Site and Geomaterial Characterization

Geotechnical engineering has evolved over the past half century from a soil mechanics and foundation engineering based component of civil engineering to a field with many subdisciplines that provide earth system information, data, analysis, design, and construction services required to meet a broad range of societal and environmental needs. The current status of the discipline is assessed, major unresolved issues are identified, and challenges that must be addressed in resolving these issues, as well as to enable development of new and better geosolutions are indicated. The promise and potential for new and emerging technologies - biotechnology, nanotechnology, sensors technology, geophysical and remote sensing methods, and information technology - are discussed.

The Chi Chi earthquake of September 21, 1999 triggered extensive soil liquefaction in Central Western Taiwan. The majority of the sand deposit in this region had significant amounts of fines. The back analysis of liquefaction potential for the sand deposit in this region using standard penetration (SPT), cone penetration (CPT) and shear wave velocity (Vs) test vales yielded contradicting results. The authors performed a series of CPT chamber calibration tests and cyclic triaxial tests on remolded Mai Liao Sand (MLS) with various fines contents and densities. With these data, the authors were able to calibrate the correlations between CRR and q_c for MLS. This paper describes the geological background of MLS, the laboratory calibration tests and their implications in the assessment of liquefaction potential for MLS.

The use of the piezocone test (CPTU) for geotechnical site investigation offers direct field measurements on geostratigraphy and soil behavior. Its execution time is much less in comparison with the conventional drilling and sampling procedures commonly used in Mexico and offers a great opportunity to accelerate the field jobs, thus reducing operation costs. Recently, these tests were used in a broadly explored area in the soft lacustrine deposits of Mexico City Valley. In this paper, geotechnical design parameters obtained from CPTU tests (q_T, f_s and u₂) and dissipation tests are evaluated for the lacustrine clays of this area, using methods based on cavity expansion theory (CE) and critical state (CS), and placed in comparison with the results of laboratory tests on undisturbed soil samples.

Hydraulic conductivity is one of the major geotechnical parameters that govern the pore water flow characteristics of soils. Determination of hydraulic conductivity, however, is traditionally time consuming and expensive. This research proposes an easy and economical way of determining the hydraulic conductivity from Piezocone penetration tests. High excess pore pressures observed in clayey soils and low excess pore pressures observed in sandy soils during Piezocone penetration tests exemplify this concept. The works of Voyiadjis and Song provide theoretical bases for the estimation of the hydraulic conductivity in this study. This research performs numerical studies and investigates the relationships between the penetration excess pore pressure and the hydraulic conductivity for various soils, and tries to develop easy-to-use equations to detour computational difficulties.

Texas cone penetrometer (TCP) works on dynamic driving principles similar to of SPT, where a hammer is used to drive the cone device to a penetration of 12 inches. Results are typically reported in number of blows to drive 12 in. penetration depth (N12). Current correlations between N12 and soil strength properties are used to determine in situ shear strength properties of soils for geotechnical infrastructure design. Based on the data available, there is a research need to develop new relationships for TCP based on geology and stress histories. This paper presents new correlations development based on the data available in Dallas and Beaumont districts in Texas. In these relationships, undrained shear strength of CL clay is correlated to the depth and N12. Verification studies are conducted to assess the effectiveness of these new correlations.

The cone penetration test (CPT) is a reliable in situ test method for rapid and economical characterization of sites. This paper presents some of the recent advances in CPT for site characterization. Several sampling and sensing techniques have been integrated with the versatile cone penetrometer technology. These include a miniature camera for visual identification, and various sensors for measuring stresses, pore water pressure, shear wave velocity, electrical conductivity, temperature, pH, oxidation-reduction potential, radioactivity, and hydrocarbon contamination in soils. Recently an in situ Electronic Nose-Membrane Interface Probe (EN-MIP) was developed for rapidly sniffing and identifying subsurface contaminants. This innovative EN-MIP system was successfully tested at a gasoline-contaminated site.

