【摘要】：隨著地鐵明挖公路隧道及高層建筑的大規(guī)模興起，我國出現(xiàn)了越來越多的基坑工程基坑工程涉及巖土和結構工程，大多情況下，又屬于臨時工程，基坑工程的安全性成為基坑設計者和施工者關注的重點針對地鐵及高層建筑的深基坑，國內(nèi)已積累了較為豐富的工程設計經(jīng)驗和相對成熟的結構計算方法，，并將之應用于明挖公路隧道基坑工程的設計然而，明挖公路隧道基坑深度大多在13米以下，較地鐵及高層建筑基坑淺得多，僅依靠以往工程設計經(jīng)驗是偏保守的片面的本文圍繞明挖公路隧道基坑工程的特點，對工程中常用的單排樁鋼板樁以及連續(xù)墻等支護結構進行結構驗算，分析其在不同基坑深度和不同地質(zhì)工況下的支護結構的工作性能，以期豐富明挖公路隧道基坑工程設計經(jīng)驗有效改進其施工工藝 首先，研究了適用于公路隧道基坑工程支護結構設計與分析方法，包括支護結構的破壞模式支護結構的基本假定和計算方法，為基坑開挖過程數(shù)值模擬提供研究基礎 其次，根據(jù)基坑工程支護結構的計算原理，建立支護桿系有限元模型，進行基坑開挖過程中支護結構的內(nèi)力及位移計算，討論地質(zhì)條件橫向支撐間距橫向支撐道數(shù)放坡高度等對支護結構的影響規(guī)律，結合工程實際需要，對施工工藝進行改進以便縮短施工工期 最后，對明挖公路隧道開挖深度最大的泵房原支護方案即單排樁與多道水平橫向支撐支護方案進行改進，提出一種新的支護方案——采用工廠預制的鋼板樁與雙拼工字鋼作為斜向支撐的支護方案，施工速度快，機械化程度高，并還對其進行結構驗算 通過研究發(fā)現(xiàn)：單排樁支護結構的穩(wěn)定性受橫向支撐的布置和樁的嵌固深度影響較為明顯，連續(xù)墻支護結構穩(wěn)定性受嵌固深度影響較為明顯，但受橫向支撐的間距變化相對較小；對此提出了典型的施工改進工藝泵房基坑支護改進方案中，結構內(nèi)力值與原設計方案基本相同，開挖過程中水平位移較小，對基坑周圍地表沉降及建筑物的影響小，由于取消了立柱，保證了足夠的施工機械和主體結構人工鋼筋綁扎作業(yè)空間，有利于縮短施工工期
[Abstract]:With the large-scale rise of subway open-cut highway tunnel and high-rise buildings, more and more foundation pit projects in China are involved in geotechnical and structural engineering, in most cases, they are also temporary works. The safety of foundation pit engineering has become the focus of foundation pit designers and builders for the deep foundation pit of subway and high-rise buildings, and has accumulated rich engineering design experience and relatively mature structural calculation methods in China. However, most of the excavation depth of open-cut highway tunnel is less than 13 meters, which is much shallower than that of subway and high-rise building foundation pit. Only relying on the previous engineering design experience is a conservative one-sided, this paper focuses on the characteristics of open-cut highway tunnel foundation pit engineering, carries on the structural checking calculation to the single-row pile steel plate pile and the continuous wall and other supporting structures commonly used in the project. The working performance of supporting structure under different depth of foundation pit and different geological conditions is analyzed in order to enrich the design experience of open-cut highway tunnel foundation pit and improve its construction technology first of all. This paper studies the design and analysis method of supporting structure suitable for highway tunnel foundation pit engineering, including the basic assumption and calculation method of supporting structure with failure mode, which provides the research foundation for numerical simulation of foundation pit excavation process. According to the calculation principle of supporting structure in foundation pit engineering, the finite element model of supporting rod system is established to calculate the internal force and displacement of supporting structure in the process of foundation pit excavation. This paper discusses the influence of the number of lateral bracing paths on the supporting structure in geological conditions. In combination with the practical needs of the engineering, the construction technology is improved in order to shorten the construction period. The original supporting scheme of pump house with the largest excavation depth of open-cut highway tunnel is improved, that is, single row pile and multi-track horizontal lateral supporting scheme. A new supporting scheme is put forward, which adopts prefabricated steel sheet pile and double-jointed I-shaped steel in factory as inclined bracing scheme, which has the advantages of fast construction speed and high mechanization degree. It is also found that the stability of single row pile supporting structure is affected by the arrangement of lateral bracing and the depth of pile fixation, and the stability of continuous wall retaining structure is influenced by the embedded depth of retaining structure, and the stability of single row pile retaining structure is influenced by the depth of embedding. However, the spacing of the lateral brace is relatively small. In this paper, a typical improvement scheme for foundation pit support of pump house is put forward. The internal force of the structure is basically the same as that of the original design, and the horizontal displacement is small in the excavation process, and the influence on the settlement of the ground around the foundation pit and the building is small. Because the post is cancelled, enough construction machinery and main structure artificial reinforcement binding working space is guaranteed, which is helpful to shorten the construction period.
【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U455.4;U452.11

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