Prediction of the stress-strain state and stability of the front of tunnel face at the intersection of disturbed zones of the soil mass

Abstract

The article presents a numerical solution of the spatial elastic-plastic problem of determining the stability of the tunnel face soils at the intersection of disturbed zones of the soil mass. The relevance of the study is related to the need to take into account the zones of disturbed soils when assessing the face stability to calculate the parameters of the support. Based on the finite element method implemented in the PLAXIS 3D software package, the construction of a finite element system "soil mass-disturbance-face support" and modeling of the intersection of the disturbed zones of the soil mass were performed. To assess the condition of soils, deformation and strength criteria are taken. The deformation criterion is expressed by the value of the calculated displacement of the tunnel contour in the face, and the strength criterion - by the safety coefficient until the maximum values of the stress state are reached according to the Coulomb–Mohr criterion. The results of the study are presented in the form of histograms of the safety coefficient dependences on the distance to the disturbance at different bending stiffness of the face support structure, as well as the isofields of deformation development. The parameters of rockfall formation in the face zone at the intersection of zones of disturbed soils were determined. The local decrease in strength and deformation properties in the rock mass along the tunnel track should be taken into account when assessing the stability of the tunnel face and calculating the parameters of the support. Within the framework of the constructed closed system, a qualitative agreement of the simulation results with the case of a collapse in the face during the construction of the Vladimirskaya-2 station of the St. Petersburg Metro was obtained.

Substantiation of pitwall parameters in rock mass with steeply dipping bedding

“…В последнее время с развитием компьютерных технологий все большее распространение получают методы численного моделирования [12][13][14][15][16][17][18][19][20][21][22][23][24][25], среди которых широкое применение на практике нашел метод конечных элементов. В отличие от аналитических методов, метод конечных элементов позволяет оценивать особенности деформирования откосов на всех стадиях его формирования.…”

Analysis and prediction of surface settlements during the digging of underground mining works (Algeria)

“…For many infrastructure projects, uncertain ties regarding subterranean soil and rock conditions contribute significantly to the overall technical and financial risks of the project. In this sense, the construction of underground struc tures poses the problem of stability during the work, particu larly at the face [1], and the type of support to be implemented to guarantee deformations at the level of the tunnel walls.…”