Long-term Deformations of a Historical Church on the Anzer Island, White Sea
Chernyshev Sergei N.
ABSTRACT: Current study is aimed at determining the rate of the sand ground dislocations near the ultimately steep slope. The purpose of this work to determine the velocity of the sandy soils on flat ground on extremely steep to slope. In order to determine the rate, we conducted periodical measurements of the width of the tensile fractures in the load-bearing walls of the building constructed in 1830. Building of the object and its restoration in the current century have led to the imperfect structure of the building, lacking steel ties in the brick walls, which should have been installed at different levels, specifically under the floor and at the level of the vault abutment. The absence of ties has resulted in rupturing of examined building due to tensioning of the moving foundation. The errors of the constructors have transformed this building into an experimental object. The direction and the velocity of the ground movement have been determined. Our results suggest that tensioning of the foundation should be considered when designing the structure of the buildings constructed on the sandy layer near bents.
KEYWORDS: Sandy Layer, Engineering geology, Slope, Brick building, Fractures, Tension
Seismic Observations on Piled Raft Foundation Subjected to Unsymmetrical Earth Pressure During Far Earthquake and Near Earthquake
J. Hamada and K. Yamashita
ABSTRACT: Seismic observations on piled raft foundation subjected to unsymmetrical earth pressure have been conducted just after the 2011 off the Pacific coast of Tohoku Earthquake. The seismically monitored building is a seven-story building with three basement floors, subjected to unsymmetrical earth pressure, located in Tokyo, Japan. Accelerations of the building, dynamic sectional forces of the piles and dynamic earth pressures on both sides of the embedded foundation and those beneath the raft were observed during over 550 seismic events including an earthquake with a magnitude of M8.1. The maximum acceleration of 0.358 m/s2 was observed on the building foundation. Based on the seismic records, it was confirmed that a lateral inertial force of the building was transferred to the subsoil through the raft. Comparing to different seismic type, the bending moments on piles due to far earthquake having relatively long period were larger than those due to near earthquake. It was also found that the ratio of the lateral load carried by the piles to the lateral inertia force of the building was estimated to be about 10 to 30 %.
KEYWORDS: Piled raft foundation, Seismic observation, Unsymmetrical earth pressure
Determination of Virgin Compression Destructuring Line Parameters for Natural Clays
M. Manzur Rahman and Mohammed K. Islam
ABSTRACT: Based on the destructuring framework proposed by Liu et al. (2015) preceded by the work by Liu and Carter (1999, 2000), the virgin compression destructuring behavior of fifteen natural soil published in various literature over the last seven decades in several locations around the globe have been studied. Two methods (i.e., graphical and two reference point approach) to determine the parameters used in the equation of compression destructuring line (CDL) are proposed and examined by simulating the experimental data. Also, a systematic approach to find the yield pressure is suggested. The study concluded that CDL parameters obtained from graphical approach successfully predicted the compression behaviors of structured soil for most of the soil samples. Nonconformity occurs in case of two reference point approach in some cases. The two reference point approach is very helpful for a quick approximation of the CDL parameters because of its simplicity. Theoretically, two reference point method should be independent of the selection of the two point sets and always yield the same parameters but due to the uncertainty of the precision of experimental data, it varied. The author used and suggested a universal by taking furthest two points on the destructuring compression data as references. Also, the analytical approach to locate the yield pressure point is found very helpful. These methods eliminate the rigorous process of trial and error to find CDL parameters and other conventional processes to locate the yield pressure.
KEYWORDS: Structured soil, Soil destructuring, Compression destructuring line, Yield pressure, Compression destructuring index
Effect of Liquid Polymer on Properties of Fine-Grained Soils
H. Soltani-Jigheh and S.N. Tahaei Yaghoubi
ABSTRACT: One of the most useful methods for improving engineering characteristics of soils is soil stabilization by chemical additives like cement, lime and polymer materials. Since polymeric additives are easier to handle, they have been used widely in geotechnical projects in recent years. The current practice is to evaluate the effect of CBR-Plus polymer on the physical and mechanical properties of fine-grained soils. For this purpose, CBR-Plus polymer was mixed with two high plasticity fine-grained soils and Atterberg limits, compaction and consolidated undrained (CU) triaxial tests were carried out on the compacted mixture in the laboratory. Interpretation of the results using scanning electron microscopy (SEM) images were carried out. Results show that CBR-Plus has insignificant effect on plasticity index and compaction characteristics of soils. Some amount of CBR-Plus additives lead to increase in shear strength of specimens. In fact, depending on the type of the soil, there is an optimum amount for this polymeric material in which the shear strength increases.