The PiezoCone Penetration Test (PCPT) consists of pushing a cone penetrometer with a pore pressure sensor into the ground to obtain soil engineering properties. By using the PCPT, one can develop not only a better understanding of the soil stratification, but also understanding of soil behavior parameters related to soil compressibility as well as predict soil strength. Extrapolation of the PCPT dissipation data on an inverse time scale (1/t method) for estimating the in-situ pore pressure from an incomplete dissipation record has been used by researchers. However, no case study has been reported in open literature in which this methodology has been applied to estimate the status of consolidation of the soil deposit. In this paper, the 1/t method was verified using dissipation data from rigorous calibration chamber tests and field tests.

It is expected that the measurements of tip resistance will be different between vertical cone penetration tests and inclined cone penetration tests. In this paper, a cavity expansion model was first proposed to theoretically compare the different measurements at different penetration orientations based on initial stress anisotropy. Then a field testing program was performed in three different locations with varying soil characteristics in Louisiana. It was found that, the coefficient of lateral earth pressure at rest, K_o, which indicates the degree of initial stress anisotropy, governs the relative magnitude of tip resistance measurements at different penetration directions. The tip resistance tends to increase for K_o less than 1 or decrease for K_o more than 1 as the orientation of penetration changes gradually from vertical to horizontal.

The design and functionality of optical sensing for distributed measurement of water content in soil and strains in geosythetics are presented. Sensing is based on the characteristics of Brillouin scattering at discrete positions along a single optical fiber embedded in the geomedia. The bare fiber is used in strain measurements and it is coupled with a hydrophilic polymer in water content measurements. Experiments with a prototype water content sensor demonstrated measurement of water-content up to 30% in compacted wet clay. Swelling and drying of the polymers showed that the water-content measurements were fully reversible. Experiments with an instrumented PVC geosynthetic strip showed strain measurements to be possible up to the breakage strain of the fiber (~3.5%) over its one-meter gauge length.

This paper proposes practical uses for soil stiffness gauge and dynamic cone penetrometer in earthwork quality control and structural design property development. The recommendations for the interpretation of the measurements made by these equipments for these purposes are presented with an example for the subgrade of a flexible pavement structure.

X-ray computed tomography is a powerful technique for non destructive evaluation of the internal structure (fabric) of geomaterials. Although valuable information can be learned from computed tomography images, several issues have to be considered when performing a quantitative analysis of CT data to avoid misinterpretation of the results. This paper presents some of the issues that can cause a change in CT numbers that is not caused by an actual variation in the density or attenuation of the scanned object. The geometry of the scanned object and the surrounding materials play an important role in the quality of computed tomography images. Artifacts like beam hardening and partial volume effects should be carefully evaluated, and, if possible, minimized to be able to perform a meaningful quantitative analysis of the CT data.

The non-destructive nature of CT scanning allows the same soil sample to be scanned multiple times. Because the soil structure is not affected by the procedure, CT scanning provides an opportunity to investigate particle and pore characteristics at any time and location within a soil sample. High quality digital images can be obtained of soil microstructure during loading or during environmental changes, such as fluctuations in temperatures or moisture. Non-destructive systematic test methods are described for quantifying microscale measurements of scanned digital images using x-ray computer-aided tomography (CT). Tomographic analyses conducted on six different soils indicate that x-ray CT technology provides a viable means for nondestructively observing and measuring grain size distribution, pore characteristics, and pore size distributions of granular soils.

This paper presents the void distribution of saturated specimens of Ottawa sands. The water inside the sand specimen is captured using the Magnetic Resonance Imaging (MRI) technique. The image of water provides the void distribution of the sample. The specimens were prepared in a non-metallic triaxial cell and saturated for at least 24 hours. Then, the specimen was put inside a MRI apparatus. Two sample preparation methods (wet-tamping and dry-pluviation) were used to illustrate the uniformity of the sample. The void distribution along different directions at different locations was calculated. The result indicates that the specimen prepared by dry-pluviation is more uniform than that prepared by wet-tamping. The void distribution of a sample at different stages subjected to the conventional triaxial compression loading was included. The result demonstrates the feasibility of using MRI technique to examine the void distribution of a granular material.

