The ground is shaken by thousands of earthquakes every year around the world. While most of them are small and low in magnitude and acceleration, a few could cause liquefaction even in gravelly soils, causing damage to several buildings and infrastructures. For example, earthquake-induced liquefaction, lateral spreading and ground deformation of gravelly soil in reclamation areas took place at Wellington's CentrePort during the 2016 Mw7.8 Kaikoura Earthquake, causing detrimental damage to the buildings and wharf (Cubrinovski et al. 2017). Worldwide, one of the issues that has continuously been brought to the attention of the engineering community is the lack of guidance for the characterisation and evaluation of gravelly soils (i.e. gravelly sands, sandy gravels, and uniform gravels). Such soils are often referred to as ‘problematic’ because their behaviour is still poorly understood. Due to the deficiency of well-documented case histories and the minimal availability of field assessment data, the current practice of evaluating the liquefaction resistance of gravelly soils relies on the assumption that liquefiable gravelly soil behaves like sandy ones (Abbaszadeh 2018). However, existing clean sand-based empirical correlations based on sands may not work to characterise gravelly soils and could be misleading engineering assessments. Therefore, research in studying the liquefaction mechanism and developing proper analysing techniques for gravelly soils is critical (not only in New Zealand) to characterise hazards presented by these materials so that engineers may effectively and economically minimise damage and loss caused by liquefaction of saturated gravelly soils. This study concentrated on the characterisation and critical assessment of the liquefaction potential of sand-gravel mixtures. In order to make recommendations for the use of suitable frameworks in practical applications, the objectives of this study were defined. The objectives of this study are (1) to characterise the selected sand–gravel mixtures (SGM) using the shear wave velocity method, (2.a) to identify a suitable physical and/or state parameter framework for the accurate liquefaction assessment of SGM using a cyclic stress approach, (2.b) to find the applicability of shear wave velocity-based liquefaction triggering curve developed for gravelly soil, and (2.c) to explore the applicability of energy based approach (EBM) for the liquefaction assessment of SGM. To achieve the objectives mentioned earlier, this study carried out a series of shear wave velocity and undrained cyclic triaxial tests on selected SGMs with different gravel content (GC) and relative density (Dr) were carried out. SGM were prepared by mixing a medium sand (New Brighton Sand), a coarse sand (Dalton River Washed Sand) and a commercially available round gravel (Gravel) having mean diameters of 0.2mm, 0.75mm and 5mm, respectively. Shear wave velocity (VS) of SGM specimens having gravel content (GC) 0, 10, 25, 40, 60, 80 and 100% with global relative density (Dr) 20, 30, 45 and 60% were measured at the mean effective stress (σ’) of 50, 100, 150 and 200 kPa. The laboratory results indicated that the VS of SGMs increases with increasing both the Dr and σ’, whereas the effect of GC would be marginal to significant depending on the limiting and threshold sand content. However, the intergrain state concept, equivalent void ratio (𝑒𝑓(𝑒𝑞)) and equivalent relative density (𝐷𝑟𝑓(𝑒𝑞)) are the suitable parameters to describe the VS of SGMs uniquely by combining the effects of GC and Dr. Further, the VS of SGM can be evaluated using a relation of equivalent void ratio and VS of clean sand with reasonable accuracy. In the second stage of this study, a series of stress-controlled undrained cyclic triaxial tests were conducted along with the measurement of VS on reconstituted SGM specimens with GC = 0, 10, 25 and 40%, and Dr ranging from 25 to 55%. The experimental results confirmed that both the GC and Dr have marginal to significant effects on the cyclic resistance ratio (CRR) of SGM, and highlighted the need to consider the GC and Dr effects together. In this regard, the use of the equivalent void ratio (𝑒𝑓(𝑒𝑞)) was found to be a suitable approach to describe the combined effect of GC and Dr on CRR as it provides a unique correlation for SGM. This study also compared the laboratory-based CRR- VS correlations with existing field-based liquefaction triggering curves developed based on clean sand and gravelly soil liquefaction case histories. The laboratory result is consistent with existing field-based curves for gravelly soils. The pore pressure generation and liquefaction resistance were then interpreted using an energy based method (EBM) of liquefaction assessment. It was shown that the rate of pore pressure development is influenced by the cyclic stress ratio (CSR), GC, and Dr of SGM depending on the GC and Dr conditions. However, a unique correlation exists between the pore pressure ratio and cumulative normalised dissipated energy during liquefaction. Further, the cumulative normalised energy was found to be a promising parameter to describe the CRR of gravelly soils for various strain levels, considering the integrated effect of GC and Dr on liquefaction resistance.