ABSTRACT

This paper presents further developments of the principle of Construction Process Mechanics of rockmasses, The principle of loading variations analyses in space-time is systematically described. To demonstrate the applicability of the theory and method, the effect of the construction process of two practical engineering cases are analysed.

ZUSAMMENFASSUNG

Das Mechaniksprinzip vom Konstruktionsprozess des Massenfels wird in diesem Aufsatz weiter Entwickelt.. Das Prinzip von Variationsladungsanalyse mit dem Zeit-Raumseffekt wird systematisch erklaert. Um die Anwendungsmoeglichkeit der Theorie und der Methode zu anschaulich darstellen, das Mechanikseffekt des Konstruktionsprozess wird fuer zwei praktische Anwendungsbeispielen zergliedert.:

RESUME

Dans ce papier le development se fait pour principles de la mechanique de process de construction. Le principle de variable analyse considerant effet de temps et de Space est present ´e. Pour demonstrer l´appilicabilite de le theorie et la methode, l´èffect de processe de construction pour ce deax examples sont analyses

Introduction

For rock works in complex geological environments, the process of excavation and supporting interacts closely with the mechanical behavior of rocks, in both time and space. This paper makes further clarification on the scientific principles of the subject, with demonstrative examples from engineering practice.

Key points of construction process mechanics of rock masses

Generally, fractured or soft rocks' mechanical properties are non-linear. Therefore, result of loading depends on the loading stress paths. For this reason, we have first put foreword a new research direction of construction process mechanics of rock mass.(Zhu and He 1995: 294) Some key concepts of the theory are:

  • The stability of a rock mass depends not only on its natural features but also closed on the man-made disturbances.

  • Construction in a complex rock mass is a dynamical non-linear mechanical process and the rock stability is largely controlled by the stress paths and stress history. Optimization analyses of construction scheme and order should be performed before the construction work.

  • Optimal excavating and supporting measures should be adopted according to the characters of site-specific conditions of a rock mass and the objectives of the engineering project, thus confining the unfavorable effects and potential dangers within a possibly small range of tolerance.

Principle of analysis for load variations in time and space

Based on the Principle of Construction Process Mechanics considering the time-space effect a new principle of Variation Loading Analyses is presented recently as following: (Zhu, et. al. 2000: 389)

  • The strength and deformability of fractured rocks are strongly governed by the fracture system and initial stress field. Special attention should be placed on the interactions of directions between the layout of construction, initial stress and fracture system. Prediction of the mode and extent of instability should be therefore based upon the relevant correlation of those three factors.

  • For large-scale rock works that have a fairly long construction period, the continuously advanced excavation and supporting supply repeated loading and unloading process upon the surrounding rocks in both time and space.

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