|Table of Contents|

Study on vertical bearing characteristics of composite post grouting cast-in-place pile at pile bottom(PDF)

《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

Issue:
2023年05期
Page:
192-205
Research Field:
岩土工程
Publishing date:

Info

Title:
Study on vertical bearing characteristics of composite post grouting cast-in-place pile at pile bottom
Author(s):
ZHANG Xiaohua1;  WANG Xu1; 2;  ZHOU Yalong1;  ZHANG Yanjie1;  JIANG Daijun1
(1. School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China; 2.National and Provincial Joint Engineering Laboratory of Road & Bridge Disaster Prevention and Control, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China)
Keywords:
cast-in-place pile;  post grouting at pile bottom;  numerical simulation;  bearing characteristics;  load transfer;  grouting pressure;  spherical expansion theory
PACS:
TU473
DOI:
10.19815/j.jace.2021.11035
Abstract:
In order to reduce settlement, solidify sediment and improve the bearing capacity of cast-in-place pile, a composite post grouting process at the pile bottom of cast-in-place pile was put out. The steel plate capsule installed at the bottom of pile was used to strengthen the soil around the pile end through the composite grouting method inside and outside the capsule(open-close-open). Based on the post grouting and static load test of cast-in-place pile in Xilingjing highway bridge project, the real-time response law of grouting pressure, grouting volume and pile top displacement in the process of post grouting was studied, and the bearing characteristics of composite post grouting pile at pile bottom were explored. The bearing characteristics of the composite post grouting cast-in-place pile at the pile bottom of the project were numerically simulated by ABAQUS software, and the effects of grouting volume and grouting strength on the bearing capacity were discussed. The results show that the three grouting volumes of open-close-open alternate grouting at pile bottom all reach the design value, the average grouting pressure in the stable period is about 4.4 MPa, and the cumulative displacement of the pile top is raised by 1.01 mm. The ultimate bearing capacity of composite post grouting pile is about 1.9 times higher than that of conventional pile. At the same time, in the range of about 2.5d(d is pile radius)above the pile end, the side friction of composite post grouting pile increases obviously, the average side resistance reaches 189.7 kPa, the side resistance enhancement coefficient is 3.45, and the side friction presents an “R” distribution. With the increase of grouting volume and grouting strength, the bearing capacity of pile foundation increases rapidly. After the diameter of pile end enlarged head is about 2.5 times of pile diameter and the elastic modulus of pile end enlarged head is about 50 times of that of foundation soil, the bearing capacity increases slightly.

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Last Update: 2023-09-01