Investigation of the Influence Area of the Excavation of a Double-Line Highway Tunnel under an Existing Railway Tunnel

Abstract

The research on the impact of the excavation of underpass tunnels has already had certain results, but there is a lack of research cases of double-line highway tunnels with oblique angles under the existing railway tunnels, especially the method of determining the area of the impact of the dynamic and static loads of new tunnels and existing trains, which can be enriched by considering them at the same time. This paper, is based on the tunnel project of the new double-line Shiqian highway tunnel with oblique angles under the Hurong railway in Wanshoushan. By constructing a three-dimensional finite element model and simulating the application of static tunnel excavation load, dynamic blasting load, and dynamic train operation load of the existing tunnel, the overall displacement of the existing tunnel and the settlement value of the bottom plate of the track surface by the static tunnel excavation load were analyzed. Then, the stresses, vibration speeds, and displacements of the tunnel due to the dynamic blasting loads and the dynamic train operation loads were obtained. The results show that the area of influence of the static loads of the new tunnel excavation on the existing tunnel is divided into three types of perturbations presenting strong, weak, and slight; the area affected by the blasting dynamic load of new tunnel excavation is a circular domain with the datum point in the tunnel section as the center; the area affected by the dynamic load of train operation in the existing tunnel is an ellipse with the center of the track surface of the existing tunnel as the datum; and there is an anomalous shape in the area affected by the blasting dynamic load of new tunnel excavation and the area affected by the dynamic load of the train operation in the existing tunnel.

Investigation on the Mechanical Characteristics of the Excavation of a Double-Line Highway Tunnel Underpass Existing Railway Tunnel under the Influence of Dynamic and Static Load

“…This study relies on the cross-tunneling project of the double-line Shiqian Highway Tunnel with an oblique angle under the Hurong Railway, in the Wanshoushan section [36].…”

“…According to the research results in the literature [36] on the impact area of the double-line underpass tunnel project in Wanshoushan Mountain, we optimize the enclosing rock classification based on photo images and over-advanced geological forecast information; quantify the deterioration of rock properties caused by dynamic and static loads using a perturbation system; determine the mechanical parameters of the rock under the influence of dynamic and static load coupling in the impact area of the cross-tunnel project using the Hoek-Brown criterion; and construct a three-dimensional model, considering the influence of dynamic and static load coupling. A three-dimensional model of the mechanical characteristics analysis of tunnel excavation of the two-lane highway tunnel under the existing railroad is constructed by considering the influence of dynamic and static load coupling.…”

“…In this paper, based on the results of the impact area of the Wanshoushan double-line cross-tunnel project studied in the literature [36], the rock body in the impact area was optimized by adopting the method of optimizing the surrounding rock grading using photo images and the information of the over-advanced geological prediction; using the disturbance coefficients to quantify the deterioration of the rock properties caused by the static and dynamic load; and determining the mechanical parameters of the rock body in the impact area of the cross-tunnel project, by taking into consideration the influence of the dynamic and static load coupling with the application of Hoek-Brown criterion, which, in turn, revealed the mechanical characteristics of the excavation for the tunnel of the double-line highway tunnel under the influence of the dynamic and static load, under the influence of the tunnel crossing the existing railway.…”

“…The new Wanshoushan Tunnel is a double-line highway tunnel, the left line intersects with Hurong Railway Tunnel at K3+674.943 (Figure 2 L 0 ) and the right line intersects with Hurong Railway Tunnel at YK3+694.291 (Figure 3 R 0 ). The 60 m before and after the intersection point of the new highway tunnel is the excavation-sensitive area [36]. Preliminarily, the excavation sensitive area is determined as Class IV surrounding rock.…”

“…Based on the disturbance situation of the field tunnel [36], referring to the rock disturbance coefficient value chart (Table 1), it is determined that the disturbance coefficient of the area affected by blasting and excavation of the cross-tunnel project is 0.5, that of the area affected by static excavation is 0, that of the area affected by the train dynamic load is 0.2, and that of the area overlapping the blasting load and the train dynamic load is 0.7.…”