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Journal of Zhejiang University SCIENCE A

ISSN 1673-565X(Print), 1862-1775(Online), Monthly

Field studies of a technique to mitigate ground settlement of operating highways

Abstract: In the eastern coastal region of China, many operating highways built over soft ground are vulnerable to severe post-construction settlement. In this study, a technique using jet grouted piles is developed to mitigate post-construction settlement. The piles are installed by drilling boreholes throughout the embankment. The principal stages of the construction process are described, and two field tests in China, on the Lianyan and Linhai highways, are presented. The results revealed that ground heaves of up to 219 mm and 337 mm induced during a short construction period were able to mitigate the settlement of the embankment. The average settling rate was significantly reduced from 60 mm/y to 9 mm/y on the Lianyan highway. Lateral ground displacement on the Linhai highway increased with time during construction, but after construction showed a slight reduction associated with the dissipation of excess pore water pressure. An analytical method was adopted to describe the ground heave due to the jet grouted piles. The ground heave increased with grout pump pressure, but decreased as the embankment load and distance from the pile center increased.

Key words: Operating highway, Post-construction settlement, Jet grouted pile, Ground heave

Chinese Summary  <22> 既有高速公路沉降处治技术现场试验研究

目的:集成路堤竖向小直径引孔高压旋喷桩技术的施工工艺,分析其对既有高速公路沉降病害的处治效果,研究路堤在施工过程中的变形特性。
创新点:提出路堤竖向小直径引孔高压旋喷桩技术,并通过现场试验和理论研究分析其对既有高速公路沉降的处治效果。
方法:1. 通过两组现场试验,对处治前后路堤竖向变形(图6~8)、地基内超孔隙水压力(图10)和深层土体水平位移(图11)的变化特性进行分析与研究;2. 引用Wu et al. (2016)的理论解答(公式1)构建单桩引起的路堤隆起变形与路堤荷载和注浆压力之间的关系,为工艺参数调节提供依据,并利用实测数据加以验证。
结论:1. 竖向小直径引孔高压旋喷桩技术能够在较短的时间内抬升路堤和加固地基,从而有效降低既有高速公路的工后沉降速率,处治效果明显。2. 路堤隆起变形的大小主要与路堤荷载和注浆压力有关,且随着与桩中心距离的增大而减小;通过合理调节注浆压力可以防止路堤因隆起过大而发生破坏。3. 施工期内,高压旋喷会导致超孔隙水压力和深层土体水平位移显著增大;随后,超孔隙水压力逐渐消散,深层土体水平位移也发生一定的回弹。

关键词组:既有高速公路;工后沉降;旋喷桩;土体隆起


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DOI:

10.1631/jzus.A1600231

CLC number:

TU473.1

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On-line Access:

2016-07-05

Received:

2016-03-11

Revision Accepted:

2016-06-08

Crosschecked:

2016-06-14

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