Uniaxial compression tests on specimens with different water content were carried out for the purpose to investigate damage mechanical properties of red sandstone in Hongshanyao hydro-junction Project. Cracks on the surface of specimen were observed and recorded simultaneously with deformation response. With the help of the image analysis, the evolution of surface cracks was obtained. Two different measures were taken to obtain the damage measurement of cracks of specimen surface. Experimental and theoretical analyses were done to explain the intrinsic relation between crack propagation and non-linear deformation.

This paper presents a series of sandbox tests of large deformation in Toyoura sands. The image analysis software package GeoDPDM, which was developed by the authors, is used to investigate the shear patterns and the evolution of the local deformation in sands under different confining pressures. The results show that: (1) The deformation zone looks like fusiform, and can be divided into a number of large deformation bands and small deformation blocks between the bands, (2) The intense shear deformation zones migrate during shearing, (3) The shear strain continues to develop at high rate in the final shear bands, and (4) The soil deformation can be classified into three stages: initial stage of elastic deformation in the whole specimen, middle stage of elastic deformation in localized regions, and the final stage of plastic deformation in the final shear band.

Digital photogrammetry is a low cost, non-contact technique that uses digital imagery to make high resolution, three-dimensional measurements of objects and surfaces. This paper reviews the principles of digital photogrammetry and explores the use of this tool for geotechnical engineering, with an emphasis on the measurement of physical models. The primary goals of this research were to investigate the effects of number of images and resolution on the accuracy of photogrammetric measurements, and to develop guidelines for the use of photogrammetry in geotechnics. This investigation will show that the optimal number of photos for a 3.34 mega-pixel resolution camera is 12, and corresponding error values can be anticipated at approximately 7.5 parts per thousand. There are numerous practice- and research-related geotechnical applications of this technique including landslide monitoring and mapping, measurement of physical models (e.g. centrifuge, shaking table models), and rapid post-earthquake reconnaissance surveys of damage sites.

Many investigations have been made over the past several decades of the electrical conductivity and dielectric properties of soils. Fundamental studies of the physics and chemistry of electrical flows have been used to deduce details of soil microstructure and the properties and interactions between pore fluid and soil particle surfaces. Values of electrical conductivity, permittivity and changes in dielectric properties over frequency ranges of a few Hz to several GHz have been determined and correlated to properties of geotechnical interest. Based on a critical review of available information, the reliability of non-destructive electrical measurements in soils was examined. In particular, the mechanisms for dielectric loss with increasing frequency, and theoretical and empirical correlations with water content, density, void ratio, soil specific surface area, compressibility, and swelling potential were assessed. The results of this review enable some assessments of the strengths and limitations of electrical response measurements as a basis for soil characterization and geotechnical property quantification, and suggest research directions to improve the usefulness of these methods in the laboratory and in the field. In addition, if properly determined and interpreted, the results of electrical response measurements over the kHz to GHz frequency range can provide insights into the causes of time-dependent changes in soil properties.

Soil engineering classification, which is based on particle size distribution and index properties, is important for various engineering activities. The differences in soil types are largely attributed to the differences in the strength of soil-water interaction. The conventional approach generally requires sampling and laboratory testing. Under some situations, crude estimation of soil type is sufficient. A technique that provides fast and reliable in situ estimation of soil type is advantageous for this purpose. This paper introduces a method to estimate the bound water relaxation frequency and subsequently the soil type from Time Domain Reflectometry (TDR) measurements. The approach is based on treating the TDR system as cascade of different low pass filters where the filter representing the measurement probe surrounded by soil has the smallest bandwidth. From this, the bound water relaxation frequency can be estimated. The amount of bound water in soil is related to the soil particle sizes or the specific surface. The relaxation frequency is related to the extent of soil particles-bound water interactions. Typically, the stronger the soil particle-bound water interactions, the lower the relaxation frequency of the bound water. Several benchmark soil materials were evaluated using this approach and the results were satisfactory. Work will continue to further validate and refine this method.

