Experimental study on the properties of a polymer-modified superfine cementitious composite material for waterproofing and plugging

When the opening rate of the cutter head of tunnel boring machines is insufficient for the removal of excavated soil in a timely manner, the soil tends to accumulate in front of the cutter head and inside the earth or slurry chamber, leading to mud caking. High-pressure water jetting is an effective method for removing mud cakes. This study explored the influence of high-pressure water jet parameters on the efficiency of mud cake cleaning by using highly weathered argillaceous siltstone as experimental materials. Mud cake compaction equipment and high-pressure water jetting devices were developed. In addition, the impact of jetting parameters such as jet pressure and flow rate on the mud cake cutting performance was investigated. The results indicated that with an increase in the erosion distance, the cutting width of the mud cake first increased and then gradually decreased to zero, while the cutting depth progressively diminished. Under the same jet pressure, when the flow rate increased from 49.1 L/min to 110 L/min, the cutting width of the high-pressure water jet increased. With further increase in the flow rate from 110 L/min to 202.8 L/min, the cutting width decreased and the cutting depth increased. Under the same jet flow, the increase in water pressure resulted in greater cutting width and depth.

Section: Introductionmentioning

confidence: 99%

Experimental study and mechanism analysis of high-pressure water jet for mud cake cutting during shield tunneling

Ji,

Liu,

Yang

et al. 2024

“…Lan et al (2021) and Yuan et al (2019) have put forward effective grouting schemes to address tunnel water inrush problems. Jianyong Han et al (2023) studied a high-performance and effective polymer modified composite material, the research results provide guidance for improving the impermeability of grouting material. Hua Tao et al (2023) conducted a study on the range of grouting reinforcement for karst water-rich tunnels under Vgrade surrounding rock using numerical simulation, combined with seepage and stability analysis.…”

Section: Introductionmentioning

confidence: 99%

Prediction of water inflow and analysis of surrounding rock stability in unfavorable geological mountain tunnel

Chen,

Liu,

et al. 2024

During the construction of a mountain tunnel, water inflow and rock instability are common occurrences due to unfavorable geological conditions, posing serious threats to construction safety. This study focuses on a proposed mountain tunnel and employs multiple formulas to predict potential water inflow during excavation. Based on the amount of water inflow and deformation of surrounding rocks, comprehensive determinations are made for the thickness of grouting rings and permeability coefficients. The results demonstrate that: 1) Different formulas yield slightly varied outcomes but overall trends remain consistent; considering various calculations, the normal water inflow for this tunnel is approximately 115.5908×103 m3/d with a maximum at 210.9100×103 m3/d 2) Increasing grouting ring thickness or decreasing permeability coefficient can effectively reduce water inflow, but the reduction range is gradually narrowed. 3) Pre-grouting curtains have an evident effect in enhancing stability; however, their effectiveness decreases with increased thickness. 4) Taking into account both safety and economic factors, it is recommended that the grouting ring thickness be set at 8 m with a permeability coefficient equaling one 100th that of surrounding rocks for this tunnel project.

“…By studying the macroscopic and microscopic fracture of granite and establishing the correlation between the microscopic structure of rock mass and macroscopic fracture, we can deeply understand the mechanism and process of rock fracture, which is of great significance for the safe construction and green operation of engineering construction. At the same time, it can also provide important support for predicting and controlling the fracture behavior of rock (Xia et al, 2021;Chen et al, 2022b;Chen et al, 2022c;Sun et al, 2019;Han et al, 2023). 10.3389/feart.2024.1369814 In recent years, both domestic and international scholars have conducted experimental and simulation studies on the macro-micro failure characteristics of rock mass and rock heterogeneity (Peng and Chen, 2021;Liu et al, 2020;Zhang et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Research and application of macro-micro fracture correlation of heterogeneous granite

Chen,

Su,

Gao

et al. 2024

Granite structure has the characteristics of discrete distribution and random distribution of minerals, which is particularly critical to the stability of surrounding rock of underground caverns, and the research process is extremely complicated. In this paper, the granite of Dagangshan tunnel in rock sections of class Ⅲ was taken as the research object, and the mineral composition and proportion, the macro and micro characteristics of granite was analyzed by XRD analysis, SEM and laboratory compressive test; Dagangshan tunnel’s section model with surrounding rock of class Ⅲ was established using the particle flow program PFC and the numerical simulation was done, thus the influence of micro composition and proportion on surrounding rock masses’ stability with the tunnel excavation was analyzed. Results show that: The content of illite and albite is the most, and illite is the weak mineral of the granite. For the granite of Dagangshan tunnel with rock masses of class Ⅲ, the rock failure is mainly caused by shear force and secondary by tensile force. Fracture is mainly concentrated in the enrichment area of “weakened minerals,” where as the breakthrough point and expands to other parts, and further connects. The “enhanced minerals” are basically stable because of their high hardness and strong link between each other. After tunnel excavation, cracks of tunnel’s side walls and the arch foots are more serious, so the supporting measures of these parts should be strengthened.