Static and Dynamic Load Tests of Shaft and Base Grouted Concrete Piles

Abstract

is paper examines shaft and base grouted concrete piles by conducting vertical static load tests (SLTs) and dynamic load tests. ree concrete piles with shaft and base grouting, with base grouting only, and without grouting techniques were selected, and compressive SLTs were conducted. Two piles with grouting were also assessed with dynamic load tests. Another two uplift SLTs were conducted to one shaft and base grouted pile and one pile without grouting. Traditional presentations were provided to check whether the bored piles reached the design requirement. Interpretations of test results were also provided to determine the ultimate pile capacity. Results from these 5 SLT programs indicated that double-tangent and DeBeer's methods are close to each other, and Chin's method overestimates the pile capacity. Comparison of the results from the SLTs and dynamic load tests shows that the results from Chin's method are close to dynamic results, and Mazurkiewicz's method overestimates for friction resistance. e results also demonstrate that base and shaft grouted pile and base grouted pile increase by 9.82% and 2.89% in compressive capacity, respectively, and compared to the uplift SLTs; there is a 15.7% increment in pile capacity after using base and shaft grouting technology.

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

“…Assuming the soil has semi-infinite, homogeneous, and isotropic mass and a linear stress-strain relationship, the vertical movement of soil when a uniform pressure q is applied can be obtained using equation (3). In terms of the shape of the loaded area, Knappett and Craig [16] recommended the value of influence factor (I s ) to be 0.79 for the circular shape area.…”

“…In terms of the shape of the loaded area, Knappett and Craig [16] recommended the value of influence factor (I s ) to be 0.79 for the circular shape area. e stress q from the pile base can be determined when the base area A being circular using equation (4). For the isotropic elastic material, the relationship between shear modulus and Young's modulus can be illustrated as in equation (5).…”

“…e mentioned problem referring to the decreasing bearing capacity caused by the admixture layer can be solved by applying the post-grouting technology. During this grouting process, cement admixture is pressured down and the slurry support layer is then forced out [3,4]. Grouting equipment comprises a flat jack system, which consists of grout delivery pipes connected to a steel plate with a rubber membrane, and a sleeve-port system, which consists of two to four U-tubes installed at the bottom of the pile.…”

Experiment on Improving Bearing Capacity of Pile Foundation in Loess Area by Postgrouting

“…As an effective measure to improve the bearing capacity, postgrouting technology at the pile end has been recognized and used widely [11,12]. Karimi et al [13,14] used a truncated cone container to model the pile to study the effect of grouting on pile density and soil improvement.…”