驗(yàn)性評(píng)價(jià)程序的影響。地質(zhì)工程部的雜志111（12）:1425- 1445。stewart, j.p., liu, a.h. & choi, y. 2003. 在構(gòu)造活動(dòng)區(qū)譜加速度放大系數(shù)。美國(guó)地震學(xué)會(huì)通報(bào)，93（1）：332-352;分類(lèi)號(hào)：10.1785/0120020049sonmez, h. 2003.修改的液化潛能指數(shù)和一個(gè)液化易發(fā)區(qū)（inegol-土耳其）液化災(zāi)害空間。環(huán)境地質(zhì)44（7）:862- 871sonmez, b., ulusay, r. & sonmez, h. 2008. 一個(gè)液化引起地面上的故障識(shí)別研究，并

23、以1999年科賈埃利集集地震為依據(jù)，工程地質(zhì)，97個(gè)計(jì)算數(shù)據(jù)：112-125。investigating the effect of the thickness of the surficial non-liquefiable layer to the surface manifestation of liquefaction-induced failures g. papathanassiou department of geology, aristotle university of thessaloniki, greeceabstract: the aim of this study w

24、as to investigate the influence of thenon-liquefiable cap layer on the surface manifestations of liquefaction phenomna. in order to achieve this information from boreholes in turkey, taiwan and greece, obtained during post-earthquake field investigations, were collected and thevalue of liquefaction

25、potential index (lpi) at each site was determined.most of borings were at places where liquefaction phenomena was observed,with a few drilled at non-liquefied sites.afterwards, a diagram was developed based on the estimated thickness of the cap layer (h) and he value of lpi, where the liquefied and

26、non-liquefied cases were plotted. as a result of this study, zonesof likely, possible and unlikely occurrence of liquefaction manifestation were delineated into this diagram of lpi versus the thickness of the cap layer.the outcome of this research can be used for the prediction of liquefaction-induc

27、ed ground disruption and for the mitigation ofthis geological hazard. 1.brief introduction the evaluation of the liquefaction potential of a soil layer is necessary if damage to buildings and other infrastructure is to be avoided. several scientistshave studied and proposed approaches for the evalua

28、tion of the liquefaction potential of a soil layer although few reports examine or report on liquefactioninduced ground deformation. this is despite youd & garris (1995) concludingthat the ability to accurately predict the potential for ground-surface disruption is a major concern for geotechnol

29、ogists charged with the safe siting of constructed works. ishihara (1985) proposed empirical criteria for assessing the likelihood of liquefaction manifesting at the ground surface by correlating the thickness of the overlying non-liquefiable layer, h 1, (cap layer) and thicknesses of the liquefiabl

30、e layers, h 2, beneath it. the chart developed correlated these two parameters of thicknesses with the value of peak ground acceleration and proposed boundary curves for discriminating between occurrence and non-occurrence of surface effects of liquefaction (sonmez et al., 2008). the data collected

31、by ishihara (1985) comes from areas with and without liquefaction triggered by two earthquakes,the 1983 nihonkai-chubu earthquake of japan (m = 7.7) and the 1976 tangshan earthquake of china (m = 7.8). the criteria published in the japanese bridge code were applied to estimate the the thicknesses an

32、d liquefaction potential of the soil layers. in the 1990's, youd & garris (1995) used a data set of 308 borehole logs from areas where liquefaction could be expected or was noted after 15 earthquakes ranging in magnitude (m) from m5.3 to m8.0.they used the proceduredeveloped by seed et al. (

33、1985), the simplified procedure, for the calculation of layer thicknesses. an important parameter in the study is that the materialsare highly susceptible to liquefaction. youd & garris (1995) classified the surface effects into three groups: sand boils and small ground fissures without lateral

34、ground displacement; sand boilsplus the effects of ground oscillation; and surface effects induced by lateral spreads. in addition,they developed a fourth group for areas that did not manifestfigure 1. chart correlating liquefaction severity index with the thickness of non liquefiable cap layer in o

35、rder to define zones defined by the presence or absence of liquefaction at the ground surface(sonmez et al., 2008). they concluded that the occurrence or not of liquefaction effects at the ground surface for sites not affected by lateral spread or ground oscillation are generally correctly predicted

36、 by the diagrams proposed by ishihara (1985) and that sites where liquefaction-induced ground oscillation and lateral spreading effects were observed, are poorly predicted (youd & garris, 1995).furthermore, yuan et al. (2003) and chu et al. (2004) applied the charts proposed by ishihara (1985) i

37、n cases associated with the 1999 chi-chi earthquake. the former study concluded that these diagrams match the data with only a few exceptions and the latter one that the liquefied sites were inconsistent with the method of ishihara (1985).sonmez et al. (2008) designed a new chart for assessing the p

38、otential for liquefaction effects to manifest at the ground surface by correlating the liquefaction severity index (lsi) with the thickness of non-liquefiable cap layer. their data were collected from in-situ tests performed in liquefied and non-liquefied sites triggered by the earthquakes that occu

39、rred in turkey and taiwan in 1999. the proposed chart (fig. 1) is divided in three zones,defined as:where liquefaction-induced ground surface disruption may be observed (zone a), liquefaction-induced ground surface disruption may is not observed (zone c) and a transition area between zones a and c (

40、zone b). however, as sonmez et al (2008) pointed out, the ishihara procedure only takes into account the cap layer and the underlying liquefiable layer and doesnot consider the presence of a number of alternating liquefied and nonliquefiedlayers and their combined effects. sonmez et al. (2008) used

