Abstract
To efficiently and accurately predict the effects of twin tunneling on adjacent buried pipelines, the effects of upward and downward relative pipeline-soil interactions were considered. A series of numerical parametric studies encompassing 8640 conditions were performed to investigate the responses of a pipeline to twin tunneling. Based on the dimensionless analysis and normalized calculation results, the concept of equivalent relative pipeline-soil stiffness was proposed. Additionally, expressions for the relative pipeline-soil stiffness and relative pipeline curvature and for the relative pipeline-soil stiffness and relative pipeline settlement were established, along with the related calculation plots. Relying on a comparison of prediction results, centrifuge model test results, and field measured results, the accuracy and reliability of the obtained expressions for predicting the bending strain and settlement of adjacent buried pipelines caused by twin tunneling were validated. Based on the calculation method, the maximum bending strain and maximum settlement of pipelines can be calculated precisely when the pipeline parameters, burial depth, soil parameters, and curve parameters of ground settlement due to tunneling are provided. The proposed expressions can be used not only to predict the maximum bending strain and maximum settlement of pipelines caused by single and twin tunneling but also to evaluate the effects of single and twin tunneling on the safety of existing buried pipelines. The relevant conclusions of this article can also provide a theoretical basis for the normal service of buried pipelines adjacent to subway tunnels.
Highlights
Due to stratum displacement induced by shield construction, additional stress and displacement are inevitably produced in adjacent existing buried pipelines, which further affect the normal use of such pipelines, or even leads to their failure or burst [1]. e issue of tunnel-pipeline-soil interaction is receiving increasingly close attention and is being widely explored by geotechnical scholars in many systematic and meaningful studies [2, 3].Following the theory of continuum elasticity, a new foundation model established by Klar et al [4] was used to analyze the issue of tunnel-pipeline-soil interaction and was compared with the theory used by Attewell et al [5]
Yu et al [6] further explored this problem, established a foundation model more suitable for the analysis of this issue, and compared its results with the results of Klar et al [4] using the theory of continuum elasticity
Klar and Marshall [7] adopted the theory of continuum elasticity to demonstrate that the volume loss deduced from the ground settlement under the greenfield condition was equal to that deduced from pipeline deformation in the presence of pipelines, and put forward a simple expression for predicting the bending moment of pipelines
Summary
Due to stratum displacement induced by shield construction, additional stress and displacement are inevitably produced in adjacent existing buried pipelines, which further affect the normal use of such pipelines, or even leads to their failure or burst [1]. e issue of tunnel-pipeline-soil interaction is receiving increasingly close attention and is being widely explored by geotechnical scholars in many systematic and meaningful studies [2, 3]. Based on the equivalent soil shear strain proposed by Marshall et al [11], Klar et al [12] solved the difficult problem of determining relative pipeline-soil displacement and offered the procedure for calculating the maximum bending moment of pipelines caused by tunneling by considering soil nonlinearity. To study pipeline-soil interactions, a series of numerical parametric analyses were performed by adopting the curvilinear equation proposed by Vorster et al [10] for describing the ground surface settlement caused by tunneling On this basis, the calculation formulas and design charts which can be used to predict the maximum bending strain and maximum settlement of pipelines caused by single and twin tunneling were proposed. The calculation formulas and design charts which can be used to predict the maximum bending strain and maximum settlement of pipelines caused by single and twin tunneling were proposed. e results obtained by the proposed method are more accurate than those by other methods and can be used to study the influence of multi tunnel excavation on nearby buried pipelines
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