Analysis of vertically loaded jet-grout-pile-strengthened piles of expanded cross-section
RIS ID
127640
Abstract
Piles are often installed together with jet grouting - to form a jet-grout-pile-strengthened pile - in soft subsoil regions of China to increase bearing capacity and reduce project costs. To facilitate their design, this paper presents a load-transfer approach to model the non-linear behaviour of such piles with expanded cross-sections. Three interface models are introduced to describe the interactions between soil-cement, the core pile and natural soil. Force equilibrium and displacement compatibility expressions are established and implemented through a purposely designed spreadsheet. The approach was verified by loading tests on two well-instrumented piles. A parametric study shows that having one to three segments of thick soil-cement enables a 20-60% gain in bearing capacity and a 43-55% reduction in head settlement compared with the core pile itself, which is slightly affected by the soil-cement modulus and stiffness ratio. It is cost-effective in practice to adopt two to four segments of soil-cement with a thickness of 0·1 m to a radius of core pile, an ultimate compressive strength of the soil-cement of over 2 MPa and a stiffness ratio of over 100 to reduce settlement. Finally, a simple equation is proposed to estimate the ultimate bearing capacity of such piles, which was verified by loading tests on piles in three case histories.
Publication Details
Ren, L., Deng, Y. & Guo, W. (2018). Analysis of vertically loaded jet-grout-pile-strengthened piles of expanded cross-section. Proceedings of the Institution of Civil Engineers: Geotechnical Engineering, 171 (3), 252-266.