Civil Engineering Blogs

Aim: To obtain subsurface information by undisturbed or disturbed sampling. Apparatus: 1. Tripod 2. Drill rods 3. Hammer of 63.5 kg 4. Samplers Theory: One of the most common in-situ tests is the standard penetration test or SPT and currently the most popular and economical means to obtain subsurface information (both inland and offshore). It offers the advantage of low cost, applicability to many soil types, samples are obtained (although disturbed) and a large database from which many useful correlations have been developed Usually SPT is carried out at every 0.75-m vertical interval or at the change of stratum in a borehole. This can be increased to 1.5 m if the depth of borehole is large. Due to the presence of boulders or rocks, it may not be possible to drive the sampler to a distance of 450 mm. In such a case, the N value can be recorded for the first 300-mm penetration. The boring log shows refusal and the test is halted if: 50 blows are required for any 150 mm penetra...

Aim : To determine ultimate bearing capacity and settlement of soil mass. Apparatus: 1. Typical set up used for gravity loading OR Loading platform truss 2. H ydraulic jack of required capacity 3. Properly calibrated load measuring device, such as pressure gauge, electronic load cell, or proving ring 4. Circular or square bearing plates of mild steel 5. Dial gauges with 25 mm travel, capable of measuring settlement to an accuracy of 0.01 mm. 6. Datum Beam or Rod 7. A ball and socket arrangement 8. Loading columns 9. Steel beams 10. Wooden blocks 11. Collar 12. Reaction girder with cradles Theory: The locations for load test shall be based on exploratory borings, and unless otherwise desired, shall be conducted at an elevation of the proposed foundation level under the worst estimated conditions. In case the water table is within the depth equal to the width of the test plate, the test shall be conducted at water table level. In case water table is higher than t...