1、GEOTECHNICAL SPECIAL PUBLICATION NO. 302 PANAM UNSATURATED SOILS 2017 APPLICATIONS SELECTED PAPERS FROM SESSIONS OF THE SECOND PAN-AMERICAN CONFERENCE ON UNSATURATED SOILS November 1215, 2017 Dallas, Texas SPONSORED BY International Society of Soil Mechanics and Geotechnical Engineering The Geo-Inst
2、itute of the American Society of Civil Engineers EDITED BY Laureano R. Hoyos, Ph.D., P.E. John S. McCartney, Ph.D., P.E. Sandra L. Houston, Ph.D., D.GE William J. Likos, Ph.D. Published by the American Society of Civil Engineers Published by American Society of Civil Engineers 1801 Alexander Bell Dr
3、ive Reston, Virginia, 20191-4382 www.asce.org/publications | ascelibrary.org Any statements expressed in these materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publ
4、ication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. The materials are for general information only and do not represent a standard of ASCE, nor are they intended as a reference in purchase specifications, co
5、ntracts, regulations, statutes, or any other legal document. ASCE makes no representation or warranty of any kind, whether express or implied, concerning the accuracy, completeness, suitability, or utility of any information, apparatus, product, or process discussed in this publication, and assumes
6、no liability therefor. The information contained in these materials should not be used without first securing competent advice with respect to its suitability for any general or specific application. Anyone utilizing such information assumes all liability arising from such use, including but not lim
7、ited to infringement of any patent or patents. ASCE and American Society of Civil EngineersRegistered in U.S. Patent and Trademark Office. Photocopies and permissions. Permission to photocopy or reproduce material from ASCE publications can be requested by sending an e-mail to permissionsasce.org or
8、 by locating a title in ASCEs Civil Engineering Database (http:/cedb.asce.org) or ASCE Library (http:/ascelibrary.org) and using the “Permissions” link. Errata: Errata, if any, can be found at https:/doi.org/10.1061/9780784481691 Copyright 2018 by the American Society of Civil Engineers. All Rights
9、Reserved. ISBN 978-0-7844-8169-1 (PDF) Manufactured in the United States of America. Preface The Second Pan-American Conference on Unsaturated Soils (PanAm-UNSAT 2017) was held in Dallas, Texas, November 12-15, 2017, featuring the latest research advances and engineeringpractice innovations in the a
10、rea of Unsaturated Geotechnics, with a focus on characterization, modeling, design, construction, field performance and sustainability. PanAm-UNSAT 2017 follows a now well-established series of regional and international conferences on Unsaturated Soils, bringing together researchers, practitioners,
11、 students and policy makers from around the world, particularly the Americas. The conference built upon the success of PanAm-UNSAT 2013 (First Pan-American Conference on Unsaturated Soils, Cartagena, Colombia), as well as that of previous conferences on unsaturated soils hosted in the United States,
12、 including UNSAT 2006 (Fourth International Conference on Unsaturated Soils, Carefree, Arizona) and EXPANSIVE92 (Seventh International Conference on Expansive Soils, Dallas, Texas, 1992). Proceedings of PanAm-UNSAT 2017 have been documented in four Geotechnical Special Publications (GSP) of ASCE inc
13、luding Volume 1: Plenary Session Papers; Volume 2: Fundamentals; Volume 3: Applications; and Volume 4: Swell-Shrink and Tropical Soils. Current Volume 3 (Applications) consists of five sections: Section I, General Field Applications, includes 11 papers dealing with case histories of geotechnical str
14、uctures constructed in the field and field measurements of different variables relevant to unsaturated soil mechanics. Field situations investigated include embankments, slopes, and pan lysimeters. Field testing approaches include interpretation of cone penetration testing in unsaturated soils, and
15、monitoring of variables such as the suction, degree of saturation, effective stress, temperature, earth pressure, and creep displacements. Section II, Stability of Unsaturated Slopes, includes 10 papers dealing with the performance analysis and design of slopes and excavations involving unsaturated
16、soils. Seasonal effects on slope stability and triggering mechanisms are described, as well as consideration of probabilistic analyses, reliability, and risk evaluation. Section III, Pipelines and Transportation Infrastructure, includes 5 papers dealing with analyses of pipelines and roadways involv
17、ing unsaturated soils. One paper on pipelines focused on uplift effects and movement of pipelines in unsaturated soils, focusing on the deformation response of this challenging topic. The four papers on transportation involve evaluation techniques for pavements on unsaturated soils, as well as analy
18、ses techniques for evaluating the deformation of roadways on expansive soils. 3DQ$P8QVDWXUDWHG6RLOV*63 LLL$6 Daichi Hazama2; and Ryunosuke Nose3 1Dept. of Civil and Environmental Engineering, Kindai Univ., 3-4-1 Kowakae Higashi-Osaka 577-8502, Japan. E-mail: kkawaicivileng.kindai.ac.jp 2Dept. of Civ
19、il and Environmental Engineering, Kindai Univ., 3-4-1 Kowakae Higashi-Osaka 577-8502, Japan. E-mail: 1210380029a kindai.ac.jp 3Dept. of Civil and Environmental Engineering, Kindai Univ., 3-4-1 Kowakae Higashi-Osaka 577-8502, Japan. E-mail: 1210380098y kindai.ac.jp Abstract In this study, air pressur
