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The dual-purpose diaphragm wall, serving as both a temporary retaining structure and the permanent exterior wall of underground structures, has been extensively used for deep excavations in soft soil areas. Within some cases, soil mix panels are installed on both sides to enhance ground deformation suppression during excavation. Further research is essential to assess the effectiveness of this type of retaining structure in mitigating ground deformation caused by excavation in specialized soft soil areas. This paper utilized monitoring data to present a case study on the deformation characteristics of a 20.6-m-deep excavation supported by diaphragm walls supplemented by soil mix panels in soft soils, detailing its impact on adjacent pipelines and buildings. The findings revealed significant creep deformation properties of the surrounding ground. The diaphragm walls can effectively confine deformations caused by deep excavations to a limited extent. When supplemented with soil mix panels, greater deformation control efficacy can be achieved. Notably, the combined diaphragm and soil mix wall system exhibits maximum lateral displacements ranging from 0.07% to 0.22% of the excavation depth (H) and maximum ground surface settlements between 0.05%H and 0.25%H. The maximum surface settlement occurs within a region 0.5-1.5 times the maximum wall deflection. The region from 0 to 0.75 H distance from the retaining wall represents the maximum area of surface settlement, with the affected zone extending up to 4.0 H due to the influence of adjacent excavation construction. Significant spatial corner effects are displayed by the square excavation pit. Influenced by the pit's corner effects, pipelines and buildings near the midspan of the pit experience greater subsidence, resulting in an overall subsidence pattern with the most severe settlements occurring near the planview middle of the retaining system.

期刊论文 2025-07-01 DOI: 10.1061/IJGNAI.GMENG-10638 ISSN: 1532-3641

The under-consolidated state affects the deformation behavior of deep excavation in soft soil and poses potential risk to the safety of adjacent facilities. However, the deformation model of deep excavation in under-consolidated ground has not been well investigated yet. This study presents a series of numerical analyses on the deformation characteristics of deep excavations in under-consolidated and normally-consolidated ground, each of which is retained by diaphragm walls with rigid struts and a bottom improvement layer. Under-consolidated cases without excavation activities (i.e., simplified as Consolidate cases) were also included for comparison. The modelling results showed that, with the lateral constraint of inner rigid support system, the under-consolidated ground resulted in only a slight increase of lateral wall deformation but a significant increase in ground settlement as compared to normally-consolidated ground. The under-consolidated ground with lower initial average consolidation ratio, thicker surface fill, higher permeability, and longer construction period produced greater wall deformation and ground settlement during excavation. Besides, this study proposed an empirical method to estimate the settlement envelope for deep excavation in under-consolidated ground as the superposition of two parts: settlement induced by excavation activities, and settlement induced by residual consolidation with consideration of average consolidation ratios before and after excavation.

期刊论文 2025-06-16 DOI: 10.1680/jgeen.24.00253 ISSN: 1353-2618

This paper uses a simplified assessment method based on the excavated-induced ground movement to examine the coupling effect between adjacent excavations during construction. The finite element numerical model is established to simulate and analyze the deformation of adjacent excavations at each stage of construction. Distinct construction sequences are employed to explore the dissimilarities in the deformation characteristics of the surrounding soil and envelope after excavation. The results indicate that when adjacent excavations are excavated simultaneously, their interactions affect the soil and envelopes' deformation. The maximum ground settlement occurs at a certain distance from the edge of the excavation. As the excavation depth increased, the enclosure exhibited a more pronounced deformation. The deformation of the enclosure structure can be significantly inhibited by the spatial effect at the corners of the excavation. When adjacent pits are constructed in different construction sequences, the enclosure structure on the first constructed excavation often experiences greater deformation than on the later constructed excavation.

期刊论文 2025-06-01 DOI: 10.1007/s10706-025-03184-1 ISSN: 0960-3182

Significant movement of in-situ retaining walls is usually assumed to begin with bulk excavation. However, an increasing number of case studies show that lowering the pore water pressures inside a diaphragm wall-type basement enclosure prior to bulk excavation can cause wall movements in the order of some centimeters. This paper describes the results of a laboratory-scale experiment carried out to explore mechanisms of in situ retaining wall movement associated with dewatering inside the enclosure prior to bulk excavation. Dewatering reduces the pore water pressures inside the enclosure more than outside, resulting in the wall moving as an unpropped cantilever supported only by the soil. Lateral effective stresses in the shallow soil behind the wall are reduced, while lateral effective stresses in front of the wall increase. Although the associated lateral movement was small in the laboratory experiment, the movement could be proportionately larger in the field with a less stiff soil and a potentially greater dewatered depth. The implementation of a staged dewatering system, coupled with the potential for phased excavation and propping strategies, can effectively mitigate dewatering-induced wall and soil movements. This approach allows for enhanced stiffness of the wall support system, which can be dynamically adjusted based on real-time displacement monitoring data when necessary.

