Geotechnical Engineering Aspects Research Articles

Small Strain Shear Modulus Equations for Zeolite–Cement Grouted Sands

Cement production is an energetically demanding process and one of the most important sources of CO2 emission in the world. Therefore, replacing part of the cement with more environmentally friendly supplementary materials such as natural zeolite (NZ) is of great importance. The small strain shear modulus (G0) of soils is an essential parameter in many aspects of geotechnical engineering. In the present study, ninety-two bender element tests on loose sandy soils grouted with cement and NZ was conducted to obtain equations for predicting the G0 of grouted sands. Multiple linear regression (MLR) and Group Method of Data Handling (GMDH) polynomial NN were used to estimate the G0 of zeolite–cement grouted sands. The G0 was modeled as a function of the average sand grain size (D50) as well as the percentages of cement replacement with zeolite (Z) and water to cementitious material ratios (W/CM) of grout. Also, the parameter active compounds (AC) was considered as one of the input parameters instead of the simultaneous effect of W/CM and Z. The results showed that both MLR and GMDH models, in which AC was considered as an input parameter to predict the G0 of grouted sands, has a much better performance than the same models with W/CM and Z as input parameters. The GMDH-based equations are more efficient than the MLR-based equations. Applying the AC as an input parameter to predict the G0 of grouted sands by the GMDH models leads to about 35–41% improvement in G0 prediction. Therefore, the AC is a very effective parameter for estimating the G0 of the grouted sands. The GMDH-based predicted G0 is significantly affected by changes in zeolite percentage and the effect of sand particles’ size variation on the accuracy and variation of the predicted G0 is less than the other two parameters (W/CM and Z).

Geotechnical Engineering Aspect Related to Pidie Jaya–Aceh Earthquake Disaster and Mitigation

Earthquake catastrophe in Pidie Jaya has caused damages to the city of Meureudu, Aceh-Sumatra Indonesia. Based on preliminary study for buildings and infrastructures, the geotechnical engineering aspects damages-related are presented. Seismic motion effect damage of earthquakes such as liquefaction of soil, lateral spreads, and ground failure were the majority effect for infrastructures and buildings. Moreover, failures of almost of multi-storey buildings and mosques along the national road lines are because the effect of peak surface accelerations and earthquake wave propagation forces which are very close with epicenter coordinates 5.308 ° N / 96.269 ° E in 4km radius. Seismic back investigates of the Aceh’s fault seismic source as well as initial probabilistic seismic hazard analysis post-Pidie Jaya earthquake for city of Mereudu is offered. Liquefaction potential analysis from the estimation of peak ground acceleration was conducted. Geotechnical aspect and substructure failure characteristics to infrastructure and housing damages due earthquake are also reported. The earthquake has caused 104 people deaths, 2.474 unit houses in total need to be rehabilitated and rebuilt, almost 10 km of roads and 50 bridges need to be reconstructed. Some descriptive countermeasures for reconstructions of geotechnical engineering aspects and mitigation are also provided.

Reconnaissance Report on Geotechnical Engineering Aspect of the 2015 Gorkha, Nepal, Earthquake

ABSTRACTAn earthquake of moment magnitude Mw 7.8 struck Nepal at 06:11 UTC on April 25, 2015. Field reconnaissance focused on the geotechnical engineering aspect of the earthquake was carried out in the Kathmandu Valley and regions near the epicenter. This paper presents briefly the geology of Nepal, the accelerogram, and results of standard penetration tests at selected sites in the valley. The study shows the failure case histories including landslides, road embankment settlement, bridge foundations and abutment damage, and liquefaction. The paper also highlights the impact of local soil properties and basin and ridge effect on the severity of damage.

Applications of Particle Swarm Optimization in Geotechnical Engineering: A Comprehensive Review

Particle swarm optimization (PSO) is an evolutionary computation approach to solve nonlinear global optimization problems. The PSO idea was made based on simulation of a simplified social system, the graceful but unpredictable choreography of birds flock. This system is initialized with a population of random solutions that are updated during iterations. Over the last few years, PSO has been extensively applied in various geotechnical engineering aspects such as slope stability analysis, pile and foundation engineering, rock and soil mechanics, and tunneling and underground space design. A review on the literature shows that PSO has utilized more widely in geotechnical engineering compared with other civil engineering disciplines. This is due to comprehensive uncertainty and complexity of problems in geotechnical engineering which can be solved by using the PSO abilities in solving the complex and multi-dimensional problems. This paper provides a comprehensive review on the applicability, advantages and limitation of PSO in different disciplines of geotechnical engineering to provide an insight to an alternative and superior optimization method compared with the conventional optimization techniques for geotechnical engineers.

