Discussion on the Geometric Methods to Calculating the Fault Complexity Coefficient

Lots of faults exist in rock mass. Acconding on the course of quantitative analysis of fault complexity in mine and modern civil engineering at present, single fault complexity coefficient represents various geologic facts, and its value is less than the fact. Based on the evaluation of sheer incline area ratio and strike-slip fault area ratio about former research, measure fault complexity take an inclined fault interval multiply by the sum of extension length and ratio of numerical statement area. By geometric analysis of geological objects, this paper put forward geometric model which represents geological facts in truth. The results show that expression educed from the model has no multiplicity, is transpicuous and convenient for popularizing.

The Influence of Fault Dip Angle on the Floor Fault Activation

In order to study the influence of different fault dip angle on fault activation under different mining conditions, the supporting pressure distribution model of corresponding working face is established and the formula of stress on the fault plane is also derived. Combined with the Mohr-Coulomb yield criterion, the essay summarizes the critical factor of fault rock yield activation. The contributions of fault dip angle and base disturbance to critical factors are further analyzed. At the same time, by using FLAC software, the rules of different inclined fault in mining whose floor of the plastic zone around the propagation and the variation of the stress field characteristics are analyzed. The simulation results showed that connected condition of floor plastic zone and the regularity influence floor water inrush. The research shows: small obliquity faults and shallow area faults are more likely to be activated, and small obliquity faults are more susceptible to affect disturbance leading to the bottom of plastic failure. The results would have an important value to preventing against fault water inrush accident and projecting the waterproof pillar.

GRAVITY ANOMALIES OF A FAULT CUTTING A SERIES OF BEDS

The gravity anomaly due to a single horizontal semi‐infinite block terminated by a vertical or dipping fault has been discussed by several authors previously. Geldart, Gill, and Sharma (1966) gave a new and simple expression for calculating the gravity anomaly due to a block cut by an inclined fault at an arbitrary angle and used this expression to obtain the gravity anomaly due to a fault cutting a single bed. In their derivation the effects of both the upthrown and the downthrown blocks were taken into consideration. It is, however, only in the unusual situation that faults cut a single bed of uniform density. More often, faults cut a series of beds of different densities and thicknesses. If the densities and the thicknesses of the various beds differ greatly, an interpretation based upon replacement of the series of beds by a single bed of uniform density may be highly erroneous. Starting from the single block expression given by Geldart et al, an expression can be derived giving the gravity anomaly due to a fault cutting a series of beds having different densities and thicknesses.