期刊论文 2025-06-01 DOI: 10.1016/j.undsp.2025.01.003 ISSN: 2096-2754

This paper uses the three-dimensional numerical simulation method to analyze the first deep foundation pit project directly above the operating subway in a certain area. The monitoring data were compared with the numerical results to verify the accuracy of the numerical model, and then a series of analyses were performed. The soil beneath the tunnel is the most direct object of tunnel deformation caused by the excavation of deep foundation pits above the tunnel. The rebound deformation of the soil beneath the tunnel forces the tunnel to produce an upward deformation cooperatively. Therefore, after comparing and analyzing the prevention criteria of traditional excavation measures, which were not sufficient for this project, a new method of fortification is proposed for the foundation pit above the tunnel, which is called the micro-disturbance drill pipe pre-reinforcement method (PRM) for the soil beneath the tunnel. The comprehensive parameter analysis of the PRM shows that the PRM can effectively reduce the uplift value of the tunnel, and the reinforcement effect is obvious.

期刊论文 2025-05-24 DOI: 10.1007/s11709-025-1175-6 ISSN: 2095-2430

In soft soil regions, the construction of irregular-shaped excavations can readily disturb the underlying soft clay, leading to alterations in soil properties that, in turn, cause significant deformations of the excavation support structure. These deformations can compromise both the excavation's stability and the surrounding environment. Based on a large-scale, irregular-shaped excavation project for an underground interchange in a soft soil area, numerical simulations were performed using Midas GTS to analyze the overall foundation pit deformationn. The study explored the effects of groundwater lowering, excavation, and local seepage on the disturbance of surrounding soils and the resulting foundation pit deformationn. The findings reveal that the irregular-shaped excavation exhibits distinctive spatial deformation characteristics, with the arcuate retaining structure's arching effect reducing the diaphragm wall's horizontal displacement. Groundwater lowering exerts a stronger disturbance on shallow soils near the excavation and a weaker disturbance on deeper soils. Excavation-induced stress redistribution notably affects the soils above the excavation surface and those within the embedded region of the support structure. Local seepage primarily disturbs the soils surrounding the leakage point. Additionally, the weakening of soil parameters significantly influences the foundation pit deformationn. Combined disturbance (dewatering + excavation + leakage) induced 32%, 45%, and 58% greater displacements compared to individual factors, confirming the critical role of multi-factor coupling effects.

期刊论文 2025-05-14 DOI: 10.3389/feart.2025.1532635

BackgroundArchaeological limestone artifacts are subject to several deterioration factors that can cause harm while they are buried in soil, such as wet salt soil. Thus, one of the biggest challenges is restoring limestone artifacts that have been discovered from excavations. Understanding the nature of limestone after extraction and the resulting alterations, such as the stone's structural instability and the high salt content of the artifacts, are prerequisites for the restorer. In 1974 AD, King Ramesses III's gate was excavated from the ancient Heliopolis Temple in Cairo. The stones were removed from the soil and left on display outdoors at the same excavation site, where they were subject to seasonal variations in temperature and environmental changes. The main objective of the research is to select the best consolidating materials suitable for the pieces of limestone stone artifacts discovered from archaeological excavations due to their special nature, which affects them as a result of their presence in burial soil for long time. Selecting appropriate consolidating materials with appropriate characteristics was important. In order to withstand a range of environmental circumstances. The characteristics of the ancient stones at the King Ramesses III Gate site were investigated and analyzed to ascertain their true state, and their percentage of damage was calculated by contrasting them with the identical natural limestone that had not been subjected to any harmful influences. After that, experimental samples were used, and the efficacy of the treatment materials was assessed.ResultExperimental study aims to evaluate the effectiveness of some traditional and nano composites materials to improving the properties of stone artifacts extracted from archaeological excavations. Three consolidating solutions were used as follows, paraloid B72 dissolved in acetone 3%, and Calcium hydroxide nanoparticles dissolved in paraloid polymer with acetone at concentrations of 1% and 3%, in addition to nano calcium carbonate dissolved in paraloid polymer with acetone 1% and 3%. The efficiency of the consolidate materials were evaluated using a scanning electron microscope SEM, as well as measuring the water contact angle, in addition to color change testing and measuring the physical and mechanical properties.ConclusionNano materials are considered better than paraloid B72 as a consolidated material and the best outcomes results were obtained with a nano calcium carbonate dissolved in paraloid polymer with acetone 3%.