KEYWORDS: Fine-grained soils, CBR-Plus polymer, Triaxial test, Shear strength, SEM images
Geotechnical Aspects of Infrastructure Projects in Gypseous Soils
Safa Hussein Abd-Awn and Heba Qasim Hussein
ABSTRACT: This paper presents the behavior of single tension pile in collapsible soil (Gypseous soil) by experimental work. The natural Gypseous soil with 66% gypsum used in the study was brought from Salah Al-Deen governorate in Iraq while that of the sand was brought from Karbalaa governorate, south of Baghdad, Iraq. The model pile used is smooth steel pipe pile with slenderness ratios (L/D) of 10, 15, 20 and 25. The effect of the gypsum content included in the soil as well as the effect of rest time and the effect of (L/D) on the pullout capacity of pile were studied in the laboratory scale model pile. The results showed that the pullout capacity of pile in Gypseous soil is more than its capacity in Sandy soil by about 64%. When the rest time was increased, the pullout capacity of tension pile embedded in Gypseous soil decreased. Increasing (L/D) ratio of pile in Gypseous soil from 15 to 20 increases pullout capacity of pile to about 65%, while increasing that ratio from 20 to 25 increases pullout capacity of pile to about 76% .
KEYWORDS: Model piles, Pullout capacity, Time effect, Slenderness ratio, Gypseous soil, Sand
Influence of Nano Copper Slag in Strength Behaviour of Lime Stabilized Soil
M. Kirithika and V.K.Stalin
ABSTRACT: Nanotechnology has been widely used in many applications such as medical, electronics, and robotics also in geotechnical engineering area through stabilization of bore holes, grouting etc. In this paper, an attempt is made for understand the influence of nano copper slag (1%, 2% & 3%) on the index, compaction and Unconfined Compressive Strength (UCS) properties of natural soil (CH type) with and without lime stabilization for immediate and 7 days curing period. Results indicated that upto 1% of nano copper slag, there is an increment in UC strength of virgin soil and lime stabilised soil. Beyond 1% nano copper slag, there is a steep reduction in UC strength and increase of plasticity both in lime stabilised soil and virgin soil. The effect of lime is found to show more influence on large surface area of nano copper slag in natural soil. In lime stabilised soil, for both immediate and curing effect, with 1% of nano copper slag the maximum unconfined compressive strength was 38% and 106% higher than that of the virgin soil strength.
KEYWORDS: Lime, Nano copper slag, SEM, Unconfined Compression Strength, XRD
Slope Stability Problem and Bio-engineering Approach on Slope Protection: Case Study of Cox’s Bazar Area, Bangladesh
Md Shofiqul Islam and Atikur Rahman
ABSTRACT: The slope stability problem of the six (06) locations in the Cox’s Bazar district, Bangladesh were analyzed through laboratory measurement of the engineering properties of the soil samples, tensile strength of roots and numerical modeling using both limit equilibrium and finite element method. The modeling results show that the slopes are stable (FS value greater than 1) at the dry condition and the wet condition unless rocks are weathered. At the wet condition most of the slopes with loos soil are vulnerable for landslide and need supports to stabilize. We suggested the vegetal support (tap-rooted tree) to stabilize the vulnerable slopes of the study area. The experimental result shows that the roots of the local growing tap rooted trees (e.g., Chapalish, Korai, Gorjon, Telsur) grew linearly within a few years. The roots reached their length of 3-5 m within 4/5 years, yielding tensile strength of 70-80 MPa that enough to avoid the slope failure.
KEYWORDS: Slope stability, Slope angle, Cohesion, Factor of safety, Root tensile strength, Cox’s Bazar
Geotechnical Characterization and Behaviour of Tunis Soft Clay
Nadia Mezni and Mounir Bouassida
ABSTRACT: Tunis soft clay being known as one of the most problematic soils has poor mechanical characteristics, high compressibility and exhibits fragile shear strength. This paper considers the geotechnical characterization of Tunis soft clay by compiling results from in situ and laboratory tests. Accordingly, some correlations are suggested. The assessment of observed behaviour of Tunis soft clays in the zone of interchange ramps was investigated. The follow up of ramps behaviour was performed for a period of three months. The evolution of settlement was monitored by rod settlement, hydraulic settlement and multi-points settlement. A plane strain model was built for numerical investigation conducted by Plaxis software to simulate the behaviour of the ramp’s embankment. Hardening Soft Soil Model (HSM) and Soft Soil Model (SSM) were adopted for the soft clay layer. The results showed an agreement between the predictions of the two models of the behaviour of the soft clay. Using measured settlement, the adopted behaviour for Tunis soft clay is justified.
