Effects of Compaction Energy on Soils for Earthwork Construction in Sa Kaeo Province

The objective of this research was to study effects of energy applied to soil compaction used in construction. Soil samples were collected in four areas of construction sites in Sa Kaeo province to perform compaction test and CBR in the laboratory in order to evaluate relations between soil types, maximum dry density, optimum moisture content along with the values of CBR and soil swelling, based on changes of the energy on 3 levels such as 290 kJ/m3, 604 kJ/m3 and 2,748 kJ/m3. The results revealed that the maximum dry densities increased with compaction energy while optimum moisture content decreased accordingly. It is also found that the properties of compacted soils such as soil consistency (liquid limit and plasticity index), soil swelling, CBR were in linear relations to the quantity of soil particles smaller than 0.075 mm besides the compaction energies. The results thus can be used to predict the maximum dry density, optimum moisture content, swelling and CBR in order to control quality for the appropriate design and earthwork constructions

Stabilization of Water Treatment Sludge with Cement for use in Road Materials

งานวิจัยนี้มีวัตถุประสงค์ในศึกษาการปรับปรุงคุณภาพดินตะกอนประปาโดยใช้ซีเมนต์เป็นสารเชื่อมประสานและทำการทดลองหาอัตราส่วนของซีเมนต์ที่เหมาะสม เพื่อให้ได้ดินซีเมนต์ที่สามารถใช้เป็นวัสดุงานทางได้ตามต้องการ ศึกษาคุณสมบัติทางวิศวกรรมของดินตะกอนที่ปรับปรุงคุณภาพโดยการทดสอบกำลังรับแรงอัดแกนเดียวที่อายุการบ่ม 3 และ 7 วัน ตลอดจนศึกษากลไกของปฏิกิริยาเคมีโดยทำการวิเคราะห์สารผลิตภัณฑ์ที่เกิดจากปฏิกิริยาไฮเดรชั่นและสังเกตการเปลี่ยนแปลงโครงสร้างระดับจุลภาคของดินตะกอนประปาซีเมนต์โดยใช้เครื่อง X - Ray Diffraction (XRD) และกล้องจุลทรรศน์อิเล็กตรอน (SEM) ตามลำดับ จากผลการศึกษาในเบื้องต้นพบว่าดินตะกอนประปาตากแห้งที่ลานตากตะกอนมีปริมาณความชื้นค่อนข้างสูงอยู่ในช่วง 120 - 130 เปอร์เซ็นต์ เมื่อนำมาทดลองผสมซีเมนต์ที่อัตราส่วน 150, 200, และ 250 กิโลกรัมต่อลูกบาศก์เมตร พบว่ามีการพัฒนากำลังอัดค่อนข้างต่ำถึงแม้ว่าค่ากำลังรับแรงอัดจะมีแนวโน้มที่เพิ่มขึ้นตามอายุการบ่ม จากการศึกษาพบว่ากำลังของดินตะกอนประปาผสมซีเมนต์สามารถปรับปรุงได้โดยใช้เทคนิคการปรับลดปริมาณความชื้นเริ่มต้นก่อนผสมทำให้ได้อัตราส่วนน้ำต่อซีเมนต์อยู่ในช่วงที่เหมาะสมส่งผลให้มีการพัฒนากำลังอย่างรวดเร็วที่อายุการบ่มระยะสั้น อัตราส่วนปริมาณความชื้นของดินตะกอนประปาต่อปริมาณซีเมนต์ (w/c ratio) ในช่วง 3.07 - 1.84 ทำให้ดินตะกอนประปาผสมปูนซีเมนต์มีค่ากำลังรับแรงอัดเพิ่มขึ้นอยู่ในช่วง 5.06 - 16.43 กิโลกรัมต่อตารางเซนติเมตรและมีศักยภาพในการนำไปใช้เป็นวัสดุชั้นรองพื้นทางดินซีเมนต์ในงานถนน ผลการทดสอบคุณสมบัติทางด้านเคมีกายภาพจากการวิเคราะห์โดย X - Ray Diffraction (XRD) พบว่าสารผลิตภัณฑ์หลัก Calcium Silicate Hydrate (CSH) มีปริมาณเพิ่มขึ้นตามปริมาณอัตราส่วนผสมและอายุการบ่ม นอกจากนี้ยังพบว่าสารผลิตภัณฑ์ Calcium Sulfoaluminate Hydrate (Ettringite) ที่เกิดขึ้นในช่วงต้นของปฏิกิริยามีส่วนสำคัญที่ช่วยทำให้ดินซีเมนต์มีโครงสร้างที่แน่นขึ้นจากการสังเกตภาพถ่าย Scanning Electron Microscopy (SEM) พบว่าสารผลิตภัณฑ์ CSH และ Ettringite สานตัวปกคลุมทั่วบริเวณพื้นผิวและเชื่อมโยงอนุภาคดินตะกอนซีเมนต์โดยเฉพาะในตัวอย่างที่มีการพัฒนากำลังที่สูงขึ้นซึ่งสอดคล้องกับผลการวิเคราะห์ XRD และกำลังรับแรงอัดแกนเดีย

