Integrating Geotechnical Investigation with Hydrological Modeling for Mitigation of Expansive Soil Hazards in Tabuk City, Saudi Arabia

Due to global climatic changes, flash floods are followed as a yearly disaster with high magnitude of influence. During the years 1981, 1988, 2010, 2012 and in January 2013, Tabuk city, northwest of Saudi Arabia suffered huge flash floods. These are major factors affecting on the swelling behavior of expansive Tabuk shale. The examined geotechnical properties of the surface and subsurface lithology of the sedimentary deposits distinguished Tabuk city into three zones. The expansive zone is spread in the middle and the non-expansive zones are distributed in the east and west of the city. The Watershed Modeling System (WMS) and Hydrologic Engineering Center (HEC-1) models were used to delineate and identify the drainage system and basin morphometry, where flash floods and accumulation of water might take place. Integration between geotechnical distribution maps of the expansion soil and surface hydrological data in terms of runoff maps was done. It has been identified the whereabouts the soils which have expansion characteristics and areas prone to flooding and surface runoff. They are helpful in defining the hazard zones map. Based on this map, it can be avoided constructions on the risk neighborhoods such as Al Qadsiyah, Al Maseif, Arrwdah, Al Nakhil and Al Rajhi. Also, it can suggest that the western side of Tabuk city is suitable for future urban extension. These results will help planners and citizens to create alternative development scenarios and determine their impact on the future urbanization patterns. Moreover, the direction of surface runoff flow or storm water discharge should be away from the expansion soil areas. Therefore, constructing dams on the outlet of the high-risk basins, south of Tabuk city is an important solution to control flash flood events, as well as increase groundwater recharge.

Development of Finite Element Limiting Analysis Method and Its Applications in Geotechnical Engineering

The Finite Element Limiting Analysis Method(LELAM) has the advantage of combining a numerical analysis method with traditional limiting equilibrium methods.It is particularly applicable to the analysis and design of geotechnical engineering.In the early 20th century,FELAM has been developed vigorously in domestic geotechnical engineering over international common finite element procedures.It has made great achievements in basic theory research and computational precision,thus broadening the application fields in practical projects.In order to gradually make innovations in geotechnical design methods,some of our research results are presented,mainly including geotechnical safety factor definitions,the principles for use of the method concerned,the overall failure criterion,the deduction and selection of the yield criterion,and the measurement to improve the computational precision,etc..The application field has been broadened from two-dimensional to three-dimensional,from soil slope to jointed rock slope and foundation,from stable seepage to non-stable seepage,from slope and foundation to tunnel.This method has also been used in search of many hidden sliding surfaces of complex landslides,conducting the structural support design considering the interaction between the soil and the structure,and computing simulation foundation bearing plates load tests,etc..

Geotechnical Characterization of Sakakini’s Palace Stones and Other Construction Materials, Cairo-Egypt

