Developed by the Japan Chemical Grouting Association in 1986, high-pressure jet grouting is a process of mixing in situ soil with a high-pressure grout stream and is used as a foundation treatment. HPJG modifies the soil characteristics, creating jet grouting columns that increase the bearing capacity of the existing soil. While many foundational field tests exist, there are few studies on JGC composite foundations. Yan-ning Wang, Hao-ran Qin, and Lin-Shuang Zhao, present a case study of columns using HPJG, specifically for the work done on the Hong Kong–Zhuhai–Macao Bridge.
Their paper, “Full-Scale Loading Test of Jet Grouting in the Artificial Island–Immersed Tunnel Transition Area of the Hong Kong–Zhuhai–Macau Sea Link” in the International Journal of Geomechanics, focuses on the ground improvement of the transition area between the artificial island and immersed tunnel. The authors explore the preloading method to understand the additional stresses generated by an immersed tunnel, as well as popular methods to simulate settlement. Learn more about the findings at https://doi.org/10.1061/(ASCE)GM.1943-5622.0002625. The abstract is below.
Abstract
In the Hong Kong–Zhuhai–Macau Bridge mega project, several ground treatment methods were applied in the transition area between the artificial island and immersed tube tunnels to reduce the potential uneven foundation settlement underlying the tunnel, as the backfilled sand layer is more than 10 m around it. One of the foundation improvement methods involves the combination of preload and high-pressure jet grouting (HPJG) columns. Current field tests, such as core bowling, standard penetration test, and plate loading test, are not suitable for evaluating the strength of this reinforced foundation. This study presents a full-scale load test to examine the construction quality and effects of an HPJG-reinforced foundation. A novel method was designed based on the Boussinesq equation to simulate the additional stress distribution from the immersed tube tunnel. The tangent modulus method considering the impact of modulus nonlinearity was employed to calculate the nonlinear settlement of the treated foundation. Preferable settlement results were obtained using a set of pre-embedded high-precision hydrostatic leveling systems. Both the measured data and calculated settlement demonstrate the reasonableness of the present in situ test.
Delve into the test results in the ASCE Library: https://doi.org/10.1061/(ASCE)GM.1943-5622.0002625.
