
Yutao PanNorwegian University of Science and Technology | NTNU · Department of Civil and Environmental Engineering
Yutao Pan
PhD (National University of Singapore)
About
77
Publications
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Introduction
Dr Pan currently works at the Department of Civil & Environmental Engineering, Norwegian University of Science and Technology (NTNU). The current projects are 'Mobilized strength of spatially variable cement treated soil.' and 'Geometric imperfection of cement treated soil ground'.
Additional affiliations
Education
August 2012 - December 2016
July 2010 - June 2012
July 2006 - June 2010
Publications
Publications (77)
This study examines the effect of geometric imperfections arising from variations in both the diameter and orientation of jet-grouted columns on the water-tightness of a jet-grouted cut-off wall. A three-dimensional discretised algorithm is used to detect and measure the discontinuities in the wall. A statistical evaluation of the gross flow rate t...
In this study an effective stress model for cement-treated soil is employed to carry out a systematic study on cement-treated soil slab used to control the wall displacement in excavations with thick, soft clay layers. Deterministic analyses were first conducted to assess the drainage state of the treated soil slab. These indicate that, under times...
Spatially variable cement-treated ground can be considered, in design, as a uniform medium with appropriately reduced strength. Various strength reduction factors have been proposed for cement-treated ground under different loading conditions. However, the Tresca and Mohr–Coulomb models, which are widely used to represent the behaviour of the impro...
Cone penetration testing (CPT) has become one of the most commonly adopted in situ tests for site investigations, due to its reliability and repeatability of the measurements and the potential for direct use in design. For CPTs in clays, previous studies have paid considerable attention to the selection of penetration resistance factor Nkt consider...
Artificial barriers are widely used to prevent leakages. However, due to construction errors during the wall installation, passages with small dimensions may occasionally penetrate through the barrier, undermining its tightness. A three‐dimensional discretized algorithm (TDA) is proposed for quantitatively estimating the transient‐state discharge r...
Current theoretical works on excavation-induced ground settlement in clays for small radius curve tunnels typically treat the shield as a continuous entity, neglecting the influence of the articulation device. Consequently, the accurate assessment of over-excavation effects resulting from changes in the small curvature shield excavation route is im...
Previous studies take less account of analytical solution analysis for buried pipeline under the action of active fault. Furthermore, current theoretical studies of fault‐pipeline interactions generally treat the structure as continuous pipeline, with less attention given to the effect of joints. This paper provides an analytical method to estimate...
With the increasing demand for transportation construction in coastal areas, tunnel safety research is becoming increasingly important. Previous studies take less account of the nonlinear wave and current action under the sloping seabed terrain. Furthermore, there are few researches on the additional deformation of shield tunnel lining caused by wa...
This Special Issue aims to comprehensively address every facet of geotechnical engineering (foundation support structures on land and on the seabed, such as high-rise buildings and bridges and offshore installations such as platforms, pipelines and bottom structures) and ocean engineering (coastal structures, offshore platforms and other ocean syst...
Underground cut-off walls are widely used in various geotechnical applications to hinder groundwater flow, contaminant transportation and possibly heat conduction. Cut-off walls were usually found defective due to construction errors during the installation phase, leading to significant leakages in subsequent operation phase. Existing physics-based...
Current design practice of spudcans in clay generally ignores the influence of installation and subsequent operation on the spudcan elastic stiffness. In reality, soil consolidation around the post-installation spudcan can cause the elastic stiffness to evolve with time, thus affecting the safe and stable operation of jack-up platforms. This paper...
In heavily urbanised areas, the construction of tunnels underneath existing ones is unavoidable and much caution has to be exercised in both design and construction so as not to undermine the safety of the structure and vehicles. In this paper, a non-linear soil-tunnel interaction model is developed to evaluate the tunnel behaviour that is induced...
Risk assessment of earth dams is concerned not only with the probability of failure but also with the corresponding consequence, which can be more difficult to quantify when the spatial variability of soil properties is involved. This study presents a risk assessment for an earth dam in spatially variable soils using the random adaptive finite elem...
This paper examines the effect of dynamic compaction by multi-point tamping on the densification of sandy soil between adjacent impact points. First, by using a three-dimensional finite element analysis, tamping was modelled using drop weight with prescribed impact velocity. The numerical model was then validated with centrifuge model test results...
Current theoretical solutions for the influence of landslides on existing structures are generally conducted on the assumption of fine weather and provide little attention on the rainfall intensity and duration risk. Furthermore, previous studies on the interaction mechanics between landslides and pipelines seldom take account of the impacts of joi...
The evaluation of influence of heavy rainfall on tunnel structural construction is a problem being faced by engineers around the world. Current analytical solutions on the tunnelling-induced ground movements are generally based on the normal sunny weather and provide little attention on the rainfall intensity and duration risk. In this paper, a tim...
Most of urban ground collapses and tunnel failures are caused by joint leakage of shield tunnel lining. This paper conducts a series of model tests and particle flow simulations aiming to investigate the geo-hazards and explore the associated failure mechanism due to tunnel leaking. Based on critical width of leaky joint, taking leaky joint locatio...