Scour poses severe threat to bridge service conditions. The function of bridge piers and abutments might be significantly impaired due to extensive scour. Field monitoring of the scour process is important for studying scour mechanism, improving pier design, planning effective remediation measures, and deploying emergency warning systems. The current tools for bridge scour monitoring are generally not satisfactory for these purposes. This paper introduces an automatic scour monitoring system using Time Domain Reflectometry principle. The TDR sensor probe was designed by Yankielun and Zabilansky. Experience indicated that some TDR systems are sufficiently rugged for field installation and monitoring. This paper discusses the efforts toward developing a fully automatic scour monitoring system. An algorithm was developed to systematically interpret TDR signals by understanding the electromagnetic wave phenomena and TDR system characteristics. The performance is evaluated by analyzing the data obtained from a laboratory experiment. Results indicate that the algorithm accurately determines the thickness of sedimentation. In addition, the TDR scour monitoring system provides real time estimation of sediment physical condition including the water content and density. The system will be a valuable tool for investigating bridge scour mechanism and will have important engineering application potentials.

The use of bender elements to generate and receive shear waves in soils has become a very popular technique in geotechnical engineering studies. However as with any other wave propagation technique, the interpretation of bender element-collected data is controlled by wave characteristics, boundary conditions, and properties of the medium. This paper presents experimental data and simple closed-form solutions in order to investigate and to evaluate the effects due to the near field and boundary conditions in different types of specimen geometries and boundary conditions. Results yield dimensionless limits that must be taken into account to properly monitor soil parameters and to avoid misleading results in the interpretation of wave propagation data from the bender elements.

In this paper, uncemented and cemented sand behavior under the K₀-condition is investigated using both mechanical and electromagnetic waves. Stress-induced cross-anisotropy can be characterized in uncemented sand by measuring S-wave velocities propagating in different polarization planes; in cemented sand, the cementation hinders the stress dependence of the S-wave velocity and so does the response of cross-anisotropy. The aging effect favors the proliferation of horizontal force-chains so that a greater velocity increment of the wave propagating and polarizing in the horizontal direction is measured. This effect is weakened by cementation. In response to vertical loading, sand particles are prone to align in the horizontal direction. Thus, values of the conductivity ratio, alpha (i.e., the conductivity in the vertical direction over the one in the horizontal direction) decrease with increasing vertical loading.

Electrical resistivity tomography (ERT) is a non-invasive imaging technique capable of evaluating the distribution of electrical properties within cross-sections of soil specimens. The technique provides an alternative for the monitoring of processes in soils that may not yield mechanical or density contrasts. In this paper, a series of experimental test results is presented, where the diffusion of chemical fronts, in a cylindrical soil specimen, is monitored by measuring boundary electrical currents and voltages. The data are then inverted for the generation of electrical resistivity tomographic images. The experimental study includes the testing of a coarse cylindrical soil specimen that is diffused and seeped with a NaCl solution. The electrical properties are monitored with sixteen electrodes arranged in a plane perpendicular to the longitudinal axis of the specimen. Such an arrangement allows the imaging of the chemical diffusion process in the soil specimen. The results provide robust data sets that allow for the evaluation of diffusion parameters in soils. These parameters can later be used in the calibration and validation of numerical models.

Stiffness is the main engineering parameter generally used in the structural design of highways. However, adequate in-place density is normally used for acceptance criteria. Several nondestructive Testing (NDT) methods have been recently developed to supplant the conventional methods. Seismic methods are one example. In this paper, a procedure to measure the modulus of each pavement layer after placement with seismic technology is presented. Field and laboratory tests are incorporated so their results can be reconciled without any scaling or simplifying assumptions. The overall procedure and a case study are described here.

