Compared with the water-base drilling fluid, oil-based drilling fluid has always been one of the important technical guarantees in high temperature deep well, high-inclination directional well and all kinds of complex seismic exploration. With 5#white oil selected and taken as continuous phase, emulsifying agent, organic soil, tackifier, fluid loss agent, lime, other treatment agents and dosages are optimized and the optimal formula of oil-base drilling fluid is determined. This new type environmentally-friendly oil-base drilling fluid possesses good rheological properties, suspension capability, high temperature stability, stronger anti-pollution ability and common emulsion-breaking voltage of more than 2000 V. During the field application, this fluid possesses regular borehole diameter, good lubricity, stable borehole, simple preparation process, easy site maintenance and good reservoir protection features. Furthermore, it can solve complex formation, water expansion of clay shale, poor lubrication & drag reduction effect, poor reservoir protection effect and other technically-difficult problems.

Geological and topographical challenges in fault zones pose significant risks to the structural integrity of buried pipelines. Previous studies have shown that continuously buried pipelines using loose sand as backfill material experience severe damage under active fault displacement. This study proposes the use of super-absorbent- polymer concrete (SAPC) as an alternative trench backfill to mitigate structural damage in buried pipelines subjected to reverse fault movement, as opposed to conventional backfill with loose sand. This study begins with the preparation of lightweight porous concrete containing large super-absorbent-polymer aggregates, followed by mechanical property testing to establish a constitutive model of SAPC. The SAPC is then employed to backfill the trench of a fault-crossing pipeline. A finite element model is developed to analyze the pipeline-SAPC trench- soil interaction and evaluate the performance of the pipeline when the trench is backfilled with SAPC. Critical parameters such as SAPC backfill length, overlying thickness, and elastic modulus are also examined for their effects on the performance of a buried pipeline. The numerical results indicate that compared with conventional backfill with loose sand, the critical reverse fault displacement of the pipeline can generally be increased by over 100 % after using SAPC as the backfill material. Optimal pipeline performance is observed when the SAPC backfill length is approximately 60 times the pipeline diameter. Besides, a thinner overlying SAPC thickness will generally enhance the performance of buried steel pipelines under reverse fault movement. Additionally, by adjusting the sand-cement ratio and SAP volume fraction, a SAPC with a higher elastic modulus can slightly improve the performance of the fault-crossing pipeline.

This paper presents a comprehensive design study conducted in Saudi Arabia, focusing on the performance evaluation of an inverted T foundation system in a building constructed on expansive soils. The study aimed to investigate the causes of damage and evaluate the performance of a proposed inverted T foundation. A single story market building in a semi-arid region with expansive soil was constructed utilizing a 40 cm-thick mat foundation as a precautionary measure against soil swelling. However, the building experienced instability and damage shortly after completion. This study explored the replacement of the existing mat foundation with an inverted T foundation. The research involved assessing the ability of the inverted T foundation to withstand swelling pressures and its impact on the structural members of the building. Design guidelines and tools were developed to support the design and analysis of the inverted T foundation. Economic feasibility was also evaluated. The study compared the effects of swelling pressure on two types of foundations: a mat foundation and a rigid strip foundation. The results showed that the inverted T foundation demonstrated less upward movement and was found more effective in mitigating the detrimental effects of soil expansion compared to the mat foundation. Design guidelines and tools, including schedules, and charts were developed to support the design and analysis of the inverted T foundation. The findings have significant implications for the design and construction of buildings on expansive soils, offering insights into the effectiveness of the inverted T foundation as an alternative solution. The research contributes to the knowledge of foundation design on expansive soils in general and provides practical guidance for engineers and practitioners in similar geological contexts.

Rock abrasivity plays an important role in the machine design, construction scheduling, and budgeting of TBM projects. Establishing several faster and simpler estimation equations for the Cerchar Abrasivity Index (CAI) of rocks is, therefore, very important. This study investigated the correlation between the CAI and mechanical properties of rock, rock mass classification parameters, and machine performance. A TBM construction database including 159 tunnel sections is established. Several acceptable and practical estimation equations of CAI are developed using simple and multiple regression analysis (0.66 < R-2 < 0.76). In this process, a normalized specific energy is proposed to evaluate the machine performance. The results show that the rock compressive strength and brittleness index are the most dependent parameters to explain CAI, and the estimated rock mass strength also indicates a close correlation. In addition, the contribution of a rock mass classification system and machine performance index for estimating CAI cannot be ignored. Finally, the estimation performance of the developed equations is compared and evaluated, and a new method for selecting an optimal model based on ranking is proposed. Since the input parameters of the proposed equations can be readily available at the project planning stage, they are very practical for TBM designers, tunnel designers, and contractors.

This study analyzes the progression, utilization, and inherent challenges of traditional non-linear static procedures (NSPs) such as the capacity spectrum method, the displacement coefficient method, and the N2 method for evaluating seismic performance in structures. These methods, along with advanced versions such as multi-mode, modal, adaptive, and energy-based pushover analysis, help determine seismic demands, enriching our grasp on structural behaviors and guiding design choices. While these methods have improved accuracy by considering major vibration modes, they often fall short in addressing intricate aspects such as bidirectional responses, torsional effects, soil-structure interplay, and variations in displacement coefficients. Nevertheless, NSPs offer a more comprehensive and detailed analysis compared to rapid visual screening methods, providing a deeper understanding of potential vulnerabilities and more accurate predictions of structural performance. Their efficiency and reduced computational demands, compared to the comprehensive nonlinear response history analysis (NLRHA), make NSPs a favored tool for engineers aiming for swift seismic performance checks. Their accuracy and application become crucial when gauging seismic risks and potential damage across multiple structures. This paper underscores the ongoing refinements to these methods, reflecting the sustained attention they receive from both industry professionals and researchers.