Model Test Research on Deformation Effect of Double-Row Piles in Deep Foundation Excavation

Abstract

As a new form of foundation pit support, double-row piles had the characteristics of high rigidity and remarkable economic effect. The deformation effect of the double-row piles and single row pile was compared and studied under the influence of foundation pit excavation and overload conditions combining the model test with theoretical calculation, which was based on the second phase project of China Dinosaur Park in Jiangsu Province. The earth pressure tested increased linearly with depth approximately, which fitted in the Rankine earth pressure distribution. In general, earth pressure distribution of model test was consistent with which calculated by Technical specification building foundation excavations (JGJ120-2012). It was 0.7~1.2 times as large as the model values when passive earth pressure calculated in standard was reduced by 1/3, which conformed to the actual situation basically. The study found that the relationship between horizontal displacement of pile top and time was basically consistent with the exponential function distribution. According to the time of convergence, the convergencing time of double-row piles was about 4h, and the convergencing time of single row pile was about 6h. The horizontal displacements in top of single row pile and inclined pile were 139% smaller than double-row piles. Main Influencing zone of deformation expanded to the pit and spreaded to deeper layers of soil as the increase of excavation depth and loading. Affected area of soil settlement behind pit spreaded to deeper layers of soil and backwards. The influence area of soil settlement after double-row piles was 0.8 times that of single row pile during excavation and loading.