The understanding of the geotechnical problems and failure mechanisms of stone structures of Sakakini palace (1897 after century) entails a comprehensive study on the mechanical behaviour of the stones and other construction materials. In addition to micro analysis, geological and geomorphologic interests, several investigations on stone deterioration and engineering geology were performed, First phase included more sophisticated techniques, which provided additional information on particular aspects of site deterioration and it included laser induced breakdown spectroscopy (LIBs), electron probe micro analysis, micro XRD and XRF analyses, scanning electron microscope analysis coupled with EDX probing, transmission electron microscopy and grain size distribution analysis, permeability and pore size distribution of stone, mortars, core binders and other construction materials. Second phase included the determination of mechanical properties of building stones, such as compressive strength, modulus of elasticity, tensile strength, and shear strength. To arrive at reliable values for these properties, a suitable number of samples should be extracted, prepared for testing, and properly tested. The test results are then analyzed to establish the investigated stone properties. The testing program includes extracting seven cylindrical cores from the basement stone walls of Sakakini’s mansion in down townCairo. The cores are extracted using rotary cylindrical diamond blade coring machine. The top and bottom surfaces of every core were prepared to be flat circular surfaces perpendicular to the vertical axis of the core. Because the palace is museum and attractive places for the tourists, core sampling could be carried out only at a limited number of locations under official permission. For the purpose, cylindrical specimens with a diameter of 42 - 44 mm and height of 90 - 100 mm, prepared by the use of a core drilling machine and some collected blocks from the archaeological site under investtigation were taken to determine the bulk structure, physical, short and long-term mechanical properties of the stone and other construction materials in the laboratory. A number of specimens prepared from these blocks were employed for testing. Furthermore, limitation due to the number of blocks was overcome by the determination of the in situ characteristics of the stones by Schmidt hammer tests, geo-tomographic investigations and rock mass classification on some stone rock structures where testing has been permitted. The objectives of the study are to provide a characterization of micro structures and the mechanical properties of the stones of Sakakini’s Mansion;describe the required testing plan;describe the test results and conclude the values of the basic mechanical properties of the building stones. The following sections provide detailed descriptions of the steps taken to achieve the objectives of the study. The purpose of the present research is to provide recommendations regarding the strengthening and the safety of architectural heritage under long and short-term loading. For this purpose, a set of experimental tests and of advanced numerical analyses are to be carried out.

Importance of Geotechnical Investigation for Design and Construction of Shafts over 1000 m Deep

In most cases, copper ore deposits occur at great depths, so the optimization of excavation costs is of utmost importance to identify the most cost effective and productive mining methods, such as block caving or similar methods specifically developed for these deposits. To be able to apply such methods, it is necessary to have a detailed knowledge of the rock mass in terms of its geomechanical, engineering geological and hydrogeological characteristics. This research aims to reduce geological and geotechnical unknowns, analyze in detail the geological environment, and predict geotechnical conditions for the construction of the shaft. This paper uses the example of Borska Reka Copper Deposit, located in Serbia to illustrate the importance of geotechnical investigation to enable best practice in design and construction of shafts that are over 1000 m deep.

Probabilistic back analysis for geotechnical engineering based on Bayesian and support vector machine

Geomechanical parameters are complex and uncertain.In order to take this complexity and uncertainty into account,a probabilistic back-analysis method combining the Bayesian probability with the least squares support vector machine(LS-SVM) technique was proposed.The Bayesian probability was used to deal with the uncertainties in the geomechanical parameters,and an LS-SVM was utilized to establish the relationship between the displacement and the geomechanical parameters.The proposed approach was applied to the geomechanical parameter identification in a slope stability case study which was related to the permanent ship lock within the Three Gorges project in China.The results indicate that the proposed method presents the uncertainties in the geomechanical parameters reasonably well,and also improves the understanding that the monitored information is important in real projects.

The Use of Ground Penetrating Radar in Municipal Solid Waste Landfill Geotechnical Investigation

The use of GPR （ground penetrating radar） as an auxiliary tool in geotechnical and environmental site investigations has increased in Brazil during the past few years. GPR has been used to delineate contamination plumes, to aid in geological modelling, to detect buried structures and in archaeological surveys. This paper describes and discusses the results ofa GPR site investigation carried out at Gramacho Municipal Solid Waste Landfill in the State of Rio de Janeiro, Brazil. A field study was conducted to detect failure surfaces in its slopes and within the waste mass. The results have shown that： （l） Slip surfaces could be indicated by small continuous voids within the waste mass since there is a good contrast between the dielectric constant of air and municipal waste; （2） Greenhouse gases pools could also be indicated by large voids within the waste mass since there is a good contrast between the dielectric constant of carbon dioxide, methane and municipal waste; （3） Leachate pools present a high electric conductivity that could be easily detected by GPR.