The Degenerate Mechanism of Sand-Concrete Interface under Cyclic Loading

The sliding interaction between the sand and the surface of the structure is involved in many aspects of geotechnical engineering and is particularly important for the derivation of the shaft capacity of piles. A constant normal stiffness direct shear apparatus is designed and applied herein to research the soil-structure interface weakening mechanism under cyclic loading. The test results show that the sand-concrete shear stress and normal stress change in the Hysteresis loop and Butterfly trends with shear displacement respectively in a complete shear cycle. The difference of adjacent Hysteresis loop or Butterfly is evident in the initial stage of cyclic shear, but tends to gentle after 15 cycles. The evident decays of both the shear stress and the maximum normal stress take place during cyclic shearing, which is approximately logarithmically with the shear cycles. The shear strength of the interface is approximately linear with the normal stress under different cycles. The percentage of particle breakage is between 5.5% and 6% of the original sand after 20 shearing cycles. The percentage of particle breakage and the degeneration rate of shear stress and normal stress increase with the increase of the initial normal stress and the amplitude of shear displacement.

철도 레일빔 설계법에 대한 연구

본 논문은 레일빔의 길이 산정에 관해서 지반공학적 측면에서 다룬 내용을 담고 있다. 레일빔은 철도횡단공사에서 가설기간 중에 부등침하 방지 목적으로 레일의 내측과 외측에 설치하는 보강레일을 말한다. 이러한 레일빔은 최근 철도를 횡단하는 지하 구조물의 시공이 증가해서 기존 철도 시설물의 안정에 대응하고자 많이 설치하고 있다. 그러나 레일빔 길이 설계에 관한 기준이 없어 설계에 어려움이 있을 뿐만 아니라 레일빔 길이 부족으로 탈선사고까지 이어지는 경우가 발생하고 있다. 따라서 본 연구에서는 레일빔 길이 산정 방식에 대하여 토사지반과 암반지반으로 분류하여 Flow chart를 제시하였으며 레일 조합 및 위치에 대한 Case study를 실시하여 효과적인 레일의 조합과 위치에 확보할 수 있었다. This paper deals with contents on the estimation of rail beam from the geotechnical engineering aspect. Rail beam is reinforced rail installed on the inside and outside of rail to prevent differential settlement during the construction period of railroad crossing construction. Such rail beam is frequently being installed to ensure stability of existing railroad facilities because of increasing constructions of underground structures crossing railroad in recent. However, there is a difficulty in design due to lack of design standard on rail beam length. Furthermore, derailing accidents are also occurring as a result of rail beam length shortage. Accordingly, this paper presented flow chart based on the classification into soil ground and bedrock ground for the rail beam length estimation. In addition, case study was conducted on rail combination and location through which effective rail combination and location were ensured.

Environmental geotechnics in the US region: a brief overview

The present contribution to the Regional Editors themed issue offers a concise yet focused overview of some of the key technical and scientific issues, as well as of current trends and future challenges, related to the broad discipline of environmental geotechnics in the US region. Particular attention is devoted to current policy and societal drivers as well as future professional and research capacity requirements in critical areas such as innovative recycling and improvement of compost, construction and geologic materials; solid waste management, landfilling and geoenvironmental remediation techniques; and crucial geotechnical engineering aspects of renewable energy production, storage and distribution.

