Study On Effects Of Sampling Disturbance In Port Prospecting At Hainan Province

Engineering prospecting is the premise for engineering design and construction, sampling is the important method to get the engineering properties of soil. Due to the restrictions of development in industry and technology, prospecting equipment and sampling method used in engineering prospecting have no big changes in recent decades. With the high requirement to obtain the engineering properties of undisturbed soil in modern engineering, the contradiction between sampling technology and construction is more and more obvious. The disturbance on the soil in-situ is different as the different sampling methods and sampling equipment, thus the effects on soil engineering properties is different.The paper began at the current prospecting sampling profile in domestic and foreign, combining with soil sampling in port prospecting, analyzed and studied the common problem in engineering prospecting, including the mechanical analysis and test strength parameter of different samplers. Analyzed the sampling disturbance problem in clay soil from sampler types,diameter and sampling depth :1,Analyzed the effects of disturbance on physical and mechanical parameters between heavy hammer-less blow sampler and rotation-static pressure sampler. By comparing the disturbance on soil engineering properties caused by rotation-static pressure sampler is bigger than heavy hammer-less blow sampler, some of the mechanical parameters is more than 20% difference; Through the analyzing soil unit found that the effect on compression strain increase is large when the angle of sampler below 10o.2,Analyzed the disturbance on soil of two kinds of diameter samplers 70mm and 100mm, the difference of test parameters, using disturbance index and volume strain methods to analyze and evaluate the disturbance. Despite the band of disturbance is increasing as the diameter increasing of sampler, the large diameter sampler is great advantage than small diameter in deep sampling;Through the analyzing soil unit found that the effect on compression strain increase is large when the area ratio is below 0.4. 3,From theory to analyze the disturbance of different depth sampling as removing pressure, analyzing the stress-strain status and mechanism of disturbance in different depth, and the influence to soil engineering properties of different consolidation. Through mathematical relationships, found the methods to predict soil engineering properties of different consolidation status.Soil disturbance is inevitable, We must evaluate the status of disturbed samplers to improve the quality of engineering prospecting. Combining with the evaluation methods for disturbed samplers, pointed out the significance of disturbance evaluation and pretreatment to samplers. Finally based on the evaluation of soil disturbance, analyzed the method of soil pretreatment, pointed out the strength relationship of equivalent consolidated and Ko consolidated. This paper also proposes some methods and measures to reduce the soil disturbance.