不良地基土及處理方法中英對照

1、不良地基土與地基處理方法 摘 要:地基基礎工程對于高層建筑的安全及使用至關重要其造價高、工期長?？茖W合理地選擇地基處理方式對于現(xiàn)代土木工程建設有著重要的意義。 關鍵詞:地基土地基地基處理1. 常見不良地基土及其特點1.軟粘土 軟粘土也稱軟土，是軟弱粘性土的簡稱。它形成于第四紀晚期，屬于海相、瀉湖相、河谷相、湖沼相、溺谷相、三角洲相等的粘性沉積物或河流沖積物。多分布于沿海、河流中下游或湖泊附近地區(qū)。常見的軟弱粘性土是淤泥和淤泥質土。軟土的物理力學性質包括如下幾個方面：（1）物理性質 高粘粒含量、高含水量、大孔隙比，因而其力學性質也就呈現(xiàn)與之對應的特點-低強度、高壓縮性、低滲透性、高靈敏度（2）力

2、學性質 軟粘土的強度極低 軟粘土的壓縮性很大 滲透系數(shù)很小3工程特性 軟粘土地基承載力低，強度增長緩慢；加荷后易變形且不均勻；變形速率大且穩(wěn)定時間長；具有滲透性小、觸變性及流變性大的特點。常用的地基處理方法有預壓法、置換法、攪拌法等。1.2 雜填土 雜填土主要出現(xiàn)在一些老的居民區(qū)和工礦區(qū)內，是人們的生活和生產(chǎn)活動所遺留或堆放的垃圾土。這些垃圾土一般分為三類：即建筑垃圾土、生活垃圾土和工業(yè)生產(chǎn)垃圾土。 雜填土的主要特點是無規(guī)劃堆積、成分復雜、性質各異、厚薄不均、規(guī)律性差。因而同一場地表現(xiàn)為壓縮性和強度的明顯差異，極易造成不均勻沉降，通常都需要進行地基處理。1.3 沖填土 沖填土是人為的用水力沖填

3、方式而沉積的土。近年來多用于沿海灘涂開發(fā)及河漫灘造地。沖填土地基一般具有如下一些重要特點。 顆粒沉積分選性明顯同時在深度方向上存在明顯的層理。2 沖填土的含水量較高，一般大于液限，呈流動狀態(tài)。3 沖填土地基早期強度很低，壓縮性較高1.4 飽和松散砂土 粉砂或細砂地基在靜荷載作用下常具有較高的強度。但是當振動荷載地震、機械振 動等作用時，飽和松散砂土地基則有可能產(chǎn)生液化或大量震陷變形，甚至喪失承載力。常用的處理方法有擠出法、振沖法等。1.5 濕陷性黃土 在上覆土層自重應力作用下，或者在自重應力和附加應力共同作用下，因浸水后土的結構破壞而發(fā)生顯著附加變形的土稱為濕陷性土 在濕陷性黃土地基上進行工程

4、建設時，必須考慮因地基濕陷引起附加沉降對工程可能造成的危害，選擇適宜的地基處理方法，避免或消除地基的濕陷或因少量濕陷所造成的危害。1.6 膨脹土 膨脹土的礦物成分圭要是蒙脫石，它具有很強的親水性，吸水時體積膨脹，失水時體積收縮。這種脹縮變形肚往很大，極易對建筑物造成損壞。 常用的地基處理方法有換土、土性改良、預浸水，以及防止地基土含水量變化等工程措施。1.7 含有機質土和泥炭土 當土中含有不同的有機質時，將形成不同的有機質土，在有機質含量超過一定含量時就形成泥炭土，它具有不同的工程特性，有機質的含量越高，對土質的影響越大，主要表現(xiàn)為強度低、壓縮性大，并且對不同工程材料的摻入有不同影響等，對直接

5、工程建設或地基處理構成不利的影響。1.8 山區(qū)地基土 山區(qū)地基土的地質條件較為復雜，主要表現(xiàn)在地基的不均勻性和場地穩(wěn)定性兩個方面。由于自然環(huán)境和地基土的生成條件影響，場地中可能存在大孤石，場地環(huán)境也可能存在滑坡、泥石流、邊坡崩塌等不良地質現(xiàn)象1.9 巖溶喀斯特 在巖溶喀斯特地區(qū)常存在溶洞或土洞、溶溝、溶隙、洼地等。地下水的沖蝕或潛蝕使其形成和發(fā)展，它們對結構物的影響很大，易于出現(xiàn)地基不均勻變形、崩塌和陷落。第 2 節(jié) 地基處理方法2.1 置換法1換填法 就是將表層不良地基土挖除，然后回填有較好壓密特性的土進行壓實或夯實，形成良好的持力層。從而改變地基的承載力特性，提高抗變形和穩(wěn)定能力。2振沖置

