A method for predicting mechanical behaviour of HPJG-Anchors – Part II: Prediction procedure, verifications and parametric studies

A new type of anchorage structure, anchor with an underreamed-segment formed by High Pressure Jet Grouting (HPJG-Anchor), has been extensively used in practice for the anti-floating of underground structures, support of foundation pits and protection of slopes. However, its load–displacement behaviour is seldom researched and not well-understood. Based on the load transfer models pre-proposed in a companion paper, a nonlinear load-transfer method is developed to predict the load–displacement behaviour of HPJG-Anchors, and the specific calculation procedure is also presented. This proposed method is then validated by comparing the calculated results with the field test data, and it is proved that the proposed prediction procedure is capable of providing rational estimation provided that the soil parameters are reliably determined. Afterwards, a series of parametric studies is carried out. The results indicate: the length of the free-stress segment is of an optimal value corresponding to the most efficient displacement control effect; an excessively strengthened free-stress segment will lead to obvious increase of construction cost but little increase of displacement control effect; bearing capacity of an HPJG-Anchor increases nonlinearly with the soil frictional angle and approximately linearly with the soil cohesion and shear modulus.