In order to study the effects of recycled aggregate with different particle gradations and different contents on the mechanical properties of cement soil modified by nano-MgO, unconfined compressive strength and scanning electron microscope (SEM) tests were carried out. The cement content was fixed at 15% and the nano-MgO content was 1.5%. The effe...
Municipal waste incineration bottom ash (IBA) is a by-product of municipal waste incineration and is characterized by possessing non-cohesive and enriching in irregular particles. Associated with particles breakage, using such problematic materials as filler initiates the degradation of structure durability and mechanical properties in geotechnical...
Limited mathematical analytical studies for tunnel leakage-induced surface and subsurface soil movements and tunnel responses incorporated the distribution of excess pore water pressure, in which the concrete lining was often assumed perfectly permeable or impermeable. This mechanical closed-form model will bring calculation errors and inconsistenc...
This paper presents a framework for modelling the random variation in permeability in cement-admixed soil based on the binder content variation and thereby relating the coefficient of permeability to the unconfined compressive strength of a cement-admixed clay. The strength–permeability relationship was subsequently implemented in random finite ele...
In this paper, the strength, ductility and microstructure behavior of cement-treated silt with polypropylene fiber was studied by a host of experimental studies. The influence of fiber content (the weight of dry soil was 0.75%, 1.0%, 1.25%, 1.5%, 1.75% and 2.0%), curing time (7, 14 and 28 days) and freeze–thaw cycles (3, 6, 9, 15 and 30) on the unc...
The landslides have an important influence on the force and deformation of existing tunnels, which may adversely affect the liner structures and even endanger normal operation. Current scholars have made few efforts to investigate the reinforcement measures for existing tunnels in the landslide region, and even paid less attention to probe into the...
Electric vertical drains (electrokinetic geosynthetics with filtration, drainage, reinforcement, and electrical conductivity function) have been used as electrodes and vertical drains in the treatment of soft clay by vacuum preloading combined with electroosmosis. A series of laboratory model tests was performed to investigate the possibility of op...
Tunnel excavation in mountainous region frequently encounters high local inflows as a consequence of hydraulic head and multiple faults geology, which may adversely affect the serviceability of tunnel structures. Previous researches, however, paid very little attention to the seepage field of rocks around deep buried tunnels adjacent to water-beari...
The stability assessment of a soil embankment in the flooding season has attracted increasing attention in recent years. The current study performs a coupled hydraulic-mechanical analysis of an embankment subjected to water level fluctuation. The coefficient of permeability of embankment soils is represented by a uniform random field with upper and...
The long-term leakage of lining under train loading has a significant impact on the consolidation settlements around shield tunnel and the rheological behavior of viscoelastic porous soils will further exacerbate this consequence, which adversely affect the adjacent geo-environments and the subsidence of existing structures. At present, the assumpt...
This paper presents the measurement and prediction of the tunnelling-induced surface response in karst ground, Guangzhou, China. A predictive method of ground settlement is proposed named as the expanding deep learning method. This method kinetically uses the expanding tunnelling data to predict ground settlement in real time. Four types of deep le...
Current analytical solutions on the ground movements and stresses induced by shield tunneling in soft soils are generally based on the instantaneous excavation behavior. Furthermore, previous studies seldom took account of the influence of surcharge loading during tunnel excavation process. This paper introduces a complex variable analytical soluti...
Cement-admixed soil columns are often used to strengthen the surrounding soft soil for enhancing tunnel stability. Such improved soil surrounds possess high spatial variability and heterogeneity in the strength and stiffness properties. In this paper, three-dimensional random finite-element analysis is conducted to compute the equivalent strength a...
The post-installation consolidation settlement of spudcan foundations is an issue of concern for the offshore jack-up industry, especially when jack-up rigs operate for long periods. Although there are field records of excessive spudcan settlement during the rig operation, there are no guidelines available for operators to assess and project the co...
This paper presents an experimental study on the effect of polypropylene fibres on the yielding behaviour of cement-admixed soft marine clay. A range of mix ratios is investigated, with the cement content spanning from 20% to 100%. The unconfined compression strength is first examined, followed by isotropic compression and subsequently shearing in...
The importance of accurate prediction of limiting cavity depths during offshore spudcan foundations installation has been variously highlighted in the literature. Nonetheless, most of the previous research is deterministic in nature and confined to homogenous soils. Since offshore clayey soils can be highly spatially variable, there is a practical...
Shield-driven tunneling will encounter huge risk of potential accidents as a consequence of groundwater level surprising variation in the course of construction. Current studies seldom take account of the groundwater level variation during construction for tunneling-induced ground and tunnel responses. Moreover, little work is conducted on the anal...
Soil-bentonite cutoff walls are usually used to contain the contaminants of landfills. The pumpability, permeability, and adsorption capability of the slurry are all crucial to the performance of the cutoff wall. In this study, the effect of polyvinyl alcohol (PVA) was used to improve the performance of bentonite slurry. A series of lab tests were...