6、換法 利用專門的振沖機具，在高壓水射流下邊振邊沖，在地基中成孔，再在孔中分批填入碎石或卵石等粗粒料形成樁體。該樁體與原地基土組成復合地基，達到提高地基承載力減小壓縮性的目的。3夯擠置換法 利用沉管或夯錘的辦法將管錘置入土中，使土體向側邊擠開，并在管內或夯坑放人碎石或砂等填料。該樁體與原地基土組成復合地基，由于擠、夯使土體側向擠壓，地面隆起，土體超靜孔隙水壓力提高，當超靜孔隙水壓力消散后土體強度也有相應的提高。2.2 預壓法1堆載預壓法 在建造建筑物之前，用臨時堆載砂石料、土料、其他建筑材料、貨物等的方法對地基施加荷載，給予一定的預壓期。使地基預先壓縮完成大部分沉降并使地基承載力得到提高后，卸除

7、荷載再建造建筑物。2真空預壓法 在軟粘土地基表面鋪設砂墊層，用土工薄膜覆蓋且周圍密封。用真空泵對砂墊層抽氣，使薄膜下的地基形成負壓。隨著地基中氣和水的抽出，地基土得到固結。為了加速固結，也可采用打砂井或插塑料排水板的方法，即在鋪設砂墊層和土工薄膜之前打砂井或插排水板，達到縮短排水距離的目的。3降水法 降低地下水位可減少地基的孔隙水壓力增加上覆土自重應力，使有效應力增加，從而使地基得到預壓。這實際上是通過降低地下水位，靠地基土自重來實現(xiàn)預壓目的。4電滲法 在地基中插入金屬電極并通以直流電，在直流電場作用下，土中水將從陽極流向陰極形成電滲。不讓水在陽極補充而從陰極的井點用真空抽水，這樣就使地下水位

8、降低，土中含水量減少。從而地基得到固結壓密，強度提高。電滲法還可以配合堆載預壓用于加速飽和粘性土地基的固結。2.3 壓實與夯實法（1）表層壓實法 采用人工夯，低能夯實機械、碾壓或振動碾壓機械對比較疏松的表層土進行壓實。也可對分層填筑土進行壓實。當表層土含水量較高時或填筑土層含水量較高時可分層鋪墊石灰、水泥進行壓實，使土體得到加固。（2）重錘夯實法 重錘夯實就是利用重錘自由下落所產(chǎn)生的較大夯擊能來夯實淺層地基，使其表面形成一層較為均勻的硬殼層，獲得一定厚度的持力層。（3）強夯 強夯是強力夯實的簡稱。將很重的錘從高處自由下落，對地基施加很高的沖擊能，反復多次夯擊地面，地基土中的顆粒結構發(fā)生調整，土

9、體變?yōu)槊軐崳瑥亩茌^大限度提高地基強度和降低壓縮性。2.4 擠密法（1）振沖密實法 利用專門的振沖器械產(chǎn)生的重復水平振動和側向擠壓作用，使土體的結構逐步破壞，孔隙水壓力迅速增大。由于結構破壞，土粒有可能向低勢能位置轉移，這樣土體由松變密。（2）沉管砂石樁碎石樁、灰土樁、og 樁、低標號樁等 利用沉管制樁機械在地基中錘擊、振動沉管成孔或靜壓沉管成孔后，在管內投料，邊投料邊上提振動沉管形成密實樁體，與原地基組成復合地基。（3）夯擊碎石樁塊石墩 利用重錘夯擊或者強夯方法將碎石塊石夯人地基，在夯坑里逐步填人碎石塊石反復夯擊以形成碎石樁或塊石墩。2.5 拌和法（1）高壓噴射注漿法高壓旋噴法以高壓力使水泥

