土釘墻+水泥土樁墻聯合支護結構的力學特性分析

萬宗江 朱碧堂

摘要：為充分發揮水泥土樁墻的高強度特性，提出了一種土釘墻+水泥土樁墻的基坑聯合支護結構，并介紹了其設計理念。基于有限元數值模型，結合南昌地區典型地質條件，系統地研究了聯合支護結構對滲流場、土體水平位移、土釘軸力、水泥土樁墻樁身應力、基坑破壞模式的影響，以及坑底加固、水泥土樁墻距離對基坑支護性能的影響，并與傳統土釘墻和復合土釘墻支護結構進行了對比分析。結果表明：在保證墻體安全的條件下，聯合支護結構的受力機制更合理，開挖面處土體水平位移、樁身軸向及切向應力均小于傳統的土釘墻和復合土釘墻;基坑破壞模式表現為重力式擋土墻破壞模式，對坑底進行加固處理可進一步顯著改善其支護性能。

關鍵詞：深基坑;水泥土樁墻;土釘墻;支護結構;數值模擬

中圖分類號：TU751 文獻標志碼：A 文章編號：20966717（2020）04001009

收稿日期：20200310

基金項目：國家自然科學基金（41972291）

作者簡介：萬宗江（1978 ），男，高級工程師，主要從事城市軌道、橋梁、隧道工程研究，Email：117905252@qq.com。

Received：20200310

Foundation items：National Natural Science Foundation of China （No. 41972291）

Author brief：Wan Zongjiang （1978 ）， senior engineer， main research interests： urban railway， bridge and tunnel engineering， Email： 117905252@qq.com.

Analysis of mechanical properties of a novel support structure with soil nailing wall combined with cemented soil pile/wall for deep excavation

Wan Zongjiang1，Zhu Bitang2

（1.China Railway No.2 Engineering Group Co. Ltd.， Chengdu 610031， P.R. China; 2.Engineering Research & Development Centre for Underground Technology of Jiangxi Province， Nanchang 330013， P. R. China）

Abstract：In order to fully utilize the high strength of the cemented soil pile/wall， a retaining structure with soil nailing wall combined with cemented soil pile/wall for deep excavation is proposed and its design philosophy is discussed in this paper. Based on finite element numerical simulation combined with the typical geological condition of Nanchang area， the distribution characteristics of seepage flow， horizontal soil displacement， axial force of soil nail， stress of cementsoil pile wall and the failure mode as well as the influence of bottom reinforcement and cementsoil pile wall distance of the novel structure on the support performance are systematically studied. Meanwhile， comparative analysis with the traditional soil nailing wall structure and the composite soil nailing wall structure are conducted. The results show that： Under the condition of ensuring the safety of the wall， the support mechanism of the novel structure is more reasonable due to the horizontal displacement of the soil at the excavation face and the axial and tangential stresses of cementsoil pile wall much smaller than that under the traditional soil nailing wall structure and the composite soil nailing wall structure; the failure mode of the foundation pit is similar with that under the gravity retaining wall support method， and reinforcement of the pit bottom can significantly improve its support performance.

Keywords：deep excavation; cement soil pile wall; soil nailing wall; supporting structure; numerical modelling

在富水砂層或中等強度黏土層的基坑支護設計中，水泥土樁墻（包括攪拌樁、高壓旋噴樁、等厚度水泥土墻TRD）通常用作止水帷幕以隔絕基坑內外的地下水連通，以便于基坑開挖施工[1]。事實上，除了隔水作用外，水泥土樁墻本身就具有優良的力學性能，其剛度和強度遠超天然土體。例如，李建軍等[2]基于室內模型試驗研究了粉土中不同水泥摻入比下水泥土強度及變形特性，試驗結果表明，24%水泥摻入比下，28 d無側限抗壓強度接近5 MPa，變形模量達到4.6 GPa。……