Abstract
A deep foundation pit in a station of the Hangzhou subway is adjacent to new high-rise residential buildings on the north side and to the Evergrande foundation pit being excavated on the south side. This work considers the excavation of the foundation pit in the subway station as the research subject, focuses on the difference of the deformation and Earth pressure between the north side and the south side of the foundation pit under these special working conditions through the analysis of the measured data, and compares it with an ordinary foundation pit. Analyzing the measured data reveals that the horizontal displacement of the retaining wall and the ground settlement are far larger on the north side than on the south side, and both often exceed the deformation alarm value; the deformation of the ordinary foundation pit is between the deformation of the overloaded (north) side and that of the unloaded (south) side of the foundation pit. Moreover, the maximum rate of the horizontal creep of the soil and the maximum rate of the creep caused by the ground settlement on the north side of the foundation pit are larger than those on the south side of the foundation pit; the maximum rate of the horizontal creep of the ordinary foundation pit is between the two. The active Earth pressure on the pit wall on the north side is higher than that on the south side of the foundation pit, and because of the surrounding unloading, passive Earth pressure is generated at the bottom of the pit wall on the south side of the foundation pit, which causes it to shift to the outside of the foundation pit. The settlement of the surrounding high-rise buildings and the settlement of the columns are all within the range of the alarm values; also, the buildings settle evenly. Due to the excavation and unloading on the south side of the foundation pit, the uplift of the columns is not considerable.
Highlights
During the municipal construction projects, foundation pit engineering is of great importance in the field of geotechnical engineering [1]. e enclosure system of a foundation pit has a small safety reserve, and the design and construction of the pit are closely related to the surrounding environment [2], which make the foundation pit engineering has its special characteristics such as high risk and individuality [3], especially for the excavation of deep foundation pits [4]
Owing to the high risk and high difficulty of the excavation process, deep foundation pits often pose great safety hazards to people such as the collapse of the deep foundation pit in the Xianghu station of the Hangzhou subway. erefore, monitoring and analysis of the excavation of deep foundation pits are of great significance for ensuring its safety [5]
Erefore, this paper considers the excavation of a deep foundation pit in a station of the Hangzhou subway as the subject of the study; the standard section of the foundation pit is close to the high-rise residential buildings on the north side and to the Evergrande pit being excavated on the south side. rough monitoring and analysis, the difference of the settlement and deformation characteristics between the two sides of the foundation pit under special conditions of overloading and unloading is examined; this deep foundation pit is compared with a common pit with neither overloading nor unloading on its periphery; the corresponding change law is derived, and the specific reasons for the difference between the two sides are summarized
Summary
During the municipal construction projects, foundation pit engineering is of great importance in the field of geotechnical engineering [1]. e enclosure system of a foundation pit has a small safety reserve, and the design and construction of the pit are closely related to the surrounding environment [2], which make the foundation pit engineering has its special characteristics such as high risk and individuality [3], especially for the excavation of deep foundation pits [4]. Erefore, this paper considers the excavation of a deep foundation pit in a station of the Hangzhou subway as the subject of the study; the standard section of the foundation pit is close to the high-rise residential buildings on the north side and to the Evergrande pit being excavated on the south side. The ground settlement on the north side are 2, 6, and 11 m from the north retaining wall in sequence. e distance between the measurement points of the ground settlement on the south side and the retaining wall of the foundation pit is 2 m. e horizontal displacement of the retaining wall can be analyzed by means of measurement points XY37, XY38, and XY39 on the north side and measurement points XY16, XY17, and XY18 on the south side
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