실내실험과 현장실험을 통한 Methylene Blue 동결깊이 측정장치 신뢰성 검토에 관한 연구

동결깊이는 영구 동토지역 및 계절성 동토지역에서 도로의 동상방지층, 매설관의 깊이 및 건물의 기초를 설계하는데 중요한 고려사항이다. methylene blue 동결깊이 측정장치는 지중 온도센서를 이용한 계측시스템과 비교하여 저렴하고 유지관리와 측정이 용이한 장점을 지니고 있다. 그러나 지반공학적 관점에서 지중에 매설된 methylene blue 동결깊이 측정장치의 신뢰성을 검토한 연구는 미미하다. 본 논문에서는 실내실험과 현장실험을 통해 methylene blue 동결깊이 측정장치의 신뢰성을 검토하고, 나아가 국내 현장에서 검증된 측정장치로 장기간 측정된 동결깊이 실측 데이터를 이용하여 최대 동결깊이 분포도를 작성하였다. 본 연구를 바탕으로 실측된 동결깊이는 향후 국내 지반구조물 설계에 중요한 자료로 활용될 수 있을 것으로 판단된다. The frost depth is one of important factors in the design of structures such as roadways, buried pipeline, and foundations. A frost indicator with methylene blue solution has several advantages with respect to installation cost, maintenance, and simple measurement. However, as a geotechnical engineering aspect, the accuracy of the frost indicator has not been proved yet. This paper presents experimental and field investigations of the accuracy of the frost indicator and contour maps of maximum frost depth. The contour maps of maximum frost depth can be applied to design geo-infrastructure in South Korea.

CPT based prediction of foundation penetration in siliceous sand

The load–penetration response of a foundation is one of the fundamental aspects of geotechnical engineering. In sand, the bearing capacity approach requires the operative friction angle to be known, which introduces significant uncertainty to the prediction. The predictive method developed in this paper eliminates the need to determine the friction angle. The central concept is the direct correlation of in situ piezocone penetrometer measurements to the load–penetration response of foundations.The correlation factor is shown to depend primarily on the sand relative density. The footing shape has a minor influence on the correlation factor. This study aims at large diameter foundations used in the offshore industry, where the variation in correlation coefficient is minor. However, context is provided to previous research on smaller diameter foundations, which shows the dependence on the footing diameter (through the well-known stress level effect).The proposed method is shown to perform well against load–penetration data from centrifuge experiments on footings of different diameters and elevation shapes. The performance against field data in particular provides significant confidence in the CPT based prediction method of foundation penetration in sand developed here.

Geotechnical engineering aspects of the catastrophic Tohoku (Japan) earthquake of March 11, 2011: the review of first results

Geotechnical engineering aspects of the catastrophic earthquake, which occurred in Japan on March, 11, 2011 and called Tohoku earthquake are discussed. A review is presented of the first results obtained mainly by Japanese scientists based on records of seismic networks of Japan K-NET, Kik-net and on GPS data. The basic concepts of seismic zoning in Japan and the location of the Tohoku-oki earthquake on the seismic zoning maps are described, as well as models of the source process obtained by various authors based on teleseismic data, strong motion data, GPS data, and tsunami observations. The recorded peak accelerations and velocities and their correspondence to the current empirical attenuation curves are discussed. The records of the Tohoku earthquake made by Japanese seismic networks K-NET, Kik-net and some others represent unique seismological material and the most complete seismic database (including vertical array records) in the near-source zone of a strongest earthquake with magnitude Mw = 9. These data will be studied by seismologists all over the world for many years and, probably, they will answer many questions of geotechnical seismic engineering.

Design Procedure and Considerations for Piers in Expansive Soils

The design of pier foundations in expansive soils is an important and challenging aspect of geotechnical engineering. Established methods for pier analysis include rigid and elastic methods. These methods have certain limitations that restrict their applicability to evaluate certain complex aspects of pier heave, including variable soil profiles, complex wetting profiles, large length-to-diameter ratios, and complex pier configurations and materials. To address those limitations, a method of analysis was developed providing a versatile and robust tool to predict both pier heave and axial forces developed by expansive soils. This method utilizes a standard finite-element code to solve for pier heave and force in the pier for the given boundary conditions. This paper contains both a discussion of the general design procedure and the finite-element formulation. This design procedure, including the finite-element code, accurately determines pier heave and force in a pier compared with field-measured data. The design procedure and the finite-element code in particular, address the limitations of the established rigid and elastic pier analysis methods with the flexibility to evaluate complex design situations. A comparison with field-measured pier heave and tensile force in the pier demonstrates that the design procedure accurately models both the magnitude of pier heave and force in the pier. The results obtained using this design procedure have been compared with those obtained using the established pier analysis methods for simplified drilled pier examples. The comparison of the various methods of analysis demonstrates that the finite-element design procedure predicts pier heave values that are generally less than the existing elastic and rigid pier analysis methods. It is believed that the proposed design method is more realistic and provides a design tool with improved accuracy compared with existing methods.

