Strength Characteristics of Soda Waste Treated with Fly Ash and Lime
By Hai-lei Kou and Wen-gang Zhang
ABSTRACT: Soda waste is a kind of industrial waste when traditional technology of soda production is adopted. The soda waste cannot be directly used as engineering soil as its low strength. However, it can be used after be mixed with other materials. In this paper, chemical materials such as fly ash and lime are used to be mixed with soda waste. The strength characteristics of soda mixtures with different ratio are studied in detail. Compaction test and unconfined compressive test are conducted respectively to assess the feasibility of these two materials. Based on test results, the mechanical properties of soda mixtures with different ratios of fly ash and lime are discussed. It is indicated that the microstructure of soda waste is similar with soil and the particle size distribution is well to mix with other materials to be used as engineering soil. The optimal ratio of soda waste and fly ash is 7:3 while the ratio is 7 % for soda waste and lime. Using the optimal ratio, the unconfined compression strength of fly ash treated soda and lime treated soda after 14 curing days is 6.5 and 6.1 times of pure soda respectively.
KEYWORDS: Soda waste, Fly ash, Lime, Compaction test, Unconfined compression test
Groundwater Recharge Estimation in Kathu, Phuket using Groundwater Modelling
By A. Puttiwongrak, K. Sam O and V. Sakanann
ABSTRACT: Kathu is a district of Phuket Island in Thailand, and is the district with the largest number of communities in Phuket. Groundwater is the main water supply on Phuket. Urbanization is occurring very rapidly on Phuket and this has stimulated water demand at an accelerating rate. A lack of fresh water and the results of over-use of groundwater could be serious problems in Phuket in the near future. The study described in this paper simulated groundwater recharge flux in Kathu, using groundwater modelling to estimate groundwater recharge. The simulation was carried out across the locations in Kathu for the period, 2006-2016. Historical Groundwater well data were collected and used to create a groundwater model. The trial and error method was applied to the recharge flux to obtain matches between simulated and observed figures of groundwater heads or levels within acceptable ranges of error. Finally, it was concluded that the groundwater recharge in Kathu is currently able to maintain the groundwater level, although groundwater has been withdrawn at a highly accelerating rate, especially between 2012 and 2016. The positive trend in the recharge rate can be attributed to increasing efficiency in the use of water catchment areas, high rainfall, and rising sea levels.
KEYWORDS: Phuket groundwater, Recharge flux, Groundwater level changing, Groundwater modelling, Urbanization.
Seismic Microzonation of Cox’s Bazar Municipal Area Bangladesh
By A. Imtiaz, A. Barua, M. Sakib and M.A. Ansary
ABSTRACT: Cox’s Bazar municipal area runs a high risk of earthquake exposure due to geologic and tectonic structures. As a part of adopting earthquake mitigation approaches for the region, a seismic microzonation map was developed on the basis of potential of earthquake occurrences and ground susceptibility to earthquake. For microzonation purposes, a total of 26 borelogs were used to study site amplification as well as soil liquefaction potential of the municipality area. Site responses were estimated through one dimensional wave propagation software SHAKE. The liquefaction potential was evaluated using two simplified procedures, proposed by Seed et al. (1983) and Iwasaki et al. (1986) to measure whether the site is liquefiable or non-liquefiable. For slope stability analysis, XSTABL programme was used which performs two dimensional limit equilibrium analyses to evaluate the factor of safety for a layered slope using the simplified Bishop Method. These results were transformed into a map which will serve as a general guide to ground-failure susceptibility, effective land use, and efficient town-planning.
KEYWORDS: Seismicity, Ground Liquefaction, Site Amplification, Slope Stability, Microzonation
Geophysical Investigation in Bukit Merah Reservoir
By M. R. Selamat, A. Shafie, R. Saad, and M. M. Nordiana
ABSTRACT: The suspected cavity presence in the bedrock of the outlet canal of Bukit Merah Reservoir in Malaysia raised concern that it could undermine the integrity of a check pier structure planned just ahead of the spillway. Boring into a cavity could also compromise reservoir containment capacity. A seismic refraction and electrical resistivity tomography carried out for the subsurface section spanning the two banks revealed not only the presence of a relatively porous zone towards one end but also the undulating material boundaries towards the other. The results called for review of the original foundation of the check pier structure involving bored piles of equal length. The suspected porous zone was avoided in the renewed bored pile design while the bedrock depressions were appointed with deeper bores for adequate pile embedment. The design review resulted in piles resting on a stratum of equal geotechnical quality with each new pile now having a different length.