20、e behavior within an earth structure was investigated through a full-scale embankment test. The road embankment (2 m height) was constructed on low-permeability soil and measurement devices (tensiometers, air pressure meters, and soil moisture meters) were installed. The embankment was exposed to na
21、tural conditions, such as rainfall and evaporation, and vehicle weight was applied. Characteristic behaviors of water and air pressure were observed throughout the 1-year monitoring period. Water pressure increased under rainfall and kept decreasing due to evaporation without rainfall. The infiltrat
22、ed rainwater flowed toward the slope toe. Consequently, water pressure at top of the slope increased due to rainfall and decreased soon after rainfall stopped; while pressure at the slope toe started decreasing after a period of time. Conversely, air pressure increased under only heavy rain. Moreove
23、r, it decreased to a point lower than atmospheric pressure following the heavy rain and recovered after a brief interval. INTRODUCTION Concentrated heavy rainfall frequently occurs and triggers landslides. As the area affected by rainfall is fairly localized, it is difficult to predict when and wher
24、e slope failure will occur. Civic awareness about slope failure disasters should be increased to reduce human damages. In this regard, understanding precursory phenomena for landslides is effective. There are a lot of successful cases in which precursory phenomena act as an alert. However, some of t
25、hese phenomena are difficult to explain 3DQ$P8QVDWXUDWHG6RLOV*63 $6 and Gerald A. Miller, Ph.D., P.E.2 1Staff Engineer, Midwest Engineering and Testing Corporation, 2025 S Nicklas Ave., Oklahoma City, OK 73128. E-mail: rodneycmetco.us 2Professor, School of Civil Engineering and Environmental Science
26、, Univ. of Oklahoma, 202 W. Boyd St., Room 334, Norman, OK 73019. E-mail: gamillerou.edu Abstract The cone penetration test (CPT) can be used to estimate soil type using empirically developed classification charts. For the most part, these classification schemes involving tip resistance and skin fri
27、ction measurements have proven quite reliable; however, their applicability to unsaturated soils is questionable. This paper presents results of cone penetration testing in unsaturated soils obtained from two different test sites containing fine-grained soils of low to high plasticity. Analysis of t
28、hese data indicate matric suction can have a significant impact on CPT-based soil classification. Additional data obtained from previous studies and collected from the literature are used to demonstrate the impact of matric suction on CPT test parameters for a broader range of soil types including l
29、ow to high plasticity fine-grained soils and sands. A preliminary framework for developing a CPT classification system for unsaturated soils that considers suction is presented. INTRODUCTION The cone penetration test (CPT) is one of the most useful in situ soil tests for geotechnical engineering. It
30、s usefulness comes from its ability to “rapidly” test to great depths and provide near continuous indications of soil stratigraphy without collecting and testing samples in a lab. One primary application of the cone penetration data is soil classification (e.g. Robertson et al. 1989) using tip resis
31、tance and friction ratio. The tip resistance is derived from the force of soil on the tip of the cone during penetration. The friction ratio is determined by measuring the sleeve friction on the shaft of the cone and dividing by tip resistance. The tip resistance can also be normalized by overburden
32、. Together, tip resistance or normalized tip resistance and friction ratio can be used to determine soil type using an empirically derived method. In saturated soil profiles, the addition of pore water pressure measurements can be used to refine soil identification procedures. Classification schemes
33、 based on the CPT have proven robust and reliable for cohesionless and saturated soil profiles. However, there is a lack of information regarding applicability to unsaturated soils. This paper investigates the application of CPT-based classification to unsaturated soils and lays the groundwork for d
34、eveloping a CPT-based method of interpretation for unsaturated soil. This preliminary framework for soil identification is based on results from CPT tests at two fine-grained field sites, and data from the literature involving different soil types. The results indicate potentially useful relationshi
35、ps between CPT parameters, soil types, and matric suction. 3DQ$P8QVDWXUDWHG6RLOV*63 $6 however, none of this work has moved far enough to be generally applicable in practice. SITE DESCRIPTION Two field sites with relatively uniform soil stratigraphy close to the University of Oklahoma were chosen fo
36、r this research. The sites are referred to as North Base, and Goldsby. The North Base site was located west of the Max Westheimer Airport in Norman, OK (latitude: 35146.58“N, longitude: 972746.39“W). The soil profile at the site varies between low and high plasticity soil with soil plasticity greate
37、r near the surface. A water table was found to fluctuate between depths of 8.0 to 9.0 feet. This water table was likely the result of transient flow of seasonal moisture rather than a natural aquifer. The majority of material found at North Base is considered fine-grained; however, there were rock i
38、nclusions found near 9.0 feet. The Goldsby site was located near Goldsby, OK approximately 5 miles south of the University of Oklahoma (latitude: 35 920.61“N, longitude: 972840.04“W). The soil profile contains low plasticity clay for 10.0 feet, which was the depth of interest for this investigation.
