Sandstone from the Longshan Grottoes in Taiyuan, China, was the research object of this paper. The sandstone samples were soaked in distilled water, Na₂SO₄ solution, and NaCl solution and subjected to freeze–thaw testing. Sandstone specimens were treated with 0, 5, 10, 15, 20, 25, and 30 freeze–thaw cycles. The mass ratio, P-wave velocity, surface hardness, uniaxial compressive strength, and other physical-mechanical features of rock samples were measured after different numbers of cycles. The results of mercury injection, scanning electron microscopy, and X-ray diffraction were combined to explore the damage mechanisms and characteristics of the rock samples under the combined action of chemicals and freeze–thaw cycles. It was found that the damage degree of sandstone increased logarithmically with the number of cycles, with Na₂SO₄ solution causing the most damage. Damage variables D of the samples soaked in distilled water, Na₂SO₄ solution, and NaCl solution after 30 freeze–thaw cycles were 3.89%, 6.51%, and 4.74%, respectively. The difference in damage between the solutions is caused by the combination of frost heave, dissolution, and salt crystallization, and the damage process generally occurs from the inside and the outside and is manifested as an increase in the number of macropores and the appearance of new pores. Freezing–thawing and salt action are important causes of the powdering and detachment of sandstone in the Longshan Grottoes.

Although the fully grouted tension anchorage system (T-anchorage system) has been widely used in the field of anchoring of earthen heritage sites, it has always suffered from the failure of the bolt–slurry interface debonding and the strong attenuation of the shear stress of the bolt–slurry interface along the embedment length. In this article, a new type of fully grouted tension–compression composite anchorage system (TC-anchorage system) is proposed, which is made up of a pressure bearing system with the same diameter of the anchor hole at the end of the tension bolt. The in situ anchorage, pull-out test and interfacial stress–strain monitoring were carried out for the T-anchorage systems and the TC-anchorage systems. This was based on the preliminary analysis and comparison of the structure and working mechanism of the two anchorage systems. The test results show that: the average ultimate load of the TC-anchorage system is about 40% higher than that of the T-anchorage system. TC-anchorage systems have the characteristics of small elastic deformation and large plastic deformation. The strain at the bolt–slurry interface varies progressively along the embedded length with the increase of load in a positive skewness–bimodal–negative skewness curve. The working mechanism of TC-anchorage systems includes three progressive stages: bolt–slurry interface debonding, conical slurry formation and slurry extrusion. The research conclusion provides a reference for the application of TC-anchorage systems in the protection and reinforcement of earthen heritage sites.

The degree of damage to heritage structures in arid areas can be particularly serious due to long‐term exposure to a harsh arid climate. In this paper, the characteristics of evaporation and cracking of soil taken from heritage structures with different NaCl concentrations are experimentally investigated by subjecting saturated soil samples taken from the Wang‐Jing tower in Weihui City, Henan Province. Making soil sample of water content of 110% is used to test the rate of evaporation at a constant temperature and humidity, through which the changes in the evaporation rate, water content, fracture development, and fracture fractal dimension are obtained. The results show that, (1) with higher water content, NaCl can affect the evaporation process by increasing the matrix suction of the soil of the Wang‐Jing tower and then affect the cracking process of soil. When 0%, 1%, 2%, and 4% NaCl are added, the residual water content of the samples is 3.15%, 4.23%, 4.82%, and 5.89%, respectively, which show an obvious trend of increasing water content; (2) the period with a stable fracture fractal dimension of the samples is shortened with an increase in NaCl concentration, and its maximum fractal dimension is reduced in turn; and (3) at a lower water content, NaCl crystallizes and precipitates in the pores of the soil, which provide a cementitious effect among the soil particles, thus inhibiting crack development.

Freeze–thaw cycles under the conditions of snowmelt and rainfall infiltration in winter are triggers for petroglyph weathering. Rock samples from the Helan Mountains were subjected freeze–thaw cycles under various conditions in laboratory testing, and the mass, elastic wave velocity and unconfined compressive strength were tested. The results show that the mass loss rate, wave velocity and compressive strength decreased. In addition, according to XRD analyses, the content of calcite and feldspar in the samples decreased, and according to SEM analyses, the microscopic pores grew. Considering the mass, mineral content and micro-voids, the variation decreases in the order: snowmelt group, rainfall infiltration group, normal freeze–thaw group. However, for wave velocity and compressive strength, the opposite results were observed. This research contributes to a better understanding of the weathering processes and mechanisms of petroglyphs in the Helan Mountains in winter.

The full-length bond wood tensile anchor system (WTS) conventionally used in earthen sites is primarily broken by the debonding of the bolt–slurry interface. To solve this limitation, material performance and pull-out tests were performed for a new type of wood tension–compression composite anchor system (WTCS) and WTS, and the strain of the bolt–slurry and the slurry–soil interface were monitored. A comparison of test results indicated the following: The average pull-out force of the WTCS is approximately 23–51% higher than that of the WTS. The WTCS has the strong ductility characteristics of small elastic and large plastic deformation. As the load increases, the strain at the bolt–slurry interface changes from a negative index of low strain to a high-strain “S” curve at the end along the bond length. The peak value of slurry–soil interface strain exhibits a transition from the front part of bond length to the middle and back parts of bond length. The mechanical operating mechanism between bolt and slurry is divided into three simplified progressive structural force models, namely “1,” “T,” and “Y.” Finally, the calculation formulas of the average pull-out force of the WTCS are provided.