Determination of Potential Landfill Site in Tarkwa Area Using Multi-Criteria GIS, Geophysical and Geotechnical Evaluation

A 24-acre land at Aboso serves as the site where municipal solid waste from Tarkwa and its environs are openly dumped. Evaluation of the suitability of this existing landfill site for the construction of an engineered landfill was determined. Reconnaissance survey, structural mapping, determination of depth to groundwater, geotechnical site investigation as well as socio-economic indicators showed that the existing landfill site is not suitable for an engineered landfill construction. A multi-criteria GIS model was used to select an alternative suitable area for the construction of an engineered landfill. The multicriteria GIS modelling identified fourteen (14) suitable areas for the siting of landfill in the Tarkwa area. A site located in Domeabra was chosen due to its proximity to the neighbouring communities of Tarkwa, Nsuta and Aboso. The suitability of the proposed site in Domeabra was assessed using geotechnical and geophysical methods. The geotechnical methods included the testing of soil properties such as moisture content, particle size distribution, Atterberg limit, bulk density, specific gravity, and compactibility. The soils at Domeabra site are predominantly gravel and sand, well graded with gradual increase in clay content with depth and good moisture content (less than 30%). The gravel and sandy soils have good to excellent shear strength and work ability. The soils in Domeabra have suitable dry density (1.3 - 2.1 Mg/m3), bulk density (1.7 - 2.5 Mg/m3) and specific gravity (2.2 - 2.9) for landfill construction. The geophysical method involved the use of seismic refraction tomography. The geophysical survey showed that the site is made up of four layers namely the top soil (0.5 - 2 m), weathered material (5 - 15 m), saturated material (10 - 15 m) and fresh rock. The water table occurs at a depth of 12 to 15 m. The proposed area in Domeabra based on the geophysical and geotechnical investigations is suitable for the construction of engineered landfill.

Permafrost and geotechnical investigations in Nalaikh Depression of Mongolia

Mongolia is a land-locked country in Central Asia, located between Russia and China. The country＇s high altitude results in cold, dry, and harsh climatic conditions with permafrost being widespread through the territory. Although the capital city Ulaanbaatar is situated in an area with discontinuous permafrost, the downtown section has recently seen a disappearance of permafrost due to an underground central heating system. During the last decade, expansion of the suburbs toward the Nalaikh Depression has resulted in construction of a new residential complex （Urgakh Naran）, construction materials trading center, cement factory and agricultural products market. In the next 10 years, projects such as a university campus, logistics center, residential complex, railway and highway extensions connecting Russia and China have been planned. Engineering-geological and geotechnical investigations have been conducted for these construction projects. This paper presents some of the results determining the engineering geocryological conditions of Nalaikh district and offers foundation design options.

近2年我国隧道及地下工程发展与思考(2017—2018年)

概述我国隧道及地下工程近2年的发展情况,包括铁路隧道、高速铁路隧道、公路隧道、地铁隧道、水工隧洞及综合管廊;并对铁路、公路、市政等方面的重大典型工程进行具体介绍,包括兰渝铁路木寨岭隧道、敦格铁路当金山隧道、港珠澳大桥沉管隧道、中老铁路隧道、大瑞铁路高黎贡山隧道、成兰铁路跃龙门隧道、乌尉高速天山胜利隧道、深中通道、汕头苏埃通道、引额供水项目喀双隧洞、深圳前海综合交通枢纽工程、武汉光谷广场地下综合体等。总结近2年来我国在隧道工程勘察技术、隧道建设的BIM技术、/TBM制造及再制造技术、海上沉管隧道修建技术、异形盾构隧道修建技术、隧道大数据平台建设技术等方面取得的发展。依据川藏铁路、京津冀协调发展、长江经济带、粤港澳大湾区等一系列国家发展战略、规划的启动与实施,分析各个方面对隧道及地下工程领域提出的技术需求,包括:跨海隧道修建技术、复杂条件超长隧道修建技术、生态脆弱区隧道施工环保技术、城市地下大型综合体开发、高寒环境新材料研发、隧道病害智能诊断与快速修复技术、超长复杂隧道及地下工程智慧防灾技术等。最后,结合行业发展现状,从如何提升隧道工程建设管理理念和如何深入推进钻爆法机械化施工进程2个方面对行业发展提出思考和建议。

