本文選題：軟土地基 + 堆載預(yù)壓��； 參考：《武漢輕工大學(xué)》2013年碩士論文

【摘要】：在我國(guó)的廣大地區(qū)都分布著軟土，其具有天然含水率高、天然空隙比大、滲透系數(shù)小、壓縮系數(shù)高、抗剪強(qiáng)度低等特點(diǎn)。工程建設(shè)中經(jīng)常會(huì)遇到軟土地基，天然的軟土地基往往不能滿足建筑物對(duì)地基的承載能力越來(lái)越高的要求，一些軟弱地基或特殊土地基在完成地基處理之后才可使用。從上世紀(jì)五十年代國(guó)內(nèi)外開(kāi)始運(yùn)用堆載預(yù)壓的方法加固軟土地基，堆載預(yù)壓法可以說(shuō)是伴隨著土力學(xué)一起發(fā)展的。早期在提出了太沙基固結(jié)理論后，土力學(xué)發(fā)展史上迎來(lái)了一個(gè)重要里程碑時(shí)刻，此后就開(kāi)始廣泛的運(yùn)用在實(shí)際工程中。后來(lái)由于Biot固結(jié)理論的提出及計(jì)算機(jī)技術(shù)的快速發(fā)展，有限單元法等一些數(shù)值計(jì)算方法的引入，，使得堆載預(yù)壓加固軟土地基土的技術(shù)得到了很大的發(fā)展。 本文首先對(duì)堆載預(yù)壓法的相關(guān)內(nèi)容進(jìn)行了簡(jiǎn)單的介紹，并對(duì)太沙基、Biot固結(jié)理論以及在Biot固結(jié)理論中常用的幾種本構(gòu)模型進(jìn)行了回顧。 然后總結(jié)分析了三種主要的抗剪強(qiáng)度理論。并根據(jù)魏西克(Vesic)圓柱孔擴(kuò)張理論，將飽和軟黏土當(dāng)作一種Tresca彈塑性材料，參考擠土樁法在軟土中所產(chǎn)生的彈塑性擴(kuò)張應(yīng)力解答為例，分別根據(jù)擠土過(guò)程中在塑性區(qū)和彈性區(qū)不同的應(yīng)力解析表達(dá)式，推導(dǎo)得出擠土過(guò)后地基土的應(yīng)力增長(zhǎng)表達(dá)式，定量分析了擠土對(duì)地基土抗剪強(qiáng)度增長(zhǎng)的影響，考慮擠土效應(yīng)對(duì)地基穩(wěn)定性的影響并進(jìn)行了計(jì)算分析。 最后結(jié)合某工程中原料廠采用堆載預(yù)壓的方法對(duì)軟土地基加固進(jìn)行研究。堆載容易引起堆載范圍內(nèi)軟土較大的沉降和水平側(cè)移，從而改變了鄰近建筑物地基土體的應(yīng)力狀態(tài)，使鄰近建筑物地基發(fā)生破壞。文中對(duì)堆載預(yù)壓使可能會(huì)對(duì)鄰近堆取料機(jī)軌道地基產(chǎn)生破壞的問(wèn)題進(jìn)行分析和解決。運(yùn)用數(shù)值計(jì)算的方法模擬堆載預(yù)壓處理原料廠軟土地基的過(guò)程并進(jìn)行分析和計(jì)算，提出了設(shè)置應(yīng)力隔離樁的改進(jìn)方法對(duì)原設(shè)計(jì)進(jìn)行優(yōu)化。
[Abstract]:Soft soil is distributed in the vast areas of our country. It has the characteristics of high natural moisture content, large natural void ratio, small permeability coefficient, high compression coefficient and low shear strength. Soft soil foundation is often encountered in engineering construction. Natural soft soil foundation often can not meet the requirement of higher and higher bearing capacity of building. Some soft foundation or special soil foundation can be used only after the foundation treatment is completed. Since 1950s, the method of surcharge preloading has been used to reinforce soft soil foundation, and the surcharge preloading method can be said to be developed along with soil mechanics. After putting forward the theory of Terzaghi consolidation in the early stage, the history of soil mechanics ushered in an important milestone moment, and then it began to be widely used in practical engineering. Later, due to the development of Biot consolidation theory and the rapid development of computer technology, and the introduction of some numerical methods such as finite element method, the technology of surcharge preloading to reinforce soft soil foundation has been greatly developed. In this paper, the relative contents of surcharge preloading method are briefly introduced, and the consolidation theory and several constitutive models commonly used in Biot consolidation theory are reviewed. Then three main shear strength theories are summarized and analyzed. The saturated soft clay is regarded as a Tresca elastoplastic material according to the theory of Vesic's expansion of cylindrical holes, and the solution of the elastoplastic expansion stress produced by the compaction pile method in the soft soil is taken as an example. According to the different analytical expressions of stress in plastic zone and elastic zone during soil compaction, the stress growth expression of foundation soil after compaction is derived, and the influence of compaction on the increase of shear strength of foundation soil is analyzed quantitatively. The effect of compaction on the stability of foundation is considered and calculated. Finally, the reinforcement of soft soil foundation is studied by the method of surcharge preloading in a raw material factory. It is easy to cause large settlement and horizontal lateral displacement of soft soil in the range of heap-loading, thus changing the stress state of the foundation soil of adjacent buildings and causing damage to the foundation of adjacent buildings. This paper analyzes and resolves the problem that the pile load preloading may cause damage to the track foundation of the adjacent heap-extractor. The numerical method is used to simulate, analyze and calculate the process of surcharge preloading treatment of soft soil foundation in raw material plant, and an improved method of setting stress isolation pile is put forward to optimize the original design.
【學(xué)位授予單位】：武漢輕工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類(lèi)號(hào)】：TU472.33

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