【正文】 水泥土樁法，在施工中無噪音、振動(dòng)小、對(duì)環(huán)境無污染、處理后很快投入使用，適應(yīng)當(dāng)前快速施工的要求。夯實(shí)水泥土樁是一種介于剛性樁與柔性樁之間的具有一定壓縮性的樁?！? (1)= (2)式中——樁體混合料試塊邊長150mm立方體標(biāo)準(zhǔn)養(yǎng)護(hù)28天立方體抗壓強(qiáng)度平均值，KPa，夯實(shí)水泥土樁的fcu強(qiáng)度為C4～C6之間，根據(jù)當(dāng)?shù)亟?jīng)驗(yàn)及現(xiàn)場(chǎng)試驗(yàn)配比確定；——樁體截面面積，m2，；——單樁周長，m；——第 i層土的厚度，m；——樁周第I層土的側(cè)阻力特征值，KPa，由于在樁周范圍內(nèi)土質(zhì)結(jié)構(gòu)較松散，故這里不計(jì)樁周側(cè)阻力；——樁端端阻力特征值，KPa，參考勘察報(bào)告取用。：是由勘察報(bào)告提供的。由于部分土的自重及地面上的荷載通過負(fù)摩阻力傳給樁，引起樁身軸向力增加，因而負(fù)摩阻力降低了樁的承載力，增大了樁基的沉降，嚴(yán)重時(shí)，甚至?xí)斐蓸兜臄嗔?。按?）式計(jì)算得=，按（2）式計(jì)算得=，單樁豎向承載力值取兩者的較小值。將數(shù)據(jù)代入式（4），滿足規(guī)范要求。試驗(yàn)采用剛性壓板置于試樁中心點(diǎn)上，通過分級(jí)加載，觀察分析其所加荷載與沉降變形的關(guān)系，繪出P—S曲線。為對(duì)比加固前后樁間土承載力的變化，完工后，布置了3個(gè)輕便觸探點(diǎn)進(jìn)行是試驗(yàn)。(2)復(fù)合地基中由于夯實(shí)水泥土樁樁體材料僅為水泥，不配筋，充分發(fā)揮樁間土的承載力，其受力和變形類似于素混凝土樁，具有地基承載力高、變形小、穩(wěn)定快、施工簡(jiǎn)單易行、工程質(zhì)量易保證等優(yōu)點(diǎn)，工程造價(jià)一般還比CFG樁便宜，經(jīng)濟(jì)效益和社會(huì)效益非常顯著。參考文獻(xiàn)：[1]徐至均，：機(jī)械工業(yè)出版社，[2]閻明禮， 8專業(yè)外文翻譯Influence of humic acid and salt concentrationon limestabilized ariake clays and microstructure researchAbstract: This study first investigates the effects of humic acid,and salt concentration on limestabilized Ariake clays with emphasis on their mechanical results show that the strength and yield stress of limestabilized clay with high humic acid are low due to the obstruction of the pozzolanic reaction,and the effect of humic acid on strength of stabilized clays decreases with increasing salt concentration because the humic acid because inactive at higher salt concentration . Then through analyzing the microstructure feature of the stabiliaed clays,some relationship between microstructure and mechanical properties of limestabilized clays are established.Introduction:Ariake clay is a highly sensitive soft clay deposited around the coast of the Ariake Bay in Kyushu Island , nature water content varies from 50 to 200%.Most of the Ariake clays are classified as CH,and the sensitivity exceeds to its very high water content and low shear strength ,improvement of Ariake clays with in a short period is popular improvement method is to use chemical additives such as major strengh gain of limestabilized clay mainly is derived from three reactions, . hydration , ion exchange and pozzolanic reactions, in which cementing products, such as CSH(CaO－SiO2－H2O) and CAH(CaO－Al2O3－H2O), are formed.Organic matter in the clay is responsible for high plasticity, high shrinkage, high pressibility, low hydraulic conductivity, and low shear strength. It is generally accepted that the presence of the organic matter in the clay may lead to the detriment of the strength of limestabilized clays. However, some studies have shown that not all of the organic pounds really have a negative effect on the cementing process.The study first attempts to prehend the effect of humic acid, a kind of organic matter, and salt concentration on limestabilized Ariake clays. The strength and the pressibility