Study On Vertical Bearing Capacity Of Static Pressed Pile On Base Of Index Of Cone Penetration Test

Static pressed pile (SPP), as one kind of precast pile, since its process flowage complies with the demand of safety, civilization and environmental protection, and also that it can be highly informationized in construction, has been used more and more in the engineerings nowadays. The value of the vertical bearing capacity of precast static pressed pile got from the current general ways often have glaring errors, so it is very difficult to guide correctly the engineers on the design and optimization of the pile foundation.Cone penetration test (CPT) method is one kind of ways in calculating the vertical bearing capacity of precast static pressed pile, by which we can collect continuous and highly digitalized data, and also the results of which are seldom affected by personal factor. Considering that the stressed mechanism of CPT resembles the SPP in the rules of load transferring in loading test, also that the result of set is very near to the SPP, we come to a conclusion that set method may be a reasonable, reliable, and an effective method.According to the rules of load transferring and interactional theory between the pile and soil, there are many factors which can affect the vertical bearing capacity of spp. Stratum structure, engineering properties of the foundation soil, and the parameters of the pile may be the main ones. Rock-soil comes from the nature, and the stratum structure and engineering properties of which differ greatly from one area to another area. For different pileparameters, the lateral and end resistance of the pile act differently, correspondingly, the bearing capacity may be very different. So it is very necessary to set up an areal experiential formula in the engineering practice to decide a more precise value of the bearing capacity of the pile.The paper covers the alluvial and diluvial plain of the middle and lower reaches of the Huanghe river in eastern Henan province. Typical stratum structure is widely distributed in this area. Generally, about 20 meters deep Loose'slight state silt is distributed in the upper part of the foundation soil, below which is middle~dense state silty or fine sand. Correspondingly, for the SPP, the lateral soil is silt, and the soil of bearing layer is silty or fine sand. Confined by the ability of the pile when penetrating the soil layer, the length of the pile is about 20 meters, and the ratio of the length to the diameter is about 50. So the studied area can supply typical stratumstructure model and pile parameter model.The main parts of my work are as follows:(1) The paper analyzes and compares the stressed mechanism between the SPP and CPT, concludes five factors which affect the calculating precision. The paper also has a systemic analysis and statistic on lots of collected indoor pile-soil friction test data of the studied area about the stratum structure and parameter model of the pile. The subsoil of the studied area is composed of silt and sand. The stratum structure has a very well permeability and its pore water pressure can vanish very quickly. We can get from the result of indoor tests that the friction relation between the pile and the soil has the characteristic of singleness and linearity. By analyzing all the factors that affect the precision, we know that the scale effect element may be the most important.(2) To evaluate the scale effect, the paper analyzes and compares the actual pressure loaded on the pile of the SPP during the process of loading and the end resistance of the pile calculated from the result of set, and get the general rule of the distribution of scale effect in different area.(3) the paper has the mathematical statistics on the result of loading test of the pile and the result calculated from sct in actual engineering example. On the basis of the formula supplied by 《TECHNICAL CODE FOR BUILDING PILE FOUNDATIONS》, the writer deduces the correction factor and experiential formula fit for the studied area, and also analyzes the relativity and applicability of the formula.(4) At the same time, the paper simply analyzes the...