10、漿液通過管路從噴射孔噴出，直接切割破壞土體的同時與土拌和并起部分置換作用。凝固后成為拌和樁柱體，這種樁柱體與地基一起形成復合地基。 也可以用這種方法形成擋土結構或防滲結構。（2）深層攪拌法 深層攪拌法主要用于加固飽和軟粘土。它利用水泥漿體?嗷蚴曳厶遄魑鞴袒粒錳刂頻納畈憬漣杌到袒了腿說鼗林杏臚燎恐平漣瑁緯傷嗍彝戀淖澹朐鼗槌篩春系鼗嗤磷奈錮砹災嗜【鲇詮?化劑與土之間所產(chǎn)生的一系列物理-化學反應。固化劑的摻人量及攪拌均勻性和土的性質是影響水泥土樁柱性質以至復合地基強度和壓縮性的主要因素。2.6 加筋法（1）土工合成材料 土工合成材料是一種新型的巖土工程材料。它以人工合成的聚合物，如塑料、化纖、合成橡

11、膠等為原料，制成各種類型的產(chǎn)品，置于土體內部、表面或各層土體之間，發(fā)揮加強或保護土體的作用。土工合成材料可分為土工織物、土工膜、特種土工合成材料和復合型土工合成材料等類型。（2）土釘墻技術 土釘一般是通過鉆孔、插筋、注漿來設置，但也有通過直接打人較粗的鋼筋和型鋼、鋼管形成土釘。土釘沿通長與周圍土體接觸，依靠接觸界面上的粘結摩阻力，與其周圍土體形成復合土體，土釘在土體發(fā)生變形的條件下被動受力。并主要通過其受剪工作對土體進行加固，土釘一般與平面形成一定的角度，故稱之為斜向加固體。土釘適用于地下水位以上或經(jīng)降水后的人工填土、粘性土、弱膠結砂土的基坑支護和邊坡加固。3加筋土 加筋土是將抗拉能力很強的拉

12、筋埋置于土層中，利用土顆粒位移與拉筋產(chǎn)生的摩擦力使土與加筋材料形成整體，減少整體變形和增強整體穩(wěn)定。拉筋是一種水平向增強體。一般使用抗拉能力強、摩擦系數(shù)大而耐腐蝕的條帶狀、網(wǎng)狀、絲狀材料，例如，鍍鋅鋼片；鋁合金、合成材料等。2.7 灌漿法 是利用氣壓、液壓或電化學原理將能夠固化的某些漿液注入地基介質中或建筑物與地基的縫隙部位。灌漿的漿液可以是水泥漿、水泥砂漿、粘土水泥漿、粘土漿、石灰漿及各種化學漿材如聚氨酯類、木質素類、硅酸鹽類等。根據(jù)灌漿的目的可分為防滲灌漿、堵漏灌漿、加固灌漿和結構糾傾灌漿等。按灌漿方法可分為壓密灌漿、滲入灌漿、劈裂灌漿和電化學灌漿。灌漿法在水利、建筑、道橋及各種工程領域有

13、著廣泛的應用。 參考文獻1.基礎工程，華南理工大學等編，中國建筑工業(yè)出版社，20082.建筑地基處理技術規(guī)程jgj79-20023.地基基礎設計與計算，人民交通出版社，20054.簡明地基基礎設計施工手冊，中國建筑工業(yè)出版社，20035.地基處理工程設計計算與施工，中國地質大學出版社，19976.foundation design and construction，geo publication no.1/2006 poor soil and foundation methodsabstract: the ground foundation engineering and uses very

14、important regarding high-rise constructionssecurityits construction cost is highthe time is long. science reasonable choice ground treatment way hasthe vital significance regarding the modern civil engineering construction.key words: foundation soilgroundground treatment1.the most common adverse soi

15、l and its characteristics1 soft claysoft clay also called soft soil the clay is weak and short. it was formed in the latequaternary a marine lagoon phase of the valley the lake is the drowning of thevalley the delta equivalent viscous alluvial sediments or river. more distributed incoastal areas mid

16、dle and lower reaches of rivers or lakes nearby areas. the weaknessis common clay mud and silt soil. soft soil of the physical and mechanical propertiesinclude the following aspects:1 physical properties:it has high clay content and high moisture content the void ratio which showed themechanical nat

17、ure of it with the corresponding features of low-intensityhigh-compression low permeability high sensitivity.2 mechanical properties:the strength of soft clay is very low.hydraulic conductivity is very slow.soft clay of the great compression.（3）engineering properties: by the garbage dumps or soil. t

18、hese waste soil generally fall into three categories:namely construction waste soil solid waste soil and industrial production of refusesoil.1.2 miscellaneous fillmiscellaneous filling occurred mainly in the neighbourhood of some old and miningareas is peoples lives and production activities leftsof