Diaphragm walls are commonly used as cut-off walls to prevent water from entering dewatered excavation pits, landfills and downstream water. However, due to the geometrical imperfections such as the positioning error of grab during trenching, small seepage passages through the diaphragm wall may occasionally occur, which will undermine its water-ti...
This study explores the mechanism of the undrained response of tunnelling through spatially variable improved soil. It is found that spatial variability produces a more realistic failure mechanism compared to that produced by the conventional homogeneous assumption. The overall failure of the improved ring through which the tunnel passes occurs whe...
Jet-grouted cutoff walls (JGCOWs) and jet-grouted earth-plugs (JGEPs) are commonly used as artificial water barriers to impede groundwater from seeping downstream of dams or into deep excavation pits. However, due to positioning errors and variability of column diameters, seepage passages may occasionally penetrate through the water barrier, thus u...
Cement-stabilised soil layers (CSSLs) are often created to enhance lateral support to the retaining wall below the excavation level, such as those widely used in the construction of common service tunnels in Singapore. The CSSLs may be subjected to tensile stress or even cracks due to the underlying uplift pressure. Fully-coupled effective stress a...
Uniaxial or triaxial compression test of cylindrical rock specimens using rock mechanics testing machine is a basic experimental method to study the strength and deformation characteristics of rock and the development process of rock fracture. Extensive literature review has been conducted on this issue; meanwhile, experimental and numerical studie...
When a large-diameter shield tunnel boring machine enters or exits a tunnel, the newly exposed tunnel face is prone to instability and water seepage. In order to prevent collapse of the tunnel face, local ground improvement can be used until the permanent tunnel lining can be installed. The tunnel launching project of the Nanjing Metro Line 10 cros...
Evaluation of the strength of cement-treated clay with a broad range of mix ratios and curing periods was conducted using unconfined compression tests (UCTs). The influence of cement content, total water content, and curing period on the unconfined compressive strength of cemented clay are investigated. It is found that, at constant total water con...
In Eurocode EC7, a “characteristic” strength is used as a cautious estimate of the local average strength that governs the bearing capacity of the foundation. The objective of this paper is to examine the correlation between the local average strength and the bearing capacity of a stiff caisson foundation resting on spatially variable ground using...
This paper summarizes some of the recent works on spatial variability of cement-treated clay for underground construction. The studies were conducted using deterministic and random finite element analyses, calibrated and validated using centrifuge model test data. An approach to estimating a ‘design strength’ of an equivalent homogeneous material i...
At present, there is no well-accepted method for the design of tunnels built in cement-admixed soils. Moreover, spatial variability and heterogeneity in strength have been reported for such treated soils. This paper presents a two-dimensional plane-strain study of tunnel stability in cement-admixed soft soil surrounds considering spatial variabilit...
This study examined a composite foundation that was improved by the joint usage of two types of columns: soil-cement and stone columns. The composite foundation that consists of soil-cement columns, stone columns, and natural soils is herein referred to as a multicolumn composite foundation (MCF). Explicit expressions of the equivalent modulus of t...
Spatial variability in the radius of a jet-grout column is commonly encountered in practice. Although various prediction models for the column radius are available, they have been generally used to predict a nominal radius. The radius variation within a column has been seldom considered. In this study, the intracolumn radius variation was simulated...
This paper examines the usefulness and challenges in using an advanced effective stress constitutive model in random finite element study on the effect of spatial variability on global behaviours of axially-loaded cement-treated clay column. The main challenge lies in the large number of parameters which need to be simplified and the amount of data...
The effect of geometric imperfections in both diameter and position of jet-grouted columns on the watertightness of an underground cement-treated slab is investigated in this study. A three-dimensional discretized algorithm is proposed to facilitate the detection and measurement of untreated zones that penetrate the treated slab. The normalized flo...
This technical note proposes a modified log-linear compression relationship for the pre-yield isotropic compression behavior of cement-Admixed marine clay. The difference between this modified relationship and the conventional log-linear relationship is the use of the tensile strength as an added stress to the mean effective stress. This allows the...
The material properties of cement-admixed soil vary spatially. Statistical parameters such as mean, coefficient of variation and scale of fluctuation were used to characterize the spatial variability of cement-admixed soil. In this paper, an advanced constitutive model for cement-admixed marine clay is firstly randomized by relating model parameter...
Buried culverts are usually considered to be earthquake-resistant underground structures. Therefore, few studies have been conducted to investigate the seismic response of slab culverts under high fill embankment which are usually subjected to extreme dynamic loads. This paper presents a numerical analysis of the seismic response of slab culvert un...
Excavation of foundation pits and tunnels will inevitably influence the working performance of adjacent loading piles, thus, it is important to accurately evaluate the additional pile responses due to soil excavation. In order to overcome the deficiency of the conventional Winkler's foundation beam model, a modified nonlinear two-stage analysis met...