Geological storage of high level nuclear waste

The quantity of radioactive waste will grow significantly with an increasing interest and use of nuclear-generated energy. There will always be inevitable radioactive waste residues that require disposal, even using an advanced nuclear fuel cycle in the future. Deep geological disposal, one of the most promising final disposal methods, should be validated for its long-term performance and safety assessment. Geotechnical issues related to the deep geological disposal are critical for the sustainable development of nuclear energy. They play challenging roles especially under extreme circumstances that result from deep geological conditions of a repository, extremely long containment time, and the characteristics of nuclear waste itself such as high decay heat, which may primarily affect thermo-hydro-mechanical and geochemical-coupled behavior of a repository for geologic time scales. This paper introduces an overview of deep geological disposal concepts based on Finnish, Korean, Spanish, and Swedish disposal programs, discusses the outstanding research issues in disposal from the aspect of geological and geotechnical engineering, such as Excavation-Damaged Zone (EDZ), cementitious material, long-term gas migration, and self-sealing/healing of fractured rocks with a focus on the state of the art in-situ validation experiments, and additionally presents a numerical modeling of the coupled THMG process in the repository near field, which is one of the major factors concerning the fuel canisters.

Recent advances in offshore geotechnics for deep water oil and gas developments

The paper presents an overview of recent developments in geotechnical analysis and design associated with oil and gas developments in deep water. Typically the seabed in deep water comprises soft, lightly overconsolidated, fine grained sediments, which must support a variety of infrastructure placed on the seabed or anchored to it. A particular challenge is often the mobility of the infrastructure either during installation or during operation, and the consequent disturbance and healing of the seabed soil, leading to changes in seabed topography and strength. Novel aspects of geotechnical engineering for offshore facilities in these conditions are reviewed, including: new equipment and techniques to characterise the seabed; yield function approaches to evaluate the capacity of shallow skirted foundations; novel anchoring systems for moored floating facilities; pipeline and steel catenary riser interaction with the seabed; and submarine slides and their impact on infrastructure. Example results from sophisticated physical and numerical modelling are presented.

Simplified Dynamic Finite-Element Analysis for Three-Dimensional Pile-Grouped-Raft-High-Rise Buildings

Combined with the respective advantages in S-R(Sway-Rocking) impedance concept and finite-element method, a simplified 3D structural dynamic FEM considering composite pile-group-soil effects is presented. The structural members including piles are modeled by spacial beam or shell elements, and raft-base is divided into thick-shell elements with its spring-dashpot boundary coefficient obtained by impedance backcalculated. The mass-spring elements for soil between piles are set to simulate vertical, horizontal pile-group effects by strata-equivalent approach. The soil beside composite body is separated into near-field and far-field parts. The former is modeled by nonlinear spring-dashpot elements based on Winkler’s hypothesis, while the latter is modeled by a series of linear mass-spring-dashpots. With the effects of boundary track forces and energy radiation, the presented model enables researchers to conduct the time-domain nonlinear analysis in a relatively simple manner which avoids sophisticated boundary method and solid-element mesh bringing with tremendous computational cost. The seismic effect on dynamic interaction of pile-soil-complicated structures would be efficiently annotated from two structural engineering and geotechnical engineering aspects and the numerical calculation effort would be drastically decreased too. The complete procedure is mainly performed using the parametric design language assembled in the Finite Element Code Ansys. With the dynamic analysis of foundation and superstructure for a pile-supported 15-storey building, the influence of the participant effect on structural dynamic response will be depicted by various dynamic parameters of pile-soil-raft foundation in detail. Not only do the results have an agreement with some conclusions drawn by the general interaction theory, but also certain of phenomena which would be disagree with that by general analysis is involved. Even with the finite-element meshes for 68 piles, the time-history analysis procedure for PGSS (Pile-Group-Soil-Superstructure) system and the qualitative evaluation with various SSI parameters can be also fulfilled efficiently and rapidly by presented means. These results may be of help to the designers to quickly assess the significance of interaction effect for the high-rise buildings resting on any type or layout of pile-group foundation.

