## 1 Introduction
[17] also investigated the settlement of pipelines induced by tunneling based on the ABAQUS program, analyzing each influence parameter's sensitivity to the settlement displacement. [PERSON] et al. [18] researched the impact of deep foundation pit excavation on the adjacent oil pipelines using the finite element software MIDAS and a field test. In addition, [PERSON] et al. [4] also used PLAXIS 3D software to numerically analyze the settlement and deformation of pipelines in soil rock composite stratum, revealing some characteristics of pipeline deformation induced by excavation. [PERSON] al. and [PERSON] al. put forward a method to optimize the structural performance of buried reinforced concrete pipelines in cohesionless soils by using the finite element method [19; 20]; [PERSON] et al. [21] developed an advanced numerical model to account for building-soil excavation interactions, and provided a new consideration for the deformation theory of adjacent buried pipelines. However, these methods are only for circular cross-sections, usually disregarding non-circular cross-sections of pipelines and their relative position to the foundation pit, which terribly limits its scope of application. In fact, irregularly shaped foundation pits are widely found in urban construction, and similar complex problems are unavoidable. A centrifuge test is an innovative experiment method which is conducted to study the mechanical behavior of buried pipelines, but there are few reports on the open-cut excavation of the foundation pit [22]. Because of the difficulty in determining the excavation and its effects on buried pipelines, the experimental model problem is extremely complex and difficult to accurately build. On the other hand, experimental testing is considered uneconomical and impractical for measuring the performance of pipelines under a high soil fill depth [19]. In light of the above problems, some researchers attempt to establish a model based on field test data, such as [PERSON] et al. and [PERSON] et al. [23; 24]. [PERSON] et al. [25] developed empirical formulae for estimating the horizontal and vertical displacement of shallowly buried pipelines caused by adjacent excavation based upon regression analyses on the amounts of field measurements in Shanghai soft ground. [PERSON] et al. [26] also used a large number of measured data to analyze the characteristics of surface settlement and deformation of a foundation pit in Beijing, and su mmarized the law of the surface subsidence and gave empirical parameters of predicted deformation. [PERSON] et al. [27] analyzed the performance of shallowly buried pressurized pipelines based on the extensive field performance data collected by means of settlement points and inclinometers located within and adjacent to the excavation. [PERSON] et al. [28] investigated the performance of a deep foundation pit excavation and its influence on adjacent piles through the results of field measurements, and the result agreed well with the empirical prediction in mixed ground. The current empirical formulae fitted by the field test data have some advantages, but some limitations also exist. These study cases mentioned above can only represent the individual, so the results do not have universality. The purpose of this study is to supply a simple and practical calculated method of buried pipeline settlement deformation, and provide services for pipeline safety evaluation during the construction period. What distinguishes this study the most from the previous solutions is the consideration of the working condition where the pipelines are not parallel to the edge of foundation pit, and the pipelines of a non-circular cross-section are also considered emphatically. A simplified mechanical model for the settlement deformation of buried pipelines and analytical solution is verified by two cases in the literature, and the sensitivity impact of various parameters on the settlement displacement is also discussed more in-depth.