Geotechnical Engineering Investigation Research Articles

Analysis of the performance of frequency-Bessel transformation surface wave tomography method in geotechnical engineering investigation

Abstract The frequency-bessel transform surface wave tomography method has emerged as a novel method for surface wave imaging during the past few years. This technique facilitates imaging large-scale crust-mantle structures and enables shallow engineering exploration. Compared to conventional methods like SPAC, it markedly enhances the quality of the surface wave dispersion curve, particularly in higher mode, enhancing the reliability of inversion. Its active and passive source data processing integration is particularly noteworthy, significantly broadening surface wave methods’ application scope. Our research reviews the performance of this technique in addressing common geological issues encountered in geotechnical engineering investigation, such as bedrock surface detection, cover layer detection, karst detection, and permafrost layer detection. Moreover, it recommends this innovative technique’s widespread adoption and further advancement.

Water-holding properties and electrochemical characterization of the soil under the Grand Deliverance Hall of the Chongshan Temple, Taiyuan City, China: providing the basis for preventing groundwater erosion in historic buildings

Many historic buildings are at serious risk of deterioration due to changes in the moisture content of the soil under the buildings. Based on the typical deterioration problems of the Grand Deliverance Hall and the cultural relics in the hall, this study analyzes and concludes that the main factor affecting the generation and development of deterioration is groundwater erosion through environmental monitoring and geotechnical engineering investigation. The impact of changes in moisture content on the water-holding properties and pore distribution of the soil under the cultural-relics buildings was further assessed. Then, combined with the soil property, our study provides a novel and effective way to monitor and reflect the water-holding properties of the soil using electrochemical detection. The connected pore resistance and matrix suction decrease with the increase in the moisture content, both showing a power function law. Changes in moisture content cause changes in the thickness of the double electric layer, which in turn affects the connected pore resistance and matrix suction of soil. The greater the connected pore resistance, the greater the matrix suction and the water holding capacity. Finally, based on the research of this study and the conservation ideology of cultural relics that respects the original and minimizes intervention, protection recommendations to prevent groundwater erosion are proposed in order to provide guidance for future research.Graphical

Application of computer geological model in geotechnical engineering investigation

The computer geological model is the approximate model of the actual complex geological phenomenon. During the modeling process, uncertainty from various sources can lead to deterioration of the quality of geological models. In order to ensure the usability of the model, it is necessary to consider the influence of spatial autocorrelation and interrelationship between strata on information transmission and uncertainty when analyzing and predicting multi-layer geological structures. The purpose of this paper is to improve the accuracy and testing breadth of computer modeling by studying geotechnical exploration activities. The calculation formula of information entropy of geological variables is given. At the same time, it introduces how to calculate the maximum information entropy of geological variables under the prior distribution according to the prior information constraints, and how to calculate the results of geological variables under the posterior distribution by using Bayesian updating. This paper introduces the calculation method of formation attribute probability field and iterates formation probability from bottom to top. The results show that the Copula method can improve the geological model in statistical sense. Finally, it is concluded that establishing 3D geological model by computer is helpful to improve the accuracy of geological exploration.

Digital monitoring of rotary-percussive drilling with down-the-hole hammer for profiling weathered granitic ground

Rock and geotechnical engineering investigations involve drilling holes in ground with or without retrieving soil and rock samples to construct the subsurface ground profile. On the basis of an actual soil nailing drilling for a slope stability project in Hong Kong, this paper further develops the drilling process monitoring (DPM) method for digitally profiling the subsurface geomaterials of weathered granitic rocks using a compressed airflow driven percussive-rotary drilling machine with down-the-hole (DTH) hammer. Seven transducers are installed on the drilling machine and record the chuck displacement, DTH rotational speed, and five pressures from five compressed airflows in real-time series. The mechanism and operations of the drilling machine are elaborated in detail, which is essential for understanding and evaluating the drilling data. A MATLAB program is developed to automatically filter the recorded drilling data in time series and classify them into different drilling processes in sub-time series. These processes include penetration, push-in with or without rod, pull-back with or without rod, rod-tightening and rod-untightening. The drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six drillholes. Each curve is found to contain multiple linear segments with a constant penetration rate, which implies a zone of homogenous geomaterial with different weathering grades. The effect from fluctuation of the applied pressures is evaluated quantitatively. Detailed analyses are presented for accurately assess and verify the underground profiling and strength in weathered granitic rock, which provided the basis of using DPM method to confidently assess drilling measurements to interpret the subsurface profile in real time.