Keywords: Bored pile foundation, Suspected cavity, Seismic refraction, Electrical resistivity, Relative porous zone, Design review
Effect of Ground Disruption on the Strength of Gatch Soil in Kuwait
By Ziad Abdelsalam and Nabil Ismael
ABSTRACT: Kuwait soil is commonly known as ‘Gatch’ and classified as very dense cemented sand Kuwait sand has sulphates and calcium carbonated in form of gypsum components that caused cementation bonds with environment aids such as highly evaporation of rainfall in winter season. This soil is used as a backfill material and it is important to know the effect of excavation and recompaction on the strength characteristics. The present study provides experimental results on the effect of ground disruption on strength parameters of cemented sand in Kuwait, such as the are the cohesion c, and the angle of friction ϕ’ and stress strain characteristics. The triaxial test was used to determine these parameters on undisturbed and remolded specimens at different depths. The results show a disturbance of cemented sands cause loss of the cohesion component of strength and a minor reduction in the angle of shearing resistance.
KEYWORDS: Cemented Sands, Kuwait Soil, Drained Triaxial Test, Compaction Test.
Greenheart Timber Strip Reinforcement for Reinforced Soil Retaining Walls
By Sean A. Surujdas and C.N.V. Satyanarayana Reddy
ABSTRACT: This article presents the result of investigating the feasibility of using greenheart timber strips as reinforcement for reinforced soil retaining walls in Guyana. The work is intended to assess the cost economics between greenheart timber strips and geogrids as reinforcements. Medium grained river sand is used as fill material in reinforced soil retaining wall designs. The interfacial friction between greenheart timber and fill material is determined by the laboratory pullout test. The designs of reinforced soil retaining wall revealed that Greenheart timber strips of 350mm width and 25mm thickness are sufficient to reinforce retaining walls with backfill of heights 4m and 6m, while greenheart timber strips of 350mm width and 50mm thickness are sufficient to reinforce retaining walls with backfill of heights 8m and 10m. It is observed that as height of retaining wall increases from 2m to 10m, the percentage cost saving of using greenheart timber strips as compared with geogrids, increases from 10% to 24%.
KEYWORDS: Greenheart timber, Pullout test, Interfacial Friction, Cost Economics, Reinforced Soil, Geogrid, Retaining wall.
HWYL Method for Predicting Settlement of Soft Soil
By Yudhi Lastiasih and Herman Wahyudi
ABSTRACT: The HWYL method is one of the analytical methods for predicting the amplitude and time of settlement that occurs, based on the field observations using a settlement plate or extensometer. The data used for the analysis was the result of observations from a settlement monitoring instrument of some road embankment and reclamation projects on soft soil in Indonesia. The data was analyzed using a statistical approach to determine the behavior and correlation of settlement amplitude versus time curve shape. This method obtains an equation formula to predict the consolidation amplitude and when the final settlement of last embankment occurred
Keywords: Consolidation settlement, settlement instrument monitoring, soft soil.
Bearing Capacity and Settlement Study on Small-Scale Piled-Raft Groups in Sand
By Sengara, IW., Roesyanto, Krisnanto, S., Jayaputra, A. A., and Irsyam, M
ABSTRACT: Pile group foundation with a pile cap can be considered as a piled-raft foundation. Previous studies indicate that in a piled-raft foundation, the piles contributes to reduce settlement of the raft whereas the raft provides an additional bearing capacity of the pile group. Laboratory testings were performed to investigate the performance of piled-raft group from bearing capacity and settlement point of views. Instrumented laboratory models of 2×2 and 3×3 piled-raft group were loaded vertically to obtain load vs. settlement curves and load-transfer to raft, to pile shaft, and to pile tip. From the load-settlement curves of piled-raft group, the performance of bearing capacity and settlement was then observed and quantified. The laboratory test results indicated that the presence of piles reduced the settlement of raft significantly, whereas the presence of raft provided additional bearing capacity to the pile.
Keywords: Piled-raft group, Small-scale test, Instrumented test, Bearing capacity, Settlement.
Influence of Two Rough Parallel Joint Surface Profiles on Stress Wave Energy Dissipation
By Yexue Li, Hongke Pan, Li Qinand Jianhui Fan
ABSTRACT: A new method called YUV dimension is proposed to describe joint surface configuration on the basis of the interdisciplinary theory of iconography, graphics, and fractal geometry. This method can be used as substitute for traditional fractal dimensions. On this basis, the influence of two joint surface profiles (described by using the YUV dimension method) on stress wave energy dissipation is investigated by split Hopkinson pressure bar on embedded rough parallel two-joint rocks. The following conclusions are drawn: (1) the YUV dimension method, a new approach for characterizing surface configuration, exhibits more advantages than the traditional dimension; (2) the energy dissipation of the joints increases with increasing two-joint dimensions or their sums. This increase is attributed to the fact that the increase in YUV dimensions leads to the decrease in rock joint stiffness; thus, a decrease in rock joint stiffness leads to the increase in stress wave energy dissipation. A nonlinear relationship also exists among two YUV dimensions and energy dissipation. The nonlinear relationship is attributed to the nonlinear deformation of the joints. For engineering applications, a two-variable function between the energy dissipation and YUV dimensions of two joints is also formulated.
