Abstract: This paper studies the application of grouting reinforcement technology in the reinforcement of sand layer in tunnel and underground engineering. The influence of different factors on the unconfined compressive strength of solid sand was studied by orthogonal horizontal test, combined with physical properties of cement slurry and water content of sand layer. The test results show that the water content of sand, cement water cement ratio and curing time have significant effects on the strength of solid sand, and the curing time has the greatest effect. Finally, the optimal slurry ratio was determined as 8% sand water content, 28 days curing time and 0.8 water-cement ratio. Under this ratio, the strength of the solid sand body was the best, and the gel time and viscosity of the slurry also met the engineering requirements. This study provides an important reference for grouting reinforcement engineering under similar geological conditions. Read More

Abstract: The theoretical study of blow fill is of great significance for the increasing land reclamation projects year by year. Through reading the online literature, combining the physical properties of the blown fill and the existing consolidation theory, the consolidation theory suitable for most scenarios of the blown fill is selected, and the advantages and disadvantages of the existing methods are introduced. Read More

Abstract: In recent decades, shotcrete technology has developed rapidly in civil engineering. A lot of practice at home and abroad has proved that shotcrete has shown its unique functions and obvious benefits in the engineering fields such as supporting lining of mine roadway and underground engineering, reinforcing and reinforcing of building structure, stabilizing of rock and soil slope, building of thin wall structure with complex shape and water transmission and filling structure. It can be expected that with the continuous development of transportation, energy and material industry, a large number of urban underground engineering and complex public buildings are constructed, and the increasing number of building structure reinforcement projects, the application field of shotcrete will be increasingly broad. This paper mainly introduces the research progress, construction technology and future development direction of shotcrete in recent decades. Read More

Abstract: Artificial freezing technology is increasingly applied in engineering practice due to its advantages of not being limited by the scope and depth of support, effectively preventing water inrush, and controlling soil deformation. However, how to avoid the impact on the structure and environment caused by soil frost heave and thawing settlement has always been a problem for engineering and technical personnel. Grouting technology is an important auxiliary technology in underground engineering construction, which has mature applications in lifting and strengthening strata, as well as anti-seepage and plugging of strata. This article discusses the feasibility of the combined construction of grouting and freezing method from the perspective of the combination application of two technologies. Read More

Abstract: Mircowave absorption materials can solve the problem of electromagnetic pollution, but corrosion in harsh environments will lead to a decrease in its absorption performance, so it is important to study materials that are both mircowave absorption and corrosion-resistant. In this experiment, FeSiAl alloy was coated Al2O3 (noted as FeSiAl@ Al2O3 coating) with aluminum chloride hexahydrate as aluminum source, and its mircowave absorption and corrosion resistance properties were studied. The results show that the mircowave absorption and corrosion resistance performance of FeSiAl@ Al2O3 coating both are obviously improved. The minimum reflection loss of FeSiAl@Al2O3 is -43.4 dB, the matching thickness is 2.3 mm, and the effective bandwidth is 2.97 GHz. For the coated alloy, the corrosion current decreases from 3.538*10-4 A/cm2 to 3.499*10-4 A/cm2, and the corrosion resistance increases from 96.1 ohm to 225.1 ohm. This provides an effective way to develop iron aluminum silicon materials that combine microwave absorption and corrosion resistance. Read More

Abstract: In order to provide a channel for centralized injection of gas or sealing materials from the ground to the underground fire zone, and thus achieve safe mining of the underground 708 working face. Five fire extinguishing boreholes and one monitoring borehole were drilled on the construction ground of the west wing coal seam of Mount Huangshan Coal Mine, and comprehensive fire extinguishing measures such as injecting liquid CO, injecting fly ash, yellow sand, green sand, loess and LFM light filling materials were taken, with a total plugging space of 877.8m3. The monitoring results show that the fire area of the+708 working face has been extinguished, indicating that the drilling fire extinguishing technology adopted has played a good role in controlling the closed fire area of the underground 708 working face. Read More

Abstract: In order to explore the tensile properties and damage mechanism of larch wood along grain, Northeast Larch was taken as the research object. The deformation characteristics, failure mode and stress-strain curve properties of larch wood under tension along grain direction were analyzed by monotonic tensile test on 12 specimens. By means of scanning electron microscopy, the damage and fracture characteristics of wood fiber were analyzed from the microscopic point of view, and the mono-stress failure mechanism of wood was further revealed. The results show that the body of larch wood can be divided into three stages: rapid growth, slow growth and brittle fracture. Due to the difference between early and late wood tracheids, longitudinal splitting and transverse tearing of tracheid walls usually occur. On this basis, a constitutive model was established to describe the longitudinal tension of larch wood. Read More