本文選題：深基坑 + 樁錨支護(hù)結(jié)構(gòu)　； 參考：《蘭州理工大學(xué)》2013年碩士論文

【摘要】：本文在對(duì)西北地區(qū)深基坑支護(hù)結(jié)構(gòu)設(shè)計(jì)研究現(xiàn)狀的基礎(chǔ)上,首先,以西寧火車站綜合改造基坑工程為例,對(duì)深基坑樁錨支護(hù)結(jié)構(gòu)優(yōu)化設(shè)計(jì)和基坑降水進(jìn)行了說明。其次,在該基坑中選擇3個(gè)典型樁錨支護(hù)單元,分別對(duì)懸臂排樁、單支點(diǎn)排樁和兩支點(diǎn)排樁在基坑開挖和樁頭側(cè)向加載、不同工況錨桿拉拔過程中樁的內(nèi)力和錨桿內(nèi)力進(jìn)行監(jiān)測(cè)。結(jié)果表明： (1)懸臂階段3根支護(hù)樁外側(cè)樁身應(yīng)力呈“拉—壓—拉”變化,內(nèi)側(cè)樁身應(yīng)力呈“壓—拉”變化,這與一般認(rèn)識(shí)不同。隨著基坑的開挖,同一測(cè)點(diǎn)鋼筋應(yīng)力逐漸增大,最大值位置略微下移,應(yīng)力零點(diǎn)出現(xiàn)的位置隨樁長(zhǎng)的不同而不同。 (2)單支點(diǎn)階段隨著基坑暴露時(shí)間的增加,外露樁身應(yīng)力增大,樁身鋼筋應(yīng)力峰值出現(xiàn)在開挖面附近區(qū)域,開挖面以下樁身應(yīng)力變化復(fù)雜,嵌固段應(yīng)力零點(diǎn)比懸臂階段出現(xiàn)的早。冠梁不僅能使支護(hù)樁的變形狀態(tài)不同于上端自由的直立桿件,而且可以有效減小樁身內(nèi)力。 (3)兩支點(diǎn)階段樁身鋼筋應(yīng)力變化趨于復(fù)雜,主要受基坑開挖時(shí)間和預(yù)應(yīng)力錨桿的張拉鎖定等因素的影響。 (4)錨桿拉拔至220kN時(shí),10.5m以上樁身外側(cè)鋼筋受拉,內(nèi)側(cè)受壓；12.0m以下內(nèi)外側(cè)鋼筋均受拉,其中16.0-18.0m以下樁身受力幾乎為零,說明支護(hù)樁長(zhǎng)可以適當(dāng)優(yōu)化。錨頭位移量為15-20mm,殘余變形約3mm。 (5)在此地層條件下,單懸臂樁頭內(nèi)側(cè)加載至210kN時(shí),樁頭位移達(dá)3.3cm,加載影響深度約8.0m；卸載至0kN時(shí),樁體存在殘余應(yīng)力。 (6)錨桿鎖定初期軸力減小量較大,隨著時(shí)間的增加錨桿軸力略有提高。隨著施工的進(jìn)行,最大軸力值沿桿體向底部位移,說明潛在滑裂面隨著錨桿預(yù)應(yīng)力發(fā)揮的程度逐步向錨桿尾部移動(dòng)；0-5.0m錨桿區(qū)段軸力降低約10%-15%,15m處基本為零,可以取為臨界長(zhǎng)度。 (7)對(duì)于兩道或兩道以上樁錨支護(hù),下一道錨桿預(yù)加荷載承擔(dān)了上一道錨桿原來抵抗的部分土壓力,使上一道錨桿自由段的軸力減小。可通過超張拉與改進(jìn)鎖定工藝和嚴(yán)格施工管理等手段來彌補(bǔ),使每根錨桿都發(fā)揮應(yīng)有的作用。 (8)桿體軸力和剪力不是平均分布的,與目前預(yù)應(yīng)力平均分布的假設(shè)和計(jì)算方法有一定出入。錨桿支護(hù)結(jié)構(gòu)不應(yīng)單純以其承載力作為設(shè)計(jì)標(biāo)準(zhǔn),而需考慮其最大允許變形量作為設(shè)計(jì)標(biāo)準(zhǔn)。 通過對(duì)現(xiàn)場(chǎng)試驗(yàn)成果的分析,準(zhǔn)確地掌握了基坑開挖過程支護(hù)結(jié)構(gòu)內(nèi)力演化規(guī)律,實(shí)現(xiàn)了信息化施工；同時(shí),為后續(xù)支護(hù)設(shè)計(jì)參數(shù)修改提供了依據(jù),指出了目前支擋結(jié)構(gòu)設(shè)計(jì)中存在的不足及進(jìn)一步研究的方向。
[Abstract]:Based on the research status of deep foundation pit support structure design in Northwest China, firstly, taking Xining railway station as an example, the optimization design and foundation pit dewatering of deep foundation pit pile and anchor support structure are explained.Secondly, three typical pile and anchor supporting units are selected in the foundation pit. The cantilever piles, single fulcrum piles and two fulcrum piles are loaded laterally in the excavation of the foundation pit and the pile head, respectively.The internal force of the pile and the internal force of the anchor rod are monitored during the drawing process of the anchor rod under different working conditions.The results show that:1) in the cantilever stage, the stress of the outside pile of three supporting piles is changed with "pull-compression-pull", and the stress of the inside pile is "pressure-tension", which is different from the general understanding.With the excavation of foundation pit, the stress of reinforcing bar at the same measuring point increases gradually, and the position of maximum value moves down slightly, and the position of stress zero is different with the length of pile.2) with the increase of foundation pit exposure time, the stress of exposed pile body increases in single fulcrum stage, and the peak stress of reinforcement appears in the area near the excavating surface. The stress change of pile body under excavating surface is complex, and the zero point of stress in fixed block is earlier than that in cantilever stage.The crown beam can not only make the deformation state of the supporting pile different from the vertical member with free upper end, but also effectively reduce the internal force of the pile body.3) the stress variation of reinforcement in pile body tends to be complex in two fulcrum stages, which is mainly affected by the excavation time of foundation pit and the tensioning and locking of prestressed anchor rod.4) when the anchor rod is pulled up to 220kN, the outside steel bar of the pile body above 10.5m is pulled, and the inner side steel bar below 12.0m is pulled, in which the force of the pile body below 16.0-18.0m is almost zero, which shows that the length of the supporting pile can be properly optimized.The displacement of the anchor head is 15-20 mm and the residual deformation is about 3 mm.5) under the condition of here layer, the displacement of pile head reaches 3.3 cm and the loading depth is about 8.0 m when the inside of single cantilever pile head is loaded to 210kN, and there is residual stress in pile body when unloading to 0kN.(6) the axial force decreases greatly at the initial locking stage, and increases slightly with the increase of time.With the development of the construction, the maximum axial force is shifted along the bottom of the bolt body, indicating that the potential slip surface moves gradually to the end of the anchor with the degree of prestressing force of anchor rod. The axial force of the Anchorage section of 0-5.0 m reduces by about 10 ~ 15m and is basically zero, and can be taken as the critical length.For two or more piles and anchors, the next anchor bearing part of the earth pressure of the previous anchor under preload, which reduces the axial force of the free section of the last anchor.It can be made up by means of overtension, improved locking technology and strict construction management, so that each anchor can play its due role.The axial force and shear force of the bar body are not evenly distributed, which is different from the assumption and calculation method of the average distribution of prestress at present.The bearing capacity of bolt supporting structure should not be taken as the design standard, but the maximum allowable deformation should be considered as the design standard.Through the analysis of the field test results, the evolution law of the internal force of the supporting structure during the excavation process of foundation pit is accurately grasped, and the information construction is realized, which provides the basis for the modification of the design parameters of the subsequent support.The deficiency and the direction of further research in the design of retaining structure are pointed out.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU473

