深層攪拌樁論文：黃河三角洲咸水區(qū)水泥土深層攪拌樁復(fù)合地基承載與沉降特性研究

1、深層攪拌樁論文：黃河三角洲咸水區(qū)水泥土深層攪拌樁復(fù)合地基承載與沉降特性研究【中文摘要】黃河三角洲是年輕陸地,廣泛分布著以低液限粉土、含砂的亞粘土、粉砂土為主的沉積土,工程性質(zhì)差,有些地區(qū)甚至是欠固結(jié)土,為減小高填方路基等上部建筑物過大的不均勻沉降,往往采用水泥土深層攪拌樁對(duì)地基進(jìn)行加固,但黃河三角洲地區(qū)存在大面積地下咸水,地下水和土的礦化度都很高。前期研究已表明,咸水拌和水泥土的耐久性很差,由此會(huì)引起攪拌樁復(fù)合地基承載性能發(fā)生衰變,最終導(dǎo)致路基等上部建筑發(fā)生過大沉降(如橋頭跳車現(xiàn)象)或失穩(wěn)破壞,這將導(dǎo)致復(fù)合地基實(shí)際短壽命與道路等上部結(jié)構(gòu)設(shè)計(jì)長壽命不協(xié)調(diào)的現(xiàn)象,不僅帶來國有資產(chǎn)的浪費(fèi),而且產(chǎn)生很

2、壞的社會(huì)影響。本文在對(duì)黃河三角洲典型區(qū)域地下水質(zhì)和土力學(xué)性質(zhì)進(jìn)行調(diào)查和分析基礎(chǔ)上,利用試驗(yàn)和理論等綜合手段,對(duì)水泥土力學(xué)性能的衰變特性及其對(duì)復(fù)合地基整體承載性的影響等進(jìn)行了系統(tǒng)研究：1、以濱德高速公路k15+155.5-k15+205.5段作為試驗(yàn)段,對(duì)黃河三角洲咸水區(qū)土和水的特性進(jìn)行了調(diào)查與分析；2、基于室內(nèi)試驗(yàn),研究了黃河三角洲咸水區(qū)水泥土力學(xué)特性隨時(shí)間的變化規(guī)律,并與正常水泥土進(jìn)行了比較分析；3、為了研究黃河三角洲咸水區(qū)水泥土樁復(fù)合地基的沉降和承載特性,進(jìn)行了1：50的模型試驗(yàn)研究。研究發(fā)現(xiàn)水泥土劣化將使復(fù)合地基沉降明顯增大,復(fù)合地基承載性能降低；樁體缺陷將加快嚴(yán)酷地下咸水環(huán)境下的水泥土

3、劣化,進(jìn)而導(dǎo)致攪拌樁復(fù)合地基的沉降明顯增大,所以在黃河三角洲攪拌樁施工中更應(yīng)該嚴(yán)格控制施工質(zhì)量；適當(dāng)減小邊樁長度,工程成本明顯減小,但復(fù)合地基總體承載性能變化不大,在設(shè)計(jì)中值得推薦。本文為黃河三角洲咸水區(qū)復(fù)合地基的耐久性設(shè)計(jì)提供了理論支撐和技術(shù)指導(dǎo),具有重要的經(jīng)濟(jì)和社會(huì)意義。本文受到國家自然科學(xué)基金項(xiàng)目(51078222；50708056)和山東大學(xué)自主創(chuàng)新基金杰出青年培養(yǎng)項(xiàng)目(2010JQ001)的資助?！居⑽恼縏he Yellow River Delta is a new-formed land, with the wide distribution of the sedimentar

4、y soil mainly composed of low liquid limit powder soil, sand-contained sub-clay and silty soil, all of which above show poor engineering properties and even parts have developed the underconsolidated soils. To reduce the excessive uneven settlement brought by the upper buildings, for instance the hi

5、gh-fill subgrade, soil-cement deep mixing pile of foundation reinforcement is frequently adopted. However in the Yellow River Delta areas, there exists a large scale of salty water, groundwater and subsurface soil with high level of salinity. Previous research has shown that the durability of cement

