Field Static Load Tests of Post‐Grouted Piles under Various Failure Conditions

Abstract

In practice, inappropriate test set-up and design will result in pile eccentricity, reducing pile bearing capacity. Also, inappropriate piling will reduce the strength of the upper part of concrete. These pile elements under inappropriate design and construction are easy to be overlooked since they are invisible. Because the research focuses on the pile failure behaviour under different conditions, this paper aims to determine the outcomes of pile foundation under eccentric loading, pile with inadequate concrete strength, and pile with punching failure. Four concrete piles were cast, and compressive static load tests (SLTs) were performed. The top part of the first pile was cast with inadequate concrete strength. The other two piles were cast with achieved concrete strength; however, one of these applied with eccentric loading. The third pile was the standard pile, and the fourth pile was tested until punching failure occurred. For the fourth pile, the T-Z method was used for determining the failure characteristics. It is discovered that, for the pile with inadequate concrete strength, the cracks occurred at the pile head, and the concrete crushed at 0.9–1.2 m below the ground; for the pile suffering eccentricity, the partial concrete crushed, and the concrete from the opposite side suffered tension fracture; for the pile suffering punching failure, the crack on the soil extends up to 50 mm. Traditional result presentations and interpretations were also provided. Furthermore, it was found that, for the pile suffering punching failure, the shaft resistance increased as the loads increased, and after the loading achieved the maximum resistance, the loading transferred to the pile tip and finally led to the destruction of the pile-soil system.

The Analytical Solution of the Grouting Migration Height for the Post-Grouted Drilled Shaft Based on the Herschel-Bulkley Model

“…Subsequently, the PGDS has been gradually innovated and developed in the pile foundation engineering, mainly including the Gravel Basket Device [8], the High Pressure Bi-directional Loading Cells [9], the Sleeve Valve Tube Grouting Device [10], the Frustum Confining Vessel [11,12], the U-shaped Tube Grouting Device [13], the Punching and Binding Grouting Technology [14], and the Reserved Cavity Grouting with Movable Steel Plate [15]. Many researchers have carried out field or model tests to measure its bearing capacity of the PSDS [16][17][18]. Meanwhile, the reinforcing mechanism of the PGDS has been revealed, which mainly consists of the reinforcement effect of grouting material on soil at the pile tip [19][20][21], the enlargement of the pile tip [22,23], the reinforcement effect of grouting split along the pile shaft [24,25], and the negative friction of the pile shaft caused by grouting [26,27].…”