期刊论文 2025-05-13 DOI: 10.1186/s43088-025-00636-8

Dewatering and excavation are fundamental processes influencing soil deformation in deep foundation pit construction. Excavation causes stress redistribution through unloading, while dewatering lowers the groundwater level, increases effective stress, and generates seepage forces and compressive deformation in the surrounding soil. To systematically investigate their combined influence, this study conducted a scaled physical model test under staged excavation and dewatering conditions within a layered multi-aquifer-aquitard system. Throughout the experiment, soil settlement, groundwater head, and pore water pressure were continuously monitored. Two dimensionless parameters were introduced to quantify the contributions of dewatering and excavation: the total dewatering settlement rate eta dw and the cyclic dewatering settlement rate eta dw,i. Under different experimental conditions, eta dw ranges from 0.35 to 0.63, while eta dw,i varies between 0.32 and 0.82. Both settlement rates decrease with increasing diaphragm wall insertion depth and increase with greater dewatering depth inside the pit and higher soil permeability. An analytical formula for dewatering-induced soil settlement was developed using a modified layered summation method that accounts for deformation coordination between soil layers and includes correction factors for unsaturated zones. Although this approach is limited by scale effects and simplified boundary conditions, the findings offer valuable insights into soil deformation mechanisms under the combined influence of excavation and dewatering. These results provide practical guidance for improving deformation control strategies in complex hydrogeological environments.

期刊论文 2025-05-02 DOI: 10.3390/buildings15091534

Previous theoretical studies on the deformation of shield tunnels induced by foundation pit excavation generally consider the stratum as a linear elastic body, which seldom take the irregular construction boundary into account. Meanwhile, Curved beam theory and Timoshenko beam theory are less applied in the study of tunnels. This paper provides an analytical method to predict the displacements of small curved tunnels caused by deep excavation with time effects. Firstly, by introducing the fractional derivative Merchant model, a mechanical approach is proposed for analyzing the structural deformation of neighboring tunnels induced by foundation pit excavation. The parameters of viscoelastic soils are further derived in the Laplace domain based on time variability properties. Secondly, the additional stress field on existing small curvature tunnels is solved with theory of viscoelastic Mindlin solution and load reduction in foundation pits. Moreover, a deformation calculation model for curved shield tunnels is established by applying Pasternak foundation and Timoshenko beam theory. The time domain solutions for the radial and vertical deformations of small curvature tunnels are then derived by finite difference method along with Laplace positive and inverse transforms. In addition, the engineering measured data and three-dimensional numerical simulation solutions are compared with the analytical solution to verify relatively accuracy. Finally, sensitivity analyses are performed for parameters such as the buried depth of tunnels, minimum clear distance, fractional order, excavation method and creep time.

期刊论文 2025-05-01 DOI: 10.1016/j.apm.2024.115920 ISSN: 0307-904X

This paper addresses the issue of crack expansion in adjacent buildings caused by foundation pit construction and develops a predictive model using the response surface method. Nine factors, including the distance between the foundation pit and the building, soil elastic modulus, and density, were selected as independent variables, with the crack propagation area as the dependent variable. An orthogonal test of 32 conditions was conducted, and crack propagation was analyzed using the FEM-XFEM model. Results indicate that soil elastic modulus, Poisson's ratio, and distance between the pit and building significantly impact crack propagation. A predictive model was developed through ridge regression and validated with additional test conditions. Single-factor analysis showed that elastic modulus and Poisson's ratio of the silty clay layer, elastic modulus of sandy soil, and pit distance have near-linear effects on crack propagation. In contrast, cohesion, density, and Poisson's ratio of sandy soil exhibited extremum points, with certain factors showing high sensitivity in specific ranges. This study provides theoretical guidance for mitigating crack propagation in adjacent buildings during excavation.

期刊论文 2025-05-01 DOI: 10.3389/fbuil.2025.1514217
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