本文關(guān)鍵詞：非等長(zhǎng)雙排樁在成都膨脹土基坑工程中的應(yīng)用研究　出處：《成都理工大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 膨脹土基 坑非等長(zhǎng)雙排樁 計(jì)算分析 有限元分析 工程應(yīng)用

【摘要】：隨著成都地區(qū)深大基坑的增多,施工場(chǎng)地小及紅線距離近等問(wèn)題逐漸明顯,對(duì)基坑變形的控制也提出了更高的要求。由于成都東郊膨脹土地區(qū)土層含有大量的高嶺土,遇水軟化后,錨桿、錨索桿件不能通過(guò)土體的側(cè)向摩擦力為基坑支護(hù)結(jié)構(gòu)提出足夠的錨固力,致使該地區(qū)的基坑常常出現(xiàn)垮塌的險(xiǎn)情,給人民的生命及財(cái)產(chǎn)安全造成巨大的影響。因此,如何解決好膨脹土地區(qū)城市建設(shè)項(xiàng)目中的基坑支護(hù)及環(huán)境效應(yīng)問(wèn)題成為巖土工程的熱點(diǎn)與難點(diǎn),技術(shù)安全、經(jīng)濟(jì)合理的基坑支護(hù)結(jié)構(gòu)體系是基坑工程的一個(gè)發(fā)展方向及研究重點(diǎn)。雙排樁支護(hù)結(jié)構(gòu)由于具有整體高度大、側(cè)向位移小、不需要設(shè)置支撐、施工方便、速度快、不需要工作面等優(yōu)點(diǎn),目前廣泛應(yīng)用于邊坡加固、邊坡抗滑、基坑支護(hù)等工程中。但是,雙排樁的作用機(jī)理及受力特性目前還不清楚,雙排樁的設(shè)計(jì)理論不成熟,主要依靠工程經(jīng)驗(yàn)。本文在總結(jié)前人研究的基礎(chǔ)上,以成都膨脹土地區(qū)東方華大廣場(chǎng)基坑工程為背景,對(duì)地基巖土體的物理力學(xué)參數(shù)特征進(jìn)行研究,并結(jié)合大型有限元分析軟件MIDAS-GTS對(duì)雙排樁支護(hù)結(jié)構(gòu)的受力性狀包括雙排樁的排拒、后排樁樁距、樁身剛度、嵌固深度、土體性質(zhì)和前后樁長(zhǎng)不等的情況進(jìn)行建模分析,研究雙排樁的最優(yōu)設(shè)計(jì)參數(shù),提出了非等長(zhǎng)雙排樁在成都膨脹土基坑工程中的應(yīng)用,最后以典型工程為例,對(duì)支護(hù)結(jié)構(gòu)進(jìn)行模擬計(jì)算,并結(jié)合監(jiān)測(cè)數(shù)據(jù)驗(yàn)證了方案的合理性,為非等長(zhǎng)雙排樁支護(hù)結(jié)構(gòu)在以后膨脹土基坑中的應(yīng)用提供工程經(jīng)驗(yàn),減少膨脹土地區(qū)工程造價(jià),并為進(jìn)一步的優(yōu)化設(shè)計(jì)提供理論支持。本文研究的主要成果有:(1)對(duì)研究區(qū)膨脹土的物理力學(xué)參數(shù)特征進(jìn)行研究發(fā)現(xiàn),未遇水軟化段土體強(qiáng)度是遇水段強(qiáng)度的2倍左右;膨脹土強(qiáng)度參數(shù)粘聚力c和含水率呈線性關(guān)系。(2)通過(guò)對(duì)雙排樁不同的排拒、后排樁樁距、樁身剛度、嵌固深度、土體性質(zhì)和前后樁長(zhǎng)不等的情況進(jìn)行建模分析發(fā)現(xiàn):(1)前后樁長(zhǎng)不等情況下,后排樁的樁長(zhǎng)變化比前排樁更能影響支護(hù)結(jié)構(gòu)的位移和內(nèi)力,且后排樁樁長(zhǎng)增加到一定值時(shí),對(duì)支護(hù)結(jié)構(gòu)的影響較小,此時(shí)的后排樁長(zhǎng)度為最優(yōu)長(zhǎng)度,能體現(xiàn)出該支護(hù)設(shè)計(jì)的經(jīng)濟(jì)性。(2)土層粘聚力對(duì)支護(hù)結(jié)構(gòu)的位移影響較大,內(nèi)力影響較小;內(nèi)摩擦角對(duì)支護(hù)結(jié)構(gòu)的位移和內(nèi)力都有較大影響。(3)排拒適當(dāng)增加,支護(hù)結(jié)構(gòu)的位移會(huì)減小,且隨著排拒的增大,位移的減小幅度在不斷減小,當(dāng)排距增加達(dá)到一定值以后,排距變化對(duì)支護(hù)結(jié)構(gòu)的位移影響較小,并且前排樁彎矩逐漸上升,后排樁彎矩則逐漸下降。(3)對(duì)成都東郊龍泉驛地區(qū)的工程實(shí)例進(jìn)行數(shù)值模擬分析,比較計(jì)算值與實(shí)測(cè)值二者之間的差異。同時(shí)根據(jù)樁身應(yīng)力、冠梁應(yīng)力及樁后土壓力的變化,分析膨脹土地區(qū)非等長(zhǎng)雙排樁支護(hù)結(jié)構(gòu)的受力形狀。為非等長(zhǎng)雙排樁支護(hù)結(jié)構(gòu)在以后膨脹土基坑中的應(yīng)用提供工程經(jīng)驗(yàn),并為進(jìn)一步的優(yōu)化設(shè)計(jì)提供理論支持,同時(shí)為該地區(qū)同類基坑工程支護(hù)設(shè)計(jì)提供借鑒。
[Abstract]:With the increase of the deep foundation pit in Chengdu area, small construction site and the red line near the problem gradually, also put forward higher requirements to control the deformation of foundation pit. Due to the eastern suburbs of Chengdu expansive soil area the soil contains a large amount of kaolin, water softening, bolt, anchor rod not by lateral friction of soil for foundation pit the supporting structure of anchoring force enough, resulting in the area of the foundation pit often collapse danger, causing huge influence to people's life and property security. Therefore, how to solve the city construction projects in the area of soil excavation and environmental effect of expansion has become the focus and difficulty of geotechnical engineering technology, safety, economy the reasonable foundation pit support structure system is a key development direction of foundation pit engineering and research of double row pile retaining structure as a whole big height, the lateral displacement is small, do not need to. The support, construction is convenient, fast, no need to face and other advantages, is widely used in slope reinforcement, landslide, engineering foundation pit supporting. However, the mechanism of double row pile and stress