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 王立明,高廣運(yùn),郭院成;單支點(diǎn)樁錨支護(hù)結(jié)構(gòu)的側(cè)移計(jì)算[J];地下空間與工程學(xué)報(bào);2005年04期

2 郭印;趙剛;孫元帝;郭勇夫;鮑召杰;李俊杰;謝芳;;樁錨式支護(hù)樁內(nèi)力和變形測(cè)試研究[J];地下空間與工程學(xué)報(bào);2009年05期

3 張欽喜;佟德凱;熊宗喜;郭麗菊;;亞奧廣場(chǎng)護(hù)坡樁內(nèi)力及錨桿拉力測(cè)試與分析[J];北京工業(yè)大學(xué)學(xué)報(bào);2006年02期

4 陳根全;錨桿樁的抗拔試驗(yàn)[J];工程勘察;1997年02期

5 段新勝,顧湘;懸臂式樁排支護(hù)結(jié)構(gòu)水平位移分析實(shí)例[J];工程勘察;1997年06期

6 周勇;朱彥鵬;;框架預(yù)應(yīng)力錨桿柔性支護(hù)結(jié)構(gòu)的錨桿預(yù)應(yīng)力損失研究[J];工程勘察;2010年09期

7 周勇;朱彥鵬;;蘭州地區(qū)深基坑支護(hù)技術(shù)探討[J];蘭州理工大學(xué)學(xué)報(bào);2007年05期

8 朱彥鵬,張安疆,王秀麗;m 法求解樁身內(nèi)力與變形的冪級(jí)數(shù)解[J];甘肅工業(yè)大學(xué)學(xué)報(bào);1997年03期

9 張尚根,趙佩勝;基坑開挖過程中支護(hù)結(jié)構(gòu)內(nèi)力及變形分析[J];工業(yè)建筑;2000年03期

10 王春波;袁洪升;;排樁支護(hù)內(nèi)力試驗(yàn)研究[J];河北工程大學(xué)學(xué)報(bào)(自然科學(xué)版);2009年01期

相關(guān)碩士學(xué)位論文 前1條

1 溫兆東;成都地鐵車站基坑支護(hù)結(jié)構(gòu)受力變形研究[D];西南交通大學(xué);2009年

，

本文編號(hào)：1752312