Experimental Study on Influencing Factors Associated with a New Tunnel Waterproofing for Improved Impermeability

For the purpose of reliability quantitative assessment of the surrounding rock of the deeply embedded karst tunnel and the geological body around the cavern in the case of the cavern in the forepart of the tunnel face, on the basis of the upper bound limit analysis method, the energy dissipation theory, as well as the reliability theory, the dimensionless performance function of each damage area of the deeply buried karst tunnels could be established in the case of the cavern in the front of the tunnel face. Subsequently, the probability of failure and the reliability index of each damage region of the deep–bedded karst tunnel in the case of the cavern in the front of this tunnel face should be calculated through the Monte Carlo simulation sampling approach. The investigation has demonstrated that the larger the cohesion of the geotechnical body and the larger the internal friction angle within the geotechnical body, the larger the reliability indexes of the geotechnical bodies around the tunnel. The larger the diameter of the cavern and the larger the tunnel burial depth, the greater the probability of failure in the left part of the geotechnical body around this cavern, and the smaller the reliability indexes of these damage areas.

Section: Power Of External Workmentioning

confidence: 99%

Section: Information On the Projectmentioning

confidence: 99%

Section: Information On the Projectmentioning

confidence: 99%

See 1 more Smart Citation

A Calculation Method for Reliability Index of a Deep–Bedded Karst Tunnel Construction with Cavity Located Ahead of Tunnel Working Face

Wu,

Sun,

Meng

2024

“…By evaluating the possibility of using existing numerical models of mortar and concrete machinery on wood-based cementitious composites, Ndong Engone et al [16] identified the parameters that have to be adjusted in the models. In foreign countries, some new technologies have emerged, such as adding modifiers to enhance solidification effects and utilizing detection systems for construction monitoring [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Research on Temperature Field of Cement-Mixing Pile-Reinforced Soft Soil Foundation

Wang,

Xu,

et al. 2024

To investigate the mechanism of reinforcing soft soil with cement-mixing pile, based on ABAQUS secondary development, a numerical simulation study of the hydration reaction of cement-mixing piles was conducted. In this study, the influence of ground temperature variations on the distribution patterns of the temperature field in and around the pile was also considered. The temperature field of the pile–soil model can be primarily divided into two stages: the temperature rise stage (0~5 d) and the temperature decrease stage (5~90 d). The following observations were made: (1) The temperature of the pile body rapidly increased within the first 5 days, dissipating heat to the surrounding soil, leading to an elevation of the temperature in the soil around the pile and a decrease in soil moisture content. Around the 5th day, the temperature reached its maximum value, and the heat release rate of the pile body was higher than that of the surrounding soil. (2) With a 15% cement admixture, under the influence of 425# cement hydration, the temperature inside the pile increased by 5 °C, and the temperature in the soil around the pile increased by 4.2 °C. After considering the ground temperature, the temperature in the soil around the pile increased by 4.6 °C. (3) The maximum temperature generated during the hydration of 425# Portland cement is higher than that of 525#; the temperature of the soil around piles made with 425# cement is consistently higher than that made with 525#. (4) The hydration temperature of piles with a 10% cement admixture increased by 4.4 °C; for piles with a 15% cement admixture, the hydration temperature increased by 6.6 °C; and for piles with a 20% cement admixture, the hydration temperature increased by 9.1 °C. The temperature field of this structure gradually stabilizes after 7 days with increasing time and cement admixture. The results indicate that the hydration of cement-mixing piles raises the temperature of the soil around the piles. Additionally, the temperature resulting from the hydration of cement-mixing pile increases with the addition of cement.

“…Interestingly, reducing the cement percentage minimizes the compressive strength of lightweight soil when different EPS contents are used. Yuan et al [29] conducted a study to examine the variables that impact the efficiency of a new technique for waterproofing tunnels in order to make athem more impermeable. The results of the tests demonstrated a clear connection between the difference in displacement and the number of times the materials were subjected to fatigue loading, which directly affects the amount of seepage.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Deformation and Settlement Properties of Cement-Stabilized Silt Mixed with EPS Beads of Various Sizes

Ali,

Yong,

Jamil

et al. 2024

The expansion of China’s highways and railways, as well as the growing demand for them, has focused attention on the impact of traffic loads on foundation settling, uneven deformation, and ground cracking. These effects have garnered considerable research attention, with particular emphasis placed on integrating innovative materials into the soil matrix. This investigation involved loading experiments utilizing a combination of lightweight soil, expanded polystyrene (EPS), and cement. Consolidation tests assessed the extent of deformation and settlement, incorporating varying proportions of EPS and cement. The test results show that when subjected to confined conditions, the stress–strain relationship curve assumes a hyperbolic shape closely linked to the e-p curve. This shape effectively captures the unique structural characteristics exhibited by lightweight soils. As the size of the EPS particles and the applied stress increase, a corresponding rise in the strain of the specimens is observed. Simultaneously, as the strain magnitude increases, the elastic modulus experiences a decline. Additionally, it is noted that this trend further increases as the doping of the cement with EPS particles increases. When the EPS volume ratio and cement mix ratio remain constant across different specimens, there is a decrease in structural strength as the size of the EPS increases. In lightweight soil, settlement can occur rapidly, with approximately 95% of total consolidation deformation happening within a few minutes, which suggests that the settlement is instantaneous and primarily consolidation settlement. The structural strength of lightweight soil shows a negative correlation with the size of EPS, implying that larger EPS size may lead to a reduction in strength. Therefore, it is recommended to consistently use EPS beads with a diameter of 3–4 mm during construction.