唐山市地下岩体破裂分析

FRACTURE ANALYSIS OF UNDERGROUND ROCKS IN TANGSHAN CITY

地下岩体破裂是影响城市安全与地下工程建设的主要因素之一,地下岩体破裂分布预测对城市规划具有重要意义。以弹性力学理论为研究基础,运用有限单元法,对唐山市的构造应力场进行了计算,介绍了计算模型和模型参数的确定:根据格里菲斯准则,进行地下岩体破裂区预测,同时,对计算结果进行了分析,并对城市规划和防灾减灾问题做了初步探讨,提出了几点结论和建议。

Fracture in underground rocks is one of the main reasons to affect city safety and underground engineering construction,and the prediction of fracture distribution in underground rocks is very important for city planning.Research on the distribution and mechanism of the rock fracture is the key of disaster prevention and mitigation.In Tangshan city,the big earthquake in 1976 is still remained freshly in people's memory,which caused 240 000 lives lost.Fracture distribution investigation of underground rocks and city planning have been paid more attention and recognition by many researchers.Based on elastic mechanics and finite element method, the tectonic stress field of Tangshan city is calculated and analyzed,and calculating model and parameters of the model are presented.Firstly,six faults are considered as a kind of material,and other part of the region as 5 kinds of material according to different rock geology conditions.The five kinds of material are Permian shale,Jixian period dolomite,Ordovician lime stone,Cambrian lime stone and sand stone.Fault is taken as a special material with appropriate mechanical characters.All elements are treated as triangular shell elements,and there are 144 nodes,251 elements in the region.The matrixes D of all kinds of materials are calculated,and stress and energy distribution are solved.Research area includes centeral,Fengrun,Dongkuang districts and Fengnan county of Tangshan city.This area includes Dabalizhuang fault,Dachengshanbei fault,Tangshan fault,Douhe fault, Beiziyuan anticline fault and Kaiping syncline fault.The applied force on the model is simplified to concentrical forces.According to Griffith's criterion,the fracture distribution of underground rocks is predicated.The calculating results are analyzed and some suggestions for city planning,disaster prevention and mitigation of Tangshan city are given.