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• A two-stage analysis method is proposed for analyzing the issue of local crack expansion in buildings under the influence of pit construction. • A three-dimensional fluid–solid coupling model of pit construction was established, along with a local structural crack expansion model based on XFEM. • The numerical model takes into account the initial cracks in the building and analyzes the impact of the size of these initial cracks. • Crack expansion control measures for damaged buildings are proposed. In response to safety concerns arising from pit construction near existing damaged buildings, this paper introduces a two-stage analysis method. Initially, the finite element method is utilized to construct a comprehensive model of pit excavation, enabling the analysis of building settlement and internal forces induced by the construction activity. Subsequently, the resulting building settlement vectors are employed as displacement loads in a localized structural model established via the extended finite element method. This facilitates the examination of crack propagation within the damaged building under settlement influence. Application of the proposed method to a new pit construction scenario reveals a maximum differential settlement of the building at 5.35 mm. As building settlement increases, crack propagation within the building follows a slow-fast-slow trend, with an approximate crack propagation length of 9.6 m and an average depth of 0.13 m. Notably, deeper and longer initial cracks exacerbate wall crack propagation, leading to cracks penetrating the wall when initial crack depths exceed 100 mm. Furthermore, crack propagation extends to the slab, resulting in a 10.2 m long of crack when initial crack depth is 66 mm. A case study demonstrates the effectiveness of the proposed two-stage analysis method in addressing crack propagation issues in existing buildings during pit construction. [ABSTRACT FROM AUTHOR]

The textile-reinforced mortar (TRM) combines high-strength fabric textiles with cementitious mortar matrix to enhance mechanical behaviour and durability, especially at high temperatures. The current study investigated how basalt, carbon, and glass textile grids and TRM composites respond under direct tensile and thermal loading up to 800 ℃. Changes in microstructure were analyzed using scan electron microscopy (SEM), thermo-gravimetric analysis (TGA), and ultrasonic pulse velocity (UPV). The results indicated that temperature significantly affected the coating material and cementitious mortar, weakening the grids and composite specimens. Carbon and glass fibre grids proved more resilient, and the carbon and glass TRM reduced 50% of their ultimate stress at 500 ℃, while for basalt TRM is 200 ℃. A slight gain of strength was observed for all TRM specimens at 300 ℃, and SEM analysis revealed critical changes in the mortar matrix and interfacial transition region. The results were further utilized to calibrate the Gibson model considering humidity and early-stage coating material changes, and yielding results consistent with experimental data. • The thermomechancial tensile behaviour of basalt, carbon, and glass fabric TRM and textiles were presented. • The experimental results were further investigated with the use of a analytical model. • The micro-level experiments were conducted to study the variation under high temperatures. [ABSTRACT FROM AUTHOR]

Marine controlled-source electromagnetic (CSEM) method has proved its potential in detecting highly resistive hydrocarbon bearing formations. To image the subsurface resistivity, this paper presents the first application of a frequency domain CSEM inversion approach using fictitious wave domain timestepping modelling. Each inversion iteration requires the gradient of the misfit with respect to resistivity computed by the product between the forward and adjoint fields. Simulation of the adjoint field using fictitious time modelling is challenging as it requires the time domain adjoint source functions while only a few discrete frequencies of the data residual are available for the inversion. To overcome this issue, we formulate a regularized linear inverse problem to estimate a long time series from very few frequency samples. It can then be solved using linear optimization technique in matrix-free manner. Instead of computing adjoint source time function one by one at each receiver location, a basis function implementation has been designed, such that the linear inversion can be solved only once and then reused every time to construct all time-domain adjoint sources. The method allows computing all frequencies of the EM fields in one go without heavy memory and computational overhead. Numerical examples are employed to demonstrate the application of our method. • The first CSEM inversion using fictitious wave domain timestepping modelling is developed. • The adjoint source time function is estimated by solving a regularized linear inverse problem. • The basis functions are computed matrix-free, once and reused for all receivers. • The numeric examples demonstrate its application to practical 3D CSEM inversions. [ABSTRACT FROM AUTHOR]

Abstract: GPU has become a booming technology in reverse time migration (RTM) to perform the intensive computation. Compared with saving forward modeled wavefield on the disk, RTM via wavefield reconstruction using saved boundaries on device is a more efficient method because computation is much faster than CPU–GPU data transfer. In this paper, we introduce the effective boundary saving strategy in backward reconstruction for RTM. The minimum storage requirement for regular and staggered grid finite difference is determined for perfect reconstruction of the source wavefield. Particularly, we implement RTM using GPU programming, combining staggered finite difference scheme with convolutional perfectly matched layer (CPML) boundary condition. We demonstrate the validity of the proposed approach and CUDA codes with numerical example and imaging of benchmark models. [Copyright &y& Elsevier]

Abstract: Interpolating the missing traces of regularly or irregularly sampled seismic record is an exceedingly important issue in the geophysical community. Many modern acquisition and reconstruction methods are designed to exploit the transform domain sparsity of the few randomly recorded but informative seismic data using thresholding techniques. In this paper, to regularize randomly sampled seismic data, we introduce two accelerated, analysis-based two-step interpolation algorithms, the analysis-based FISTA (fast iterative shrinkage-thresholding algorithm) and the FPOCS (fast projection onto convex sets) algorithm from the IST (iterative shrinkage-thresholding) algorithm and the POCS (projection onto convex sets) algorithm. A MATLAB package is developed for the implementation of these thresholding-related interpolation methods. Based on this package, we compare the reconstruction performance of these algorithms, using synthetic and real seismic data. Combined with several thresholding strategies, the accelerated convergence of the proposed methods is also highlighted. [Copyright &y& Elsevier]