41、the liquefaction severity index instead of the thickness of liquefiable layer. this study avoids this limitation by developing a diagram that can be used for the prediction of liquefaction surface manifestation based on the correlation of the thickness of the non-liquefiable cap layer, h, with the l

42、iquefaction potential index (lpi). this index, lpi, was selected because it can describe the performance of the whole soil column as noted by several researchers (iwasaki et al.1978;sonmez etal. 2003; papathanassiou, 2008; holzer, 2008).the data that were used in this study were provided by spt test

43、s conducted in areas with and without surface liquefaction effects after the kocaeli, turkey 1999, chi-chi, taiwan 1999 and lefkada, greece 2003 events. 2.the dataset and the estlmation of lpt2.1 the dataset in this study, the dataset compiled by papathanassiou (2008) was used. this included 79 spt

44、borings from post-earthquake in-situ tests at liquefied and non-liquefied sites in taiwan, turkey and greece were collected. data from the 1999 chi-chi, taiwan,earthquake,was downloaded from /lifelines/research_projects/3a02 and /chichi/tw-liq/in-situ-

45、test.html. information from the 1999 kocaeli earthquake, was downloaded from /publications/turkey/adapazari/index.html. data from the 2003 lefkada, greece earthquake were obtained from 9 spt borings collected by kede (2004). the taiwanese spt data was from sites where lateral

46、spreading, building settlement or sand boils were observed and sites without evidence of liquefaction. the spt data from turkey was from the town of adapazari, at sites where phenomena such as sand boils and building settlement were observed, and at sites where liquefaction-induced lateral spreading

47、 phenomena occurred (bray et al., 2001). the spt profiles, from the 2003 lefkada earthquake, greece, were drilled mainly in the municipality of the island. 2.2 evaluating the factor of safety against liquefaction to get the lpi of the soil column in this study, the factor of safety against liquefact

48、ion per layer, fs, was initially calculated as the ratio of crr (cyclic resistance ratio) to the csr (cyclic stress ratio),based on the deterministic procedure,commonly referred to as the"simplified procedure" (seed & idriss,1971;seed et al., 1985 and youd et al., 2001). the moment mag

49、nitude mw of chi-chi (taiwan), kocaeli (turkey) and lefkada (greece) earthquakes was 7.6, 7.4 and 6.2 respectively.the meanpeakhorizontal acceleration in the taiwanese towns of yanlin, nantou,wufeng,dachun and zangbin was 0.18 g, 0.38 g, 0.67 g (chu et al., 2004) and 0.19 g,0.12 g(juang, 2002),respe

50、ctively. the data set for the kocaeli 1999 earthquakeis fromspt borings in the towns of adapazari and yalova, where the recorded valuesof pga were equal to 0.4 g.the maximum ground acceleration recorded in the town of lefkada (greece) was 0.42 g (itsak, 2003) while in the villages of vassiliki and n

51、ydri the pga was estimated as 0.25 g and 0.4 g, respectively (christaras et al., 2005). the liquefaction potential index (lpi) was calculated for each borehole.thisapproach was proposed by iwasaki et al. (1982) to better estimate the potentialliquefaction damage.the lpi is calculated using the follo

52、wing equation: lpi=f(z)w(z)dz (1) where z is the depth below the ground surface in meters and is calculatedas w(z) = 10 - 0.5z; f(z) is a function of the factor of safety against liquefaction, fs, where f(z)=1-fs when fs<1 and if fs>1 than f(z)=0.eq.(1) expresses the lpi as a value ranging fro

53、m 0 to 100. the lpi is related to the factorofsafety (fs).only soils where fs<1 and that satisfy at the same time the liquefaction susceptibility criteria contribute to the severity of liquefaction (juang & li, 2007). in this study, a soil layer was characterized as susceptible to liquefactio

54、n when the ll<37 and pi < 12, as it was proposed by seed et al. (2003), the lpi index combines the thickness of the liquefiable layer, the thicknessof the non- liquefiable (cap) layer and the value of the factor of safety againstliquefaction. iwasaki et al. (1982) calibrated the severity of li

55、quefaction-induceddamages with the lpi values using data provided by 87 borings with spt values in liquefied and non-liquefied sites in japan. accord- ing to iwasaki et al.(1982) liquefaction failure potential ranges from >15 (extremely high) to 0 (extremely low), i.e. high is between 5 and 15 an

56、d low between 0 and 5. the lpi methodology was modified by sonmez (2003), by adding a threshold value of 1.2 instead of 1 for the factor of safety and by introducing two new categories for the lower values: 0 non-liquefiable; 0-2 low liquefiable and 2 and 5 moderate liquefiable. the advantage of lpi

57、 is that it quantifies the likelihood of liquefaction at the site by providing a unique value for the entire soil column instead of factors of safety for each of the layers. consequently, the lpi values were used for the compilation of liquefaction hazard maps which can be used by planners as a tool

58、 for the preliminary assessment of the liquefaction potential. 3 evaluating the occurrence of liquefaction manifestations in order to assess the thickness, h, of the non liquefiable cap layer,the criteria applied by papathanassiou (2008) were taken into account. in particular, as non-liquefiable lay

59、er is characterized as a soil that is meeting one or more ofthe following criteria:unsaturated soil, factor of safety against liquefaction more than 1 (fs>1), and plasticity index pi>12 or liquid limit ll>37. these nonsusceptibility criteria were proposed by seed et al. (2003). thus,taking into account the estimated values of lpi and h, a diagram i