Research On Stability Of Thick Quaternary Quicksand Stratum

Thick quaternary quicksand is a special strata encountered in Sinking and DrivingEngineering. A lot of accidents were happened in that strata when shaft engineering working,such as the shaft lining ruptured, gushing sand. What is more, it easily leads to the largesurface area of the collapse, the surface buildings damaged cracking. In this paper, theprospecting shaft of manganese and lead-zinc mine in Gansu Province is studied combinedwith theoretical analysis and numerical simulation. Several research projects are setted up,including the shaft fracture mechanism, supporting scheme of thick quaternary quicksand andsecurity and stability system of shaft lining. Main contents are described as follows:（1）Based on the elasto-plastic analysis of the shaft lining, the elasto-plastic limitbearing capacity under Interaction between borehole surrounding rock and supporting isderived. Through analysising of the rupture characteristics of the shaft lining, the externalreveal law and the development law of internal rupture surface are obtained. The geotechnicalmechanical testing data of ore strata offered by corporation, using the way of engineeringtreatment, the rock physical mechanical parameters of the quicksand, two-mica quartz schist,dolomitic marble are obtained.（2）By comparing the Flac3Danalysis of the numerical simulation of the3#explorationmine shaft collapse accident and engineering practice, the shaft deformation and failure areanalysised. The internal and external reasons of fracturing of shaft lining are the liningstructure supporting strength insufficient and flow plastic, instability of the quaternaryquicksand.（3）The well construction of prospecting shafts is controduced, four kinds ofstrengthening utilization schemes are proposed. Reasonable options are obtained by Flac3D.Using the way of AHP and fuzzy comprehensive evaluation, the shaft security stabilityevaluation system is built. By calculating the weight of influencing factors, it is known thatthe shaft thickness, shafr strength parameters, construction input costs and the shaft structure are prior. The performance of supporting scheme can be assessed.（4）Catastrophe theory is introduced to study the shaft stability. Catastrophe model ofshaft fracture is established to analysis the control variables and state variables of shaftdeformation and the critical pressure from the energy point of view. The formula has beendeduced for the applicability of the optimum scheme.