Experimental Study on Axial Stress and Hammer Impacting Energy of Offshore Standard Penetration Test

Standard penetration test (SPT) has been widely used in offshore exploration because of its unique advantages. Unlike onshore exploration, offshore construction areas are characterized by high waves and water depths ranging from several meters to tens of meters. As a result, the reliability of offshore SPT is significantly reduced compared with onshore SPT. Currently, the probe rod length correction of SPT is not involved in geotechnical engineering investigation codes and related research, which greatly limits the application of this method in offshore exploration. Therefore, a series of SPTs were carried out in offshore environments with different water depths, with a maximum rod length of 65 m. The acceleration and axial stress at each test point of the rod were monitored by the dynamic signal data acquisition system, and the hammer impacting energy at each test point was obtained by Force–Velocity (F-V) method. The test results show that the correction of the rod length of the offshore SPT is different from that of the traditional SPT, and it needs to be further corrected for the water depth. In this paper, a modified method of rod length for offshore SPT is proposed, which can provide reference for the application of offshore SPT.

Application of Long-Range Cross-Hole Acoustic Wave Detection Technology in Geotechnical Engineering Detection: Case Studies of Tunnel-Surrounding Rock, Foundation and Subgrade

The adverse geological conditions of soil cave, karst cave and goaf in deep foundation directly affect the safety and economy of geotechnical engineering construction. It is a difficult problem in geotechnical engineering detection to detect the distribution of bad geological conditions efficiently and accurately. Aiming at the problems of short penetrating distance and low resolution of cross-hole acoustic wave detection in rock-soil mass, based on the characteristics of acoustic wave propagation in rock and soil layers and comprehensively utilizing the spark source and data acquisition device, a long-distance cross-hole acoustic wave detection technology is proposed. According to the indoor concrete model test and field tests of geotechnical engineering, the applicability of the long-distance cross-hole acoustic wave detection technology in the detection of geotechnical structure and adverse geological phenomena under complex geological conditions is verified. The results show that acoustic wave CT imaging can accurately detect the cavities in the indoor concrete model test. In addition, the field tests of the grouting effect of tunnel-surrounding rock, high-rise building foundation and subgrade further verify the rapidity, accuracy and intuitiveness of the long-distance cross-hole acoustic wave detection technology. This work provides a reference for eliminating the potential safety problems caused by adverse geological conditions and similar geotechnical engineering investigation.

Research on Prediction Model of Rock and Soil Layer Information Based on Adjacent Boreholes

Aiming at the problem that the drilling core cannot be drilled and core is unable to be drilled to find the stratum due to the construction measures or large equipment occupation in the survey site, based on the thickness information of the adjacent hole position of the borehole to be measured, the BP neural network model for stratum prediction was constructed, and the training data sampling method and comprehensive analysis results were put forward, which were based on the training data sampling method and comprehensive analysis results in the front, back, left, right and circle positions of the borehole, combined with the actual investigation Engineering. The influence of soil layer training data collected by different methods on the accuracy of soil layer thickness prediction was analyzed. The results showed that: (1) By comparing the prediction results of 10 groups of actual engineering holes to be measured, it was revealed that the prediction accuracy of soil thickness had great correlation with the orientation selection. (2) In azimuth prediction, each group collects 21 adjacent boreholes as training data samples by continuous cycle of three longitudinal and seven horizontal directions. The prediction results of neural network were stable. (3) A selection strategy was proposed to analyze the preliminary prediction results of neural network. Based on the circular prediction results, the data with the difference within ±0.2m in azimuth prediction were compared and screened. The comprehensive prediction value obtained by test was very close to the true value, and the data error is within 9%, and the prediction effect was good. The research results provide a way of thinking for the prediction of small sample soil sequence, and can provide reference for geotechnical engineering investigation and design application.

