Abstract: To explore the deformation behaviors of subway excavations in thick water-rich sandy strata and the characteristics of frequent through-wall leaking hazards, the databases of excavation deformation and through-wall leaking events are first built to carry out comprehensive statistical analyses; hence, the deformation laws of retaining walls and ground surface behind the walls are obtained, and the key influencing factors are identified. Then, a novel method for classifying through-wall leakages during deep excavation in water-rich sand is proposed; afterwards, their primary triggering factors are revealed, and the effective measures are also summarized. The statistical analyses show that: (1) The maximum lateral wall deflection, \delta _\texthm , varies from 0.03% H (H, excavation depth) to 0.48% H; the magnitudes of \delta _\texthm are affected by the spatial-corner effect, dewatering mode, burial condition of wall toes, and wall exposure length. (2) The profile of ground settlements is a typical concave shape, and the maximum settlement, \delta _\textvm , is 0.26% H_\texte ( H_\texte , final excavation depth), which occurs at about 0.5 H_\texte behind the walls. (3) Through-wall leaking causes sudden increments of \delta _\texthm , mainly attributed to the rapid increment of total lateral earth pressure induced by seepage force and/or the inappropriate grouting pressure. (4) Most of the leakage-induced settlement increments, \Delta \delta _\textv1 , are less than 0.5% H_1 , and the primary influence zone could be extended to about 2 H_1 outside the pit, in which H_1 denoted the burial depth of leaky spots on the wall; besides, the shape of strata disturbed behind the walls shows a distribution of "inverted cone". (5) Leaking hazards can be classified into three levels: minor seepage without soil loss, massive leakage with slight soil loss, and massive inrush of water and soils. (6) Through-wall leakages can be effectively controlled from the perspective of "disaster prevention before accidents and emergency response after accidents".