19、t clay foundation bearing capacity of low intensity slow growth easy loading afterdeformation and unevendeformation rate of large and stable long time pervasivesmall and thixotropy rheology major characteristics. the foundation used apre-pressure treatment replacement mixing method and so on. miscel

20、laneous filling the main features is the accumulation of planning complexand varied nature uneven thickness the law worse. thus the same venue for theperformance of compression and intensity of the obvious differences easily causeuneven settlement the foundation usually need to be dealt with.1.3 cho

21、ng fillingfilling is man-made water-filled way of the soil and sediments. in recent years morefor coastal shoreline development and to create river floodplain.fill the foundationgenerally has the following important features:1 （1）particles shen points clear of the election and in the direction of th

22、e depthmarked on the bedding.（2）filling the high water content generally greater than liquid a flow state.3foundation-filling low early strength higher compression which is due toless-filling in the consolidation of state.1.4 saturated loose sand fine sand or silt in the foundation under static load

23、 often have a high intensity. butwhen the vibration load earthquakes vibration etc. role saturated loose sandfoundation is likely to have a large number of seismic subsidence liquefied ordeformation or even the loss of capacity.common ways of handling out therevibro-law.1.5 collapsible loessin the c

24、asing layer themselves under stress or stress self-respect and common underadditional stress due to water damage to the structure of soil in significant additionaldeformation of the soil known as the collapsible soil.in collapsible loess foundation carrying out works on the building consideration mu

25、stbe given due to wet ground subsidence caused additional settlement of the projectmay cause harm to choose suitable method of dealing with the foundation to avoid oreliminate the foundation of collapsible or a small amount of subsidence caused by wethazard. 1.6 expansive soilexpansive soil if the m

26、ineral composition of montmorillonite-kyu it is veryhydrophilic when the water volume expansion when the volume of water losscontraction.common ground treatment method for soil soil improvement pre-soaking and theprevention of soil moisture content such as changes in engineering measures.1.7 contain

27、ing organic matter in soil and peatwhen the soil contains organic matter in a different it will be a different soil organicmatter organic matter content when it exceeds a certain form of peat it has differentcharacteristics of the projectthe higher the organic matter content the greater the impact o

28、n soil quality mainlyfor the low-intensity compression and the incorporation of different projects havedifferent effects on the direct construction or foundation treatment adversely affected.1.8 mountain soilmountain soil more complicated geological conditions mainly in the foundation ofthe uneven a

29、nd stability of both venues. as the natural environment and soilconditions affect the generation site of large boulders may exist there may be spaceenvironment landslides and mud-rock flows slope failure and other adversegeological phenomenon.1.9 karstin karst region often exist or cave-earth dissol

30、ved ditch the gap solution such asdepression. underground water erosion or potential erosion of its formation anddevelopment of their impact on the structure of the great easy to appear unevenground deformation and the collapse of the fall.2， ground treatment 2.1 replacement actand then get rid of b

31、eing bad supercrust foundation soil being dug backfill soilhaving dense fairly good pressure characteristic property carrying out the compactionor densification force forming fine holding tier. bearing the weight of changingfoundation thereby force characteristic property improves the resist deforma

32、tion andstable ability. 2 vibrate according to displacing law make use of special vibrating to rinse machines and tools rush near vibratingbelow high-handed water jet ready-made a hole in foundation fill in rude granulessuch as breakstone or pebble again in batches in kong zhong expecting forming th

33、epole body. be the pole body and plain foundation soil turn to be composed ofcompound foundation achieve rise foundation bears the weight of a forcediminishing compressibilitys purpose. 3 densification displaces lawmake the soil body push against to broadside coming untied put fillings such asperson

34、 breakstone or grit in to being in charge of an inner or to pounding a pit and inmaking use of the way sinking a tube or pounding a hammer to place hammer beingburied. be the pole body and plain foundation soil turn to be composed of compoundfoundation body side direction squeezes the floor bulges s

35、ince pushing against ramming messenger earth super-quiet small opening of soil body water pressureimprovesthink that the super-quiet small opening water pressure elimination god ofthe earth body intensity also has corresponding rise. 2.2 pre-method 1 reactor preloading law before the construction of

36、 buildings temporary surcharge aggregate soiland other construction materials goods etc. the way the foundation to impose loadto a certain pre-pressure period. foundation to complete the pre-compression most ofthe settlement and foundation bearing capacity is improved removable load to theconstruction o