of the limestabilized clays were investigated by unconfined pression test and consolidation tests. These tests were conducted on clays with organic matter extracted and various amounts of humic acid mixed.As salt concentration is known to be one of the dominant factors in the strength of the limestabilized clays, this study also investigated the influence of the humic acid.The observation on microstructure of soil is useful to appreciate the relationship between soil structure and its mechanical behavior. In the case of limestabilized clay, the study on the microstructure yields more information than that of nature clay owing to that the microstructure of stabilized clay is a bination of cementation bond and fabric. In the present research, the microstructure feature of the stabilized clays was observed by Atterberg limit, permeability tests, Scanning Electron Microscope(SEM) and Mercury Intrusion Porosimetre(MIP). We try to relate the mechanical results of limestabilized clay to these microstructure test results of account for the relationship between them. At last, two schematic diagrams of influence of humic acid and salt concentration on limestabilized Ariake clay will be presented.Experiment method:The Ariaka clay samples used here were obtained from (a)Okawa,area, Fukuoka Prefecture, (b)Ashikari area, Saga Prefecture, and (c)Isahaya Bay, Nagasaki prefecture, designated as Clay 1,Clay 2,and Clay 3,respectively(see table1).Quick lime was applied for the stabilization. The clays were mixed with 5,10,and 20% lime by mass of dry soil. In order to eliminate the effect of the differernces in water content, distilled water was added to Clay 2 and Clay 3 to adjust the water content to 185% that is the natural water content of Clay addition of distilled water in both clays had little effect on their salt concentrations.Table 1 Properties of Ariake claysProperties Clay 1 Clay 2 Clay 3Water content/% Liquid limet/% Plasticity index/% Specific gravity/() Sand/% 3 3 0Silt/% 29 37 19Clay/% 68 60 81 PH Salt concentration (Dichromate absorption) 。（4）是否設(shè)置褥墊層以及墊層的材料和厚度，直接影響復(fù)合地基的樁和樁間土強(qiáng)度的發(fā)揮，合理的墊層厚度對(duì)提高復(fù)合地基承載力和減少沉降變形是非常有利的。本工程低應(yīng)變檢測(cè)水泥土樁樁身完整性415根樁，檢測(cè)比例為30%均屬基本完整性樁。取s/b=（b為方形壓板的寬度）對(duì)應(yīng)的荷載，其值均超過最大加荷量的一半，因此取最大加荷量的一半作為夯實(shí)水泥土樁的單樁復(fù)合地基承載力設(shè)計(jì)值。是為了改善基礎(chǔ)與復(fù)合地基的接觸條件，以利于樁間土發(fā)揮承載作用。夯實(shí)水泥土樁復(fù)合地基的變形包括復(fù)合土層的壓縮變形S1和下臥層的壓縮變形S2，可采用分層總和法計(jì)算。目前關(guān)于負(fù)摩阻力的影響的看法還不一致，對(duì)于負(fù)摩阻力的計(jì)算僅有估算方法。對(duì)于一般而言，在垂直下壓荷載作用下，樁對(duì)于樁周土向下位移，這時(shí)樁周受到向上的摩阻力，稱為正摩阻力，也就是代入公式計(jì)算的摩阻力。當(dāng)采用425號(hào)礦渣硅酸鹽水泥，水泥摻入比為10%，由室內(nèi)加固土塊28天無側(cè)限抗壓強(qiáng)度平均值可推得=6Mpa?；诤粚?shí)水泥土樁樁身應(yīng)力的傳遞規(guī)律，其單樁承載力應(yīng)依據(jù)《建筑樁基技術(shù)規(guī)范》中樁基豎向承載力設(shè)計(jì)值和關(guān)于水泥土樁計(jì)算的有關(guān)資料確定。在有，夯實(shí)水泥土樁比較經(jīng)濟(jì)，據(jù)查閱資料及一些數(shù)據(jù)統(tǒng)計(jì)可知，用夯實(shí)水泥土樁比水泥粉煤灰碎石樁（CFG樁）節(jié)約造價(jià)約20%左右。在樁機(jī)就位后，取土成孔，選出好土在最優(yōu)含水量的前提下與定量的水泥拌合，通過離子交換和團(tuán)粒化作用等一系列反應(yīng)，吸收大量游離的空隙水，生成