Arch–gravity dams feature both arch action and large concrete volume, yet targeted research on temperature control and crack prevention for this type remains insufficient. To address this, a Two-Parameter Decision Chart Method for predicting allowable placing temperature, an Analytical–Numerical Hybrid Estimation Method for estimating cooling durations, and the Comprehensive Cracking Risk Index (CCRI) for assessing lifecycle concrete safety are proposed, forming a complete design methodology. A case study on a proposed project using full-process simulation quantitatively evaluates the contribution of various measures in mitigating thermal stress across dam zones. Results show that without measures, the CCRI values for interior and surface concrete reach 68.9% and 38.1%, respectively. After implementing combined optimization measures targeting the control of maximum temperature, final temperature before grouting, and internal–external temperature difference throughout the entire process, both CCRI values are reduced to zero. Contribution analysis reveals distinct zonal effectiveness: for interior concrete, low-temperature placement with first-stage cooling contributes most (59.9%); for surface concrete, second- and third-stage cooling dominates (72.7%). Therefore, in practical engineering applications for temperature control and crack prevention in arch–gravity dams, a combination of measures centered on controlling the maximum temperature, optimizing the cooling process, and enhancing surface insulation should be adopted based on the characteristics of interior and surface zones, thereby improving cracking safety.

Cemented granular materials (CGMs) represent a transitional class of geomaterials where mechanical behavior is governed by the interplay between a discrete granular skeleton and a continuous cementitious matrix. While previous studies have focused on idealized spherical particles, this study aims to quantify the influence of the cement filling ratio (ranging from 10% to 100%) on the mechanical constitutive behavior of CGMs fabricated with large, irregular granitic aggregates (14–20 mm). Unconfined compressive tests and splitting tensile tests were conducted to evaluate the evolution of strength, stiffness, and failure modes. The results reveal a distinct mechanical transition governed by the cement filling ratio (${\rho }_m$). The elastic modulus and splitting tensile strength exhibited a linear increase with ${\rho }_m$ (R2 > 0.95), indicating a direct dependence on the volume fraction of the binding phase. In contrast, the unconfined compressive strength (UCS) and peak strain displayed a bilinear growth pattern with a critical inflection point at ${\rho }_m$ = 80%. For the specific irregular granitic aggregate skeleton investigated, this threshold marks the transition from contact-dominated stability to matrix-dominated continuum behavior. Below this threshold, strength gain is limited by the stability of discrete particle contacts; above 80%, the material behaves as a continuum, with UCS increasing rapidly to a maximum of 41.78 MPa at 100% filling. Furthermore, the dispersion of stress–strain responses significantly decreased as ${\rho }_m$ exceeded 50%, attributed to the homogenization of stress distribution within the specimen. These findings provide a quantitative basis for optimizing cement usage in ground reinforcement applications, identifying 80% as a critical design threshold.