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.

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.

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.

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.

The Effection Analysis of Geotechnical Investigation on Foundation Pit Supporting Construction

With the continuous development of the construction industry,the density of engineering construction and the difficulty of underground construction are also increasing.As an important construction protection measure,foundation pit support construction is widely used in underground construction.Starting from the characteristics of foundation pit support construction,this paper analyzes the influence of geotechnical investigation on foundation pit support construction,and analyzes the problems that need to be paid attention to in the survey process.

A generic framework for geotechnical subsurface modeling with machine learning

This study introduces a generic framework for geotechnical subsurface modeling, which accounts for spatial autocorrelation with local mapping machine learning(ML) methods. Instead of using XY coordinate fields directly as model input, a series of autocorrelated geotechnical distance fields(GDFs) is designed to enable the ML models to infer the spatial relationship between the sampled locations and unknown locations. The whole framework using GDF with ML methods is named GDF-ML. This framework is purely data-driven which avoids the tedious work in the scale of fluctuations(SOFs)estimating and data detrending in the conventional spatial interpolation methods. Six local mapping ML methods(extra trees(ETs), gradient boosting(GB), extreme gradient boosting(XGBoost), random forest(RF), general regression neural network(GRNN) and k-nearest neighbors(KNN)) are compared in the GDF-ML framework. The results show that the GDFs are better than the conventional XY coordinate fields based ML methods in both accuracy and spatial continuity. GDF-ML is flexible which can be applied to high-dimensional, multi-variable and incomplete datasets. Among these six methods, GDF with ET method(GDF-ET) clearly shows the best accuracy and best spatial continuity. The proposed GDF-ET method can provide a fast and accurate interpretation of the soil property profile. Sensitivity analysis shows that this method is applicable to very small training dataset size. The associated statistical uncertainty can also be quantified so that the reliability of the subsurface modeling results can be estimated objectively and explicitly. The uncertainty results clearly show that the prediction becomes more accurate when more sampled data are available.

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.

Incorporating geotechnical and geophysical investigations for underground obstruction detection:A case study

Determining the location and boundary of underground obstructions and/or anomalies is a common problem and often a great chal-lenge for tunneling and underground construction.In this study,geotechnical investigations(penetration tests and borehole drilling/sam-pling)and geophysical investigations(surface wave method and cross-hole seismic method)were conducted with the aim of identifying the location and boundary of rock obstructions in Changi East,Singapore.The surface wave method is frequently used in the sites with lateral homogeneity in previous studies,but its application in the sites with rock obstructions is rare.The experimental results of this study indicate that the surface wave method is also able to determine the upper surface of rock obstructions,but difficult to identify the lateral and bottom boundaries of rock obstructions.To improve the precision of detection,the full waveform inversion(FWI)method was used to process the data from the cross-hole seismic survey.The results indicate that the inversion precision of P-wave is higher than that of S-wave.The horizontal and vertical ranges of rock obstructions in the P-wave inversion results are 14–26 m and 7.5–11.0 m respectively,roughly consistent with the results of penetration tests(about 15–25 m)and borehole log(8.85–10.80 m).This result proves that the sequential application of first-arrival time analysis and FWI can effectively delineate the boundary of rock obstruc-tions.Finally,the results of various detection methods were analyzed and compared in this study.Considering the advantages of various methods,we propose a cost-effective and high-precision workflow containing both geotechnical and geophysical investigations.

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.

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.

“岩土工程勘察”课程“理论+案例+实践”教学模式优化与创新探究

本文围绕“岩土工程勘察”课程开展调查研究,构建“理论+案例+实践”教学模式以提升学生分析和解决实际问题的能力,详细分析了该教学模式的理论基础、结构框架及实施过程。教学模式创新面临强化理论基础、案例更新、新技术及规范融合等挑战,需要校企合作、增加国家职业资格考试内容、优化理论学时结构等策略来推动。通过对教学框架的深入探究,以期为岩土工程勘察领域的学科教学改革提供新思路与实践经验。

新工科背景下岩土工程勘察课程思政元素挖掘与融入路径探讨

“新工科”和“课程思政”教育理念的提出及融合给高校人才培养提出了全新挑战和改革动力,如何在“新工科”背景下推行课程思政教学改革,培养具有优秀思想政治素养的“新工科”人才是高校面临的重要任务。以中国地质大学(武汉)岩土工程勘察课程为着力点,结合学科专业特点和学生认知需求,设计课程思政目标,挖掘了四个维度的思政元素,构建了课程思政全阶段闭环融合路径,完善了课程教学目标需求,丰富了课程教学内容及资源素材,创新了教学方法和手段,拓展了岩土工程勘察课程的深度、广度和温度,实现了专业学习和价值引领相结合的育人目标,形成了工程类专业课课程思政教学模式新探索。

能源行业“岩土工程勘察”实践教学改革研究

岩土工程勘察是土木工程领域的重要组成部分,对于培养合格的工程师以及促进能源行业的发展至关重要。传统课堂教学难以满足学生对实践经验的需求,因此校外实习成为提高学生综合素质的有效途径。本论文就能源行业“岩土工程勘察”实践教学进行改革研究,以提高工程学生的实际技能和专业素养,并结合我国能源行业的发展现状,改革实践内容以推动我国能源行业的可持续发展。该研究旨在为学生提供实际的工程项目经验,促进学习和实践的结合,培养工程师所需的综合素质。本研究分析了校外实习的重要性,指出了目前岩土工程勘察实践教学存在的问题,还介绍了一些成功的实施案例并对其成功经验进行总结,并提出改革后的实践方式与内容,最后总结了模式的潜在益处和挑战。