39、 There was no water table encountered at Goldsby. CONE PENETRATION TESTING The Oklahoma Department of Transportation (ODOT) performed cone penetration tests at both Goldsby and North Base with assistance from University of Oklahoma researchers. Three test soundings were obtained per site visit. The
40、cone was pushed to a depth of approximately 10 feet for each sounding. Thirty-nine cone soundings were conducted over the course of this study. The CPT was run in general accordance with ASTM standard D5778-12, with a penetration rate of approximately 0.73 in. /sec. using a standard cone with a 60-d
41、egree apex conical point having a projected tip area of 1.55 in2, and a friction sleeve just behind the cone with an area of 23.3 in2. Electronic signals from the tip and sleeve load cells were collected with a data acquisition system and used to compute tip resistance and skin friction. RESULTS AND
42、 PRESENTATION OF PRELIMINARY INTERPRETATION METHOD To illustrate the influence of matric suction on CPT parameters, results obtained on two days with different soil moisture conditions are compared. Figure 1 presents the results of CPTs performed on 7/29/2013 and 9/10/2014 at Goldsby. The moisture c
43、ontent, interpreted matric suction, tip resistance, and sleeve friction profiles from the tests are presented in the figure. Matric suction was estimated using field moisture contents and soil water characteristic curves developed using pressure plate testing and a WP4 chilled mirror device as prese
44、nted in Collins (2016). Looking at depths above 5-feet, the water contents on 7/29/2013 were comparatively lower than those for the test conducted on 9/10/2014, and thus these will be referred to as “dry” and “wet” tests, respectively. The tip resistance values measured during the “dry” tests were o
45、n 3DQ$P8QVDWXUDWHG6RLOV*63 $6 however, trends are relatively consistent. Figure 1: CPT from “wet” and “dry” test dates for Goldsby M ois tureC onte nt(%)10 15 20 25Depth(ft.)0246810M atri cS ucti on(psi)0 100 200 300 400T ip R esi stan ce ( tsf)0 20 40 60 80 100 120S leev e F ric tion (ts f)0 1 2 3
46、4 57 / 2 9 / 2 0 1 3 - “ w e t “9 / 1 0 / 2 0 1 4 - “ d r y “3DQ$P8QVDWXUDWHG6RLOV*63 $6&(The CPT from North Base on two different dates is shown in Figure 2. The results are comparable to Goldsby where on the “dry” date the tip resistance is higher and the sleeve friction is lower compared to the “
47、wet date”. The possible hysteresis effect observed at Goldsby is not noticeable in the North Base data. This may be because the soil was tested on wetting days at Northbase, so because the data falls on the same wetting curve, the hysteresis is not noticeable. Figure 2: CPT from “wet” and “dry” test
48、 dates for North Base In Figures 1 and 2, the friction ratio is observed to vary over significant portions of the soil profile where suction changes are greatest. This variation in friction ratio can lead to different interpretation of soil type for the same soil layers depending on the moisture level. For example, using a popular correlation by Robertson (1989), for a depth of 3.0 feet in Figure 1, the interpreted soil type based on tip resistance and friction ratio leads to a soil type description of M o is tu reC o n te n t(% )10 15 20 25 30 35 40Depth(ft.)0246810M a tric
