A Novel Method for Testing the Effect of Base Post-Grouting of Super-Long Piles

Abstract

The base post-grouting technology is widely used in pile foundation engineering to improve its behavior. For super-long piles, due to the large compression of pile shaft, conventional static load tests cannot effectively test the effect of post-grouting at the pile base. This study introduced a novel method to test the effect of base post-grouting of three 88 m long piles. A total of three test piles were grouted at the bottom of the piles. The grouting amount of the No. 1 pile was 500 kg, the No. 2 pile was 250 kg, and the No. 3 pile was 0 kg. The transmitted wave method in the pile and dynamic penetration method were used in combination to quantitatively evaluate the effect of base post-grouting on the soil below the pile base. The influencing range of base post-grouting was firstly evaluated by the transmitted wave method in the pile, and the strength of the soil before and after grouting under the same pile base was measured by the dynamic penetration method. The test results showed that: the depth of the pile base reinforcement was 2 m for No. 1 pile, and 1 m for No. 2 pile, which was consistent with the grouting amount; the elastic modulus of the soil below the pile base after base post-grouting was about twice that of the soil before base post-grouting; the strength of the soil below pile base was largely improved after grouting; and the bearing capacity of the base soil layer increased from 35.5% to 41.7% when the grouting amount increased from 250 kg to 500 kg.

Study on the Diffusion Parameters of Newtonian Fluid in High-Pressure Jet Disturbance Grouting

“…With reinforcement by grouting, the resistance to the pile top load significantly increases [3], and the ultimate bearing capacity can rise by over 40% [4]. The study [5] indicated that the soil strength below the pile base substantially improved following grouting. And research on the reinforcement effect of high-pressure jet grouting has attracted the attention of scholars.…”

Experimental Study on Post-Grouting Pile Vertical Bearing Performance Considering Different Grouting Methods and Parameters in Cohesive Soil

“…Cast-in-place bored pile foundations are extensively utilized in the construction of high-rise buildings, highways, and large-span bridges due to their numerous advantages, including simplified construction process, minimal noise, adaptability to different soil layers, flexible selection of length-diameter ratio, and high load-bearing capacity [1][2][3][4]. However, during construction, sedimentation on the pile bottom and the formation of slurry cake can have adverse effects on the bearing capacity of bored piles.…”

“…Since its initial application to bridge pier pile foundations in the last century [13], post-grouting technology has been subject to extensive research in the field of pile foundations. These studies have focused on several key aspects: (1) grouting technology research, which constituted a significant research direction in the early stages. This line of inquiry encompassed investigations into various aspects, such as different grouting positions, grouting devices, and grouting methods [14][15][16].…”