The discrepancy among results of various surface-wave tests is reported. In Korea, universities and industries collaborated to compare the reliability of surface waves including the Spectral-Analysis-of-Surface-Waves (SASW) method, the Multichannel Analysis of Surface Waves (MASW) method, the Harmonic Wavelet Analysis of Waves method (HWAW) and the Refraction Microtremor (ReMi) method at a given geological site. The resulting shear-wave velocity profiles were compared with borehole seismic test results. Also, the stratification evaluated by surface-wave tests is compared with the stratification by borehole logs and SPT-N values. The distinct difference between the SASW and the MASW methods was identified in the depth resolution of the 1-D shear wave velocity and in the accuracy of the 2-D spatial profiling of subsurface stiffness. The effects of seismic source, the sensitivity of sensors and the forward modeling theory are discussed to explain the discrepancy between the SASW method and the MASW method.

Site effect has been known as the major cause of large ground amplifications during several recent catastrophic earthquakes. Consequently, the evaluation of site effect is an important factor that must be considered in mitigation of earthquake hazards. Shear wave velocity is a key parameter that controls dynamic response of a site. Hence its profile must be identified down to the seismic bedrock. Generally geotechnical or even geophysical methods are expensive and time consuming for this purpose. As an economical and practical substitute, microtremor measurements can be used. In order to investigate the reliability of shear wave velocity (V_s) profiling by using microtremors, a series of microtremor measurements have been conducted in Bam city (southeast of Iran) which experienced the damaging earthquake of December 2003. Microtremor measurements included both one-point and array observations. However, only the array measurement data are considered in this study. Based on the dispersion characteristics of Rayleigh waves, V_s profiles were determined at array measurement sites using inverse analysis. Ultimately, reliability of the inverted soil profiles was investigated, comparing results of microtremor measurements and seismic refraction and down-hole methods.

To obtain a shear-wave velocity (V_S) profile in geotechnical practice, various seismic investigations are being frequently used. Due to discordant shear wave velocity profile of each test, it is important to develop the representative V_S profile considering the reliability and applicability of each seismic test. In this study, a model testing site which composed of four local layers with size about 16m*26m*8.5m (W*L*H) was designed and constructed for a comparative study of field seismic tests. To evaluate the dynamic material properties of each layer, total of 140 vertical and horizontal geophones were embedded at the boundary of each layer, and the locations of geophones and model geometry were measured by surveying during construction process. Using the interval travel time between embedded geophones, the body wave velocities of each layers were obtained as reference data for evaluation of other seismic tests. Down-hole, SASW, MASW and HWAW tests were performed at the model testing site and the V_S profiles of each test and reference data of model site were compared. The advantages and disadvantages of applied seismic tests and the reliability of new innovative HWAW method were discussed.

Three commercially-available seismic surface wave methods (SWM) were tested at a challenging site containing a high velocity layer (HVL). Methods tested included two active-source SWMs, the Spectral Analysis of Surface Waves method and the Multichannel Analysis of Surface Waves method; and one passive-source SWM, the Refraction Microtremor method. A borehole log and data from a shallow downhole seismic measurement were also available for comparison. While shear wave velocity profiles for the three methods were different, slowness-averaged velocities were comparable. None of the SWMs successfully resolved the HVL. The underlying cause can be the inherent capacity of the methods for averaging velocity with depth.

The cone penetration test (CPT) is widely used for geotechnical and geo-environmental site investigations. The objective of this paper is to discuss the current developments of CPT in China and the Western countries. Detailed discussion is made on the current development and achievements of the modern multifunctional digital CPT technique. The difference between the Chinese CPT and the international modern multifunctional digital CPT techniques are compared. A brief review of geoenvironmental site investigation using modern CPT technology is presented. Finally, some feasible advices about the development of Chinese CPT techniques are provided in order to change the lagged status of CPT technology in China.

In this paper, application of the CPT cone resistance (q_c) for footing bearing capacity estimation is examined. The analysis focuses on axially loaded circular footings bearing on sand. The approach proposed in this study can reduce the uncertainties associated with the bearing capacity equation, as no estimation of φ or selection of an equation for N_γ is necessary. Instead, normalized limit unit bearing capacities q_bL/q_c are calculated from non-linear finite element and cone penetration resistance analyses for various soil and footing conditions. Based on results in this study, a method for estimating q_bL directly from the CPT cone resistance (q_c) is proposed. Effects of the relative density (D_R), the lateral earth pressure ratio (K₀) and the footing size are also addressed. There is a size effect on the values of q_bL/q_c. The size effect increases as the footing diameter B increases.

