王敏+徐林榮
摘 要:為優化高速鐵路中等壓縮性土地基處理方案,依托贛龍高速鐵路試驗段,采用現場試驗及理論分析方法,研究了短樁網復合地基的變形特性,并與天然地基進行對比。結果表明:復合地基加固區沉降占總沉降的62%~75%;地基側向位移主要發生在預壓土堆載期,20 m深度范圍是主要的側向位移層,在相似條件下,復合地基與天然地基沉降主要發生的時間、主要的沉降土層厚度及路基橫斷面沉降差異較大。結果顯示了短樁網復合地基可有效控制中等壓縮性土地基變形。
關鍵詞:高速鐵路;中等壓縮性土;復合地基;天然地基;變形特性
中圖分類號:TU441.6
文獻標志碼:A 文章編號:1674-4764(2017)05-0063-08
Abstract:In order to optimize the processing scheme of medium compression soil foundation, the short pile-net composite foundation deformation characteristics is explored using the method of field test and theoretical analysis on a test section of Ganlong high-speed railway, and its compared with the natural foundation. It is shown that the settlement of composite foundation reinforced area is 62%~75% of total settlement, the lateral displacement mainly occurred in preloading soil loading period and 20m depth is the main layer. Under similar conditions, the main stage of settlement, the main settlement layer thickness and settlement of cross section are quite different between composite foundation and natural foundation. The results show that the short pile-net composite foundation can effectively control the deformation of the medium compression soil foundation, which can provide reference for similar projects.
Keywords: high-speed railway;medium compression soil;composite foundation;natural foundation;deformation characteristics
路基變形控制是確保列車安全、平順運行的前提條件[1-2],主要由兩部分組成:路基本體變形、地基變形,而地基變形是路基變形控制研究的重點[3]。同時,隨著列車運營的提速,地基變形控制的要求愈加嚴格,而對變形特性的深入了解是解決變形控制問題的重要前提,故變形特性的研究就成為工程設計中的主要問題之一[4]。
地基變形特性主要可歸納為空間特性和時間特性兩個方面??臻g特性主要包括路基橫斷面沉降差異[5]、加固區及下臥層差異[6-7]、樁土沉降差[8-9]等;在時間特性上,主要有各建設階段沉降值比較及沉降預測[10-11]等。在高速鐵路路基的勘察設計中,大量承載力在150 kPa以上的黏性土、粉土、砂類土、卵礫石類土大多屬于非飽和土范疇[12],壓縮性和滲透性比較復雜,其變形的時間及空間特性與飽和土有很大的不同[13]。……