Jee Rou Ni, Darren Liew Yeong Chun, Dayang Zulaika Abang Hasbollah
et al.
Soft soils, characterized by low shear strength, high compressibility, and high-water content, present significant challenges in construction, often leading to excessive settlement and potential structural failure. Settlement is defined as the deformation of soil due to applied stresses. The primary mechanisms driving soft soil settlement include primary consolidation, where pore water pressure dissipates under sustained loading, and secondary compression. The rate of consolidation is influenced by factors like natural variability of the ground and soil permeabilities. Since soft soils are often unavoidable in construction, steps must be taken to enhance their strength to allow for safe and stable development. This paper explores three widely used ground improvement methods: preloading with Prefabricated Vertical Drains (PVDs), geosynthetics, and deep soil mixing (DSM). The usage, limitations, and feasibility of each method are discussed in detail to provide insights into effective mitigation strategies for soft ground construction.
Surv~val of transplanted Zostera marina L (eelgrass). Z mar111a growth, and envlronmental c o n d ~ t ~ o n s were studled concurrently at a number ot sltes In a southwestern tnbutary of the Chesapeake Bay to e luc~da te the factors l im~ting niacrophyte d~strlbution In thls region Cons~stent differences In surv~val of the tlansplants were observed, wlth no long-term survlval at any of the sites that were formerly vegetated w ~ t h t h ~ s pecles but that currently renialn unvegetated Therefore the current d l s t r~bu t~on f Z manna l~kely lepresents the extent of sultable env~ronmenta l cond~tions in the reglon, and the lack of recoxrry Into h~stor~cally veqetated s ~ t e s IS not solely due to lack of propagules Poor long-term survlval \vds reldted to seasonally h ~ g h levels of watel column l ~ g h t a t tenuat~on Fall transplants d ~ e d by the end of summer follow~ng exposure to levels of h ~ g h sprlng t u r b ~ d ~ t y (K, > 3 0) Accumulat~on of an e p ~ p h y t e ma t r~v durlng the late sprlng (0 36 to 1 14 g g ' dry cvt) may also have contributed to thls stress Differences In water column nutnent levels among sltes durlng the fall and wlnter (10 to 15 pM dissolved lnorqanic nltrogen and 1 pM dissolved inorganic phosphates) had no observable effect on e p ~ p h y t e accumulation or macrophyte growth Sallnlty effects were nnnor and there were no symptoms ot dlsease Although summertime cond~tions resulted In depress~ons In growth they d ~ d not alone 11m1t long-term surv~val It 1s suggested that water qua l~ ty condltlons enhancing adequate seagrass growth during the sprlng may be key to long-term Z manna surv~val and successful recolonizat~on in thls reglon