To address the mechanical damages of limestone under the coupled mechanical(M)-hydrological(H)-chemical(C) effects, we performed uniaxial compression experiments and dissolution kinetics experiments on limestone in flowing and static solutions for different lengths of time. Through experiments, the peak strengths of the limestone under coupled MHC effects for different time lengths and the major ion concentrations in solutions were obtained. By analyzing the strength damage and chemical dissolution kinetic characteristics, we achieved the strength damage equations and chemical dissolution kinetic equations. Results show that when the solution shifted from the static state to the flowing state, and as its acidity increased, the peak strength loss of the limestone rose as well. The solution mobility had a more significant impact on the peak strength loss than the solution pH value. The limestone dissolution in flowing water was higher than in static water, indicating that solution mobility would promote the limestone dissolution. Among the contributing factors to limestone dissolution, the solution pH value showed the strongest impact, followed by the common-ion effect and then the salt effect. The research result is expected to provide a theoretical basis for maintaining the stability of rocks in geotechnical engineering practice and protection of stone cultural relics.

Prestressed anchor cable is widely used in geotechnical engineering to control the displacement or landslide of an unstable slope. However, the traditional cable anchor is made of steel material, which is easy to get rust in a corrosive environment. Basalt fiber-reinforced plastics (BFRP) are a kind of emerging compound material, with a good performance of high strength, low weight, and anticorrosion. Herein, an innovative large-tonnage pressure-type prestressed anchor is made with BFRP. This large-tonnage BFRP anchor cable has seven bunch structures of the “BFRP-connector-strand.” In each bunch of the “BFRP-connector-strand,” three BFRP tendons and one steel strand are connected inside a steel sleeve connector using the epoxy resin adhesive. The ultimate load-bearing capacity of this BFRP cable anchor can reach 202.38 tonnages. At the ultimate tensioning force condition, the strain of BFRP tendons for this large-tonnage BFRP anchor cable ranges from 1.51% to 1.76%. In the tensioning operation, there is a linear growth relationship between the tensioning force and the strain for this BFRP cable anchor. Once the tensioning force reaches the ultimate strength of this BFRP anchor cable, this cable will present system failure. This situation primarily results from the failure of the “BFRP-connector-strand.” The failure modes of this BFRP anchor cable can be classified into three types: the steel strand rupture, the steel connector rupture, and the BFRP tendon rupture. During the tensioning operation, due to the length difference of the BFRP tendons, this large-tonnage BFRP cable anchor presents an end-off-axis effect. It makes the load bearing of the BFRP tendons 5.00~6.60 times larger than that of the no end-off-axis effect. Nevertheless, due to the plastic deformation of the end steel anchor sleeve, the influence of the end-off-axis effect decreases with the increase of applied tensioning force. The load-bearing capacity of this large-tonnage BFRP cable anchor reaches 87.70~91.50% of its theoretical value.

Rock is a nonhomogeneous material composed of one or more minerals. The structure and properties of internal mineral crystals have an impact on its macro-mechanical properties. Taking the Longmen Grottoes limestone as the research object, firstly, the mineral composition and macro-mechanical properties of the limestone are obtained, and through simulation and calculation of the crystal structure, chemical bond properties and elastic properties of minerals, this paper reveals how the mineral crystal structure and properties affect the macro-mechanical properties of the rock. Tests show that the main mineral components of the limestone in Longmen Grottoes are calcite and dolomite crystals. The uniaxial compression strength and elastic modulus of limestone with different calcite and dolomite contents are obviously different. From the study of crystal structure and chemical bond properties, it is learnt that the calcite and dolomite have similar crystal structures, but due to the difference of the chemical bond strength of Ca-O and Mg-O, the overall calcite crystal has a weaker chemical bond strength than the whole dolomite crystal. The First Principle simulation suggests a correlation between the overall crystal chemical bond strength and elastic modulus of the crystal. Therefore, studying the crystal structure and properties of minerals provides a significant research direction for revealing the mechanism of the macro-mechanical properties of rocks.

Two types of basalt fiber-reinforced polymer (BFRP) anchor cables—a Tension-concentrated anchor cable (TCAC) and a Pressure-dispersed anchor cable (PDAC)—were developed through structural modification of the rod body and implemented for reinforcing fractured rock masses on highway tunnel slopes in western Henan Province, China. The feasibility of replacing conventional steel rods with BFRP bars and the corresponding anchorage mechanisms were investigated. The experimental results indicate that the axial force distribution differs markedly between the two anchors. The TCAC exhibits a decreasing axial force with depth, forming a concave distribution under low load and a convex distribution under high load, with the force approaching zero beyond 100 cm. In contrast, the PDAC displays a relatively uniform axial force that sharply decreases near the bearing plate, and, under increasing load, the axial force at the anchorage end tends to rise; Both anchors demonstrate single-peak interfacial shear stress distributions. For the TCAC, the peak progressively shifts toward deeper regions with increasing load, whereas the peak of the PDAC consistently appears near the bearing plate, with only its magnitude increasing. Stability analysis using GEO5 software reveals that the slope safety factor increases from 1.32 (without anchors) to 1.36 (with anchors), thus satisfying the design requirements. The results reveal the different anchoring mechanisms of tension-concentrated anchor cables and pressure-dispersed anchor cables, providing practical guidance for their selection and application in slope stabilization engineering.

Taking two types of limestone with different mineral compositions as research objects, we conducted experiments on the mass, longitudinal wave velocity, ion concentration of solution, fracture morphology, and micromorphology of two types of limestone specimens eroded by acidic hydro-chemical solution. We investigated specimens’ damage time-dependent physical properties, dissolution, structure, discussing mineral composition effects and destruction. Results show that the mass loss rate of two types of limestone specimens eroded by acidic hydro-chemical solution increases with the increase of immersion time in a power function, and the longitudinal wave velocity decreases and then fluctuates in a small range. The specimen fracture degree increases with the increase of the immersion time, and the rock micro-structure changes from dense and uniform into loose and porous. The mass, the longitudinal wave velocity, the fracturing morphology, and damage to microscopic morphology of specimens increase with the increase of solution ion concentration. The acid rock reaction rate of limestone A is lower than that of limestone B, while the hydrolysis reaction rate is higher. The mass loss rate, the longitudinal wave velocity loss rate, the ion concentration, and the damage degree of the macro-and micro-structure of limestone A are higher than that of limestone B.