第四章-工程地质野外试验课件.pptVIP

2. Application of standard penetration test(1) Evaluate the physical state of foundation soil (such as stratum profile and soft interlayers;(2) Evaluate the mechanical property parameters of foundation soil (such as deformation modulus and physical and mechanical property index);(3) Calculate the bearing capacity of natural foundation;(4) Calculate the ultimate bearing capacity of single pile and select the pile tip bearing layer;(5) Evaluate the liquefaction possibility and grade of sand and silt in the site. * 3. Touch rodThe seamless steel pipe with diameters of 40 to 50mm is used in the world, and the engineering geological drill pipe with diameters of 42mm is commonly used in our country, and a hammer pad is set up in the connection with the core hammer.The International Association of Soil Mechanics and Foundation Engineering (ICSMFE) set up a special committee in 1957 to study the standardization of SPTS. In 1988, the proposed international Standard for standard penetration Tests was submitted to the first International Conference on Exploratory Testing, which was adopted in 1989 and started to be implemented. * 2. In order to ensure that the drill pipe does not wobble sideways during hammering, the drill pipe should be checked regularly. The bending degree of the drill pipe should be less than 0.1% and the joint should be firm.3. Adopt the automatic decoupling hammer method to carry out the penetration test and reduce the friction resistance between the guide rod and the hammer. Avoid eccentricity and shaking during hammering, and maintain the perpendicularity after the connection of the penetrator, probe rod and guide rod, so as to keep the hammering ability constant.4. Drive the penetrator vertically into the test soil layer, and the hammering rate should be less than 30 blows /min. First drive 15cm without counting the number of hammer hits, and continue to drive in. Record the number of hammer hits every 10cm driven. The cumulative number of hammer hits