3D analytical prediction of building damage due to ground subsidence produced by tunneling

Abstract

Tunnel construction entails the generation of ground settlements, which can endanger the adjacent buildings. The prediction of damages in buildings is usually based on the classical Gaussian profiles for the approximation of the subsidence trough and the equivalent beam method for modeling the response of building walls. Current available expressions refer to walls aligned transversally with respect to the tunnel axis, which usually represents the worst-case scenario. However, approximations must be done for other building alignments, since no analytical expressions are available for these cases. We propose a novel equation for the determination of the horizontal ground strain, which departs from the equations of the classical Gaussian settlement profiles. The novel formulation allows the application of the equivalent beam method in 3D and the modeling of the tunnel advance. The results show significant variations of the estimated damage depending on the wall position with respect to the tunnel axis. The paper reviews also certain relevant aspects of building damage predictions, such as the influence area of settlements and the possible contribution of ground horizontal strain to damage reduction. A parametric analysis is further performed to create a non-linear regression model that allows direct estimation of the maximum tensile strain in a building wall according to input values of geological conditions and wall and tunnel geometries.Peer ReviewedPostprint (author's final draft

Probabilistic approach to assessing and monitoring settlements caused by tunneling

“…is the resultant horizontal strain in the ground surface along the base of the beam. It is calculated based on the field of ground horizontal displacements as (Camós and Molins, 2015):…”

“…"#$% , with its reference point located at a distance ! "#$ from the origin of coordinates and aligned degrees with respect to the tunnel transverse plane (Camós and Molins, 2015). The depth of the tunnel axis and the tunnel diameter are !…”

“…The tunnel face is located at coordinate ! and it advances towards = −∞, following the criteria set by Attewell et al (1986) Camós and Molins, 2015). …”

Challenges faced for micro-tunelling works in Jadaf, Dubai for long drive on large scale projects (case study)

“…It can also be seen in the Figure that the pit is very close (around 6 meter) from the overhead bridge which is leading to the Business Bay and crossing Al Khail road. Therefore, to access work site, a special approval is required from RTA and special care is needed to monitor the vertical height limit [3][4][5][6]8,[9][10][11][12][13][14][15]. As the area is very close to the existing creek, high amount of water has caused difficulty to lower down the water table in the receiving pit and therefore other related activities such as excavation and bracing work are affected.…”

“…The poor geological condition (Low N Value) † and non-availability of sufficient cover can cause the surface settlement. Due to large amount of dewatering and high amount of load imposed by surrounding structures, chances of surface settlement and uneven longitudinal ground settlement increases [4]. Bore in unsuitable ground has the tendency to converse the string of the pipe including tunnelling head and the machine attached to it (known as CAN) ‡.…”