Research About The Mechanical Properties Of Mu Us Desert Aeolian Sand Foundation

Mu Us Desert is one of China's 12th largest desert,is rich in oil,natural gas,coal and other natural resources.With the deepening development of the western region,the desert area of oil and gas field development,infrastructure,construction and other projects been developed by leaps and bounds,the combination between construction and desert become more and more closely.Building a large number of projects,the region Maowusu special foundation aeolian sand must be systematicly,comprehensively,in-depth understanded,the mechanical properties of the aeolian sand foundation should be realized to explore the scientific and effective approach of foundations.In this paper,based on scientific research projects of Changqing Petroleum Exploration Bureau "Desert Maowusu applications in geotechnical engineering and engineering study" undertaken by Professor Peng Jianbing,Maowusu most common aeolian sand foundation has been systematic,in-depth studied.Different dry density of different water content aeolian sand analog ground has been designed for static load test,the use of 3D-σfinite element software foundation aeolian sand on the numerical analysis,aeolian sand mechanical properties of the foundation was discussed from three aspects:ultimate bearing capacity, additional stress of foundation,deformation destruction.In Maowusu area two most commonly used method for foundation treatment—water-dropping and water-dropping-vibrating have been studied and its mechanism was revealed.Analysising the test results of dry density of the same working conditions of different water content,the water content of aeolian sand foundation bearing capacity of sand particles is the result of capillary action,low water content as the foundation bearing capacity increases with increasing water content and becomes stable,and increment is small,aeolian sand when the water content of less than 10%of ultimate bearing capacity will be increased as the water content was increased,but a smaller increase,when the aeolian sand is greater than 10% moisture content,tend to the ultimate bearing capacity of foundation stable,no longer with the water content increases;Analysising the test results of water content of the same working conditions of different dry density,with the aeolian sand density increases Ultimate bearing capacity becomes strong,however,in the framework of different dry density,ultimate bearing capacity increases have had a clear distinction,When the dry densityρ≤1.53 g/cm~3,the ultimate bearing capacity and the wind a small plot of sand a very small increase in stem density,when the dry density of 1.62≤ρ≤1.54 g/cm~3,the foundation of ultimate bearing capacity of the wind plot sand dry density increases,an increase of large,when the dry densityρ≥1.62 g/cm~3,the foundation of ultimate bearing capacity of the wind density plot dry sand and a significant increase in This is an important way to improve the bearing capacity of Aeolian sand.The real of water-dropping and water-dropping-vibrating foundation treatment is the role of water penetration and saturation of the environment loads in vibration rearrange sand particles,changes in particle contact state(from unstable to stable), so that the overall structure of the foundation from loose to compact to improve the bearing capacity of foundation.In this paper,10 kinds of test conditions on the deformation and damage the foundation form of classification have been analysised,typical working condition in accordance with change in sign of foundation to study the aeolian sand deformation characteristics of foundation settlement.Observating static Load Test of additional stress in the foundation,in this paper,the most typical test conditions-water-dropping secret vibration condition as an example,from different angles detailed analysis the distribution change featurea of eolian sand vertical,horizontal stress,Aeolian sand foundation with the foundation of the vertical depth of additional stress and reduce the increase,decrease stress attenuation, transmission is not with the depth of the upper part of the increase of load;the level of additional stress with the upper part of the load increases.For Maowusu the impact of additional stress areas within the scope of aeolian sand from a single occurrence of a whole constitute a breach of the foundation,which constitute the foundation of aeolian sand shear strength of the impact of the foundation is a major factor in the ultimate bearing capacity.In this paper,3D-σFEM design software for ten aeolian sand foundation for numerical simulation,the vertical,horizontal stress color map,vertical displacement of foundation color map is derived.Foundation study shows that the vertical,the maximum horizontal additional stress and ultimate bearing capacity of the foundation was a good linear relationship.Aeolian sand water content,dry density does not affect the foundation of the proliferation of additional stress in vertical depth,and vertical proliferation of additional stress do not vary with the depth of the upper part of the load increases.The horizontal additional stress influence in junior,basis of lateral deformation of aeolian sand occurs mainly in shallow,based on the edge of aeolian sand under high shear sliding and plastic deformation zone first.Comparatively analysising aeolian sand of the foundation measured the results of additional stress and of numerical results,center for additional stress measured values and calculate values have a good linear relationship with the upper load value,center for additional stress measured value is the calculated value of 2.2～3.6 times.Research shows that aeolian sand foundation deformation modulus is not constant,different density of the deformation modulus circumstances vary significantly,the greater the density the greater the deformation modulus,static load test stroke deformation modulus Sand Sand wind density, water content change.The difference of deformation modulus between static load test of the foundation and foundation used in numerical simulation is the main reason for the big difference of additional stress between the measured value and calculated value.