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1、Chap. 4Subsurface Investigation and Characterization4.4 A two-story reinforced concrete building is to be built on a vacant parcel of land. This building will be 100 ft wide and 200 ft long. Based on information from other borings on adjacent properties, you are reasonably certain that the soils bel
2、ow a depth of 5 to 8 feet (1.5 to 2.5 m) are strong and relatively incompressible. However, the upper soils are questionable because several uncompacted fills have been found in the neighborhood. Not only are these uncompacted fills loose, they have often contained various debris such as wood, rocks
3、, and miscellaneous trash. However, none of these deleterious materials is present at the ground surface at this site.Plan a site investigation program for this project and present your plan in the form of written instructions to your field crew. This plan should include specific instructions regard
4、ing what to do, where to do it, and any special instructions. You should presume that the field crew is experienced in soil investigation work, but is completely unfamiliar with this site.SolutionBased on available information, the site may be underlain by 5 to 8 ft of uncompacted fill over strong s
5、oils. To investigate this site, we should do the following:1. Perform five cone penetration tests, one at the center of the site and one near each of the four comers of the site. Each CPT should reach a depth of at least 25 ft.2. Drill 10 to 15 borings, with locations spread out evenly around the si
6、te. Each boring should reach a depth of at least 25 ft. Perform standard penetration tests at 5-ft intervals4 Obtain modified California samples of the strong soils at various depths.Solutions Manual4-4Foundation Engineering: Principles and Practices, 3rd Ed4.6 Standard penetration test was performe
7、d in a 150-mm diameter boring at a depth of 9.5 m below the ground surface. The driller used a UK-style automatic trip hammer and a standard SPT sampler. The actual blow count, N, was 19. The soil is a normally consolidated fine sand with a unit weight of 18.0 kN/m3 and D.o = 0.4 mm. The groundwater
8、 table is at a depth of 15 m. Compute the following:a. Mob. M,60c. Drd. Consistency (based on Table 3.3)e. WSolutiona. Using Equation 4.11, compute0.73(1.05)(1.00)(1.00)(19) 睥=240.60b. Using Equation 4.12, computeM/24100 kPa(18.0 kN/m3)(9.5 m)=18e) 2016 Pearson Education, Inc., Upper Saddle River, N
9、J. All rights reserved. This publication is protected by Copyright and written permission should be obtained frorrthe publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying,Use Equations 4.28, 4
10、,35, 4.36, 4.37, and 4.38 to compute DrD,.=60 + 251og(0.4) 1.2+ 0.05 log181000)0.47(100)(22 6)亟 xl00%9.5(18.0)= 50%d. Medium dense e. Per Figure 4.30,敢=37Solutions Manual4-6Foundation Engineering: Principles and Practices, 3rd Ed4.9 The following standard penetration test results were obtained in a
11、uniform silty sand:Depth (m)1235Mo12131815The groundwater table is at a depth of 2.5 m. Assume a reasonable value for y, then determine(pf for each test. Finally, determine a single design value for this stratum.SolutionPer Table 3.2, assume y values of 17 kN/m3 above the groundwater table and 20 kN/m3 below the groundwater table. Note that any reasonable assumptions for y would be acceptable.Depth (m)1235crt (kPa)1734486812131815pNA404440Use 武ave = 41Solutions Manual4-10Foundation Engineering: Principles and Practices, 3rd Ed
