<p>In modern cities due to the construction of underground structures by deep excavation, stresses are generated on the existing adjacent tunnel. It causes deformation, stepping and opening of circumferential joints which further increases due to non-linear behaviour of soil leading to tunnel failure. Hence, it is extremely important to deal this real-life problem by using simple equations for evaluating the impact on tunnel and accordingly determine the mitigation measures to secure the tunnel. This paper covers the formulation of governing differential equation idealising segmental tunnel as Euler–Bernoulli beam or Timoshenko beam along with soil as Pasternak’s model considering the non-linear response of soil and simultaneously solving by FDM using MATLAB. Further the results have been compared with previous literatures based on elastic analysis and with field instrumentation data of East–West Metro, Kolkata, India. It is found that the tunnel deflection and bending moment increases around 20% and 18% respectively for soil having Young’s modulus of 40,000&#xa0;kPa with the consideration of non-linear soil parameters. It is also revealed from the analysis that with the increase in shear stiffness at the joints (κGA) from 1/4 κGA to κGA, the deflection of the tunnel reduces about 25% and forces reduces around 70% thus minimises the impact on tunnel. Hence, temporary steel bracing system, inside the tunnel, may be installed during adjacent deep excavation, to increase the shear stiffness at the joints of the tunnel rings and thereby acts as an effective mitigation measure.</p>