地下室改建深基礎施工模式之探討

近年來因都會區土地資源日漸稀少，想要找到素地構築新建築物著實不易，老舊的都市建築，設備機能也漸漸無法滿足現代需求，都市更新成為未來都會區建築的主流。在都市更新的過程中，部分個案因存在舊有地下室，並緊貼鄰房或道路，在拆除舊地下室及構築更深的新地下室時，若因規劃不慎，施工過程往往造成損鄰事件。由於舊地下室改建的複雜性很高，如何安全的拆除舊地下室，如何結合舊基礎，施築連續壁的深導溝，便成為最重要的課題。本研究蒐集、整理了十個相關案例，並將各案例依照新舊擋土牆的相對位置分為（1）新連續壁於舊擋土壁內側、（2）新連續壁與舊擋土壁交叉、（3）新連續壁取代舊擋土壁（4）新連續壁於舊擋土壁外側四大類。各案例皆建立新舊建物基本資料表、套繪新舊擋土設施平面圖、地質改良範圍，並將土層分布、地下水位、新舊地下室深度的剖面圖加以套繪，然後進一步的繪出施工步驟的示意圖，再輔以施工照片說明，並繪製四種形式的標準施工流程。然而，如何拆除舊地下室而不損鄰，必須考慮地盤種類與性質、地下水位高低、鄰房最近距離、鄰房基礎型式、與舊地下室基礎型式等因素進行規劃與設計，盡量利用舊有牆梁柱系統，借力使力來抵擋外側土水壓力，保持良好的施工動線，安全的拆除舊地下室，並完成土方回填，使基地恢復為素地，完成新連續壁導溝的假設工程。

關鍵字

都市更新；深導溝；隔艙；臨時撐牆；舊基礎拆除；點井降水；切削套管

並列摘要

The facility and function of existing aged buildings can no longer meet the mordern needs of people who reside in. Meanwhile it is getting difficult to find open land to construct a new building in metropolitan area due to the shortage of land resources. Therefore reconstruction of existing buildings will be a main source for urban renewal process. But how to replace the old basement with a deeper new basement without endanger the adjacent buildings is a great concerns for designers and general contractors. In this thesis, ten cases of basement renewal are studied, and are classified into four categories. ( 1 ) the new diaphragm wall is located inside of the existing retaining wall, ( 2 ) the new diaphragm wall crosses the existing retaining wall, ( 3 ) the new diaphragm wall replace the old wall ( 4 ) the new diaphragm wall is located outside of the existing retaining wall. A data base about old and new buildings, soil profiles, groundwater level, and old and new mat foundation levels is established for each case. In which, the reconstruction process of existing basement is studies in details. At the end, a standard reconstruction procedure of how to tear down old basement and maintain the ability to resist earth and groundwater pressures during basement renovation for each category is proposed.