This paper presents a method to predict the impact of underground tunnel construction on nearby piles using non-linear soil-pile-tunnel interaction. Two stage analysis method have been used considering Kerr foundation model. Greenfield ground settlements have been compared with site-specific instrumentation data of East-West Metro Project, Kolkata, India and results obtained were found to be in good agreement. It has also been observed that the Kerr foundation model considers soil spring over Pasternak's model and hence yields reduced pile deflection compared to Pasternak's model. Non-linear analysis considers non-linear stress-strain relationship and so yields more pile deflection than linear analysis under large deformation. Validation has been performed with case studies in published literature. Irrespective of end conditions, critical bending moment in pile develops at the tunnel centreline depth and at the fixed ends. Soil is a non-elastic material and due to its own shearing strength, the soil also absorbs some portion of the ground deformation before transferring that to the pile. So, consideration of non-linear Kerr model captures a realistic response of the pile. An accurate and cost-effective solution method of non-linear tunnel-soil-pile interaction model has been developed for easy application by practicing engineers using MATLAB software which is commonly available in most of the design.

In today's urban development, Earth Pressure Balance (EPB) Tunnel Boring Machines (TBMs) play a vital role. It's crucial to design a comprehensive monitoring system to control surface settlement and prevent damage to surface structures. This study focuses on creating prediction models for estimating ground surface settlement. Two soft computing techniques, namely ANN-CFB and ANN-BP, were used for this purpose. The models were validated using operational data from the Qom metro Line A, specifically the between A14 and A10 stations. Additional input parameters were incorporated using an image processing approach to include soil properties for each segment. As a result, the most accurate ANN technique was employed to predict ground surface settlements for the mentioned project. The correlation coefficients for training, testing, validation, and the overall result were found to be 0.99439, 0.97873, 0.96381, and 0.98824, respectively. Through sensitivity analysis, the study explored the connections between different parameters and ground surface settlement. The outcomes reveal strong agreement between predicted values and real data. Notably, the parameter 'cutter head torque' exhibited the highest impact on surface settlement (8.48%), while 'Pressiometric Modulus (Ep)' had the least impact (4.24%).

In tunneling technology, Earth Pressure Balance-Tunnel Boring Machine (EPB-TBM) technology operations require altering excavated soil rheology through soil conditioning, a vital aspect for optimal counterpressure control and soil extraction. This transformation is achieved by introducing additives like foam, and inherits its time-dependent behavior. Having observed a discrepancy in the stability of two foams generated with different flow rates, the core objective of research is exploring the influence of this parameter on time-dependency of mechanical properties of conditioned soil. This aspect is then studied also through a semi-quantitative analysis aimed to investigate correlations between the generation flow rates, the Foam Expansion Ratio, and used Foam Injection Ratio with the time-stability of conditioned soil properties.

Bentonite slurry is frequently used to temporarily stabilize the excavation for slurry tunnel boring machines (TBMs) driving in permeable soils, such as sand and gravel. In this study, two types of bentonite slurries (BS1 and BS2) were subjected to a series of infiltration column tests and modified fluid-loss tests under various pressure levels. Monitoring of water discharge and pore pressures at different depths of the sand bed enabled the identification of two effective sealing patterns during infiltration: the formation of a filter cake and rheological blocking. BS1 exhibited a tendency to form a filter cake, which played a vital role in effectively transferring the applied pressure to the underlying soil skeleton. The application of higher pressure facilitated the rapid formation of a filter cake, resulting in a shorter time span for slurry invasion and minimizing fluid loss. On the other hand, rheological blocking was dominant when using BS2, and the maximum infiltration distance was found to linearly increase with the applied pressure. A comparison between the measurement and a simple prediction model derived from Darcy's law revealed an overestimation of the infiltration distance during slurry invasion. Furthermore, based on the modified fluid-loss test, higher pressure was found to densify the filter cake and result in lower hydraulic conductivity.

During the excavation of the Alaskan Way Viaduct replacement tunnel in Seattle, Washington, a 17.5 m diameter tunnel boring machine (TBM) nicknamed Big Bertha was damaged after encountering unexpected subsurface conditions. Significant dewatering of multiple aquifers was required to reach the TBM for repairs. Groundwater drawdown and soil consolidation associated with dewatering created a 0.4 km(2) region of initial subsidence with maximum vertical settlements exceeding 2.5 cm between August and December 2014. Dewatering wells remained operational until January 2016 and likely contributed to observed groundwater drawdown in areas outside the region of initial subsidence. To determine how an urban landscape with complex and poorly constrained geologic and hydrologic conditions responds to an extended period of dewatering within multiple aquifers, the rate, duration, spatial extent, and magnitude of dewatering-related displacements were analyzed by combining three paths of Sentinel-1 interferometric synthetic aperture radar data spanning November 2014 to October 2019 into a time series of vertical surface deformation using the minimum acceleration algorithm. Our results show that post-dewatering ground rebound within this complex hydrogeologic system occurred at faster rates and with more significant spatial deformation variability than initial subsidence, reaching rates of up to 17 cm/year coupled with potentially hazardous differential rebounds across short distances. In addition, prolonged groundwater pumping at depths greater than 60 m appears to have induced delayed subsidence over a larger area of similar to 20 km(2), reaching magnitudes of up to 3 cm and lasting for over 3 years after the cessation of pumping.

This paper presents a case study of the clogging of a slurry-shield tunnel-boring machine (TBM) experienced during tunnel operations in clay-rich argillaceous siltstones under the Ganjiang River, China. The clogging experienced during tunneling was due to special geological conditions, which had a considerably negative impact on the slurry-shield TBM tunneling performance. In this case study, the effect of clogging on the slurry-shield TBM tunneling performance (e.g., advance speed, thrust, torque, and penetration per revolution) was fully investigated. The potential for clogging during tunnel operations in argillaceous siltstone was estimated using an existing empirical classification chart. Many improvement measures have been proposed to mitigate the clogging potential of two slurry-shield TBMs during tunneling, such as the use of an optimum cutting wheel, a replacement cutting tool, improvements to the circulation flushing system and slurry properties, mixed support integrating slurry, and compressed air to support the excavation face. The mechanisms and potential causes of clogging are explained in detail, and the contributions of these mitigation measures to tunneling performance are discussed. By investigating the actual operational parameters of the slurry-shield TBMs, these mitigation measures were proven to be effective in mitigating the clogging potential of slurry-shield TBMs. This case study provides valuable information for slurry-shield TBMs involving tunneling in clay-rich sedimentary rocks.