Research On The Ultimate Bearing Capacity Of The Thin Upper Plate Of Karst Cave Under The Raft Foundation

At present, raft foundation has been widely used in the karst area high-rise buildings.Atthe same time, study on the ultimate bearing capacity of upper plate of Karst cave is veryimportant for engineering construction in Karst areas. This study was based on statisticanalysis of geology data that came from large variety of karst regions especially the north ofGuangdong province. It focused on investigating the main factors affecting the ultimatebearing capacity of the cave roof under raft foundation loading. The influences and their lawswere analysed using the Finite Element Method.The major work of this thesis is summarized as following:On the basis of large amount of available books, papers and geology data, and based onthe field investigation and gathering of the engineering geology data of the north of theGuangdong province, the statistic research of the cave shape, size, distribution, cover depthand limestone characteristics as well as the physical and mechanical properties of theoverlaying soil was emphasized, combined with field testing results. A generalized finiteelement was then proposed. And, by studying the mechanical property of carbonate rock, it isfound that carbonate rock shows elastic-plastic properties.By comparing various methods to define ultmate bearing capacity in and out of China.Proposed use of the finite element software for numerical simulation method to solve the caveroof ultimate bearing capacity. Laws that describe how the ultimate bearing capacity of thecave roof under raft foundation is affected by the thickness of the cave roof, the thickness andmodulus of the covering soil and also the dimension of the raft foundation were investigatedand demonstrated though a good quality of finite element models. Some empirical dataobtained may be in favour of the field practice.This article describes the basic idea of the orthogonal finite element test analysismethods, and apply it to the analysis of the parameters. Then some disciplinary results areachieved. With this method, the orthogonal parameter analysis theory was adopted to analysethe above-mentioned four main affecting factors. and obtain between the various factors thataffect the primary and secondary relationship.Last but not least, the author proposed the summary of the inductive regarding the determination of the ultimate bearing capacity of the cave roof under large scale raftfoundation loading.