軟基論文：軟土地基處理施工引起的災(zāi)變分析

1、軟基論文：軟土地基處理施工引起的災(zāi)變分析【中文摘要】軟土在外力干擾下，土的結(jié)構(gòu)破壞，剪切強(qiáng)度劇烈降低；外力干擾停止后，軟土隨時(shí)間的增長逐漸恢復(fù)結(jié)構(gòu)和強(qiáng)度，同時(shí)產(chǎn)生很大的附加沉降，軟土災(zāi)變的破壞性很大。因此分析軟土地基處理災(zāi)害機(jī)理,優(yōu)化軟土地基處理方案和施工工藝，避免軟土產(chǎn)生擾動(dòng)破壞,具有重要的意義。本文主要采用現(xiàn)場(chǎng)試驗(yàn)結(jié)合理論分析的方法對(duì)軟土災(zāi)變現(xiàn)象進(jìn)行討論，主要成果有：在攪拌樁施工現(xiàn)場(chǎng)對(duì)孔隙水壓力、側(cè)向土壓力監(jiān)測(cè)，結(jié)合沉降觀測(cè)和靜力觸探試驗(yàn)，揭示攪拌樁施工對(duì)樁周土的擾動(dòng)規(guī)律以及軟土地基受攪拌樁施工產(chǎn)生的強(qiáng)度觸變。打樁過程中土體超孔隙水壓力大于土壓力，是導(dǎo)致攪拌樁掉樁的重要原因;大孔隙結(jié)構(gòu)、土

2、顆粒間的薄弱膠結(jié)處以及軟土顆粒間的“短程電作用”是軟土觸變的內(nèi)在因素，并受到溫度、含鹽量、電荷和含水量等因素的影響；并采用結(jié)構(gòu)動(dòng)力學(xué)模型和多維虛內(nèi)鍵模型對(duì)軟土觸變過程進(jìn)行模擬。結(jié)合考慮注漿體積、壓力以及土層參數(shù)的攪拌樁擴(kuò)孔半徑公式,采用受剪圓孔擴(kuò)張模型預(yù)測(cè)超孔壓、土壓力以及側(cè)向位移；介紹三種基于應(yīng)力應(yīng)變指標(biāo)的災(zāi)變判別方法，對(duì)災(zāi)變等級(jí)進(jìn)行劃分。通過設(shè)置對(duì)比試驗(yàn)結(jié)合理論分析，從減小攪拌樁施工影響角度出發(fā)，提出了軟基處理方式、施工順序、速度和樁間距等優(yōu)化的建議?！居⑽恼縏hestructureandshearstrengthofsoftclayisdestroyedandreducedunder

3、exteriordisturbaneewhichmakessoilintofluidwithoutstrength.Thereisalotofadditionalsettlementoccurringduringtherecoveryprocessofthestructureandstrengthofsoftclaywithtime.Duetotheseriousdamageeffectofdisaster,researchonthecharacteristicofsoftclayaffectedbyfoundationtreatment,thedisastermechanismanalysi

4、soffoundationtreatmentandmeasurestoavoidthedestroyofsoftclayaremeaningful.Basedonfieldtestandtheoryanalysis,themainconclusionwereasfollowings:Thetestofporepressureandlateralearthpressure,staticconepenetrationtestandsettlementobservationduringsoftfoundationtreatmentprocesswereusedtoanalysisthestrengt

5、hthixotropicandthedegreeofthixotropiccausedbycementmixingpileconstruction.Themainreasonleadingtomixingpilesinkingisthatporewaterpressureislargerthantheearthpressureduringpiling.Largeporous,theweakbondbetweensoilparticlesandthe“short-rangepowereffect”betweensoilparticlesaretheinternalfactorsofthixotr

6、opic.Otherfactorssuchastemperature,saltconcentration,chargeandwatercontentalsoaffectthethixotropicofsoftclay.Thestructuraldynamicmodelandmulti-dimensionalvirtualmodelwereusedtosimulatetheprocessofsoftclaythixotropic.Combinedwiththeformulaofreamingradiusconsideringgroutingvolume,groutingpressureandso

7、ilparameter,thecircleshearexpansionmodelwasusedtopredicttheexcessporepressureandlateraldisplacement.Threejudgingmethodsbasedonstressandstrainwereintroducedtojudgethegradeofdisaster.Basedoncontrasttestresults,thesuitablemode,sequeneeandvelocityofconstruction,theappropriatepilespacingweresomeeffective

8、methodsforthepreventionofsoftclaydisaster.【關(guān)鍵詞】軟基災(zāi)變模型判別預(yù)防措施【英文關(guān)鍵詞】catastrophesoftclayfoundationmodeldiscriminationpreventivemeasures【目錄】軟土地基處理施工引起的災(zāi)變分析摘要5-6ABSTRACTS第一章概論10-191.1研究背景及其意義10-111.2研究現(xiàn)狀11-181.2.1土的觸變性11-121.2.2地基處理的擾動(dòng)效應(yīng)12-171.2.3地基處理的優(yōu)化措施17-181.3本文的主要內(nèi)容與章節(jié)安排18-19第二章軟基處理施工現(xiàn)場(chǎng)試驗(yàn)19-352.1測(cè)試內(nèi)容192.2測(cè)點(diǎn)布置及埋設(shè)19-222.3測(cè)試結(jié)果分析22-332.3.1孔隙水壓力22-272.3.2側(cè)向土壓力27-292.3.3靜力觸探試驗(yàn)29-3