Potential of Computer-Aided Engineering in the Design of Ground-Improvement Technologies

The progress status of jet-grouting construction during the construction phase is difficult to verify and even after the completion of construction, it can be verified only by empirical methods. This study attempted to recreate a realistic simulation result of the middle-pressure jet-grouting method by establishing a computer-aided engineering (CAE) system from the planning/design stage of the ground model and verifying the validity of the construction process after the model was analyzed by the moving particle semi-implicit (MPS) method. The governing parameters for the ground were determined by the MPS simulation of the unconfined compression test. The construction simulation was analyzed and the results were validated by visual confirmation of the related phenomena, such as the soil-improved body formation and mud discharge. To verify the accuracy of the mud discharge phenomenon, three different probe regions were set above the model ground and the amount of mud discharge generated in each region was computed before drawing an overall conclusion of the study. A soil-improvement body of approximately 0.38 m3 was observed to have formed at the end of the study and the highest mud discharge particle number measured, for instance, was 896. This study is expected to serve as a guideline for further studies on simulation-based research

Numerical Simulation of the Liquefaction Phenomenon by MPSM-DEM Coupled CAES

The mechanism of liquefaction and the factors that cause liquefaction behavior have previously been examined and evaluated, both analytically and experimentally; construction including liquefaction countermeasures is being implemented, based on these findings. This study presents a theoretical visualization of the mechanism of liquefaction generation and evaluates the behavior of particles in the ground. Specifically, an MPSM-DEM coupled CAE system (CAES) is employed to view the events beneath the ground, modeled three-dimensionally when an external acceleration is applied to simulate seismic waves and reveals the behavior below the surface. The numerical simulation of the liquefaction phenomenon, as represented by an MPSM-DEM coupled CAES system, clearly showed the mechanism of liquefaction generation and contributed to the design and accountability of more economical and sustainable liquefaction countermeasures, regardless of the field of specialization

Influence of Perforated Soils on Installation of New Piles

In recent years, there has been an increasing demand to replace ancient structures. The removal of such structures also involves the removal of the existing piles that supported the structures, and the backfilling of the pulling-out holes that formed during the removal. However, there are no standard guidelines for the backfilling of pulling-out holes. At present, therefore, each owner or contractor must determine the material and the construction method to use for backfilling. This results in a difference between the mechanical properties of the original soil and those of the soil that has been backfilled, namely, the soil on which a newly built structure will be constructed. In this study, it was assumed that a new pile would be installed on a perforated soil (that is, the soil left after removing the existing piles) where the mechanical properties differ between the original soil and the backfilled soil. The behavior of the new pile, when installed on the boundary of a soil between two types of mechanical properties, was evaluated by a three-dimensional linear elastic analysis. When the new pile was installed at the boundary between the two types of soil with different mechanical properties, most of the new pile was inclined to the soil side where the N value was relatively small. However, the inclination of the new pile was able to be suppressed by increasing the distance from the boundary between the two types of soil

Influence of Perforated Soils on Installation of New Piles

In recent years, there has been an increasing demand to replace ancient structures. The removal of such structures also involves the removal of the existing piles that supported the structures, and the backfilling of the pulling-out holes that formed during the removal. However, there are no standard guidelines for the backfilling of pulling-out holes. At present, therefore, each owner or contractor must determine the material and the construction method to use for backfilling. This results in a difference between the mechanical properties of the original soil and those of the soil that has been backfilled, namely, the soil on which a newly built structure will be constructed. In this study, it was assumed that a new pile would be installed on a perforated soil (that is, the soil left after removing the existing piles) where the mechanical properties differ between the original soil and the backfilled soil. The behavior of the new pile, when installed on the boundary of a soil between two types of mechanical properties, was evaluated by a three-dimensional linear elastic analysis. When the new pile was installed at the boundary between the two types of soil with different mechanical properties, most of the new pile was inclined to the soil side where the N value was relatively small. However, the inclination of the new pile was able to be suppressed by increasing the distance from the boundary between the two types of soil