Geo-Seismic Environmental Aspects Affecting Tailings Dams Failures

Seismic performance evaluations of tailings dams are essential for characterizing the geo- environmental risks posed by these earthen structures, which should include the geotechnical hazards implied by slope instability failure, free board loss and the potential release of contaminants. The observed damage is more important when liquefaction occurs on the dam body and foundation, which often leads to cracking, settlements, tilting and general distortion of dam geometry. Analyses based on limit equilibrium are generally sufficient to establish hazard zones. However, numerical models with solution schemes formulated in the time domain, which are capable of taking into account the kinematics of soil movement more realistically, are needed to quantify the geotechnical risk. This paper reviews the main geotechnical earthquake engineering aspects to account for when designing tailings dams and describes the application of a practice-oriented simplified constitutive model, which implemented in a lagragian finite difference platform, is capable of predicting the accumulation of pore pressure in fine-grained saturated materials due to earthquake loading, the reduction of shear strength and the corresponding permanent displacements. The model uses the Mohr-Coulomb failure criterion coupled with an incremental pore pressure generation scheme. Pore pressure is accumulated as a function of the number of stress cycles. The secant soil stiffness and hysteretic damping change with loading history. The numerical simulation is able to properly capture the kinematics of dam failure and provides the parameters to assess potential environmental impacts on the nearby areas of the dam.

Survey of Geotechnical Engineering Aspects of the December 2004 Great Sumatra Earthquake and Indian Ocean Tsunami and the March 2005 Nias–Simeulue Earthquake

Reconnaissance surveys of building and infrastructure damage related to geotechnical engineering aspects were conducted four to six weeks after the 26 December 2004 earthquake and five weeks after the 28 March 2005 earthquake. These surveys identified many instances of building collapse and infrastructure damage that were probably caused by strong ground shaking and/or liquefaction-induced foundation or embankment failures. The survey results suggest the need for earthquake engineering research that identifies likely future earthquakes and their ground motion characteristics. Because of the observed variation in the level of damage, a seismic microzonation study should be performed to identify the spatial variability of strong ground shaking for the purpose of reconstruction and future planning of cities in Nangroe Aceh Darrusalam Province and Nias Island.

Geotechnical and Structural Damage in Tamil Nadu, India, from the December 2004 Indian Ocean Tsunami

A reconnaissance team surveyed the geotechnical and structural engineering aspects of tsunami damage on the coast of Tamil Nadu in India. The area surveyed was from Chennai on the east coast to Thiruvananthapuram on the west coast. There was practically no major evidence of damage from direct ground shaking, although damage from the tsunami was extensive. The geotechnical engineering damage observed was mostly due to erosion of soil, settlement of soil, damage to port and harbor facilities, and damage to lifelines. The structural engineering damage involved damage to compound walls, collapse of rural houses, failure of columns, and toppling of roofs; some of the damage occurred because reinforcement details were lacking. Analyses of damage and its causes were performed, and the level of damage correlated well with the tsunami runup for the localities visited.

Geotechnical Engineering Aspects of the June 1999 Central Mexico Earthquakes

An earthquake of moment magnitude (Mw) 7.0 struck the central region of Mexico on 15 June 1999 between the states of Puebla and Oaxaca. A second event with a moment magnitude 6.3 occurred on June 21, also affecting the central region of Mexico but with minor consequences. Attenuation relationships of peak ground acceleration with hypocentral distance for the June 15th event were compared with strong-motion recordings over a variety of geologic site conditions. Significant site amplification was observed and was correlated with deep soil conditions. The June 15th event caused significant damage of unreinforced masonry structures, such as churches and houses, including more than 500 historical buildings. Puebla City and the towns of Tehuacán and Acatlán de Osorio were the urban areas hardest hit by the earthquake. Although the earthquake was felt in Mexico City, the damage was light and mostly restricted to nonstructural elements. Comparison with observations obtained during the September 1985 earthquake suggest that significant soil nonlinearity, resulting in increased amplification at larger periods, can be observed for soft soil sites.

Briefing: What is the matter with geotechnical engineering?

In this essay the author argues that education in the basic theory of structures, hydraulics and geotechnics is being neglected in favour of training in the practical aspects of geotechnical engineering and an over-reliance on design codes and standards.

What is the matter with geotechnical engineering?

In this essay the author argues that education in the basic theory of structures, hydraulics and geotechnics is being neglected in favour of training in the practical aspects of geotechnical engineering and an over-reliance on design codes and standards.