KEYWORDS: Geotechnical investigation, Data, Characterization, Simulation, Soft clay, Behaviour
Strength of Peat Treated with Peat Ash
Mingyang Zhou and Kwong Soon Wong
ABSTRACT: For construction on peaty ground, shallow peat layer is normally replaced by stiffer soil. The replaced peat may be burned into peat ash to reduce the volume. In this study, the potential of peat ash in improving the shear strength of peat was investigated using unconfined compression tests. It is found that peat ash has insignificant effect to the 7 days strength of peat. Peat ash increases the strength of peat by about 50% at Day 14. At Day 28 and 56, the effect of peat ash to strength of peat is comparable to the effect of cement, whereas the effect of cement is about 10% larger than that of peat ash. It is found that effect of peat ash in strengthening the peat become less significant with the present of cement.
KEYWORDS: Peat, Peat ash, Cement, Unconfined compressive strength
Temperature-Stress Analysis of Rock-Shotcrete Structure under High Temperature Cooling Effect
Hui Su, Min Liang, Baowen Hu, ZhouXiang Xuan, Yue Xin, and Yi Zhu
ABSTRACT: Take the diversion tunnel located in geothermal area as engineering background, the coupled temperature-stress analysis of rock-shotcrete structure with high temperature was performed under immersion action of cold water. The Physical and simulation experiment show that temperature evolution of rock-shotcrete structure can be classified into three stages, which are initial rapid decay stage, deceleration decay stage and the equilibrium stage; The stress simulation shows that the sharp change of stress will occur in the shotcrete layer during the first stage, and maximum principal stress is mainly manifested as tensile stress, which will easily lead to tensile failure of the shotcrete layer; the displacement simulation shows that the rock-shotcrete structure takes on overall shrinkage deformation in each temperature stage, and it is most obvious for shotcrete layer. The deformation of rock plate will not stop until temperature reaches stable state. Such kind of deformation law will weaken constraint on the shotcrete material, and therefore lead to stress relief in the shotcrete layer.
KEYWORDS: Temperature-stress coupling, Numerical simulation, Diversion tunnel, Rock-shotcrete structure, Attenuation stage
Applicability of Hyperbolic Method for the Prediction of Shear Strength Parameters from Multistage Direct Shear Tests
A.Sridharan, Santhosh Kumar. T.G, Benny Mathews Abraham and Sobha Cyrus
ABSTRACT: Measurement of shear strength through a conventional direct box shear test involves the requirement of at least three identical soil specimens. The collection of samples and carrying out a number of tests is very expensive and time consuming. Multistage shear strength test provides a faster method for the determination of shear strength parameters of a soil through tests on a single sample. Earlier studies conclusively proved the effective use of multistage triaxial compression test to predict the shear strength of soils. In this paper an attempt is made to study the possibility of using multistage box shear tests on a single soil sample instead of the conventional box shear tests to predict the shear strength. Undrained direct shear tests conducted on three different soil types – medium sand, air dried Cochin marine clay and red earth showed very good agreement between the results of multistage and conventional box shear tests. It has been brought out that the stress-strain curve in the shear box test follows the hyperbolic form throughout the test. Hence, it is possible to predict the failure shear stress, knowing the stress-strain relationship for the initial portion only. Making use of this behavior, multistage tests were carried out on single sample changing the normal load after obtaining initial portion of stress- strain behaviour. It has been brought out that the conventional box shear test could be approximated to multistage box shear test using only one soil sample, avoiding the variability between three or four soil samples used in a conventional test. The test procedure has the distinct advantage of requiring only one sample coupled with large saving in time without much compromise on the accuracy.
KEYWORDS: Box shear test, Multistage test, Shear strength, Medium sand, Marine clay, Red earth
Behavior of Foundation on End-bearing Stone Columns Group Reinforced Soil
Seifeddine Tabchouche, Mounir Bouassida and Mekki Mellas
ABSTRACT: The prediction of the settlement of foundations on soil reinforced by a group of end-bearing stone columns was investigated. 3D numerical models with constant improvement area ratio are considered into two configurations. The first configuration consists of stone columns group located in regular triangular pattern. Whilst, an equivalent reinforcement by concentric crowns is used by the second configuration. Geotechnical parameters of the reinforced soil modeled by the Mohr Coulomb constitutive law are adopted from Tunisian case history. Numerical predictions of the settlement by the finite difference code FLAC 3D and analytical ones by Columns and COLANY software are compared. It has been verified that the settlement prediction by the unit cell model is underestimated in regard to predictions obtained by the 3D reinforced soil models. Elsewhere settlement predictions by the equivalent concentric crowns are close to those obtained by the corresponding models of stone columns group reinforcement. When the equivalent concentric crowns reinforcement is adopted the increase in contact area with the soft soil does not affect the settlement prediction when total adhesion is assumed along those interfaces. Using the FLAC 3D code, it is more suitable to handle the input data by the equivalent concentric crowns to perform the computations.