characteristic is unclear, the design theory of double row piles is not mature, depend on engineering experience. In this paper, on the basis of previous studies, using Chengdu expansive soil foundation pit engineering large square east China as the background, study the characteristics of physical and mechanical parameters of rock soil, and combined with the finite element analysis software MIDAS-GTS on the double row piles supporting structure stress characters including double row piles and rejection of the rear pile spacing. The pile stiffness, embedded depth, and soil properties before and after pile length ranging from the modeling analysis, the optimal design parameters of double row pile, put forward the non isometric double row piles in Chengdu expansive soil foundation pit engineering application, and finally to A typical project as an example, to simulate the supporting structure, and combining with the monitoring data to verify the rationality and non isometric double row piles supporting structure in the foundation pit after the expansion application provides engineering experience, reduce the area of expansive soil engineering cost, and provides theoretical support for the optimization design of the main results of this paper further. Study: (1) the study area expansion characteristics of soil physical and mechanical parameters were found in water softening water soil strength is about 2 times the strength of expansive soil; strength parameters cohesion c and moisture content showed a linear relationship. (2) based on the double row piles different rejection. The rear pile spacing, pile rigidity, embedded depth, and soil properties before and after pile length ranging from the modeling analysis found that: (1) before and after pile length ranging from under the condition of back pile length changes than the front pile can influence the displacement of supporting structure and internal Force, and the rear pile length increases to a certain value, the effect of supporting structure is small, the length of back row pile for the time optimal length, can reflect the supporting design of economy. (2) soil cohesion larger influence on displacement of supporting structure, the internal force influence is small; the internal friction angle of displacement and the internal force of supporting structure are affected. (3) rejection increased appropriately, the displacement of supporting structure will decrease, and with the increasing of rejection, the decrease in displacement decreases when the row spacing increase reaches a certain value, the row spacing changes on the supporting structure of the displacement effect the front and rear pile bending moment increased gradually, the pile bending moment decreased gradually. (3) based on the numerical simulation of the eastern suburbs of Chengdu Longquanyi area project, compare the difference between the two calculated values and measured values. At the same time according to the change of pile stress, stress and soil pressure of pile cap beam, divided Non isometric double row piles supporting structure stress analysis for land area expansion. The shape of unequal length double row piles supporting structure in the foundation pit after the expansion application provides engineering experience, and provide theoretical support for further optimization design, and provide reference for the design of similar foundation pit support in this area.

【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TU753

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