Application And Regularity Of Pressure Test In Expansive Soil

The pressure test is a lateral load test performed in a borehole.The principle is that by pressurizing the side pressure device,the elastic film is expanded in the vertical hole,and the pressure is transmitted to the surrounding soil uniformly,so that the soil of the hole wall is deformed radially until it is destroyed.The side pressure test mechanics model is usually regarded as the axisymmetric plane strain problem,and the test results are reflected in the modified side pressure curve.The related mechanical and engineering property indexes of the foundation soil can be obtained through the side pressure curve.The side pressure instrument was invented by Menard in 1956,and the side pressure test has developed a relatively perfect theoretical system in the development of these decades,and has achieved fruitful results in engineering practice.The physical and mechanical properties of deep soil are proved by side pressure test.Compared with the standard penetration test and the static contact test,the pressure and volume change of the cylindrical cavity in the whole process of the expansion were obtained.The more specific geological description of the formation can be compared with the static contact and dynamic contact,which is not enough attention.The application of the pressure test in expansive soils in Guangxi is relatively rare.This time,the pressure test and other in-situ tests were conducted on the expansive soils of Ningming,Baise,and Nanning in Guangxi,and the expansion was based on the existing side pressure test theory.The ground pressure test curve of the ground was analyzed.From the side pressure curve,the bearing capacity and deformation modulus of the foundation,the shear strength parameter of soil,the cohesion force of the soil,the angle of the internal friction and other mechanical and engineering properties were deduced,and other in-situ tests:static penetration test,Standard penetration tests,soil in-situ shear tests,load tests,and corresponding indexes obtained from laboratory tests were analyzed to arrive at the conclusion that in several in-situ tests,standard penetration tests and static penetration tests are not applicable.Some empirical tables and formulas are used to calculate the bearing capacity of the expansive soil foundation.The bearing capacity and load test of the expansive soil foundation calculated by the side pressure test prefabrication method are the closest.The load test is considered to be the most accurate and reliable method for determining the bearing capacity of the foundation.Therefore,the use of a side pressure test to determine the bearing capacity of the expansive soil base in the three regions has a high reference value.The regression equations were established by using the standard penetration test results of the number of hits N and the static penetration test ratio penetration resistance p_s and the bearing capacity of the ground pressure test acquired by the plasticity method,and the correlation was good.The former two were in situ.The test index can be transformed with the bearing capacity obtained by the side pressure test.The parametric pressure-deformation parameter G_m obtained by the pressure test and the deformation modulus E₀ obtained by the load test establish a regression equation with good correlation.In the absence of a load test,the regression equation can be used to determine the soil using a pressure test.Deformation modulus.The side pressure test calculated that the internal friction angle error of expansive soil is larger.