KEYWORDS: Soft soils, Stone columns, Settlement prediction, Finite difference, Improvement area ratio
Instrumented Piles Tested in 1969 in Fine Loose Sand at Holmen, Drammen: Revisited 2019
A.S. Balasubramaniam, J.M.N.S. Jayasiri, E. Oh, G. Chao, H. Kim, R. N. Hwang
ABSTRACT: The work presented here relates to the instrumented piles tested in 1969, by the Norwegian Geotechnical Institute (NGI) in loose sand at Holmen, Drammen. The material contained in the first publication, which is an Internal Report F.273.0 of NGI (Balasubramaniam et al., 1969), was mainly on the load tests only and contained the analyses of the vibrating wire gauges as based on the zero of the gauges after the pile driving, to make sure the best set of zero values were used. The publication of Gregersen et al. in 1969, includes pull out tests and also the effect of the residual stresses developed in the piles during pile driving. Further, the work of Gregersen et al. contains a detail section on the performance of the vibrating wire gauges and in particular the drifting of the zero of the gauges. The entire pile testing work and reporting in NGI internal report F.273.0 (Balasubramaniam et al., 1969) included a description of the instrumentation used and the results obtained from load and pull out tests on precast reinforced concrete piles. The piles, of circular cross section and available in standard lengths, can be joined together in the field by means of threaded connectors. The primary purpose of the instrumentation was to determine the distribution of axial load along the length of the pile and the point load and also to measure the distribution of lateral earth pressure acting on the periphery of the pile. To accomplish these goals, the piles were equipped at a number of levels with strain gauges embedded in the concrete, on the reinforcing steel, and earth pressure cells on the sides of the piles, together with hydraulic piezometers for measuring pore water pressure in the sand. The instrumentation system was based on the operating principle of the vibrating-wire strain gauge (Bjerrum et al., 1965). Altogether four instrumented piles were used in the test program, three cylindrical and the fourth conical in shape, and had a uniform taper, typical for a Norwegian timber pile. The piles were constructed in such a manner that the 8m long cylindrical and conical piles can be tested first and later, after completion of these tests each one of them can be lengthened by connecting additional 8m segment of instrumented cylindrical pile to make up two 16 m long test piles. The test program also included additional tests on a single pile, which was made up of 4 m long precast concrete pile sections driven one section at a time and tested for embedded lengths of 3.5, 7.5, 11.5, 15.5, 19.5 and 23.5 m; the latter pile only had load cell at the top to measure the applied load and was not instrumented.
KEYWORDS: Pile load test, Bearing capacity, Pull out test
Application of Electrical Resistivity Imaging and Slope Modelling in the Investigation of Landslide Sliding Geometry in Phuket
ABSTRACT: Over the last decade, landslides triggered by rainfall in Phuket have been a major problem affecting development and tourism. An investigation of areas susceptible to landslides is necessary in order to institute policies to reduce the impact of landslide and to ensure the safety of tourists. In this study, two-dimensional electrical resistivity imaging (2D-ERI) was applied and slope stability modelling was conducted to investigate the sliding surface and the thickness of the sliding mass in a study area which is prone to landslide during intense and prolonged rainfall. The result of the 2D-ERI was used to validate the result of a simulation of the slope stability to determine the landslide sliding surface and the thickness of the sliding mass based on rising piezometric head due to rainfall. Further, the model geometry of the slope stability was reconstructed using the 2D-ERI data, and the simulation was repeated. The result for the factor of safety (FS) when the piezometric head was rising was found to have been overestimated in the original simulation Therefore, the reconstruction of the model geometry is essential to avoid the over-estimation of the FS in slope stability modelling in conditions of rising piezometric head.
KEYWORDS: Landslide, Sliding surface, Electrical resistivity imaging (ERI), Slope modelling, Factor of safety (FS)
Comparison of Flexural stiffness between Hat-type and U-type steel sheet pile retaining walls in a Field Test in Singapore
S. Moriyasu, S.P. Chiew, K. Otsushi, N. Matsui, S. Taenaka, K. Teshima, M. Tatsuta and H. Tanaka
Abstract: The use of the Hat-type steel sheet pile can potentially improve the performance of earth retaining walls because of two of its features: its wide width and location of interlocks. It can reduce the piling time and number of piles required for walls because of its 900-mm width, which is the widest among the hot-rolled monopiles in the world. Furthermore, Hat-type piles can achieve full-shear force transmission at the interlocks because their connections are located at the outer edge of the wall. This study focuses on the second feature, i.e., the interlock shear force transmission. The lateral load and excavation tests were performed to compare and verify the difference in the interlock behavior between U-type and Hat-type sheet piles. As the result, in contract to the reduction of shear force transmission of the U-pile wall, the Hat-pile wall exhibited high flexural stiffness because the interlocks achieved the full-shear transmission mode.
