Rock-filled concrete (RFC) is a dam construction technique that heavily relies on engineering machinery. Because of the conservative design concept, currently, many transverse joints exist in RFC gravity dams, resulting in a narrow working space and a small radius for mechanical rotation. The Dagutai RFC gravity dam innovatively adopts a design with fewer joints, and it has the longest section (134 m) among all RFC gravity dams. The reservoir has been in operation for more than 3 years after its impoundment. To determine the safety state of the Dagutai gravity dam during the impoundment operation period, this paper researched the dam's working behavior under different loads, using dam temperature, seepage pressure, and displacement monitoring results, along with the temperature stress simulation of the finite element method (FEM). The results revealed that the dam body's temperature and seepage pressure are within normal limits, and the dam's longest section has no obvious cracking or seepage, indicating that the dam performed well during storage and operation. RFC's adiabatic temperature rise is low, as evidenced by the temperature rise of the most unfavorable position in the long section being less than 10℃. The section length of the RFC gravity dam can be appropriately extended, but the large lifting surfaces near the foundation should not be constructed during hot seasons, to control the initial temperature and reduce temperature stress during construction. Compared to standard dam sections, the long section's stress state meets the requirements, and the maximum stress can reach 2.5 MPa under empty or full reservoir conditions. Reinforcing mesh and short joints should be installed in the upstream impermeable layer. Overwintering in the upstream surface above water and the downstream surface can cause high tensile stress. If a gravity RFC dam with no joints is built, the large tensile stress at both ends of the dam should be considered. Even when the overloading factor is 10.0, there was no yield failure through the upstream and downstream of the dam, indicating that the overloading safety of the dam is high and the dam stability is good. This paper's research can provide scientific guidance for the structure design of RFC gravity dams in the future.

Key thermal parameters of self-compacting, rock-filled, and normal concrete of the rock-filled concrete gravity dam of Shibahe Reservoir in Renhuai City, Guizhou Province, are inverted based on its design data and temperature-monitoring data. On this basis, the finite element simulation method is used to simulate the working behavior during the construction of the dam, including the dam pouring, concrete hardening, and meteorological change processes. Next, the distribution and evolution law of the temperature field and stress field of the dam are analyzed to evaluate the overall safety of the dam. The results show that the temperature process of the dam body obtained by simulation inversion can truly reflect the temperature variation of the dam body. The maximum temperature in the dam body is typically reached within 3—5 d, and the temperature rise of hydration heat is between 4—7 ℃. The maximum temperature of pouring concrete in summer is about 35.0—39.5 ℃, while that in winter is about 25—28 ℃. Although the partial tensile stress on the spillway section surface is large in the low-temperature season, the stress in other parts does not exceed the concrete strength, and the dam safety can be guaranteed. The result indicates that pouring concrete on the large warehouse surface of the rock-filled concrete gravity dam is feasible.

Uniaxial compression tests of rock-filled concrete (RFC) and self-compacting concrete (SCC) were used to measure the complete stress-strain curves for these samples. The results showed the failure modes, peak stresses, peak point strains, elastic moduli and full stress-strain curves of the rock-filled concrete and self-compacting concrete. The results show that the failure interface of the rock-filled concrete is not only the interface between the rockfill aggregate and the self-compacting concrete matrix, but also the fracture surface in the rockfill aggregate itself. During later failure stages, the rockfill structure reduces the slope of the falling section of the stress-strain curve for the rock-filled concrete specimen. The average peak stress of the rock-filled concrete was 29% less than for the self-compacting concrete, the peak strain was 51% less, and the average elastic modulus was 42% more. The shape and position of the rockfill aggregate and the bond between the rockfill aggregate and the self-compacting concrete all affect the mechanical properties of the rock-filled concrete, which makes the test results show the characteristics of large dispersion. The theoretical stress-strain curves for the rock-filled concrete and the self-compacting concrete agree well with the measured curves.

Cemented granular materials (CGM) are composed of densely packed particles bound together by a cement matrix that partially fills the interstitial pores which provides considerable stiffness to the material. This study investigated the mechanical behavior and acoustic emission (AE) response characteristics during uniaxial compression of an artificial cemented granular material made from high alumina ceramic beads combined with a self-compacting cement paste. The samples were fabricated using the rock-filled concrete technique without disturbing the granular backbone. The results show that the compressive strength is a linear function of the matrix volume fraction. Brittle fracture is the most significant mechanical behavior. Compaction in the linear-elastic regime is the dominant behavior in the pre-peak strength region with strain-softening accompanied by strain-hardening after the peak strength. The extent of the compaction phase linearly increases with the matrix volume fraction. However, the extent of the linear-elastic phase is independent of the matrix volume fraction. For the samples with little matrix material, an AE signal occurred when the material strength approached the peak value. The AE signals of samples with more matrix material mainly occurred in the initial stages of the elastic phase. The AE signals of samples with higher matrix volume fractions were found at the mid-term stage of the compaction phase and remained high until the samples failed. The results will help to further understand the mechanical behavior of cemented granular materials, and also provide an important reference for the studies of sandstone, conglomerate, rockfill concrete and grouted sands.