Time-Series Prediction of Long-Term Sustainability of Grounds Improved by Chemical Grouting

In the field of geotechnical engineering, the problems of liquefaction and land subsidence are of major concern. In order to mitigate or prevent damage from liquefaction, the chemical injection method is actively used as one of the countermeasures for ground improvement. However, a complete understanding of the long-term sustainability of improved grounds is still unavailable due to a lack of knowledge of the influencing parameters. Thus, the chances of chemical injection accidents cannot be ruled out. In this study, the compressive strength of improved grounds by the granulated blast furnace slag (GBFS), one of the grouting materials used in the chemical injection method, was evaluated and used for a time-series prediction of long-term sustainability. The objective of this study was to evaluate the accuracy and validity of the prediction method by comparing the prediction results with the test results. The study was conducted for three different models, namely, the autoregressive integrated moving average (ARIMA) model, the state-space representation (SSR) model, and the machine learning predictive (MLP) model. The MLP model produced the most reliable results for the prediction of long-term data when the input information was sufficient. However, when the input data were scarce, the SSR model produced more reliable results overall. Meanwhile, the ARIMA model generated the highest degree of errors, although it produced the best results compared to the other models depending on the criteria. It is advised that studies should be continued in order to identify the parameters that can affect the long-term sustainability of improved grounds and to simulate various other models to determine the best model to be used in all situations. However, this study can be used as a reference for the selection of the best prediction model for similar patterned input data, in which remarkable changes are observed only at the beginning and become negligible at the end

Applicability of Additives for Ground Improvement Utilizing Fine Powder of Waste Glass

As a solidifying material for ground improvement using inorganic waste as a raw material, the authors have been developing an additive mixture of the fine powder of waste glass containing a large amount of silica generated during the production of glass cullet and an alkaline aid (heat-treating type of “Earth-Silica; ES” additive). Furthermore, a solidifying material that solidifies by mixing this additive with the fine powder of blast furnace slag, which is a by-product of steel production, is also being developed. In this study, the authors reviewed the mixing process of the solidified materials, especially the one made with the heat-treating type of ES additive, omitting the heat treatment of the fine powder of waste glass and the alkaline aid and applying only the mixing treatment. As a result, a mixing type of ES additive was manufactured to simplify the manufacturing process, and the difference in the performance of the solidifying material, depending on the presence or absence of the heat-treating process during the additive manufacturing, was verified in terms of the effect on the solidifying action. Specifically, the solidifying materials to which the heat-treating type of ES additive and the mixing type of ES additive were added, respectively, were applied to the high-pressure injection stirring method, one of the ground-improvement methods. Various tests clarified the changes in viscosity of these solidifying materials over time and the acceleration of their solidifying rates when adding ordinary Portland cement separately

Numerical Analysis for Ground Subsidence Caused by Extraction Holes of Removed Piles

Around the world, and especially in Japan, the tearing down of social infrastructure, including civil engineering structures, has been increasing due to the aging of these constructions, which were built during a period of high economic growth, and a decrease in their utilization caused by a recent drop in the population. The number of existing pile foundations being pulled out has gradually risen to a higher number than that of pile foundations being newly installed. However, after the pulling-out of a pile foundation, the mechanical characteristics of the surrounding ground are of great concern due to the existence of the holes that form when the existing piles are removed (extraction holes). In this study, a three-dimensional elasto-plastic consolidation analysis was performed to examine the effect of the extraction holes of removed piles on the static properties of the surrounding ground. As examples of the results of the analysis, if an extraction hole of a removed pile is left as it is, large ground subsidence will occur near the extraction hole of removed pile, especially at the lower part of the clay layer near the hole. The greater the number of extraction holes of removed piles, the greater the compressive stress acting on the extraction holes after the pile removal. Therefore, the filler should exhibit strength early as the number of extraction holes of removed piles increases