Focus of study



Key research parameter

Prediction of excavation-induced ground and wall movement



Small-strain soil behavior


Empirical + numerical

3D distribution of soil movements, small strain behavior of the soil



Plane strain problem, modes of wall displacement



Constitutive soil models, displacement of tieback wall


Modified mobilizable strength design (MSD) method

Deformation of multipropped excavation, excavation geometries, strength mobilization characteristics of soil



Sheet pile wall installation, construction sequence and bracing



Diaphragm wall deflection, ground surface settlement, excavation depths, geological conditions



Narrow excavations, support stiffness, excavation width-depth ratio

Effect of groundwater (GW) dewatering



Watertightness Assessment Test before excavation, stability of the bottom of the excavation, defects in the enclosure (gaps or open joints)


State-of-the-art review

Ground settlement, interactions between the retaining wall-dewatering well, the dewatering-excavation, and dewatering-recharge


Field observations

Wall deflection (diaphragm wall/secant-bored pile wall), ground surface settlement, stage of excavation, groundwater drawdown


Case study

Dewatering (pumping rate and depth of a cutoff wall), soil properties, building settlement


Review on water leak incidents

Water ingress (leak through joints & seepage-prone weak zone), surface settlements and diaphragm wall deflection

Design and support optimization


Robust geotechnical design (RGD)

Braced excavation, wall deflection, Cost-efficiency (costs of the diaphragm wall, the bracing system, excavation/disposal of the dirt, dewatering, and instrumentation)


RGD coupled with first order second moment (FOSM) method

Braced excavation (geometry and depth), wall deflection, uncertainties of soil parameters (noise factors), cost efficiency, robustness and safety


Constructing indicator system of optimization of supporting schemes based on TOPSIS

Technical feasibility, effect reliability (such as static and dynamic performances), construction accessibility (complexities during construction), economic rationality


Numerical analysis

Bearing capacity, stability design requirements, and environmental requirements during construction, composite support systems, soil arching effect between existing pile foundations (bending moment in the piles)


FEM for analysis, BS8081:1989 for ground anchor, BS8002:1994 for toe stability check, BS 5950 and CIRIA Special Publication 95 for strutting elements

Secant pile retaining wall, water-tightness, ability to vary the depth of retaining wall for irregular soil profiles, HS-Small model, grouting techniques, excavation support stability, assessment of surrounding infrastructure’s damage