Application of data analysis method in geotechnical engineering

Geotechnical seismic engineering belongs to the cross field of geotechnical engineering and earthquake engineering. Due to the dual effects of the variability of geotechnical objects and the complexity of dynamic loading, the scientific problems involved in this field have to face more uncertainties. Through the analysis on the status quo of uncertainty analysis methods in geotechnical earthquake engineering in the field of non deterministic analysis clear difficulties, weak links with all kinds of uncertainty analysis method to solve the inherent weakness of determining geotechnical earthquake engineering uncertainty problem, and can determine the establishment and improvement to provide some ideas and direction analysis model for non.

Geotechnical research on Jiangnan Tu-Dun tomb historical remains in China

Geotechnical research on historical remains can provide new data and distinctive viewpoint for research on soil mechanics. Two Jiangnan Tu-Dun tombs historical remains were investigated by means of in situ and laboratory geotech-nical tests. In the present paper the geotechnical properties of these man-made earthworks, especially ageing effect on consolidation and direct shear, and compaction properties of earth fill are discussed.

东北振兴中的若干环境岩土工程问题

振兴东北老工业基地面临许多环境岩土工程问题,如固体垃圾处理、采空区建设、土壤污染等。这些问题不仅关系到投资环境的改善和经济振兴,同时也密切关系着普通百姓的生活质量。如何做到经济发展与环境保护双赢是经济建设者和岩土工作者不可推卸的责任。本文对上述环境岩土工程问题进行了探讨并提出了基本对策,力图能使该问题引起人们的足够重视。

Hydrogeological Hazards and Control Measures in Engineering Geological Exploration

For engineering geological investigation, hydrographic surveys are particularly important. By operating the equipment, relevant technicians analyze hydrogeological data around the project. A series of corresponding measures were taken to ensure the smooth completion of the project. However, due to the inadequate completion of hydrogeological survey work, it has great harm to the later stage of engineering work, and even will lead to the final failure of the project. Based on this, this paper explores the hazards and prevention measures of hydrogeology in engineering surveys.

Investigation of Critical Thinking Tendency of Engineering Students and Analysis of Teaching Countermeasures

“New Engineering”construction puts forward higher requirements for the critical thinking ability of engineering talents in the future.With“California Critical Thinking Disposition Inventory Chinese Revision”,the critical thinking tendency of engineering majors in local engineering colleges was investigated and analyzed.The results showed that the critical thinking level of the engineering students was obviously lower.According to the findings and teaching practice,this paper gives some teaching countermeasures to strengthen the cultivation of critical thinking of engineering students.

Geotechnical Properties of Some Clay Deposits in Some Parts of Southwestern Nigeria in Relation to Its Engineering Implications on Constructions

Twenty-two clay samples from Oduna,Okada,and Etsako clay deposits in Southwestern Nigeria were subjected to Geotechnical analysis to evaluate their impact on engineering,especially on construction.The results revealed that the clays deposits were majorly fine-grained texture(<60%),with Plasticity ranging from 23%to 121%,Liquid Limit(25%~205%)having plasticity of medium to very high with a specific gravity from 1.93 to 2.58.Using the American association of state highway and transportation office(AASHTO)and Unified system classification scheme(USCS),the samples fell within A-7-6(clayey soil)indicating a subgrade that is fair to poor and within the CL-CH category of fine-grained soil with medium to very high plasticity.Compaction having maximum dry density(MDD)to optimum moisture content(OMC)ranges from 0.94 g/cm^(3)~1.68 g/cm^(3)to 11.9%~44.5%,Triaxial result with cohesion between 0.33~35 and shear strength from 44~120 and California bearing ratio for unsoaked bottom 7.52~40,top 4.82~39.18 and soaked bottom 2.89~30.41,top 4.21~33.53.The geotechnical properties of the clay deposits do not meet the standard requirement hence the implication in engineering might be susceptibility to construction failures.