Discussion on Geotechnical Engineering Investigation and Analysis of High-rise Building and Application Research of Foundation Treatment Technology

Discussion on Geotechnical Engineering Investigation and Analysis of High-rise Building and Application Research of Foundation Treatment Technology

Discussion on the Focus of Geotechnical Engineering Investigation of Deep Foundation Pit Engineering

Discussion on the Focus of Geotechnical Engineering Investigation of Deep Foundation Pit Engineering

Analysis of Karst Hydrogeological Problems in Geotechnical Engineering Investigation

Analysis of Karst Hydrogeological Problems in Geotechnical Engineering Investigation

Exploration on Application of Geotechnical Engineering Investigation Technology under Complicated Geological Conditions

Exploration on Application of Geotechnical Engineering Investigation Technology under Complicated Geological Conditions

Research and Application of Comprehensive Investigation Technology in Geotechnical Engineering Investigation

Research and Application of Comprehensive Investigation Technology in Geotechnical Engineering Investigation

Key Points of Geotechnical Engineering Investigation in Deep Foundation Pit Engineering

Key Points of Geotechnical Engineering Investigation in Deep Foundation Pit Engineering

Analysis of Geotechnical Engineering Investigation and Foundation Construction Treatment Technology

Analysis of Geotechnical Engineering Investigation and Foundation Construction Treatment Technology

Study on Drilling Ground Collapse Induced by Groundwater Flow and Prevention Based on a Coupled CFD-DEM Method

Given the hazards caused by drilling ground collapse (DGC) due to groundwater flow in the processes of geotechnical engineering investigation, a coupled computational fluid dynamics and discrete element method (CFD-DEM) method is adopted to numerically simulate the development of hazards. An improved coupling program is employed to realize the two-way coupling between open-source CFD code OpenFOAM and commercial DEM software PFC3D. The coupling program allows complex meshes generated by ANSYS ICEM to be imported into PFC3D. The feasibility and accuracy of the CFD-DEM method are first verified by simulating a single spherical particle settling in hydrostatic water and the formation of the repose angle of sandpiles. Then, this method is adopted to investigate the patterns of stratum deformation and foundation loss, typical particle flow processes, and characteristics of drilling rig toppling. Finally, measures for prevention of DGC induced by groundwater flow are discussed in detail. Two typical strata, including a water-rich sand stratum and a water-rich sand-clay compound stratum, are considered. The research results show that for the water-rich sand stratum, DGC induces a “bowl”-shaped settlement trough, and the maximum value of ground surface settlement is proportional to the foundation loss rate. For the water-rich sand-clay compound stratum, a “jar”-shaped settlement trough is created. Four typical particle flow processes are involved in DGC. The drilling rig topples toward the center of the settlement trough. The maximum displacement appears at the top of the tower and has an approximate linear correlation with the groundwater flow velocity. The measures and methods of DGC prevention are also summarized in detail. The results of this research provide a reference for hazard prevention and delicacy control of DGC induced by groundwater flow.

Analysis of Common Problems in Geotechnical Engineering Investigation and Research on Measures

Analysis of Common Problems in Geotechnical Engineering Investigation and Research on Measures

Analysis on Geotechnical Engineering Investigation and Foundation Design

Analysis on Geotechnical Engineering Investigation and Foundation Design

Explore Geotechnical Engineering Investigations Hydrogeological Problems during Design and Construction

Explore Geotechnical Engineering Investigations Hydrogeological Problems during Design and Construction

Research on the Development Trend of Geotechnical Engineering Investigation Technology

Research on the Development Trend of Geotechnical Engineering Investigation Technology

Discussion on the Geotechnical Engineering Investigation and Foundation Treatment Technology

Discussion on the Geotechnical Engineering Investigation and Foundation Treatment Technology