本文關鍵詞： 軟土 深基坑工程 優(yōu)化設計 重力式水泥土墻 雙排樁　出處：《暨南大學》2013年碩士論文　論文類型：學位論文

【摘要】：南沙地區(qū)位于穗港澳的幾何中心，是廣州未來發(fā)展的核心地區(qū)。該地區(qū)多為海陸交互相的軟弱黏性土，，工程地質和水文地質條件都較為復雜。深厚淤泥或淤泥質軟土層已成為南沙地區(qū)基礎工程和基坑工程中尤為突出的難題。本文主要針對南沙地區(qū)軟土特性，緊密結合該地區(qū)工程實例，就基坑支護選型、基坑支護加固以及基坑支護優(yōu)化方面展開分析，并提出合理的軟土深基坑工程方案，為南沙地區(qū)同類工程提供參考，主要研究內(nèi)容與成果如下： 1.采用理正軟件計算分析了南沙某基坑頂部邊坡塌方原因，結果表明：（1）施工運土車輛產(chǎn)生的邊坡頂部超載大大降低了邊坡穩(wěn)定安全系數(shù)；（2）地面積水滲入邊坡表層土后，土體發(fā)生軟化，粘聚力降低，邊坡趨于不安全甚至失穩(wěn)狀態(tài)；（3）基坑土體超挖使支護結構整體穩(wěn)定安全系數(shù)降低，不滿足規(guī)范要求。 2.對基坑原重力式水泥土墻支護方案進行了優(yōu)化設計，結果表明：（1）增設兩排水泥土攪拌樁使水泥土墻寬度達4.15m時，支護結構整體穩(wěn)定安全系數(shù)達最大值為1.329；（2）提高水泥土墻嵌固深度至11.0m時，基坑各穩(wěn)定性安全系數(shù)更為均衡；（3）當被動區(qū)加固體厚度增大時，支護結構最大水平位移明顯減小，并在加固體厚度超過4m后趨于穩(wěn)定；（4）頂部邊坡放緩，卸除冗余土體可有效增強基坑支護穩(wěn)定性。 3.引入了雙排樁支護方案，并與重力式水泥土墻支護方案進行了對比，結果表明：（1）考慮被動區(qū)加固土影響時，雙排樁支護方案各穩(wěn)定性安全系數(shù)與重力式水泥土支護方案差別不大；（2）不考慮被動區(qū)加固土影響時，雙排樁支護方案的抗傾覆穩(wěn)定性、整體穩(wěn)定性均明顯優(yōu)于重力式水泥土墻支護方案，樁身水平位移、彎矩以及所產(chǎn)生的地表沉降量均遠小于重力式水泥土墻。
[Abstract]:Nansha is located in the geometric center of Guangzhou, Hong Kong and Macao, and is the core of Guangzhou's future development. The engineering geology and hydrogeological conditions are complicated. The deep silt or silt soft soil has become the most prominent problem in the foundation engineering and foundation pit engineering in Nansha area. This paper mainly focuses on the characteristics of soft soil in Nansha area. Based on the engineering examples in this area, the selection of foundation pit support, the reinforcement of foundation pit and the optimization of foundation pit support are analyzed, and a reasonable project of soft soil deep foundation pit is put forward, which provides a reference for similar projects in Nansha area. The main research contents and results are as follows:. 1. The causes of slope collapse at the top of a foundation pit in Nansha are calculated and analyzed with the help of leveling software. The results show that the overloading on the top of the slope produced by the construction vehicles greatly reduces the slope stability safety factor and the surface water seeps into the surface soil of the slope. The soil softens, the cohesive force decreases, the slope tends to be unsafe or even unstable. The soil overexcavation of the foundation pit reduces the overall stability safety factor of the supporting structure and does not meet the requirements of the code. 2. The optimization design of the original gravity cement-soil wall supporting scheme of foundation pit is carried out. The results show that when two drainage soil mixing piles are added, the width of the cement-soil wall reaches 4.15m. When the stability safety factor of the supporting structure reaches the maximum value of 1.329m) when the cement-soil wall depth is increased to 11.0m, the stability safety factor of the foundation pit is more balanced. (3) when the passive zone and the solid thickness increase, the maximum horizontal displacement of the supporting structure decreases obviously. When the thickness of solid is more than 4 m, the slope at the top of the slope tends to be stabilized, and the stability of foundation pit support can be effectively enhanced by removing the redundant soil. 3. The double row pile support scheme is introduced and compared with the gravity cement-soil wall support scheme. The results show that when considering the influence of the reinforced soil in the passive zone, When the stability safety factor of double-row pile support scheme is not different from gravity cement-soil support scheme, the overturning stability of double-row pile support scheme is not considered when the influence of passive zone reinforcement is not considered. The overall stability is obviously superior to that of gravity cement-soil wall, and the horizontal displacement, bending moment and surface settlement of the pile are much smaller than those of gravity cement soil wall.
【學位授予單位】：暨南大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU753;TU714

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