With the rapid development of electrolytic manganese industry, the environmental problems caused by the storage of electrolytic manganese slag are particularly prominent. It not only occupies land resources, but also easily causes heavy metal pollution in soil, surface water and groundwater. Therefore, it is necessary to treat electrolytic manganese slag safely and effectively. The paper mainly studies the solidification/stabilization of electrolytic manganese slag and its environmental safety for road filling, in order to open up a new way of harmless and resource utilization of electrolytic manganese slag. In this paper, lime and fly ash were used as stabilizers and cement was used as curing agent to stabilize manganese slag, and the stabilization effect of Mn and Pb in manganese slag was studied. The stabilization effect of manganese (Mn) and lead (Pb) in manganese slag was studied. The results show that the dosage of stabilizer quicklime is 2.5%, fly ash is 3%, and the dosage of solidifying agent cement is 12%, the solidification/stabilization effect is the best compared with other ratios, then the leaching concentrations of Mn and Pb meets the requirements of China’s surface water environmental quality standards for category III water sources, which can be used as domestic water after treatment. Under the optimal ratio of stabilization effect, the compressive strength and slump are 13.8 MPa and 50 mm, respectively. The research results of the paper can provide a new way for the harmless treatment of manganese slag and the resource utilization of new materials.

In this study, a series of laboratory fracturing experiments were conducted on samples mined from reservoirs of the Guanyinqiao Member shale in Xishui County, Guizhou Province, using a traditional triaxial fracturing simulation system. Based on the experimental results, the breakdown pressure and effective stimulated reservoir volume were obtained for four fracturing fluids (supercritical carbon dioxide, water, NO-sand, and sand). The fracture mechanism was then analyzed using acoustic emission monitoring data. Based on the curves of pressure vs injection time for different fracturing fluids, the breakdown pressure increased with increasing fracturing fluid viscosity. When sands with different viscosities were used as the fracturing fluid, the breakdown pressure first increased and then decreased with an increase in the sand viscosity. The distribution of the tracer or proppant was not only correlated with the fracturing effect, but also promotes the filling crack of the tracer and proppant at a certain viscosity as the best fracturing effect. During sand fracturing, the proppant mainly formed shear cracks. The results provide a valuable technical reference for shale gas mining.

The paper uses alkali-activated slag and fly ash as cementitious materials to pour and repair concrete. Their modification on the bonding surface of new and old concrete is studied. The new and old concrete composite specimens were prepared. The split tensile strength test of the new and old concrete specimens along the interface was carried out, and the test results of different alkali-stimulated slag and fly ash concrete as repair materials were compared and analyzed. The influence of activator modulus and other factors on the bond strength of new and old concrete interfaces was studied, and the law of its strength change was explored. The research results show that with the gradual increase in the amount of fly ash minerals, the splitting tensile strength presents a trend of first increasing and then decreasing. When the amount is 50%, the splitting surface partly occurs on the old concrete. It shows that the bonding effect is the best at this content; the alkali excitation modulus gradually increases, and the splitting tensile strength shows a downward trend. When the activator modulus is 1.3, more gelatinous substances can be observed in the section of the specimen. These overlap each other to form a tight material skeleton structure; a comparative analysis of the bonding strength of the new and old concrete interfaces with different interface agents and without interface agents showed that the alkali-activated solid waste cementitious material has the best repair performance and greater bonding strength when the water-to-binder ratio is 0.3.

Due to the extremely low permeability of shale reservoirs, large-scale reservoir fracturing is required. Hydraulic fracturing is one of the most important technologies in shale gas exploration and development. In this paper, the acoustic emission energy and the number of location and fracture surface morphology of specimens before and after fracture are studied through hydraulic sand fracturing test. The test results show that: (1) the energy ratio obtained during hydraulic fracturing without proppant is the smallest, and increasing the confining pressure, as well as reducing the displacement and viscosity of the fracturing fluid will cause the energy ratio to decrease. From the perspective of acoustic emission energy, the proppant play an important role in the generation of fractures during hydraulic sand fracturing; (2) when the confining pressure increases, the number of shale specimens before and after rupture is the largest, but the total number of locating events is smaller than the sanding ratio increased; there is no proppant hydraulic fracturing, the number of specimens before and after the rupture is the largest. And the total number reached the minimum, indicating that the proppant can play an important role in the hydraulic sand fracturing test; (3) the sand is relatively large, the specific surface and standard deviation both reach the maximum, indicating that the fracture surface roughness is the largest under the test condition, and the fracturing effect is the best, but the specific surface and standard deviation are the minimum when fracturing without proppant, so indicating that the fracture surface fracturing effect is the worst at this time.

Hydraulic sand-fracturing experiments are conducted at different proppant content and fracturing fluid viscosities on samples obtained from the shale reservoirs in the Guanyinqiao Member. The characteristics of the obtained sand-fracturing curve and proppant distribution are investigated. The test results establish that the fracture morphologies and proppant distribution after sand fracturing have significant differences. Although the proppant is favorable for increasing the fracture width, the fracture width does not increase gradually with the increase in proppant content. For both acoustic emission localization and proppant distribution, the sand fracture effect is best at a proppant content of 10%.

Conventional mechanical tests under static loading can prove that the angle of the shale bedding plane is the main reason for the anisotropy of its mechanical behavior. In order to explore the influence of the angle in the layer on the anisotropic mechanical behavior of shale, the uniaxial compression mechanical tests were carried out under the conditions of 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The results show that (1) the anisotropy degree of shale compressive strength shows the “W” type with the increase in the bedding angle, while the anisotropy degree of elastic modulus and Poisson’s ratio shows the “V” type with the influence of the bedding angle, but the minimum value of elastic modulus is around 45° and the minimum value of Poisson’s ratio is around 30°; and (2) the analysis of variance has a significant effect on compressive strength, elastic modulus, and Poisson’s ratio. Generally speaking, the anisotropic mechanical characteristics of shale have a great influence with the change in the bedding angle. The research conclusion is helpful to understand the mechanical behavior of shale.