KEYWORDS: Energy dissipation, Stress wave, YUV dimension, Two joints, Surface configuration
Failure Mode for Creep Area of High Open-pit Slope Under the Influence of Underground Mining
By Wang Ning, Zhou Xiaolong, Zhu Dengyuan
ABSTRACT: With mining intensity increasing, more and more deep open-pit mines are gradually transformed to underground mining in China nowadays. Focusing on a high open-pit slope under the influence of underground mining, the spatial distribution and development trend of slope displacement monitoring data were analyzed, combined with calculation of slope stability under different engineering conditions. The results show that the slope deformation has a periodic change with the seasons, and the rainy season is the most intense period of deformation development, when the tensile cracks on the third-level platform of the slope become penetrating channel for rainwater. The slope stability coefficient of the creep area under the unsaturated condition is 1.010 and the most dangerous sliding surface is located in the upper part, while potential sliding zones might be linked together and local slip might develop into overall failure in the role of heavy rainfall, and reasonably slope cutting can largely improve the slope stability. By studying the deformation process of the creep area, the deformation development characteristics and possible failure modes are got, and it could provide guidance to the reinforcement measures of landslides and ground subsidence.
KEYWORDS: Open-pit slope, Creep area, Underground mining, Stability analysis, Failure mode
By Nabil Ismael and Hasan Al-Sanad
ABSTRACT: The abundance of waste tires in Kuwait created a major problem requiring disposal sites and causing environmental and safety problems especially in the summer months as the temperature often exceeds 500C. Numerous fires have occurred causing air contamination and health hazards. To find useful uses of ground tire rubber an extensive laboratory testing program was carried out using rubber aggregates produced locally as additive in small quantities up to 20% by weight to the local surface sands of Kuwait. Testing included grain size, unit weight, Modified Proctor compaction, permeability, direct shear, consolidation, and CBR tests. The effect of increased rubber content on the different properties was measured. The results indicate a reduction of the density and CBR, an increase in the permeability and compressibility and no change in the angle of friction with increasing rubber content. Therefore, the use of rubber additive is beneficial for many practical applications such as light weight fill, as a drainage layer, and on the grounds of sporting facilities, and in embankment construction.
KEYWORDS: Desert sands, Soil properties, Soil tests, Ground tire rubber, Fill, Waste disposal.
A Study on Behaviour of Vertical Pile in Sand under Uplift Load
By R. Saravanan and P.D. Arumairaj
ABSTRACT: The significant design parameter for supporting the piles and the ground anchors for tension loads and compressive loads is shaft resistance. Steel pipe piles often mentioned as cylindrical piles are used often in offshore projects and in harbor structures. Since the end condition of the cylindrical piles (open and closed end) plays a significant change in the shaft capacity of the pile, an experimental study is proposed to predict the load displacement characteristics of single vertical pile subjected to uplift load. The pile is embedded in sand with varying relative densities. The analytical study was developed based on the failure mechanism from limit equilibrium technique. The present study takes into account of significant parameters such as length, diameter and as surface characteristics of pile. The axial load-displacement behavior of vertical pile is studied under the different length to diameter (L/d) ratio which is adopted for the experimental analysis. The uplift co-efficient (Ku) is evaluated by using ultimate uplift capacity load. The obtained experimental results were compared with the reported data to elucidate the significance of the work done.
ABSTRACT: Uplift coefficient, Load-displacement response, Soil-pile interface reaction, Load transfer mechanism, Internal friction angle.
Numerical Simulations of K0 Triaxial Tests on Collapsible Porous Clay
By J.C. Ruge, A. López, F.A. Molina-Gómez, R.P da Cunha and J.E. Colmenares
ABSTRACT: This paper addresses numerical simulations of K0 triaxial tests performed using a single element program. The methodology was based on construction of numerical models with three different constitutive models in order to represent the soil behaviour during stress path states. The constitutive models used were (i) the Mohr-Coulomb, (ii) the Cam-Clay, and (iii) a hypoplastic model. The material used was a collapsible porous Brazilian clay. The values obtained were compared and calibrated with experimental data. Results show that it is possible to assess soil behaviour via a single element program and that triaxial K0 stress path tests can be simulated with numerical methods. Results show that it is possible to replicate and calibrate soil behaviour under zero lateral displacement using computational tools.
Keywords: Constitutive models, K0 Triaxial tests, Numerical test simulation, Single element program, Stress path