Current analyses of seismic cone penetration (SCPT) test data assume that seismic rays travel in a straight path between the source and receivers. While this holds true for single-layered homogeneous soil, soil layers cause rays to reflect and refract, resulting in a deviation from their normally assumed straight-path geometry. This paper presents results of simulated SCPT tests designed to study the effects of soil layers on travel path length. These results show that, in general, variations between true and assumed direct travel paths are small and can be ignored in SCPT calculations.

Shear wave velocity (V_s) and cone penetration data are collected from sites worldwide. The data represent different soil types including sands, clays, intermediate soils, and mine tailings. The statistical correlations between V_s and different cone parameters were examined. The soil behavior type index (I_c) represents most of the variability of the V_s data. Regression models are fitted and a global statistical correlation between normalized V_s and I_c is developed for different soils. The derived correlation is verified at a selected site where the soil stratigraphy is relatively complex.

The overconsolidation ratio (OCR) and coefficient of earth pressure at rest (K_o) of clays are important factors influencing the strength, stress-strain behavior, and the compressibility characteristics of cohesive soils. This paper evaluates the feasibility of using an artificial neural network (ANN) model for estimating the OCR and K_o of soil deposits from piezocone penetration test (PCPT) data. An ANN model was developed using the general regression neural network (GRNN) algorithm, and trained using actual PCPT records from test sites around the world, together with the corresponding oedometer OCR test results and empirically determined values of K_o. After training, the GRNN model was tested using previously unseen PCPT data, and model predictions were compared to reference oedometer OCR values and empirically determined K_o values to evaluate the network's success. Model predictions were also compared with some of the existing interpretation methods.

Since soil modulus is highly nonlinear from the small-strain to intermediate- and large-strain regions, the initial tangent shear modulus (G_max) provides a fundamental reference value for maximum stiffness. The seismic piezocone test (SCPTU) is appropriate for obtaining soil parameters both at the small and high strain ranges. A nonlinear modulus reduction subroutine is embedded in the two-dimensional finite difference program FLAC to simulate soil stress-strain nonlinearity. The model is based on a logarithmic function that requires only three parameters to describe the nonlinear soil response: shear strength (τ_max), initial shear modulus (G_max), and strain at failure (γ_f). A numerical parametric study was performed and a closed-form solution for representing the load-displacement response of footings was developed that was calibrated with full-scale footing load tests.

DMT (Marcheti Flat Dilatometer Test) has been increasingly used with success in the evaluation of geomechanical properties of soft to medium soils, with moderate compacity or consistency (N_SPT less than 30). The insertion of the Flat Blade has been traditionally made by static pushing, which is an operational limitation in hard to stiff soils, in particular in heterogeneous saprolitic residual soils. This has been limiting the practitioners, when, as in Portugal, pressuremeter test is not common practice, leading to rely exclusively in dynamic penetration test (such as SPT or DPSH — super-heavy dynamic probing), which are very limited in, among other levels, deriving stiffness properties. In this context, the dynamic penetration of the DMT blade has been explored as an alternative to static push-in, assuming that the characteristics of the test — by inducing a solicitation that is eminently horizontal, may, in some way, preserve the intrinsic characteristics of the natural soil. This is being explored as a possible potential of this device for these natural ambient. The present paper will be presenting a comparative analysis of the results obtained in both static and dynamically push-in DMT tests in weathered profiles of granitic masses and reference earthfills.

The flat dilatometer test has been increasingly used in the geotechnical engineering investigations and applications. To learn about the test mechanism, a simulation of dilatometer penetration and test process in a "virtual" soil model using the finite element analysis are discussed. By modeling the process of membrane's expanding, a more realistic test process is modeled in which the dilatometer is assumed to be rigid and the soil is assumed to be an elastoplastic continuum obeying the non linear harden criterion. Parametric studies are performed to illustrate the influence of various factors on the test results at the limit state. At last, a correlation between horizontal coefficient of sub-grade and test pressure is given.