长春市某建筑场地地质勘察及剪切波速特征研究

以吉林省长春市某拟建项目为研究对象,基于相关技术规范,采用钻探取样、剪切波速试验等方法进行工程地质勘察。查明场地范围内地层岩性分布和水文地质条件,确定地基承载力特征值,判定土层渗透系数、场地土的类型和液化程度等;利用4种常见函数模型,针对不同土体甄选出精度较高的拟合函数,为场地周边区域建设剪切波速的验证和预测提供参考;根据场地工程地质条件,结合拟建筑物的特性,提出基础设计及施工方案建议。

钛合金厂房岩土工程勘察实践

围绕钛合金厂房岩土工程展开,探讨了岩土工程勘察实践过程及技术路线。通过详细评估地质地貌特征、地下水状况、地基承载力、变形特性,结合现场勘察、勘测、测试和分析,提出了相应的风险评估和对策建议,为项目的顺利实施提供了重要支撑。论述了解决问题的方法,分析了相关挑战,并得出了相应的观点和结论,为岩土工程领域的进一步研究和实践提供了一定参考。

岩土工程勘察报告中的评价及建议问题研讨

岩土工程勘察报告应以土力学理论为基石,以技术标准及规范为路标,依据客观、真实的基础资料,研析合理的岩土工程参数,提出恰当的评价及建议。基于岩土工程勘察中的问题,对以下三方面展开讨论:采用标贯法进行液化判别评价应注意计算公式中地面标高选择原地面还是后期整平地面问题,必要时应分不同标高进行评价;浅埋基岩以上地基处理方案如建议嵌岩刚性桩与土共同作用,应明确计算模型为土岩组合地基;应考虑场地的地形条件、区域地质条件及结构设计条件,综合分析确定抗浮设防水位。

武汉长江Ⅰ级阶地原状土样获取技术研究

本文分析了原状土样获取的技术标准现状和行业现状,研究了钻进方式、取样工具选取的适宜性综合分析、土样的封装及运输。对比试验研究表明,在武汉长江Ⅰ级阶地粘土层段采用锤击钻进配合使用敞口薄壁取土器,在砂土层采用锤击和回转组合钻进配合使用内置环刀取土器,辅以胶盖自封和胶带密封,取得的原状样品在现场质量评测、室内样品制备性和试验性方面均有比较良好的表现,基于此套方法获取的原状样原始结构受扰动较小,土的原始结构力保持良好。

济宁市中心城区第四纪地层划分及地质结构特征

济宁市中心城区第四纪地层广泛分布,是影响城市发展建设的重要地质因素。长久以来,区内第四纪地层划分的研究薄弱,各单位划分标准不统一,地层划分混乱,相关地质资料通用性差。本文依托“济宁市城市地质调查项目”,采用多种测年手段进行地质年代测定,并与工程地质钻探、岩土工程勘察相结合,对第四纪地层进行了研究划分。结果表明,全新世与晚更新世地层界线为黑土湖组;晚/中更新世地层界线埋深约为20.0~28.0 m,为一层钙质结核富集黏土层;中/早更新世地层界线亦为钙质结核富集黏土层,埋深约在50.0~65.0 m。第四系厚度一般90.0~130.0 m,与新近纪馆陶组呈不整合接触,二者地层特征差异明显。本次研究工作可为济宁市中心城区地质调查、岩土工程勘察等工作提供参考依据,弥补了以往研究的不足。

岩土工程勘察数字化技术与实现

分析了地质三维建模方法,提出虚拟钻孔、地层尖灭和透镜体、空间插值拟合等问题的解决办法。基于地理信息系统建立岩土工程勘察数据库,探讨了原始数据、中间数据、输出数据的特点和组成;最后,以某滑坡治理工程为研究对象,建立了三维勘察模型,以期为数字化技术在岩土工程勘察中的应用提供指导。

基于CPTU解释黏性土不排水抗剪强度方法研究

黏性土的不排水抗剪强度Su是海上风电工程设计中重要的力学参数之一,孔压静力触探测试(简称CPTU)无法直接测得黏土强度,但其所提供的锥尖阻力、侧摩阻力以及孔隙水压力与土体的不排水抗剪强度存在映射关系,国内外基于CPTU已经演化出多种解释土体不排水抗剪强度计算公式。基于滨海某海上风电项目,开展了原位CPTU试验、三轴不固结不排水(UU)、三轴固结不排水(CU)、固结快剪(CQ)以及船上微型十字板剪切(MVST)试验,对已有计算公式的适用性进行了校验,分析发现需根据区域场地情况对其中经验系数进行相应的调整以提高计算精度。研究基于CU试验结果,结合工程实例对原有公式中经验参数进行优化修正,最后通过误差分析,验证了修正预测模型的准确性与合理性,利用改进后的修正预测模型可使江苏地区海域黏性土不排水抗剪强度的计算得到更准确的结果。