Study On The Softening Of Cretaceous Mudstone In Changchun Area

In the Changchun area,there is a layer of Cretaceous mudstone with a thickness of about 20m,which is often used as the foundation for many tall buildings.As the foundation of the Cretaceous mudstone,there will be problems of water softening,that is,the bearing capacity is reduced and the settlement is increased.However,for many years,the experimental study on the influence of mudstone on the bearing capacity of the foundation after the lack of water in the Changchun area,in order to study whether the Cretaceous mudstone softens after water contact and the impact on the bearing capacity of the foundation after water contact,this paper has carried out theoretical and experimental aspects the studyThe research work aims to make up for the lack of water softening test research work of the Cretaceous mudstone in Changchun,and to provide reference technical parameters for geotechnical investigation,design and construction in Changchun.Firstly,the research status of mudstone softening and foundation bearing capacity at home and abroad was investigated.Secondly,the geological environment of Changchun area and the distribution of Cretaceous mudstone were deeply studied.Then the theory of foundation bearing capacity and its related calculation methods were summarized and summarized.The mud rock was subjected to the plate load test and the in-situ shear test before and after the water contact.Based on the test results,the changes of the bearing capacity and settlement of the Cretaceous mudstone before and after the water contact were analyzed,and the Cretaceous mudstone in Changchun area was obtained There is a softening conclusion,and the characteristics of softening of mudstone are manifested in the increase of foundation settlement and the reduction of foundation bearing capacity,and give the proportion;finally,using the shear strength index of in-situ shear test as a parameter,FLAC3D is limited.The differential software numerical simulation is used to establish the model of the mudstone foundation before and after the water,and the cloud map and load-settlement curve of the Cretaceous mudstone foundation settlement under different loads are obtained.The load-settlement curves obtained from the plate load test and the numerical simulation test are compared.analysis.Finally,it is concluded that the field plate load test can better reflect the bearing capacity of the cretaceous mudstone in changchun area before and after water immersion,and the sedimentation of the cretaceous mudstone increased by about 2.5% after water contact,and the characteristic value decreased by about 30% after water contact.It is of certain significance to study the water softening and bearing capacity changes of the Cretaceous mudstone in Changchun in the future.