This paper presents an analysis of the bi-dimensional-membership-function-based site fuzzy classification method is presented. A site fuzzy classification method based on Back Propagation (BP) network is proposed. The training of fuzzy networks of four types of standard sites is fulfilled. The BP-based method overcomes the bi-dimensional membership function's defect of being not gradual or gentle but involving irregular or abrupt breaks at the surfaces (junctures of planes). Therefore, this method makes the classification result better meet requirements of practical construction. Based on the fuzzy classification networks of four standard sites, a BP-based site classification method is proposed. Space distribution graphics of this method is provided. Thus, intelligence, accuracy and continuity of site classification are realized. Finally, an intelligent continuity method of site characteristics period is established and space distribution graphics of characteristic period are presented as well. We can hereby ascertain both a continuous seismic reflection curve and the seismic action more objectively and reasonably.

An on-going research at the University of Texas at Arlington has attempted to develop correlations between Dynamic Cone Penetrometer (DCP) test measurements and strength results of cement and lime stabilized expansive soils. The DCP is used in this research since it is a simple, portable, fast and inexpensive method and can provide rapid assessments of strength enhancements with chemical treatments. The DCP device has a conical tip, which is connected to a series of slender rods along with a 15 pound sliding hammer. DCP tests were conducted on control (untreated), cement- and lime- treated soil specimens at four different time periods, 0, 3, 7 and 14 days after stabilization. The number of blows per selected depth of penetration was measured along the depth of treated soil specimen. The measured DCP data was correlated with laboratory strength measurements. Effects of stabilizer, dosages, and curing period on the DCP measurements were addressed. Both cement and lime treatments provided strong DCP correlations with high coefficients of determinations.

The Borehole Shear Test (BST) and the Rock Borehole Shear Test (RBST) are unique among various in-situ testing methods for field investigations in that they provide direct measurements of soil and rock shear strength parameters. This paper reports a case history of BST and RBST measurements for the shales from a recent highway embankment slope project. The results show the shear strengths measured are highly variable. The large amount of shear strength data provided the opportunity to conduct slope stability analyses from a probabilistic perspective, which may ultimately save millions of dollars in proposed ground improvement measures.

An in situ test was conducted to investigate the short-term mechanical behavior of soft clay in Guangzhou, China, by using the Menard pressuremeter. The methodology for identifying soft clay parameters by using the plane strain elasticity theory and the radial expansion equation of cylindrical hole in infinite elastic medium provided by Lame to interpret the test data is introduced in this paper. The initial horizontal pressure, the critical plastic pressure and the limit load are obtained from the pressuremeter testing curves, and then, the pressuremeter modulus and the shear modulus are calculated. The procedure, applied here to identify the soft clay parameters from a pressuremeter curve, is based on an inverse analysis approach.

The Menard pressuremeter test can be successfully performed at any depth, this pressuremeter (designated by PMT) has a greatest advantage for seabed and other underwater tests from floating platforms, since there is no need for a stiff linkage between the probe and the drilling platform. In-situ test of a bridge foundation ground, envolving underwater sedimentar soft clay and sand by using GA pressuremeter, is introduced. Based on the interpretation of drill borehole geologic data, a linear relationship between standard penetration test values (N_63.5) and bearing capacity of foundation based on pressuremeter test was assumed. The correlation between N_63.5 and bearing capacity of foundation derived from PMT are different because of the difference of soil properties. For hard soil foundation, the increasing degree of bearing capacity of foundation calculated from pressuremeter test with N_63.5 is small. And the increasing degree of bearing capacity of foundation calculated from pressuremeter test with N_63.5 is rather large for soft soil foundation. It can be well used for ascertaining the ground bearing capacity by SPT and partial pressuremeter test data and determining the position of supporting course.