Method Cement Post-grouting to Increase the Load Capacity for Bored Pile

Van Loc Nguyen,Min Zhang,Lei Nie

doi:10.19026/rjaset.5.4310

Abstract

Drilled shafts foundations are used as an indispensable solution for long span bridges in Vietnam. In order to increase the bearing capacity, aside from the increasing of the pile length and diameter, an interested way now is treatment of pile bases after concrete placement. This study is aimed at investigating the defect at the bottom of the bored pile from the sonic test. The injection of hight pressure of cement grout to the shaft and tip of the defected bored pile was conducted to increase the bearing capacity of pile. The bearing capacity of defected bored pile is calculated by the TCXD-205:1998 an finite element mothod. After post-grouting technique done, the soil investigation tests have been carried out to define the properties of treated soils. The analytic mothod, finite element method an load test also have been applied to determine the bearing capacity of treated bored pile. The results show that the post-grouting to the shaft and tip of pile can increase two times of bearing capacity of defected bored pile and about 20% compared to the normal bored pile.

Highlights

Nowadays construction demand is increasing, so the application of new technologies, including the construction of bored pile technology is an inevitable development to the construction industry
According to some experimental research, the bearing capacity around of bored pile can reach the maximum value at about 0.5-1% of the diameter D of the settlement, while the load capacity of bored pile only be mobilized fully reaching 10-15% of the diameter D of the settlement
The results show that the post – grouting to the shaft and tip of pile can increase two times of bearing capacity of defected bored pile and about 20% compared to the normal bored pile

Summary

INTRODUCTION

Nowadays construction demand is increasing, so the application of new technologies, including the construction of bored pile technology is an inevitable development to the construction industry. Further more thick humus deposited at the bottom of the pile tip contributed to this problem This greatly reduces the bearing capacity of bored pile. It needs to continue to conduct experiments to evaluate the increase load capacity of the pile bottom, due to the grouting to the soils as well as specific pressure pump, in order to improve the method of calculating the load capacity of pile handled by this technology. The injection of hight pressure of cement grout to the shaft and tip of the defected bored pile was conducted to increase the bearing capacity of pile. The results show that the post – grouting to the shaft and tip of pile can increase two times of bearing capacity of defected bored pile and about 20% compared to the normal bored pile

CAPACITY BORED PILE

Tight sand very thick

Applied load P

Findings

Pile after post grouting