The Role of Geotechnical Engineering in Photovoltaic Solar Photovoltaic Energy in Arid Climate Regions

The photovoltaic solar energy is comprised of many engineering disci-plines.Geotechnical engineering is one of those disciplines in which it has important functions in the solar photovoltaic technology and particularly for large scale projects which usually employed in open areas such as parks or deserts.The aim of this paper is to present in depth the role of the geotechnical engineering in the solar photovoltaic energy and clarifying the common challenges facing this technology in arid climate regions.It is found that the lack of specialised codes and specifi cations that needed for foundation design and in selecting the proper foundation types.This would significantly affect the development of this technology in terms of efficien-cy and performance of the proposed solar photovoltaic systems.The hot weather climate and induced stresses by wind speed are also critical issues that should be considered.In order to avoid the uncertainty of data such as soil properties,the use of numerical modelling techniques is an eff ective method to help determining the most proper parameters needed for design and analyse purposes.

Analysis of Geotechnical Engineering Safety Technology in Urban Underground Space Construction

With the accelerating pace of urbanization,the development and application of urban underground space has attracted much attention.In the construction of urban underground space,geotechnical engineering safety is the key point for construction.Based on this,this paper analyzes the application of geotechnical engineering safety technology in urban underground space construction,in hope that this analysis can provide a scientific reference for the rational application of geotechnical engineering safety technology as well as the construction and development of urban underground space.

Congratulatory Letter to the Journal of Rock Mechanics and Geotechnical Engineering

Over many years now, I have had the privilege to observe China＇s spectacular growth, not only in terms of the expansive construction of infrastructural facilities built on and in rock masses, but also in terms of the associated rock mechanics and rock engineering advances. Moreover, over the years, I have enjoyed looking through the issues of the existing Chinese Journal of Rock Mechanics and Engineering （CJRME）. The content of this Journal, initiated in 1982, is partially accessible to foreigners because the Contents, paper Abstracts and Figure captions are published in English. The number of rock mechanics articles in each monthly issue of the Journal is far more than any other country can produce. This activity is also reflected in the fact that China now has more ISRM members （502） than any other country -- and the number is no doubt continuing to grow! Furthermore, the Editor-in-Chief of the CJRME, Professor Feng Xiating, will be the next ISRM President for the period 2011-2015.

JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING Instructions to authors

Aims and scope Journal of Rock Mechanics and Geotechnical Engineering （JRMGE） is a quarterly journal focused on the latest research achievements in rock mechanics and geotechnical engineering, and provides an opportunity for colleagues from all over the world to understand the current developments in rock mechanics and geotechnical engineering.

Assessing Geotechnical Risks in the Frame of Landfill Engineering in Eastern Europe

The planning of waste management facilities requires a study of design altematives including economic and environmental aspects to determine the optimal solution. Both landfill design and engineering are based on a geotechnical risk assessment namely in terms of the stability of the subsoil, the potential of mechanical deformation of the landfill body, and the stability of the interim and final cover considering also seismic events. This contribution introduces sites located in Romania and Estonia with a special focus on the geotechnical risk assessment in the design and construction of new landfills and the closure of old landfills. During the closure of a landfill an appropriate development of the interim cover is of high relevance for the remediation of old landfills, since the settlement processes in the landfill body must be decayed before the final cover can be applied. Depending on the proportion of biodegradable waste in the landfill body, the degree of compaction of the waste as well as the alteration and degree of mineralisation, the degree of the settlements can account for 5 to 15% of the landfill body height. The major settlements can generally last up to three years, depending on the organic inventory of the landfill. The examples from landfill engineering in Estonia and Romania illustrate the relevance of geotechnical assessments during the design phase of a landfill or a landfill closure as well as during the construction period.