Development And Application Of Deep Soil Lateral Load Test Probe

The mechanical parameters of deep soil play an important role in geotechnical engineering design, such as static lateral pressure coefficient, horizontal foundation coefficient, undrained shear strength and bearing capacity and so on. Generally, all the parameters are obtained by indoor soil test and the experience, because of the effect of sampling, transport and indoor test on original soil stress state, make the measured parameters can’t reflect the real condition of field soil. Therefore, seeking a simple in-situ testing technology to estimate the parameters is the right direction of the geotechnical engineer. Currently there three kinds of mature tests are commonly used, they are the flat dilatometer test, pressuremeter test and stress shovel test, but still exist some limitations in the application, it is necessary to improve and develop the existing test instrument to meet the needs of practical engineering. Thus, we made a further optimization design based on the self-developed pore pressure and displacement probe and developed the deep soil lateral load test probe, through the field test, to realize the preliminary application of test results. The main research contents and achievements are as follows:(1) Without changing the specifications of traditional probe, we replace the traditional flexible diaphragm with a micro rigid loading plate and use an elastic rubber diaphragm to seal and reduction it. The lateral displacement of the rigid loading plate can attain 3mm and the relative displacement is 0.05, the complete p-s curve.can be measured in theory. The micro displacement sensor, pore pressure sensor and soil pressure sensor were installed on the probe for measuring the displacement of the loading plate, soil pressure, pore water pressure and the pore pressure dissipation experiment could be carried out also. The associated equipment and principle of the deep soil lateral load test were introduced briefly in this paper.(2) The deep soil lateral load test and the contrast test such as flat dilatometer test and vane shear test were carried out in the soft soil which is of high compression in Lianyungang test site, so were in the overbank silt in Hongqiao test site. The result shows that the deep soil lateral load test can not only accomplish the goals of the traditional flat traditional test, but it can measure in situ static earth pressure directly, so were the complete p～s curve, excess pore water pressure and its dissipation process. The test data can reflect the engineering properties of test soil more fully and directly.(3) According to the experimental data, the methods of classifying soil layer accurately and estimating the parameters simply such as horizontal consolidation coefficient, static lateral pressure coefficient, horizontal foundation coefficient and subgrade bearing capacity and so on were discussed, the good results have been achieved. It can achieve the purpose of a test for multiple parameters and satisfy the requirement of engineering practices.