6、-soil mixed with salt-water is poor, which may cause the bearing capacity of mixing pile composite foundation decay, and eventually lead to the excessive settlement of upper buildings such as roadbed (this settlement probably induce the phenomenon of bridge head bump) or instability and failure of c

7、omposite foundation. Those distresses will result in the uncoordinated phenomenon between the short life of the composite foundation and the long life of upper structure design, bringing in state-owned assets waste.This paper,based on the survey data on the quality of groundwater and the mechanical

8、properities of soils spreading around the Yellow River Delta regions systematically study the decay of cement-soil characteristics and its mechanical properties of composite foundation,exploring a comprehensive methods including test, theory numerical analysis and etc.1. This research chooses Binzho

9、u-Dezhou Highway K15+155.5K15+205.5 as the testing area to analyse the characteristics of soil and water of salt-water area in the Yellow River Delta.2. Based on the laboratory test, this paper studies the regulations over time on the soil-cement mechanics properties of salt water area in the Yellow

10、 River Delta, compared with the normal soil-cement, meanwhile.3. The model simulation test with the ratio of 1:50 was conducted to study the settlement and bearing capacity of cement pile composite foundation in the salt-water area of the Yellow River delta. And it was found that the cemen-soil degr

11、adation caused settlement increase obviously and bearing capacity of the composite foundation decay, then the design scheme taking the durability of cement-soil into account. In the meanwhile, pile defection will speed up cement-soil degradation in the salt-water area, leading to the settlement of t

12、he mixing composite foundation increases obviously, so its necessary to pay more attention to controlling construction quality in the Yellow River delta; At last, its wise to decrease the length of pile in the edge, for it can save the construction cost without affecting the composite foundation bea

13、ring capacity.Based on above fundementaly research, this study provided theoretical support and technical guidance on the the durability design of composite foundation. And it will gain vast economic benefit and social meaning.This work was supported by the Chinese Natural Science Foundations (Nos.5

14、1078222,50708056 and 50978207) and Independent Innovation Foundation of Shandong University, IIFSDU (No.2010JQ001).【關(guān)鍵詞】深層攪拌樁 黃河三角洲 咸水區(qū) 腐蝕 模型試驗(yàn)【英文關(guān)鍵詞】Deep mixed pile Yellow River Delta salt-water area corrosion model test【目錄】黃河三角洲咸水區(qū)水泥土深層攪拌樁復(fù)合地基承載與沉降特性研究摘要8-9ABSTRACT9-10第一章 緒論11-211.1 研究背景與意義11-121.

15、2 國內(nèi)外研究進(jìn)展與分析12-171.3 研究內(nèi)容17-181.4 創(chuàng)新點(diǎn)181.5 技術(shù)路線18-21第二章 黃河三角洲地下咸水區(qū)土水特性調(diào)查與分析21-272.1 黃河三角洲地下水的演化21-222.1.1 古黃河三角洲21-222.1.2 近代和現(xiàn)代黃河三角洲222.2 試驗(yàn)段土的化學(xué)特征分析22-252.2.1 取土樣位置22-232.2.2 土樣的易溶鹽含量試驗(yàn)23-242.2.3 土樣的定名及含鹽量分析24-252.3 地下咸水理化分析25-262.4 小結(jié)26-27第三章 黃河三角洲含鹽水泥土力學(xué)特性時(shí)變規(guī)律試驗(yàn)研究27-453.1 水泥土固化原理27-293.2 水泥土室內(nèi)試驗(yàn)29-453.2.1 試驗(yàn)?zāi)康?9-303.2.2 試驗(yàn)內(nèi)容303.2.3 試驗(yàn)方案303.2.4 試驗(yàn)準(zhǔn)備30-313.2.5 測試結(jié)果及分析31-433.2.6 小結(jié)43-45第四章 黃河三角洲咸水區(qū)水泥土樁復(fù)合地基模型試驗(yàn)研究45-674.1 模型試驗(yàn)基本原理45-484.1.1 量綱分析45-464.1.2 量綱分析的方法46-474.1.3 模型比尺47-484.2 試驗(yàn)方案48-494.3 模型箱研制49-514.4 樁體和復(fù)合地基模擬51-524.5 路堤荷載模擬方法52-534.6 模型試驗(yàn)過程及測試53-